Lithium peroxide crystal clusters as a natural growth feature of discharge products in Li–O 2 cells

The often observed and still unexplained phenomenon of the growth of lithium peroxide crystal clusters during the discharge of Li–O 2 cells is likely to happen because of self-assembling Li 2 O 2 platelets that nucleate homogeneously right after the intermediate formation of superoxide ions by a single-electron oxygen reduction reaction (ORR). This feature limits the rechargeability of Li–O 2 cells, but at the same time it can be beneficial for both capacity improvement and gain in recharge rate if a proper liquid phase mediator can be found.