Enhancing Electron Conductivity and Electron Density of Single Atom Based Core–Shell Nanoboxes for High Redox Activity in Lithium Sulfur Batteries

Abstract

Herein, an integrated structure of single Fe atom doped core‐shell carbon nanoboxes wrapped by self‐growing carbon nanotubes (CNTs) is designed. Within the nanoboxes, the single Fe atom doped hollow cores are bonded to the shells via the carbon needles, which act as the highways for the electron transport between cores and shells. Moreover, the single Fe atom doped nanobox shells is further wrapped and connected by self‐growing carbon nanotubes. Simultaneously, the needles and carbon nanotubes act as the highways for electron transport, which can improve the overall electron conductivity and electron density within the nanoboxes. Finite element analysis verifies the unique structure including both internal and external connections realize the integration of active sites in nano scale, and results in significant increase in electron transfer and the catalytic performance of Fe‐N4 sites in both Li2Sn lithiation and Li2S delithiation. The Li–S batteries with the double‐shelled single atom catalyst delivered the specific capacity of 702.2 mAh g−1 after 550 cycles at 1.0 C. The regional structure design and evaluation method provide a new strategy for the further development of single atom catalysts for more electrochemical processes.

Theoretical Calculations Facilitating Catalysis for Advanced Lithium-Sulfur Batteries

“…Guo et al verified that introducing single iron atoms into carbon nanoboxes (Fe@C) enhanced electron transport [43]. From the DOS of Fe-N 4 and N-doped carbon (C-N) shown in Figure 2f,g, Fe-N 4 showed more peaks close to the Fermi level than C-N, suggesting that the doped Fe improved the conductivity of C-N.…”

Ultrafine Ni12P5 nanoparticle-embedded carbon with abundant catalytic activity sites as separator modifiers in high-performance lithium–sulfur batteries

“…Lithium-sulfur (Li-S) batteries have an ultra-high theoretical capacity (1675 mA h g −1 ) and are regarded as one of the promising candidates for next-generation energy storage systems. [1][2][3][4][5][6][7] Nevertheless, the large-scale commercialization of Li-S batteries is still subject to various obstacles, including the low conductivity of sulfur and discharge products (Li 2 S and Li 2 S 2 ), large volume expansion, and the shuttle effect of polysulfides, which cause a rapid capacity decay and low coulombic efficiency. [8][9][10][11] To solve such issues, the strategies mainly concentrate on the fortification of the sulfur cathode and lithium anode, electrolyte improvement, and the modification of separators.…”

Cobalt Sulfide Nanoparticles Embedded Carved Carbon Nanoboxes Dispersed in Iron Single-Atom decorated Multiwalled Carbon Nanotube Porous Structure as a Host Material for Lithium–Sulfur Batteries

“…It is evident that several approaches have been developed to improve the electrochemical performances of LSBs, targeting mainly the shuttling effect of polysulfides. These approaches include use of strong polysulfide adsorbents, such as metal sulfides, , incorporation of strong catalysts toward polysulfide conversion reactions, such as single atom catalysts, − ,− and introduction of conductive heteroatom-doped carbonaceous networks to enhance overall electrical conductivities of the cathode and to offer physical confinement to lessen escape of polysulfides. , It is desired to combine all of these approaches to fabricate composite sulfur host materials for LSBs. Such attempts, however, have been rarely, if not never, reported.…”