Delicate design of lithium-ion bridges in hybrid solid electrolyte for wide-temperature adaptive solid-state lithium metal batteries

Abstract

Hybrid solid electrolytes have emerged as promising candidates for next-generation high-energy-density solid-state lithium metal batteries owing to the enhanced safety and processability. Nevertheless, the practical implementation remains hindered by severe interfacial Li⁺ transport barriers at ceramic-polymer junctions, particularly under ambient low-temperature or high-power-density surroundings. Herein, the lithium-ion bridge concept has been proposed to accelerate Li⁺ transport kinetics across the ceramic-polymer interphase through the delicate design of a chemical bonding strategy. As demonstrated, the poly(vinylidene fluoride-co-hexafluoropropylene) (PH) chain with Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) particles can be connected by lithium benzene sulfonate as Li⁺ conductive bridges. With these Li⁺ bridges, this unique hybrid PH-LLZTO solid-state electrolyte exhibits an exceptional ionic conductivity of 0.71 mS cm⁻¹ at 25°C with a superior Li⁺ transference number of 0.67. Impressively, this advanced solid-state electrolyte empowers high-voltage LiNi_0.8Co_0.1Mn_0.1O₂/Li cells under fast charge/discharge capability as high as 4C and a wide temperature range from −20°C to 60°C. Consequently, the optimal solid-state Li metal battery could stabilize at −20°C with a high discharge specific capacity of 130 mAh g⁻¹. Moreover, a bipolar pouch cell by stacking 4 units can be successfully assembled using this advanced solid-state electrolyte with fast Li⁺ transport kinetics and delivers an ultra-high voltage of 15.12 V, showcasing the great potential of integrated module application in the future.