Revisiting the Role of Discharge Products in Li–CO₂ Batteries

Abstract

Rechargeable lithium‐carbon dioxide (Li‐CO2) batteries are promising devices for CO2 recycling and energy storage. However, thermodynamically stable and electrically insulating discharge products (DPs) (e.g., Li2CO3) deposited at cathodes require rigorous conditions for completed decomposition, resulting in large recharge polarization and poor battery reversibility. Although progresses have been achieved in cathode design and electrolyte optimization, the significance of DPs is generally underestimated. Therefore, it is necessary to revisit the role of DPs in Li‐CO2 batteries to boost overall battery performance. Here, we report for the first time, a critical and systematic review of DPs in Li‐CO2 batteries. We appraise fundamentals of reactions for formation and decomposition of DPs and demonstrate impacts on battery performance including, overpotential, capacity and stability, and highlight the necessity of discharge product management. We assess practical in‐situ/operando technologies to characterize reaction intermediates and the corresponding DPs for mechanism investigation. Additionally, achievable control measures to boost the decomposition of DPs are evidenced to provide battery design principles and improve the battery performance. Findings from this work will deepen the understanding of electrochemistry of Li‐CO2 batteries and promote practical applications.This article is protected by copyright. All rights reserved

Graphene nanoribbons/Ru as efficient cathodic catalysts for high-performance rechargeable Li–CO2 batteries

“…However, further investigation showed that DMSO becomes unstable when exposed to superoxide species O 2 ˙ − . 54 Additionally, we use Raman spectroscopy to analyze electrode products at different charging stages and potential by-products have been observed from electrolyte decomposition (Fig. S11, ESI†).…”

“…56,57 It has been reported that the decomposition of Li 2 CO 3 , particularly in the absence of carbon and under high charge overpotential, is a significant pathway for O 2 ˙ − generation. 54 To gain further insights into the electrolyte decomposition, Raman spectroscopy was further used to characterize substances that may be present in the separator (Fig. S11b, ESI†).…”

Reversible and irreversible reaction mechanisms of Li–CO2 batteries

“…Li-CO 2 batteries have garnered extensive attention from the scientic community owing to their high potential for CO 2 xation while simultaneously enabling energy storage with a theoretical energy density of 1876 W h kg −1 . [1][2][3] In contrast to Li-ion batteries, their performance is governed by Li-CO 2 electrochemistry, which operates according to the following reaction: 4Li + 3CO 2 4 2Li 2 CO 3 + C (E 0 = 2.8 V vs. Li/Li + ). [4][5][6][7] However, CO 2 reduction during the discharging process is kinetically sluggish, which results in large discharging overpotentials, and a high charge voltage is also required to decompose the discharge product, Li 2 CO 3 , due to its wide bandgap of 5.03 eV and high thermodynamic stability (DG f = −1132.1 kJ mol −1 ).…”

Upgrading Cycling Stability and Capability of Hybrid Na‐CO2 Batteries via Tailoring Reaction Environment for Efficient Conversion CO2 to HCOOH

“…[ 10 ] In addition, the excellent reversible decomposition capability also ensures high cycle reversibility and low‐temperature operation. [ 11 ] Among the various liquid products of electrochemical reduction of CO 2 , formic acid (HCOOH) emerges as the most competitive target product due to its limited kinetically active proton‐coupled electron transfer processes and a thermodynamically low Nernst potential of −0.2 V RHE . [ 12 ] Consequently, converting solid discharge products into HCOOH is the best way to improve the electrochemical performance of Na‐CO 2 batteries.…”