三元材料锂离子电池的多阶段恒流恒压快充

Multi-stage constant-current and constant-voltage rapid charging of ternary material Li-ion battery

锂离子电池多采取单阶段恒流恒压快速充电,容量衰减严重,并有析锂的风险。结合XRD、SEM、TEM、显微共焦拉曼(Raman)光谱等方法分析以LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)为正极活性物质软包装锂离子电池在单阶段和多阶段恒流恒压策略下的循环行为。经过600次循环后(电压3.80~4.35 V、电流0.60~1.50 C),采用多阶段恒流恒压快充方法的电池的循环容量保持率为94.24%,较单阶段提升了4.91个百分点,欧姆阻抗及电荷转移阻抗的增长率为21.05%和2.86%,对比单阶段循环后分别降低了26.32及3.11个百分点;三元正极材料的层状结构比单阶段完整,多阶段负极的石墨化度为0.061 7,比单阶段低0.028 2,析锂现象更轻微。多阶段恒流恒压充电在快充工况中的性能优势更加明显。

Li-ion battery has serious capacity degradation and the risk of lithium precipitation when using single-stage constant-current and constant-voltage fast charging.Combined with XRD,SEM,TEM and microscopic confocal Raman spectroscopy(Raman),the cycle behavior of pouch Li-ion battery using LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2(NCM523) as cathode active material under the strategies such as single-stage and multi-stage constant-current/voltage is analyzed.After 600 cycles(voltage 3.80-4.35 V,current 0.60-1.50 C),the cycle capacity retention of the batteries with multi-stage constant-current and constant-voltage fast charging method is 94.24%,which is 4.91 percentage poins higher than that of a single stage.The growth rates of Ohmic impedance and charge transfer impedance are 21.05% and 2.86%,which are 26.32 and 3.11 percentage points lower than that of a single-stage cycle;the ternary cathode material maintains high structural stability,the graphitization degree of reactive graphite anode material is 0.061 7,which is 0.028 2 lower than that of single stage,the lithium precipitation is slight.The performance advantage of multi-stage constant-current and constant-voltage charging in fast charging conditions is more obvious.