Directional Polarization of a Ferroelectric Intermediate Layer Inspires a Built‐In Field in Si Anodes to Regulate Li+ Transport Behaviors in Particles and Electrolyte

Abstract The silicon (Si) anode is prone to forming a high electric field gradient and concentration gradient on the electrode surface under high‐rate conditions, which may destroy the surface structure and decrease cycling stability. In this study, a ferroelectric (BaTiO3) interlayer and field polarization treatment are introduced to set up a built‐in field, which optimizes the transport mechanisms of Li+ in solid and liquid phases and thus enhances the rate performance and cycling stability of Si anodes. Also, a fast discharging and slow charging phenomenon is observed in a half‐cell with a high reversible capacity of 1500.8 mAh g−1 when controlling the polarization direction of the interlayer, which means a fast charging and slow discharging property in a full battery and thus is valuable for potential applications in commercial batteries. Simulation results demonstrated that the built‐in field plays a key role in regulating the Li+ concentration distribution in the electrolyte and the Li+ diffusion behavior inside particles, leading to more uniform Li+ diffusion from local high‐concentration sites to surrounding regions. The assembled lithium‐ion battery with a BaTiO3 interlayer exhibited superior electrochemical performance and long‐term cycling life (915.6 mAh g−1 after 300 cycles at a high current density of 4.2 A g−1). The significance of this research lies in exploring a new approach to improve the performance of lithium‐ion batteries and providing new ideas and pathways for addressing the challenges faced by Si‐based anodes.