A novel NiFe@NC-functionalized N-doped carbon microtubule network derived from biomass as a highly efficient 3D free-standing cathode for Li-CO2 batteries

Rechargeable Li-CO2 batteries, which utilize CO2 into electrochemical energy storage systems, provide a promising strategy for alleviating the greenhouse effect and developing high energy density second batteries. However, problems such as poor battery performance and short cycle life still hinder the development of Li-CO2 batteries. In this work, a novel three-dimensional free-standing NiFe@NC/PPC cathode is prepared by depositing NiFe-Prussian blue analogues on the surface of pomelo peels (PP) and subsequently calcining at high temperature. The products fully retained the three dimensional porous characteristic of biomass, conducing to mass transfer and diffusion. In addition, the high catalytic activity of NiFe@NC is carried forward. Combined with these two advantages, the Li-CO2 battery with NiFe@NC/PPC cathode exhibits a superior discharge capacity of 6.8 mA h cm(-2) and can sustain 109 cycles with a cutoff capacity of 0.25 mA h cm(-2) at a current density of 0.05 mA cm(-2). Overall, this study provides a promising way for the fabrication of environmentally friendly and inexpensive cathodes to improve the performance of Li-CO2 batteries.