A Ga–Sn liquid metal-mediated structural cathode for Li–O2 batteries

Abstract

One of the recent challenges in Li–O2 battery technology is the cycle life, which can be severely shortened by cathode passivation induced by discharge product accumulation; this can be eliminated by reducing the amount of discharge products. Herein, we report a feasibility study on the development of a Ga–Sn liquid metal (LM)-functionalized multiwalled carbon nanotubes (MWNTs) cathode. In a comparison of MWNT, LM, m-LM/MWNT (pre-mixed LM and MWNTs), and LM/MWNT (LM-modified MWNTs) cathodes, morphology analysis showed that small Li2O2 flakes rather than large crystals grow on the conductive Ga–Sn LM and MWNTs of the LM/MWNT cathode only. The decomposition of the flaky Li2O2 on the LM/MWNT cathode occurred at lower charge overpotentials, resulting in low polarization; thus, the cathode passivation and the consumption of the Li anode were both alleviated during the cyclic process. The LM/MWNT cathode significantly improved the cycle life, rate performance, and ultimate capacity of Li–O2 batteries.