Mo₂C/CNT: An Efficient Catalyst for Rechargeable Li–CO₂ Batteries

Abstract

The rechargeable Li–CO 2 battery is a novel and promising energy storage system with the capability of CO 2 capture due to the reversible reaction between lithium ions and carbon dioxide. Carbon materials as the cathode, however, limit both the cycling performance and the energy efficiency of the rechargeable Li–CO 2 battery, due to the insulating Li 2 CO 3 formed in the discharge process, which is difficult to decompose in the charge process. Here, a Mo 2 C/carbon nanotube composite material is developed as the cathode for the rechargeable Li–CO 2 battery and can achieve high energy efficiency (77%) and improved cycling performance (40 cycles). A related mechanism is proposed that Mo 2 C can stabilize the intermediate reduction product of CO 2 on discharge, thus preventing the formation of insulating Li 2 CO 3 . In contrast to insulating Li 2 CO 3 , this amorphous Li 2 C 2 O 4 ‐Mo 2 C discharge product can be decomposed below 3.5 V on charge. The introduction of Mo 2 C provides an effective solution to the problem of low round‐trip efficiency in the Li–CO 2 battery.