C–S Bonds in Sulfur-Embedded Graphene, Carbon Nanotubes, and Flake Graphite Cathodes for Lithium–Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries are excellent rechargeable battery candidates which are extraordinarily promising as they exhibit superior specific capacity and well-known energy density; they are cost-effective and environmentally benign. Nevertheless, a few technical issues pose a significant challenge on the path to industrial applications, namely, capacity fade and Coulombic efficiency decay, which are inherent in the soluble polysulfide shuttle effect during charge/discharge cycling. Carbon materials which have excellent conductive scaffold and flexible structure with a variety of morphologies can serve as a remedy to this issue. Herein, with a well-designed melt-diffusion procedure, we prepared three carbon-based sulfur-embedded cathodes with diverse structures [graphene, carbon nanotubes (CNTs), and flake graphite]. Sulfur loading varies between 60 and 73 wt %. Among these three carbon/S cathodes, beyond 100 cycles, the graphene/S cathode showed a discharge capacity of 840 mA h g–1 at 0.2 A g–1 current density and its average Coulombic efficiency was above 99.4%, demonstrating the best cycle stability and reversibility. While at a higher current rate, 1 A g–1, CNT/S reaches the best capacity of 518 mA h g–1 among these three cathodes, revealing excellent sulfur utilization under high rate conditions. The X-ray photo spectroscopy shows evidence for chemical bonding between graphene/CNTs surfaces and carbonyl, hydroxyl, and ether groups, resulting in well-confined polysulfides in the cathode side, which significantly restrain the movement of soluble polysulfide in the charging process and efficiently decreases the capacity fading of sulfur. This unique structure is a potential explanation for the outstanding electrochemical performance.

Microporous Carbon Nanoparticles for Lithium–Sulfur Batteries

“…To further study the surface area and the porous structure of the carbonized materials, N 2 adsorption–desorption analysis was performed. The N 2 adsorption–desorption isotherm of the GL-I-800 shows a type III isotherm indicating the nonhomogeneous mesoporous systems ( Figure 1 h) [ 29 ]. The BET (Brunauer–Emmett–Teller) surface area and the pore volume of GL-I-800 are 844 m 2 g −1 and 1.6 cm 3 g −1 , respectively.…”

“…Interconnected porous CNT promotes lithium-ion diffusion and electrical conductivity [ 28 ]. A study compared and examined polysulfide’s confinement ability by introducing sulfur into distinct types of carbon structures such as graphene, flake graphite, and CNTs [ 29 ]. Graphene/S showed the best cycle stability and reversibility at a low current density.…”

Advances in the Applications of Graphene-Based Nanocomposites in Clean Energy Materials

“…The composition, thermal stability and possible intermediate products could be obtained by analyzing the thermogravimetric curve [44]. Feng et al [46] studied three graphene materials with different structures as the cathode of lithium-sulfur batteries. Pure sulfur has the characteristic of one-step weight loss in the temperature range of 190-300 • C by TGA.…”

Molecular Tuning of the Nano–Bio Interface: Alpha-Synuclein’s Surface Targeting with Doped Carbon Nanostructures

“…Some of these nanoparticles can promote amyloid formations by acting as a critical nucleus, while other nanoparticles can prevent the formation of amyloid fibrils by disrupting the amyloid’s secondary structure or acting as chaperones. , Chaperones are particles that help proteins retain their natural formation, prevent protein aggregation, and form a central nucleus . It was observed that nanoparticles such as graphene quantum dots, iron oxide nanoparticles, gold nanoparticles, and amine-functionalized mesoporous silica nanoparticles can inhibit the amyloid formation and can be utilized for developing a cure for PD. − In addition, it has been shown that graphene can destabilize α-synuclein amyloids and prevent aggregation. , …”

“…12−17 In addition, it has been shown that graphene can destabilize α-synuclein amyloids and prevent aggregation. 18,19 Given the importance of preventing the folding and aggregation of α-synuclein that cause amyloid formation prevention, it is imperative to work more on novel structures for PD treatment. Doped carbon nanomaterials are highly tunable and can be optimized to enhance their interaction capabilities using several dopants.…”