Lithiated PAA‐Coated SiO _x Anode for Stable and High‐Capacity Lithium‐Ion Batteries: Interfacial Regulation and Volume Expansion Suppression

Silicon suboxide (SiO_x) is a promising anode material for high-energy-density lithium-ion batteries, but its large volume change and low intrinsic conductivity hinder practical application. These issues cause parasitic side reactions with the electrolyte, leading to continuous electrolyte consumption and slow ion/electron transport, thereby limiting achievable capacity and energy density. To address these challenges, this study developed a strategy using lithiated polyacrylic acid (LiPAA) to modify micron SiO_x via spray drying, constructing spherical SiO_x@LiPAA composites. The LiPAA polymer infiltrates the surface of SiO_x, forming a solid spherical structure. It establishes an effective conductive network to enhance electron transport, promotes lithium-ion desolvation for improved kinetics, and acts as an elastic buffer to maintain structural integrity under high area load. Simultaneously, the polymer promotes a denser, thinner, and LiF-rich solid electrolyte interface (SEI), inhibiting parasitic reactions and ensuring stable cycling. Electrochemical tests showed the composite retains a reversible specific capacity of 1234.06 mAh g^-1 after 200 cycles at 0.5C. At a high rate of 4.0C, the reversible capacity was 536.2 mAh g^-1. When paired with a LiFePO₄ cathode, the full cell maintained 86.4% capacity retention after 500 cycles. This work offers a feasible route to develop high-performance, low-cost, and scalable silicon-based anodes.