采用电化学-量热法研究以LiNi0.5Co0.2Mn0.3O2为正极材料的锂离子电池在不同环境温度和充放电倍率下的热电化学性能.结果表明:环境温度和充放电倍率是影响电池比容量的重要因素,随着充放电倍率和环境温度的增加,电池比容量逐渐减小.在低倍率(0.2C下,电池充放电初始阶段的热流缓慢增大,且出现多个放热峰;而在较高倍率(0.5、1.0、2.0C)下,电池充放电初始阶段的热流快速增长,且充电和放电过程分别仅出现一个明显的放热峰.通过热电化学研究,可获得电池充放电过程的产热量、化学反应焓变(△rHm)以及化学反应熵变(△rSm)等热力学参数.
The electrochemical-calorimetric method was adopted to study the thermo-electrochemistry performance of lithium ion batteries in which LiNi0.sCo0.2Mn0.3O2 acted as cathode materials at different ambient temperatures and charge-discharge rates.The results show that the discharge specific capacity decreases with increasing the charge-discharge rates and ambient temperatures.At 0.2C,the heat flow of the batteries increase slowly and appear a plurality of exothermic peaks,but at higher charge-discharge rates (0.5,1.0 and 2.0C),the heat flow increases rapidly and only an exothermic peak appears at the charge and discharge stage,respectively.Through investigating the thermoelectrochemistry,a series of thermodynamic parameters of lithium ion batteries during charge-discharge process,such as the amount of heat,enthalpy change of chemical reaction (ΔrHm),entropy change of chemical reaction (ArSm),are achieved.