Achievement of Superhigh Discharge Capacity in Lithium Rich Oxide Cathode Materials via Modification of Localized Structure

Owing to anionic redox, cathode materials containing layered Li-rich Mn-based oxides (LLOs) are promising for the development of next-generation lithium-ion batteries (LIBs) with a large energy density (~500–600 Wh·kg⁻¹). However, these LLOs are easily degraded during cycling, which limits their lifespan. So far, the degradation mechanism is still under debate. Herein, LLOs are post-treated through implantation with energetic Ti ion flux (Ti-LLO), which modifies the structure of LLOs both at the surface and within the bulk. Unlike the dominant R3̅m phase (73.24%) observed in LLOs, the phase structure of Ti-LLO is altered, with Li-rich C2/m accounting for 67.72% in the bulk, alongside the formation of a thin (approximately 2 nm), uniform, and continuous Li-Ti-O spinel layer at the surface. Apart from phase structure changes, chemical valence states of transition metals and O, as well as their evolution, are analyzed and compared to charge transport kinetics to elucidate their contributions to the enhanced discharge capacity in Ti-LLOs. Besides, the role of the Li-Ti-O spinel layer at the surface in providing anticorrosion protection at the interface of LLOs/electrolyte during cycling is evaluated. As a result, we demonstrate that a superhigh discharge capacity (335.3 mAh·g⁻¹) at 0.1 C can be achieved, along with prolonged cycling stability (showing capacity retention of approximately 80% after 500 cycles at 1 C) through these modifications. Moreover, we confirmed the universality of the strategy by implanting other ions, which offers practical strategies for achieving high performance in LLO cathode materials through thermodynamics and kinetics pathways. © 2025 The Authors. Carbon Energy published by Wenzhou University and John Wiley & Sons Australia, Ltd.