In situ interfacial reconstruction coupled with phosphorus gradient doping for achieving durable and high energy Li-rich cathodes

Li-rich cathode materials (LRMs) achieve high capacity through anionic redox reactions above 4.5 V, but their performance is severely constrained by poor structural stability and irreversible oxygen loss. Herein, this work proposed a low-temperature gas-solid interfacial engineering to reconstruct the surface and bulk phases in situ , forming a multifunctional surface layer composed of a dual Li 3 PO 4 /spinel structure, abundant oxygen vacancies, and bulk P gradient doping. Experiments and calculations revealed that surface oxygen vacancies promoted transition metal (TM) migration and spinel phase formation, thereby enhancing Li + diffusion and mitigating lattice strain. The Li 3 PO 4 coating protected against electrolyte corrosion and stabilized the interface, meanwhile, bulk P doping formed strong P–O bonds that stabilized the oxygen framework, suppressed oxygen release, and improved the reversibility of anionic redox reactions. As a result, the modified LRMs exhibited significantly improved cycling performance, retaining 81.16% of the initial capacity after 200 cycles at 2C. This study provides a promising strategy for developing high energy density and long cycle life cathode materials for next-generation lithium-ion batteries. • An innovative gas-solid interfacial reaction enables in situ surface-to-bulk reconstruction of Li-rich cathode materials. • PH 3 atmosphere induces oxygen vacancies, stabilizing lattice oxygen and suppressing high voltage irreversible oxygen release. • Li 3 PO 4 coating and highly compatible spinel phase enhance structural stability and Li + diffusion kinetics. • Phosphorus gradient doping synergistically optimizes structural and interfacial stability.