Reveal the internal heat transfer of sodium ion batteries under nail penetration thermal runaway
The thermal safety of sodium-ion batteries under mechanical abuse is a key bottleneck for large-scale energy storage applications. In this paper, nail penetration tests were conducted on a 170 Ah prismatic sodium-ion battery at different states of charge, and simulations were performed to investigate TR and internal heat transfer within a multi-jellyroll structure. The simulations were based on the Domain-Based Ordinary Differential Equations interface in the Heat Transfer and Mathematics modules of COMSOL Multiphysics®: Each of the four jellyrolls was divided into three regions: core layer, middle layer, and outer layer. Joule heating from an ISC was applied to the core layer as a time-varying heat source, and the concentration of side reactions was solved using domain-dependent ordinary differential equations, then converted into a heat source via the Arrhenius equation. The simulations accounted for anisotropic heat conduction, thermal resistance layers between jellyrolls, and convective boundaries, and were validated through mesh-independence tests and experiments at 0% and 75% SOC. Simulations show that heat from ISC is concentrated in the first two jellyrolls, and the transition from net heat absorption to net heat dissipation occurs earlier—at 48 s at 75% SOC compared to 470 s at 0% SOC. The study reveals the patterns of non-uniform heat transfer within multi-core sodium batteries, which can support safety design and early warning systems.
