A Liquid Anode of Lithium Biphenyl for Highly Safe Lithium‐Air Battery with Hybrid Electrolyte

Abstract

AbstractA hybrid electrolyte, by uniting aqueous and organic electrolyte with a water‐stable lithium super ionic conductor ceramic (LISICON) plate, was proposed to circumvent the drawbacks of nonaqueous Li‐air batteries, such as corrosion of metallic Li from humidity, decomposition of organic solvents and insoluble discharge products clogging air electrode. However, safety issues deteriorate when the brittle ceramic plate fails to separate organic and aqueous solutions. This study aimed to improve the safety of the hybrid electrolyte based Li‐air battery, by designing a liquid anode of lithium biphenyl (LiBP) replacing the lithium metal as the mild reaction between LiBP and aqueous electrolyte without combustion. Moreover, sputtering Ti layer onto the anodic side of the ceramic plate can improve chemical stability of interface between the liquid anode and solid electrolyte. In this system, the cell exhibited a relatively high discharge voltage of 2.81 V at the current density of 0.5 mA cm−2, as well as a specific power of 1638 W kg−1 at the current density of 6 mA cm−2 by using this liquid anode. The cycling life exceeded over 120 cycles at the current density of 0.5 mA cm−2. The ex situ Raman spectrometry and in situ GC‐MS analyses reveal that the redox reaction of BP−/BP and OH−/O2 in anolyte and catholyte respectively can deliver large capacity during cycling.