In-plane Micro-supercapacitors Research Articles

3D Printed Stamps for Transfer Printing of Flexible and Wearable Supercapacitors

In recent times, there has been an increasing demand for portable, lightweight, and flexible electronic devices. These electronic devices are required in healthcare, robotics, sports, defence, and other applications. Energy storage unit is one of the key requirements of these electronics and solid-state micro-supercapacitors (MSCs) are preferred for flexible and wearable electronics.[1,2] However, conventional methods of manufacturing MSCs are complex, time-consuming, and costly. This work aims to explore an alternative approach to developing MSCs by transferring electronic inks onto paper, textiles, and other flexible substrates using 3D-printed stamps. Different in-plane MSCs with varying finger widths and interspace gaps were fabricated to find the optimum electrochemical properties. The developed devices exhibit excellent electrochemical performance including high power density, high energy density, excellent lifetime, and excellent flexibility under different mechanical deformation conditions (such as bending, rolling, folding, etc.). This approach has a huge potential for fabrication of next-generation electronics for flexible and wearable electronic applications.

Picosecond ultraviolet laser patterned in-plane asymmetric micro-supercapacitors with high-precision capacity matching

Extensive exploratory research on in-plane asymmetric micro-supercapacitors (AMSCs) involves developing various fabrication techniques for in-plane electrodes to streamline the manufacturing process and expanding the operating voltage window (OVW) to increase energy density. Herein, we prepare MXene (Ti3C2Tx) and laser-induced graphene (LIG) electrodes using picosecond ultraviolet laser etching and laser direct writing, respectively, to construct in-plane MXene//LIG AMSCs. The high precision of laser technology guarantees the preparation of in-plane asymmetric electrodes with an interelectrode spacing of 100 μm. Additionally, we adjust the electrode width ratio of the positive and negative electrodes to attain high-precision capacity matching. This capacity matching method not only broadens OVW to 1.2 V, but also increases the energy density up to 1.9 times. The picosecond laser patterning construction approach and the capacity matching method in this work provide new perspectives for in-plane asymmetric supercapacitors.

Controlling surface oxygen vacancies in 3D networked MnO2 based nanocomposites for high performance flexible in-plane micro-supercapacitors

The rising demand for portable, flexible, and eco-friendly electronic devices has spurred the development of micro-supercapacitors (mSCs) as compact and versatile energy storage components. Electric double-layer (EDL)-mSCs incorporating graphene electrodes offer swift and reversible charge/discharge processes, making them suitable for sustainable device systems. To greatly enhance the electrochemical performance of mSCs, we present a direct synthesis and fabrication of surface oxygen vacancy-controlled MnO2 with a Faradaic capacitive behavior on a porous graphene electrode with 3D networked framework. Surface oxygen vacancies in MnO2 were created through hydrogen peroxide (H2O2) treatment, which led to an increase in the electrode's conductivity and facilitating electrochemical reactions due to creation of the local electric field at the vacancy sites. We achieved 251 % and 163 % increase in capacitance of surface oxygen vacancy controlled MnO2/graphene nanocomposite electrode compared to the porous graphene electrode and pristine MnO2/graphene electrode, respectively, and exhibited a volumetric energy density of 3.61 Wh/L. Furthermore, the mSCs demonstrated excellent cyclic stability and mechanical flexibility under various strain conditions. This surface oxygen vacancy-controlled MnO2/graphene nanocomposite electrode represents a simple and efficient strategy for high-performance and versatile energy storage components, with potential applications in electronic devices and sustainable energy systems.

Fabrication of Ni-Cr-FeOx ceramic supercapacitor electrodes and devices by one-step electric discharge ablation

This investigation addresses the need in the development of a facile, low-cost and computer-aided design method to fabricate ceramic supercapacitors, based on patterned metal oxide films. It is motivated by the promising advantages of planar electrode arrangement for the fabrication of ceramic supercapacitors operating at extremely high charge-discharge rates. Herein, one-step electric discharge ablation (EDA) technique is developed for fabricating Ni-Cr-FeOx electrodes using commercial 304 stainless steel current collectors for the first time. The binder-free, noble materials-free, toxic chemical-free and conductive additives-free Ni-Cr-FeOx based in-plane microsupercapacitors (IMSC) are fabricated by the EDA technique. The obtained IMSC delivers a high areal capacitance of 38.3 mF cm−2 at 1 mV s−1 and shows superior capacitive behavior at an ultrahigh scan rate of 152,000 mV s−1, which is >760 times higher than the reported values for ceramic metal oxide based electrodes in the literature. This one-step, low-cost, environmental friendly, and automatic fabrication method is promising for the scale-up synthesis of various ceramic metal oxides and fabrication of supercapacitor devices.

Architectural engineering of vertically expanded graphene-CoMn2O4 compounds based interdigital electrode for in-plane micro-supercapacitor

Structurally engineered carbon allotropes and their composites are widely applicable in various electronic/electrochemical devices including energy storage. Herein, we develop an efficient method to fabricate graphene/ceramic hybrid nanostructure based in-plane micro-supercapacitors (MSCs). Via CO2-laser irradiation method, MSCs patterns consisting of CoMn2O4 nanoparticles incorporated in vertically structured laser-induced graphene (CMOLIG) were formed on a freestanding graphene oxide film. The process is extremely convenient, since the laser irradiated CMOLIG patterns serve as the in-plane MSCs electrode, while the untreated graphene oxide acts as the substrate. MSCs with enhanced performance can be fabricated with the CMOLIG hybrid electrode patterns that are made of CoMn2O4 nanoparticles with pseudocapacitive properties anchored on vertically structured high-quality graphene film with excellent electrical property and high surface area. Notably, the CMOLIG electrode patterns exhibit enhanced specific capacitance with fast redox kinetics. Using the technique, customized in-plane MSCs arrays are also fabricated, which demonstrated controllable output voltage and capacitance depending on the array configuration to suit the requirements of various wearable microelectronics.

Synthesis of hierarchically porous carbon materials from nanocapsule based on interfacial polymerization of galla chinensis extract for all-solid-state supercapacitor application

In this study, we have demonstrated a facile and economic approach to synthesize hierarchically porous carbon materials (HPCMs) derived from galla chinensis. We mixed the aqueous crude extract of galla chinensis and the triblock copolymer Pluronic F127 solution to lead to an interfacial polymerization reaction, finally resulting in the formation of nanocapsule in the solution. Compared to the soft template approach in which F127 is used as a template agent, the nanocapsule approach enables larger specific surface area (SSA) HPCM, which is attributed to the change of state of F127 in solutions measured by confocal Raman spectroscopy. We find that the optimal product called GC04 owns a high specific surface area (SSA) 236 m2∙g−1 without any post activation treatment. Benefiting from the high SSA, GC04 exhibits 33% higher areal capacitance than its counterparts obtained via conventional soft template approach in a well-sealed in-plane micro-supercapacitor (IMSC). Therefore, the present investigation provides a new approach for the high value use of galla chinensis, which is low-cost and highly sustainable for synthesis of HPCMs.

Self-Powered Integrated Sensing System with In-Plane Micro-Supercapacitors for Wearable Electronics.

Self-powered integrated sensor with high-sensitivity physiological signals detection is indispensable for next-generation wearable electronic devices. Herein, a Ti3 C2 Tx /CNTs-based self-powered resistive sensor with solar cells and in-plane micro-supercapacitors (MSCs) is successfully realized on a flexible styrene-ethylene/butylene-styrene (SEBS) electrospinning film. The prepared Ti3 C2 Tx /CNTs@SEBS/CNTs nanofiber membranes exhibit high electrical conductivity and mechanical flexibility. The laser-assisted fabricated Ti3 C2 Tx /CNTs based-MSCs demonstrate a high areal energy density of 52.89 and 9.56µWhcm-2 with a corresponding areal power density of 0.2 and 4mWcm-2 . Additionally, the MSCs exhibit remarkable capacity retention of 90.62% after 10 000 cycles. Furthermore, the Ti3 C2 Tx /CNTs based-sensor exhibits real-time detection capability for human facial micro-expressions and pulse single under physiological conditions. The repeated bending/release tests indicate the long-time cycle stability of the Ti3 C2 Tx /CNTs based-sensor. Owing to the excellent sensing performance, the sensing arraywasalso fabricated. It is believed that this work develops a route for designing a self-powered sensor system with flexible production, high performance, and human-friendly characteristics for wearable electronics.

Laser-patterned PEDOT:PSS-aramid nanofiber composite electrodes for in-plane supercapacitors with high performance, shape-diversity and ultrahigh deformation resistance

The rapid development of portable and wearable modern electronics is in urgent need of the compatible energy storage devices, among which the flexible in-plane micro-supercapacitor (MSC) has emerged as a promising candidate. In this work, a facile and efficient laser-ablation technique was used to fabricate high performance metal-free all-solid-state in-plane MSCs with dimethyl sulfoxide-treated composite electrode (D-PA) composed of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS, PH1000) and aramid nanofibers. The effect of D-PA mass loading on the electrical and electrochemical properties of electrodes and devices was studied. The optimal MSC delivers high areal capacitance (15.4 mF/cm2 at 2 mV/s), superior charge/discharge cycling stability (capacitance hardly changes after 10,000 cycles), excellent rate performance (11.1 mF/cm2 at 3 mA/cm2) and ultrahigh resistance to arbitrary and extreme mechanical deformation (including circle-bending, free-twisting and multi-folding), which are superior to many state-of-the-art PH1000-based MSCs. Furthermore, performance of the shape-diverse device is easily tailored by series and/or parallel integration without usage of the metallic component. Such high performance MSC presents a great potential application in portable and wearable electronics even under severe deformed states.

Bending Resistance Covalent Organic Framework Superlattice: “Nano-Hourglass”-Induced Charge Accumulation for Flexible In-Plane Micro-Supercapacitors

HighlightsCovalent organic framework (COF) superlattices were assembled by free-standing COF nanofilms based on the van der Waals force for the first time.Geometry-induced “nano-hourglass” steric configuration in COF superlattice can provide rapid charge transfer/accumulation at heterojunction interface for in-Plane Micro-supercapacitors.The prepared MSC exhibited a high energy density of 63.2 mWh cm−3 even after high-angle and repeat arbitrary bending from 0 to 180°.

Flexible in-plane Micro-Supercapacitor Prepared by Laser Annealing and Ablation of a Graphene/Polyamide Acid Composite

An in-plane micro-supercapacitor (MSC) which has a unique interdigitated electrode structure with through-holes was developed by laser annealing and ablation of a carbon/polyamide acid composite coating on a polyimide film. The laser annealing of a composite film consisting of multi-layer graphene or activated carbon remarkably lowered the resistivity by laser carbonization of polyamide acid. The laser ablation was conducted to make an interdigitated electrode with a through-hole structure. The through-holes were effective to improve the capacitance of an in-plane MSC by enhancing the ion diffusion in carbon layer because the surface area of carbon layer can be increased using front and back sides of a polyimide film. An in-plane MSC consisting of an asymmetric interdigitated electrode which had an activated carbon composite layer on the front side and a multi-layer graphene composite on back side of a polyimide film showed the improvement of capacitance.

Progress and prospects of graphene use for in-plane micro-supercapacitors

Progress and prospects of graphene use for in-plane micro-supercapacitors

Water Peel-Off Transfer of Electronically Enhanced, Paper-Based Laser-Induced Graphene for Wearable Electronics.

Laser-induced graphene (LIG) has gained preponderance in recent years, as a very attractive material for the fabrication and patterning of graphitic structures and electrodes, for multiple applications in electronics. Typically, polymeric substrates, such as polyimide, have been used as precursor materials, but other organic, more sustainable, and accessible precursor materials have emerged as viable alternatives, including cellulose substrates. However, these substrates have lacked the conductive and chemical properties achieved by conventional LIG precursor substrates and have not been translated into fully flexible, wearable scenarios. In this work, we expand the conductive properties of paper-based LIG, by boosting the graphitization potential of paper, through the introduction of external aromatic moieties and meticulous control of laser fluence. Colored wax printing over the paper substrates introduces aromatic chemical structures, allowing for the synthesis of LIG chemical structures with sheet resistances as low as 5 Ω·sq-1, translating to an apparent conductivity as high as 28.2 S·cm-1. Regarding chemical properties, ID/IG ratios of 0.28 showcase low defect densities of LIG chemical structures and improve on previous reports on paper-based LIG, where sheet resistance has been limited to values around 30 Ω·sq-1, with more defect dense and less crystalline chemical structures. With these improved properties, a simple transfer methodology was developed, based on a water-induced peel-off process that efficiently separates patterned LIG structures from the native paper substrates to conformable, flexible substrates, harnessing the multifunctional capabilities of LIG toward multiple applications in wearable electronics. Proof-of concept electrodes for electrochemical sensors, strain sensors, and in-plane microsupercapacitors were patterned, transferred, and characterized, using paper as a high-value LIG precursor for multiples scenarios in wearable technologies, for improved sustainability and accessibility of such applications.

In situ preparation of FeOx nanoparticles embedded N-doped laser-induced graphene for flexible in-plane micro-supercapacitors

In situ preparation of FeOx nanoparticles embedded N-doped laser-induced graphene for flexible in-plane micro-supercapacitors

Ultra-foldable integrated high-performance in-plane micro-supercapacitors from laser-induced selective metallization

The popularity of flexible and wearable electronic devices has stimulated the development of flexible energy storage devices, in which micro-supercapacitor (MSCs) are the most promising. Herein, we demonstrated a novel strategy for scalable fabrication of copper-nickel-polypyrrole (Cu-Ni-PPy) MSCs devices through laser-induced selective metallization of Cu interdigitated electrode combined with electroplating Ni and electrochemical deposition active material of PPy. The prepared Cu-Ni current collector exhibit high electrical conductivity and mechanical flexibility. Moreover, the obtained Cu-Ni-PPy MSCs devices display a large areal capacitance of 126.67 mF/cm2 and a high volume energy density of 31.78 and 5.39 mWh/cm3 at the corresponding power density of 0.15 and 7.5 W/cm3, respectively. Besides, the MSCs exhibit remarkable capacity retention of 94.8% after 10,000 bending cycles and 89.3% after 10,000 cycles. The wireless charging of the MSCs device can be realized by reasonably designing the wireless charging coil (WCO) for electromagnetic conversion. It is believed that this work provides insight into the manufacture of portability and flexibility of miniaturized energy storage devices.

Ultralight self-charging triboelectric power paper with enhanced on-chip energy storage

The ever-growing demands of loads and sensors of the Internet of things (IoT) in fifth generation (5 G) era spur innovation and development of environmentally sustainable power supplies. Herein, a self-charging power source based on paper is designed to harvest mechanical energy produced by hand movements and store them in micro-supercapacitors (MSCs). The triboelectric nanogenerator (TENG) with free-standing structure and the in-plane MSCs are integrated on one piece of paper, ruling out extra processes for wire bonding, circuit pad, and packaging, and thus effectively simplifying the self-powering system. The pencil lead material is drawn onto the paper to obtain in-plane interdigital MSCs and followed by surface functionalization with small pseudocapacitive aromatic molecules. High areal capacitance of 6.96 mAh g−1 cm−2 is achieved, which is about 6 times as much as pure pencil lead coating. As a proof-of-concept demonstration, some microelectronic devices like a wireless positioning sensor can be powered by our all-in-one self-charging power paper.

Laser Processing of Flexible In-Plane Micro-supercapacitors: Progresses in Advanced Manufacturing of Nanostructured Electrodes.

Flexible in-plane architecture micro-supercapacitors (MSCs) are competitive candidates for on-chip miniature energy storage applications owing to their light weight, small size, high flexibility, as well as the advantages of short charging time, high power density, and long cycle life. However, tedious and time-consuming processes are required for the manufacturing of high-resolution interdigital electrodes using conventional approaches. In contrast, the laser processing technique enables high-efficiency high-precision patterning and advanced manufacturing of nanostructured electrodes. In this review, the recent advances in laser manufacturing and patterning of nanostructured electrodes for applications in flexible in-plane MSCs are comprehensively summarized. Various laser processing techniques for the synthesis, modification, and processing of interdigital electrode materials, including laser pyrolysis, reduction, oxidation, growth, activation, sintering, doping, and ablation, are discussed. In particular, some special features and merits of laser processing techniques are highlighted, including the impacts of laser types and parameters on manufacturing electrodes with desired morphologies/structures and their applications on the formation of high-quality nanoshaped graphene, the selective deposition of nanostructured materials, the controllable nanopore etching and heteroatom doping, and the efficient sintering of nanometal products. Finally, the current challenges and prospects associated with the laser processing of in-plane MSCs are also discussed. This review will provide a useful guidance for the advanced manufacturing of nanostructured electrodes in flexible in-plane energy storage devices and beyond.

Space-Partitioning and metal coordination in Free-Standing Covalent organic framework Nano-Films: Over 230 mWh/cm3 energy density for flexible in-Plane Micro-Supercapacitors

In-plane micro-supercapacitor (MSC) is an important energy storage equipment for the power-source backup in miniaturized electronics. Covalent organic framework (COF) with the regular porous structure and high stability is emerging as a promising flexible MSC electrode material. Herein, the large-area shape-customizable COFTAPB-DHPA free-standing nano-film with the thickness of ∼11 nm was prepared via the surfactant-monolayer-assisted interfacial synthesis (SMAIS) method, followed by space-partitioning (covalent bond with ionic liquid, IL-COFTAPB-DHPA) and metal coordination (Co2+, Co-COFTAPB-DHPA) two strategies to enhance the capacitance performances. The MSC-COFTAPB-DHPA, MSC-IL-COFTAPB-DHPA and MSC-Co-COFTAPB-DHPA were fabricated directly by using corresponding as-prepared COF films as flexible electrodes. The maximum energy density value of MSC-IL-COFTAPB-DHPA (139.7 mWh/cm3) and MSC-Co-COFTAPB-DHPA (230.4 mWh/cm3) is 106% and 240% higher than the reported highest value in the reported two-dimensional (2D) material based MSCs at this stage, respectively. This work provides the potential MSC application direction of the large-area and crystalline 2D-COF nano-film.

NiCoB based in-plane energy storage textile with enhanced mechanical performance

The fast development of wearable electronics has propelled the research focusing on in-plane energy storage garments. The mechanical stability of textile devices is vital for their sustainable utilization in daily life. Herein, a NiCoB based in-plane textile device with excellent electrochemical and mechanical performances is achieved via combining screen printing and electroless deposition strategies. The upper layer of NiCoB with a continuous micro-balls structure can effectively disperse the central stress under bent state, well protecting the bottom Ni coating. Thus, the two-layer structure ensures the electric and electrochemical stability even suffering a mechanical loading. At the same time, the NiCoB is capable of providing considerable energy storage performance with a high capacitance of 883.3 mF cm−2 under 5 mV s−1. Coupling with a synthesized ZIF-C negative material, the in-plane micro-supercapacitor (MSC) also exhibits great performances in both energy storage and mechanical stability. It can deliver a specific capacitance, a power density, and an energy density of 155.3 mF cm−2, 1.09 mW cm−2, and 42.27 μWh cm−2, respectively, while sustaining a 1000 bending cycle with little capacity decay. This flexible in-plane MSC textile can be a powerful candidate for future integrated smart garments and will provide some enlightenment in developing composited textile devices with perfect mechanical performance.

Fixture-free omnidirectional prestretching fabrication and integration of crumpled in-plane micro-supercapacitors.

Multidimensional folded structures with elasticity could provide spatial charge storage capability and shape adaptability for micro-supercapacitors (MSCs). Here, highly crumpled in-plane MSCs with superior conformality are fabricated in situ and integrated by a fixture-free omnidirectional elastic contraction strategy. Using carbon nanotube microelectrodes, a single crumpled MSC holds an ultrahigh volumetric capacitance of 9.3 F cm−3, and its total areal capacitance is 45 times greater than the initial state. Experimental and theoretical simulation methods indicate that strain-induced improvements of adsorption energy and conductance for crumpled microelectrodes are responsible for the prominent enhancement of electrochemical performance. With outstanding morphological randomicity, the integrated devices can serve as smart coatings in moving robots, withstanding extreme mechanical deformations. Notably, integration on a spherical surface is possible by using a spherical mask, in which a small area of the microdevice array (3.9 cm2) can produce a high output voltage of 100 V.

Combination of chemical foaming strategy and laser-induced graphene technology for enhanced paper-based microsupercapacitor

Laser-induced graphene (LIG) technology is qualified for manufacturing in-plane microsupercapacitors (MSCs) for its low cost and efficient fabrication. However, useable substrate and modification mechanism are mutual restricted for properties of materials. In this work, we creatively combine the chemical foaming strategy and laser-induced graphene technology based on commercial paper. Through a simple process, capacitance of assembled paper-based MSC is ∼350 times higher than control group without foaming and ∼7 times higher than device based on frequently-used polymer film. Specific areal capacitance and areal energy density reach up to 23.8 mF cm−2 and 2.64 μWh cm−2 respectively. This obvious capacitance enhancement is also accompanied by significantly reduced electrochemical impedance (almost two orders of magnitude smaller than unfoamed one) and excellent cycle performance (97% capacitance retention after 10000 cycles at high rates). It can be explained by distinct porous morphology, increased specific surface area (∼4 times higher than unfoamed material), changed N-doping type (increased pyridinic N) and improved product yield (∼2 times higher than control group) of the laser-induced foamed graphene (LIFG) material. The methodology proposed in this work paves a new avenue for modulating structures and components and improving electrode/electrolyte interface of carbon materials for high-performance energy storage devices.