Robust LiNi 0.6 Mn 0.4 O ₂ Cathode Achieved from the Dual-Function Strategy of Microstructural Stress Dissipation and Crystalline Phase Ion Transport Improvement

LiNi0.6Mn0.4O₂ (NM64), a cobalt-free cathode material with high theoretical capacity and approximately 30% lower cost than commercial LiNi0.6Co0.2Mn0.2O₂ (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.