Areal Energy Density Research Articles

3D printing and micro-spring architecting to reconcile ultra-high areal and volumetric energy density in highly loaded supercapacitors

The rigorous demand for significantly enhanced performance gains in metrics of areal and volumetric energy density from futuristic energy storage devices is driving current technological endeavors towards the design of highly-loaded energy storage systems. The advancement of supercapacitors has faced a formidable challenge in reconciling ultra-high areal (>1 mWh cm−2) and volumetric performance (>10 mWh cm−3) due to the intricate issue of efficient mass transport in a highly loaded environment. Here, the capability of 3D printing technology to architect open frameworks is well leveraged in conjunction with material interface decoration to create a heavily loaded pseudocapacitive MnO2 electrode of low structural tortuosity and fast surface reaction. By harnessing the potential of self-assembly, a robust electrode composed of ubiquitous micro-springs is developed, permitting elastic strain engineering that exceptionally augmented the volumetric performance while preserving efficient mass transport pathways for reasonable kinetics. Coupling with these features, a groundbreaking achievement is attained as an individual supercapacitor unit now boasts an unprecedented ultrahigh areal energy density of 2.83 mWh cm−2 and volumetric energy density of 37.3 mWh cm−3. The proposed strategy provides an informative roadmap benefiting the construction of next-level electrochemical energy storage devices.

Bioinspired Hierarchical Porous Architecture for Enhanced Kinetics and Mechanical Integrity in Thick Cathode.

Increasing the thickness of the electrodes is considered the primary strategy to elevate battery energy density. However, as the thickness increases, rate performance, cycling performance, and mechanical stability are affected due to the sluggish ion transfer kinetics and compromised structural integrity. Inspired by the natural hierarchical porous structure of trees, electrodes with bioinspired architecture are fabricated to address these challenges. Specifically, electrodes with aligned columns consist of tree-inspired vertical channels, and hierarchical pores are constructed by screen printing and ice-templating, imparting enhanced electrochemical and mechanical performance. Employing an aqueous-based binder, the LiNi0.8Mn0.1Co0.1O2 cathode achieves a high areal energy density of 15.1 mWh cm-2 at a rate of 1C at mass loading of 26.0mg cm-2,benefitting from the multiscale pores that elevated charge transfer kinetics in the thick electrode. The electrodes demonstrate capacity retention of 90% at the 100th cycle at a high current density of 5.2mA cm-2. To understand the mechanisms that promote electrode performance, simplified electro-chemo-mechanical models are developed,the drying process and the charge-discharge process are simulated. The simulation results suggested that the improved performance of the designed electrode benefits from the lower ohmic overpotential and less strain gradient and stress concentration due to the hierarchical porous architecture.

High-mass loaded redox-active lignin functionalized carbonized wood collector to construct sustainable and high-performance supercapacitors

Traditional electrode materials for supercapacitors often face issues like high toxicity, cost, and non-renewability. To address these drawbacks, biomass-based alternatives are being explored, aligning with green development trends. Herein, carbonized wood (CW) with rich pore structure and redox-active lignin are combined to fabricate an all-wood-based sustainable supercapacitor electrode material. Due to its inherent porous structure, CW provides a larger surface area for accommodating active materials ion, enabling the electrode to achieve a higher lignin loading capacity of 2.82–11.68 mg/cm2. Furthermore, the utilization of lignin as a substitute for conventional transition metal-based pseudocapacitor material functionalized CW endows the electrode with exemplary electrochemical performance while guaranteeing the comprehensive sustainability of the electrode. This synergy confers the electrode with exceptional electrical performance, yielding an areal capacitance of 960.7 mF/cm2 at a current density of 1 mA/cm2. The symmetric supercapacitors (SSC) manufactured by this composite electrode can achieve a notable areal energy density of 0.14 mWh/cm2 and a power density of 15.98 mW/cm2, while maintaining an outstanding capacitance retention rate of 81 % after 50,000 cycles at 20 mA/cm2. The manufacture of CW-lignin electrode underscores the potential of utilizing renewable biomass resources as alternatives for developing high-performance energy storage applications, thereby reducing negative environmental impacts.

Nitrogen-doped graphene quantum dot embedded polyaniline for the fabrication of high-performance flexible supercapacitor with enhanced cycling stability

This article explains the synthesis of high surface area nitrogen-doped graphene quantum dots embedded polyaniline (PANI) and its effectiveness in fabricating flexible printed supercapacitors. A noticeable change in polyaniline's morphology and specific surface area suggests the successful incorporation of graphene quantum dots into the polymer matrix. The synergistic interaction of polyaniline with graphene quantum dots is evident in its energy storage performance. The fabricated supercapacitor prototype with PVA/HCl gel electrolyte exhibited a very high areal capacitance of 128.01 mF cm−2, with an areal energy density of 11.40 μWh cm−2, and a power density of 640 μW cm−2 at 1.6 mA cm−2 current density. Most importantly, the developed supercapacitor exhibited 76.70% of original capacitance after 5000 galvanostatic charge-discharge cycles, which was found to be far better result than a supercapacitor fabricated with pristine polyaniline. Furthermore, the developed supercapacitor demonstrated excellent mechanical stability, retaining its performance at diverse angles and even after 4000 bending cycles. These characteristics make PANI/N-GQD-based supercapacitors appropriate for wearable devices requiring flexibility, cycling stability, and mechanical toughness.

Selective laser melting of 316L stainless steel: Porosity dependence on geometric feature size

This technical brief reports an experimental study on the effect of geometric feature size on the porosity in parts made via selective laser melting. Cylindrical features of different diameters were designed on a single part and printed using the same scan strategy. The resultant pores at different cylindrical feature diameters were captured by optical microscopy. The image processing results showed that as the cylindrical feature diameter decreased from 10 mm to 0.8 mm, the porosity increased from 0.11 % to 4.1 %, and the maximum pore size increased from 41.7 µm to 102.2 µm. To identify the reason for this interesting finding, the average areal energy density was calculated at each cylindrical feature diameter. The calculations showed that the different cylindrical feature diameters resulted in local energy density discrepancies. Because the scan strategy had a disparity for the border in comparison to the volume infill, and the areal ratio of the border to the volume infill naturally varied at different cylindrical feature diameters, the average areal energy density was found to vary significantly for cylindrical features of different diameters. The average areal energy density increased from 2.8 J/mm2 to 5.9 J/mm2 as the cylindrical feature diameter decreased from 10 mm to 0.8 mm. That change in the average areal energy density was identified as the cause for the porosity variation in this study.

MXene Supported Electrodeposition Engineering of Layer Double Hydroxide for Alkaline Zinc Batteries

AbstractThe main challenges faced by aqueous rechargeable nickel‐zinc batteries are their comparatively low energy density and poor cycling stability, mainly due to the limited capacity and reversibility of existing Ni‐based cathodes. Moreover, the preparation procedures of these cathodes are complex and not easily scalable, which makes them less promising for large‐scale energy storage. Herein, we utilized MXene as a functional additive to effectively improve the electrodeposition preparation of NiCo layered double hydroxides (LDH). Benefiting from the improved interfacial contact between nickel foam (NF) and platting solution and the enhanced ionic conductivity of platting product based on MXene additives, the resulting binder‐free NiCo LDH electrode can achieve ultrahigh areal loading (~65 mg cm−2) with abundant active surface for redox reactions and maintained short transport pathway for ion diffusion and charge transfer. Furthermore, the as‐fabricated alkaline NiCo LDH‐based battery delivers high discharge capacity, up to 20.2 mAh cm−2 (311 mAh g−1), accompanied by remarkable rate performance (9.6 mAh cm−2 or 148 mAh g−1 at 120 mA cm−2). Due to the high structural and chemical stability of MXenes/LDH‐based electrode, excellent cycling life can also be achieved with 88.6 % capacity retention after 10000 cycles. In addition, ultrahigh areal energy density (31.2 mWh cm−2) and gravimetric energy density (465 Wh kg−1) can be simultaneously achieved. This work has inspired the design of advanced cathode materials to develop high‐performance aqueous zinc batteries.

Hydrogen bond crosslinking hydrogel for high-performance ultra-low temperature MXene-based solid state supercapacitors

The electrochemical performance of aqueous electrolytes at low temperatures is frequently suboptimal due to their low freezing point (0 °C). In this study, we constructed MXene-based ultra-low temperature polyvinyl alcohol/nanocellulose-H2SO4 (PVA/CNF-H2SO4) hydrogel electrolytes utilising hydrogen bonding between water molecules and nanocellulose. The process results in a reduction in the amount of free water present in the hydrogel electrolyte, lowering its freezing point to -77.35 °C. PVA/CNF-H2SO4-based solid-state supercapacitors (C7-SSC) demonstrate a capacitance of up to 813 mF cm-2 at -50 °C, exhibiting high-rate performance at low temperatures. The capacitance remains at 45 F g-¹ at a current density of 20 A g-¹. The maximum areal energy and power densities of our C7-SSC achieve 113 μWh cm-² and 0.4 μW cm-² at -50 °C, respectively, surpassing the majority of state-of-the-art devices. This work provides new insights into MXene-based hydrogel manufacturing and expands the range of potential applications for such materials.

Vertical-channel hierarchically porous 3D printed electrodes with ultrahigh mass loading and areal energy density for Li-ion batteries

Lithium-ion batteries (LIBs) are renowned for their high energy density, long lifespan, and minimal self-discharge, making them a prominent power supply system. However, the persistent demand for improved energy density coupled with mechanical stability remains a significant challenge, as efforts to enhance electrode thickness or achieve geometric complexity through conventional ink-casting methods have yielded limited results. To tackle this challenge, we applied a three-dimensional (3D) printing technique to swiftly construct 3D thick electrodes with ultrahigh mass loading. Combined with unidirectional ice-templating process, high mass loading electrodes with hierarchically porous structures were successfully fabricated. The mass loading of the 3D electrodes can reach up to 73.83 mg cm−2, significantly enhancing the areal capacity. The low tortuosity and good mechanical resilience of these structures enable fast ion and charge transport, leading to significant improvements in areal energy density without sacrificing the power density. The assembled full cell exhibits an impressive areal capacity of 10.34 mAh cm⁻2 at 0.2 C and an excellent energy density of 18.41 mWh cm−2, surpassing other 3D printed lithium-ion batteries. This approach marks a significant advancement in electrode structural design towards higher areal capacity and energy density, showcasing the intriguing potential of 3D printed batteries for practical applications. Additionally, it also highlights the scalability and design versatility provided by 3D printing technique.

Process parameter translation strategies for variable directed energy deposition spot size using 316L, copper, and Inconel 625

Directed energy deposition (DED) is a form of additive manufacturing available across a variety of laser spot diameter values, often referred to as spot sizes. However, there is no method to easily transfer process parameters across discrete spot sizes, leading to DED process parameters that are equipment specific and not widely applicable. In this study, a strategy is proposed and investigated for five spot sizes that keep the areal energy density constant while varying power, feed rate, and powder flow during the deposition of 316L stainless steel. An assessment of trends in hardness and microstructure is possible due to the novel production of components of a single material across several spot sizes using a single nozzle on a single DED system. The proposed strategy was used to nullify the hardness drop during functional grading of Inconel 625 and pure copper, enabling fabrication of multi-material sample that does not compromise desirable properties. This application shows the value in establishing more efficient process parameter development and understanding spot size influences on geometric and material property flexibility, to enable a more diverse powder-based DED design space and to increase the industry adoption of DED systems.

Cobalt-ions pre-intercalation MnO2 nanosheet arrays on nickel foam achieving boosted electrochemical pseudocapacitance for supercapacitors

Metal oxide have attracted much attention as a pseudocapacitive electrode for high energy density supercapacitors (SCs). However, the battery-like charge storage mechanism based on ions diffusion and valence change for metal oxide would lead to a poor cycling stability and unsatisfied rate performance. Herein, cobalt ions pre-intercalation MnO2 nanosheet arrays on Ni foam (Co-MnO2/NF) was prepared as the cathode for SCs. The capacitive behavior of MnO2 was enhanced via cobalt introduction. The optimized Co-MnO2/NF-2 demonstrated improved pseudocapacitance and stability, with a specific capacitance of 405.6 mF cm−2 at 1 mA cm−2. It retained 90.5 % of its initial capacitance at 10 mA cm−2 after 5000 cycles, which was superior to that of pristine MnO2 (222.4 mF cm−2, 65.0 % after 1000 cycles), Co-MnO2/NF-1 (295.2 mF cm−2, 85.9 % after 1000 cycles), and Co-MnO2/NF-3 (349.9 mF cm−2, 84.9 % after 1000 cycles). The asymmetric aqueous supercapacitor consisted of Co-MnO2/NF-2 and N-doped porous carbon fiber (NPCF) electrodes with an operating potential of 2.0 V reaches a high areal energy density of 0.06 mWh cm−2 at a power density of 0.5 mWh cm−2.

Advanced Porous Gold-PANI Micro-Electrodes for High-Performance On-Chip Micro-Supercapacitors.

The downsizing of microscale energy storage devices is crucial for powering modern on-chip technologies by miniaturizing electronic components. Developing high-performance microscale energy devices, such as micro-supercapacitors, is essential through processing smart electrodes for on-chip structures. In this context, we introduce porous gold (Au) interdigitated electrodes (IDEs) as current collectors for micro-supercapacitors, using polyaniline as the active material. These porous Au IDE-based symmetric micro-supercapacitors (P-SMSCs) show a remarkable enhancement in charge storage performance, with a 187% increase in areal capacitance at 2.5 mA compared to conventional flat Au IDE-based devices, despite identical active material loading times. Our P-SMSCs achieve an areal capacitance of 60 mF/cm2, a peak areal energy density of 5.44 μWh/cm2, and an areal power of 2778 μW/cm2, surpassing most reported SMSCs. This study advances high-performance SMSCs by developing highly porous microscale planar current collectors, optimizing microelectrode use, and maximizing capacity within a compact footprint.

Architectural design and optimization of internal structures in 3D printed electrodes for superior supercapacitor performance

The architecture of electrodes plays a pivotal role in the transfer and transportation of charges during electrochemical reactions. Selecting optimal electrode materials and devising well-conceived electrode structures can substantially enhance the electrochemical performance of devices. This manuscript leverages 3D printing technology to fabricate asymmetric supercapacitor devices featuring regular layered configurations. By investigating the impact of various materials on the internal architecture of printed electrodes, we establish a stratified electrode structure with an orderly arrangement, thereby significantly improving asymmetric charge transfer between electrodes. The application of 3D printing technology to construct electrode structures effectively mitigates the agglomeration of electrode materials. The 3D-printed VCG//MXene devices demonstrate exceptional areal capacitance (205.57 mF cm−2) and energy density (60.03 μWh cm−2), with a power density of 0.174 W cm−2. Consequently, selecting appropriate materials for fabricating printable electrode structures and achieving efficient 3D printing is anticipated to offer novel insights into the construction and enhancement of miniature asymmetric micro-supercapacitor (MSCs) devices.

3D printing of customized Li-S microbatteries

Microbatteries serve as essential energy supply components in microelectronic, wearable and implantable devices. Despite recent efforts, developing lithium metal microbatteries with high energy densities and mechanical flexibility in structural design is still challenging, because of the poor interfacial stability and poor processability of lithium foil. Herein, we developed lithium-sulfur (Li-S) microbatteries with customized configurations using 3D printing techniques, which consist of a printable Li anode hosted within a graphene aerogel framework and a printable S cathode based on a carbon nanocages framework, featuring abundant porous structures and large specific surface areas. Consequently, the 3D-printed Li anode achieves over 900 hours of cycling with low overpotentials at an ultrahigh current density of 10 mA cm−2, and the 3D-printed S cathode delivers an ultrahigh capacity of 21.9 mAh cm−2 at the high thickness of 2.3 mm. Furthermore, the 3D-printed Li-S cell delivers an ultrahigh areal energy density of 48.4 mWh cm−2 at a high power density of 3.5 mW cm−2. The application potential of the 3D-printed customized Li-S microbatteries with arbitrary form factors is demonstrated by LED lighting and powering wearable sensor integration system, paving the way for their applications in miniaturized devices.

Supercapacitor properties of partially oxidised-MXene quantum dots/graphene hybrids: Fabrication of flexible/wearable micro-supercapacitor devices

Recently, combining the synergistic properties of two-dimensional (2D) and zero-dimensional (0D) materials has attracted significant attention for energy applications. Here, we report the synthesis and characterization of partially oxidised-MXene quantum dots (PO-MXQDs) and reduced graphene oxide composite (PO-MXQDs/rGO) and investigate the resulting composites for energy storage applications towards supercapacitors. Density functional theory (DFT) simulations are used to examine the electrical and structural features of PO-MXQDs/rGO by predicting the chemical interaction involving charge transfer from PO-MXQDs to rGO. The multilayer Artificial Neural Network (ANN) model with hyperparameter tuning was developed at different input parameters to optimize material compositions, concentrations, and types of electrolytes to obtain the suitable conditions for best supercapacitive performance. The optimized PO-MXQDs/rGO showed a specific capacitance value of 1137.8 F.g−1 and was utilized for the fabrication of flexible micro-supercapacitors (FMSCs) device through the mask-assisted vacuum filtration process and asymmetric coin-cell type supercapacitor devices (ACCDs). The FMSCs deliver a higher areal capacitance (5.26 mF.cm−2), high areal energy density (0.46 μWh.cm−2), high areal power density (210.48 μW.cm−2), and the FMSC device has ultra-high cyclic stability up to 30000 cyclic voltammetry (CV) cycles. This method provides an in-depth study on developing 0D-2D hybrid materials with the wisdom of machine learning (ML) and DFT toward energy storage applications.

Facile assembly of flexible, stretchable and attachable symmetric microsupercapacitors with wide working voltage windows and favorable durability

With the increasing development of intelligent robots and wearable electronics, the demand for high-performance flexible energy storage devices is drastically increasing. In this study, flexible symmetric microsupercapacitors (MSCs) that could operate in a wide working voltage window were developed by combining laser-direct-writing graphene (LG) electrodes with a phosphoric acid-nonionic surfactant liquid crystal (PA-NI LC) gel electrolyte. To increase the flexibility and enhance the conformal ability of the MSC devices to anisotropic surfaces, after the interdigitated LG formed on the polyimide (PI) film surface, the devices were further transferred onto a flexible, stretchable and transparent polydimethylsiloxane (PDMS) substrate; this substrate displayed favorable flexibility and mechanical characteristics in the bending test. Furthermore, the electrochemical performances of the symmetric MSCs with various electrode widths (300, 400, 500 and 600 μm) were evaluated. The findings revealed that symmetric MSC devices could operate in a large voltage range (0–1.5 V); additionally, the device with a 300 μm electrode width (MSC-300) exhibited the largest areal capacitance of 2.3 mF cm−2 at 0.07 mA cm−2 and an areal (volumetric) energy density of 0.72 μWh cm−2 (0.36 mWh cm−3) at 55.07 μW cm−2 (27.54 mW cm−3), along with favorable mechanical and cycling stability. After charging for ~20 s, two MSC-300 devices connected in series could supply energy to a calculator to operate for ~130 s, showing its practical application potential as an energy storage device. Moreover, the device displayed favorable reversibility, stability and durability. After 12 months of aging in air at room temperature, its electrochemical performance was not altered, and after charging-discharging measurements for 5000 cycles at 0.07 mA cm−2, ~93.6% of the areal capacitance was still retained; these results demonstrated its practical long-term application potential as an energy storage device.

Nanoconfined Supercooled Water in Hydrated Two-Dimensional Polyaniline for Sub-Zero Solid-State Zinc-Ion Hybrid Capacitor.

Solid-state electrochemical energy systems have attracted numerous attentions for their excellent performance, high safety, and low cost. Recently, ice of aqueous electrolytes is reported as a new kind solid-state electrolyte for low-temperature solid-state devices. However, the lack of kinetically favorable electrodes hampers the performance of this new class of icy electrolyte-based solid-state devices at sub-zero temperatures. In this work, a hydrated layered polyaniline cathode active material (h-LPANi) with nanoconfined supercooled water by metatungstate clusters is utilized to improve the performance of sub-zero solid-state zinc ion hybrid capacitors (ZIHCs). The interlayer confined hydrated network of h-LPANi improves kinetics, surpassing pristine polyaniline and conventional porous carbon-based active materials. At -15°C, the solid-state iced ZIHCs with h-LPANi cathode demonstrate an areal energy density of 580.0µWhcm-2 at 1.1mWcm-2 and 155.7µWhcm-2 at 43.3mWcm-2, surpassing other low-temperature solid-state ZIHCs with conventional cathodes.

β-ketoenamine-linked covalent organic frameworks ultrathin film for transparent supercapacitors with enhanced charge storage capability

With the development of electronic products toward optical transparency and intelligent portability, transparent supercapacitors (TSCs) have been considered as one of the ideal and efficient power sources. However, it is still a challenge to explore covalent organic frameworks (COFs) based transparent conductive electrodes (TCEs) with high photoelectric property and capacitive activity. Herein, β-ketoenamine DqTp (DAAQ-TFP, DAAQ = 2,6-diaminoanthraquinone, and TFP = 1,3,5-triformylphluroglucinol) COFs ultrathin films are synthesized for TCEs through the Schiff base reaction of DAAQ and TFP. The DqTp ultrathin films fully expose the redox-active anthraquinone moieties, shorten the ion/electron transport path, accelerate the transport and diffusion rate, and thus enhance charge storage capability. DqTp-1 TCEs possess the excellent optoelectronic property with optical transmittance (T550 nm) of 69.46%, sheet resistance (Rs) of 7.45 Ω sq−1, and remarkable areal capacitance (CA) of 355.67 μF cm−2. The corresponding asymmetric DqTp-1//PANI TSCs (T550 nm = 58.06%) yield a high CA of 64.55 μF cm−2 at 3 μA cm−2 and have a maximum areal energy density of 0.015 μWh cm−2 at 1.95 μW cm−2. After 5000 cycles, the capacitance retention is 96.9%. This work provides key insights into the design and synthesis of transparent redox-active COFs-based TSCs with excellent photoelectric property and enhanced charge storage capability.

A low-cost electrode based on Mg-Co double hydroxide for high energy density structural supercapacitors in civil engineering

In the field of construction, structural supercapacitors (SSCs) have been widely noticed due to their simultaneous functions of load-bearing and energy storage. Unfortunately, the currently available electrodes for SSCs are still aimed at application scenarios such as electronics and electric vehicles, and while their performance is good, they are not applicable to the construction sector, which is massive in scale and extremely cost-sensitive industry. Herein, after trade-off between cost and electrochemical performance, a novel low-cost 3D nanomaterial was designed through a facile approach aimed at increasing the areal energy density of SSCs. By growing Mg-Co double hydroxide nanomaterials directly on nickel foam, we achieved a large areal capacitance of 2577 mF/cm2 at 5 mA/cm2 (1136.7 F/g at 2.2 A/g). It also exhibits good cycling stability with a capacitance retention of 82.4 % after 10,000 cycles. In addition, SSCs using magnesium-cobalt double hydroxides achieves a high energy density of 285.6 μWh/cm3 at a power density of 6.31 mW/cm3, which is superior to previously reported structural devices. This demonstrates that Mg-Co double hydroxide electrode has good suitability with SSCs and effectively improves the areal energy density of SSCs. Our proposed method also provides a faster and more reliable pathway for low-cost electrode preparation in SSCs, which may lead to the development of a new generation of SSCs.

Effect of interlayer thickness on electrochemical properties and corrosion resistance of sputtered TiNxnm/Tixnm multilayer thin films

Three multilayers [TiNxnm/Tixnm/p-type Si (100)] (x = 2.5, 5, 10) were fabricated using a dc-magnetron sputtering to evaluate surface and interfacial effect on electrochemical properties for possible application in supercapacitor electrode materials. The (111) and (101) planes of TiN and Ti were observed at 36.50° and 40.19° respectively. TA, LA, and TO phonon modes were found at 254.12, 306.15, and 637.94 cm−1, respectively. The defect state distribution of Ti, N, and O was investigated from PL. XPS confirmed the Ti at. % of TiNxnm/Tixnm multilayers decreased from 43.07 to 12.04 and N at. % increased from 42.79 to 72.53 % as the x value decreased from 10 nm to 2.5 nm. The areal specific capacitance (Ca) and energy density (E) of the TiNxnm/Tixnm multilayer electrode increased with decreasing multilayer thickness. E varied from 0.27 to 1.37 mWhcm−2 and the power density (P) from 5.04 to 25.4 mWcm−2 for the multilayers. The diffusion coefficient (D) and total accumulated charge (Qin) decreased from 6.48 × 10−17 to 1.56 × 10−18 cm2/s and 1.82 to 1.64 C/cm2, respectively, for TiNxnm/Tixnm multilayers. The capacitive contribution was the highest in x = 10 (2.181 Av−1s). However, the diffusion-limited contribution was maximum in x = 5 (3.541 Av−1/2s1/2). The cyclic stability maintained at 85.4 % capacitive retention over 1000 cycles and the expansive potential window (up to 0.8 V in 1 M H2SO4) makes the multilayer thin films ideal for supercapacitor electrodes. Among all the samples, the TiN2.5nm/Ti2.5nm exhibited the highest Ca, E, and diffusion coefficient, originating from the smaller layer thickness, leading to more ohmic conductivity and facilitating the supercapacitive performance.

Comparative Study of Electrochromic Supercapacitor Electrodes Based on PEDOT:PSS/ITO Fabricated via Spray and Electrospray Methods.

PSS stands out as a leading commercial conducting polymer due to its excellent water dispersibility, controllable miscibility, adjustable conductivity, and ability to form films through various techniques. This study investigates the electrochemical and electrochromic performance of electrodes prepared by depositing PEDOT:PSS onto ITO surfaces by using two distinct methods: conventional spray coating and electrospray deposition. Detailed characterization of the prepared electrodes was performed by using atomic force microscopy, scanning electron microscopy, Fourier-transform infrared, and Raman spectroscopy techniques. Our findings reveal that electrodes fabricated via electrospray deposition (PEDOT:PSS/ITO electrode_2) significantly outperform those made by spray coating (PEDOT:PSS/ITO electrode_1). Specifically, electrode_2 exhibits a capacitance of 1678.60 μF cm-2, compared to 826.14 μF cm-2 for electrode_1, at a current density of 10 μA cm-2. PSS electrodes exhibit areal energy densities of 0.41 and 0.84 mW h cm-2, along with power densities of 4.96 and 4.97 μW cm-2, respectively. Moreover, electrode_2 demonstrates a high coloration efficiency of 84.32 cm2 C-1 and fast response times of 1.36 s for coloration and 0.98 s for bleaching. This study highlights the advantages of electrospray deposition over traditional methods, showcasing the potential of electrospray-prepared PEDOT:PSS electrodes for use in multifunctional energy storage devices.