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.