Ultrathin inorganic-organic solid-state electrolyte reinforced by a pre-fiberized LAGP continuous skeleton

Inorganic-organic composite electrolyte is proved an effective way to enhance the overall performance of the electrolytes. However, simply combining powder fillers with polymers is not sufficient for the application of composite electrolytes. In this work, we designed an ultrathin organic-inorganic composite solid electrolyte with high mechanical strength and ionic conductivity, in which the inorganic Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) solid electrolyte is pre-fiberized into a three-dimensional nanofiber network to serve as a self-supporting skeleton for the polyethylene oxide (PEO) matrix. This continuous skeleton structure not only significantly improves the mechanical strength of the PEO-based electrolyte, but also forms a continuous lithium-ion conduction path, promoting the rapid migration of lithium ions. The fiber-reinforced composite electrolyte has an ionic conductivity of 8.27×10⁻⁴ S cm⁻¹ at 60°C and a tensile strength of up to 4.29 MPa. Besides, it exhibits a reduced overpotential and stable long-term cycling performance over 1700 h when used in Li/Li symmetric batteries. The LiFePO₄ (LFP)∣Li cell assembled with the fiber-reinforced composite electrolyte also delivers a specific capacity of about 142 mAh g⁻¹ over 300 cycles at 0.5 C and maintains good cycling stability. This work provides a novel idea for designing the next generation of safe and reliable organic-inorganic composite solid-state electrolyte membranes.