Concurrent modification of under-surface reconstruction and additional coating layers via simple phosphoric acid treatment for high-stability Li-rich cathodes in Li-ion batteries

Abstract

The superior energy density and cost-effectiveness of Li-rich layered oxides (LLOs) make them promising candidates for next-generation cathode materials. Nevertheless, they face major obstacles that include oxygen evolution and the dissolution of transition metals (TMs) during high-voltage cycling. To address these stability issues, this study proposes a bifunctional modification strategy using H₃PO₄ that involves the formation of a spinel phase region underneath the surface and an additional Li₃PO₄ coating layer on the surface of the active material. This strategy is realized through the combination of a wet chemical reaction and subsequent heat treatment process. The resulting spinel phase with its stable oxygen lattice, and the Li₃PO₄ coating layer, contribute to the formation of a more stable electrode–electrolyte interface. Compared to the Pristine sample, the modified LLO@S@LP3 demonstrates notably enhanced rate performance and cycling durability. Moreover, the modified material shows enhanced cycling performance under harsh conditions, such as high-temperature storage and cycling, whereas electrolyte decomposition typically accelerates material degradation. The method presented enhances the performance of LLOs and reduces their degradation, while addressing critical issues that hinder their commercialization, and provides potential opportunities for their application in energy-storage materials.