Boosting Li-CO2 Battery Performance via High-Entropy Alloy Catalysts: Insights into Configurational Entropy Effect.

Li-CO2 batteries have attracted considerable attention for their ability to combine CO2 fixation and conversion with high-density energy storage. However, sluggish kinetics of CO2 reduction and evolution reactions at cathodes lead to large overpotential and poor cyclic stability. To address this issue, it is critical to develop advanced cathode catalysts. High-entropy alloys (HEAs), a new class of catalysts, have exhibited exceptional catalytic activities in various electrochemical reactions. Nevertheless, the intrinsic relationship between mix configurational entropy (∆Smix) and catalytic properties of HEAs remains unclear. Herein, we prepared a series of quinary FeCoNiCuRu alloys with different ∆Smix values supported on carbon nanofibers as cathode catalysts in Li-CO2 batteries. Experimental and computational results reveal a positive correlation between ∆Smix and catalytic activity, attributed to charge redistribution among elements with different electronegativities. The Li-CO2 battery using the alloy catalyst with the maximum ∆Smix value delivers the largest capacity of 6160 mAh g-1, the lowest charge potential plateau below 4.0 V, and remarkable cycling stability (550 cycles/5500 h), surpassing most reported Ru-based catalysts. Furthermore, fabrication of pouch cells with low noble metal loading demonstrates the practical potential of HEAs for Li-CO2 batteries. This work provides insights into high-entropy engineering for advanced electrocatalysts in Li-CO2 batteries.