“Faraday Cage” Induced Anion-Confined Interface Enables Industrially Compatible Microsized Silicon Anodes

Abstract

The anion-derived inorganic-rich solid electrolyte interphase (SEI) provides highly desirable protection for anodes; however, it is hardly formed in commercial electrolytes due to the electromigration of free anions away from anodes under the charging electric field. High-concentration electrolytes are capable of curing this issue, but they are economically impractical. Here, we pioneer an industrially compatible approach to shield the electric field by engineering a surface "Faraday cage" from a polymer matrix electrostatically integrated with a weakly dissociated salt. An anion-confined interphase (ACI) is produced on the representative silicon microparticles (SiMPs). The ACI enables a sustainable anionenriched microenvironment, which promotes the participation of anions in the Li + solvation sheath and guarantees more anion reduction to the inorganic-rich SEI upon long cycling stability at a high areal capacity (∼4 mAh cm −2 ). This approach offers a straightforward yet practical solution to SEI innovation in commercial batteries.