Enhancing the Electrochemical Performance of LiNiCoMnO by VO/LiVO Coating.

Despite layered LiNiCoMnO having drawn much attention for their high capacity and high energy density, they still endure strong capacity decay upon prolonged cycling and high C-rates, primarily due to sluggish Li and charge-transfer kinetics and detrimental parasitic reactions with the electrolyte. To address these issues, application of a surface-coating layer made of VO/LiVO on LiNiCoMnO (V-NCM) is pursued. Benefiting from the ionic conductivity of LiVO and the electronic conductivity of VO, resulting in both enhanced Li diffusion and charge-transfer kinetics, the coated material offers significantly improved C-rate capability. Additionally, better long-term cycling performance is achieved mostly due to the mitigated parasitic reactions at the electrode/electrolyte interface that result in lower structural degradation. As a result, Li/V-NCM cells deliver over 100 mA h g capacity at 10 C and also achieve 86.1% (2 C) and 94.1% (10 C) capacity retention after 200 cycles. These V-NCM cells operate quite stably even at elevated temperature, that is, 40 and 60 °C. The coating strategy herein reported may also be useful to enhance the cycling stability and C-rate capability of other layered cathode materials.