Control of Li-ion transport through a combination of conductive coating and charging protocol for a stable and extremely fast charging cathode

Abstract

This study demonstrates the importance of controlling Li-ion transport through a combination of conductive coating and charging protocol to achieve a stable and extremely fast charging cathode. In this research, the LiFePO4 (LFP) material coated with carbon (C) and Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte exhibits superior performance to the conventional carbon-coated LFP (LFP@C), especially at high current rates, demonstrating the possibility of developing an extremely fast charging cathode for practical applications. Our systematic experimental results reveal that the LATP coating effectively regulates the surface reactions, prolongs the voltage plateaus, and contributes additional capacity to the olivine LFP cathode material. To take advantage of the coating, a charging protocol consisting of multi-step constant current (MCC) charging combined with constant voltage (CV) charging has been proposed. During MCC charging, the current gradually increases to initiate Li-ion transport on the particle surface before accelerating charging in a short time. Under the proposed charging protocol, the LFP@C_LATP can stably deliver an average charge capacity of 161.7 mAh g−1 within 10 min for 100 cycles. This research also demonstrates the advantage of incorporating a Li-ion conductor into the electrode for the development of an extremely fast charging electrode.