Influence of multi factors on external short circuit of lithium-ion battery

This paper investigates the mechanisms and influencing factors of external short circuit (ESC). The findings reveal that the evolution of characteristic parameters is closely associated with charge transfer reactions, Li⁺ transport in the electrolyte, and Li⁺ diffusion within the solid active materials. Charge transfer reaction is the limiting factor at the start of ESC. Subsequently, the high concentration gradient in solids and local lithium accumulation and depletion at anode and cathode induce resistance increase in battery. Temperature increases with time, the resistance decreases, resulting in an augmented discharging current. The discharging current changes less afterwards, as Li⁺ transport in the electrolyte and diffusion in the solid are in equivalent with charge transfer reaction. When the temperature exceeds a certain threshold, separator shrinkage induces micro internal short circuits, consequently decreasing the discharging current and inducing continuous temperature increase. External pressure reduces porosity, making Li⁺ transport in the electrolyte more challenging, which becomes the limiting factor for rapid discharging. Safety of battery increases with the increase of external pressure. While battery resistance decreases with rising ambient temperature, safety of battery increases within the temperature range of 14–30 ℃. Aged batteries exhibit increased resistance and reduced thermal stability, leading to decreased safety performance.