Carbon Nanotube Based Robust and Flexible Solid-State Supercapacitor

Abstract

All solid-state flexible electrochemical double-layer capacitors (EDLCs) are crucial for providing energy options in a variety of applications, ranging from wearable electronics to bendable micro/nanotechnology. Here, we report on the development of robust EDLCs using aligned multiwalled carbon nanotubes (MWCNTs) grown directly on thin metal foils embedded in a poly­(vinyl alcohol)/phosphoric acid (PVA/H3PO4) polymer gel. The thin metal substrate holding the aligned MWCNT assembly provides mechanical robustness and the PVA/H3PO4 polymer gel, functioning both as the electrolyte as well as the separator, provides sufficient structural flexibility, without any loss of charge storage capacity under flexed conditions. The performance stability of these devices was verified by testing them under straight and bent formations. A high value of the areal specific capacitance (C SP) of ∼14.5 mF cm–2 with an energy density of ∼1 μW h cm–2 can be obtained in these devices. These values are significantly higher (in some cases, orders of magnitude) than several graphene as well as single-walled nanotube-based EDLC’s utilizing similar electrolytes. We further show that these devices can withstand multiple (∼2500) mechanical bending cycles, without losing their energy storage capacities and are functional within the temperature range of 20 to 70 °C. Several strategies for enhancing the capacitive charge storage, such as physically stacking (in parallel) individual devices, or postproduction thermal annealing of electrodes, are also demonstrated. These findings demonstrated in this article provide tremendous impetus toward the realization of robust, stackable, and flexible all solid-state supercapacitors.

High Yield and High Volumetric Capacitance Activated Carbons by One‐step Homogeneous Activation of Diaphragma Juglandis Fructus for Supercapacitors

“…The CV and GCD curves of the QSSC are shown in Figure 5a and b, giving rise to a specific cell capacitance of 42.3 F g −1 at 0.5 A g −1 , corresponding to 169 F g −1 for a single electrode. Hence, the areal capacitance of AC‐1 in QSSC was 637 mF cm −2 , which was much higher than 14.5 mF cm −2 for carbon nanotubes in PVA/H 3 PO 4 gel electrolyte, [16] higher than 423.7 mF cm −2 for MnO 2 on activated carbon cloth in PVA/LiCl gel electrolyte, [17] comparable to 684 mF cm −2 for tailored tubular carbon in the PVA/Na 2 SO 4 gel electrolyte [18] . Three QSSCs were connected in series, achieving a cell voltage of 3 V which could illuminate an LED (Figure 5c and d).…”

Potentialities of fluorescent carbon nanomaterials as sensor for food analysis

“…Using this 'on-off' mode, fluorescent GQDs, nanocrystals, and CQDs could also be used to make colorimetric sensors. [44,46,48]…”

“…Because of their high sensitivity, high specificity, resistance to light scattering, and ease of use, fluorescent sensors are frequently used to detect biomolecules and metal ions. [28,[47][48][49][50] Fluorescence sensing systems have been constructed using advanced mechanisms like fluorescence resonance energy transfer (FRET), fluorescence quenching, electron transfer, dexter energy transfer, aggregation-induced emission enhancement, aggregation-induced emission quenching, aggregation-induced red-shift emission, and static quenching. [49,50] Because of their PL intensity, high quantum yield, outstanding stability, low cytotoxicity, tiny size, considerable biocompatibility, numerous low-cost sources, and good water solubility, carbon dots are commonly used in fluorescence analysis.…”

Preparation and Characterization of Physically Activated Carbon and Its Energetic Application for All-Solid-State Supercapacitors: A Case Study

“…Electrolytes play a significant role in SCs, whereas their stability, potential range, and ionic conductivity might affect the electrochemical performance . These SCs, which comprised liquid electrolytes, suffer from self-discharge, current leakage, explosion, corrosion, and bulky shape, as in the same case of liquid electrolytes in batteries. ,, Thus, significant attention has been given to assemble all solid-state SCs using solid–gel polymer electrolytes because they have high packaging flexibility, easy handling without leaking toxic liquids, advantageous mechanical properties, high ionic conductivity, appropriate electrolyte–electrode contact, and the capability to make thin films of desirable area where required. ,, Some of the recently reported polymer/gel electrolytes in SCs application are PMMA-EC-PC-LiClO 4 , , glycerol/KOH, PVA/H 2 SO 4 , PVA/H 3 PO 4 , and PVA/KOH . This paper presents the synthesis of a gel polymer electrolyte from polyvinyl alcohol and potassium hydroxide (PVA/KOH) and physically activated carbon (PAC) derived from date biomass.…”