Influence of Parameter Differences on the Current Distribution Within Parallel-connected Liquid Metal Batteries

Liquid metal batteries (LMBs) have the advantages of low cost and long life, which are especially suitable for static energy storage in power grids. Understanding the relationship between inconsistent parameter distributions, topological connections, and battery module performance is important for designing and optimization of battery packs. This paper investigates the effect of differences in cell parameters and module design parameters on the current distribution in parallel LMB modules. Based on the equivalent circuit model (ECM), a parallel module with a Z-shaped topology is built and configured as a reference model that can be invoked in an interactive manner. The analytical solution of the current distribution is deduced under the assumption of identical cells within the module, the results revealed that the effect of the interconnection resistance on the current distribution depends mainly on its ratio to battery resistance. Design of experiments (DOE) is used to design 81 sets of experiments with the distribution dispersion of battery SOC and current as response variables and four parameters of capacity difference, internal resistance difference, interconnected resistance, and the number of parallel cells as factors, and $10^{2}$ Monte Carlo simulations are performed on the referenced model in each set of experiments to obtains highly reliable distribution results. The results module structural parameters are the main factors influencing differences in cell current distribution and an appropriate range of cell inconsistency has a positive effect on parallel modules. This research will provide a reference basis for LMB module design to reduce the inconsistency of batteries within the module.