Lifetime of lithium-oxygen battery in limited depth discharge and deep depth discharge cycling modes

The effect of discharge depth on the lifetime of lithium-oxygen batteries (LOBs) is studied under cycling in TEGDME and DMSO media. It is shown that in LOBs based on alkali-treated carbon nanotubes (CNTOH and PtCo/CNTOH) combining high outer surface area, volume, and average diameter of pores, cycling reversibility increases while reducing the amount of discharge product formed on the positive electrode. For LOBs with XC-72, reversibility does not depend on the discharge depth owing to the close values of the smallest Li2O2 particle size and average pore size. For each of the materials, replacement of DMSO by TEGDME allows enhancing the LOB lifetime in the studied cycling modes. For CNTOH and PtCo/CNTOH, ratios are determined that characterize variation of LOB parameters when changing the depth of discharge. The calculated ratios allow predicting the LOB characteristics at a change in the discharge mode or solvent type. (C) 2020 Published by Elsevier B.V.