Flexible conductive carbon/metal composite nanofiber membrane, preparation method and application thereof, and lithium-sulfur battery

Abstract

The invention provides a flexible conductive carbon / metal composite nanofiber membrane, a preparation method and application thereof, and a lithium-sulfur battery, and belongs to the field of lithium-sulfur batteries. According to the invention, a conductive nanofiber membrane reactor is reasonably designed, chemical adsorption, electro-catalysis and ion (Li+) diffusion of a lithium-sulfur batterymembrane reactor are combined, polysulfide is limited on a nanoscale surface, and reversible conversion kinetics of the polysulfide is accelerated, so that the high sulfur utilization rate is realized, and in a rapid rechargeable, high-energy and high-power future lithium-sulfur battery technology, the flexible conductive carbon / metal composite nanofiber membrane has good rate capability and capacity retention capability under high discharge / charge current density, so that the lithium-sulfur battery is promoted to be developed towards the directions of high capacity and long cycle service life.

Description

technical field [0001] The invention relates to the technical field of lithium-sulfur batteries, in particular to a flexible conductive carbon / metal composite nanofiber membrane, a preparation method and application thereof, and a lithium-sulfur battery. Background technique [0002] Conversion chemistry is the main electronic and energy storage process of lithium / sulfur (Li / S) batteries, involving the conversion of solid-state sulfur (S 8 ) to soluble lithium polysulfide (LiPS, Li 2 S x ,x:4~8) to solid Li 2 Multistep chemical transformations and phase transitions of S. S 8 to Li 2 S 8 The transformation of Li is a spontaneous process from a thermodynamic point of view, and polysulfides are essential to maintain the high capacity of lithium-sulfur batteries, from long-chain Li 2 S 8 to the short chain Li 2 Two-electron / lithium-ion redox conversion reaction during stepwise sulfur (S-S) bond scission of S (2Li + +2e - +xS→Li 2 S x (1≤x≤8)). Li 2 S x The bindin...

AI Technical Summary

Problems solved by technology

However, severe shuttling of polysulfides, slow reaction kinetics, and poor electron / Li+ transport during discharge / charge cycling at high current densities lead to low effective sulfur utilization , leading to a sharp decline in capacity and a short cycle life, it is difficult to achieve the theoretical capacity (1675mAh·g-1) and energy density (2600Wh·kg-1) requirements

[0003] Confinement of polysulfides while accelerating the redox conversion kinetics of polysulfides by designing materials with high electrical conductivity and catalytic activity as sulfur supports was recently developed strategy, which anchors polysulfides through strong chemical adsorption, inhibits the shuttling of polysulfides, and reduces the activation energy of the reaction through electrocatalysis to accelerate the redox reaction kinetics; with the rapid development of sulfur carrier improvement and diaphragm improvement In contrast, the interlayer provides another convenient method and battery assembly for the new construction of lithium / sulfur batteries to solve the problem of slow species conversion of polysulfides under high current density and high sulfur loading conditions. The problems and challenges faced by the electrochemical kinetics in the / S battery, such as the use of microporous carbon paper, porous carbon film and electron transport carbon film as the intermediate layer, etc., but found in the study that the unit loading of the sulfur electrode determines the lithium The overall capacity of the sulfur battery, the traditional high-sulfur-loaded electrode sheet has the problem of poor ion conduction, electronic conductivity and electrolyte wettability during the cycle of the battery, and low sulfur utilization.

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