A high-voltage quasi-solid-state flexible supercapacitor with a wide operational temperature range based on a low-cost "water-in-salt" hydrogel electrolyte. Issue 5 (28th January 2021)

• Record Type: Journal Article
• Authors: Deng, Yongqi; Wang, Hongfei; Zhang, Kefu; Shao, Jingwen; Qiu, Jun; Wu, Juan; Wu, Yihan; Yan, Lifeng
• Is Part Of: Nanoscale. Volume 13:Issue 5(2021)
• Page Start: 3010
• Page End: 3018
• Publication Date: 2021-01-28
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d0nr08437a
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Low-cost and quasi-solid-state polyelectrolyte hydrogel accommodating a superhigh concentration of CH3 COOK has been prepared for supercapacitors with high ionic conductivity and electrochemical window. Abstract : Recently, "water-in-salt" electrolytes have provided a huge boost to the realization of high energy density for water-based supercapacitors by broadening the electrochemical stability window. However, the high cost and low conductivity of high concentration LiTFSI greatly restrict the possibility of practical application. Herein, we adopt a new strategy to develop a low-cost and quasi-solid-state polyelectrolyte hydrogel accommodating a superhigh concentration of CH3 COOK through in situ polymerization, avoiding the problem that many conventional polymers cannot accommodate ultra-high ion concentration. The polyelectrolyte hydrogel with 24 M CH3 COOK exhibits a conductivity of up to 35.8 mS cm −1 and a stretchability of 950%. With advanced N-doped graphene hydrogel electrodes, the assembled supercapacitor yields a voltage window of 2.1 V with an energy density of 33.0 W h kg −1 and superior cyclability with 88.2% capacitance retention at 4 A g −1 after 6000 cycles comparable to those supercapacitors using high-cost LiTFSI salts. Besides, the supercapacitor with excellent temperature stability in the range of −20 to 70 °C can light an LED for more than one minute. The assembled flexible device with the PAAK/CMC-24 M gel film sandwiched in between demonstrates excellent bendability from 0° to 180° and shows great potential for flexible/wearable electronic devices. Our feasible approach provides a new route for assembling quasi-solid-state flexible high-energy storage devices with "water-in-salt" electrolytes.