High-performance Supercapacitors Research Articles

Tetraethylphosphonium tetrafluoroborate electrolyte for paving the way to construct high-power and high-voltage supercapacitors

Phosphonium-containing electrolytes offer a new avenue for advancing high-performance supercapacitors. In this study, for the first time, we investigated the physical and electrochemical characteristics of a new phosphonium salt—tetraethylphosphonium tetrafluoroborate (TEPBF4) in various solvents including acetonitrile (AN), propionitrile (PN), propylene carbonate (PC), and trimethyl phosphate (TMP). Our investigations revealed that TEPBF4/AN electrolytes demonstrated high solubility (2.15 M), high ionic conductivity (52.2 mS cm−1), and wide electrochemical stability windows (≥4.7 V), suggesting that TEPBF4/AN emerges as a compelling alternative to conventional ammonium salts in AN for developing high-power and high-voltage supercapacitors. Our results also showed that supercapacitors based on 1 M TEPBF4/AN achieved the highest capacitance (24.7 F g−1), superior rate performance, highest energy (24.9 Wh kg−1) and power densities (6752 W kg−1) among the investigated electrolytes. Furthermore, it retained 75 % of its capacitance after 1000 h float test at a high working voltage of 3.2 V, which significantly outperformed other supercapacitors using conventional ammonium salts in AN.

An Investigation into the Influence of Graphene Content on Achieving a High-Performance TiO2-Graphene Nanocomposite Supercapacitor.

This study presents the synthesis of TiO2-graphene nanocomposites with varying mass ratios of graphene (2.5, 5, 10, 20 wt. %) using a facile and cost-effective hydrothermal approach. By integrating TiO2 nanoparticles with graphene, a nanomaterial characterized by a two-dimensional structure, unique electrical conductivity and high specific surface area, the resulting hybrid material shows promise for application in supercapacitors. The nanocomposite specimens were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman microscopy, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Additionally, supercapacitive properties were investigated using a three-electrode setup by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) tests. Notably, the TiO2-20 wt. % rGO nanocomposite exhibited the highest specific capacitance of 624 F/g at 2 A/g, showcasing superior electrochemical performance. This specimen indicated a high rate capability and cyclic stability (93 % retention after 2000 cycles). Its remarkable energy density and power density of this sample designate it as a strong contender for practical supercapacitor applications.

Fabrication and characterization of Sb2O3-MoS2 nanocomposites for high performance supercapacitor applications.

Binary nanocomposite-based electrodes have been studied extensively in recent times owing to their multiple oxidation states, excellent physico-chemical features, and combined morphology, which are suitable for increasing the electrochemical performance of supercapacitors. The present work deals with Sb2O3-MoS2 NCs electrode for supercapacitor applications. The XRD, Raman, SEM, EDX, HRTEM, SAED and XPS characterizations have been studied to analyze the phase formation, vibrational modes, morphology, elemental composition and binding energies of the prepared Sb2O3-MoS2 NCs electrode material, as well as their electrochemical measurements such as CV, GCD, and EIS have been analyzed. The developed Sb2O3-MoS2 NCs electrode provides a high specific capacitance of 454.3 F/g at the current density of 1 A/g. Further, the hybrid supercapacitor device has been constructed which shows 104.04 F/g of specific capacitance at 2 A/g and manifests a good energy density of 24.42 Wh/kg at a power density of 1299.89 W/kg. Additionally, the hybrid device Sb2O3-MoS2//AC exhibits a good capacitive retention of 90.6% and a coulombic efficiency of 100.45% at 10 A/g over 8000 cycles.

Influence of Ni-doping on CuCo2O4 electrode for enhanced supercapacitor performance and sustainable energy storage

This work provides a revolutionary strategy for creating high-performance supercapacitors by designing and fabricating a unique nanostructured bimetallic oxide electrode. The proposed electrode leveraged the synergistic effects of metal oxides to enhance both energy density and charge-discharge kinetics. Ni-doped CuCo2O4 nanostructures (Cu1-xNixCo2O4) were synthesized in incremental order (x = 0.0, 0.05, 0.10, and 0.15) by facile sol-gel auto-combustion route. The nanostructures analyzed through x-ray diffraction, FTIR spectroscopy, Micro-Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy revealed the single phase and polycrystalline nature of CuCo2O4, with some impurity phases of CuO. The surface morphology studies showed numerous pores among the grains of Cu1-xNixCo2O4. Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical performance of synthesized Cu1-xNixCo2O4 samples. In a 3 M KOH electrolyte solution, the Cu1-xNixCo2O4 electrodes with x = 0.05 exhibited 2340 Fg−1 specific capacitance at 5 mVs−1, demonstrating superior electrochemical performance with excellent rate capability. Furthermore, it exhibited 35.88 Whkg−1 energy density, an exceptional 2484.74 Wkg−1 power density, and retained 99.9 % capacitance after 5000 cycles, demonstrating good stability. The results suggest that porous bimetallic oxide nanostructures can be promising candidates for the development of high-performance, environmentally friendly supercapacitors.

Biogenic synthesis of nickel cobaltite nanoparticles via a green route for enhancing the photocatalytic and electrochemical performances

Green synthesis aligns with the global demand for eco-friendly and sustainable technologies, reducing the dependency on harmful chemicals and high-energy processes typically used in conventional synthesis techniques. This study highlights a novel green synthesis route for nickel cobaltite nanoparticles (NiCO2O4 NPs) utilizing Hyphaene thebaica extract as a natural reducing and stabilizing agent. The synthesized NiCO2O4 NPs, with sizes ranging from 20 to 30 nm, exhibited uniform diamond-like structures as confirmed by SEM and TEM imaging. XRD analysis verified the polycrystalline nature of these nanoparticles, while EDS measurements confirmed the elemental composition of Ni and Co. The presence of functional groups was subsequently verified through FT-IR analysis, and Raman spectroscopy further confirmed phase formation. Electrochemical evaluations revealed significant pseudocapacitive behavior, showing a specific capacitance of 519 F/g, demonstrating their potential for high-performance supercapacitors. To further assess the applicability of the synthesized NiCO2O4 NPs, their photocatalytic activity against methylene blue (MB) dye was investigated, resulting in a 99% degradation rate. This impressive photocatalytic efficiency highlights their potential application in environmental remediation. Overall, this work underscores the significant potential of green synthesis methods in producing high-performance nanomaterials while simultaneously reducing environmental impact and promoting sustainable development.

Synthesis, analysis and characterization of Mo-doped Fe3O4 nanoparticles decorated on rGO as an anode for high-performance supercapacitors

Synthesis, analysis and characterization of Mo-doped Fe3O4 nanoparticles decorated on rGO as an anode for high-performance supercapacitors

One-Step Wet-Spinning of High-Energy Density Coaxial Fibrous Supercapacitors Based on In Situ Carbon-Modified Nitrogen-Doped MXene Nanosheets.

Fibrous supercapacitors (SCs) are emerging promising power sources for flexible/wearable electronics and have attracted an extensive amount of attention from researchers. However, the low energy density has always hindered their further development. Here, a coaxial fibrous SC (CFSC) was fabricated by one-step wet-spinning combined with an electrodeposition strategy. Benefiting from the large surface area and abundant pore structure of carbon-modified nitrogen-doped MXene nanosheets (NS), as well as the high conductivity of silver (Ag) NS, the electrolyte ion/electron transport paths are significantly improved. Furthermore, the distributed GO in the P(VDF-HFP) separator could form a high-speed continuous ion transport channel, thus enhancing the ionic conductivity. At a power density of 40-200 μW cm-2, the CFSC shows a high energy density of 0.7-3.39 μWh cm-2. The as-prepared CFSC also maintains an excellent capacitance retention rate of 90.3% even after 15 000 charge-discharge cycles. This work provides a general strategy for manufacturing high-performance, flexible, and wearable SCs.

Boosting the Electrical Transfer by Molybdenum Doping for Robust and Flexible NiSe-Based Supercapacitor.

NiSe is a promising electrode material for enhancing the energy density of supercapacitors, but it faces challenges such as sensitivity to electrolyte anions, limited specific capacity, and unstable cycling. This study employs a strategy of metal atom doping to address these issues. Through a hydrothermal reaction, Mo-doped NiSe demonstrates significant improvement in electrochemical performance, exhibiting high capacity (799.90Cg-1), splendid rate performance, and excellent cyclic stability (90% capacity retention). The introduction of Mo induces charge redistribution in NiSe, leading to a reduction in the band gap. Theoretical calculation reveals that Mo doping can effectively enhance the electrical conductivity and the adsorption energy of NiSe. A flexible printed hybrid Mo-doped NiSe-based supercapacitor is fabricated, demonstrating superior electrochemical performance (367.04mFcm-2) and the ability to power timers, LEDs, and toy fans. This research not only deepens the understanding of the electrochemical properties of metal-doped NiSe but also highlights its application potential in high-performance supercapacitors.

3D porous PEDOT/MXene scaffold toward high-performance supercapacitors

3D architectures of conductive polymer, especially PEDOT hold great promise in energy storage and conversion fields. However, the facile construction of 3D PEDOT and its functionalization have still been challenges due to its poor processability. Herein, the fabrication of 3D porous PEDOT:PSS and its functionalization with MXene are realized synchronously through a simple and low-cost self-assembly process. The prominent capacitive performance of MXene, excellent chemical stability of PEDOT:PSS and 3D porous architecture with inhibited aggregation of MXene nanosheets, large amount of active sites, and electrolyte storage chamber endow the PEDOT/MXene-based porous structure with superior capacitive performance than individual PEDOT:PSS or MXene porous and flat structures. Furthermore, the PEDOT/MXene-based porous structure can be applied as a flexible scaffold for the deposition of conductive polymer to construct excellent electrodes for supercapacitors (SCs). When polypyrrole (PPy) is deposited, the prepared porous PEDOT:PSS/MXene/PPy electrode exhibits a high gravimetric specific capacitance of 345 F g−1 at a current density of 0.5 A g−1 and a remarkable capacitance retention of 89 % over 5000 cycles. Based on it, an asymmetric supercapacitor (ASC) with a high energy density of 56.34 Wh kg−1 at the power density of 120 W kg−1, and a capacitance retention of 75 % after 5000 cycles is developed. Besides, the porous PEDOT:PSS/MXene/PPy can be constructed on various substrates in any pattern with high design freedom, thus enabling customizable electrochemical performance. When constructing on a flexible substrate, excellent deformation-tolerant performance is shown. This work provides a high-performance electrode for SCs, as well as a universal route for the construction and functionalization of 3D PEDOT-based structures.

Highly conductive, mechanically robust and multi-purpose carbon aerogel composites derived from waste bread enable high-performance symmetric supercapacitors

Sustainable biomass-based carbon aerogels have attracted extensive concerns in the area of energy storage and wearable sensory electronics. However, the pristine porosity and low weight of aerogels result in unsatisfactory mechanical and electrical properties, limiting their practical applications. Herein, activated porous carbon (APC), reduced graphene oxide (rGO) and carbon nanoparticles (CNP) are utilized as raw materials to develop a novel type of hierarchically waste bread-derived carbon aerogel via a stepwise activation/calcination strategy. The obtained bread-derived carbon aerogels, named APC-rGO/CNP, exhibits an outstanding electrical conductivity (∼3.23 S cm−1) and a high compressive modulus (∼124.60 MPa) by the synergistic bonding interactions. As a supercapacitor electrode, the APC-rGO/CNP composite manifests an excellent capacitance of 474.8 F g−1 (1.0 A g−1). Furthermore, an all-solid-state symmetric APC-rGO/CNP//APC-rGO/CNP supercapacitor with polyvinyl alcohol/potassium hydroxide (PVA/KOH) gel electrolyte realizes an energy density of 17.4 Wh kg−1 at 895 W kg−1. Notably, even under large compressive stress of 20 kPa, the supercapacitor still achieves a high energy density of 25.6 Wh kg−1 at a power density of 822.8 W kg−1, as well as an excellent capacitance retention of 93.8 % over 10,000 cycles. Finally, we demonstrate the potential of the APC-rGO/CNP composite as a responsive pressure sensor with an ultra-wide detecting span of 0–3 MPa and a moderate sensitivity of 0.22 kPa−1, which can detect keyboard pressing and fist clenching movements distinctively. Overall, the desirable mechanical performances and electrical conductivity of the APC-rGO/CNP composites facilitate the development of versatile nanomaterials to exploit state-of-the-art wearable electronics.

Single proton anti-freezing hydrogel electrolyte with enhanced ion migration number enabling high-performance supercapacitor

Compared with traditional binary ion electrolytes, single-ion electrolytes have higher ion migration number and can avoid concentration polarization. In this work, single proton hydrogel electrolytes were prepared by one-step free radical polymerization of acrylamide and 2-acrylaminoamido-2-methyl-1-propane sulfonic acid in ethylene glycol (EG)/water binary solvent. The electrolyte possesses good mechanical strength and excellent anti-freezing ability. A high conductivity of 1.28 mS cm−1 at −40 °C is achieved by adjusting monomer ratio and EG content. The proton hopping along the ion channel formed by the anionic polymer chain and the Grotthuss transport are responsible for the high conductivity. An extremely high ion migration number of 0.87 is obtained. The fixed anionic group endows the hydrogel electrolyte with good anticorrosion ability. The hydrogel electrolyte assembled supercapacitor (SC) exhibits excellent electrochemical performance in a wide temperature range from −40 °C to 60 °C and can be stored at −30 °C for 10 months without capacitance attenuation. The capacitance retention rate of the SC is as high as 92% after 15,000 cycles at both room temperature and − 40 °C. The single proton hydrogel electrolyte provides a new route for the further development of storage device based proton transport.

Chemical reduction-induced defect-rich bismuth oxide-reduced graphene oxide anode for high-performance supercapacitors

We prepare bismuth oxide-reduced graphene oxide (Bi2O3-rGO) composite anode using a one-step chemical precipitation/reduction method. Under a reducing atmosphere, oxygen atoms on the surface of Bi2O3 are gradually removed and neighboring oxygen atoms migrate to the surface, leaving oxygen vacancies. Defective Bi2O3 enhances the number of active sites, providing additional pseudocapacitive performance. The transition metal oxide-based Bi2O3 acts as an anode, providing capacitive performance that far exceeds that of conventional carbon materials. Moreover, the introduction of rGO forms a conductive network for Bi2O3, improving capacitive contribution and ion diffusion capabilities for the electrode. The Bi2O3-rGO-100 (GO added at 100 mg) exhibits a high specific capacitance of 1053F/g at 1 A/g, significantly higher than that of Bi2O3 (866F/g). The Bi2O3-rGO-100 anode and Ni3Co2-rGO cathode are assembled into a battery-type supercapacitor. The coin-cell device achieves an energy density of 88.2 Wh kg−1 at a power density of 850 W kg−1. The Ni3Co2-rGO//Bi2O3-rGO-100 pouch-cell device demonstrates an extremely low Rct of 0.77 Ω. At a power density of 850 W kg−1, the energy density reaches 118.5 Wh kg−1, and remains 67.4 Wh kg−1 at 8500 W kg−1.

Synthesis of ZnO and NiO nano ceramics composite high-performance supercapacitor and its catalytic capabilities

NiO and ZnO mixed nanocomposites were manufactured using the solution combustion process. As-prepared samples were analyzed using XRD. The XRD shows an average crystallite size of 35–40 nm. The elemental composition determined by EDS indicates a nearly equal proportion of Ni and Zn, with an atomic ratio of Ni/Zn = 0.96. The specific capacitances of NiO is 295.5 Fg-1, ZnO is 117.3 Fg-1 and ZnO/NiO nanocomposites is 561.75 Fg-1 which are more than NiO and ZnO alone. This study shows that constructing binary oxide nanocomposites is an approach for developing high-performance supercapacitor electrode materials. Experimental observations on catalytic activity revealed that NiO/ZnO increased catalytic activity. Furthermore, adding NiO to ZnO in the composite increased the overall amount of oxygen vacancies in the samples. Our research lays the door for a simple, inexpensive, nontoxic, and quick technique to synthesize binary transition metal oxide-based electrode materials for high-performance supercapacitors.

Cross-linked and pillared graphene with nonconventional redox benzidine dimethyl ether for high-performance supercapacitors

To hinder Van der Waals-induced agglomeration between graphene sheets to increase specific surface area, and to supplement pseudocapacitance, graphene processing with active molecules is highly effective. Redox polymers and quinones, instead of aromatic ethers, were popular candidates. They were universally blended with graphene sheets through noncovalent modes, leading to issues of electrochemical stability and rate capability, etc. Herein, we broke through stereotype to develop aromatic ethers–benzidine with two remote methoxyls (i.e. 3,3′–dimethoxybenzidine, DMeOBD)–to covalently functionalize graphene, obtaining the cross-linked and pillared graphene electrode material (DMeOBD-rGO). It exhibited redox activity and featured a combination of electrochemical double layer supercapacitor and pseudocapacitor, thus yielded an enhanced specific capacitance of 363 F g−1. When assembled into two-electrode solid-state supercapacitors, the whole devices also delivered an impressive specific capacitance of 263 F g−1, and a high energy density of 13.2 Wh kg−1, along with excellent rate capability and cycling stability.

Utilizing Manganese Phase Transition in Bioabsorption Synthesis of MnO@Carbon Composites for Enhanced High-Performance Supercapacitors

Utilizing Manganese Phase Transition in Bioabsorption Synthesis of MnO@Carbon Composites for Enhanced High-Performance Supercapacitors

In situ grown heterostructures based on MAX-derived TaO2F nanorod and TaC (MXene) nanosheet for high-performance hybrid supercapacitors

Two-dimensional MXene-based interface heterostructures have an undeniable position in the energy storage systems, particularly supercapacitors, due to their unique microstructure and electrochemical properties. However, the selection of materials in heterogeneous structures and the assembly strategy often have often have a significant impact on the properties of heterogeneous structures. This study proposes a in situ grown strategy for constructing TaO2F@TaC nano-heterostructures consisting of one-dimensional TaO2F nanorods combined with two-dimensional TaC nanosheets derived from the precursor MAX phase. The complex etching and growth mechanism from MAX to 1D/2D TaO2F@TaC is reasonably inferred. The construction of TaO2F@TaC nano-heterostructures effectively addresses the issue of MXene to restack and improves the poor conductivity of TaO2F. Density functional theory (DFT) calculations validated the electronic structure and charge distribution at the heterostructure interface, demonstrating its capability for electron conduction and ion transport. Moreover, the hybrid supercapacitor (HSC) based on TaO2F@TaC exhibited superior energy density (153.4 μWh cm−2 at a power density of 222.2 μW cm−2) and excellent cycle stability. The prepared quasi-solid-state supercapacitor (QSC) also shows a capacitance of 457.4 mF cm−2, and retains 99.38 % capacity after 8200 cycles. This work innovatively bypasses the multi-step process of preparing MXene heterostructures and provides a new approach for developing MXene-based electrode materials to enhance the performance of hybrid supercapacitors.

Enhanced electrochemical validation of metal organic frameworks-derived TiO2/Fe-TiO2 as an active electrode for supercapacitors

AbstractDeveloping supercapacitor materials that are both efficient and durable, with high cycle life and specific energy, poses a significant challenge due to issues in electrodes such as volume expansion and electrode degradation that occur over time. This work reports a simple, novel, and cost-effective synthesis method to fabricate high surface area “Iron (Fe) doped TiO2 materials” via the metal-organic framework (MOF) route for supercapacitor application. Morphological analysis revealed a disc-like shaped pattern for pristine TiO2 (PT), and a cuboid form for Fe-doped TiO2 (FeT). The electrochemical investigation of MOF-derived PT and FeT electrode materials demonstrated the superior performance of FeT. Cyclic Voltammetry revealed enhanced electrochemical properties in FeT. Galvanostatic charge-discharge measurements confirmed FeT’s higher energy storage capacity, reaching a maximum specific capacitance of 925 Fg− 1. Long-term cycling tests exhibited excellent stability, with FeT retaining 67% of its initial capacitance after 6000 cycles and showing prolonged self-discharge. Overall, the results underscore the potential of Fe-doped TiO2 for high-performance supercapacitors.

Novel three-dimensional architectured ZnMgAl ternary layered double hydroxide@reduced graphene oxide nanocomposites as electrode material for high-performance supercapacitor

Ternary layered double hydroxides (LDH) have recently attracted immense attention owing to their stupendous features, such as fine compositional tuning, multiple valence states, and superior electrochemical activity. Moreover, their intriguing structures and distinctive physiochemical properties delineate them as an exemplary material to serve as electrodes for high-performance supercapacitors (SCs). The present work reports the in-situ synthesis of Zinc Magnesium Aluminium LDH (ZMA) integrated with reduced graphene oxide (rGO) through a single-step hydrothermal approach. The resulting novel ternary ZMA@rGO nanocomposite (ZMAG) possesses a unique architecture incorporating hierarchical 3D nanoflowers of ZMA embedded on graphene nanosheets. The porous morphology of LDH improves interfacial charge transport, which results in more faradaic reactions at the electrochemically active sites. In addition, the conductive graphene nanosheets render a high specific surface area, endowing excellent capacitive behavior. The amalgamated electrochemical properties of ZMA and rGO develop a competent electrode material (ZMAG) for SCs. The ZMAG2 nanocomposite having ZMA and rGO in 1:1, evinces a specific capacitance (Cs) of 656.7 F/g at a current density (Id) of 1 A/g. Furthermore, the asymmetric supercapacitor (ASC) features admirable cycle stability (retains 89% of initial capacitance after 15,000 charge/discharge cycles). Herein, the real-time application of ZMA@rGO//AC ASC has also been demonstrated. Therefore, hierarchical porous nanostructure proclaims new prospects for fabricating proficient electrode materials for energy storage devices.

Carbon-modified NiCo2O4 as an electrode material for supercapacitors

Transition metal oxides are a promising class of electrode materials for pseudocapacitors due to their high electrochemical activity and eco-friendly nature. However, they possess poor intrinsic conductivity which results in the low energy density of the assembled supercapacitors. In this study, electrodes composed of amorphous C-modified NiCo2O4 (C/NiCo2O4/NF) on nickel foam substrate were prepared by electrochemical deposition and thermostatic heating method. The incorporation of amorphous C compensates for the low electrical conductivity of NiCo2O4 materials, thereby significantly enhancing the electrochemical performance. The galvanostatic charge-discharge (GCD) test results reveal an impressive specific capacitance of 379.4 mF/cm2 at a current density of 1.5 mA/cm2, and with a capacitance retention rate of 87.1 %. In addition, the symmetric supercapacitor assembled using C/NiCo2O4 electrode materials exhibits exceptional energy density and power density, reaching maximum values of 522.3 μWh/cm2 and 900 μW/cm2 respectively. The device is capable of illuminating LED for up to 8 min, further demonstrating its practical applicability. These results underscore the feasibility and promise of C/NiCo2O4 as an electrode material for the advancement of high-performance supercapacitors.

Instantaneous reduction of inkjet-printed graphene oxide on PVDF nanofibers for high-performance ultralight flexible supercapacitors

As the demand for innovative electronic devices continues to grow, flexible electronic products which offer a solution capable of adapting to various shapes and deformations, are increasingly gaining prominence. This study innovatively uses electrospun polyvinylidene fluoride (PVDF) nanofibers as substrates and employs reactive inkjet printing (RIP) technology to deposit and instantaneously reduce graphene oxide (GO), fabricating ultralight flexible all-solid-state supercapacitors. To verify that PVDF nanofibers as substrates can facilitate the uniform deposition of GO ink during inkjet printing and prevent the dispersion of GO into the internal structure, thereby achieving good capacitive performance with the fewest layers of printing, this study analyzes and compares the capacitive performance differences among 1rGO/PVDF, 3rGO/PVDF, and 5rGO/PVDF samples. The results have been confirmed that the GO ink was effectively instantaneously in-situ reduced by l-ascorbic acid (AA) to rGO by RIP system, and the specific capacitance of 1rGO/PVDF electrode was founded of 83.29 F/g at a current density of 2 A/g from the GCD analysis with a corresponding energy density of 7.5 Wh kg−1 and power density of 1.04 kW kg−1. The 1rGO/PVDF supercapacitor exhibits excellent electrochemical stability, maintaining 93 % efficiency after 4000 charge-discharge cycles at a current density of 2 A/g.