压力脉冲化学气相渗透法热解炭包履尖晶石LiMn2O4  

Carbon costing modification of LiMn_2O_4

作　　者：王洪[1] 邓璋琼[1] 

机构地区：[1]绵阳师范学院化学与化学工程系

出　　处：《化工新型材料》2008年第9期37-38,55,共3页New Chemical Materials

基　　金：四川省教育厅重点项目基金(07ZA159)

摘　　要：对碳包复的尖晶石型锰酸锂的电化学性能进行了研究。采用压力脉冲气相渗透法对商用尖晶石锰酸锂(LiMn2O4)粉末进行表面包复。一层热解碳膜的包复,使LiMn2O4未包复的LiMn2O4比较,粒子间的导电性增加,使LiMn2O4的大电流放电性能增加。热解碳包复LiMn2O4后,碳作为一层保护膜,抑制了电解液和电极活性物间的反应,从而抑制了在电池的反复充放电过程中,电解液的不可逆分解和对锂离子的捕获作用及Mn在电解液中的溶解,所以大大的改善了电池的长期循环性能。采用CH4-N2的混合反应气时,CH4含量控制在30%左右较好;高于40%时,生成的碳膜中会形成较大量的纳米级微孔。Using the pressurc-pulsed chemical vapor infiltration technique, thin pyrocarbon films were coated on the surface of the LiMn204 particles. The rate capability of the coated LiMn204 was improved significantly. While as-received LiMn2O4 maintained only 5% of its maximum capacity at a 20C rate （2400mA/g）, the 2.31%C-coated LiMn2O4 main- tained more than 70% of capacity. The cycleability was improved obviously by pyrocarbon-coating, which would be attrib- uted to the formation of pyrocarbon film on the surface of LiMn2O4 particles, which can reduce the direct contact between LiMn204 and electrolyte and thus effectively suppressed the interaction between them. Pyrocarbon would cause the de- crease of irreversible reaction as decomposing the electrolytes and trapping lithium ions. The preferable CH4 concentration was about 30% for the effective deposition on/in the samples when the gas system CH4 N2 was used. There were micron scale pores in pyrocarbon layer when CH4 concentration of was higher than 40%.

关 键 词：锂离子电池 锰酸锂 尖晶石 热解碳包履 压力脉冲化学气相渗透 

分 类 号：O614.111[理学—无机化学]