Sulfur Encapsulation and Sulfur Doping Synergistically Enhance Sodium Ion Storage in Microporous Carbon Anodes

Abstract

MOF-based materials are a class of efficient precursors for the preparation of heteroatom-doped porous carbon materials that have been widely applied as anode materials for Na-ion batteries. Thereinto, sulfur is often introduced to increase defects and act as an active species to directly react with sodium ions. Although the sulfur introduction and high surface area can synergistically improve capacity and rate capability, the initial Coulombic efficiency (ICE) and electrical conductivity of carbon material are inevitably reduced. Therefore, balancing sodium storage capacity and ICE is still the bottleneck faced by adsorbent carbon materials. Here, sulfur-encapsulated microporous carbon material with nitrogen, sulfur dual-doping (NSPC) is synthesized by postprocessing, achieving the reduced specific surface area by encapsulating sulfur in micropores, and the increased active sites by edge sulfur doping. The synergy between encapsulation and sulfur doping effectively balances specific capacity, rate capability, and ICE. The NSPC material exhibits capacities of 591.5 and 244.2 mAh g −1 at 0.5 and at 10 A g −1 , respectively, and the ICE is as high as 72.3%. Moreover, the effect of nitrogen and sulfur on the improvement of electron/ion diffusion kinetics is resonantly demonstrated by density functional theory calculations. This synergistic preparation method may reveal a feasible thought for fabricating excellent-performance adsorption-type carbon materials for Na-ion batteries.

High-Energy Ball Milling Promoted Sulfur Immobilization for Constructing High-Performance Na-Storage Carbon Anodes

“…As for CFG and CFG-S, sluggish electrochemical kinetics due to the intercalation reaction and narrow interlayer spacing leads to rapid capacity loss at high current densities (Figure S18, Supporting Information). The large capacity and high-rate capability of CFG-S-M are considerably superior to those of some reported S-doped carbon materials, including SGHS, NSGFs, NOS-TC100, NSCRs, S-CNF, NSPC, S-CNS, and GF@S-NGC (Figure c). Among these materials, CFG-S-M exhibits a far superior performance because of the unique high-energy ball milling process used for S immobilization.…”

Ni‐Single Atoms Modification Enabled Kinetics Enhanced and Ultra‐Stable Hard Carbon Anode for Sodium‐Ion Batteries

“…In general, these reduction peaks are ascribed to the formation of a solid electrolyte interface (SEI) layer and other irreversible reactions. [20,32] It is worth mentioning that there are significant differences in the voltage range and integrated area of the irreversible reduction peaks between Ni-NPC and NPC, which means that Ni-single atoms have an impact on the formation of SEI layer. The initial three cycles of galvanostatic chargedischarge (GCD) curves at 0.05 A g −1 of Ni-NPC are shown in Figure 3b, where Ni-NPC outputs a reversible specific capacity of 402.1 mAh g −1 with an initial Coulombic efficiency (ICE) of 43.9%.…”

Preparation of Enriched Closed-Pores Hard Carbon for High-Performance Sodium-Ion Batteries by the Poly(vinyl butyral) Template Method

“…Lithium-ion batteries, sodium-ion batteries, and supercapacitors are examples of energy storage technologies. Among these, sodium-ion batteries have garnered significant interest due to the abundance of sodium in the earth’s reserves. − And as an essential component of sodium-ion batteries, research is being conducted on the use of hard carbon as an anode material. − Renewable materials are considered the primary choice for preparing high-performance hard carbon, with cellulose, biowaste, and bamboo all being used to prepare hard carbons, and gained a high initial Coulombic efficiency (ICE) and reversible capacity. However, biomass materials vary tremendously in precursor status due to origin and seasonality.…”