A simple route to fiber-shaped heterojunctioned nanocomposites for knittable high-performance supercapacitors

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 23; pp. 11589 - 11597
• Main Authors: Zhang, Xin, Chen, Xing, Bai, Tian, Chai, Jiaqi, Zhao, Xin, Ye, Meidan, Lin, Zhiqun, Liu, Xiangyang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 16.06.2020
• Subjects: Charge transport; electrochemical capacitors; Electrodes; Electronics; electroplating; energy density; fabrics; Flux density; Light emitting diodes; Nanocomposites; Nanosheets; Nanotechnology; Nanowires; nitrides; Performance enhancement; Stainless steel; Stainless steels; Sulfides; Supercapacitors; Ultrafines; Wearable technology; Weight reduction
• ISSN: 2050-7488; 2050-7496; 2050-7496
• DOI: 10.1039/d0ta04150e

Fiber-shaped supercapacitors with high energy density have been an active subject of research due to their promising prospect for use in portable and wearable electronics. Herein, we report on a robust two-step strategy for crafting a MgS nanowire-draped NiCo 2 S 4 nanosheet network ( i.e. , NiCo 2 S 4 @MgS nanocomposites) in situ grown on ultrafine flexible stainless steel microwires to render knittable supercapacitors with markedly enhanced performance. The two-step route involves the formation of oxide compounds, followed by their conversion into NiCo 2 S 4 @MgS nanocomposites. In sharp contrast to pure NiCo 2 S 4 nanosheets, NiCo 2 S 4 @MgS nanocomposites facilitate a rapid charge transport between NiCo 2 S 4 nanosheets and MgS nanowires due to the presence of the interconnected MgS network and manifest a more than two-fold discharging time over that of NiCo 2 S 4 . Notably, fiber-shaped asymmetric supercapacitors (denoted as FASCs), assembled by intertwining a NiCo 2 S 4 @MgS positive electrode and a FeOOH negative electrode electrodeposited on the same type of stainless steel microwires, deliver a remarkable specific volumetric capacity of 134.4 mA h cm −3 , a high energy density of 107.5 mW h cm −3 , and a good power density of 1.7 W cm −3 at 1 mA cm −2 . More importantly, the FASCs also demonstrate great stability with 87.5% performance retention after 5000 cycles. Such hair-like FASCs enable the successful charging of an electronic bracelet, and can power light-emitting diodes (LEDs) after being woven into fabrics. As such, the two-step strategy in this study may represent a viable means of yielding a variety of metal-containing oxide, sulfide, and nitride networks on stainless steel microhairs for high-performance and light-weight wearable electronics. Fiber-shaped asymmetric supercapacitors composed of heterojunctioned NiCo 2 S 4 @MgS nanocomposites were demonstrated and can be conveniently knitted into fabrics for wearable electronics.