ZIF-67 on Sulfur-Functionalized Graphene Oxide for Lithium–Sulfur Batteries

Abstract

How to overcome the problem of fast capacity fading and low sulfur utilization is the key to promote the practical applications of lithium–sulfur (Li–S) batteries. Based on the fact that sulfur-functionalized graphene oxide (GO-S) can avoid the loss of sulfur/polysulfides through the strong C–S interaction, and the zeolitic imidazolate framework (ZIF-67) can capture sulfur and catalyze lithium polysulfide (Li2S x , 4 ≤ x ≤ 8), the combination of ZIF-S (ZIF-67 after combining with sulfur) with GO-S can be expected to be an excellent electrode material for Li–S batteries due to the synergistic effect. Herein, ZIF-S@GO-S (n) nanocomposites (n = 1, 2, and 3 for the mass ratio of ZIF-67/GO of 4:1, 6:1, and 8:1, respectively) as the cathode materials in Li–S batteries were successfully fabricated, and ZIF-S@GO-S (2) showed better electrochemical performances and cycle stability with a high specific capacity of 1529.5 mA h g–1 at the initial cycle and 792 mA h g–1 after 500 cycles at 0.1 C (1 C = 1675 mA h g–1). The fact that ZIF-S@GO-S (n) can simultaneously improve the conductivity and utilization of S (C–S···S8 and C–S···S x Li2) and the conversion kinetics of Li2S x (4 ≤ x ≤ 8) provides a new avenue for designing and fabricating promising cathodes for high-performance Li–S batteries.

In Situ Generation of Co-Decorated Carbon Nanotubes by Zeolitic Imidazolate Frameworks to Facilitate High-Performance Lithium–Sulfur Batteries

“…Figure f presents the high-resolution spectra of Co 2p. The two peaks appearing at 780.1 and 795.7 eV correspond to the 2p 3/2 and 2p 1/2 orbitals of Co separately. , …”

“…Figure 2a eV correspond to the 2p 3/2 and 2p 1/2 orbitals of Co separately. 30,31 In Figure 3(a-c), the CV tests were performed on the half cells assembled with SP/S, CoNC−CNT/S, and CoNC− CNT/rGO/S electrodes, using Li as the counter electrode. The two cathodic peaks are attributed to the S 8 → LiPSs reaction and LiPSs → Li 2 S 2 /Li 2 S reaction, severally.…”

“…Therefore, ZIFs have been widely studied in the oxygen reduction/evolution reaction, hydrogen evolution reaction, lithium batteries, etc. 20,21 However, the specific surface area of ZIF-derived materials is generally small, and the performance of metal active sites is limited. 22,23 Herein, the cubic form of ZIF-67 is synthesized.…”

“…Zeolitic imidazolate frameworks (ZIFs) are a kind of periodic topological porous material formed by coordination bonds between metal ions and organic ligands. , As precursors, ZIFs can derive metal modified nitrogen–carbon (M-NC) materials, which have a porous 3D carbon structure and deliver plentiful metal active sites. Therefore, ZIFs have been widely studied in the oxygen reduction/evolution reaction, hydrogen evolution reaction, lithium batteries, etc. , However, the specific surface area of ZIF-derived materials is generally small, and the performance of metal active sites is limited. , …”

Bifunctional K3PW12O40/Graphene Oxide-Modified Separator for Inhibiting Polysulfide Diffusion and Stabilizing Lithium Anode

“…Lithium–sulfur (Li–S) batteries are considered as promising candidates for next-generation batteries due to their high theoretical energy density of 2600 Wh kg –1 and low cost of sulfur. − However, the practical application of Li–S batteries is hindered by several challenges. Specifically, the insulative nature of sulfur and the formation of nonconductive discharge products (Li 2 S 2 and Li 2 S) result in sluggish redox reaction kinetics. − Moreover, the “shuttle effect” of dissolved long-chain lithium polysulfide intermediates (Li 2 S n , 4 ≤ n ≤ 8) during the discharge/charge process leads to inferior Coulombic efficiency, abnormal capacity degradation, and the inevitable loss of active material. − To make matters worse, the growth of lithium dendrites arising from uneven Li + stripping/deposition brings a short cycle life and serious safety concerns. , …”