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-O 2 batteries is solvent degradation. Even the most stable ethers, such as CH 3 O(CH 2 CH 2 O)CH 3 , degrade to form products including Li 2 CO 3 , 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 Li 2 CO 3 within the porous gas diffusion electrode during cycling and its link to the cell failure. We also demonstrate that the removal of Li 2 CO 3 by a redox mediator can partially recover the cell performance and extend the cycle life of a Li-O 2 battery.