【摘要】 研究了在锂离子电池尖晶石LiMn2 O4 正极材料上包覆Al2 O3来改善材料在循环过程中的容量衰减问题。通过SEM和X射线衍射研究材料的表观形貌和晶体结构 ,在电化学性能测试中 ,发现包覆Al2 O3可以减少材料与电解液的直接接触 ,阻止了电解液对尖晶石的侵蚀 ,抑制锰离子在电解液中的溶解和由此带来材料结构的改变 ,以及与电解液中微量的HF反应 ,避免了HF对锰离子溶解的加速作用。从电化学循环测试后材料的X射线图谱上可以发现 ,LiMn2 O4 材料包覆Al2 O3后 ,可以在很大程度上抑制循环过程中Mn5O8杂相峰的出现更多还原

【Abstract】 In order to improve the structural stability of the LiMn 2O 4 as cathode materials of lithium ion batteries during cycling, spinel type LiMn 2O 4 was coated with a thin layer of Al 2O 3 on its surface. SEM, XRD and electrochemical test were used to investigate the surface morphology, structure and electrochemical properties of the Al 2O 3 coated LiMn 2O 4. The result shows that the layer of Al 2O 3 can reduce the solution of Mn in the electrolyte, which caused by the contact of LiMn 2O 4 with electrolyte. The layer of Al 2O 3 can also trap the trace HF in electrolyte, which drastically increases the dissolution of Mn cations through a disproportionation reaction of Mn 3+ . However, excessive Al 2O 3 will form a barrier for the extraction and insertion of Li +.更多还原