Robust LiNi0.6Mn0.4O2 Cathode Achieved from the Dual-Function Strategy of Microstructural Stress Dissipation and Crystalline Phase Ion Transport Improvement

Abstract

LiNi_0.6Mn_0.4O₂ (NM64), a cobalt-free cathode material with high theoretical capacity and approximately 30% lower cost than commercial LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622), is a promising cathode for lithium-ion batteries. However, structural instability and sluggish kinetics limit its potential for large-scale commercial applications. To address these challenges, we propose a dual-function strategy that simultaneously enhances ion transport by reducing cation mixing and dissipates stress via elongated primary grains in oxygen-calcined NM64 (O-NM64), achieving superior robustness. Consequently, the O-NM64 exhibits a high specific capacity of 201.6 mAh g^-1 at 0.2 C, coupled with a high-rate capability of 153.40 mAh g^-1 at 10 C and long-term cycling stability, as evidenced by an 81.38% capacity retention after 450 cycles at 0.2 C (more than 220 days of continuous operation). Moreover, a 20 kg-scale pouch cell shows no significant capacity degradation over 300 cycles. This work demonstrates an effective approach for developing high-energy, high-power, long-cycle, resource-saving, and low-cost cathodes, offering insights into sustainable battery technologies that balance performance and cost.

Keywords: calcination atmosphere; cobalt-free layered oxide cathode; crystalline phase engineering; lithium-ion batteries; microstructure engineering.