Fluorinated Solvent‐Coupled Anion‐Derived Interphase to Stabilize Silicon Microparticle Anodes for High‐Energy‐Density Batteries

Si microparticle (SiMP) anodes feature much lower production cost and higher tap density compared to their nanosized counterparts, which hold great promise for high‐energy‐density lithium‐ion batteries, yet they suffer from unavoidable particle pulverization during repeated cycling, thus making their practical application extremely challenging. Herein, a non‐flammable localized high‐concentration electrolyte (LHCE) is rationally formulated using a fluorinated solvent, 2,2,2‐trifluoroethyl methyl carbonate (FEMC), to induce fluorinated solvent‐coupled anion‐derived interfacial chemistry. Unlike other LHCEs, the FEMC‐based LHCE is demonstrated to build a highly robust and stable F‐rich inorganic–organic bilayer solid–electrolyte interphase on SiMP anode, which endows stable cycling of SiMP anode (≈3.4 mAh cm−2) with an ultrahigh Coulombic efficiency of ≈99.7%. Coupled with its high anodic stability, the FEMC‐based LHCE endows unprecedented cycling stability for high‐energy‐density batteries containing high‐capacity SiMP anodes with Ni‐rich LiNi8Mn1Co1O2 or 5 V‐class LiNi0.5Mn1.5O4 cathodes. Remarkably, a 1.0 Ah‐level SiMP||LiNi8Mn1Co1O2 pouch‐cell stably operates for more than 200 cycles, representing the pioneering report in pouch cells containing SiMP anodes. A fluorinated solvent is incorporated into localized high‐concentration electrolyte to induce fluorinated solvent‐coupled anion‐derived interfacial chemistry, which yields a highly robust and stable F‐rich inorganic–organic bilayer solid–electrolyte interphase to enable stable cycling of Si microparticle anode. This electrolyte overcomes the longstanding challenges of Si microparticle pulverization and high‐voltage incompatibility, endowing the stable operation of high‐energy‐density Li‐ion batteries.