MOF‐Derived CoSe₂ Nanoparticles/Carbonized Melamine Foam as Catalytic Cathode Enabling Flexible Li–CO₂ Batteries with High Energy Efficiency and Stable Cycling

Abstract

Rechargeable aprotic Li–CO2 batteries have aroused worldwide interest owing to their environmentally friendly CO2 fixation ability and ultra‐high specific energy density. However, its practical applications are impeded by the sluggish reaction kinetics and discharge product accumulation during cycling. Herein, a flexible composite electrode comprising CoSe2 nanoparticles embedded in 3D carbonized melamine foam (CoSe2/CMF) for Li–CO2 batteries is reported. The abundant CoSe2 clusters can not only facilitate CO2 reduction/evolution kinetics but also serve as Li2CO3 nucleation sites for homogeneous discharge product growth. The CoSe2/CMF‐based Li–CO2 battery exhibits a large initial discharge capacity as high as 5.62 mAh cm−2 at 0.05 mA cm−2, a remarkably small voltage gap of 0.72 V, and an ultrahigh energy efficiency of 85.9% at 0.01 mA cm−2, surpassing most of the noble metal‐based catalysts. Meanwhile, the battery demonstrates excellent cycling stability of 1620 h (162 cycles) at 0.02 mA cm−2 with an average overpotential of 0.98 V and energy efficiency of 85.4%. Theoretical investigations suggest that this outstanding performance is attributed to the suitable CO2/Li adsorption and low Li2CO3 decomposition energy. Moreover, flexible Li–CO2 pouch cell with CoSe2/CMF cathode displays stable power output under different bending deformations, showing promising potential in wearable electronic devices.