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针对锡负极材料充放电过程中的体积效应,本文综合采用组分改性与结构改性的研究方法,合成Sn-Cu合金负极材料,研究Cu的掺入对Sn电化学稳定性的影响,同时基于优化改性的Sn-Cu合金开展核壳结构设计,研究最佳核壳结构构造工艺.结果表明,掺入Cu能在一定程度上改善Sn的循环稳定性,Sn-Cu样品的容量在60周循环后趋于稳定,库伦效率较高;核壳结构处理能大幅提升Sn-Cu合金负极材料的循环稳定性,采用球形改性天然石墨(d50=15μm)作为内核的样品首次放电比容量接近800 m Ah/g,充电比容量最大值超过了500m Ah/g,100周容量保持率大于85%,最佳的核壳结构构造工艺是使用片状石墨作为内核,内核粒径为d50=15μm,外壳厚度为柠檬酸裂解碳占复合材料质量比的20%(质量分数).核壳结构能将Sn-Cu合金的体积效应控制在“囚笼”式结构内,利于材料容量的发挥及循环稳定性的提升.核壳结构的可控制备对实现锡基合金负极材料的产业化具有重要的作用.
In view of the volume effect during the charge and discharge of tin anode material, we synthesized the anode material of Sn-Cu alloy by using the research methods of component modification and structural modification, and studied the influence of Cu doping on the electrochemical stability of Sn. Meanwhile, Based on the optimized Sn-Cu alloy core-shell structure design, the best structure of the core-shell structure was studied.The results show that the incorporation of Cu can improve the cycling stability of Sn to some extent, the capacity of Sn-Cu sample is about 60 The cycle stability tends to be higher and the coulombic efficiency is higher. The core-shell structure treatment can significantly improve the cycle stability of the Sn-Cu alloy anode material. The first discharge specific capacity of the spherical modified natural graphite (d50 = 15μm) 800 mAh / g, the maximum specific charging capacity exceeds 500mAh / g, and the capacity retention rate at 100 weeks is more than 85%. The best core-shell structure construction process uses flake graphite as the core and the core diameter d50 = 15μm , And the thickness of the shell is 20% (mass fraction) of citric acid cracked carbon in the mass ratio of the composite material. The core-shell structure can control the volume effect of the Sn-Cu alloy in a “cage” type structure, Stability improvement. Core-shell structure Preparing a controllably important role in the realization of a tin-based alloy industry negative electrode material.