Nanosponge-Based Composite Gel Polymer Electrolyte for Safer Li-O2 Batteries

Li-O-2 batteries represent a promising rechargeable battery candidate to answer the energy challenges our world is facing, thanks to their ultrahigh theoretical energy density. However, the poor cycling stability of the Li-O-2 system and, overall, important safety issues due to the formation of Li dendrites, combined with the use of organic liquid electrolytes and O-2 cross-over, inhibit their practical applications. As a solution to these various issues, we propose a composite gel polymer electrolyte consisting of a highly cross-linked polymer matrix, containing a dextrin-based nanosponge and activated with a liquid electrolyte. The polymer matrix, easily obtained by thermally activated one pot free radical polymerization in bulk, allows to limit dendrite nucleation and growth thanks to its cross-linked structure. At the same time, the nanosponge limits the O-2 cross-over and avoids the formation of crystalline domains in the polymer matrix, which, combined with the liquid electrolyte, allows a good ionic conductivity at room temperature. Such a composite gel polymer electrolyte, tested in a cell containing Li metal as anode and a simple commercial gas diffusion layer, without any catalyst, as cathode demonstrates a full capacity of 5.05 mAh cm(-2) as well as improved reversibility upon cycling, compared to a cell containing liquid electrolyte.

Automated summary

Li-O-2 batteries have high theoretical energy density but are limited by poor cycling stability and safety issues. Researchers have developed a composite gel polymer electrolyte to address these challenges, with a cross-linked structure and nanosponge to improve ionic conductivity.