Degradation of commercial Li₄Ti₅O₁₂-based lithium-ion batteries under extremely fast cycling rates

Li₄Ti₅O₁₂ (LTO) is a promising anode material for lithium-ion batteries (LIBs) due to its good cycle stability, rate capability, and safety. The relatively high Li⁺ intercalation plateau of about 1.55 V prevents the occurrence of lithium plating even at extremely high C-rates. In this study, we introduce a test protocol that can accurately evaluate the high-rate cycling performance of LTO-based LIBs. Two types of large-format commercial batteries are investigated, one with a capacity of 13 Ah (battery-A) and one with 3 Ah (battery-B). By incorporating two low-C-rate cycles every 50 high-C-rate cycles, we identify not only the overall capacity degradation but also the shifting state-of-charge range that the two types of batteries go through during cycling tests at various high C-rates (from 5C to 20C). Based on the uncovered mechanisms, a single-particle model is developed that can predict the aging behavior of the tested batteries at different C-rates. The study provides a simple onboard testing protocol to accurately evaluate the performance of LTO-based batteries.