A strategy to prepare activated carbon fiber membranes for flexible solid-state supercapacitor applications

Abstract

The development of flexible supercapacitors is highly desired for electrode materials with good flexibility and a high specific surface area. The electrospun carbon fiber membranes (CFMs) have the possibility of being used as flexible electrodes due to their one-dimensional fiber structure. The pristine CFMs generally have poor porosity, and the activation process is of the essence. However, the conventional blending activation process will produce an uneven pore distribution and destroy the fiber membrane structure, which is not conducive to maintaining the flexibility of CFMs and hindering the application in flexible supercapacitors. Herein, by treating the electrospun CFMs with KOH impregnation activation process, we have succeeded in making the activation of CFMs more uniform and avoiding the occurrence of local over-activation. On the premise of ensuring that the fiber structure of CFMs is not damaged, the specific surface area of activated CFMs (ACFMs) was increased to 2408 m 2 g -1 , and the mechanical flexibility of CFMs was well maintained. As a result, the optimal ACFMs delivers a specific capacitance of 289.2 F g -1 at a current density of 0.5 A g -1 in aqueous electrolyte and an energy density of 14.8 Wh kg -1 in neutral electrolyte. In addition, the flexible solid-state symmetric supercapacitor also shows excellent electrochemical performance, making it have great potential in energy storage applications for wearable, foldable, and portable electronic devices.

Surface Redox Pseudocapacitance Boosting Vanadium Nitride for High‐Power and Ultra‐Stable Potassium‐Ion Capacitors

“…The PICs of VN@CFs||ACFs were assembled with the VN@CFs‐550 as the anode and the activated carbon fiber membrane (ACFs) as the cathode. [ 52 ] Upon the charging process, K + and FSI – are separately electrochemically adsorbed into the VN@CFs and the ACFs ( Figure a). Before constructing the PICs, the ACFs was tested as the cathode with metallic potassium as the counter electrode.…”

“…The ACFs cathode was prepared according to previous literature. [58] The VN@CFs||ACFs PICs were assembled by the similar method of half-cells with the pre-activated VN@CFs and ACFs. The specific energy density (E, Wh kg -1 ) and power density (P, W kg -1 ) were calculated according to the GCD profiles using the following equations:…”

“…The ACFs cathode was prepared according to previous literature. [ 58 ] The VN@CFs||ACFs PICs were assembled by the similar method of half‐cells with the pre‐activated VN@CFs and ACFs. The specific energy density ( E , Wh kg –1 ) and power density ( P , W kg –1 ) were calculated according to the GCD profiles using the following equations: $$\[ \begin{array}{*{20}{c}}{E = \mathop \smallint \limits_{{t_1}}^{{t_2}} \frac{{U\; \times \;I}}{m}dt\;\;\;\;\;\;\;\;\;P = \frac{E}{t}\; \times \;3600}\end{array} \]$$in which I (A) is the discharge current, U (V) is the working voltage excluding the IR drop, m is the total mass of active materials, t 1 (s) and t 2 (s) are the start and end times of the PIC discharge, respectively, and t (s) is the value of t 1 –t 2 .…”

Hollow MoS2 Spheres Confined in Carbon Fibers for Ultralong-life Potassium Storage

“…Thereinto, ACFMs were obtained by activating pristine CNFs according to our previous work (Figure S12). The ACFM electrode possesses an ultra-high specific surface area of 2408 m 2 g –1 and a luxuriant mesoporous structure, which is conducive to the adsorption of FSI – . The electrochemical characteristics of the ACFM cathode are shown in Figure S13.…”

Porous Carbon Nanofibers with Heteroatoms Doped by Electrospinning Exhibit Excellent Acetone and Carbon Dioxide Adsorption Performance: The Contributions of Pore Structure and Functional Groups

“…KOH usually reacts with carbon materials during the activation. − The KOH and C redox reaction occurs and the carbon framework is etched; potassium ions are inserted above 700 °C. , Finally, 5% hydrochloric acid is used to wash away the impurities on the surface of U 1 K 2 -X.…”