Engineering CO₂ Reduction Pathways via Alloy-Support Interactions in Li-CO₂ Batteries.

Abstract

Rechargeable Li-CO₂ batteries (LCBs) hold great promise for dual-function CO₂ utilization and energy storage, yet their practical application is hindered by the sluggish kinetics of the conventional Li₂CO₃ pathway, resulting in low discharge voltages (below 2.0 V) and large overpotentials (over 1.0 V). Herein, we propose a strategy of CO₂ reduction pathway engineering via alloy-support interaction to unlock high-performance LCBs. We designed a Ru₂Cu₄/NC₁₀₀₀ catalyst, where spectroscopy confirms distinct charge redistribution driven by strong coordination between the Ru₂Cu₄ alloy and N-doped support. Theoretical simulations validate that this interaction shifts the Ru and Cu d-band centers toward the Fermi level and induces interfacial charge redistribution, thus optimizing the electronic structure of the Ru-Cu active sites for CO₂ reduction. More importantly, this electronic restructuring thermodynamically favors the formation of metastable Li₂C₂O₄ over insulating Li₂CO₃, thus significantly reducing the activation energy barrier for the rate-determining step by 0.56 eV. As a result, the cell achieves a minimal overpotential of 0.50 V, an exceptional discharge voltage of 3.23 V, and a high specific capacity of 33 922 mAh g^-1 (at 100 mA g^-1). Our work establishes electron-state engineering via alloy-support interactions as a protocol for directing reaction pathways and achieving high-voltage and durable LCBs.