Effect of overdischarge (overlithiation) on electrochemical properties of LiMn2O4 samples of different origin
Effect of overdischarge (overlithiation) on electrochemical properties of LiMn2O4 samples of different origin
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DOI：
10.1007/s10008-017-3671-7
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发表时间：
2017-11-01
影响因子：
2.5
通讯作者：
Kirillov, S. A.
中科院分区：
文献类型：
--
作者：
Kosilov, V. V.;Potapenko, A. V.;Kirillov, S. A.
锂离子电池的过放电对电池的安全性和可靠性构成了严重威胁。本文研究了过放电(过锂)对不同来源锂锰尖晶石电化学参数的影响。在推荐的和更低的电位范围内进行240次循环的充放电测试。通过降低锂离子对Li/Li+的电位至+2.4或+1.5V将锂离子插入尖晶石，形成过锂尖晶石相Li2-xMn2O4。涉及低电位区的重复循环会恶化电化学参数：电池电阻增加，比容量降低。对于纳米尺寸的自制样品和微米尺寸的EQ-LibLMO(MTI)样品，即使是很小的过放电似乎也是完全不可接受的。微小尺寸的Be-30(NEI)样品在较低的电位下更能耐受循环。抗过放电能力最强的是铝掺杂的微米级HPM-9051C(TODA)样品。在较低的电压下处理，这种材料获得了一种稳定的趋势，比容量增加了一半。这可能意味着至少一半克当量的额外锂离子可以被电化学插入到尖晶石结构中的16个空洞中，从而得到Li1.5Mn2O4化合物，它能够在2.4-4.6V的电势范围内可逆地工作。
Overdischarge poses a significant threat to the safety and reliability of lithium ion batteries. In this paper, overdischarge (overlithiation) effect on electrochemical parameters of lithium manganese spinels of different origin is studied. Charge/discharge tests for 240 cycles are performed within recommended and lowered potential ranges. Insertion of lithium ions into spinels by decreasing potential to either +2.4 or +1.5 V against Li/Li+ is found to lead to the formation of the overlithiated Li2-xMn2O4 spinel phase. Repeated cycling involving the low-potential regions worsens electrochemical parameters: cell resistance increases and specific capacity decreases. It appears that even small overdischarge is totally unacceptable for the nanosized home-made samples and microsized EQ-LibLMO (MTI) samples. The microsized BE-30 (NEI) sample better tolerates cycling at lowered potentials. The greatest resistance to overdischarge demonstrates the aluminumdoped microsized HPM-9051C (Toda) sample. Being treated at lowered voltages, this material acquires a steady trend towards an increase in specific capacity by half. This may signify that at least half of the gram equivalent of extra lithium ions can be electrochemically inserted into the 16. voids in the spinel structure resulting in the Li1.5Mn2O4 compound, which is able to reversibly work within the 2.4-4.6 V potential range.