Freestanding molybdenum carbide nanowires electrode for high specific capacity and superior rate performance Li–CO2 batteries

Abstract

Li–CO2 batteries have attracted wide attention owing to unique CO2 capture ability and potential power source for Mars exploration. However, the practical application of Li–CO2 batteries are severely restricted by the sluggish reaction kinetics of 4–electron Li2CO3 as discharged products. Herein, we design efficient freestanding Mo2C nanowires electrode following low electron Li2C2O4–product route to achieve high–performance Li–CO2 batteries. More importantly, we propose a regulation and evolution mechanism of discharge products Li2C2O4 and Li2CO3 on Mo2C cathode in Li–CO2 battery with different discharge depths. Based on reasonable regulation of discharge products, Li–CO2 batteries with the Mo2C nanowires exhibit excellent electrochemical performance with an ultra–low overpotential 0.35 V at 0.05 mA cm–2 and a cycle life of 165 cycles below charge potential of 3.8 V. The Mo2C nanowires electrode also delivers high discharge capacity of 8.47 mAh cm–2 and superior rate capability compared to a conventional Mo2C cathode reported. Moreover, the superior flexibility and stability of the binder–free Mo2C nanowires electrode under different deformations assists in the development of wearable Li–CO2 batteries with safety and sustainability.