Synergistically modified lithium-rich manganese-based cathodes via Zn doping and Al2O3 coating for enhanced lithium-ion batteries

Abstract

Lithium-rich manganese-based cathodes are promising for high-energy-density lithium-ion batteries but are hindered by poor cycling stability and rate capability. This study demonstrates that synergistic Zn²⁺ doping and Al₂O₃ coating effectively enhance their electrochemical performance. Structural analyses reveal that moderate Zn doping (LNCM@Zn2) expands the (003) interplanar spacing from 0.47 nm to 0.496 nm, lowers Li⁺ diffusion barriers, and suppresses transition-metal cation mixing. These modifications yield an initial discharge capacity of 276.4 mAh g⁻¹ at 0.1C with improved rate performance. However, excessive doping (LNCM@Zn3) induces lattice overexpansion, causing structural instability and capacity fade. Concurrently, the Al₂O₃ coating acts as a protective layer, mitigating structural degradation and enhancing interfacial conductivity. The dual-modified Zn-doped and Al₂O₃-coated LNCM exhibits significantly enhanced cycling stability and superior high-rate capability compared to pristine materials. Optimal performance is achieved with the co-modified LNCM@Zn2@Al₂O₃, which maintains high discharge capacity at high current densities due to the combined benefits of the stabilized bulk structure (Zn doping) and protected surface (Al₂O₃). These results establish Zn doping coupled with Al₂O₃ coating as a viable strategy for developing high-performance LNCM for next-generation batteries.