Mo2N–ZrO2 Heterostructure Engineering in Freestanding Carbon Nanofibers for Upgrading Cycling Stability and Energy Efficiency of Li–CO2 Batteries

Abstract

AbstractLi–CO2 batteries have attracted considerable attention for their advantages of CO2 fixation and high energy density. However, the sluggish dynamics of CO2 reduction/evolution reactions restrict the practical application of Li–CO2 batteries. Herein, a dual‐functional Mo2N–ZrO2 heterostructure engineering in conductive freestanding carbon nanofibers (Mo2N–ZrO2@NCNF) is reported. The integration of Mo2N–ZrO2 heterostructure in porous carbons provides the opportunity to simultaneously accelerate electron transport, boost CO2 conversion, and stabilize intermediate discharge product Li2C2O4. Benefiting from the synchronous advantages, the Mo2N–ZrO2@NCNF catalyst endows the Li–CO2 batteries with excellent cycle stability, good rate capability, and high energy efficiency even under high current densities. The designed cathodes exhibit an ultrahigh energy efficiency of 89.8% and a low charging voltage below 3.3 V with a potential gap of 0.32 V. Remarkably, stable operation over 400 cycles can be achieved even at high current densities of 50 µA cm−2. This work provides valuable guidance for developing multifunctional heterostructured catalysts to upgrade longevity and energy efficiency of Li–CO2 batteries.