Long-life reversible Li-CO2 batteries with optimized Li2CO3 flakes as discharge products on palladium-copper nanoparticles

Li-CO2 batteries have attracted lots of attention owing to their high working potential and large theoretical energy density, while they still suffer from the sluggish kinetics of CO2 reduction and evolution reactions. Previous research studies on catalysts for photo/electrochemical CO2 reduction have inspired the potential application of copper-based catalysts in Li-CO2 batteries. However, metallic Cu is easy to be oxidized and forms a passivation layer, leading to decreased active sites. Here, we demonstrate PdCu decorated nitrogen doped carbon nanofiber (PdCu/N-CNF) as a stable and efficient cathode for high-performance Li-CO2 batteries. The PdCu/N-CNF cathode delivers a large discharge capacity of 18 550 mA h g(-1) at 100 mA g(-1), and cycles for 1350 h with the lowest discharge/charge polarization of 1.17 V in a limited capacity of 1000 mA h g(-1) at 400 mA g(-1). The ex situ analysis shows that flake-like Li2CO3 is formed through conformal growth instead of large bulk particles. Besides, the oxidation of Cu in the PdCu/N-CNF cathode has been effectively suppressed during the discharge/charge process. Therefore, bimetallic alloys can not only enhance the stability of Cu-based metal materials, but also improve the catalytic properties with the synergistic effect of the two elements.

Automated summary

This study demonstrates the use of PdCu/N-CNF as a stable and efficient cathode for high-performance Li-CO2 batteries. The PdCu/N-CNF cathode delivers a large discharge capacity and cycles for a long duration, while effectively suppressing the oxidation of copper.