Fibrous Materials for Flexible Li–S Battery

Abstract

density and good flexibility. [6][7][8][9][10] Among various battery technologies, lithiumsulfur (Li-S) batteries have received considerable attention due to their ultrahigh theoretical energy density (2567 Wh kg −1 ), environmental benignancy, and low cost of S. [11][12][13] However, their applications in the wearable electronics are hampered by the severe interfacial issues, e.g., the formation of Li dendrites and the shuttle effect of polysulfide, which occur in the Li-S chemistries. [14][15][16][17][18] In addition, most Li-S batteries exhibit poor mechanical stability and low areal capacity. [11,12,18] During the past decades, there is an increasing interest in the development of cutting-edge materials that can simultaneously endow Li-S batteries with high energy, long cycle life, and good flexibility. [11,18,19] Among those, fibrous materials represent a promising option attributing to their large surface area (10 2-3 m 2 kg −1 ), lightweight, good flexibility, and cost-effectiveness. Generally, fibrous materials are in the form of high-aspect-ratio (>50) fibers, filaments, yarns, and their superstructures with the geometrical sizes from several hundreds of nanometer to meter. [20] Material wise, they consist of metals, carbons, ceramics, polymers, and composites of those. [21][22][23][24][25] The fibrous materials provide a solid, hollow, coreshell, or hierarchically porous structure. [26][27][28][29][30] Mechanically, most of the fibrous materials are flexible and even stretchable, which can sustain complex deformations. [31][32][33] Technically, fibrous materials and their assemblies are highly manufacturable via various high-throughput methods such as spinning, vacuum infiltration, and textile technology. [34][35][36] With these appealing properties, fibrous materials have been demonstrated to serve as different battery components of Li-S batteries (Figure 1), including current collectors of both Li anodes and S cathodes, buffer layers, interlayers, and solid-state electrolytes (SSEs).Considering the great promises of utilizing fibrous materials in Li-S batteries, this review presents the recent advances of this rapidly developing area. We first introduce the working principles and the challenges of Li-S batteries (Section 2). We then give an overview of the advantages of using fibrous materials for flexible Li-S batteries (Section 3). After that, we provide an in-depth discussion on the preparation of fibrous materials and the design of fibrous structures and functionalities for flexible current collectors (Section 4) and flexible interfacial layers (Section 5) of Li-S batteries, with a special focus on the enhancements of electrochemical and mechanical performances of Li anodes and S cathodes. Regarding the device-level performance, we finally highlight several layouts of flexible Li-S batteries including wire-type battery, battery with integrated architecture, and foldable battery (Section 6).The lithium-sulfur (Li-S) battery is an attractive high-energy-density technology for future flexible and wea...

Design Principles and Applications of Next‐Generation High‐Energy‐Density Batteries Based on Liquid Metals

“…[72,73] Flexible batteries have been reported to be achieved with flexible structural designs or deformable conductive polymers. [74][75][76][77][78] Due to the superior fluidity and flexibility, liquid metals could also be promising electrode selections for flexible batteries. Figure 5c indicates a reported flexible battery with the wire-shaped encapsulation of the EGaIn as the anode material in a metal-air battery to maintain the electrical contact during deformation.…”

Textile Composite Electrodes for Flexible Batteries and Supercapacitors: Opportunities and Challenges

“…Therefore, one key future development for TCEs would be the improvement of their energy density, thereby allowing them to consistently power various flexible and wearable electronics such as smart watches, foldable phones, and bendable displays. [33] One possible development avenue is to reduce the inert components of the cells, both in weight and volume, by developing much thinner and lighter building blocks (e.g., thinner fibers or bundles) of the textile current collectors and by increasing the packing density of the active materials. Alternatively, high capacity/capacitance fibrous materials could be developed and then assembled into flexible fibrous electrodes with high packing density.…”

“…MFEs are inflexible owing to the intrinsically low yield strains of metal foils. [33,34] Metal foils crack and fracture after being repeatedly bent to a small radius of curvature, and flexing the MFEs may lead to swelling or the delamination of the active layers from the metals (Figure 1g). [35][36][37] In contrast, TCEs show excellent flexibility owing to their combination of flexible materials and flexible structures, as discussed below (Figure 1h).…”

A non‐Newtonian fluidic cellulose‐modified glass microfiber separator for flexible lithium‐ion batteries

“…Due to the increasing demand for portable communication devices, 1,2 flexible electronic equipment, 3–6 and electric vehicles, 7–9 there is an urgent need to develop flexible rechargeable energy storage and conversion devices such as supercapacitors, 10–12 lithium‐ion batteries (LIBs), 13–15 metal‐air batteries, and so on 16–18 . The separator is a part of these electrochemical energy devices that ensures ion transmission and maintains electrode stability and device safety 19–21 …”