The utilization of the greenhouse gas CO2 in energy-storage systems is highly desirable. It is now shown that the introduction of graphene as a cathode material significantly improves the performance of Li-CO2 batteries. Such batteries display a superior discharge capacity and enhanced cycle stability. Therefore, graphene can act as an efficient cathode in Li-CO2 batteries, and it provides a novel approach for simultaneously capturing CO2 and storing energy.

Lithium–oxygen batteries are attracting more and more interest; however, their poor rechargeability and low efficiency remain critical barriers to practical applications. Herein, hierarchical carbon–nitrogen architectures with both macrochannels and mesopores are prepared through an economical and environmentally benign sol–gel route, which show high electrocatalytic activity and stable cyclability over 160 cycles as cathodes for Li–O2 batteries. Such good performance owes to the coexistence of macrochannels and mesopores in C–N hierarchical architectures, which greatly facilitate the Li+ diffusion and electrolyte immersion, as well as provide an effective space for O2 diffusion and O2/Li2O2 conversion. Additionally, the mechanism of oxygen reduction reactions is discussed with the N‐rich carbon materials through first‐principles computations. The lithiated pyridinic N provides excellent O2 adsorption and activation sites, and thus catalyzes the electrode processes. Therefore, hierarchical carbon–nitrogen architectures with both macrochannels and mesopores are promising cathodes for Li–O2 batteries.

3D hierarchical porous N-rich graphitic carbon materials were prepared and further used for symmetric aqueous supercapacitors with battery-level energy density while retaining capacitor-type power density and cycling stability.

In this work, we present a facile sol-gel method to prepare a composite of Co nanoparticles highly dispersed on N-rich carbon substrates (Co-C composite). The assembled Li-O2 batteries with the composite as a cathode catalyst showed lower overpotential and better cyclability, and the improved performance may be attributed to the superior electrocatalytic activity of the Co-C composite.