Kinetically induced memory effect in Li-ion batteries

Abstract

Effective optimization and control of lithium-ion batteries cannot neglect the relationship between fundamental physicochemical phenomena and performance. In this work, we apply a multi-step charging protocol to commercially relevant electrodes, such as LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811), LiFePO₄ (LFP), LiMn_1.5Ni_0.5O₄ (LMNO), LiMn_0.4Fe_0.6PO₄ (LMFP), Li₄Ti₅O₁₂ (LTO) and Na₃V₂(PO₄)₃ (NVP), to investigate how the initial rate affects their kinetic response. Remarkably, electrodes undergoing phase separation exhibit a pronounced counter-intuitive memory effect under high-rate operating conditions. Using operando microbeam X-ray diffraction, the origin is demonstrated to be embedded in rate-dependent multi-electrode particle dynamics. Developed phase-field electrochemical models capture the collective behaviour of electrode particles underlying the kinetically induced memory effect, establishing how the thermodynamics of the nanoscale (primary particle) level affects the macroscopic electrode response under realistic conditions. Building upon these findings, an analytical model is presented, capable of capturing and predicting these effects. These results challenge established battery management strategies, opening the doors for improved characterization and optimization of fast-charging protocols, crucial in minimizing aging and heat production while enhancing energy efficiency and benefitting a wide range of battery-powered applications.