Metal–CO₂ Electrochemistry: From CO₂ Recycling to Energy Storage

Abstract

Nevertheless, these electrochemical systems usually show unsatisfactory energy conversion efficiency, on account of the thermodynamic stable CO bond in CO 2 molecule (≈806 kJ mol −1 ), endothermic reaction with a high barrier, and multielectron/proton transfer control on the catalyst surface. [13] In this regard, direct CO 2 electrochemical reduction is conducive to capture CO 2 , reduce CO 2 accumulation, boost reaction kinetics, and enhance energy conversion efficiency synchronously. Among all explored systems for CO 2 electrochemical reduction, metal-CO 2 batteries have become a new hotspot because of the independence of real-time electricity input to drive CO 2 conversion [14] and the high energy density of whole cell. Although the research state of these techniques is quite primary, the unique features of fixating CO 2 gas and reserving energy underpin these techniques to alleviate energy issues and climate crises simultaneously. The metal-CO 2 batteries are similar to the electrochemical CO 2 reduction technology in achieving the CO 2 cycle; however, they have the advantage of allowing intermittent electricity input. Furthermore, metal-CO 2 batteries show promising prospects in the future [15] by conversing excessive CO 2 into value-added chemicals, storing surplus electricity from other power supply systems (e.g., fossil fuels, nuclear, and renewable power), and balancing the energy storage and carbon cycle.The origin of metal-CO 2 batteries is based on the addition of CO 2 in Li/Na-O 2 batteries to promote the discharge capacity and energy density. The first article of the primary Li-CO 2 battery with pure CO 2 supply with a nonaqueous electrolyte at moderate temperatures was reported in 2013. [16] Since then, diverse rechargeable metal-CO 2 batteries used various metals anode was constructed and systematically analyzed in the past few years [17] As such, with the introduction of carbon-based materials and metal-based materials, such as graphite, carbon nanotubes (CNTs), and precious metals, as catalysts for the reaction, the performance of metal-CO 2 batteries have been significantly improved, showing great potential in the area of efficient energy storage and electricity supply. [18][19][20][21] After that, the first rechargeable aqueous Zn-CO 2 battery was reported, which can realize the reversible conversion between CO 2 and liquid HCOOH and verified with the application prospects of metal-CO 2 batteries in the production of highly selective carbon-containing compounds. [22] Metal-CO 2 batteries are among the most intriguing techniques for addressing the severe climate crisis and have matured significantly to simultaneously realize adequate fixation of CO 2 , energy storage, and conversion. Although significant efforts have been made, the practical application of metal-CO 2 battery techniques is still restricted by various tremendous challenges, namely high charge potential, poor rate capability, and reversibility. This review seeks to present a realistic assessment of the most advanced metal-CO 2 sy...

Understanding the electrochemical reaction mechanisms of precious metals Au and Ru as cathode catalysts in Li–CO2 batteries

“…6 Nevertheless, the unsatisfactory energy conversion efficiency and poor cycle performance limit the rapid development of Li-CO 2 reversible batteries on account of the thermodynamical stable C]O bonds of the CO 2 molecule ($806 kJ mol À1 ), endothermic reaction with both the extraordinarily high energy barrier and high decomposition voltage of the discharge product (a high charge voltage up to 4.3 V versus Li/Li + ). [7][8][9][10] In other regard, a series of cathode catalysts are subsequently developed to overcome these challenges, such as carbon-based materials (graphite/carbon nanotubes (CNTs)), metal-based materials (precious metals, metal oxides, carbides, suldes), and their derivative compounds. Among these, the charge platform can be realized down to 3.5 V within Mo 2 C/CNTs-based batteries, as reported experimentally, while the cycling stability can achieve long cycling up to 500 cycles with a cut-off capacity of 500 mA h g À1 using MoS 2 nanoakes as the cathode catalyst.…”

Electroreduction of CO2 and Quantification in New Transition-Metal-Based Deep Eutectic Solvents Using Single-Atom Ag Electrocatalyst

“… 3 − 8 The need for long-term CO 2 sequestration cannot be overstated because it can provide CO 2 as a cheap C-1 feedstock for the production of low molecular weight hydrocarbons, 9 platform chemicals, 10 − 14 sustainable energy through electroreduction, 15 , 16 and energy storage. 17 , 18 Therefore, the facile measurement of CO 2 concentration in green solvents is essential to support the mitigation of anthropogenic CO 2 emissions and industrial CO 2 utilization.…”

A Nonaqueous Mg‐CO2 Battery with Low Overpotential

“…In the Mo 2 C‐CNTs composite, Mo 2 C particles could provide highly efficient catalytic active sites for the redox reactions in Mg‐CO 2 batteries, and the CNTs matrix could serve as excellent electronic conducting networks in the cathode relying on their large specific surface area, high conductivity, low cost, and light weight. [ 14a,15,20 ] In fact, the CNTs material itself has been used as a metal‐free catalyst for metal‐CO 2 batteries to improve capacity and prolong cycle life. Moreover, loading Mo 2 C on CNTs could introduce uneven charge distribution and make the nearby carbon atoms positively charged.…”

“…Significant efforts have been made on the development of a variety of catalytic materials to conquer the above‐mentioned challenges, including precious metals (such as Pt, Ru, Au, and Ir), [ 3b,e,7b,12 ] non‐noble metals (such as Mo, Co, Zn, Ni, W, Cu, Ce, and Re), [ 3d,4b–e,g,h,13 ] and non‐metal materials (such as CNTs, B,N‐co‐doped holey graphene, Ketjen Black, and carbon nanofiber). [ 3j,4a,6g,14 ] 2) Although the improvement of reaction kinetics of metal‐CO 2 batteries demonstrates their promising potential to be an efficient energy storage system, [ 3b,4d,7a,15 ] the battery performance is still restricted by other failure mechanisms correlating with the poor discharge/charge reversibility and high charge overpotential. Carbonate, which is believed to be the major discharge product in most metal‐CO 2 batteries, [ 6g,12b,16 ] is a wide‐bandgap insulator with high thermodynamic stability and therefore requires a high decomposition energy.…”