The practical application of high-rate lithium metal batteries (LMBs) is impeded by lithium dendrite growth and unstable ion transport under high current densities. Herein, we report a high-loading silica composite separator comprising PVDF-HFP, vinyl-modified dendritic mesoporous silica (VDMSNs), and a zwitterionic monomer, VITFSI. Acting as an interfacial compatibilizer, VITFSI ensures the uniform dispersion of VDMSNs even at a high loading of 64 vol%. This homogeneous structure significantly enhances the mechanical modulus while providing nanoconfined pathways for efficient ion transport.
Consequently, the separator delivers a high ionic conductivity of 2.2×10⁻³ S cm⁻¹ and a high lithium-ion transference number of 0.87, attributed to zwitterionic-mediated anion trapping. Li/Li symmetric cells demonstrate stable cycling for over 3,000 h, and Li/LFP full cells exhibit superior capacity retention for 500 cycles even at a high rate of 5C.