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

Abstract 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 LiNi 8 Mn 1 Co 1 O 2 or 5 V‐class LiNi 0.5 Mn 1.5 O 4 cathodes. Remarkably, a 1.0 Ah‐level SiMP||LiNi 8 Mn 1 Co 1 O 2 pouch‐cell stably operates for more than 200 cycles, representing the pioneering report in pouch cells containing SiMP anodes.