Abstract:

Lithium-sulfur batteries have received extensive attention in recent years due to the high specific energy. However, their development needs to overcome many problems such as the shuttle effect of intermediate products, the insulation of sulfur, and the volume expansion of the cathode. To effectively suppress the shuttle effect, this paper uses a method derived from Prussian blue analogs to synthesize a spinel bimetallic sulfide CuCo₂S₄ and use it for the cathode of lithium-sulfur batteries. XRD, SEM, TEM, BET, XPS and other characterizations were used to analyze the crystal structure and morphology of the synthesized materials, and the electrochemical performance of the CuCo₂S₄-S composite cathode was tested by cyclic voltammetry and galvanostatic charge and discharge process. Studies show that the CuCo₂S₄-S cathode exhibits excellent electrochemical performance. The first initial capacity is 959 mA·h·g^-1 at the rate of 0.2C, and 591 mA·h·g^-1 remains after 100 cycles. The high discharge specific capacity and good cycling stability are attributed to the hollow structure inside the CuCo₂S₄ material that can accommodate the active material sulfur and play a role in physical confinement; at the same time, the polar CuCo₂S₄ can effectively chemically adsorb polysulfides and suppress capacity loss caused by the shuttle effect of polysulfides.

Key words: nanomaterials, adsorption, synthesis, Li-S battery, bimetallic sulfide, spinel structure, hollow

摘要：

锂硫电池因较高的比能量近年来得到了广泛的关注，然而其发展需要克服中间产物的穿梭效应、硫的绝缘性和正极体积膨胀等诸多问题。为了有效抑制穿梭效应，采用普鲁士蓝类似物衍生的方法合成了一种尖晶石结构的双金属硫化物CuCo₂S₄，并将其用于锂硫电池正极。利用XRD、SEM、TEM、BET、XPS等手段对合成的材料的晶体结构、形貌等性质进行分析，采用循环伏安法及恒流充放电对CuCo₂S₄-S复合正极的电化学性能进行测试。研究表明，CuCo₂S₄-S正极展现出优异的电化学性能，在0.2C倍率下首次放电容量为959 mA·h·g^-1，经过100个循环后容量保持在591 mA·h·g^-1。较高的放电比容量和良好的循环稳定性归因于CuCo₂S₄材料内部的中空结构可容纳活性物质硫，并起到物理限域作用；同时，极性CuCo₂S₄可有效地化学吸附多硫化物，抑制多硫化物的穿梭效应造成的容量损失。

关键词: 纳米材料, 吸附, 合成, 锂硫电池, 双金属硫化物, 尖晶石结构, 中空