Li ₂ SeO ₄ Coating Combined with Electronic Structure Tuning To Stabilize the Mo-Doped Cobalt-Free High-Nickel Cathode Material

Cobalt-free high-nickel layered cathode materials exhibit great potential for achieving higher energy density, but their cycling stability is largely compromised by inherent interfacial and mechanical instabilities. Molybdenum (Mo) doping could refine the size of primary particle, thus alleviating stress accumulation. Nevertheless, particle refinement leads to an increased specific surface area, making interfacial instability still a critical limitation for cycling stability. Therefore, we constructed a Li 2 SeO 4 modification on the surface of LiNi 0.95 Al 0.04 Mo 0.01 O 2 (NiAlMo) via high-temperature reaction between low-melting SeO 2 and residual lithium, which suppresses the overgrowth of surface byproducts and mitigates the structural degradation through electronic modulation of surface lattice oxygen. The LiNi 0.95 Al 0.04 Mo 0.01 O 2 -Li 2 SeO 4 (NiAlMo-Se) delivers 248.2 mAh/g at 0.1 C and 224.2 mAh/g at 0.5 C, with 85.2% capacity retention after 100 cycles within 2.7–4.5 V. And the rate capability of NiAlMo-Se is also significantly enhanced, reaching 178.6 mAh/g at 5 C and 154.4 mAh/g at 10 C. Simultaneous enhancement of mechanical strength and surface stability through microstructure modulation and surface modification represents a viable strategy to stabilize polycrystalline high-nickel layered cathodes.