摘要
分别以石墨和钛酸锂为负极活性物质,制备了尖晶石镍锰酸锂的32131型圆柱锂离子电池。石墨负极电池和钛酸锂负极电池容量分别为7.5 A·h和5.5 A·h,质量能量密度分别达到152 W·h/kg和81 W·h/kg。常温充放电循环测试结果表明,石墨和钛酸锂两种负极体系电池循环寿命将分别达到400次和1000次,这种循环寿命的差别主要体现在负极上,即正极材料中溶解的Mn在石墨负极表面沉积并持续催化SEI膜生成,减少了电池中可使用的活性Li+,进而导致电池寿命快速衰减;相比而言,钛酸锂负极表面不存在明显SEI,同时正极过量设计电池也使得钛酸锂体系电池的镍锰酸锂与电解液间的界面副反应低于石墨体系的负极过量设计电池。
Due to the high specific energy and good cycle ability, secondary lithium-ion batteries have been adapted as the main power source for portable electronics in the past two decades. Recently this technology has been extended into the fast growing electric vehicle market. However such application posts further needs of battery technology advancement, especially higher energy density to ectend the driving range of electric vehicles. The higher energy density in batteries can be achieved by improving specific capacity of active materials or by increasing the working potential of the cathode materials. Among various high-voltage cathode materials, the spinel LiNi0.5Mn1.5O4 has been investigated as a promising cathode material for Li-ion batteries with high energy density. In this paper, LiNi0.5Mn1.5O4 / graphite and LiNi0.5Mn1.5O4 / Li4Ti5O12 are manufactured as the 32131-type cells, which offer more practical and reliable cell data compared with laboratory size coin-cells. The cathode electrode composite is LiNi0.5Mn1.5O4 ： SP ： KS-6 ： PVDF = 91.0 ： 3.5 ： 1.0 ： 4.5, and the two anode electrodes are Li4Ti5O12 ： SP ： KS-6 ： PVDF = 90.0 ： 4.0 ： 1.0 ： 5.0 and graphite ： SP ： CMC = 93.2 ： 2.5 ： 4.3, respectively. The cells are 7.5Ah（152 W·h/kg） for LiNi0.5Mn1.5O4/graphite with N/P=1.1 and 5.5 A·h（81 W·h/kg） for LiNi0.5Mn1.5O4/Li4Ti5O12 with N/P=0.9. The capacity retention is 90.1% for LiNi0.5Mn1.5O4 /graphite after 250 cycles with 0.5 C charge/discharge rate at room temperature. For LiNi0.5Mn1.5O4 /Li4Ti5O12 cell, the capacity retention is 97.2% after 200 cycles with 1.0 C charge/1.5 C discharge rate at room temperature, the cycle performance is almost the same with LiNi0.5Mn1.5O4/Li half cell. Therefore, the difference of cycle performance seems to be depended on the anodes. The capacity fading of the LiNi0.5Mn1.5O4/graphite can be explained by the impact of Mn dissolution, and active Li^＋ loss in the full-cell system through continuous SEI formation（electrolyte reduction） prompted by Mn reduced on the surface of graphite. LiNi0.5Mn1.5O4/Li4Ti5O12 cell whose capacity is limited by Li4Ti5O12 anode showed almost no SEI and has better cycling performance.
出处
《储能科学与技术》
CAS
2014年第6期624-628,共5页
Energy Storage Science and Technology
基金
国家863计划项目(2012AA110407)
安徽省科技攻关项目(1301021011)
2014年中国留学人员科技活动择优资助项目
关键词
镍锰酸锂
高电压
循环寿命
失效机理
LiNi0.5Mn1.5O4
high voltage
cycling performance
failure mechanism
