Construction and performance of PVDF-HFP-matrix comb-like gel copolymer electrolyte for high-performance quasi-solid-state lithium-metal batteries

Abstract

Rechargeable lithium metal batteries (LMBs) have encountered bottlenecks in energy density, durability, and safety issues. Designing functional polymer electrolytes has been considered as an effective way to develop high-performance of LMBs. In this study, PVDF-HFP-matrix polymeric electrolytes blended with copolymer P(MMA-co-PEGMEMA) (PPxPy) via a simple one-pot free-radical polymerization are successfully designed and prepared. It has been found that the PPxPy electrolytes can construct different comb-like networks via systematically tuning monomer ratios. The tailored PP5P5 gel electrolyte exhibited high ionic conductivity of 0.74 × 10−3 S cm−1 at room temperature (RT), an enlarged electrochemical window up to 4.77 V, high lithium-ion transference number tLi+ of 0.65, and good mechanical property with Yang's modulus up to 131 MPa. Benefited from these good properties, the Li||LiFePO4 batteries assembled with PP5P5 gel electrolyte achieved an exceptional discharge capacity of 152 mAh g−1 with nearly 100 % Coulombic efficiency after 150 cycles at 1C. Furthermore, the Li|PP5P5|NCM811 cell exhibits excellent reversible specific capacity of 188 mAh g−1 at 0.1C. Consequently, it can be anticipated the as-prepared functional polymer structure to provide a reliable method for the preparation of polymer electrolytes in quasi-solid-state batteries with high-energy-density.