物理化学学报 >> 2008, Vol. 24 >> Issue (01): 165-170.doi: 10.3866/PKU.WHXB20080130

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LiNi0.5Mn1.5O4-xFx高电压电极高温保存下的电化学行为

杜国栋; 努丽燕娜; 冯真真; 王久林; 杨军   

  1. 上海交通大学化学化工学院, 上海 200240
  • 收稿日期:2007-07-02 修回日期:2007-09-03 发布日期:2008-01-05
  • 通讯作者: 杨军 E-mail:yangj723@sjtu.edu.cn

Electrochemical Behavior of High-Voltage LiNi0.5Mn1.5O4-xFx Electrodes at Elevated Storage Temperature

DU Guo-Dong; NULI Yan-Na; FENG Zhen-Zhen; WANG Jiu-Lin; YANG Jun

  

  1. School of Chemistry and Chemical Engineering, Shanghai JiaoTong University, Shanghai 200240, P. R. China
  • Received:2007-07-02 Revised:2007-09-03 Published:2008-01-05
  • Contact: YANG Jun E-mail:yangj723@sjtu.edu.cn

摘要: 采用溶胶-凝胶法结合高温热处理制备了锂离子电池用5 V正极材料LiNi0.5Mn1.5O4-xFx(x=0, 0.1). 通过X射线衍射(XRD)、扫描电子显微镜(SEM)和低温氮吸附法(BET)表征了粉体材料的结构、表面形貌和比表面特性, 并以其为正极材料装配电池后, 在85 ℃下高温保存24 h, 测量了保存前后电池的一系列电化学性质变化. 结果表明, 高温保存时电池开路电压会因自放电而较快地下降. 材料的比表面积和氟掺杂显著地影响电池的电压保持能力. 比表面积愈大, 电压保持时间愈短. 氟掺杂有利于提高电池在高温条件下的电压稳定性, 并可以改善电极与电解液之间的界面性质,使充放电性能更好.

关键词: 氟掺杂, 5 V正极材料, 高温保存, 二次锂电池

Abstract: 5 V cathode materials LiNi0.5Mn1.5O4-xFx (x=0, 0.1) for lithium ion battery were synthesized via sol-gel method combined with high temperature treatment. The synthesized samples were characterized by X-ray diffractrometry (XRD), scanning electron microscopy (SEM) and specific surface area measurements (BET). Coin cells were assembled using these cathode materials, followed by storage at an elevated temperature (85 ℃) for 24 h, and then a series of electrochemical measurements were conducted to examine the changes of the electrochemical properties before and after cell storage at the elevated temperature. The experimental results showed that the open-circuit voltage of the cell declined quickly during high temperature storage because of self-discharge. The voltage retention was significantly influenced by specific surface area of the powder material and fluorine doping. The larger the specific surface area is, the shorter the voltage retention time becomes. Fluorine doping was favorable for stabilizing the cell voltage at elevated storage temperature and could improve the interfacial property between the electrode and electrolyte. Therefore, the charge and discharge performance was enhanced.

Key words: Fluorine doping, 5 V cathode material, High temperature storage, Secondary lithiumbattery

MSC2000: 

  • O646