A comprehensive numerical study on electrochemical-thermal models of a cylindrical lithium-ion battery during discharge process

Modelling the electrochemical and thermal behaviours of cylindrical lithium-ion batteries (LIBs) is complicated by their multi-unit jellyroll structure. To evaluate the accuracy of cylindrical LIB models, eight electrochemicalthermal models (ECT) with different levels of fidelity and dimensionality (from one-dimensional (1D) to threedimensional (3D) electrochemical and thermal models) are established for a Li[Ni8Co1Mn1]O2/graphite 18,650 type cylindrical LIB. The effect of different levels of model simplification on the predicted LIB thermal and electrochemical characteristics are compared under different discharge and cooling rates. Non-uniformity indexes are also introduced to compare the differences between the eight models for predicting electrochemical reactions and heat generation non-uniformity. The accuracy and computation time of different models are compared, and the applicable scope of different models is discussed comprehensively. Furthermore, the nonuniformity mechanism inside the battery are also analysed. The present work can be used to help other researchers select appropriate electrochemical thermal models under different applicable conditions and study the battery thermal management system.