Unlocking High-Performance Na-CO₂ Batteries via a d-p Orbital Hybridization Descriptor for Rational Catalyst Design

Metal-based catalysts show great promise for efficient Na-CO₂ batteries. However, the absence of a universal principle that connects catalytic properties to battery performance has impeded rational catalyst design. To bridge this gap, we propose a descriptor based on d-p orbital hybridization. Focusing on sodium oxalate (Na₂C₂O₄), a key discharge product with faster decomposition kinetics than carbonates, we systematically investigate the hybridization between metal d-band centers and oxygen p-orbitals, revealing the mechanism governing the formation/decomposition for Na₂C₂O₄. By constructing electronic structure-based theoretical descriptors, we enable efficient prediction and rational design of catalyst performance. The Pd-based catalyst designed using the d-p orbital hybridization descriptor screening strategy enables a battery that achieves a cycling stability of 1800 h with retained energy efficiency of 85.5% and a low overpotential of 0.49 V. The strong correlation between the descriptor and the Gibbs free energy (ΔG) of the rate-determining reaction step confirms its predictive accuracy. This work establishes d-p orbital hybridization as a descriptor for controlling discharge products, guiding the design of high-energy-density Na-CO₂ batteries.