Graphene-based quasi-solid-state lithium–oxygen batteries with high energy efficiency and a long cycling lifetime

An aprotic lithium–oxygen battery with an ultrahigh theoretical energy density has attracted significant attention as the next-generation electrochemical energy device demanded by all-electric vehicles and other high-energy devices. Extensive effort has recently been devoted to improving the performances of cathodes, anodes, and electrolytes. However, as an integrated system, the overall battery properties are not determined by the individual components but by the synergy of all components. Despite important progress in the development of cathodes, anodes, and electrolytes, the system-level design and assembly of lithium–oxygen batteries have not benefited from these recent advances. Here, we report a graphene-based quasi-solid-state lithium–oxygen battery consisting of a rationally designed 3D porous graphene cathode, redox mediator-modified gel polymer electrolyte, and porous graphene/Li anode. This integrated prototype battery simultaneously addresses the major challenges of lithium–oxygen batteries and achieves stable cycling at a large capacity, low charge overpotential and high rate in both coin-type and large-scale pouch-type batteries. For the first time, these lithium–oxygen batteries as a whole device deliver gravimetric and volumetric energy densities higher than those of a commercial Li-ion polymer battery. This study represents important progress toward the practical implementation of full-performance lithium–oxygen batteries.