The preparation of phosphorus-doped microcrystalline graphite and its electrochemical performance as an anode material for lithium-ion batteries

doi:10.11949/0438-1157.20241521

Abstract

Abstract:

Existing anode technology has reached its performance limit. As one of the most commonly used graphite materials in anode materials, microcrystalline graphite has not been fully developed in practical applications. Therefore, the development of anode materials with high energy density and fast charge and discharge capabilities has become a hot topic in the field of lithium-ion batteries. A hydrothermal synthesis method was ingeniously employed to successfully fabricate phosphorus-doped microcrystalline graphite anode materials. The surface of microcrystalline graphite was modified by phosphoric acid hydrothermal method, which achieved effective doping of phosphorus element and ensured the stable adhesion and uniform distribution of doping elements during high-temperature calcination. The results indicate that phosphorus doping markedly boosts the surface chemical activity of microcrystalline graphite, achieving an initial discharge specific capacity of 501.56 mAh/g. Furthermore, at a high current density of 3C, the discharge capacity sustains at 121.98 mAh/g, approximately triple that of the undoped material.

Key words: lithium-ion batteries, anode materials, microcrystalline graphite, phosphorus doping, electrochemistry

摘要：

现有的阳极技术已接近性能极限。微晶石墨作为阳极材料中常用的石墨类材料的一种，其在实际应用中的潜力尚未得到充分开发。开发具有高能量密度和快速充放电能力的负极材料已经成为锂离子电池领域的热点课题。采用一种简便且高效的水热合成法，通过高温煅烧，成功制备了磷掺杂的微晶石墨负极材料。通过磷酸水热法对微晶石墨进行表面改性，实现了磷元素的有效掺杂，并确保了在高温煅烧过程中掺杂元素的稳定附着和均匀分布。结果表明，磷掺杂能够显著提升微晶石墨的化学活性，初次放电比容量实现501.56 mAh/g，在3C高倍率的放电比容量仍保持在121.98 mAh/g，相较于原样提升了大约3倍。

关键词: 锂离子电池, 阳极材料, 微晶石墨, 磷掺杂, 电化学

CLC Number:

TM 912

Lixiao WU, Xixi YAN, Suna ZHANG, Yiming XU, Jiaying QIAN, Yongmin QIAO, Lijun WANG. The preparation of phosphorus-doped microcrystalline graphite and its electrochemical performance as an anode material for lithium-ion batteries[J]. CIESC Journal, 2025, 76(7): 3615-3625.

吴鹂霄, 燕溪溪, 张素娜, 徐一鸣, 钱佳颖, 乔永民, 王利军. 磷掺杂微晶石墨的制备及其在锂离子电池负极材料中的电化学性能研究[J]. 化工学报, 2025, 76(7): 3615-3625.

Figures/Tables 11

Fig.1 SEM images at 30 μm and 5 μm, and the EDS surface-scanning energy spectra of the C, O and P elements of MG and samples with different phosphoric acid contents

Fig.2 XRD and Raman spectra of MG and samples with different phosphoric acid contents

Table 1 （002） lattice spacing for MG and different phosphoric acid content samples

样品	λ/Å	2θ/(°)	晶格间距/nm
MG	0.15406	26.47204	0.33643
MG-HPO-2	0.15406	26.52727	0.33574
MG-HPO-3	0.15406	26.51931	0.33584
MG-HPO-4	0.15406	26.52919	0.33572
MG-HPO-5	0.15406	26.51398	0.33591
MG-HPO-6	0.15406	26.53285	0.33567

Fig.3 N2 adsorption and desorption isotherm curves and pore size distribution curves for MG and samples with different phosphoric acid contents

Fig.4 Thermogravimetric curves of MG and precursors with different phosphate contents under nitrogen atmosphere

Table 2 Content of element P in MG and samples with different phosphoric acid content

样品	P元素含量/%（质量分数）
MG	0
MG-HPO-2	2.630
MG-HPO-3	2.631
MG-HPO-4	4.963
MG-HPO-5	3.491
MG-HPO-6	2.847

Fig.5 SEM images and EDS surface scan energy spectra of P and F elements of samples with different phosphoric acid content after cycling

Table 3 Mass percentage of P and F elements in samples with different phosphoric acid content after cycling

样品	P元素含量/%（质量分数）	F元素含量/%（质量分数）
MG-HPO-2	2.0666	10.8394
MG-HPO-3	2.0666	10.8394
MG-HPO-4	5.2142	19.1342
MG-HPO-5	2.2969	11.4470
MG-HPO-6	2.2814	13.2386

Fig.6 Electrochemical characterization of MG and samples with different phosphoric acid contents

Fig.7 GITT curves of MG and different phosphoric acid content samples

Fig.8 CV curves and Nyquist impedance spectra for samples with different phosphoric acid contents

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