Facile fabrication of Ni, Fe-doped δ-MnO derived from Prussian blue analogues as an efficient catalyst for stable Li-CO batteries.

Rechargeable Li-CO batteries are regarded as an ideal new-generation energy storage system, owing to their high energy density and extraordinary CO capture capability. Developing a suitable cathode to improve the electrochemical performance of Li-CO batteries has always been a research hotspot. Herein, Ni-Fe-δ-MnO nano-flower composites are designed and synthesized by etching a Ni-Fe PBA precursor as the cathode for Li-CO batteries. Ni-Fe-δ-MnO nanoflowers composed of ultra-thin nanosheets possess considerable surface spaces, which can not only provide abundant catalytic active sites, but also facilitate the nucleation of discharge products and promote the CO reduction reaction. On the one hand, the introduction of Ni and Fe elements can improve the electrical conductivity of δ-MnO. On the other hand, the synergistic catalytic effect between Ni, Fe elements and δ-MnO will greatly enhance the cycling performance and reduce the overpotential of Li-CO batteries. Consequently, the Li-CO battery based on the Ni-Fe-δ-MnO cathode shows a high discharge capacity of 8287 mA h g and can stabilize over 100 cycles at a current density of 100 mA g. The work offers a promising guideline to design efficient manganese-based catalysts for Li-CO batteries.