In-situ integration of heterogeneous bilayer composite electrolytes for scalable high-performance lithium-metal batteries

The development of solid-state electrolytes that are simultaneously compatible with both high-voltage cathodes and lithium metal anodes remains a major technical challenge for the practical implementation of solid-state lithium metal batteries. Herein, a heterogeneous bilayer composite electrolyte (HBCE) is developed via an in-situ integration strategy directly on the electrodes. The composite electrolyte integrated with cathode consists of polyvinylidene fluoride-co-hexafluoropropylene, an ionic liquid and Li_6.28La₃Al_0.24Zr₂O₁₂ (LLAZO) nanofibers, while the composite electrolyte integrated with anode is composed of polyethylene glycol methyl ether acrylate, tetraethylene glycol dimethyl ether, and LLAZO nanofibers. This rationally-engineered HBCE structure enables excellent high-voltage stability and effective suppression of lithium dendrite growth. As a result, Li|HBCE|LiFePO₄ (LFP) cells exhibit stable cycling for over 1000 cycles with a maximum capacity of 144.6 mAh g^-1 at 1C, while Li|HBCE|LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cells show a stable cycling performance for more than 200 cycles with a maximum capacity of 151.8 mAh g^-1 at 1C. Moreover, lithium symmetric cells employing the HBCE demonstrate stable charge-discharge cycling exceeding 1500 h at 0.1 mA cm^-2. This work presents an alternate solid-state electrolyte design and in-situ integration strategy that offer promising potential for the scalable production of high-performance solid-state lithium metal batteries.