Boosting a practical Li-CO2 battery through dimerization reaction based on solid redox mediator

Abstract

Abstract Li-CO 2 batteries offer a promising avenue for converting greenhouse gases into electricity. However, the inherent challenge of direct electrocatalytic reduction of inert CO 2 often results in the formation of Li 2 CO 3 , causing a dip in output voltage and energy efficiency. Our innovative approach involves solid redox mediators, affixed to the cathode via a Cu(II) coordination compound of benzene-1,3,5-tricarboxylic acid. This technique effectively circumvents the shuttle effect and sluggish kinetics associated with soluble redox mediators. Results show that the electrochemically reduced Cu(I) solid redox mediator efficiently captures CO 2 , facilitating Li 2 C 2 O 4 formation through a dimerization reaction involving a dimeric oxalate intermediate. The Li-CO 2 battery employing the Cu(II) solid redox mediator boasts a higher discharge voltage of 2.8 V, a lower charge potential of 3.7 V, and superior cycling performance over 400 cycles. Simultaneously, the successful development of a Li-CO 2 pouch battery propels metal-CO 2 batteries closer to practical application.