Alloy/layer double hydroxide interphasic synergy via nano-heterointerfacing for highly reversible CO₂ redox reaction in Li-CO₂ batteries

Li-CO₂ batteries are among the most intriguing techniques for balancing the carbon cycle, but are challenged by the annoyed thermodynamic barrier of the Li₂CO₃ decomposition reaction. Herein, we demonstrate the electrocatalytic performances of two-dimensional (2D) CoAl-layer double hydroxide (LDH) nanosheets can be significantly improved by trans-dimensional crosslinking with three-dimensional (3D) multilevel nanoporous (MP)-RuCoAl alloy (MP-RuCoAl alloy⊥CoAl-LDH). The MP-RuCoAl alloy⊥CoAl-LDH with multiscale pore channels and abundant nano-heterointerface is directly prepared by controllable etching Al from a Ru-Co-Al master alloy along with simultaneous partial oxidization of Al and Co atoms. The MP-RuCoAl is composed of various intermetallic compounds and Ru with abundant grain boundaries, and forms numerous heterointerface with 2D CoAl-LDH nanosheets. The multiscale porous metallic network benefits mass and electron transportation as well as discharge product storage and enables a rich multiphase reaction interface. In situ differential electrochemical mass spectrometry shows that the mass-to-charge ratio in the charging process is ~ 0.733 which is consistent with the theoretical value of 3/4, stating that the reversible co-decomposition of Li₂CO₃ and C can be achieved with the MP-RuCoAl alloy⊥CoAl-LDH. The Ketjen black (KB)/MP-RuCoAl⊥CoAl-LDH battery demonstrates a high cyclability for over 2270 h (227 cycles) with a lower voltage gap stabilized at ~ 1.3 V at 200 mA·g⁻¹. Our findings here provide useful guidelines for developing high efficiency transition metal based electrocatalysts by coupling with conductive porous substrate for impelling the development of practical Li-CO₂ battery systems.