Reactive selenium induced near‐surface reconstruction to stabilize high‐voltage, cobalt‐free cathodes for high‐rate, long‐cycling lithium batteries

Abstract The cobalt‐free spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) emerges as a high voltage and high energy density cathode candidate for next generation batteries, yet its practical application is challenged by intrinsic Mn dissolution, oxygen vacancy‐driven structural degradation, and unstable electrode‐electrolyte interphase. Herein, we demonstrate a reactive selenium (Se)‐induced near‐surface reconstruction strategy, which integrates SeO x coating and Se element doping into the near‐surface of LNMO through a one‐step vapor‐phase selenization process, stabilizing both the electrode‐electrolyte interphase and the bulk lattice. During electrochemical cycling, the nanoscale‐thick SeO x coating layer evolves into a Li 2 SeO x ‐rich interfacial layer, facilitating rapid Li + transport and enhancing mechanical resilience to suppress interfacial degradation caused by volume changes. Concurrently, near‐surface Se doping forms O‐transition metal (TM)‐Se bonds that narrow the bandgap between Mn 3d and O 2p orbitals, thereby stabilizing lattice oxygen, suppressing Mn dissociation and structural deterioration. The near‐surface reconstructed Se‐LNMO cathode exhibits exceptional long‐term cycling stability at high rates with a 0.018% capacity decay rate per cycle after 2000 cycles at 5C, outperforming previously reported LNMO materials. This simple yet effective “all‐in‐one” reactive Se infusion strategy serves as a universal paradigm for stabilizing high‐voltage cathodes, opening up new avenues for the design of novel high‐energy‐density cathode materials. image