Topological Defect‐Rich Carbon as a Metal‐Free Cathode Catalyst for High‐Performance Li‐CO₂ Batteries

Abstract

Exploration of the highly efficient bi‐functional catalysts toward the reduction of CO2 and decomposition of Li2CO3 at the cathode is the key for high‐performance Li‐CO2 batteries. Herein, topological defect‐rich graphene (TDG) based materials are developed as metal‐free cathodes for Li‐CO2 batteries, presenting an unprecedented full discharge capacity of over 69 000 mA h g−1 at the current density of 0.5 A g−1, a relatively small voltage gap of 1.87 V (Li/Li+) even at an extremely high current density of 2.0 A g−1, and an excellent long‐term stable cycle life of up to 600 cycles at 1.0 A g−1. The outstanding performance of Li‐CO2 batteries with the TDG cathodic electrocatalyst can be attributed to the introduction of topological defects in the carbon skeleton, providing sufficient active sites for CO2 reduction and evolution to facilitate the formation/decomposition of Li2CO3 during the discharging/charging process. The density functional theory calculations reveal the superiority of the negatively charged C atoms in topological defects as the adsorption for CO2 molecules and the activation sites for the decomposition of Li2CO3, and that the heterocyclic pentagon ring (C5) has a relatively low theoretical potential gap (1.01 V) during the charge and discharge processes.

Electronic State Modulation and Reaction Pathway Regulation on Necklace‐Like MnOx‐CeO2@Polypyrrole Hierarchical Cathode for Advanced and Flexible Li–CO2 Batteries

“…[22] In addition, their nanosized thin shell also ensures good permeability and accessibility, reducing the diffusion resistance in mass transfer. [23] Resulting from the intrinsically poor conductivity and loose macrostructure of most cathodes, [24,25] the developing of highefficiency electrocatalysts is inseparable from the design of reasonable conductive materials as well as the current collectors. Up to date, the general preparation procedure of the cathode for a Li-CO 2 battery is to mix the electrocatalyst, the conductive carbon material and the binder with a certain proportion.…”

Long-life reversible Li-CO2batteries with optimized Li2CO3flakes as discharge products on palladium-copper nanoparticles

“…In a typical aprotic Li-CO 2 battery, a reversible electrochemical reaction 3CO 2 + 4Li ↔ 2Li 2 CO 3 + C can create a high discharge potential of 2.8 V (vs. Li + /Li) and a superior energy density of 1876 W h kg −1 . 1,[7][8][9] During the discharge process, CO 2 is adsorbed and reduced on catalysts, further forming Li 2 CO 3 and C as discharge products. During the charge process, Li 2 CO 3 and amorphous C will be decomposed into CO 2 .…”

“…However, Li 2 CO 3 , as a thermodynamically stable insulator, is hard to be reversibly decomposed and consequently needs a high charge potential to overcome the reaction barrier. 7,[10][11][12] The high charge potential will bring a series of adverse issues, like electrolyte decomposition, cathode corrosion, electrode passivation and so on. Besides, the catalytic sites have been buried for the incomplete decomposition of Li 2 CO 3 and its accumulation on the cathode.…”

Carbon-Based Metal-Free Electrocatalysts: Past, Present, and Future

“…), graphene, and carbon nanotubes after doping with various heteroatoms of different electronegativities from that of carbon atom, , physical adsorption of electron acceptor(s) or donor(s), , and even doping with defect(s), , could exhibit good ORR performance. Furthermore, certain heteroatom-doped C-MFECs have been demonstrated to possess multiple active centers for metal-free bi-/tri-functional (e.g., ORR/OER, ORR/OER/HER) electrocatalysis, holding great potential for metal–air batteries or self-powered water-splitting units, , and even for reduction of CO 2 or N 2 to achieve chemical energy conversion and environmental remediation. − …”

“…Copyright 2019 Nature Publishing Group. (d) Reprinted with permission from ref . Copyright 2021WILEY-VCH.…”