Resumption of the discharged Li-AgVO3primary batteries for rechargeable Li-O2batteries

Abstract

Recycling use is one of the energy and resource saving strategies to dispose depleted batteries, especially primary lithium batteries that employ electrode materials based on expensive and low-abundance elements. In this study, we report in detail the recycling use of discharged Li-AgVO3primary battery for rechargeable Li-O2battery. We demonstrate that the discharged Li-AgVO3cell, in which metallic silver nanoparticles in-situ generated in the vanadium oxide nanowires cathode efficiently catalyze the oxygen reduction/evolution reactions (ORR/OER), can be resumed as rechargeable Li-O2cells when they are exposed at O2atmosphere. By controlling the discharge depths, we obtained different cathodes that were composed of vanadium oxide nanowires and silver nanoparticles. As the electrode was discharged to a lower voltage, more silver nanoparticles with larger particle size were distributed on the surface of vanadium oxides, as a result of the sequential reduction of Ag+to Ag0and V5+to V4+. Specifically, the average size of formed Ag nanoparticles was 15 nm and 70 nm at ceased discharge voltage of 2.9 V and 2.0 V, respectively, while the formation of V4+was observed at discharge voltage lower than 2.3 V. Electrochemical tests indicated that the Li-O2cells assembled with the AgVO3cathode discharged to 2.3 V (AgVO3-2.3) exhibited the highest specific capacity (9000 mAh•gcarbon-1), the lowest overpotential and robust cycling performance (up to 95 cycles at the current density of 300 mA•gcarbon-1). The remarkable electrochemical performance of the Li-O2battery with the AgVO3-2.3 cathode is attributed to the optimization of amount, size and distribution of generated silver nanoparticles that contribute to high electronic conductivity and abundant active sites for the ORR/OER. A combined analysis of electrochemical impedance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy confirmed that the AgVO3-2.3 cathode enables the reversible formation and decomposition of Li2O2with lower charge transfer resistance on discharge and charge. The results presented here would provide new insight into the promising recycling application of depleted primary Li-AgVO3batteries in rechargeable high-capacity Li-O2batteries.