Highly Efficient Cu-Porphyrin-Based Metal-Organic Framework Nanosheet as Cathode for High-Rate Li-CO 2 Battery.

The lithium-carbon dioxide (Li-CO 2 ) battery as a novel metal-air battery has a high specific energy density and unique CO 2 conversion ability. However, its further development is limited by incomplete product decomposition resulting in poor cycling and rate performance. In this work, Cu-tetra(4-carboxyphenyl) porphyrin (Cu-TCPP) nanosheets are prepared through the solvothermal method successfully. An efficient Li-CO 2 battery with Cu-TCPP as catalyst achieves a high discharge capacity of 20393 mAh g -1 at 100 mA g -1 , a long-life cycle of 123 at 500 mA g -1 , and a lower overpotential of 1.8 V at 2000 mA g -1 . Density functional theory calculation reveals that Cu-TCPP has higher adsorption energy of CO 2 and Li 2 CO 3 compared with TCPP, and a large number of electrons gather near the Cu-N 4 active sites in Cu-TCPP. Therefore, the excellent CO 2 capture ability of the porphyrin ligand and the synergic catalytic effect of Cu atom in Cu-TCPP promote the thermodynamics and kinetics of CO 2 reduction and evolution processes.