Boosting the electrochemistry of Li2O2 in lithium–oxygen batteries by plasmon-induced hot-electron injection

Abstract

A photo-assisted Li–oxygen (Li–O₂) battery with Au/SnO₂ (ASO) hybrid nanotubes as the cathode and photocatalyst has been prepared. The localized surface plasmon resonance (LSPR) excitation of gold nanoparticles (Au NPs) can dramatically improve the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of Li–O₂ batteries. The photoelectrons generated via LSPR can be transferred to the conduction band (CB) of SnO₂ for facilitating the reduction of O₂ to form Li₂O₂ through the ORR, in a discharge process with illumination. Conversely, the holes left in Au NPs can promote Li₂O₂ oxidation in a charging process with illumination. With illumination, a 2.36 times higher discharge capacity of up to 10705.2 mA h g⁻¹ is observed and the discharged product (Li₂O₂) can be decomposed completely due to LSPR. The discharge voltage can be obviously enhanced to 3.10 V, significantly exceeding the equilibrium voltage of 2.96 V, and the charge voltage is decreased to 3.59 V. This work provides a new strategy for the decomposition of Li₂O₂ by improving the efficiency of charge transfer dynamics and the mechanism of LSPR in the photo-assisted (Li–O₂) battery.