A novel sulfur@void@hydrogel yolk-shell particle with a high sulfur content for volume-accommodable and polysulfide-adsorptive lithium-sulfur battery cathodes

Abstract

High-energy-density secondary batteries are required for many applications such as electric vehicles. Lithium-sulfur (Li-S) batteries are receiving broad attention because of their high theoretical energy density. However, the large volume change of sulfur during cycling, poor conductivity, and the shuttle effect of sulfides severely restrict the Li-storage performance of Li-S batteries. Herein, we present a novel core-shell nanocomposite consisting of a sulfur core and a hydrogel polypyrrole (PPy) shell, enabling an ultra-high sulfur content of about 98.4% within the composite, which greatly exceeds many other conventional composites obtained by coating sulfur onto some hosts. In addition, the void inside the core-shell structure effectively accommodates the volume change; the conductive PPy shell improves the conductivity of the composite; and PPy is able to adsorb polysulfides, suppressing the shuttle effect. After cycling for 200 cycles, the prepared S@void@PPy composite retains a stable capacity of 650 mAh g −1 , which is higher than the bare sulfur particles. The composite also exhibits a fast Li ion diffusion coefficient. Furthermore, the density functional theory calculations show the PPy shell is able to adsorb polysulfides efficiently, with a large adsorption energy and charge density transfer.

A General Template‐Induced Sulfuration Approach for Preparing Bifunctional Hollow Sulfides for High‐Performance Al‐ and Li‐ion Batteries

“…The preparation of sulfur particles was close to our previous report [ 40 ] with some modifications. All chemicals were purchased from Sinopharm Chemical Reagent Co., Ltd. First, 200 mL of deionized water, 1.265 g of sodium thiosulfate, 0.285 g of sodium lauryl sulfate were mixed in a 200 mL beaker at 30 ºC.…”

Conducting Polymers Meet Lithium–Sulfur Batteries: Progress, Challenges, and Perspectives

“…For a clearer presentation of the cycling performance of the previously reported PPy‐based materials in the cathode of Li–S batteries, the initial capacity and the capacity retention ability of various PPy‐based materials using in different components (coating layer, sulfur host, precursor, and binder) of the cathode are comprehensively summarized in Figure and Table S1, Supporting Information. [ 45–47,82–124 ] The capacity retention is an important factor to evaluate the battery performance of CPs. As shown in Figure 3, PPy doped with superior conductive mediums (metal compound, MOF, etc) will deliver better capacity performance and stability than pure PPy, because of the greatly improved conductivity of PPy accelerating the electrons transfer.…”

“…The initial capacity and capacity retention of the PPy‐based materials used for the cathode of Li–S batteries. [ 45–47,82–124 ] …”

Yolk–shell smart polymer microgels and their hybrids: fundamentals and applications

“…Because of the mentioned fascinating features, yolk-shell hybrid microgels have been extensively used in various elds such as drug delivery, 30 selective catalysis, 17,31 nanoreactors, 22 antibacterial activities, 32 adsorption of metal ions, 26 and lithium-sulfur batteries. 33 Because of the unique and unexplored properties of yolkshell microgels, different approaches including distillation precipitation polymerization, free radical polymerization, reux polymerization, etching of a silver layer, and removal of an intermediate polymeric core have been adopted for their preparation.…”