Unraveling Reaction Mechanisms of Mo₂C as Cathode Catalyst in a Li-CO₂ Battery

Abstract

First-principles density functional theory calculations are first used to study possible reaction mechanisms of molybdenum carbide (Mo2C) as cathode catalysts in Li-CO2 batteries. By systematically investigating the Gibbs free energy changes of different intermediates during lithium oxalate (Li2C2O4) and lithium carbonate (Li2CO3) nucleations, it is theoretically demonstrated that Li2C2O4 could be stabilized as the final discharge product, preventing the further formation of Li2CO3. The surface charge distributions of Li2C2O4 adsorbing onto catalytic surfaces are studied by using Bader charge analysis, given that electron transfers are found between Li2C2O4 and Mo2C surfaces. The catalytic activities of catalysts are intensively evaluated toward the discharge and charge processes by calculating the electrochemical free energy diagrams to identify the overpotentials. Our studies promote the understanding of electrochemical processes and shed more light on the design and optimization of cathode catalysts for Li-CO2 batteries.

Promoting the Electrocatalytic Activity of Ti3C2Tx MXene by Modulating CO2 Adsorption through Oxygen Vacancies for High‐Performance Lithium‐Carbon Dioxide Batteries

“…For another, the by‐products generated after the decomposition of electrolyte deposited on the electrode to inhibit the following reactions [9] . Even though some catalysts such as Ti 3 C 2 T x MXene applied in the batteries, they still suffer from a relatively high charge potential and obviously incomplete decomposition of Li 2 CO 3 , leading to a relatively poor electrochemical performance [62–64] . However, thanks to the high catalytic activity of O V ‐TiO 2 /MXene in this work, when the charging process was carried out, the generated discharge products would be completely decomposed and the active sites could be exposed to the reactants again in the Li‐CO 2 batteries with O V ‐TiO 2 /MXene electrodes.…”

Recent Advances in Lithium–Carbon Dioxide Batteries

“…The catalyst was synthesized with a carbothermal reduction methodology. The authors proposed that Mo 2 C could alternate the pathway of producing discharge products and the high activity of Mo 2 C originates from the electronic properties introduced by carbon, which affects the Mo–C binding energy and the reactivity of adsorbates [33a,90] . The produced Li 2 C 2 O 4 with an amorphous feature could be stabilized by forming Li 2 C 2 O 4 –Mo 2 C species (not Li 2 CO 3 ), as shown in Figure a.…”

Nano Polymorphism‐Enabled Redox Electrodes for Rechargeable Batteries

“…Among these metal-air batteries, Li-CO 2 batteries have received significant attention because they reuse CO 2 as a renewable energy carrier and reduce the anthropogenic CO 2 emissions. To date, a wide range of electrocatalysts, such as noble metal nanoparticles, [185] metal-organic frameworks, [186] covalent organic frameworks, [187] metal sulfides, [188,189] metal oxides, [190][191][192][193] metal carbides, [194][195][196] metal phosphides, [197] graphene/CNTs/carbon, [198][199][200][201][202] metal polyphthalocyanines, [203] and metal/carbon hybrids, [204][205][206][207][208][209][210] have been investigated for activating stabilized CO 2 , manipulating the discharge product distribution, and promoting reversibility in Li-CO 2 batteries. The main discharge products of the reduction process in Li-CO 2 batteries include Li 2 CO 3 and carbon.…”