High‐Performance Yarn Supercapacitor Based on Metal–Inorganic–Organic Hybrid Electrode for Wearable Electronics

Abstract

A flexible all‐solid‐state yarn supercapacitor (YSC) based on metal–inorganic–organic ternary hybrid structure is fabricated by assembling polypyrrole@manganese oxide nanosheets@stainless steel yarn (PMS) yarn electrode of core/sheath/sheath configuration. The PMS yarn electrode combines the advantages of each component and shows excellent electrochemical performance, mechanical flexibility, and flame retardance owing to its unique structure and synergistic effect. The as‐fabricated YSC exhibits a high areal specific capacitance of 181 mF cm−2, areal energy density of 16.1 µWh cm−2, and areal power density of 10.3 mW cm−2. Moreover, the device possesses desirable voltage/current scalability and outstanding mechanical stability, which maintains 95.8% capacitance retention after 1000 bending cycles. As a demonstration, four YSCs are connected in series and then charged for 10 s to drive a light‐emitting diode (LED) digital watch. The outstanding overall performance of the YSC indicates that it is an ideal flexible power source for safe wearable electronics.

Flexible Polypyrrole@Fe2O3@Stainless Steel Yarn Composite Electrode for Symmetric Thread‐Like Supercapacitor with Extended Operating Voltage Window in Li2SO4‐Based Aqueous Electrolyte

“…The Ragone plot of the device is displayed in Figure 6e. The highest areal energy density of the device (E A, device ) reaches 39.3 μWh cm −2 when the areal power density (P A, device ) is 1.34 mW cm −2 , and the maximum P A, device reaches 33.3 mW cm −2 with an E A, device of 16.0 μWh cm −2 , which are superior compared with previously reported aqueous symmetric TSCs based on PPy/manganese oxide/SSY (16.06 μWh cm −2 and 10.33 mW cm −2 ), [5] poly(3,4-ethylenedioxythiophene) (PEDOT) fiber (19.6 μWh cm −2 and 1.875 mW cm −2 ), [43] reduced graphene oxide-PEDOT:poly(styrene sulfonate) fiber (4.55 μWh cm −2 and 0.125 mW cm −2 ), [44] PPy/bacterial cellulose/cotton yarn (16.9 μWh cm −2 and 0.17 mW cm −2 ), [45] PEDOT-ruthenium oxide@PEDOT fiber (22.5 μWh cm −2 and 0.75 mW cm −2 ). [46] As shown in Figure 6f, the device keeps 80.9% of its initial capacitance after 10 000 cycles at 32 mA cm −2 , and the Columbic efficiency is above 98.5% during the 10 000 cycles.…”

“…[4] Among them, SSY produced by twisting lots of slender stainless steel monofilaments possesses superior mechanical flexibility and strength, which is an ideal candidate as linear support for TSCs. [5,15,16] TSCs have a serious shortcoming of low energy density like other SCs, which hinder the applications in practice. For SCs, the energy density (E) can be increased by enhancing either the specific capacitance (C) or the operating voltage window (U) based on the energy density equation ( 1 22 E CU =…”

“…[ 1,2 ] Particularly, TSCs have attracted great attention because they not only retain the advantages of supercapacitors (SCs) including high cyclic stability, high power density and environmental friendliness, but also exhibit extraordinary knittability and weavability, which are very promising power source for wearable electronics. [ 3–5 ] Generally speaking, the electrodes of TSCs are built on the linear supports such as carbonaceous fibers/yarns (e.g., carbon fibers, carbon nanotube yarns and graphene fibers), [ 6–8 ] metal wires/yarns (e.g., stainless steel yarns (SSY), Au wires and Cu wires) [ 9–11 ] and textile yarns (e.g., cotton yarns, polyester yarns and nylon yarns), [ 12–14 ] and then various active materials are coated on the surface of the linear supports to provide/improve capacitance. Among these supports, linear metal materials are of great interest due to their ultrahigh electrical conductivity, allowing them function as current collectors at the same time.…”

“…[ 4 ] Among them, SSY produced by twisting lots of slender stainless steel monofilaments possesses superior mechanical flexibility and strength, which is an ideal candidate as linear support for TSCs. [ 5,15,16 ]…”

Compressible All‐In‐One Supercapacitor with Adjustable Output Voltage Based on Polypyrrole‐Coated Melamine Foam

“…[9][10][11][12] Recently, substantial effort has been devoted to endow flexible supercapacitors with more efficiency, more stability, and low cost in order to develop fully flexible electronics. [16][17][18][19] Compared with the common flexible supercapacitors with laminated structure, the major components of the all-inone flexible supercapacitors including two electrodes, separator, electrolyte, and current collectors are integrated on the same substrate. Generally, the common flexible supercapacitors exhibit a multilayer laminated configuration, which are fabricated by placing a gel electrolyte layer between two flexible electrodes.…”