Dual Enhancement of Ionic Conductivity and Dendrite Suppression in PVdF–HFP Solid Electrolytes via Hexagonal Boron Nitride Integration

Solid-state batteries (SSBs) with lithium metal anodes offer exceptional energy density but suffer from dendrite growth and limited interfacial stability. Here, we report a poly(vinylidene fluoride-co-hexafluoropropylene)-based solid electrolyte incorporating hexagonal boron nitride (h-BN) as a multifunctional filler and lithium bis(trifluoromethanesulfonyl)imide as a salt to simultaneously enhance ionic conductivity and suppress dendrite formation. The optimized composition (3 wt % h-BN, PB3) achieves an ionic conductivity of 6.44 × 10–4 S cm–1 and a reduced electronic conductivity of 6.85 × 10–9 S cm–1. This balance enables stable lithium plating/stripping for over 200 h in symmetric cells and a capacity retention of ∼93% over 150 cycles in Li||LiNi0.6Co0.2Mn0.2O2 cells. Mechanistically, the insulating nature of h-BN and anion-trapping capability promote uniform Li-ion flux, mitigating localized dendrite nucleation. This dual functionality of h-BN offers a promising design pathway for safe, high-performance all-solid-state batteries.