d-Electrons of Platinum Alloy Steering CO Pathway for Low-Charge Potential Li-CO2 Batteries

Abstract

Aprotic Li-CO₂ batteries suffer from sluggish solid-solid co-oxidation kinetics of C and Li₂CO₃, requiring extremely high charging potentials and leading to serious side reactions and poor energy efficiency. Herein, we introduce a novel approach to address these challenges by modulating the reaction pathway with tailored Pt d-electrons and develop an aprotic Li-CO₂ battery with CO and Li₂CO₃ as the main discharge products. Note that the gas-solid co-oxidation reaction between CO and Li₂CO₃ is both kinetically and thermodynamically more favorable. Consequently, the Li-CO₂ batteries with CoPt alloy-supported on nitrogen-doped carbon nanofiber (CoPt@NCNF) cathode exhibit a charging potential of 2.89 V at 50 μA cm^-2, which is the lowest charging potential to date. Moreover, the CoPt@NCNF cathode also shows exceptional cycling stability (218 cycles at 50 μA cm^-2) and high energy efficiency up to 74.6 %. Comprehensive experiments and theoretical calculations reveal that the lowered d-band center of CoPt alloy effectively promotes CO desorption and inhibits further CO reduction to C. This work provides promising insights into developing efficient and CO-selective Li-CO₂ batteries.

Keywords: Electrochemical CO2 reduction; Li-CO2 batteries; Pt-based catalysts; Reaction pathway; d-band center.