锂离子电池阶梯充电制式与循环衰减机制

Step charging system and cycle capacity fade mechanism of lithiumion battery

针对锂离子电池快充需求与循环寿命保持的矛盾,以三元/石墨体系锂离子电池为研究对象,依据其倍率充电特性和正极、负极材料相变特征,提出了一种阶梯充电制式。采用该制式,电芯可以完成30 min充电80%荷电状态(SOC)的快充目标,且经过800次阶梯充电循环后,电芯放电容量保持率≥91.99%。通过对比阶梯充电制式下,不同循环次数放电容量衰减,dV/dQ曲线的变化情况,确定电芯阶梯充电循环容量衰减原因主要为活性锂离子损失。

Aiming at the contradiction between fast charge demand and cycle life maintenance of lithium ion battery,taking NCM/graphite system lithium-ion batteries as the research object,a step charging system was proposed according to its rate charging characteristics and phase transformation characteristics of cathode and anode materials.The fast charging target of 80%SOC can be achieved in 30 min by using the system,and the discharge capacity retention of the cell is more than 91.99%after 800 cycles.By comparing the decay of discharge capacity and the change of dV/dQ curve under the step charging system with different cycle times,it is determined that the main reason for the capacity decay of the step charging cycle is the loss of active lithium ion.