Fluorinated carbon nitrides assisted solvation-regulation engineering toward polyvinylidene fluoride-based electrolytes for long-lifespan solid-state lithium batteries

Abstract

Polyvinylidene fluoride (PVDF)-based electrolytes show huge potential in applications of solid-state lithium batteries (SSLBs) due to their broad potential windows and reliable mechanical strengths. However, the critical interfacial issues associated with high-reactivity residual solvents enable rapidly deteriorative stability of electrolytes toward long-term cycling. Herein, a solvation-regulation engineering is proposed by introducing two-dimensional fluorinated C3N5 (F-C3N5) with distinct electronic structure for restraining residual solvents. The strong adsorption effect of F-C3N5 contributes to selective capture of residual solvent, thereby enabling more anions being participated in solvation by weakening binding strength between Li+ and solvent. Both anion-rich solvation structures and F-C3N5 fillers are involved in forming inorganic-dominated cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) layers, which inhibit undesirable parasitic reactions occurred at electrode/electrolyte interfaces. Consequently, the integration of F-C3N5 with PVDF-based electrolyte endows Li symmetric cell with a high critical current density of 2.3 mA cm−2, and a stable Li plating/stripping cycling of 800 h at 0.5 mA cm−2. The corresponding LiNi0.6Co0.2Mn0.2O2/Li cell delivers an excellent capacity retention of 86.4% after 300 cycles at 1C. This work provides a novel perspective of using functionalized F-C3N5 to tailor solvation structures for stabilization of PVDF-based electrolytes.