Understanding the Catalytic Activity of the Preferred Nitrogen Configuration on the Carbon Nanotube Surface and Its Implications for Li–O₂ Batteries

Abstract

Unraveling the catalytic potential of nitrogen-doped carbon nanotubes (NCNTs) for the electrochemical reaction in a Li−O 2 battery (LOB) is of great significance for the preparation of highly active catalysts to overcome the sluggish kinetics. Herein, the surface properties, reaction mechanism, and product behavior on NCNT cathodes are investigated for LOBs using periodic density functional theory. Our calculations demonstrate that the electron-withdrawing nature of N atoms shortens the surrounding N−C and C−C bonds by arranging the electron distribution on the NCNT surface. The conversion from the p-type semiconductor to n-type semiconductor or metallic characteristics occurs between pristine CNTs (PCNTs) and NCNTs. Surprisingly, NCNTs exhibit enhanced adsorption for Li x O y in comparison with PCNTs. The lithiation reaction is the primary contributor to the formation of Li 2 O 2 and Li 2 O on the surfaces of both PCNTs and NCNTs. Meanwhile, tri-N and tetra-N NCNTs promote the growth of Li 2 O 2 and inhibit the further reduction of Li 2 O 2 to Li 2 O, alleviating the passivation of the cathode surface. Our study achieves a deeper understanding of the catalytic mechanism of NCNTs and provides hints for the design of high-efficiency catalysts for Li−O 2 and other potential batteries.

Completely Eradicating Singlet Oxygen in Li–O2 Battery via Cobalt(II)-Porphyrin Complex-Catalyzed LiOH Chemistry

“…However, the ratio of Li 2 CO 3 on the fully charged electrodes shows a significant decreasing trend for pristine and TAPP- and Co-TAP-containing batteries (80.2%, 44.3%, and 17.6%, respectively, Figure S5a–c), indicating that parasitic reactions are suppressed by adding TAPP or Co-TAP RMs, especially Co-TAP. Generally, Li 2 O is reported to be not easily decomposed during charging in LOBs . However, for both pristine and TAPP-containing batteries in this study, Li 2 O disappears entirely after charging.…”

“…Generally, Li 2 O is reported to be not easily decomposed during charging in LOBs. 38 However, for both pristine and TAPP-containing batteries in this study, Li 2 O disappears entirely after charging. These results were also confirmed by Li 1s XPS spectra (Figure S6a−c).…”

Recent strategies for improving the performances of rechargeable lithium batteries with sulfur- and oxygen-based conversion cathodes

“…With this in mind, various physical and chemical modifications, such as heteroatom doping, have been applied to improve the catalytic activity of carbon materials. The charge redistribution caused by the difference in electronegativity between heteroatoms and carbon atoms can impart carbon with a whole new electrochemical property [84] . Yi et al found through calculations using periodic density functional theory that doping N atoms on the surface of CNTs affects both the atomic distribution and electrical conductivity.…”

“…In addition to carbon compounds doped with heteroatoms such as N and P, there are rarely reported carbon materials doped with F [84] . Due to the high electronegativity of F, the semi-ionic C-F bond produced by F renders the carbon doped with F acidic and appears as an electron acceptor, leading to an extremely stable material with enhanced electron transfer capability [86,87] .…”

Evolution of Discharge Products on Carbon Nanotube Cathodes in Li–O2 Batteries Unraveled by Molecular Dynamics and Density Functional Theory

“…Considering that the specific behavior of lithium oxides in LOBs is difficult to be tracked and captured, the inadequacies of the experiment are inevitably highlighted. In recent years, micro-theoretical calculations, mainly including density functional theory (DFT) and molecular dynamics (MD), have become one of the indispensable research methods in revealing reactions, interfaces, and interactions. ,− Computations not only provide important insights into the electrochemical mechanism but also shed more light on the design and improvement of experimental programs and material preparation.…”