Simplified electrochemical model assisted detection of the early-stage internal short circuit through battery aging

Abstract

The internal short circuit (ISC) is one of the main reasons triggering battery thermal runaway. This study proposes and demonstrates that the apparent diffusion coefficient can be employed as a highly sensitive indicator to alarm ISC during battery aging. The intrinsic parameters are identified with terminal voltage input under the simplified pseudo-two-dimensions model to examine their sensitivities to the ISC. In the experiment, the battery cells with different remaining capacities are subjected to three drive cycles and four ISC degrees from 100 Ω to 10 Ω. The identification results for the three loads are similar, but a small, highly dynamic power load is more desirable due to its lower error within 50 mV. Moreover, the identified diffusion coefficients are considerably responsive for all levels of ISC resistance once triggered, exhibiting as high as 85 % variation for 10 Ω ISC resistance. More importantly, the sensitivity of the diffusion coefficients for 100 Ω ISC detection significantly increases from 8 % to 55 % as the battery degrades. Finally, the effectiveness of the apparent diffusion coefficient method is compared with other commonly applied indicators, such as terminal voltage, internal resistance, and incremental capacity analysis.