Dual-ion modification strategy for high-voltage mid-Ni single-crystal cathode

Abstract

Mid-Ni single-crystal Li[NixCoyMn(1-x-y)]O-2 (0.6 <= x <= 0.7) layered oxide cathodes offer superior intrinsic stabilities compared to those of conventional Ni-rich cathodes, primarily owing to their grain-boundary-free morphologies and lower Ni contents, which collectively mitigate microstructural and chemical degradation. However, increasing the cell voltage to 4.5 V to enhance the energy density significantly compromises these advantages. Furthermore, synthesizing this composition in a monolithic form requires high sintering temperatures, resulting in increased energy consumption and processing limitations. Therefore, the practical application of this cathode material requires the comprehensive resolution of these multifaceted challenges, which cannot be addressed using a single-atom doping strategy alone. In this study, we propose a dual-ion modification strategy involving the incorporation of a sintering agent and a surface stabilizing element. Each element contributes independently to the enhancement of electrochemical performance, ultimately enabling a stable, high-voltage, mid-Ni single-crystal cathode material suitable for use in advanced lithium-ion batteries.