Li₂ZnSiO₄ coherent coating on high-voltage LiNi_0.5Mn_1.5O₄ cathode for promoting cycling stability and rate capability

High-voltage cobalt-free spinel cathode material LiNi_0.5Mn_1.5O₄ (LNMO) is promising for high-energy–density lithium-ion batteries (LIBs). Due to severe electrode–electrolyte interfacial side reactions and crystal structure destruction, unexpected rapid capacity degradation limits its practical applications. To substantially enhance the structure and interface stability, here a coherent Li₂ZnSiO₄ (LZSO) coating is applied for protecting LNMO against HF corrosion and electrolyte decomposition. The as-formed coherent-interface LZSO coating is responsible for inducing the transformation of Jahn-Teller distortion from an elongated to a compressed state. In addition to the fast Li⁺ transport capability of LZSO, the gradient Si-doping in the LZSO coating also promotes the Mn³⁺ concentration in the near surface region of LNMO, which simultaneously enhances both electronic and ionic conductivity. As a result, the corresponding cycling stability of LZSO-coated LNMO is substantially improved (capacity retention 95.47 % after 200 cycles at 0.5C, 25 °C, and even at 55 °C, 92.33 % after 100 cycles). Furthermore, at the high rate of 5C, LZSO-coated LNMO exhibits considerable specific capacity and capacity retention (∼100mAh g⁻¹, 86.87 % after 100 cycles). The surface modification strategy here has paved new way for boosting development and practical utilization of LNMO in high-energy–density LIBs.