Morphology Engineering in Cobalt‐Free Li‐Rich Oxides for High‐Capacity and Strain‐Tolerant Cathodes

Abstract Morphology engineering plays a critical role in enhancing ionic diffusion kinetics and activating oxygen redox activity in cobalt‐free lithium‐rich layered oxides (LROs), addressing their intrinsic limitations for high‐energy‐density batteries. Herein, a morphology‐engineering strategy is proposed to synthesize cobalt‐free LRO cathodes with radially arranged primary grains (LRO‐RA) and short rod‐like grains (LRO‐SR). The radial architecture of LRO‐RA establishes fast Li ⁺ diffusion pathways, as evidenced by its near‐identical Li ⁺ diffusion coefficient to LRO‐SR despite dominating oxygen redox contributions. This accelerated ion transport facilitates reversible anionic redox, yielding a 79 mAh g ⁻¹ higher initial discharge capacity (0.1C) and a 50.6 mV lower O oxidation potential compared to LRO‐SR. Advanced spectroscopic and diffraction analyses confirm that the radial morphology stabilizes anionic redox, minimizes MnO ₆ distortion, and mitigates strain accumulation. Consequently, LRO‐RA achieves a 94.8% capacity retention after 400 cycles (1C), far exceeding LRO‐SR (75.6%), with mitigated voltage decay. Post‐cycling analysis confirms that the dense radial grains resist electrolyte infiltration and phase transformation, preserving structural integrity. This work elucidates how morphology‐driven ion transport optimization amplifies oxygen redox reversibility, offering a universal design principle for high‐capacity Li‐rich cathodes.