Conductive Cu ₃ (HHTP) ₂ Nanorods Anchored on Biomass-Derived Carbon Wood as a Binder-Free Cathode for High-Performance Li-CO₂ Batteries

Abstract

Lithium-CO2 (Li-CO2) batteries have emerged as a promising area of research due to their exceptionally high theoretical energy density and potential for carbon dioxide conversion and utilization. However, their practical application is hindered by several challenges, including the low electrical conductivity of Li2CO3 discharge products, substantial charge discharge polarization, and sluggish kinetics of CO2 reduction and evolution reactions. In this study, one dimensional conductive metal organic framework (Cu3(HHTP)2) nanorods are uniformly anchored onto a carbonized wood (CW) membrane derived from balsa wood via a hydrothermal synthesis method, resulting in the formation of a self standing Cu3(HHTP)2@CW composite cathode. This integrated cathode architecture provides abundant catalytically active sites and facilitates efficient electron and ion transport during electrochemical processes, leveraging the synergistic effects of the highly conductive 1D Cu3(HHTP)2 nanostructures and the hierarchical porous network of biomass derived CW. The Li-CO2 battery incorporating the Cu3(HHTP)2@CW cathode achieves an areal discharge capacity of 13.25 mAh cm -2 at a current density of 50 μA cm⁻², with a narrow voltage gap of 1.06 V. Moreover, the cell exhibits stable cycling performance over 1000 cycles under a fixed capacity of 100 μAh cm⁻² at 100 μA cm⁻². In situ X ray diffraction (XRD), in situ electrochemical impedance spectroscopy (EIS), and distribution of relaxation time (DRT) analyses collectively confirm enhanced charge transfer kinetics and the reversible formation and decomposition of Li2CO3 on the Cu3(HHTP)2@CW cathode. This work presents a sustainable strategy for developing low cost, metal organic framework biomass carbon composites that serve as efficient, binder free cathodes for advanced energy conversion and storage technologies.