High-Performance Nanostructured Supercapacitors on a Sponge

Abstract

A simple and scalable method has been developed to fabricate nanostructured MnO2-carbon nanotube (CNT)-sponge hybrid electrodes. A novel supercapacitor, henceforth referred to as "sponge supercapacitor", has been fabricated using these hybrid electrodes with remarkable performance. A specific capacitance of 1,230 F/g (based on the mass of MnO2) can be reached. Capacitors based on CNT-sponge substrates (without MnO2) can be operated even under a high scan rate of 200 V/s, and they exhibit outstanding cycle performance with only 2% degradation after 100,000 cycles under a scan rate of 10 V/s. The MnO2-CNT-sponge supercapacitors show only 4% of degradation after 10,000 cycles at a charge-discharge specific current of 5 A/g. The specific power and energy of the MnO2-CNT-sponge supercapacitors are high with values of 63 kW/kg and 31 Wh/kg, respectively. The attractive performances exhibited by these sponge supercapacitors make them potentially promising candidates for future energy storage systems.

Ultrahigh‐Power Pseudocapacitors Based on Ordered Porous Heterostructures of Electron‐Correlated Oxides

“…In this regard, controlling nanostructures and exploring novel materials have become critical processes to meet these requirements in developing TMO‐based composite electrodes,1, 6, 17, 23, 25 wherein various conductive materials, including nanostructured carbons (such as porous carbon,14, 26 carbon nanotubes,27, 28, 29, 30 and graphene 31, 32) and conducting polymers, are extensively employed to serve as electron pathways. Although the large specific surface area in these low‐dimensional composite nanostructures allows ion transports,1, 17, 23, 26, 27, 28, 29, 30, 31, 32 their assembled bulk electrodes usually exhibit high electrical resistance as a result of the short electron transport distance within these low‐dimensional conductive materials, the undesirably high contact resistances produced by the coating of electrically insulating active TMOs and polymer binders, as well as the weak and noncoherent TMO/conductor interfaces 24, 33, 34, 35. This inevitably leads to unsatisfactory improvements in rate capability, volumetric energy and power densities of pseudocapacitors 1, 17, 23.…”

Engineering three-dimensional hybrid supercapacitors and microsupercapacitors for high-performance integrated energy storage

“…Nevertheless, the thickness and the area-normalized capacitance of these electrodes are not adequate for most applications. A promising approach to realize practical applications of MnO 2 is to incorporate nanostructured MnO 2 on highly conductive support materials with high surface areas such as nickel nanocones (13), Mn nanotubes (14), activated carbon (15), carbon fabric (16), conducting polymers (17), carbon nanotubes (18,19), and graphene (20)(21)(22)(23)(24). Although promising…”

Flexible Supercapacitors – Development of Bendable Carbon Architectures

“…In addition to the textile composite, this group also used sponges as support substrates to fabricate nanostructured MnO 2 /CNT/sponge hybrid electrodes. [138] The SCs based on these hybrid electrodes exhibited high specific power and energy densities of 63 kW/kg and 31 Wh/kg, respectively. The MnO 2 /CNT/sponge SCs show only 4% of degradation after 10000 cycles at a charge-discharge specific current of 5 A/g.…”

“…Both the specific capacitances and rate capabilities depend on the average size of the MnOx nanoparticles on the CNTs, as indicated in CV and charge/discharge curves (Figure 10c More recently, coating MO, and/or CNT composites on textiles, sponges, and papers have also been reported as feasible methods to prepare flexible electrodes for SCs. [11,[137][138][139] As mention in 3.1 section, highly conductive SWCNTs/cloth electrodes can be obtained by simple "dipping and drying" process using SWCNT ink. [11] To improve the energy density of the SWCNTs/cloth electrodes, MnO 2 was uniformly electrodeposited on the SWCNTs.…”