Boron‐Doped Electrolytes as Interfacial Modifiers for High‐Rate Stable Lithium Metal Batteries

Abstract In this article BF3 etching is applied to fabricate basic SEI (B‐SEI) layers enriched with LiF and Li x BF y . Artificial solid electrolyte interface (A‐SEI) with a “stromatolite” structure is formed on top of the B‐SEI growth during the charge‐discharge cycles. The structure of A‐SEI is characterized laterally and longitudinally by distribution of TEM elements and depth‐profile XPS, providing evidence for the elucidation of a new lattice‐tuning Li+ “layered” deposition‐type SEI structure. At the same time, the SEI is kept from electrolyte erosion fracturing during deposition, resulting in the growth of dendrites along the fracture and significantly enhanced cycling stability under high‐rate cycling conditions. In particular, A‐SEI endows significantly enhanced cycling capability to the full battery at high cycling rate and high current density. The full cell of A‐SEI @ Li||LiPF 6 ||LFP exhibits an extended lifetime after 2000 cycles at current densities up to 10 C, and still process a CE above 99.0%.