Unveiling the Enhanced Electrochemical Performance of LiNi_0.5Mn_0.3Co_0.2O₂?sol-gel coated with Li-La-Zr-O based gel

The LiNi0.5Mn0.3Co0.2O2 (NMC532) cathode surface has been coated with LLZO using the citric acid-aided sol-gel technique by adjusting the coating ratio and the annealing temperature. As a result, a thin coating layer is obtained on the cathode surface. LaMO3 formation is observed due to the diffusion of lanthanum ions during the high-temperature annealing process. Electrochemical examinations demonstrated that the electrochemical behaviour of coated samples improved compared to the uncoated sample. In particular, samples coated with 2 % LLZO with annealing temperatures higher than 700 degrees C deliver a desirable capacity retention of 92 % at 0.1 C after 100 cycles and an improved discharge capacity of 102 mA h g(-1) at 1 C. Furthermore, electrochemical impedance spectroscopy measurement reveals that 2 % LLZO-coated samples with annealing above 700 degrees C have lower interface resistance than pristine NMC532. These findings provide a practical understanding of the NMC/LLZO coating interface in terms of phase formation and chemical composition and its effect on the electrochemical performance. (c) 2023 Elsevier B.V. All rights reserved.