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

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Li–CO 2 batteries are of great interest among researchers due to their high energy density and utilization of the greenhouse gas CO 2 to produce energy. However, several shortcomings have been encountered in the practical applications of Li–CO 2 batteries, among which their poor cyclability and high charge overpotential necessary to decompose the highly insulating discharge product (Li 2 CO 3 ) are the most important. Herein, the spinel zinc cobalt oxide porous nanorods with carbon nanotubes (ZnCo 2 O 4 @CNTs) composite is employed as a cathode material in Li–CO 2 batteries to improve the latter’s cycling performance. The ZnCo 2 O 4 @CNT cathode-based Li–CO 2 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 ZnCo 2 O 4 @CNT cathode composite was attributed to the synergistic effects of ZnCo 2 O 4 and CNT. The highly porous ZnCo 2 O 4 nanorod structures in the ZnCo 2 O 4 @CNT catalyst showed enhanced catalytic activity/stability, which effectively promoted CO 2 diffusion during the discharging process and accelerated Li 2 CO 3 decomposition at a low charge overpotential.