Solid-state Symmetric Supercapacitor Device Research Articles

A novel chemical-free porous carbon micro-rods derived from used wooden chopsticks (CS) for solid-state symmetric supercapacitor device

Energy storage application technology is still in its infancy, and carbon-based materials have gained attention in recent years. The finding of low-cost carbon material with controllable characteristics for energy application is quite a complex thing. The major objective of this work is to carbonize used wooden chopsticks at various temperatures in order to create porous carbon materials. Electrochemical studies were tested in 1 M KOH electrolyte assessed by a three-electrode system for supercapacitor application. Among the prepared carbon materials, CS-7 material prepared at 700 °C with a carbon ratio of 88.2 %, demonstrated a high specific capacitance of 184.66 F/g at 0.3 A/g, and the material exhibited an excellent capacitance endurance of 96 % after 10,000 cycles. An asymmetric solid-state supercapacitor was developed for real-time application to study the electrochemical characteristics of the porous carbon material. This study clarifies the creation of complex porous carbon using waste biomass as an energy storage medium.

Walnut shell derived N, S co-doped activated carbon for solid-state symmetry supercapacitor device

The kernel of the walnut constitutes a nutrient-dense food source. However, the walnut shell is useless and was thrown away. Therefore, as a small initiative towards waste-to-wealth, herein we developed walnut shell-derived highly porous heteroatom (nitrogen and sulfur) doped activated carbon (NS-WAC) via KOH activation and post-processing treatment by thioacetamide (TAA). The NS-WAC exhibits a high specific surface area (SSA) and various particle size distribution (PSD) involving micropores, mesopores, and macropores, conferring substantial supercapacitor advantages. The NS-WAC possesses a significant proportion of mesopores, which can decrease the ion diffusion path length and improve ion transport efficiency. Hence, NS-WAC demonstrates promising electrochemical performance achieving a high gravimetric specific capacitance of 271.4 Fg−1 at 0.5 Ag−1 in 3 M KOH aqueous electrolyte. Furthermore, the solid-state symmetric supercapacitor (SSC) device exhibited a gravimetric specific capacitance of 52 Fg−1 and volumetric specific capacitance of 74.36F cm−3 at a current density of 0.5 Ag−1. This SSC device also exhibited a gravimetric energy density of 23.4 Wh Kg−1 at a power density of 250 W Kg−1 at a current density of 0.5 Ag−1. It showed superior cycle stability of 91.8% after 10,000 cycles at 5 Ag−1.

Mescoporous Nickel Titanate–Titanium Oxide Complex Material for Enhanced Energy Storage Application

Materials need to be engineered to make them device-ready. A mescoporous, a combination of meso- and microporous, nickel titanate–titanium oxide (m-NTTO) complex has been synthesized here using a simple sol–gel method for making a solid-state binder-free supercapacitor from the as-prepared powder. The m-NTTO sample, well characterized using electron microscopy, N2 adsorption–desorption isotherm, X-ray diffraction, and Raman spectroscopy was tested for its energy storage capabilities. The supercapacitive performance of m-NTTO is investigated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge (GCD). It shows a dominant electric double-layer capacitance with a total specific capacitance of 195 F/g at 10 mV/s and fast charging and slow discharging. Additionally, it exhibits high specific capacitance, excellent cyclic stability, and high retention. Using this sample, a prototype solid-state symmetric supercapacitor device has been fabricated to demonstrate excellent electrochemical performance with high specific capacitance, energy density, and power density was obtained, which suggests that the m-NTTO is suitable candidate material for energy storage application.

Novel interconnected hierarchical porous carbon derived from biomass for enhanced supercapacitor application

By offering a green and sustainable option to reusing biomass, the creation of energy harvesting/storage systems from biomass/waste materials has significant scientific and technological implications. To achieve the required applications in the fields of supercapacitor and conversion, microstructure management is crucial for carbon-based materials. Here, a facile production of heteroatom-doped porous carbon (HAPC) from Enhydra fluctuant leaves as electrode material for supercapacitor is demonstrated. Large specific-surface area and good pore-size distribution were achieved. An exceptional specific-capacitance (Csp) 428 F/g at 1 A/g in an acidic electrolyte was achieved. The solid-state symmetric-supercapacitor device (SSSD) produces the highest Csp of 113 F/g and 73.88 Wh/kg energy–density at 1 A/g, whereas 5.11 kW/kg power-density was achieved at 10 A/g. The SSSD exhibits outstanding durability, where it holds 94% of its Csp after 10,000 charge/discharge series.

InSitu Fabricated Small Organic Molecule-Anchored Bimetallic Hydroxide-based Nanohybrids for Symmetric Supercapacitor

Bioinspired nanohybrids offer promising electrode materials for energy storage applications. In this study, we have synthesized nanohybrid materials on carbon paper (CP) using the galvanostatic electrodeposition method to achieve the best combination of metal salts with a small organic moiety. The fabricated nanohybrids exhibit better energy storage properties. Among various nanohybrids, BSeYW/NCDH [BSe = benzo[2,1,3]selenadiazole, Y = l-tyrosine, and W = l-tryptophan; NCDH = nickel-cobalt dual hydroxides (2:2)] exhibits a high specific capacitance of 1734 F g–1 at 2 A g–1 and cyclic stability with 86.18% capacitance retention after 3000 cycles at 25 A g–1. Furthermore, the solid-state symmetric supercapacitor (SSC) device has been assembled by exploiting two binder-free BSeYW/NCDH(2:2) hybrid electrodes for practical applications. The SSC device has been electrochemically analyzed by cyclic voltammetry at different scan rates and potential windows. The galvanostatic charge–discharge (GCD) has been performed to investigate the capacitive behavior and cyclic stability. The fabricated SSCs deliver a maximum energy density of 18.27 W h/kg at a power density of 571.97 W/kg. In addition, the SSC device retains 85.25% at 7 A g–1 even after 5000 GCD cycles. Additionally, two assembled devices connected in series can operate a small fan and illuminate an LED. So, the electrochemical properties of BSeYW/NCDH nanomaterials could be used for the development of high-performance energy storage materials and devices.

Fabrication of Nanocluster-Aggregated Dense Ce2(MoO4)3 Microspherical Architectures for High-Voltage Energy Storage and High Catalytic Energy Conversion Applications

Recent progress has been made toward high-performance electrochemical energy storage and energy conversion devices to overcome the energy crisis. This article highlights the performance enhancement parameter of energy storage devices such as a symmetric supercapacitor and energy conversion such as methanol oxidation and water splitting studies for the generation of efficient oxygen and hydrogen. We have prepared a dense cerium molybdate microspherical architecture by the hydrothermal route, and further physical characterization has been performed to evaluate the structural parameters. Charge storage contributions, external surface charge, and internal surface-accumulated charge are calculated by Dunn’s and Trassati’s approaches. A solid-state symmetric supercapacitor device has been assembled, which exhibits outstanding electrochemical performance with a device capacity of 198 C g–1 at 1 A g–1, a large electrochemical potential window of 2.2 V, an enormous cyclic retention of 89.5% after 10,000 cycles, a maximum specific energy of 60.5 W h kg–1, and a maximum specific power of 10.6 kW kg–1. Furthermore, the prepared microspherical architectures were evaluated for oxygen/hydrogen evolution reactions and methanol oxidation. The prepared electrode exhibits excellent oxygen evolution performance, while keeping the lowest overpotential as 316 mV, and for hydrogen evolution reaction, the overpotential was obtained as 178 mV. The microspherical architecture electrode also exhibits attractive catalytic performance for methanol oxidation and exhibits a maximum current density of 157 mA cm–2, while having an onset potential of 1.314 V (versus RHE). Thus, the prepared nanocluster-aggregated microspherical architecture of Ce2(MoO4)3 can efficiently serve as the next-generation multifunction materials for energy storage and energy conversion applications.

Highly Porous Holey Carbon for High Areal Energy Density Solid-State Supercapacitor Application.

Biomass materials are perceived as sustainable, carbon-rich precursors for the fabrication of carbon materials. In this study, we demonstrated the capacitance performance of biomass-derived carbon, produced by using golden shower tree seeds (GTs) as carbon precursors and potassium ferrate (K2FeO4) as the activation agent. The as-prepared porous carbon (GTPC) possessed an ultrahigh specific surface area (1915 m2 g−1) and abundant pores. They also exhibited superior electrochemical performance, owing to their well-constructed porous structure, high surface area, and optimized porous structure. Optimized activated carbon (GTPC-1) was used to assemble a symmetric solid-state supercapacitor device with poly(vinyl alcohol) (PVA)/H2SO4 as a solid-state gel electrolyte. The device exhibited a maximum areal energy density of 42.93 µWh cm−2 at a power density of 520 µW cm−2.

High performance binary composite (Sr(OH)2/CoO(OH)) thin film for solid state supercapacitor

The fabrication of supercapacitor with efficient power and energy densities with capacity retention is currently leading need in each corner of the globe. In this regard, we have deposited nanoflakes tuberose structured Sr(OH)2/CoO(OH) thin films via layer by layer method over the stainless steel substrate. The crystalline nature and functional groups present in the electrode have been analysed by X-ray diffraction and Fourier transform analysis respectively. The chemical composition and oxidation states present within sample have been vetted via X-ray photoelectron spectroscopy. The nanoflakes grown over the tuberose surface have been revealed by scanning electron microscopy. The electrochemical performance and sustainability of the electrode have been analysed by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The deposited electrode exhibits an excellent specific capacitance of 1544.8 F g−1 and cycle stability ~67% over 12,000 cycles. A solid-state symmetric supercapacitor device, exhibiting outstanding electrochemical performance with a specific capacitance of 155.2 F g−1 and cycle stability ~71% up to 6000 cycles, has been fabricated. This device has a high energy density of 49.9 Wh kg−1 and power density of 7088.5 W kg−1. To show the practical application, blue, green, red, and white coloured light emitting diodes have been illuminated by the fabricated device. These results exhibit that this electrode is a suitable candidate for next-generation energy storage devices.

Coconut Shell-Derived Activated Carbon for High-Performance Solid-State Supercapacitors

Coconut shells, low-cost and renewable agro-wastes, were used as a starting material in the synthesis of hierarchical activated carbons via hydrothermal, KOH-activation, and carbonization techniques. The ratio of KOH to hydrochar was varied in a systemic manner to study how it influences the texture and electrochemical behavior of the capacitor. Coconut shell-based carbon coated on nickel foams presented a surface area of 1567 m2 g−1, with micropores as well as mesopores widely distributed. The sample showed superior electrochemical performance, attaining 449 F g−1 at 1 A g−1 in 6 M LiNO3 aqueous solution. The solid-state symmetric supercapacitor device delivered a specific capacitance of 88 F g−1 at 1 A g−1 and a high energy density of 48.9 Whkg−1 at a power density of 1 kW kg−1. At a wide voltage window of 2.0 V, the sample was highly stable during the cycle test, showing a 92% capacitance retention at 2 A g−1 after cycling for 5000 times. The superior performance is due to the sample possessing great BET surface area, a good distribution of pores, and the usage of a suitable electrolyte. This facilitates an electrical double layer that can be deployed for applications to store energy.

SILAR synthesized nanostructured ytterbium sulfide thin film electrodes for symmetric supercapacitors

A simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method was used for synthesis of ytterbium sulfide (Yb2S3) thin film. The valence states and crystal structure of Yb2S3 thin film material were identified using X-ray photoelectron spectroscopy and X-ray diffraction analysis, respectively. Wettability test of Yb2S3 thin film showed hydrophilic nature with the value of 21.70°. The surface texture of Yb2S3 thin film was examined using field emission scanning electron microscope (FE-SEM). The specific surface area and pore size distribution were measured using the Brunarer-Emmet-Teller (BET) and Barrette-Joynere-Halendar (BJH) methods. The supercapacitive performance of Yb2S3 thin film was studied using cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance tests in 1.0 M Na2SO4 aqueous solution. The Yb2S3 electrode showed specific capacitance (Cs) of 181 F g−1 with 83% capacity retention up to 3000 CV cycles. The aqueous symmetric supercapacitor (ASSc) device with the configuration of Yb2S3/Na2SO4/Yb2S3 and solid-state symmetric supercapacitor (SSSSc) device of configuration of Yb2S3/PVA-Na2SO4/Yb2S3 were fabricated. The ASSc device showed better supercapacitor performance (energy density (E.D.) of 8.25 Wh kg−1 at power density (P.D.) of 0.56 kW kg−1) than the SSSSc device.

Synthesis of CoO-Decorated Graphene Hollow Nanoballs for High-Performance Flexible Supercapacitors

The formation of thin and uniform capacitive layers for fully interacting with an electrolyte in a supercapacitor is a key challenge to achieve optimal capacitance. Here, we demonstrate a binder-free and flexible supercapacitor with the electrode made of cobalt oxide nanoparticle (CoO NP)-wrapped graphene hollow nanoballs (GHBs). The growth process of Co(OH)2 NPs, which could subsequently be thermally annealed to CoO NPs, was monitored by in situ electrochemical liquid transmission electron microscopy (TEM). In the dynamic growth of Co(OH)2 NPs on a film of GHBs, the lateral formation of fan-shaped clusters of Co(OH)2 NPs spread over the surface of GHBs was observed by in situ TEM. This CoO-GHBs/CC electrode exhibits high specific capacitance (2238 F g-1 at 1 A g-1) and good rate capability (1170 F g-1 at 15 A g-1). The outstanding capacitive performance and good rate capability of the CoO-GHBs/CC electrode were achieved by the synergistic combination of highly pseudocapacitive CoO and electrically conductive GHBs with large surface areas. A solid-state symmetric supercapacitor (SSC), with CoO-GHBs/CCs used for both positive and negative electrodes, exhibits high power density (6000 W kg-1 at 8.2 Wh kg-1), high energy density (16 Wh kg-1 at 800 W kg-1), cycling stability (∼100% capacitance retention after 5000 cycles), and excellent mechanical flexibility at various bending positions. Finally, a serial connection of four SSC devices can efficiently power a red light-emitting diode after being charged for 20 s, demonstrating the practical application of this CoO-GHBs/CC-based SSC device for efficient energy storage.

Supramolecular-induced confining methylene blue in three-dimensional reduced graphene oxide for high-performance supercapacitors

Adding redox-active species into the electrolyte can supply extra capacitance to the carbon-based supercapacitors. However, the devices may suffer from serious self-discharge caused by the shuttling and intermixing of charged active species between the electrodes. Confining these active species in a solid-state electrode material is an effective strategy to avoid this. Inspired by this, we fabricate a three-dimensional reduced graphene oxide confined methylene blue composite via a supramolecular strategy, combined with a hydrothermal reduction and a freeze-drying process. Benefited from the porous and conductive structure of the product, the fast-reversible electrochemical reaction of methylene blue, and the spatial confinement effect of the methylene blue confined in reduced graphene oxide, the as-prepared product exhibits a high-rate capability (311 and 262 F g−1 at 1 and 20 A g−1, respectively) and an excellent cycle stability (96% capacitance retention after 10000 cycles) in a three-electrode system. Moreover, a solid-state symmetric supercapacitor device based on the as-prepared product delivers the maximum energy density of 8.2 Wh kg−1 and outstanding cycle stability. This supramolecular-induced confining active species in reduced graphene oxide strategy provides insight into the fabrication of other high-performance graphene-based pseudocapacitors.

Preparation of boron-doped diamond nanospikes on porous Ti substrate for high-performance supercapacitors

The study reports on the preparation of boron-doped diamond nanospikes (BDD-NSs), supported on porous titanium (Ti) substrate, using reactive ion etching (RIE) with oxygen plasma and their investigation as an electrode material for supercapacitors. The above architecture contributes to an ideal pathway for supercapacitors with good stability and high specific capacitance. As a result, the BDD electrode etched for 5 min (BDD-NSs-5) achieved good performance with a high specific capacitance of 70.6 mF cm−2 at a current density of 0.32 mA cm−2 and a capacitance retention of 84.3% after 15,000 cycles. Moreover, the BDD-NSs-5 electrode was assembled into a symmetric supercapacitor device. The device achieved high energy and power densities of 9.24 mJ cm−2 and 1.26 mW cm−2, respectively, implying enhanced potential for real-time applications. For practical application, the BDD-NSs-5 electrode was used for rotating a home-designed windmill device and the solid-state symmetric supercapacitor device can light up a red LED for 20 s after being charged to 3.0 V.

Chemical synthesis of nano-grained ytterbium sulfide thin films for supercapacitor application

Nano-grained ytterbium sulfide (Yb2S3) thin film is deposited by an inexpensive chemical bath deposition (CBD) method with excellent supercapacitive performance. The formation of Yb2S3 thin film is confirmed from XRD, FT-Raman, and XPS studies. The nano-grains like surface morphology of Yb2S3 thin film is observed using scanning electron microscopy and transmission electron microscopy techniques. The Yb2S3 film shows hydrophilic nature with a contact angle value of 61.2°. The electrochemical supercapacitive properties of Yb2S3 thin film are studied using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The Yb2S3 thin film exhibits a specific capacitance of 184.6 F g−1 in 1 M KOH electrolyte at a 5 mV s−1 scan rate. The symmetric solid-state supercapacitor device of configuration Yb2S3/KOH-PVA/Yb2S3 shows a specific capacitance of 15 F g−1 and energy density of 13.80 W kg−1 at power density 0.55 kW kg−1. The device exhibits 78% capacitive retention over 3000 cycles.

Solid-state symmetric supercapacitor based on Y doped Sr(OH)2 using SILAR method

Supercapacitor is one of the most promising and emerging type of energy storage devices having the merits of both conventional battery and traditional capacitor. In this regard, we have deposited Yttrium doped Strontium hydroxide thin films on stainless steel substrate with the help of a facile, cost-effective successive ionic layer adsorption and reaction technique at room temperature without using any binder. Doping of Yttrium into Strontium hydroxide enhances both electronic conductivity and electrochemical performance of the electrode for energy storage. Nanorods like structure with the tuberose morphology has been obtained with the help of field emission scanning electron microscopy. The cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements show the pseudocapacitive battery like response. Among all the synthesised materials, 1.0 at. % Yttrium doped Strontium hydroxide shows a high specific capacity of 705.3 C g−1 at 0.4 mA current rate and stability of ∼82% at 2.5 mA current rate. The prototype light-weight solid-state symmetric supercapacitor device of Yttrium doped Strontium hydroxide electrodes has been fabricated by sandwiching PVA-Na2SO4 gel. Thus, we observe that this device has potential applications for the next-generation cost effective energy storage system.

Binder free lanthanum doped manganese oxide @ graphene oxide composite as high energy density electrode material for flexible symmetric solid state supercapacitor

The present work is about synthesis of La doped (1–5 vol %) manganese oxide (MnO2) @ graphene oxide (GO) composite electrode. The thin films are obtained using a facile and binder free successive ionic layer adsorption and reaction (SILAR) method. The scanning electron microscopic image of 3%La–MnO2@GO composite thin film shows porous spongy-like nanoparticles. Nitrogen desorption analysis shows that mesoporous sheets of 3%La–MnO2@GO exhibits large surface area up to 149 m2 g−1. The highest electrochemical specific capacitance of 729 F g−1 at the scan rate of 5 mV s−1 is obtained for 3%La–MnO2@GO electrode. The 3%La–MnO2@GO thin film electrode exhibits 94% capacitive retention over 5000 CV cycles. The flexible symmetric solid state supercapacitor device of configuration SS/3%La–MnO2@GO/PVA-Na2SO4/3%La–MnO2@GO/SS operating in potential window 1.8 V shows maximum specific capacitance of 140 F g−1 with energy density of 64 Wh kg−1 at power density of 1 kW kg−1 and capacitive retention of 90% after 5000 CV cycles at the scan rate of 100 mVs−1.

Intercalation pseudocapacitance in chemically stable Au-α-Fe2O3-Mn3O4 composite nanorod: Towards highly efficient solid-state symmetric supercapacitor device

Pseudocapacitance generally appears due to the surface or near-surface reversible Faradaic reactions. In this regard, 2D layered materials have gained substantial attention as a potential source for driving a myriad of energy storage applications owing to their unique surface-structure relationship. Here, we have demonstrated that a pseudocapacitive mechanism becomes increasingly operative when H+ ions are intercalated easily into the enhanced van der Waals gap of layered material α-Fe2O3 in Au-α-Fe2O3-Mn3O4 nanocomposite. Theoretical studies have shown an enhancement of van der Waals gap which is attributed to the intercalation of Au into the layers of α-Fe2O3. Structural and compositional characterizations have been carried out in detailed by different physical methods and are supported by theoretical studies. Electrochemical measurements show excellent specific capacitance of 580 F g−1 at 1 A g−1 along with improved capacity retention compared to the mother component α-Fe2O3 (205 F g−1 at 1 A g−1) in 0.5 M H2SO4 electrolyte in a potential window of 1.2 V. Further, electrokinetic measurements revealed that total charge stored in the nanocomposite is based on a dominant capacitive mechanism (70% of the total capacitance) along with diffusive mechanism (30% of the total capacitance) at scan rate 5 mV s−1 whereas, α-Fe2O3 exhibits 34% capacitive and 66% diffusive at same scan rate. The synthesized composite nanorod as an efficient electrode material in a solid-state symmetric supercapacitor device exhibits excellent energy density of 36.12 Wh kg−1 and power density of 1994 W kg−1 at 1 A g−1 and 10 A g−1, respectively with outstanding stability (89%) up to 2000 successive charge-discharge cycles at 10 A g−1. This work may offer a new scope for further development of intercalation pseudocapacitive nanomaterials towards achieving high energy storage supercapacitors.

Self-Standing Metallic Mesh with MnO2 Multiscale Microstructures for High-Capacity Flexible Transparent Energy Storage.

Flexible transparent electrochemical supercapacitors are critical components for the rapid development of fully flexible transparent electronics; however, typical flexible transparent supercapacitor electrodes store limited energy due to the requirements of transparency. Self-standing core-shell structure metal oxide mesh electrodes with metal oxide as active "shell" and metallic mesh as current collector "core" are efficient for simultaneously achieving high capacity, flexibility, and transparency. In this work, we perform a morphology-controlled electrodeposition of MnO2 on a self-standing flexible transparent metallic Ni mesh electrode to achieve a high-capacity flexible transparent supercapacitor electrode. Under optimized conditions, the MnO2 nanosheet-composed flowerlike multiscale microstructure was constructed. The open, loose, and porous MnO2 multiscale microstructure "shell" and high electrical conductivity of self-standing metallic mesh "core" synergistically enable efficient ionic and electronic transport and meanwhile retain high structural stability. The metal oxide mesh electrode yields an outstanding areal capacitance of 1.15 F/cm2 at an optical transmittance of 69.4% and excellent cycling stability. The symmetric solid-state supercapacitor device exhibits a high areal capacitance value (78.46 mF/cm2), superior cycling life, as well as high optical transmittance and mechanical flexibility, superior to the most reported flexible transparent supercapacitors. This work provides a comprehensive understanding on how to achieve high-capacity flexible transparent supercapacitor electrodes and solid-state devices.

Textile-based RGO-muffled cobalt (II, III) oxide hybrid nano-architectures for flexible energy storage device

Recent century is enduring a passionate development of hardback electronic devices that promised to be more reliable power sources with higher energy density and long-term stability. To push up the energy density limit of solid-state symmetric supercapacitor (SSC) devices here we report RGO-muffled cobalt (II, III) oxide nanowires hybrid nanostructures as a potential aspirant in the field of flexible and portable electronics. The eco-friendly chemical route was followed to synthesize RGO enfolded cobalt (II, III) oxide nanowires on flexible carbon fabric substrate (CONW-RGO), which disclosed prevailing electrochemical performances rather than cobalt (II, III) oxide nanowires on flexible carbon fabric (CONW). The specific capacitance of CONW-RGO electrode we achieved 1110 F/g at current density 1 A/g, measured in 3-electrode configuration. Also solid state symmetric device performances were investigated which provide extensive potential window of 0 to 1.5 V. As-fabricated device dispensed higher energy and power density 34.78 Wh/kg (0.214 mWh/cm3) and 3.6 kW/kg (23 mW/cm3) respectively and exhibited outstanding cyclic performance by retaining 86.4% capacitance after 10,000 cycles. This is the very first time report of using CONW-RGO electrode as binder-free flexible SSC device with moderately widen potential window.

Solution processed nanostructured cerium oxide electrode: Electrochemical engineering towards solid-state symmetric supercapacitor device

Present work portrays the surface morphology dependent electrochemical behaviors tuned by annealing the chemical bath deposited (CBD) cerium oxide electrodes. The altered nanostructure properties are well-supported by in-depth structural and morphological analysis. Cerium oxide electrode annealed at 200°C exhibits good surface properties enabling maximum electro-active porous cavities to penetrate electrolyte ions towards enhanced electron transfer. Consequently, the electrode exhibits maximum specific capacitance of 750F/g with remarkably stable charge-discharge cycles. Fabricated symmetric solid-state supercapacitor device impressively expands potential window to 1.2V with the aid of PVA-LiClO4 gel electrolyte with a peak specific capacitance of 321.3F/g with top-up of 61.4Wh/kg specific energy. The series combination of two devices confirms the strong energy storage ability by glowing ‘VNIT’ acronym designed through 21 red LEDs from the practical point of view.