As the use of lithium-ion batteries in electric vehicles, portable electronic devices, power tools, and grid energy storage continues to increase, the demand for lithium resources is growing rapidly. In China, over 71% of lithium resources are stored in salt lakes, which are abundant in the Qinghai-Tibet Plateau. Among them, salt lakes in Qinghai province generally have the characteristics of high ratio of magnesium to lithium and low lithium content. Lithium extraction from high Mg/Li ratio salt lakes is a great challenge worldwide. This review focuses on the latest progress of Mg/Li separation and lithium extraction technologies from salt lake brine with high Mg/Li ratio. We comprehensively analyzed the features and applications in terms of principles, characteristics and performance of each method including extraction, adsorption, reaction/separation coupling technology, membrane and electrochemical method. The adsorption method is more suitable for high Mg/Li brine. The extraction method can be used for brine with a lower lithium concentration. The emerging new reaction-coupled separation technology can achieve high-efficiency lithium extraction and comprehensive utilization of magnesium and lithium resources. The membrane methods like nanofiltration, electrodialysis and bipolar membranes have the advantages of lower energy consumption and modularity. The electrochemical method has the simple equipment, but the system needs to be optimized yet. The extraction of lithium from salt lakes requires to increase the total yield, to improve the comprehensive utilization of related resources, to develop high-valued lithium products, and to strengthen the engineering technology. Finally, the goal is to utilize salt lake resources more efficiently, comprehensively and sustainably.

Magnesium resources are abundant in Qinghai Salt Lake, but it has not been effectively utilized for a long time. These facts lead to the serious waste of magnesium resources and hampered exploitation of potassium and lithium resources. It is of great significance to realize the multi-species, large-scale and high-value utilization of salt lake magnesium resources for the comprehensive development of salt lake resources. Mg-based layered double hydroxides (LDHs) are new type of intercalated functional materials. Based on the adjustable of microstructure, mesoscopic morphology and macroscopic properties of LDHs, the LDHs have been widely used as PVC heat stabilizer, UV-blocking material and smoke suppressant in polymeric materials and road construction. Researchers from State Key Laboratory of Chemical Resource Engineering in Beijing University of Chemical Technology have carried out systematic researches on intercalation structure design and intercalation assembly methods of LDHs based on the utilization of salt lake magnesium resources. Key technologies such as separate nucleation and aging steps and atomic economic reaction have been developed. A large variety of magnesium-based intercalated functional materials have been designed and constructed. The large-scale applications of Mg-based intercalated functional materials have provided new ideas for the comprehensive development and high-value utilization of magnesium resources in salt lake.

Salt lakes are well developed in China, which possess rich magnesium resources. The preparation of magnesium based functional materials with high-performance and high-value chemicals is an effective means to realize the sustainable development of magnesium resources in salt lake. Magnesium based layered double hydroxides (LDHs) is an important type of magnesium functional material. By virtue of the unique structural characteristics (e.g., tunability of layer metal ions and interlayer guest anions, and structure topological transformation), magnesium based LDHs have shown potential applications in petroleum, coal, fine chemistry and environmental pollution fields as precursors or supports. This article focuses on reviewing the research progress of magnesium-based hydrotalcite catalytic materials in recent years， and summarizes its structural regulation rules， so as to provide reference for the subsequent application of magnesium-based hydrotalcite catalytic materials.

With the rapid development of battery-powered vehicles and electronic products in recent years, there has been a dramatic increase in the global demand for lithium. Therefore, the development and use of lithium resources has also attracted increasing attention. Because there is a large amount of lithium in brine, the selective extraction of lithium from that resource has become the focus of intensive research in recent years. There are many techniques for extracting lithium from salt lakes. Among these, electrochemical lithium extraction has attracted considerable attention because it is green, safe, highly efficient, and saves energy. Herein, recent research into lithium extraction by electrochemical methods—both domestically and abroad—is reviewed. Such research includes the development of working electrodes and counter electrodes, and the construction of various electrochemical lithium extraction systems. In addition, suggestions and prospects are given for the future development direction of electrochemical lithium extraction.

Metal oxides catalysts have been widely used in a large variety of industrial processes, including ammonia synthesis, energy conversion and fine chemical synthesize. The morphology of metal oxides has an important effect on the catalytic performance. Compared to bulk materials, metal oxides catalysts with specific morphology exhibit unique structure properties in many aspects, which has become a research hotspot in the field of materials science. In this review, we highlight the preparation method, formation mechanism and structural property of metal oxides with various morphology, and their recent progresses in oxidation, steam reforming and hydrogenation are also reviewed. In the final section, future opportunities and challenges in the preparation of metal oxides catalysts are discussed, and some strategies to resolve these critical problems are further proposed.

Organic-inorganic composites have been widely applied due to their superior performances. Notably, the dispersion state of the inorganic nanofillers played significant roles in determining the quality and performance of the composites. It is of great importance to evaluate the dispersion state of inorganic nanofillers so that to construct organic-inorganic composites with designed performances. This paper introduced the traditional techniques and progress in the evaluation of the dispersion state for inorganic nanofiller in the composites. Some difficulties involving the sampling method and the scope of the measurement need to be solved. To this end, three-dimensional visualization of inorganic nanofillers in the composites has been proposed and discussed in this paper. Based on the fluorescent labelling of the inorganic nanofillers, including the pre-modification and post-labelling techniques, the inorganic nanofillers showed decent fluorescent emission. Three-dimensional imaging techniques were employed to acquire the location of inorganic nanofillers and the three-dimensional morphologies of the composites. Both qualitative and quantitative analysis have been applied to evaluate the dispersion state for inorganic nanofillers. The proposed fluorescent evaluation methodology can be adapted not only in the optimization of the technical process, but also in the non-destructive analysis of the finished products. In addition, the prospect of the structural visualization in organic-inorganic composites has also been discussed.

The extraction of lithium from salt lake brine has gradually become one of the crucial ways for the production of lithium and lithium related products in China. However, the high magnesium-to-lithium ratio of salt lake brines in China makes it difficult to extract lithium ions. Traditional solvent extraction processing of lithium from salt lake brine always requires a lot of co-extract and high concentration of acid, resulting in low product purity and high risk. A kind of butyl-cyclic tetrapyridine molecules for lithium extraction with solvent polar responsive molecular structure “isomerism” was designed and synthesized to realize “lithium-complexing” under polar conditions and “lithium-releasing” under non-polar conditions. The ¹H NMR and high resolution mass spectrometry were used to characterize the molecular structure of the target molecule. By comparing the spectral properties of the target molecule in the presence of Li⁺ and Mg²⁺, it is shown that the butyl-cyclotetrapyridine molecule has a strong selectivity to lithium ions. In addition, the results of ion transport across the supporting liquid membrane further indicate that butyl-cyclotetrapyridine molecules can achieve high selective extraction of lithium ions under different polar solvent conditions.

There are abundant magnesium resources in salt lake brine, and the primary utilization form at present is mainly to extract crystalline magnesium chloride. In order to improve the efficiency of the process, the scheme of directly separating high-purity crystalline magnesium sulfate by adding brine and changing temperature was put forward in this paper, and the changes of magnesium sulfate crystal micro-morphology and the influence of cooling rate on crystal morphology during the non-equilibrium dynamic cooling process of MgSO₄ saturated brine, MgSO₄-NaCl co-saturated brine and MgSO₄-NaCl-MgCl₂ co-saturated brine were investigated. The results show that the rate of crystal formation in the non-equilibrium dynamic cooling process of MgSO₄ saturated brine is related to the cooling rate. At the cooling rate of -1.02℃/min, MgSO₄ saturated brine can form MgSO₄·7H₂O crystal with a radial diameter of about 1300 μm after cooling for 30 min. However, when NaCl exists in brine, the final crystal form is MgSO₄·6H₂O, and most of them are irregular blocks. MgCl₂ in brine can promote the crystal to form prismatic MgSO₄·6H₂O. Under the action of NaCl and MgCl₂, MgSO₄-NaCl-MgCl₂ co-saturated brine can precipitate a complete crystal form of high-purity crystalline magnesium sulfate after cooling for 15 h. It is assumed that the initial crystal nucleus determines the crystal form, but the interference of Na⁺ on crystal growth makes the crystals diversified in morphology.

Magnesium hydroxide sulfate hydrate (MHSH-512) whiskers with one-dimensional structure were synthesized by sol-gel-hydrothermal method. The obtained MHSH-512 whiskers were characterized by XRD and SEM. The effects of Mg(OH)₂ precursor, the concentrations of Mg²⁺, \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} and Cl^- together with the hydrothermal conditions on the growth and morphology of MHSH-512 whiskers were systematically investigated. In addition, the growth mechanism of MHSH-512 whiskers before and after removal of Cl^- ions was also proposed. The results indicate that the freshly prepared Mg(OH)₂ gel with good dispersibility and high reactivity is liable to form [Mg(OH)₆]^4- during the subsequent dissolution and recrystallization under hydrothermal conditions. A moderate excess of \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} ions play an important role in the formation and growth of MHSH-512 whiskers. With a concentration ratio of c(Mg²⁺) to c(\mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}) of 3, MHSH nuclei can be formed between \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} and all the structural units [Mg(OH)₆]^4- by Mg-O-S bonds. Massive Cl^- ions in the solution may hinder the mutual interaction between OH^- and Mg²⁺ and delay the formation of [Mg(OH)₆]^4-. At the sametime, it competes with \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} on the surface of [Mg(OH)₆]^4-, which cause the whisker growth to lag, but has no substantial effect on the final morphology and dispersion of whiskers. Nevertheless, the influence of Cl^- on the morphology and dispersibility of the end product can be negligible. The synthesized whiskers exhibit excellent properties including high crystallinity and aspect ratio (150—200), smooth surface and good dispersibility. It has been determined that the optimal hydrothermal treatment is reacting at 190℃ for 10 h with c(Mg²⁺)/c(\mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}) of 3, which is easy to realize industrial-scale production of MHSH-512 whiskers. This research provides an effective approach for high-value utilization of magnesium resources in salt lake area of Qinghai.

In the salt lake area of Qinghai, China, large-scale utilization of bischofite generated by decades of potassium exploitation has been a big issue. This paper reports a base magnesium sulfate (BMS) porous sound-absorbing material prepared using BMS cement as matrix material, tetradecyl betaine (C₁₄BE) as air-entraining agent, and fly ash (FA) as mineral admixture. The effects of the concentrations of magnesium sulfate and C₁₄BE, together with the dosage of FA on the pore structure, compressive strength and acoustic performance of BMS porous materials were investigated as well. The results reveal that the concentrations of magnesium sulfate and C₁₄BE have significant impacts on the foamability and foam stability of the solution. The foaming is inhibited by highly concentrated MgSO₄ solution due to high viscosity and decrease in the solubility of C₁₄BE caused by a strong salting-out effect, whereas the foam stability is enhanced because of the remarkably increased surface tension and intermolecular force in the liquid film. The optimal concentrations of MgSO₄ and C₁₄BE are determined as 2.4 mol/L and 9.8 mmol/L, respectively, under which the prepared materials are possessing of large pore size, high open porosity, excellent acoustic and mechanical performances. The noise reduction coefficient (NRC) and compressive strength of the porous BMS sound-absorbing material reach as high as 0.70 and 2.0 MPa with a density of 309 kg/m³. In addition, FA doping can lead to a decrease in open porosity and pore wall thickening in the porous materials, which is harmful to the sound absorption performance. Nevertheless, the NRC value of the BMS porous material reaches 0.51 with a FA dosage of 40%, which can still meet the requirement of sound-absorbing materials used at highway, railway, etc. The development of BMS porous sound-absorbing materials not only provides a new type of inorganic non-metallic materials for the field of noise control, but also provides a new way for the effective utilization of salt lake magnesium resources.

Lithium resources are abundant in Qarhan Salt Lake in China. However, the overall grade is low, with the characteristics of low lithium concentration and high magnesium-lithium ratio, which makes development difficult. It has been proved that the adsorption method is effective for extracting lithium from brines with an ultrahigh Mg/Li ratio, especially, the lithium aluminum double layered hydroxides is the only adsorbent for industrial application relying on the advantage of elution without dissolution. In this work, the laboratory-made granulated adsorbent (C) and other adsorbents (A, B) that have been industrialized are evaluated to compare the adsorption performances. Through the characterization analysis of these adsorbents, the adsorbent C displays a good mechanical strength without dissolution or powder lose, declaring a great granulation process. The adsorption capacities of adsorbent A, B and C are 2.23 mg·g^-1, 0.45 mg·g^-1 and 4.90 mg·g^-1, respectively. All adsorption courses are in accordance with the pseudo-second-order kinetic equation. The fitting results of adsorption isotherms at different temperatures show that the Sips three-parameter model can describe the adsorption of the three adsorbents accurately.

Rb and Cs are important strategic resources. The effective separation of Rb and Cs from brine has been challenging work that has not been solved due to the complexity of the compositions in alkaline medium. For this purpose, a new supramolecular material BC6/XAD-7 or BC5/XAD-7 was prepared and characterized by vacuum impregnating and immobilizing BC6 or BC5 into the pores of mesoporous XAD-7 carrier. The adsorption of Rb, Cs and other typical metals on BC6/XAD-7 or BC5/XAD-7 was investigated by examining the influence of pH in aqueous phase and temperature. The adsorption kinetics of Rb and Cs onto BC6/XAD-7 and BC5/XAD-7 with the change of contact time was studied. The optimum adsorption conditions were obtained. The technical feasibility of the adsorption of Cs and Rb by the materials from a solution after K removal was confirmed. A technical process entitled CREC was proposed. It provides theoretical and experimental basis for the application of new supramolecular recognition materials in the adsorption and separation of cesium and rubidium in salt lake brine.

In order to search for high temperature heat transfer and thermal storage materials for solar thermal utilization, the phase diagram calculation method with branchs/regions separation was proposed, and two ternary eutectic mixtures of NaCl-CaCl₂-KCl and KCl-CaCl₂-MgCl₂ were designed. Based on the normal solution model, the phase diagrams of five boundary systems NaCl-CaCl₂,CaCl₂-MgCl₂,KCl-NaCl,KCl-CaCl₂, and KCl-MgCl₂ of the above two ternary systems were calculated with different interaction coefficients of different branches, and the complex phase diagrams containing compounds can be calculated by using the normal solution model. The calculated complex phase diagrams of KCl-CaCl₂, KCl-MgCl₂ systems and the other three systems without compounds were in good agreement with the experimental phase diagrams. Then, the phase diagrams of the ternary systems were calculated by sub region method based on the different interaction coefficients from the five boundary systems, and five new eutectic points of the ternary systems were predicted to guide the preparation of molten salt materials. The lowest eutectic point was verified by differential scanning calorimetry, and the lower limit of molten salt working temperature was determined. The working temperature range was determined by mass loss method. The results show that sodium potassium calcium and potassium magnesium calcium chloride molten salts can operate stably at 550—850℃ and 480—700℃, and can be used as high-temperature heat transfer and heat storage fluids.

A series of LiAl-CO₃-LDH/C hybrid composite precursors were prepared by a novel separate nucleation and aging steps we developed previously, glucose molecules were introduced as carbon source during the crystallization process of LDHs nuclei to fabricate LDHs/C hybrid composite precursor with controlled composition and structure. LiAl composite oxide based solid base catalyst with high specific surface area was obtained by topological transformation of precursors and removal of amorphous carbon components under high temperature treatment. Using XRD, FT-IR, BET, TEM, SEM, CO₂-TPD and other characterization methods, the composition, structure, texture properties and surface basicity of the catalyst were studied in detail. Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate was used as the probe reaction to investigate the alkali catalytic performance of the prepared catalyst. The results indicate that molar ratio of glucose to Al³⁺, hydrothermal temperature and calcination temperature are the main factors affecting the activity of catalysts, and higher hydrothermal temperature or calcination temperature has negative impact on the exposure of basic sites. The LiAl-MMO-150-3-500 catalyst, calcinated at 500℃ with the molar ratio of glucose to Al³⁺ was 3 in the corresponding precursor, has a surface area of about 229 m²·g^-1, the total basic sites of about 855 μmol·g^-1 based on phenol adsorption method, and thus exhibits the highest catalytic performance with the conversion of benzaldehyde reach up to 88.21% under our experimental conditions.

Light stabilizer 2-hydroxy-4-n-octoxy-benzophenone (UV-531) and sodium lauryl sulfate (SDS) co-intercalated MgAl layered double hydroxides (UV-SDS-LDH) was assembled by taking the advantages of the intermolecular forces between UV-531 and SDS in SDS-LDH which was prepared firstly through a co-precipitation and anion-exchange method. The crystal structure, composition, ultraviolet absorption and morphology of the obtained UV-SDS-LDH were characterized by XRD, FT-IR, UV-Vis and SEM, which demonstrated that UV-SDS-LDH with co-intercalating structure had strong ultraviolet absorption capability and nanosheet morphology. The intercalation significantly improved the resistance migration of UV-531 with the migration rate reduced from 83% to 50.5%. The addition of UV-SDS-LDH into polypropylene (PP) matrix markedly enhanced the thermal stability and resistance to photoaging of PP with the 50% mass loss temperature increasing from 411℃ to 441℃ and the photoaging index reducing from 65.9×10^-3 to 23.9×10^-3 due to its special structure and composition, suggesting the hopeful application of UV-SDS-LDH in the field of PP. This work offers a new method for the preparation of novel LDH based functional materials and the utilization of Mg resources in salt lakes.

The electrochemical intercalation/deintercalation method for lithium extraction from salt lake brine has the advantages of good selectivity, high extraction rate, and environmental friendliness, but the speed of lithium extraction is slow and the efficiency is low. In this paper, the kinetic study of the lithium extraction process is carried out to find out the control steps, and provide theoretical guidance for the optimization of the method. The influence of cell voltage, reaction temperature, lithium concentration, coating density and other factors on the lithium extraction rate was systematically studied, and the kinetic fitting analysis was carried out using the shrinking nucleus model. Compared with other factors, the cell voltage has a significant impact on the rate of lithium extraction. The speed-control step of the lithium extraction reaction showed a transition from chemical reaction control to shrinking nucleus model (the mass transfer of the solution to the inside of the electrode is the reaction limiting step) as the cell voltage increased. When the cell voltage is high (0.1 V), the calculated apparent activation energy of the reaction is 18.9 kJ/mol, the reaction order of lithium concentration is 0.382, the dependence coefficient of coating density is -1.46, and the corresponding reaction kinetic equation is established.

Due to the combination of low cost, good safety performance and high volumetric energy density (3832 A·h·L^-1), magnesium metal secondary batteries have received extensive attention. However, the practical application of magnesium anode is still limited by the lack of the solvation understanding of active species in electrolyte. At present, magnesium-based electrolytes are mainly divided into Grignard reagent electrolytes of ether solvents, magnesium-aluminum chloride complex (MACC) electrolytes and Mg(TFSI)₂-based electrolytes. Among them, the coordination environment of magnesium and chlorine plays a key role in the operation of magnesium battery, mainly involving reducing the deposition overpotential, enhancing the kinetics of magnesium deposition and improving the reversibility of magnesium deposition. Based on the specific magnesium-chlorine interaction in bulk electrolyte and at the electrode/electrolyte interface, we clarify the preliminary development route and design concept of magnesium-based electrolytes, and prospect the future research direction.

As an emerging membrane separation technology, nanofiltration has a potential application in separating magnesium and lithium from salt lake brine with a high magnesium-to-lithium mass ratio (Mg/Li). The separation of magnesium and lithium at different Mg/Li and cross-flow rates was evaluated and analysis on the mechanism in separation process was performed. The results showed that the membrane flux remained almost constant at different Mg/Li, the retention rates of magnesium and lithium and the separation efficiency decreased with increasing Mg/Li. When the cross-flow rate was 225 L/h, the retention rates of magnesium and lithium were 95% and -66%, respectively. In addition the Mg/Li in the permeate was reduced to 1.2. Study on the mechanism of mass transport for membrane process showed that magnesium was greatly influenced by dielectric exclusion, and steric hindrance. Nanofiltration shows considerable promise as a means to separate magnesium and lithium from salt lake brine with high magnesium-to-lithium mass ratios, which provides the basis for the subsequent preparation of high-purity lithium salt.

The phase equilibrium relationship of the ternary system CsCl-PEG8000-H₂O at 288.2, 298.2 and 308.2 K was studied by isothermal dissolution method and turbidimetric method. Meanwhile, the empirical equations were used to fit the data of binodal curve and tie line. Based on the experimental data, the completed phase diagrams at 288.2, 298.2 and 308.2 K were plotted. According to the experimental results, both solid-liquid equilibrium and liquid-liquid equilibrium coexisted in the ternary systems CsCl-PEG8000-H₂O at T = 288.2, 298.2 and 308.2 K. The corresponding phase diagrams at three temperature all composed of 6 regions: unsaturated liquid phase (L), two regions of one liquid and one solid phase CsCl (L+S), region of two-liquids phase (2L), two liquids with one solid CsCl (2L+S), and region of one liquid with two solids of CsCl and PEG8000 (L+2S). Comparing the phase diagrams CsCl-PEG8000-H₂O at T = 288.2, 298.2 and 308.2 K, it can be concluded that with the temperature increase, the areas of (L), (2L), (L+S) and (2L+S) increased, while the area of (2S+L) decreased. Comparing the phase diagrams CsCl-PEG1000/4000/6000/8000-H₂O at T = 288.2, 298.2 and 308.2 K, it can be found that there is only solid-liquid equilibrium in the ternary system CsCl-PEG1000-H₂O at 288.2 and 298.2 K, while the solid-liquid and liquid-liquid equilibria were found in the systems CsCl-PEG4000/6000/8000-H₂O at 288.2 and 298.2 K. Both solid-liquid and liquid-liquid equilibria were found in ternary systems CsCl-PEG1000/4000/6000/8000-H₂O at 308.2 K. And the region of two-liquids phase increase with the increase of molecular weight of PEG.

Doping Si atoms into crown ethers has the potential to greatly enhance their complexation ability to metal ions, but the regulation mechanism is still unclear. 12-Crown-4, 1,1-demethyl-1-sila-12-crown-4, 1,1,2,2-tetramethyl-1,2-disila-12-crown-4, 1,1,2,2,4,4,5,5-octamethyl-1,2,4,5-tetrasila-12-crown-4 and 1,1,2,2,7,7,8,8-octamethyl-1,2,7,8-tetrasila-12-crown-4 were selected as the models and the interactions between crown ethers and Li⁺ were deeply studied by quantum chemical density functional theory calculations. The results show that due to the increase of the O—Li⁺ coordination bond length, the covalent interactions of the 12-crown-4 with two or four Si atoms are slightly weaker, but the electrostatic interactions and dispersion interactions are stronger, and the Pauli repulsions are smaller, which ultimately lead to the stronger interaction between all the Si hetero12-crown-4 and Li⁺ than 12-crown-4. The above mentioned favorable factors stem from the fact that the electrons of the weakly electronegative Si in the Si—O bond are significantly polarized toward O, which enhances the advantage of O's negative electrostatic potential. Meanwhile, the complexion of Si hetero12-crown-4 with Li⁺ causes the —SiMe₂—SiMe₂— or —CH₂—SiMe₂— units to be away from Li⁺, effectively avoiding the Coulombic repulsion between Si—Li⁺. The crown ether-Li⁺ interaction mechanism revealed in this work will provide theoretical guidance for the future designing and synthesizing of heteroatom crown ethers with efficient extraction capabilities.

Solubility and refractive index in the ternary system CaCl₂-H₃BO₃-H₂O at 323.15 K were investigated with the dissolution equilibrium method. The phase diagram of this system consists of one invariant point, two univariant solubility curves and two single-salt crystallization regions for CaCl₂·6H₂O and H₃BO₃. The Pitzer parameters containing H₃BO₃ in the quinary system HCl-NaCl-CaCl₂-H₃BO₃-H₂O were fitted with the solubility data of ternary systems in this study and literatures. Combining the dissolution equilibrium constants of the solid phases in the quinary system, the Pitzer model of this system was constructed. The solubility in the quinary system and its subsystems were calculated with the Pitzer model. The phase diagrams and Pitzer model for the quaternary system were used to conduct computer simulation of H₃BO₃ separation from brine with NaCl and CaCl₂. The order of salt precipitation and changes in concentration of the brine were obtained. The calculation results show that the separation of H₃BO₃ is easier to achieve under acidic conditions.

Solid-liquid phase equilibria and phase diagrams for the quaternary system (Li⁺, Mg²⁺//Cl^-, borate–H₂O) were investigated, and the compositions in liquid phase, densities, refractive indices and pH were measured experimentally by using isothermal dissolution equilibrium method. There are five minerals corresponding to LiCl·H₂O, Li₂B₄O₇·3H₂O, MgCl₂·6H₂O, Mg₂B₆O₁₁·15H₂O, and the lithium carnallite LiCl·MgCl₂·7H₂O existed in this system. Mg₂B₆O₁₁·15H₂O occupies the greatest part of phase region, while LiCl·MgCl₂·7H₂O covers the smallest. The mineral LiCl·MgCl₂·7H₂O belongs to the incongruent double salt, and hungchaoite (MgB₄O₇·9H₂O) is transformed into Mg₂B₆O₁₁·15H₂O in the concentrated MgCl₂ aqueous solution. The crystalline area of inderite is the largest, indicating that magnesium borate is easy to crystallize, while the crystalline area of lithium carnallite is the smallest. The solubility of this quaternary system were predicted using Pitzer thermodynamics model, and the calculated solubility agreed well with experimental data. The phase equilibrium study of this quaternary system (Li⁺, Mg²⁺//Cl^-, borate-H₂O) will provide a theoretical basis to promote the development of lithium, magnesium and boron products and to guide the comprehensive utilization of this precious salt lake brine resources.

The isothermal solution equilibrium method was used to study the phase equilibrium of the quaternary system LiB₅O₈+ NaB₅O₈ + KB₅O₈ + H₂O at 298.15 K. The solid-liquid equilibrium solubility and physical properties (density and refractive index) of the system at 298.15 K were experimentally determined. Based on the experimental solubility, the dry salt phase diagram, water diagram and physical property composition diagram of the quaternary system were drawn. There are one invariant point (LiB₅O₈·5H₂O + NaB₅O₈·5H₂O + KB₅O₈·4H₂O), three univariant isothermal dissolution curves, and three crystallization zones corresponding to LiB₅O₈·5H₂O, NaB₅O₈·5H₂O, and KB₅O₈·4H₂O, respectively. It was found that neither double salt nor sold liquid was formed in this alkalis pentaborate system, and it belongs to the simple quaternary aqueous system. Based on the solubility data of sub-ternary systems, the single salt parameters and three-ion mixing parameters of the three pentaborates were obtained. The predictive solubility obtained by Pitzer and its extended HW model agrees well with the experimental values, indicating that the Pitzer parameters obtained in this work are reliable. The results of this study can provide the basic data of phase equilibria for the separation and purification of alkali-pentaborates.

For the heterogeneous catalysis process where the intrinsic reaction rate is fast, the macroscopic reaction rate is generally limited by the mass transfer rate. Based on the excellent mass transfer performance of HiGee technology and the breakthrough of key mechanical parts of HiGee equipment under high temperature and high pressure conditions, HiGee multiphase catalytic reactor (HMCR) gradually demonstrated great potential for the process intensification of heterogeneously catalytic reaction. This article mainly reviews recent researches on HMCRs in gas-liquid, gas-solid, and gas-liquid-solid systems, and the development prospects of HMCRs are also suggested.

The continuous growth of the global population has greatly increased the demand for meat, eggs and dairy products and other living products, as well as unprecedented challenges to the supply of traditional animal feed. Microorganisms are capable of utilizing carbon dioxide (CO₂), methane (CH₄) and other raw materials to synthesize single cell protein (SCP) with high protein content for feed or food processing. Bioconversion of CO₂ and CH₄ to produce SCP can not only expand the ways of protein production and alleviate the market demand, but also reduce the SCP cost and promote energy saving and emission reduction. In this review, the metabolic pathways of aerobic methanotroph and microalgae, bioconversion process, and bioreactor design are discussed based on the current research progress and literature of SCP synthesis and production. Finally, the economic feasibility of SCP production from greenhouse gases is preliminarily estimated and compared in order to evaluate the potential of commercial application.

The development of nuclear energy is an important measure for China's sustainable development. Lithium is an important energy strategy metal. The separation of lithium isotopes (⁶Li, ⁷Li) is a key technical problem that must be solved in nuclear energy development. It has received extensive attention from international and domestic scientists. It is a big challenge for the separation of lithium isotopes because of the similar extra-nucleus electronic structure of ⁶Li and ⁷Li. This paper reviews briefly the progress of ⁶Li/⁷Li separation by chemical exchange since the 1960s. The theoretical research as well as the new materials and medias developed for ⁶Li/⁷Li separation in the past five years are especially highlighted. Crown ether and its derivatives are the main chemical exchangers, but they have the drawback of poor binding performance with Li⁺, thereby low distribution coefficients of Li⁺. In view of this, the current researches on the enhancement of Li⁺ binding with crown ethers are summarized. The paper is expected to provide guidance for the development of new materials and systems for ⁶Li/⁷Li separation.

As the sole renewable carbon-containing resource, biomass can be converted into fuels and chemicals with high added value through thermochemical liquefaction. The lignocellulosic polyol liquefaction products with adjustable hydroxyl value and viscosity are abundant of active hydroxyl groups and have been extensively applied in polyurethane production. Due to the side reactions such as condensation and rearrangement during liquefaction, carbonyl compounds such as aldehydes, ketones, acids and esters are present in liquefaction products. The hydrogenation upgrading of liquefaction products over suitable catalyst is the necessary step to improve the quality of downstream polyurethane foam. In this paper, the technology, kinetics and mechanism of lignocellulosic polyol liquefaction were summarized. The selection of upgrading method and process technology of liquefaction products were elaborated. The new technology of “liquefaction coupling upgrading” was proposed, and the feasible suggestions for the future research focus and development trend were put forward.

Gallium(Ga) is widely used in semiconductor, catalysis, medical and other fields. With the vigorous development of the semiconductor industry, the increasing demand for Ga has prompted people to find new sources. Recycling Ga from coal fly ash can not only reduce environmental pollution, but also alleviate the growing demand for Ga. This review summarized the Ga occurrence in coal fly ash, leaching process and separation methods of Ga from coal fly ash. Meantime, this paper highlighted the current research status of solvent extraction and adsorption for the recovery of Ga from coal fly ash. The existing problems were discussed. Finally, the recovery of Ga resources from coal fly ash was prospected and the synergetic recovery of Ga and other multi elements from coal fly ash had been proposed.

The thermal dissociation process of natural gas hydrate is a Stefan phase change problem with moving boundaries. Based on the conservation integral heat conduction model of the single-phase continuous hydrate control body, the paper establishes the interface coupling Stefan energy conservation condition of the natural gas hydrate thermal decomposition control body considering the sharp moving boundary. Using Boltzmann's similar variables, the Neumann solution of the Stefan phase transition model for the thermal decomposition of half infinite natural gas hydrate was obtained. The monotonicity of the transcendental equation was proved, and the uniqueness of the Stefan model was confirmed. By example analysis, the monotonicity of the transcendental equation, and the uniqueness solution of Stefan model have been verified. By MATLAB programs, the laws of temperature distribution, dissociation frontal brim have been studied during the thermal dissociation process into a hydrate reservoir. The sensitivity fitting studies have shown that λ (the solution of transcendental equation) and x_f (interface position) increased gradually, x_d (the penetrated depth) and t_d (the penetrated time) decreased gradually with the temperature increasing.

Studying the thermophysical properties of new refrigerants is the basis of refrigerant substitution. Among the new environment-friendly HFO refrigerants, R1336mzz(E) has similar thermal properties to R245fa and is a promising alternative to R245fa in high temperature heat pumps and organic Rankine cycles. The liquid viscosity of R1336mzz(E) in the range of 278—333 K was measured by rotating capillary viscometer. Besides, we correlated the experimental data according to four liquid viscosity equations, and obtained the correlation equation between the viscosity of R1336mzz(E) and temperature. As a result, it illustrated that the modified nonlinear Andrade correlation equation had the highest correlation accuracy. Besides, its average absolute deviation (AAD) and maximum absolute deviation (MAD) were 0.170% and 0.311%, respectively. Based on the application prospect of R1336mzz(E) in high temperature heat pump, through the fitting of four viscosity correlations, the experimental data were extrapolated to the critical temperature (403.37 K). What's more, the modified nonlinear Andrade correlation extrapolation obtained the most reliable data according to the error analysis. Of course, it could be used as the viscosity data near the critical temperature of R1336mzz(E). We intended to provide basic data for the alternative application research of R1336mzz(E).

Silica-reinforced composites are important ablative thermal protection materials. In this paper, a new ablative analysis model of silica-reinforced composites was established based on the comprehensive considerations of a variety of physical and chemical reactions such as carbon-silicon dioxide reaction, carbon oxidation, erosion and evaporation of molten silicon dioxide. First, the concentration equations of gas species in the near wall area considering C-SiO₂ reaction were derived by using the mass conservation principle, chemical equilibrium law and saturated vapor pressure equation, and then based on the solution of equations under different temperature and pressure, the ratio of carbon reacting with silicon dioxide to total carbon consumption were calculated. Then the mass and energy conservation equations considering C-SiO₂ reaction were established. The model was used to calculate the ablation velocity of the material under different working conditions. The results showed that the simulation met the experimental data well, and the maximum absolute error of the ablation velocity was only 0.034 mm/s. Finally, the effect of resin content on the ablative properties of silica-reinforced composites was studied, and the results showed that the ablation performance was best when the resin content was about 0.5.

Microstructure coupled wettability control is currently the main method to enhance nucleate boiling heat transfer. In this work, the CFD-VOF three-dimensional numerical method is conducted to compare the influence of wettability modulation with time and space on bubble dynamics, phase interface deformation and heat transfer performance. The results show that the hydrophilicity increases the curvature and the resultant force at the bubble interface which promotes the departure of the bubble. Space modulation mainly increases the bubble volume, while the time modulation always optimizes the bubble dynamic and increases the proportion of the growth stage in the entire bubble cycle, leads to an obviously enhancement of heat transfer. Both the space gradient wettability modulation and the hydrophilicity improvement in growth stage can improve the heat transfer performance of single bubble boiling significantly, and the average heat flow increases by 42.7%. Considering the difficulty in manufacturing gradient wettability surfaces at micro-scale, time modulation wettability has a better development prospect in boiling heat transfer enhancement.

Loop heat pipes (LHP) have great application prospects in the cooling of electronic elements duo to their compactness and high efficiency. This paper designed a compact LHP with capillary core flat-over evaporator and investigated its start-up and heat transfer performance under various conditions experimentally. The results show that a higher heating power and higher refrigerant charge are beneficial with the LHP starts up stably, while it happens oscillation during the start-up process with low heat load and charge ratio. As for the heat transfer performance, there is an optimal refrigerant filling ratio corresponding to the heat load where the LHP shows the best cooling performance. The optimal filling ratio is small when the heat load is relatively low, and the performance will be better if the refrigerant charge is relatively large under a condition with high heat load.

The complexity of the industrial combustion environment makes it difficult for the traditional weighted-sum-of-gray-gases (WSGG) model to meet the accuracy requirements of gas radiation characteristics calculations. Based on HITEMP2010 database, the k-distribution method is introduced into WSGG model based on the rank correlated theory. Assuming that the participating gases are statistically uncorrelated, a WSGG model for gas mixture with arbitrary concentration and temperature distribution is established by superposition method. The radiation heat transfer of non-isothermal and non-homogeneous gas mixtures under four different combustion conditions is calculated. The effectiveness of the new model is verified by comparing the radiative heat flux and radiative source term calculated by the new model with line-by-line(LBL) and other models. The results show that the new model parameters can well predict the radiation characteristics of gas mixture under any conditions.

Co₃O₄/USY composite material was synthesized by a hydrothermal method. Experimental study was conducted to investigate its absorption and catalytic oxidation characteristics of organic pollutant toluene. Since the Co₃O₄ can be efficiently heated by microwaves, the heating characteristics and catalytic oxidation of toluene on Co₃O₄ modified USY under microwave action were also investigated, with an aim to discuss the feasibility of microwave-assisted rapid regeneration of adsorbent whilst in-situ degradation of organic matter. By hydrothermal reaction, Co₃O₄ forms a porous cellular structure on the surface of USY. The USY loaded with Co₃O₄ maintains high adsorption capacity, and the adsorption capacity of Co₃O₄/USY-1.5m at room temperature is 85 mg/g. The prepared Co₃O₄/USY composite material exhibits excellent catalytic oxidation properties, CO₂ selectivity and stability at 325℃ in both dry and wet conditions. The prepared Co₃O₄/USY composite material can couple with microwave in an efficient way, leading to quick start up its catalytic function. Comparative study shows that the CO₂ selectivity and catalysis stability under the microwave heating scenario are better than conventional heating when the reaction temperature is controlled at 250℃. The above results indicate that the prepared Co₃O₄/USY composite material can be used as an adsorbent to adsorb toluene and regenerated by microwave heating whilst the desorbed organic matter can be efficiently degraded by in situ catalytic oxidation.

The overall characteristics of structure evolution in the optimization of heat exchanger networks using random walk algorithm with compulsive evolution (RWCE) are studied by monitoring the optimization process of the heat exchanger units in the optimal structures. The results show that the heat exchanger units formed in the early stage turn to be impregnable, making it difficult to retain the newly generated units based on the local optimal structure and promote the global optimization. To solve the problem, this paper proposes a reconfiguration strategy of heat exchange units to enhance the ability of structural mutation for RWCE. First, the existing heat exchanger units in the optimal structure would be eliminated randomly to vacate the solution space for generating new units. Then, new heat exchange units with the same number of eliminated ones are reconfigured according to the constraint conditions, which can improve the structural diversity and expand the search domain. Meanwhile, combined with the indicator for monitoring optimization status, the mutation period is adjusted randomly to maintain high mutation activity and enhance the global optimization ability of the algorithm. The improved RWCE algorithm with the proposed strategy is applied to two cases and the mechanisms of the strategy are analyzed and summarized. The results obtained are better than those of the existing liferature, confirming the effectiveness of the strategy.

The hydrated salt phase change material has a wide range of application prospects in the field of medium and low temperature heat storage due to its high phase change enthalpy and low cost, but it usually has the problems of large subcooling and poor thermal cycle stability in the process of heat storage and release. Here, a modified magnesium nitrate hexahydrate is prepared as composite phase change material (PCM) for thermal energy storage, and the high-performance heat storage device using the modified PCM is designed and fabricated. The magnesium nitrate hexahydrate is modified by using calcium sulfate dihydrate as nucleating agent to synthesize composite PCM. The thermal properties and cycle thermal stability of the composite PCM are tested by differential scanning calorimeter (DSC) and thermal analysis method. Moreover, the composite PCM-based heat storage device and heating system with storage capacity of 152 kWh are designed and constructed, and their thermal performances are tested at different working conditions. The results show that the composite PCM with 2%(mass). Calcium sulfate dihydrate has good cycle thermal stability, and its supercooling degree can be kept within 0.5℃ after 50 melting-solidification cycles. The phase-change temperature is about 87℃ and the phase-change enthalpy is maintained above 150 kJ/kg. The PCM-based heat storage device achieves an average charging power up to 27 kW and discharging power of 8 kW. The thermal efficiency of heat storage-release is as high as 92.3%, and the heat storage device can ensure the outlet water temperature is higher than 56℃ during the heat release process, and thus can meet building heating and hot water.

Focusing on the air injection development mechanism of light and heavy oil reservoirs, typical light and heavy oil samples were selected for thermogravimetric experiments, and the thermal behavior and kinetics characteristics of crude oil at three oxidation stages were comparatively analyzed by the conversion method of Ozawa- Fynn-Wall, and the effect of surface effect on the oxidation reaction of light and heavy crude oil was also discussed. The results showed that: ①There is a transition zone between each oxidation stage, and the accurate selection of conversion rate is very important for kinetic parameters. ②The oxidation characteristics of light and heavy crude oil at different oxidation stages are obviously different. Light crude oil is mainly oxidized at low temperature, while fuel deposition and high temperature oxidation are not significant. Moreover, the initial temperature of low temperature oxidation, fuel deposition and high temperature oxidation stage of light oil is lower, which is more likely to induce oxidation reaction. Fuel deposition and high temperature oxidation of heavy oil are significant, and the oxidation reaction rate is faster. ③The surface area effect causes the low temperature oxidation activation energy of light oil to decrease by more than 15%, and the peak temperature decreases by 7—17℃. The deposition and high temperature oxidation of heavy oil fuels are significantly enhanced, and the burn-out temperature drops by 10—17℃.

Mastering the migration of valuable rare elements in coal during combustion is of great significance to the utilization of valuable elements in coal. Four coal samples with high aluminum content, coal slime, and two coal gangue samples were used in this work. The combine form of lithium (Li), gallium (Ga) and rare earth elements (REE) in these samples was analyzed using a stepwise chemical extraction method. We investigated the escape of Li, Ga, and REE during coal combustion between 300 and 1100℃ and their enrichment behavior in ash. The correlation between migration of rare elements and composition characteristics of coal samples was also discussed. The results showed that Li, Ga and REE in these coal samples were mainly in form of silicate. The escape ratio of these elements during coal combustion was negatively correlated with the ash content in coal, and positively correlated with volatile matter and carbon content. These elements are concentrated in different degrees in ash, and the enrichment efficiency of REE is higher than that of Li and Ga. The higher the content and volatile content of trace elements in the raw materials and the lower the ash content, the higher the content of trace elements in the ash obtained under the same combustion conditions.

Using a vertical tube furnace reactor combined with a low-pressure impactor particle collection device, the effects of corn stalk roasting mixed with ammonium dihydrogen phosphate (NH₄H₂PO₄) on the physical and chemical properties of roasted products and the emission of combustion particles in the fixed bed were studied. The results show that the corn stalk baking alone can effectively improve the quality of biomass, but also increase the emission of particulate matter. When baking at 300℃, PM₁, PM_1-2.5 and PM_2.5-10 increase by 76.5%, 194.8% and 170.2%, respectively. Studies have shown that the torrefied corn stalk with NH₄H₂PO₄ increased the ash content of solid products, but significantly reduced the O/C ratio of solid products and increased the ash-free heating value. In addition, blending NH₄H₂PO₄ can significantly increase the release rate of Cl during torrefaction and reduce the content of Cl in the solid product. Torrefaction with NH₄H₂PO₄ can effectively reduce the emission of particulate matter, especially PM₁, and the best effect is achieved when the mixing P/K molar ratio is 1, at this case, PM₁ reduces emissions by 28.8% compared to when no additive is added. Studies have shown that the introduction of NH₄H₂PO₄ in the biomass torrefaction can promote the removal of Cl and reduce the emission of fine particles in the subsequent combustion process.

The wide application of non-aqueous redox flow battery (NARFB) is restricted by its lower performance. Adding some metal ion additives to the electrolyte is a possible solution. In this study, the influence of Sb³⁺ ions on the electrochemical performance of non-aqueous redox flow batteries (NARFBs) was experimentally studied. The results showed that the electrochemical reaction kinetics of V(Ⅲ)/ V(Ⅱ) redox couple is enhanced by the addition of Sb³⁺ (up to 22.6%), the diffusion coefficient of vanadium ions also increases (up to 63.3%) and the charge transfer resistance decreases (up to 11.9%). The field emission scanning electron microscope shows that Sb ions are electrodeposited on the surface of graphite felt, which contributes a catalytic effect on the electrochemical reaction so as to improve the electrochemical performance. Due to the trade-off between the enhanced kinetics and reduced active surface area, the optimum concentration of Sb³⁺ ions is found to be 15 mmol·L^-1. In addition, the flow battery assembled with negative electrolyte containing Sb³⁺ ions exhibits 31.2% higher power density, from 3.08 mW·cm^-2 with pristine electrolyte, to 4.04 mW·cm^-2 with 15 mmol·L^-1 Sb³⁺ ions in the electrolyte. These results provide a convenient and promising method for improving the battery performance of NARFB.

An adsorbent with the advantages such as high utilization of amino group, stable structure and easy-to-handle operation was prepared to efficiently capture aquatic Cr(Ⅵ) by using the polyethyleneimine (PEI) as the modification reagent and the juncus (JC), a natural biomass with sponge-like structure, as the structure support. The PEI solution containing epichlorohydrin was firstly introduced into the JC and then the PEI was in-situ attached to JC fibers by the grafting reaction, resulting in a porous adsorbent (PEI-JC). The elemental analysis, SEM, FT-IR and XPS were employed to characterize the composition and structure of PEI-JC, as well as the adsorption mechanism of Cr(Ⅵ). The effects of PEI concentration, solution pH, initial concentration of Cr(Ⅵ) and coexisting compounds on the adsorption were studied. The results show that the maximum adsorption capacity of the Langmuir model of PEI_10.0-JC prepared from PEI with concentration of 10.0%(mass) is 474.6 mg·g^-1 at 30℃ and a pH of 2.0; PEI_10.0-JC could decrease the Cr(Ⅵ) in the solutions with different coexisting compounds from 10.0 mg·L^-1 to the value that is less than the emission standard of industrial wastewater of China (0.5 mg·L^-1); PEI_10.0-JC can be reused, and its structure has not changed significantly during the adsorption process; adsorption and reduction are the main mechanisms for PEI-JC to remove Cr (Ⅵ) from aqueous solutions.

Biomimetic modification is an important method to improve the antifouling performance of nanofiltration membranes. Choline chloride (ChC) was used to post-process the graphene quantum dots (GQDs-TMC) nanofiltration membrane to mimic the zwitterionic anti-pollution surface of phosphorylcholine on the cell membrane. Fourier transform infrared spectrometer (FTIR) and energy dispersive spectrometer (EDS) measurement showed that choline chloride molecules were covalently bonded to the separation layer of nanofiltration membrane. The degree of biomimetic modification would be enhanced by increasing the reaction temperature and the concentration of choline chloride solution. The quaternary ammonium groups of ChC forms zwitterionic structure with carboxyl groups in the separation layer of nanofiltration membranes, which improved the hydrophilicity of the biomimetic nanofiltration (GQDs/ChC-TMC) membranes, reduced the surface potential, improved the rejection ratios of dye molecules and divalent salt ions, and significantly enhanced the antifouling performance. After soaking in acid, alkali and oxidant solutions and high temperature separation experiments of nanofiltration membrane, the permeability and rejection ratio of GQDs/ChC-TMC nanofiltration membranes have not changed significantly. It indicated that the biomimetic nanofiltration membrane has excellent chemical stability and thermal stability.

Based on the particularity of the use environment of fluoroether rubber, from a physical and chemical point of view, the quality, mechanical properties, and chemical related parameters such as structure, element composition and thermal stability were studied, and the influence of aging temperature and aging time on the properties of fluoroether rubber was analyzed. The influence of temperature and aging time on the properties of fluoroether rubber is analyzed. The results show that: fluoroether rubber has excellent resistance to lubricating oil aging, and its physical and chemical properties remain stable during long-term aging in the temperature range of -25—200℃; When aging temperature reaches 200℃ and above, the swelling and oxidation reaction accelerate, the material will gradually change from soft and tough to hard and brittle with the aging time. Especially at the extremely high temperature of 225℃, dehydrofluorination reaction causes the fracture of C—F bonds, the content of F element significantly decreases. Meanwhile, the oxidation reaction is enhanced, forming the CO bonds, so that the content of O element increases; The quality, chemical structure and element content of fluoroether rubber basically remain unchanged at low aging temperatures, and glass transition occurred at -40℃, resulting in the reduction of mechanical properties.

To explore the oxidation characteristic of the alternative fuel propane/methanol mixture, the explosion limit was used to study the negative temperature coefficient (NTC) response characteristics of methanol to propane/oxygen mixture. The results show that the pressure of the lower turning points steadily increases with the increase of methanol mole fraction. The temperatures of the lower turning points show no noticeable variation. However, the methanol has almost no effect on the temperatures and pressures of upper turning points. In general, the NTC region is shrunken to high-pressure region with the increase of methanol mole fraction. In addition, the temperature, pressure and heat release rates of the main reactions profiles of the non-explosion, cool flame, and hot flame conditions, under different explosion scenarios are compared. Furthermore, to elucidate the key control mechanism, sensitivity analyses of the turning points are performed.

Research focus and fronts on organic photoelectric polymer materials was analized based on ESI database and CiteSpace analysis. Design and synthesis of high performance reactive layer materials, design and synthesis of high performance interface materials and investigation of their interface regulation performance, controllable doping of organic semiconductor active layer surface interface in battery devices, study on energy loss of active layer of organic solar cell, are the research hotspots of organic solar cells. The research fronts include high efficiency solar cells, non-fullerian dilute receptors, two dimensional conjugated polymers, ternary organic solar cells, transparent organic thin film transistors, structure-performance research, processing and application performance, etc.. Evolution trends in organic solar cell research frontiers is from polythiophene donor system to novel donor-acceptor system, from single layer heterojunction battery structure to bilayer to bulk heterojunction cell structure, from fullerene receptor to non-fullerene receptors, at last high efficiency and stability devices.