Enhanced stability and dendrite suppression in lithium metal batteries via PVDF–HFP-based composite protective layers

The advancement of lithium metal batteries (LMBs) is crucial for next-generation high-energy storage systems, particularly for electric vehicles. However, their practical implementation is hindered by uncontrolled lithium dendrite growth, leading to capacity degradation and poor cycling stability. This study introduces a composite protective layer (CPL) composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and SiO₂ particles to address these challenges. The CPL effectively suppresses dendrite formation and stabilizes the solid-electrolyte interphase, enhancing cycling stability and electrochemical performance. The optimized CPL exhibits excellent electrochemical stability within a 4.7 V potential window and a high lithium-ion transference number of 0.37. Symmetric CPL-coated lithium cells demonstrate stable plating-stripping behavior over 400 cycles at a current density of 2 mA cm⁻² with a fixed areal capacity of 2 mAh cm⁻². In a full-cell configuration with an NCM622 cathode, the CPL-coated lithium anode retains a reversible areal capacity of 3.08 mAh cm⁻² over 450 cycles, achieving 90.9 % capacity retention and an average coulombic efficiency of 99.77 % at a 0.5C/1.0C charge-discharge rate. This organic-inorganic hybrid strategy provides a promising approach to mitigating key challenges of lithium metal anodes, extending battery lifespan, and enhancing safety for high-energy storage applications.