“Tai Chi” philosophy driven rigid-flexible hybrid ionogel electrolyte for high-performance lithium battery

Dendritic growth of Li metal and its related safety issue in a liquid electrolyte greatly hinder the development of Li metal batteries. Herein, inspired by the Tai Chi philosophy of keeping rigid and flexible balance, we demonstrate a new rigid-flexible hybrid ionogel electrolyte composed of TiO2 rigid framework, PVDF-HFP flexible framework and LiTFSI-Py13TFSI ionic liquid for greatly boosting the performance of Li battery. The as-made hybrid ionogel electrolyte not only has excellent electrochemical properties, such as ionic conductivity up to 7.4 × 10−3 S/cm at 25 °C and anodic stability up to 5.5 V versus Li/Li+, but also has a high mechanical strength to withstand extrusion. These important features make it be able to realize the stable stripping/plating of Li anodes. The hybrid ionogel electrolyte enables the assembled LiFePO4/Li batteries to be successfully cycled at wide C rate (0.1–2.0 C) and exhibit no significant capacity degradation for up to 500 days (about 600 cycles) at a 0.1 C rate. The design from Tai Chi philosophy to protect Li metal opens new opportunities to realize high energy-density Li metal batteries.