Constructing a stable interface on Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode via lactic acid-assisted engineering strategy

Abstract

Ni-rich layered oxides are potential cathode materials for next-generation high energy density Li-ion batteries due to their high capacity and low cost. However, the inherently unstable surface properties, including high levels of residual Li compounds, dissolution of transition metal cations, and parasitic side reactions, have not been effectively addressed, leading to significant degradation in their electrochemical performance. In this study, we propose a simple and effective lactic acid-assisted interface engineering strategy to regulate the surface chemistry and properties of Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode. This novel surface treatment method successfully eliminates surface residual Li compounds, inhibits structural collapse, and mitigates cathode-electrolyte interface film growth. As a result, the lactic acid-treated LiNi0.8Co0.1Mn0.1O2 achieved a remarkable capacity retention of 91.7% after 100 cycles at 0.5 C (25 °C) and outstanding rate capability of 149.5 mA h g−1 at 10 C, significantly outperforming the pristine material. Furthermore, a pouch-type full cell incorporating the modified LiNi0.8Co0.1Mn0.1O2 cathode demonstrates impressive long-term cycle life, retaining 81.5% of its capacity after 500 cycles at 1 C. More importantly, the thermal stability of the modified cathode is also dramatically improved. This study offers a valuable surface modification strategy for enhancing the overall performance of Ni-rich cathode materials.