电解液添加剂对锂离子蓄电池循环性能的影响

为了改善锂离子蓄电池的循环性能 ,在EC/DEC/1.0mol/LLiClO4 电解液体系中加入微量添加剂苯甲醚。以Li金属和改性石墨为电极材料 ,循环性能测试结果表明 ,苯甲醚的加入 ,使电池的可逆比容量和充放电效率均得到提高 ,且可逆比容量的衰减速度减慢。用FTIR对首次离子嵌入过程结束后的石墨电极表面SEI(SolidElectrolyteInterface)进行组成分析 ,发现加入苯甲醚后 ,电极表面SEI中的RCO3Li含量明显减少 ,但Li2 CO3 基本不变 ,并发现有新的产物CH3OLi生成。根据以上分析结果 ,提出了苯甲醚对锂离子电池循环性能的影响机理 :在Li+嵌入石墨电极的初次过程中 ,苯甲醚和EC、DEC的还原分解产物RCO3Li发生基团交换反应 ,生成CH3OLi ,该产物能有效提高石墨电极表面SEI的稳定性 ,减少锂离子嵌入石墨过程中引起的溶剂分子共嵌入 ,从而改善电池的循环性能。

Effect of anisole as an additive in electrolyte on the cycle performance of lithium-ion rechargeable battery

In order to improve the cycle performance of lithium-ion rechargeable battery， a little of anisole was added in the electrolyte system of EC／DEC／1．0 mol*L－1 LiClO4， with improved graphite and Li as electrode materials． The cycle test results show that the introduction of trace anisole can promote specific capacity and cycling efficiency and can reduce the declining rate of the specific capacity． The surface analysis results indicated by FTIR show that the RCO3Li obviously in the SEI（Solid Electrolyte Interface）of the carbon electrode with the introduction of a trace of anisole， after the first intercalation of Li＋ into the carbon electrode． But the concentration of Li2CO3 remains nearly consistent and a new component， CH3OLi， is found in SEI． It can be concluded from these results that anisole reacts with the reduction product of EC and DEC， RCO3Li， in the first process of Li＋ intercalating into the carbon electrode． The obtained CH3OLi is helpful in building up a more effective and stable SEI of the carbon electrode， reducing the cointercalation of solvent molecular． All these contribute to the improvement of the cycle performance of lithium-ion battery．