Boosting Li⁺ Diffusion in Lithium-Rich Oxides through Intrinsic Structural Design: Insights and Design Principles

Lithium-rich oxide cathodes present high specific capacities (> 250 mAh g^-1) and wide operating voltage windows (2.0-4.8 V), making them promising candidates for next-generation high-energy batteries. Their practical deployment, however, is limited by sluggish ion transport kinetics that arise from inherent structural constraints, including confined two-dimensional diffusion channels, transition metal migration, and local lattice distortions. These structural perturbations narrow Li⁺ pathways, intensify cation mixing, and generate localized strain fields, collectively increasing the Li⁺ migration energy barrier. To facilitate the rational design of fast-kinetic lithium-rich oxides through intrinsic structural optimization, a comprehensive elucidation of the structure-diffusion interplay is presented, with emphasis on the roles of lattice distortion and oxygen redox chemistry in modulating Li⁺ pathways and associated energy barriers. Structural design strategies that aim to improve ionic diffusivity are systematically evaluated, including interface engineering, morphology-directed design, and the modulation of redox chemistry. Advanced operando characterization techniques that capture dynamic structural and chemical evolution are also described as essential tools for guiding precise structure-performance analysis. The mechanistic insights and integrated analytical approaches summarized in this review establish a robust conceptual foundation for engineering lithium-rich oxides with enhanced ion transport kinetics, thereby supporting the advancement of next-generation high-power battery technologies.