Medium-Entropy Alloy/In Situ N-doped rGO Catalyst Composite for Ultrahigh Discharge Capacity and High-Rate...

The immense potential of Li─CO₂ batteries in mitigating CO₂ emissions makes them an attractive choice for developing next-generation high-energy-density alternative energy storage systems. However, insufficient Li₂CO₃ decomposition during recharging deactivates the catalyst, reducing the dischargeability and cycle life. Herein, a medium-entropy quaternary alloy (QA) catalyst comprising of the metals Mn, Zn, Co, and Ni is designed with in situ N-doped reduced graphene oxide (NrGO) using a multielement metal organic framework (MZIF) (QA@NrGO). The uniformly dispersed quaternary alloy with high disorder and the synergy between the NrGO and QA help Li─CO_2Mars batteries deliver an ultrahigh discharge capacity of 50605 mAh g^-1 at the high current density of 500 mA g^-1 and a maximum cycle life of 240 cycles. Ex situ post-cycling physicochemical investigations reveal the formation of disc-shaped Li₂CO₃ discharge product on the active sites and nearly complete decomposition on charging, confirming the excellent reversibility. Further, the density functional theory (DFT) studies show that improved CO₂ adsorption and the tendency toward relatively stable formation of the discharge products of Li₂CO₃ and amorphous carbon helped achieve the excellent electrochemical performance. The designed medium entropy alloy (MEA) catalyst provides a pathway for developing low-cost, highly active bifunctional catalysts for Li─CO_2Mars batteries.