A novel quantitative electrochemical aging model considering side reactions for lithium-ion batteries

A novel quantitative electrochemical aging model for lithium-ion batteries considering side reactions is proposed in this paper. The resistance of solid electrolyte interphase and the thickness of deposited layer caused by side reactions are utilized as degradation representatives to explicitly quantify the aging effects. The aging model is established through deriving the transfer function relationship between the aging representatives and input current history. Therefore, the gap between macroscopic (battery operating mode) and microscopic (aging mechanism) can be well bridged. The aging mechanisms for the lithium-ion batteries are well identified by comprehensive post-mortem analysis. The experimental results demonstrate that the irreversible side reactions occurring at the surface of anode particles are the primary cause for performance degradation in this study. To verify the proposed aging model, the comparisons are made between experimental and simulated results at both macroscopic cell-level (cell voltage response, capacity fade, and solid-electrolyte interphase resistance increase) and microscopic-level (deposited-layer growth). The capacity decay error is bounded to 3% up to 400 cycles. The results demonstrate that the presented transfer-function type aging model is capable of predicting battery degradation severity precisely.