High-Performance Flexible Asymmetric Fiber-Shaped Supercapacitor Based on CF/PPy and CNT/MnO₂ Composite Electrodes

Abstract

Fiber-shaped supercapacitors (FSSs) are identified as promising facilities in flexible and wearable energy storage fields. In this study, an electrode with excellent formability was accomplished by depositing polypyrrole on highly aligned discontinuous carbon fiber (CF/PPy). For the FSS with core− sheath structure, CF/PPy fiber was the core electrode, LiCl/PVA was the electrolyte, and carbon nanotube/MnO 2 (CNT/MnO 2 ) film was the opposite electrode. The charge of core and opposite electrodes was paired by adjusting the electrochemical reaction times of MnO 2 and PPy. The obtained FSS had an areal capacitance of 66.27 mF cm −2 (lineal capacitance of 13.52 mF cm −1 and volumetric capacitance of 4.08 F cm −3 ) and a broadened potential window of 1.6 V, which resulted in a maximum energy density of 23.56 μWh cm −2 . The cycling stability was evaluated by charge−discharge test, and it retained 83% of its initial capacitance after 5000 cycles. Furthermore, the FSS showed exceptional flexibility and it retained above 90% of its capacitance after 200 repeated bending tests, illustrating excellent mechanical stability.

Cauliflower-Like Ni/MXene-Bridged Fiber-Shaped Electrode for Flexible Microsupercapacitor

“…Figure d displays the Ragone plot of the asymmetric FSC device, indicating that energy density varies from 206 to 172 μWhcm –2 at a power density range of 1.94–9.29 mW cm –2 . As shown in the Ragone plot, this result is obviously better than that of previously reported FSCs. ,,,,− The flexibility of the device was further investigated by CV measurements under 0°, 45°, 90°, and 135° bending states at 50 mVs –1 . As can be exhibited in Figure e, the electrochemical behavior of the FSC device is almost the same in all conditions, implying excellent flexibility of the fabricated FSC.…”

“…With growing demands for lightweight, wearable, and miniaturized energy storage systems, flexible wire or fiber-shaped supercapacitors (FSCs) have drawn more attention. − There are diverse types of FSC substrate materials like carbon fibers, polymer fibers, and metal wires. − Among metals, Cu wire is an encouraging electrode platform due to its unique benefits like high electrical conductivity, mechanical strength, flexibility, and being rather lightweight with low cost. However, the low surface area and contact conductance of the metal wires to semiconductor active materials lead to their limited areal and volumetric energy densities as being crucial factors for portable electronics. ,, …”

Flexible and Conductive Polymer Threads for Efficient Fiber-Shaped Supercapacitors via Vapor Copolymerization

“…Based on the GCD curve, the linear specific capacitance of the whole device was calculated to be 79.3 mF cm –1 at a current density of 0.1 mA cm –1 , with the corresponding areal specific capacitance and volumetric capacitance of 192.3 mF cm –2 and 12.0 F cm –3 , respectively. The specific capacitance is higher than that of many fiber supercapacitors reported in the literature. − To represent the relationship between energy density and power density, the Ragone plot was obtained from GCD curves and compared with other reported representative works (Figure f). The as-prepared FSSC delivered the highest energy density of 13.8 μWh cm –2 (linear energy density of 5.6 μWh cm –1 and volumetric energy density of 0.85 mWh cm –3 ) and a power density of 87.4 μW cm –2 (linear power density of 35.7 μW cm –1 and volumetric power density of 5.4 mW cm –3 ) at a current density of 0.1 mA cm –1 .…”

Facile hydrothermal synthesis of cobaltosic sulfide nanorods for high performance supercapacitors

“…Therefore, calculations based on the GCD curves can be performed to obtain a maximum volumetric energy density of 0.87 mW h cm −3 and a power density of 0.89 W cm −3 ( Fig. 4f ), which is superior to other recently reported devices, such as NiCoS/NF//r-GO-based ASCs (2.04 mW h cm −3 and 42.64 mW cm −3 ), 39 L-VN@AC//α-MnO 2 -based ASCs (8.5 mW h cm −3 and 34.3 mW cm −3 ), 40 CF/PPY//CNT/MnO 2 -based ASCs (0.27 mW h cm −3 and 24.1 mW cm −3 ), 41 CFF@V 2 O 5 //CFF@AC-based ASCs (0.928 mW h cm −3 and 17.5 mW cm −3 ), 42 MnO 2 /ZnO//rGO-based ASCs (0.234 mW h cm −3 and 133 mW cm −3 ), 43 CPCC@CuO@Mn(OH) 2 //CC@AC-based ASCs (0.18 mW h cm −3 and 18 mW cm −3 ). 44 All the results prove the high performance and practicality of the synthesized electrodes.…”