电极孔隙结构对锂空气电池性能影响机制研究

Influence Mechanism of Electrode Pore Structure on Performance of Lithium Air Battery

以非水系锂空气电池为例,基于Comsol软件平台开发了一维电化学模型,该模型较文献中的模型计算结果更加接近实验测试结果。利用该模型探讨了空气电极孔隙率及其分布、制备空气电极固体骨架所用多孔碳颗粒尺寸、空气电极固体骨架和孔相扭曲率对非水系锂空气电池性能的影响规律,发现随着空气电极孔隙率增大,由其制备而成的非水系锂空气电池放电电压平台和容量越高;若沿着厚度方向的空气电极孔隙率随机,且其平均孔隙率与具有恒定孔隙率的空气电极孔隙率相同,则相对于后者,由前者制备而成非水系锂空气电池放电电压平台和容量更高;随着构筑空气电极固体骨架的多孔碳颗粒尺寸不断减小,非水系锂空气电池放电平台不断升高,但放电容量却不断降低;随着空气电极孔相或固体骨架扭曲率的逐渐增大,非水系锂空气电池放电平台和容量均呈不断降低的趋势。

The pore structure of air electrode has an important effect on the performance of lithium air battery.Therefore, based on the Comsol software platform, this paper developed a one-dimensional nonaqueous lithium air battery electrochemical model, and found that the simulation results by the present model are closer to the experimental results than those by the previously published model. What is more, the present model is widely used to investigate the effect of the air electrode porosity and its distribution, the particle size of porous carbon used to make the solid skeleton of air electrode, solid skeleton and pore phase tortuosity on the performance of lithium air batteries. The simulation results show that the air electrode porosity increasing, the discharge voltage platform and the capacity of nonaqueous lithium air battery increase. If the average porosity of the air electrode with the randomly porosity along the thickness direction is the same as the air electrode with the constant porosity, the discharge voltage platform and the capacity of the nonaqueous lithium air battery prepared by the air electrode with the randomly porosity are higher than the air electrode with the constant porosity. The results also show that the particle size of porous carbon decreasing, the discharge voltage platform of the nonaqueous lithium air battery increase, but the discharge capacity decrease. The solid skeleton and pore phase tortuosity increasing,the discharge platform and the capacity of nonaqueous lithium air battery decrease.