Lithium garnet incorporated 3D electrospun fibrous membrane for high capacity lithium-metal batteries

Abstract

A new class of electrolytes with enhanced flexibility, high lithium ion (Li+) conductivity, excellent electrochemical stability, good cyclic ability and improved safety are crucial for high performance of lithium-metal batteries. Composite polymer electrolytes assist in overwhelming safety-related issues faced by Li+ batteries with organic liquid electrolytes. Herein, we report on polymer nanocomposite electrospun fibrous membranes (PNEFM) comprising of Li6.28Al0.24La3Zr2O12 (LLZA) garnet oxide nano-fillers in poly (vinylidene fluoride-co-hexafluoropropylene) P(VDF-HFP) co-polymer prepared by electrospinning technique. Li+ conductivity of the PNEFM is remarkably improved by the addition of LLZA garnet filler. The PNEFM-8 (with 8 wt% of LLZA) exhibits a maximized Li+ conductivity of 2.25 × 10−3 S cm−1 at room temperature (25 °C). The PNEFM-8 exhibits a wide electrochemical potential window up to 5.5 V. A full cell with Li||PNEFM-8||LiFePO4 configuration at 25 °C displayed first discharge capacity of 160 mA h g−1 and a reversible discharge capacity of 145 mA h g−1 for 100th cycle at 0.1 C with Coulombic efficiency of 98.78%. Furthermore, PNEFM-8, integrated with composite sulphur cathode exhibits an excellent first discharge capacity of 1311 mA h g−1 and a reversible discharge capacity of 1105 mA h g−1 after 10th cycles with 98.30% Coulombic efficiency. The present study could contribute towards the development of higher performance and safe room temperature Li-metal batteries.