The effect of the charging protocol on the cycle life of a Li-ion battery
The effect of the charging protocol on the cycle life of a Li-ion battery
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DOI：
10.1016/j.jpowsour.2006.06.040
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发表时间：
2006-10
影响因子：
9.2
通讯作者：
Shengbo Zhang
中科院分区：
文献类型：
--
作者：
Shengbo Zhang
使用三种方法研究了充电方案对商业18650锂离子电池循环寿命的影响：（1）恒流（CC）充电，（2）恒功率（CP）充电，和（3）多级恒流（MCC）充电。MCC充电由两个CC步骤组成，其以低电流开始以充电初始10%容量，随后是高电流充电，直到电池电压达到4.2V。分别使用这些方法，将电池充电至4.2V，然后恒压（CV）充电，直到电流下降至0.05C。结果表明，即使使用相同的充电速率，电池的循环寿命强烈依赖于充电协议。在这三种方法中，发现CC方法更适合于缓慢充电（0.5C），而CP方法更适合于快速充电（1C）。交流阻抗分析表明，在循环过程中的容量损失主要归因于电荷转移电阻的增加，作为一个结果，在两个电极的表面上的表面层的渐进增长。由于Li+离子的损失和表面层的相关生长，快速充电导致加速的容量衰减，这与阳极上的金属锂电镀和电解质-电极界面处的高极化有关。电池电化学分析表明，使用降低的电流分别充电至初始10%容量和接近充电结束时，有利于长循环寿命。
The effect of the charging protocol on the cycle life of a commercial 18650 Li-ion cell was studied using three methods: (1) constant current (CC) charging, (2) constant power (CP) charging, and (3) multistage constant current (MCC) charging. The MCC-charging consists of two CC steps, which starts with a low current to charge the initial 10% capacity followed by a high current charging until the cell voltage reaches 4.2V. Using these methods, respectively, the cell was charged to 4.2V followed by a constant voltage (CV) charging until the current declined to 0.05C. Results showed that the cycle life of the cell strongly depended on the charging protocol even if the same charging rate was used. Among these three methods, the CC-method was found to be more suitable for slow charging (0.5C) while the CP-method was better for fast charging (1C). Impedance analyses indicated that the capacity loss during cycling was mainly attributed to the increase of charge-transfer resistance as a result of the progressive growth of surface layers on the surface of two electrodes. Fast charging resulted in an accelerated capacity fading due to the loss of Li+ions and the related growth of a surface layer, which was associated with metallic lithium plating onto the anode and a high polarization at the electrolyte–electrode interface. Analyses of the cell electrochemistry showed that use of a reduced current to charge the initial 10% capacity and near the end of charge, respectively, was favorable for long cycle life.