【作者】 张建斌；

【导师】 杨绍斌；

【作者基本信息】 辽宁工程技术大学 ， 材料学， 2011， 硕士

【摘要】 商业化的锂离子电池多以碳作为负极材料。但是随着人们对电池容量要求的不断提高,商业化的电池已经不能满足人们的需求。而Sn基具有比容量高、安全性能好等特点,使得它成为了人们研究的热点。在Sn基引入Co可以提高循环性能,本文以不同的Co源和Sn粉、炭黑为原料,采用不同温度固相烧结后球磨的方法制备锂离子电池负极锡钴碳复合材料,并采用XRD,SEM对复合材料进行了表征,并对材料的电性能进行了测试。在SnCo_x/C（Co_x=Co₃O₄、CoC₂O₄、CoCO₃）,600℃固相烧结体系中,XRD分析发现,SnCo₃O₄/C体系的主相为SnO₂,SnCoC₂O₄/C体系的主相为SnO₂和Sn,SnCoCO₃/C体系的主相为Sn。电化学分析表明,当钴化合物为CoCO₃时,制备的SnCoCO₃/C复合材料的首次脱锂比容量为257mAh/g,首次充放电效率为71.8%,循环25次后容量保持率为65.76%。由于SnCoCO₃/C样品具有较高的可逆容量和最佳的循环性能,因此本文优选在SnCoCO₃/C材料中添加单质Co,以考察单质Co对材料的结构和电性能的影响规律。在Sn（CoCO₃）_yCo_1-y/C（y=1、0.75、0.5、0.25、0.125、0.0625、0）,850℃固相烧结体系中,XRD分析发现Sn（CoCO₃）_yCo_1-y/C体系的7个样品的主相都是CoSn相。并且他们的主相的晶粒尺寸都小于100nm,均属于纳米晶复合材料。电性能分析发现,随着CoCO₃在样品中的摩尔含量的增加,Sn（CoCO₃）_yCo_1-y/C样品的首次充放电效率呈现逐渐增加的趋势,SnCoCO₃/C最大,达到了64%。随着单质Co在样品中的摩尔含量的增加,Sn（CoCO₃）_yCo_1-y/C样品的循环性能呈现逐渐增加的趋势,SnCo/C的循环性能最优,为79.3%。Sn（CoCO₃）_0.75Co_0.25/C的首次放电容量为297mAh/g,循环25次容量保持率为60%,具有优秀可逆性和较好的循环性更多还原

【Abstract】 Commercialized Li-ion battery used carbon as the anode materials. But with the demand of people improving, commercialized battery has not met the demand of people. Sn has the high capacity and the good safety performance, which make it become the focus of research.The introduction of Co in the Sn-based can improve cycling performance. The SnCo/C composites as anode materials for lithium-ion batteries were synthesized from different Cobalt,Sn powders and carbon black using solid-state sintering at different temperatures firstly and then ball milling.The characterization of the composite was carried out by XRD,SEM and electricalproperties measurement.In SnCo_x/C（Co_x=Co₃O₄、CoC₂O₄、CoCO₃） system using solid-state sintering at 600 temperatures,XRD analyses reveal that the main phase of SnCo₃O₄/C system is SnO₂, the main phase of SnCo₃O₄/C system are SnO₂ and Sn, the main phase of SnCoCO₃/C system is Sn. Electrochemical analysis shows that the first lithium deintercalation capacity of the composite when Co Compounds selected CoCO₃ was 257mAh/g and initial charge-discharge efficiency was 71.8%,The capacity retention achieved 65.76% after 25 cycles.Element Co is added into SnCoCO₃/C sample because of its higher capacity and best cycle performance,and study the influence of element Co on structures and electrochemcial performance of material.In Sn（CoCO₃）_yCo_1-y/C（y=1、0.75、0.5、0.25、0.125、0.0625、0） system using solid-state sintering at 850 temperatures,XRD analysis showed that the main phase of all the Sn（CoCO₃）_yCo_1-y/C is CoSn. And the grain size of Sn（CoCO₃）_yCo_1-y/C composites are less than 100nm,belong to nanocrystalline composite.Electrochemical analysis shows that with the molar mass of CoCO₃ is increased, the first charge-discharge efficiency of Sn（CoCO₃）_yCo_1-y/C samples is improved,SnCoCO₃/C sample reaches to the maximum,the first charge-discharge efficiency is 64%.With the increasing of molar mass of elemental Co,the cycle performance of Sn（CoCO₃）_yCo_1-y/C samples is improved,SnCo/C sample reaches to the maximum,reaching 79.3%.The initial discharge capacity of Sn（CoCO₃）_0.75Co_0.25/C is 297mAh/g, The capacity retention achieved 60% after 25 cycles,It had good capacity and best cycle performance.更多还原