Anion-Solvent Dual-Sieving Effect Revolutionizes Li Deposition Kinetics for Garnet-Based Solid-State Lithium...

Solid-state batteries (SSBs) are promising candidates for next-generation energy storage due to their high theoretical energy density. However, their practical application is hindered by Li/solid-state electrolyte interfacial issues, including poor contact, lithium dendrites, and side reactions, while polarization under high current densities or areal capacities cannot be ignored. Herein, we report a multifunctional composite interlayer (BN-ASDSI) composed of a flexible polymer scaffold, a sultone-based electrolyte, and boron nitride (BN) to address these challenges. Benefiting from the Lewis acid-base interaction, BN-ASDSI exhibits an anion-anchoring effect that induces a localized microelectric field, accelerating Li⁺ transport while restricting anion mobility. Concurrently, the solvent-repelling property of BN mitigates interfacial side reactions, synergistically promoting the formation of LiF-rich inorganic solid-state interface to stabilize the Li metal. Notably, the symmetric cell with BN-ASDSI achieves an ultrahigh critical current density of 8.8 mA cm^-2. Most impressively, the LiFePO₄ SSB delivers stable operation for 1500 cycles at 6 C with a capacity retention >92%, while the high-loading LiNi_0.83Co_0.12Mn_0.05O₂ (17.2 mg cm^-2) SSB exhibits a high discharge areal capacity of 3.2 mAh cm^-2 at 1 C and retains 93% capacity after 80 cycles at 0.33 C, showcasing the practical potential of BN-ASDSI enabled SSBs.