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[Display omitted] • Ti 3 C 2 T x /g-C 3 N 4 flexible free-standing electrode was prepared and show excellent performance. • Flexible solid-state supercapacitors were assembled and can work stably even in the 180° bending state. • DFT calculation was performed to reveal the mechanism of enhanced electrochemical performance of Ti 3 C 2 T x /g-C 3 N 4 heterostructure. With the popularity of intelligent portable electronic devices, bendable and flexible electronic equipment, such as portable miniature devices, wearable electronics, smart clothing, electronics, display, skin flexible smartphones and implantable medical devices have become a development trend. As potential energy storage device, flexible supercapacitors have attracted extensive attention. Ti 3 C 2 T x MXenes, which has high capacitance, mechanical strength and flexibility, perfectly meets the requirements of flexible energy storage devices. In order to avoid stacking, increase layer spacing, and enhance charge transfer efficiency, the Ti 3 C 2 T x /g-C 3 N 4 heterostructure is constructed by self-assembly method. The flexible self-supporting electrode is prepared by vacuum assisted filtration, which successfully widen the potential window and significantly improve the capacitance performance. The specific capacitance of the electrode in 1 M H 2 SO 4 electrolyte reaches 414 F/g at 1A/g. The electrode can simultaneously act as a fluid collector to construct a simple ultra-thin device. The flexible all-solid symmetric supercapacitor is assembled and the energy density reaches 23.98 Wh/Kg when the power density is 139.66 W/Kg. Encouragingly, the device can maintain stable performance under 180° bending conditions. The above excellent performance confirms the applicability of supercapacitors based on Ti 3 C 2 T x /g-C 3 N 4 heterostructure films for future portable, flexible or wearable electronic energy storage devices. [ABSTRACT FROM AUTHOR]

A high-performance flexible Zn-ion hybrid supercapacitor was fabricated by an adjustable structural optimization, and the potential practical value of the flexible all-solid-state hybrid supercapacitor was demonstrated. [Display omitted] • A zinc-ion hybrid supercapacitor derived from biomass carbon is fabricated. • The supercapacitor exhibits desirable flexibility and long cycling stability. • The remarkable performance is related to structural design. • A typical FZHSC device shows the potential practical application. The demand for developing sustainable energy storage renders biomass-based electrode materials a timely and important goal. However, the desirable electrochemical performance of the supercapacitor has still been hindered by insufficient contact chance between the active material and the electrolyte when both energy density and power density are required. Herein, the porous bamboo carbons were managed and used as the cathode to construct a flexible and high-performance Zn-ion hybrid supercapacitor (ZHSC) by combining the merit of capacitor-type and battery-type electrode materials. The porous material with high porosity is obtained via a controllable structural optimization. Consequently, the as-constructed hybrid supercapacitor delivers a superior specific capacitance of 321.3F g−1 at 1 A g−1 together with a high energy density of 114.2 Wh kg−1 when the power density is 800.0 W kg−1. Meanwhile, the assembled flexible hybrid supercapacitor displays remarkable cycling stability with 78% capacitance retention after 20,000 cycles and enough to suffer various deformations with no noticeable degradation of capacitance. Finally, the potential practical value of the flexible hybrid supercapacitor is demonstrated by an eye-catching orbital diagram. This work reveals that the flexible supercapacitor mainly constructed by porous biomass carbon is a promising candidate for energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The highlights of this work are as follows: • N-doped biochar derived from squid ink is premiere application for electrospinning. • Biochar composite with high-capacity used in flexible asymmetric supercapacitor. • The regulation of temperature and KOH content reveal the energy storage mechanism. Flexible supercapacitors have become a concern of flexible energy storage devices. In the process of exploring, the squid ink as N-doped biomass carbon was introduced to self-supporting flexible supercapacitors by electrospinning for the first time. By regulating the content of squid ink, the activation temperature, and the mass ratio of KOH-assisted activation, a N-doped porous biomass carbon@polyacrylonitrile (NPBC-1.5@PAN-800-2) with an ideal capacity and an excellent specific surface area (636.68 m2 g−1) was prepared. In addition, ZnO further optimized the capacity (422.7 F/g at 1 A g−1) and as an adhesive-free electrode for flexible asymmetric supercapacitor provided a relatively high specific capacitance, a satisfactory capacitance retention, and a wonderful energy density (48.01 Wh kg−1 at 1124.43 W kg−1). The capacitance was thought to originate from a suitable microporous structure, N-doped, and metal-derived pseudocapacitance propertie. [ABSTRACT FROM AUTHOR]