Cement/Sulfur for Lithium-Sulfur Cells

Lithium-sulfur batteries represent a promising class of next-generation rechargeable energy storage technologies, primarily because of their high-capacity sulfur cathode, reversible battery chemistry, low toxicity, and cost-effectiveness. However, they lack a tailored cell material and configuration for enhancing their high electrochemical utilization and stability. This study introduces a cross-disciplinary concept involving cost-efficient cement and sulfur to prepare a cement/sulfur energy storage material. Although cement has low conductivity and porosity, our findings demonstrate that its robust polysulfide adsorption capability is beneficial in the design of a cathode composite. The cathode composite attains enhanced cell fabrication parameters, featuring a high sulfur content and loading of 80 wt% and 6.4 mg cm-2, respectively. The resulting cell with the cement/sulfur cathode composite exhibits high active-material retention and utilization, resulting in a high charge storage capacity of 1189 mA∙h g-1, high rate performance across C/20 to C/3 rates, and an extended lifespan of 200 cycles. These attributes contribute to excellent cell performance values, demonstrating areal capacities ranging from 4.59 to 7.61 mA∙h cm-2, an energy density spanning 9.63 to 15.98 mW∙h cm-2, and gravimetric capacities between 573 and 951 mA∙h g-1 per electrode. Therefore, this study pioneers a new approach in lithium-sulfur battery research, opting for a nonporous material with robust polysulfide adsorption capabilities, namely cement. It effectively showcases the potential of the resulting cement/sulfur cathode composite to enhance fabrication feasibility, cell fabrication parameters, and cell performance values.

Atomically Dispersed and O, N-Coordinated Mn-Based Catalyst for Promoting the Conversion of Polysulfides in Li2S-Based Li-S Battery

Nowadays, Li-S batteries are facing many thorny challenges like volume expansion and lithium dendrites on the road to commercialization. Due to the peculiarity of complete lithiation and the capability to match non-lithium anodes, Li₂S-based Li-S batteries have attracted more and more attention. Nevertheless, the same notorious shuttle effect of polysulfides as in traditional Li-S batteries and the poor conductivity of Li₂S lead to sluggish conversion reaction kinetics, poor Coulombic efficiency, and cycling performance. Herein, we propose the interconnected porous carbon skeleton as the host, which is modified by an atomically dispersed Mn catalyst as well as O, N atoms (named as ON-MnPC) via the melt salt method, and introduce the Li₂S nanosheet into the carbon host with poly(vinyl pyrrolidone) ethanol solution. It has been found that the introduction of O, N to bind with Mn atoms can endow the nonpolar carbon surface with ample unsaturated coordination active sites, restrain the shuttle effect, and enhance the diffusion of Li⁺ and accelerate the conversion reaction kinetics. Besides, due to the ultra-high catalyst activity of atomically dispersed Mn catalysts, the Li₂S/ON-MnPC cathode shows good electrochemical performance, e.g., an initial capacity of 534 mAh g^-1, a capacity of 514.18 mAh g^-1 after 100 cycles, a high retention rate of 96.23%, and a decay rate of 0.04% per cycle. Hence, use of atomically dispersed Mn catalysts to catalyze the chemical conversion reactions of polysulfides from multiple dimensions is a significant exploration, and it can provide a brand-new train of thought for the development and commercialization of the economical, high-performance Li₂S-based Li-S batteries.