Quantitative lifetime prediction and operating window identification for Li4Ti5O12-based batteries under coupled thermal and rate stress

Li 4 Ti 5 O 12 (LTO)-based batteries (LTO cells) integrate the zero-strain insertion stability of LTO anodes with the high energy density of layered oxide cathodes, offering a compelling platform for high-power, long-cycle-life applications. This study presents a systematic accelerated aging investigation across a 3 × 4 stress matrix (C-rates: 5C, 10C, 15C; temperatures: 30, 40, 50, 60 °C) using the L80 end-of-life criterion (80% capacity retention), with all L80 estimates anchored to measured galvanostatic cycling data without schematic reconstruction of the capacity-retention curves. A Modified Arrhenius model was developed using 10 moderate-stress conditions: Nf = 32.40 × exp.(2196/T) × Cr -0.586 , with Ea = 18.3 kJ mol −1 (0.190 eV), β = 0.586, and MAPE = 5.8%. The practical operating regime (≤ 10C, ≤ 50 °C) achieves MAPE = 5.5%, with L80 anchored to measured cycling data via direct interpolation for five of the six practical conditions and a short linear extrapolation for the sixth (5C/30 °C). Extended evaluation at 60 °C and 15C validates the model boundary: the 15C/50 °C and 15C/60 °C conditions exhibit failure-dominated behavior, with L80 collapsing to 2016 and 120 cycles, respectively, demonstrating that conventional Arrhenius kinetics cannot capture combined extreme-stress degradation. Multi-scale post-mortem characterization (XRD/Rietveld, FE-SEM/EDS, EIS) under the representative 10C/50 °C condition identifies a hierarchical degradation sequence: cathode lattice distortion (LCO c-axis + 0.21%; NCM a-axis − 0.60%, c-axis + 0.82%) → secondary particle cracking → electrolyte-derived interphase accumulation → charge-transfer resistance rise → capacity fade. The LTO anode retains structural integrity throughout, confirming cathode-dominated system degradation. The resulting lifetime contour map defines a recommended operating window of 30–45 °C and 5–10C sustaining L80 > 8000 cycles, providing quantitative guidelines for LTO-cell reliability design.