锂离子电池介观尺度光滑粒子水力学模型

针对锂离子电池内耦合电化学反应的多物理传输过程,采用光滑粒子水力学数值技术,开发了可以考虑电极(包括隔膜)介观微结构的数值模型.以电极中固体活性物颗粒尺寸为主要考虑参数,初步探讨了该模型用于电极介观微结构设计的可行性.模型模拟得到放电过程中电池内部Li/Li+浓度场、固/液相电势场以及交换流密度等微观细节分布,以及电池宏观性能如输出电压等,据此可以分析并揭示电池放电过程的基础物理化学机制、电池宏观性能与构成电极的固体活性物颗粒尺寸之间的关联.研究还发现:当阴、阳极固体活性物颗粒尺寸均较小时,固体活性物颗粒内部Li分布更为均匀,电化学反应更均匀发生,电池输出电压最高.

A Mesoscale Smoothed Particle Hydrodynamics Model for Lithium-Ion Batteries

We develop a model for the multi-disciplinary transport coupled electrochemical reaction processes in lithium-ion batteries via a smoothed particle hydrodynamics numerical approach. This model is based on a mesoscopic treatment to the micropore structures of electrodes. Focusing on the effects of solid active particle size, this work explores the feasibility of using this model for electrode microstructure design. The model results provide detailed distributive information of all the primary and participating parameters, including Li⁺ concentration in the electrolyte, Li concentration in solid active particles, solid/electrolyte phase potential, and transfer current density. Furthermore, macroscopic parameters such as the output voltage are also determined. Based on the simulation results, the underlying physicochemical fundamentals are analyzed and the relationships between the macroscopic performance of the battery and the size of solid active particles are revealed. The battery having the smallest solid active particles in both electrodes features a more uniform Li distribution inside the particles and a more uniform distribution of electrochemical reactions on the surface of each particle, leading to a higher output voltage.