晶态Li_(12)Si_7锂离子电池负极材料的电化学性能研究  

Electrochemical Performance of Crystalline Li_(12)Si_7 as Anode Material for Lithium Ion Battery

作　　者：杨亚雄[1] 马瑞军[1] 高明霞[1] 潘洪革[1] 刘永锋[1] 

机构地区：[1]浙江大学材料科学与工程学院,硅材料国家重点实验室,浙江省电池新材料与应用技术研究重点实验室,浙江杭州310027

出　　处：《电化学》2016年第5期521-527,共7页Journal of Electrochemistry

基　　金：国家自然科学基金资助项目(No.51471152);教育部创新团队项目(IRT13037);青年拔尖人才支持计划资助

摘　　要：通过加热摩尔比为12：7的Li H/Si球磨混合物,避免了Li与Si之间巨大的熔点差异,成功制备了晶态Li_（12）Si_7合金,研究了其电化学性能和储锂机制.发现Li_（12）Si_7在0.02~0.6 V的嵌脱锂过程中,只发生晶胞体积的变化,而不产生相变,呈现出明显的固溶储锂机制.该固溶储锂机制的存在,有效抑制了Si基负极材料嵌脱锂过程中由于相变导致的体积效应,使得晶态Li_（12）Si_7在0.02~0.6 V电压范围内具有显著改善的电化学性能,其首次库伦效率高达100%,30次循环后的可逆容量保持率约为74%,分别优于相同条件下原始Si电极的55%和37%.Crystalline Li_（12）Si_7 is successfully synthesized by heating the mixture of Li H and Si with a molar ratio of 12：7, which avoids the huge difference of the melting points between Li and Si. The electrochemical performance and lithium storage mechanism of the as-prepared Li_（12）Si_7 are studied in this work. It is found that only a change in cell volume takes place without a phase change during the lithiation/delithiation of Li_（12）Si_7 at a voltage range of 0.02 ~ 0.6 V, exhibiting a solid-solution lithium storage mechanism. Such a lithium storage process effectively retards the volume effect caused by the phase change during lithiation/delithiation of Si-based anode. This induces significantly improved the electrochemical properties of crystalline Li_（12）Si_7 while cycling at 0.02 ~ 0.6 V. The first Coulombic efficiency of crystalline Li_（12）Si_7 is determined to be as high as 100%, and the capacity retention is 74% after 30 cycles, which are distinctly higher than those of Si anode（55% and 37%, respectively） under identical conditions.

关 键 词：锂离子电池 负极材料 锂硅合金 电化学性能 储锂机制 

分 类 号：TM912[电气工程—电力电子与电力传动]