Spinel Zinc Cobalt Oxide (ZnCo2O4) Porous Nanorods as a Cathode Material for Highly Durable Li-CO2 Batteries

Li-CO2 batteries are of great interest among researchers due to their high energy density and utilization of the greenhouse gas CO2 to produce energy. However, several shortcomings have been encountered in the practical applications of Li-CO2 batteries, among which their poor cyclability and high charge overpotential necessary to decompose the highly insulating discharge product (Li2CO3) are the most important. Herein, the spinel zinc cobalt oxide porous nanorods with carbon nanotubes (ZnCo2O4@CNTs) composite is employed as a cathode material in Li-CO2 batteries to improve the latter's cycling performance. The ZnCo2O4@CNT cathode-based Li-CO2 battery exhibited a full discharge capacity of 4275 mAh g(-1) and excellent cycling performance over 200 cycles with a charge overpotential below 4.3 V when operated at a current density of 100 mA g(-1) and fixed capacity of 500 mAh g(-1). The superior performance of the ZnCo2O4@CNT cathode composite was attributed to the synergistic effects of ZnCo2O4 and CNT. The highly porous ZnCo2O4 nanorod structures in the ZnCo2O4@CNT catalyst showed enhanced catalytic activity/stability, which effectively promoted CO2 diffusion during the discharging process and accelerated Li2CO3 decomposition at a low charge overpotential.