Confining Li2O2 in tortuous pores of mesoporous cathodes to facilitate low charge overpotentials for Li-O2 batteries

Abstract

Abstract Achieving low charge overpotentials represents one of the most critical challenges for pursuing high-performance lithium-oxygen (Li-O2) batteries. Herein, we propose a strategy to realize low charge overpotentials by confining the growth of lithium peroxide (Li2O2) inside mesoporous channels of cathodes (CMK-8). The CMK-8 cathode with tortuous pore structures can extend the diffusion distance of lithium superoxide (LiO2) in the mesoporous channels, facilitating the further reduction of LiO2 to lithium peroxide (Li2O2) inside the pores and preventing them to be diffused out of the pores. Therefore, Li2O2 is trapped in the mesoporous channels of CMK-8 cathodes, ensuring a good Li2O2/CMK-8 contact interface. The CMK-8 electrode exhibits a low charge overpotential of 0.43 V and a good cycle life for 72 cycles with a fixed capacity of 500 mAh g−1 at 0.1 A g-1. This study proposes a strategy to achieve a low charge overpotential by confining Li2O2 growth in the mesoporous channels of cathodes.