Three-Dimensional Nanoporous Polyethylene-Reinforced PVDF-HFP Separator Enabled by Dual-Solvent Hierarchical Gas Liberation for Ultrahigh-Rate Lithium Ion Batteries

High-power lithium ion batteries (LIBs) have extensive applications ranging from electronic devices to electric vehicles. The composition and structure of separators largely impact the rate performances of LIBs. Here, a three-dimensional (3D) nanoporous poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP)- polyethylene (PE) composite separator is obtained through solvent liberation. The composite separator owns a high ionic conductivity of 1.01 mS.cm lithium ion batteries (LIBs) have extensive applications ranging from electronic devices to electric vehicles. The composition and structure of separators largely impact the rate performances of LIBs. Here, a three-dimensional (3D) nanoporous poly((-1) at room temperature due to the high porosity up to 95.6% and the uniform 3D pore distribution. LiFePO4/Li half-cells with the composite separator deliver record rate capacities of 97 mAh.g(-1) at 10 C and 57 mAh.g(-1) at 20 C. PE in the composite separator significantly enhances the mechanical strength and thermal stability of the separator. Theoretical calculations show that the difference in the absorption energy between acetone and NMP solvent on PVDF-HFP is the major driving force for the formation of the inter-island structure, which provides massive Li+ transport channels during high-rate battery cycling.