High-performance Micro-supercapacitors Research Articles

Bioinspired Synaptic Branched Network within Quasi-Solid Polymer Electrolyte for High-Performance Microsupercapacitors.

The branched network-driven ion solvating quasi-solid polymer electrolytes (QSPEs) are prepared via one-step photochemical reaction. A poly(ethylene glycol diacrylate) (PEGDA) is combined with an ion-conducting solvate ionic liquid (SIL), where tetraglyme (TEGDME), which acts like interneuron in the human brain and creates branching network points, is mixed with EMIM-NTf2 and Li-NTf2 . The QSPE exhibits a unique gyrified morphology, inspired by the cortical surface of human brain, and features well-refined nano-scale ion channels. This human-mimicking method offers excellent ion transport capabilities through a synaptic branched network with high ionic conductivity (σDC ≈ 1.8 mS cm-1 at 298 K), high dielectric constant (εs ≈ 125 at 298 K), and strong ion solvation ability, in addition to superior mechanical flexibility. Furthermore, the interdigitated microsupercapacitors (MSCs) based on the QSPE present excellent electrochemical performance of high energy (E = 5.37 µWh cm-2 ) and power density (P = 2.2 mW cm-2 ), long-term cycle stability (≈94% retention after 48 000 cycles), and mechanical stability (>94% retention after continuous bending and compressing deformation). Moreover, these MSC devices have flame-retarding properties and operate effectively in air and water across a wide temperature range (275 to 370 K), offering a promising foundation for high-performance, stable next-generation all-solid-state energy storage devices.

3D-printed, high-energy-density, current collector-free flexible micro-supercapacitors based on CNT@V2O5 nanowires

Herein, we present current collector-free, high-performance micro-supercapacitors (MSCs) fabricated by 3D extrusion-based printing. To this end, we develop printable hybrid electrode inks by combining V2O5 nanowires (NWs) and carbon nanotubes (CNTs). The performance of the hybrid electrodes is optimized by rationally tailoring the V2O5 NW-to-CNT ratio. Owing to the high conductivity of the hybrid electrodes, the resulting MSCs could operate even without a current collector. Additionally, we improve the areal capacitance by increasing the mass loading per unit area through multiple printing in the vertical direction. The final multilayered MSCs exhibit outstanding energy-storage characteristics, including a high areal capacitance (18.98 mF/cm2 at 0.05 mA/cm2), a high energy density of 5.93 μWh/cm2 at a power density of 39.99 μW/cm2, excellent cycle stability (10,000 cycles), and reliable operation under mechanical deformation.

Enhancing energy storage performance in flexible all-solid-state laser-induced graphene-based microsupercapacitors through the addition of carbon black and Prussian blue

In this study, we present an efficient and scalable method for the stepwise modification of polyimide (PI)-based laser-induced graphene using environmentally friendly additives. The as-prepared composite materials were applied as flexible electrodes for high-performance all-solid-state microsupercapacitors (MSCs). The electrochemical deposition of carbon black (CB) microparticles and Prussian blue (PB) inorganic redox dye onto the laser-induced graphene electrode surface significantly enhanced the electrochemical performance of the devices. The areal capacitance of MSCs increased by 116 % after the addition of CB to the electrode composition, 201 % after the modification of the electrode surface with PB, and 325 % after incorporating both CB and PB (CB-PB). The exhibited capacitance values at an applied current density of 0.1 mA·cm−2 are equal to 27.6, 38.5 and 54.4 mF·cm−2 upon incorporating CB, PB and CB-PB, respectively. Furthermore, the use of a PVA/H2SO4 gel electrolyte led to a large stability electrochemical window of 3.0 V, resulting in an energy density as high as 68.1 μWh·cm−2 with a power density of 0.3 mW·cm−2 at 0.10 mA·cm−2. Additionally, the MSCs modified with CB-PB showed an excellent electrochemical stability, retaining over 95.8 % of their initial capacitance after 6000 galvanostatic charge-discharge cycles. Overall, this study presents a facile, convenient, and scalable approach for designing cost-effective and high-performance MSCs with a low-carbon footprint suitable for powering low-energy-consuming electronics.

A Biodegradable High-Performance Microsupercapacitor for Environmentally Friendly and Biocompatible Energy Storage.

Biodegradable and biocompatible microscale energy storage devices are very crucial for environmentally friendly microelectronics and implantable medical applications. Herein, a biodegradable and biocompatible microsupercapacitor (BB-MSC) with satisfying overall performance is realized via the combination of three-dimensional (3D) printing technique and biodegradable materials. Due to the 3D-interconnected structure of electrodes and elaborated design of electrolyte, the as-prepared BB-MSC exhibits superior overall performance than most of biodegradable devices, including a wide operation voltage of 1.8 V, high areal specific capacitance of 251 mF/cm2, good cycle stability, and favorable low-temperature resistance (-20 °C), demonstrative of reliability and practicality of our devices even in frosty environments. Importantly, the smooth degradation has been realized for the BB-MSC after being buried in natural soil for ∼90 days, and its implantation does not affect the healthy status of SD rats. Therefore, this work explores avenues for the design and construction of environmentally friendly and biocompatible microscale energy storage devices.

Laser-induced transient conversion of rhodochrosite/polyimide into multifunctional MnO2/graphene electrodes for energy storage applications

Laser-induced graphene (LIG) has been extensively investigated for electrochemical energy storage due to its easy synthesis and highly conductive nature. However, the limited charge accumulation in LIG usually leads to significantly low energy densities. In this work, we report a novel strategy to directly transform natural rhodochrosite into ultrafine manganese dioxide (MnO2) nanoparticles (NPs) in the polyimide (PI) substrate for high-performance micro-supercapacitors (MSCs) and lithium-ion batteries (LIBs) through a scalable and cost-effective laser processing method. Specifically, laser treatment on rhodochrosite/polyimide precursors induces the thermal explosion, which splits rhodochrosite (10 μm) into MnO2 NPs (12–16 nm) on the carbon matrix of LIG due to the sputtering effect. Benefiting from largely exposed active sites from the ultrafine MnO2 and the synergetic effect from highly conductive LIG, the MnO2/LIG MSCs show a high specific capacitance of 544.0 F g−1 (154.3 mF cm−2; 14.16 F cm−3) at 3 A/g and 82.1% capacitance retention after 10,000 cycles at 5A/g, in contrast to pure LIG (<100 F g−1). Moreover, the MnO2/LIG-based LIBs show the highest reversible discharge capacity of ∼1097 mAh g−1 at 0.2 A/g and ∼ 866.4 mAh g−1 at 1.0 A/g. This study opens a new route for synthesizing novel LIG-based composites from natural minerals.

Hexaazatriphenylene-doped MXene films for the high-performance micro-supercapacitors and wearable pressure sensor system

Two-dimensional MXene nanosheets have found extensive applications in portable electronic devices and flexible energy storage systems. However, the self-stacking effect caused by van der Waals forces severely restricts the rapid transport of electrolyte ions, thereby impacting the electrochemical performance. Here, nitrogen-doped MXene nanosheets (MXene-H) were obtained via surface modification of MXene with hexaazidotriphenylene (HAT) derivatives. The nitrogen atoms introduced between the layers act as pillars, widening the layer spacing and exposing more electrochemically active sites. By optimizing the doping ratio, the MXene-H micro-supercapacitor (MXene-H-MSC) exhibits outstanding electrochemical performance, with an area capacitance of 210.1 mF/cm2 and an energy density of 29.18 mWh/cm2, significantly surpassing that of previously reported MXene-based micro-supercapacitors. Moreover, the MXene-H-MSC demonstrates excellent cycling stability and flexibility, retaining 95% capacitance after 10,000 cycles, with no significant capacitance degradation observed in the CV curves tested at different angles. Furthermore, a micro-integrated system composed of the MXene-H-MSC and an MXene hydrogel pressure sensor in series can effectively respond to small changes in body movements, including speaking and finger flexing. This work provides potential guidance for research into the next generation of microelectronics.

Graphene/SiC composite porous electrodes for high-performance micro-supercapacitors

Micro-supercapacitor (MSC) electrodes prepared by chemical vapor deposition (CVD) possess high potential as on-chip integrated micro-power sources for future microdevices. In this study, porous graphene/SiC composite films are grown using laser CVD. A double-layer specific capacitance up to 219.3 mF/cm2 is achieved at 10 mV/s, which is 26 times higher than those of the electrodes prepared by CVD with the same energy storage mechanism reported in literatures. After 20000 charge-discharge cycles at room temperature (20 °C) and variable temperatures (0–60 °C), the electrode exhibits robust cycling stability with 99.9% and 109.6% capacitance retention, respectively. Subsequently, it is revealed that the abundance of graphene on the SiC porous skeleton plays a key role in promoting the capacitance enhancement. The strong structure of SiC as well as the strong adhesion between graphene and SiC guarantee the excellent cycling stability. Evidently, the preparation of graphene/SiC porous composite films as MSC electrodes is a highly promising route for fabricating high-performance and reliable on-chip power sources for future miniaturized devices.

Oil palm lignin-derived laser scribed graphene in neutral electrolyte for high-performance microsupercapacitor application

Lignin is a renewable natural resource that could be derived from oil palm empty fruit bunches. It has generated significant interest as a precursor in synthesizing graphene as anode and cathode material for supercapacitors. In this paper, we report the synthesis of 3D hierarchical Laser Scribed Graphene (LSG) on a flexible polyimide substrate from lignin extracted from empty fruit bunches (EFB) of oil palm for microsupercapacitor applications. The intensity and speed of the laser have been tuned to yield densely compacted oil palm lignin LSG at a laser power of 70% and a speed of 30% (OPL-LSG 7030). OPL-LSG 7030 possessed lower equivalent series resistance of 60.1 Ω and a larger crystalline size of ∼31 nm than the rest of the tested samples. It exhibited exceptional areal capacitance of 30.77 mFcm−2 at a current density of 0.08 mAcm−2, an energy density of 0.00176 mWhcm−2 and a power density of 0.25 mWcm−2 when using a unique neutral PAAS/K2SO4 gel electrolyte. It achieved excellent capacitance retention of 88.4% after 5000 charge/discharge cycles and remarkable mechanical stability of 95% after 400 bending cycles. Furthermore, electrochemical studies revealed the redox properties of readily available quinone/ hydroquinone in the oil palm lignin, which could be inherited in graphene electrodes through a feasible and affordable approach for flexible green energy storage applications.

Laser direct synthesis of Co/CoO modified graphene for high-performance microsupercapacitors

Graphene/CoO nanocomposites have excellent electrochemical performance and are extensively applied to microsupercapacitors (MSCs). Herein, we propose a simple and efficient method for laser direct writing on a graphene oxide/Co(CH3COO)2 precursor to process graphene/Co/CoO nanocomposite interdigital electrodes for MSCs. This work investigates the structural defects, crystal structure, sheet resistance, elemental composition, and bond characteristics of graphene/Co/CoO nanocomposites synthesized at different laser writing speeds. The specific capacitance, power density, and energy density of the prepared MSC based on PVA/H3PO4 electrolyte and graphene/Co/CoO interdigital electrodes reach 420.23 mF cm−2 (48.31 F cm−3), 1.97 mW cm−2 (226.43 mW cm−3), and 58.37 μWh cm−2 (6.71 mWh cm−3), respectively. Moreover, the Coulombic efficiency and capacitance retention rate of the prepared MSC after 10,000 cycles are 97.97% and 86.56%, respectively. The charge storage of the prepared MSC is mainly achieved through diffusion-controlled intercalation reactions. In addition, the prepared MSC shows good mechanical flexibility.

Boron and fluorine Co-doped laser-induced graphene towards high-performance micro-supercapacitors

Laser-induced graphene (LIG) has attracted extensive research as an electrode material for micro-supercapacitors (MSC). However, the low capacitive performance of LIG arising from both limited specific surface area and few active sites remains challenging. Herein, in situ doping of fluorine and boron atoms into laser-induced graphene was innovatively achieved via laser direct writing approach using boron-doped fluorinated polyimide (FB-PI) as the precursor. The porous fluorine and boron co-doped laser-induced graphene (FB-LIG) exhibits more active sites and improved wettability and significantly enhanced capacitive performance due to the synergistic effect of fluorine and boron co-doping. By tuning the weight ratio of boron to fluorine, the MSC utilizing FB-LIG as the electrode and poly(vinyl alcohol) (PVA)/H2SO4 as the gel electrolyte delivers a high areal capacitance of 49.81 mF/cm2 at a current density of 0.09 mA/cm2, 23 times higher that of MSC from commercial polyimide (PI)-based LIG, and 3 times that of MSC from fluorinated PI-based LIG. In addition, MSCs from FB-LIG possess excellent mechanical stability and flexibility, rendering them promising for flexible wearable microelectronics.

Laser-induced graphene electrodes scribed onto novel carbon black-doped polyethersulfone membranes for flexible high-performance microsupercapacitors

A facile and expandable methodology was successfully developed to fabricate laser-induced graphene from novel pristine aminated polyethersulfone (amPES) membranes. The as-prepared materials were applied as flexible electrodes for microsupercapacitors. The doping of amPES membranes with various weight percentages of carbon black (CB) microparticles was then performed to improve their energy storage performance. The lasing process allowed the formation of sulfur- and nitrogen-codoped graphene electrodes. The effect of electrolyte on the electrochemical performance of as-prepared electrodes was investigated and the specific capacitance was significantly enhanced in 0.5 M HClO4. Remarkably, the highest areal capacitance of 47.3 mF·cm−2 was achieved at a current density of 0.25 mA·cm−2. This capacitance is approximately 12.3 times higher than the average value for commonly used polyimide membranes. Furthermore, the energy and power densities were as high as 9.46 µWh·cm−2 and 0.3 mW·cm−2 at 0.25 mA·cm−2, respectively. The galvanostatic charge–discharge experiments confirmed the excellent performance and stability of amPES membranes during 5,000 cycles, where more than 100% of capacitance retention was achieved and the coulombic efficiency was improved up to 96.67%. Consequently, the fabricated CB-doped PES membranes offer several advantages including low carbon fingerprint, cost-effectiveness, high electrochemical performance and potential applications in wearable electronic systems.

Large Area Millisecond Preparation of High-Quality, Few-Layer Graphene Films on Arbitrary Substrates via Xenon Flash Lamp Photothermal Pyrolysis and Their Application for High-Performance Micro-supercapacitors.

We report a method for fast, efficient, and scalable preparation of high-quality, large area, few-layer graphene films on arbitrary substrates via high-intensity pulsed xenon flash lamp photothermal pyrolysis of thin precursor films at ambient conditions in millisecond time frames. The precursors comprised poly(2,2-bis(3,4-dihydro-3-phenyl-1,3-benzoxazine)), and cyclized polyacrylonitrile and possess significant absorption cross section within the bandwidth of the emission spectrum of a xenon flash lamp. By localizing light absorption to the precursor films, the process enabled the preparation of few-layer graphene films on any substrate, including thermally sensitive substrates without the need for any catalytic substrate as in chemical vapor deposition-based approaches or conductive electrodes as in electrochemical method-based approaches. The extent of conversion of the precursor films to graphene was strongly dependent on pulse energy and the local temperature achieved due to photothermal effect, which were controlled via pulse power modulation; it also depended on structural properties of the precursor and to a lesser extent on the substrate. The cPAN showed a higher efficiency for conversion to graphene, as confirmed by Raman spectra (ID/IG ∼ 0.3), and sheet resistance of 0.1 Ω cm. To demonstrate the utility of the process, graphene film electrodes prepared photothermally on carbon fiber current collector were used for the fabrication of micro-supercapacitors with a very high areal supercapacitance of 3.5 mF/cm2. Subsequent deposition of manganese oxide onto the fabricated electrodes significantly increased the energy storage capability of the supercapacitor, yielding a device with exceptionally high capacitance of 80 F/g at 1 mA current, good rate capability, and long cycle life.

High-Ionic-Conductivity Sodium-Based Ionic Gel Polymer Electrolyte for High-Performance and Ultrastable Microsupercapacitors

Due to the lower cost and greater natural abundance of the sodium element on the earth than those of the lithium element, sodium-based ionic gel polymer electrolytes (IGPEs) are becoming a more cost-effective and popular material choice for portable and stationary energy solutions. The sodium-based IGPEs, however, appeared relatively inferior to their lithium-based counterparts for use in high-performance microsupercapacitors in terms of ionic conductivity and electrochemical stability. To tackle these issues, poly(ethylene glycol) diacrylate (PEGDA) with fast polymerization to build a polymer matrix and sodium perchlorate (NaClO4) with high chemical stability and high thermal stability are employed to generate free ions for an ionic conducting phase with the support of tetramethylene glycol ether (G4) and 1-ethyl-3-methylimidazolium bis(triflouromethylsulfonyl)imide (EMIM-TFSI). It was found that the ionic conductivity (σdc) of this sodium-based IGPE reaches up to 0.54 mS/cm at room temperature. To manifest a high-conductivity sodium-based IGPE (SIGPE), a microsupercapacitor (MSC) with an area of 5 mm2 is designed and fabricated on an interdigital reduced graphene oxide electrode. This MSC demonstrates prominent performance with a high power density of ∼2500 W/kg and a maximum energy density of ∼0.7 Wh/kg. Furthermore, after 20,000 cycles at an operating potential window from 0.0 to 1.0 V, it retains approximately 98.9% capacitance. An MSC array in 3 series × 3 parallels (3S × 3P) was successfully designed as a power source for a basic circuit with an LED. Therefore, we believe that our sodium-based IGPE microsupercapacitor holds its promising role as a solid-state energy source for high-performance and high-stability energy solutions.

Role of the electrode-edge in optically sensitive three-dimensional carbon foam-MoS2based high-performance micro-supercapacitors

Developing high-performance micro-supercapacitors in a limited footprint area is important for miniaturized electronics, where enhancement in energy storage per unit area is critical.

Three dimensional high-performance micro-supercapacitors with switchable high power density and high energy density.

In the field of microscale energy storage, the fabrication of micro-supercapacitors (MSCs) with high power density and high energy density has always been a focus of research. In this work, laser-induced porous graphene and chemically deposited manganese dioxide nanoparticles are used as electrode materials, and a switchable MSC with two energy storage principles is obtained by designing symmetric interdigitated and square electrode structures. The aim is to overcome the preparation challenge of supercapacitors with high energy density and high power density by switching between two modes. In this MSC, the energy density of the high energy density mode (5.89 μW h cm-2) is 3.36 times that of the high power density mode (1.75 μW h cm-2), while the power density of the high power density mode (43.06 μW cm-2) is 1.44 times that of the high energy density mode (29.96 μW cm-2). In addition, under the drive of five serially connected MSCs, 27 LED lights can be continuously lit for 5 minutes. Therefore, this work provides a facile and novel method for the development of MSCs with high power density and high energy density, suggesting a great practical application value in the development of MSCs.

MXene decorated 3D-printed carbon black-based electrodes for solid-state micro-supercapacitors

Three-dimensional (3D) printing offers a unique approach to fabricating free-standing and complex structured electrodes for high-performance micro-supercapacitors (MSCs).

Controllable synthesis of 2D mesoporous nitrogen-doped carbon/graphene nanosheets for high-performance micro-supercapacitors

Controllable synthesis of 2D mesoporous nitrogen-doped carbon/graphene nanosheets for high-performance micro-supercapacitors

High-performance environmental adaptive microsupercapacitors from multifunctional hydrogel via modulating ionic hydration and hydrogen bonds

The advance of microelectronic systems requires their energy power microsupercapacitors (MSCs) possessing environmental adaptability beyond the high energy density. The electrolyte in MSCs plays a crucial role in satisfying the above requirements. In this work, we experimentally demonstrate the hydrogel electrolyte with multifunctions, including ultralow phase-transition temperature of -103.8 °C, 2.80 V electrochemical window, superior anti-dehydration and rapid self-healing ability, via modulating its ionic hydration and hydrogen bonds. It is used to build graphene-based MSCs, which show promising energy density of 41.56 µWh cm−2, super-wide working temperature range from -60 to 100 °C, exciting self-regeneration ability after deep dehydration and self-healing ability under severe physical damage. The MSCs meet the requirement of advanced microelectronic systems. The strategy developed here paves a way towards high-performance MSCs in harsh environment.

Sputtered (Fe,Mn)3O4 Spinel Oxide Thin Films for Micro-Supercapacitor

The scaling up of wireless operating microelectronics for upcoming Internet of Things (IoT) applications demands high-performance micro-supercapacitors (MSCs) with corresponding high-energy and power capabilities. Indeed, this necessitates the quest for MSC’s electrode materials capable of delivering high energy density at high charge/discharge rates. Many multicationic oxides, such as spinel manganese-iron compounds, demonstrate good pseudocapacitive properties as positive electrodes in conventional supercapacitors. However, fulfilling the required fabrication techniques is a challenge for their applications in MSCs. Hence, this study, for the first time, demonstrates the successful deposition of spinel Mn-Fe thin films on a functional platinum-based current collector. The deposition is achieved in a reactive oxygen environment via reactive DC magnetron sputtering techniques and subsequently annealed ex situ at 600 °C in a nitrogen environment. The electrochemical signature in neutral 1 M Na2SO4 aqueous electrolyte is comparable to those reported for spinel type Mn-Fe bulk counterparts. The areal capacitance at 10 mV.s−1 is 15.5 mF.cm−2 for 1 μm thick film, exhibiting excellent coulombic efficiency (close to 100%) and long-term cycle stability after 10,000 cycles. Thus, the synthesis of the multicationic pseudocapacitive oxides via compatible microelectronic deposition methods has set a prospective path to achieve very high-performance MSCs for future IoT applications.

Smart wearable band-aid integrated with high-performance micro-supercapacitor, humidity and pressure sensor for multifunctional monitoring

Band-aids, which possess breathable woven fabric and a compressible cotton pad, can be a potential substrate for smart wearable electronics. However, integrating energy storage modules and multiple functions into commercial band-aids through a simple and practical method is still a huge challenge. In this work, we design a multifunctional intelligent wearable band-aid, which integrates the high-performance micro-supercapacitor (MSC) with humidity and pressure sensors, through a facile laser-scribing and single-wall carbon nanotubes (CNT) drop-casting strategy. As a proof of concept, the fabricated laser-induced sulfur-doped porous graphene-based MSC on the band-aid surface offers an excellent areal capacitance of 68.6 mF cm−2 and good cyclic stability. Also, the designed humidity sensor has a fast and reversible real-time response and a wide relative humidity (RH) sensing range (11–97% RH). Remarkably, the obtained capacitive pressure sensor has a high sensitivity of 25.15 kPa−1, an ultra-broad linear range (0 ∼ 300 kPa) and a low limit of detection of 2.92 Pa. This proposed band-aid based multifunctional integrated system paves a new avenue for the development of smart wearable and flexible electronics.