An ion-conductive separator for high safety Li metal batteries

Abstract

Li metal anode is promising materials for high-energy-density Li metal batteries (LMBs) due to its large theoretical specific capacity and negative reduction potential. However, the poor safety and insufficient cyclability caused by the dendritic Li growth hinder the commercialization of LMBs. To alleviate the formation of Li dendrites and further improve the cycling stability of LMBs, an ion-conductive polyacrylonitrile (PAN)-based hybrid separator is proposed. The hybrid separator is composed of flexible PAN and high ionic conductive W-doped Li6·3La3Zr1·65W0·35O12 (LLZWO) as the function of physical blocking to realize the Li dendrite-free. As a result, the hybrid separator with 20 wt% LLZWO (PLL-20) shows high ionic conductivity (6.89 × 10−5 S cm−1) and high Li-ion transference number (0.58). The Li|PLL-20|Li symmetric cells exhibit long-term stability without Li dendrite growth at 0.2 mA cm−2 for over 350 h. Furthermore, the Li|PLL-20|LiFePO4 battery delivers a high discharge specific capacity of 138.2 mAh g−1 at 0.2C under ambient conditions. This work highlights the ability of hybrid functional separators to protect Li metal anode in high-energy-density LMBs.