Effect of parallel connection topology on air-cooled lithium-ion battery module: Inconsistency analysis and comprehensive evaluation

The performance of lithium-ion battery modules is highly dependent not only on the thermal management system, but also on the connection design in module formation. Herein, we analyze the cell-to-cell inconsistency and evaluate the comprehensive performance of the air-cooled battery modules with different parallel connection topologies. Three types of connection topologies are investigated in this paper, the positive and negative terminals of which are arranged as: both at the air-inlet end (TOP-inlet), both at the air-outlet end (TOP-outlet) and one at each end (TOP-cross). First, a multi-physics model is introduced to describe the electrochemical, ageing, electrical and thermal characteristics of the module, and the model is thoroughly verified at the single-cell and multi-cell levels. Second, the different connected modules are simulated under benchmark configuration to analyze the cell-to-cell inconsistencies in terms of current, temperature and ageing. Next, a parametric study is performed by varying the air velocity, cell spacing and interconnect resistance of the modules. Six performance indexes are extracted from the simulation results to represent the module performance in different aspects. Finally, the three parallel connection topologies are evaluated comprehensively, demonstrating that TOP-cross is clearly superior to the other two. As compared to TOP-inlet and TOP-outlet, the comprehensive score of TOP-cross is improved by 22.9% and 13.7% respectively.