Research / 2020 / Article / Fig 2

Research Article

Selective Adsorption and Electrocatalysis of Polysulfides through Hexatomic Nickel Clusters Embedded in N-Doped Graphene toward High-Performance Li-S Batteries

Figure 2

Structural characterizations and theoretical calculations. (a) Raman spectra and (b) N2 adsorption/desorption isotherms of Ni-N/G, N/G, Ni-N/C, and GNs. (c) Ni -edge XANES spectra (inset, the enlarged spectra of Ni porphyrin and Ni-N/G) and (d) Ni -edge -weighted FT-EXAFS spectra of Ni foil, NiO, and Ni porphyrin and Ni-N/G. Experimental testing and theoretical simulation of the polysulfide adsorption and conversion ability of Ni-N/G. (e) XPS S 2p spectra of Li2S6 and Li2S6/Ni-N/G. (f) Structure of Ni6-N/C used in first-principle calculations. (g) Binding geometric configurations and binding energies of sulfur species with the N/G and Ni-N/G. The high binding energies indicate the strong adsorption of Ni-N/G with sulfur species. (h) The binding energies between different lithium polysulfides and adsorbent materials, based on Ni-N/G compared with other currently reported sulfur host materials in the literature. Energy unit: electronvolts. Zero-point corrected.