Low-Cost Biomass-Gel-Induced Conductive Polymer Networks for High-Efficiency Polysulfide Immobilization and Catalytic Conversion in Li–S Batteries

Abstract

Lithium−sulfur batteries are regarded as one of the most promising candidates for next-generation energy storage systems because of their high energy density and the low cost of sulfur. However, practical applications are still impeded by sluggish redox kinetics and the shuttling effect of soluble intermediate lithium polysulfides (LiPSs), which induces irreversible loss of active materials, self-discharge, and thus poor cycle stability. Herein, a polysulfide-anchored catalytic polymer is reported to solve the shuttling behavior and improve battery performance. Natural polymer xanthan gum and konjac gum with abundant polar oxygen-containing functional groups (−OH, CO, −COOH, and −O−) that induce strong binding interactions with lithium polysulfide and reduce the energy barrier of the reaction from S 8 to Li 2 S are entangled with a conductive carbon nanotube (CNT) skeleton as a polysulfide shielding interlayer. Combined with the highly conductive CNT porous network that facilitates Li + ion transportation, the CNT−biomass gel interlayer is endowed with great capability of adsorbing and catalyzing the active sulfur. Benefiting from these synergistic attributes, the as-obtained CNT−biomass gel composite interlayer can achieve excellent performance of a high initial capacity of 998.2 mA h g −1 at 0.2C and a slight capacity decay of 0.078% per cycle at 0.5C over 200 cycles. More importantly, the battery demonstrates a cycle stability at a high sulfur loading of 3.0 mg cm −2 . The proposed strategy will contribute to the design of biomass-derived materials for Li−S batteries. Natural polymer xanthan gum and konjac gum with abundant polar oxygen-containing functional groups that induce strong binding interactions with lithium polysulfide and reduce the energy barrier of the reaction from S 8 to Li 2 S are entangled with a conductive carbon nanotube skeleton as a polysulfide shielding interlayer. The CNT−biomass gel interlayer is endowed with a great capability of adsorbing and catalyzing the active sulfur.

Flexible and Conductive Membrane with Ultrahigh Porosity and Polysulfide-Conversion Catalytic Activity for Large-Scale Preparation of Li–S Batteries

“…The F 1s spectrum in Figure c reveals the chemical instances of the F atom after cycling. The F 1s spectrum shows one peak located at 687.9 eV which can be attributed to the −CF 2 of PVDF, and the three peaks at 685.6, 688.0, and 689.26 eV can be indexed to the Li–F bond (LiFSI), −CF 2 (PVDF), and −CF 3 (electrolyte), which confirms the strong anchoring effect of the PVDF polymer to LiPSs. , The Li 1s spectrum in Figure d exhibits three peaks at 55.7, 56.2, and 56.7 eV, which were attributed to the Li–F (LiFSI from the electrolyte), Li–O, and Li–S bonds, respectively, further revealing the adsorption interaction between the Fe 2 O 3 -CNT@PVDF interlayer and the LiPSs. , To further evaluate the anchoring ability of the Fe 2 O 3 -CNT@PVDF flexible interlayer, DFT was used to theoretically investigate the adsorption energy to LiPSs on various interfaces. Figure e depicts the adsorption energy curve of the three functional additives to the active substance.…”

Emerging Strategies for Gel Polymer Electrolytes with Improved Dual‐Electrode Side Regulation Mechanisms for Lithium‐Sulfur Batteries

“…The hydroxyl (À OH) functional group in the starch can chemically bond with the polysulfide to effectively reduce the shuttle effect (Figure 5b). As a result, the reversible specific capacity of the cell with this GPE is as high as 667.4 mAh g À 1 after 500 cycles at 0.5 C. Jiang et al [58] using natural polymers xanthan gum and konjac gum as polymer matrices, and subsequently prepared carbon nanotube biomass gel foams (CNT biomass gels) by hydrogen bonding wrapped around the surface of carbon nanotubes and used in LiÀ S batteries. And the abundant polar oxygen-containing functional groups (À OH, À CO and À COOH, etc.)…”

Renewable biomass-derived carbon-based hosts for lithium–sulfur batteries

“…The RPC as a modication material is devoted to enhancing the electrical conductivity and wettability between the separator To improve the attractiveness of polysuldes, many studies have designed polar-acting carbon as a separator material. Jiang et al 282 incorporated carbon nanotubes (CNTs) into biomass gel foams derived from the xanthan gum and konjac gum composite gel system and coated them on battery separators as interlayers by both adsorption and catalysis (Fig. 19b and c).…”