Solid-State Thin-Film Supercapacitors with Ultrafast Charge/Discharge Based on N-Doped-Carbon-Tubes/Au-Nanoparticles-Doped-MnO₂ Nanocomposites

Abstract

Although carbonaceous materials possess long cycle stability and high power density, their low-energy density greatly limits their applications. On the contrary, metal oxides are promising pseudocapacitive electrode materials for supercapacitors due to their high-energy density. Nevertheless, poor electrical conductivity of metal oxides constitutes a primary challenge that significantly limits their energy storage capacity. Here, an advanced integrated electrode for high-performance pseudocapacitors has been designed by growing N-doped-carbon-tubes/Au-nanoparticles-doped-MnO2 (NCTs/ANPDM) nanocomposite on carbon fabric. The excellent electrical conductivity and well-ordered tunnels of NCTs together with Au nanoparticles of the electrode cause low internal resistance, good ionic contact, and thus enhance redox reactions for high specific capacitance of pure MnO2 in aqueous electrolyte, even at high scan rates. A prototype solid-state thin-film symmetric supercapacitor (SSC) device based on NCTs/ANPDM exhibits large energy density (51 Wh/kg) and superior cycling performance (93% after 5000 cycles). In addition, the asymmetric supercapacitor (ASC) device assembled from NCTs/ANPDM and Fe2O3 nanorods demonstrates ultrafast charge/discharge (10 V/s), which is among the best reported for solid-state thin-film supercapacitors with both electrodes made of metal oxide electroactive materials. Moreover, its superior charge/discharge behavior is comparable to electrical double layer type supercapacitors. The ASC device also shows superior cycling performance (97% after 5000 cycles). The NCTs/ANPDM nanomaterial demonstrates great potential as a power source for energy storage devices.

Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High‐Potential Window Electrodes for High‐Performance Supercapacitors

“…The Mn 2p 3/2 peak of all samples can be deconvoluted into three peaks as Mn 4+ (642.8 eV), Mn 3+ (641.8 eV), and Mn 2+ (640.7 eV). [1,36,37] The proportion of Mn 4+ peaks shows almost no change after PECVD process, demonstrating the phase stability in the PECVD process. [38] Moreover, chemical titration was used to further quantitatively confirm the average valence for Mn in different samples.…”

“…Supercapacitors which pose faster charge/discharge rates and higher power density are becoming hot topics of current research worldwide. [1][2][3][4] However, the practical application of supercapacitors has long been a challenge because of their limited energy density. Thus, focused on the voltage undertaken by structural modification through Na + deintercalation and intercalation and found that the potential of the Mn 3 O 4 can be extended to 1.3 V through this method.…”

Nanostructured MnO2 as Electrode Materials for Energy Storage

“…Lv et al [185] demonstrated the superior cycling performance (97% after 5000 cycles) of the nanocomposite formed by N-doped carbon tubes and Au-doped MnO 2 nanoparticles. Fan et al [186] proposed a new composite of carbon nanotubes (CNTs)/graphene, composed of CNT pillars sandwiched between the graphene sheets that showed a specific capacitance as high as 385 F·g −1 .…”

Scalable Fabrication of Flexible Solid‐State Asymmetric Supercapacitors with a Wide Operation Voltage utilizing Printable Carbon Film Electrodes

“…What is more, the flexible ASC exhibits an energy density of 0.776 mWh cm −3 at a power density of 9.859 mW cm −3 for a 2.0 V voltage window, as shown in Figure e. It also preserves 52 % of its energy density as the power density increases to 142.56 mW cm −3 . These values are higher than the values reported for other solid‐state SCs such as N‐doped‐CNTs//Au‐doped‐MnO 2 ASC (0.097 mWh cm −3 ), MnO 2 //Fe 2 O 3 ASC (0.55 mWh cm −3 ), VO x //VN ASC (0.61 mWh cm −3 ), MnO 2 @ZnO//reduced graphene oxide (RGO) ASC (0.234 mWh cm −3 ), TiO 2 @C NWs symmetrical supercapacitor (SSC; 0.011 mWh cm −3 ), and NiCo 2 O 4 @TiN SSC (0.061 mWh cm −3 ) . These results indicate that the flexible solid‐state ASC holds promise for use in portable energy‐storage systems.…”