Material–electrolyte interfacial interaction enabling the formation of an inorganic-rich solid electrolyte interphase for fast-charging Si-based lithium-ion batteries

Abstract

A solid–electrolyte interphase (SEI) with high stability and high Li⁺ conductivity is highly desirable for Si-based lithium-ion batteries with high energy density and superior fast charging capability. Here, we proposed constructing a superior SEI by regulating the interaction between electrolyte components and anode surfaces to achieve the above goal. With combined experimental and theoretical studies, we demonstrated that the P-based layer could selectively adsorb fluoroethylene carbonate (FEC, a common electrolyte solvent) to form a robust, thin, and dense Li₃P/LiF-dominant SEI with high ionic conductivity on SiO_x particles. SiO_x with a uniform 6 nm-thick P layer (SiO_x@P) delivered excellent electrochemical cycling stability (1050 mA h g⁻¹, 83.3% capacity retention for 1000 cycles at 1.0C). Our Ah-level LiNi_0.6Co_0.2Mn_0.2O₂||SiO_x@P pouch cell demonstrated stable cycling with a high energy density (410 W h kg⁻¹ and 780 W h L⁻¹ at 0.2C), along with an exceptional fast charging capability. It exhibited the capability to charge up to 86.5% of its capacity within 15 minutes and demonstrated 83.8% capacity retention after 250 cycles at a charging rate of 4C. This achievement offers a unique insight into SEI formation, providing new opportunities to construct an advanced SEI for Si-based anodes toward high energy density fast charging LIBs.