Single-metal site-embedded conjugated macrocyclic hybrid catalysts enable boosted CO2 reduction and evolution kinetics in Li-CO2 batteries

Abstract

Rechargeable Li-CO2 batteries, an emerging battery technology to confront the environmental and energy crises, hold promise for CO2 fixation and energy storage. However, state-of-the-art Li-CO2 systems generally suffer from sluggish CO2 reduction/evolution reaction kinetics, and powerful catalysts that can simultaneously facilitate both processes are much desired but largely unrealized. Here, we report a series of Ru, metal-chelated conjugated N4-macrocyclic metal complex (M-CPY) and carbon nanotube (CNT)-based hybrid materials (Ru/[email protected]) with the advantages of highly dispersed Ru and M-CPY, high-conductivity, and tunable loadings that can be applied as multi-functional cathode catalysts. Ru/[email protected] cells deliver an ultra-low overpotential (0.84 V) and enable fully reversible discharge/charge with a high specific capacity of 24,740 mAh/g within 2.0–4.5 V at 200 mA/g. It can rapidly discharge/charge for 180 cycles at 500 mA/g, and the CO2 activation process is intensively investigated by density functional theory (DFT) calculations.