Pre-Disordering for Preserving Transition Metal-Oxygen Covalency in Lithium-Rich Layered Oxide Cathodes

Abstract

Anionic redox in lithium-rich layered oxides (LRLOs) offers a breakthrough to higher energy density but is limited by voltage hysteresis arising from irreversible structural disorder. While enhancing transition metal-oxygen (TM-O) covalency through pi-type interaction improves the reversibility of anionic processes, inevitable structural disorder during the first cycle still deteriorates TM-O hybridization. Here, we propose a counterintuitive strategy that embraces pre-synthetic cation disorder to preserve TM-O pi-redox. The in-plane disordered arrangement modulates the first-cycle phase evolution, suppressing O3-O1 slab gliding and relaxing localized cationic oxidation at high voltage. This structural control maintains robust TM-O coordination and stabilized oxygen states even under high-voltage operation, yielding markedly reduced voltage hysteresis (0.31 vs 0.62 V) and exceptional long-term stability with minimal voltage decay (-0.04 mV cycle-1) and 98.0% energy retention after 160 cycles. This work establishes structural-disorder-driven phase evolution control as a practical design principle for stabilizing pi-redox chemistry, achieving high-energy, structurally resilient LRLOs.