Li4SiO4 coating enables stable interfaces and voltage suppression in Ni-rich cathodes for Li-ion batteries

Constructing a robust, highly Li-ion-conductive surface layer is an effective strategy to improve the interfacial stability of nickel-rich cathodes like LiNi 0 . 8 Co 0 . 1 Mn 0 . 1 O 2 (NCM811). However, existing methods often fail to balance ion/electron conductivity with suppression of surface phase transformations, leading to poor rate capability, cycling stability, and energy density. This work introduces an in-situ solution-phase formed coating of Li 4 SiO 4 (LSO) that creates a continuous ion/electron-conductive network across NCM811 particles. This LSO enhances lithium-ion transport, builds a stable electrode/electrolyte interface, and alleviates mechanical stress during cycling. As a result, NCM811@LSO exhibits improved electrochemical performance, including reduced voltage decay and stable operation at high voltages. The LSO coating suppresses surface degradation, intergranular cracking, and parasitic reactions by shielding active sites and reducing direct electrolyte contact. It also mitigates electrode polarization and localized overcharging during long-term cycling. Full-cell tests using graphite and SiO/C anodes confirm high energy densities, reaching 765 Wh kg −1 in NCM811@LSO//graphite cells. Furthermore, density functional theory (DFT) calculations support the experimental findings, revealing that LSO promotes favorable interfacial chemistry, suppresses internal cracking, inhibits nickel migration, and prevents irreversible phase transformations. Compared to traditional coatings, the multifunctional LSO layer offers superior protection and conductivity, making it a promising approach for developing advanced, high-energy-density lithium-ion batteries.