<p>Silicon (Si) anodes promise attractive application prospects owing to their high theoretical specific capacity and appropriate lithiation potential. However, severe volume expansion and unstable solid electrolyte interphase (SEI) formation hinder their practical commercialization. Herein, an interface engineering strategy by coating Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) is proposed to optimize electrochemical/mechanical properties of SEI on the Si electrode. Porous micro-spherical structure of Si@LLZTO particles promotes compactness of the electrode and alleviates volume expansion during cycling. Coating LLZTO induces Li₄SiO₄ formation owing to the reaction of SiO₂ on the Si surface and Li₂CO₃ on LLZTO. The H⁺/Li⁺ exchange of LLZTO and decomposition of LiPF₆ are facilitated due to the presence of trace water in the electrolyte, resulting in LiF formation. The interfacial layer rich in LLZTO, LiF and Li₄SiO₄ manipulates ion transport and volume variation of Si electrodes, inhibiting SEI rupture and regeneration. The Si@LLZTO∥Li cells deliver reversible capacity of 1961 mAh g⁻¹ with 89.1% capacity retention after 100 cycles at 1 C. The Si@LLZTO∥NCM 811 cells possess 78.6% capacity retention after 200 cycles at 0.5 C, superior to that of Si∥NCM811 cells (31.5%). The LLZTO-coating strategy with in-depth comprehension on interfacial mechanisms enlightens electrode design for high-performance Si-based lithium-ion batteries.</p>