Accelerating the Oxygen Reduction Reaction and Oxygen Evolution Reaction Activities of N and P Co-Doped Porous Activated Carbon for Li-O2 Batteries

Rechargeable lithium-oxygen (Li-O-2) batteries represent state-of-the-art electrochemical energy storage devices that provide high energy densities. However, their commercialization is challenging owing to their low charging/discharging efficiencies, short battery lives, high overpotentials, and high cathode manufacturing costs. In this study, we prepared a metal-free, N,P co-doped, porous activated carbon (N,P-PAC) electrode via KOH activation and P doping for application as a Li-O-2 battery cathode. When used in a rechargeable Li-O-2 battery, the N,P-PAC cathode showed a high specific discharge capacity (3724 mA h g(-1) at 100 mA g(-1)), an excellent cycling stability (25 cycles with a limit capacity of 1000 mA h g(-1)), and a low charge/discharge voltage gap (1.22 V at 1000 mA h g(-1)). The N,P-PAC electrode showed a low overpotential (EOER-ORR) of 1.54 V. The excellent electrochemical performance of the N,P-PAC electrode can mainly be attributed to its large active area and oxygen-containing functional groups generated via KOH activation and P-doping processes. Therefore, the N,P-PAC prepared in this study was found to be a promising eco-friendly and sustainable metal-free cathode material for Li-O-2 batteries.