Boosting the reaction kinetics in aprotic lithium-carbon dioxide batteries with unconventional phase metal nanomaterials.

Zhou, Jingwen; Wang, Tianshuai; Chen, Lin; Liao, Lingwen; Wang, Yunhao; Xi, Shibo; Chen, Bo; Lin, Ting et al. · Proc Natl Acad Sci U S A · 2022

basic_science · Level V

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Abstract

Given the high energy density and eco-friendly characteristics, lithium-carbon dioxide (Li-CO<sub>2</sub>) batteries have been considered to be a next-generation energy technology to promote carbon neutral and space exploration. However, Li-CO<sub>2</sub> batteries suffer from sluggish reaction kinetics, causing large overpotential and poor energy efficiency. Here, we observe enhanced reaction kinetics in aprotic Li-CO<sub>2</sub> batteries with unconventional phase 4H/face-centered cubic (fcc) iridium (Ir) nanostructures grown on gold template. Significantly, 4H/fcc Ir exhibits superior electrochemical performance over fcc Ir in facilitating the round-trip reaction kinetics of Li<sup>+</sup>-mediated CO<sub>2</sub> reduction and evolution, achieving a low charge plateau below 3.61 V and high energy efficiency of 83.8%. Ex situ/in situ studies and theoretical calculations reveal that the boosted reaction kinetics arises from the highly reversible generation of amorphous/low-crystalline discharge products on 4H/fcc Ir via the Ir-O coupling. The demonstration of flexible Li-CO<sub>2</sub> pouch cells with 4H/fcc Ir suggests the feasibility of using unconventional phase nanomaterials in practical scenarios.