Reliability Estimation of Commercial Na-NiCl2 Batteries Using Theoretical and Simulative Approaches

Sodium-Metal Halide batteries are a promising and cheap alternative to lithium-ion ones for stationary applications such as smart grids. However, the reliability of their elemental cell is low, and a battery composed of hundreds of cells could likely have several broken cells after a few working years. Luckily, the cell failure mechanisms are not destructive and convert the broken cell in an almost ideal short-circuit. A simulation platform to quantify the effects of the broken cells on the battery performance was developed in this work, and used to estimate the reliability of four different Sodium-Nickel Halide (Na – NiCl ₂ ) commercial batteries manufactured by FZSoNick. A theoretical approach is first provided to support the results obtained from the simulations. The study highlights the necessity to improve the power control system of the battery to maximize its usable energy and mitigate the performance degradation caused by the broken cells.