The accumulation of Li 2 CO 3 in a Li-O 2 battery with dual mediators.

One of the most important challenges facing long cycle life Li-O2 batteries is solvent degradation. Even the most stable ethers, such as CH3 O(CH2 CH2 O)CH3 , degrade to form products including Li2 CO3 , which accumulates in the pores of the gas diffusion electrode on cycling leading to polarisation and capacity fading. In this work, we examine the build-up and distribution of Li2 CO3 within the porous gas diffusion electrode during cycling and its link to the cell failure. We also demonstrate that the removal of Li2 CO3 by a redox mediator can partially recover the cell performance and extend the cycle life of a Li-O2 battery.