Although non–aqueous lithium–oxygen (Li–O₂) batteries have been gaining attention in recent years for their potentially high energy density, their actual performances are still inferior to that of state–of–the–art Li–ion batteries. To overcome the high overpotential, low rate capability, and poor cycle performance, the development of O₂ electrode structures and catalysts is of great importance. Herein, a graphitic carbon nitride/carbon nanotube composite (GCN/CNT) was synthesized using a facile annealing method and evaluated as a cathode for non–aqueous Li–O₂ batteries, where CNT can provide storage sites for the reactants and products while facilitating electron transfer, and GCN can act as catalytic centers for oxygen reactions.

Due to its large surface area, high nitrogen content and synergistic coupling, GCN/CNT (18 wt.% GCN) demonstrated improved activity and stability towards ORR and OER (ΔE = 1.07 V) compared to pure CNT. Consequently, GCN/CNT exhibited lower overpotential and better cycling stability when applied as a Li–O₂ battery cathode. It delivered a specific discharge capacity of 3796 mA h g^–1 at a current density of 100 mA g^–1, and a relatively stable cycling performance of up to 35 cycles at a limited capacity of 1000 mA h g^–1. Moreover, the reversible formation and decomposition of the Li₂O₂ product after cycling was confirmed in the characterization data (SEM images and XRD patterns). Hence, this GCN/CNT composite could be a promising cathode material in Li–O₂ batteries.

Figure 1. Discharge and charge curves of Li–O₂ battery at a current density of 100 mA g⁻¹ using GCN/CNT cathode. Note: Dashed cycles signal the decline in capacity.