Ultrahigh-Areal Capacitance Flexible Supercapacitors Based on Laser Assisted Construction of Hierarchical Aligned Carbon Nanotubes

Electrochemical energy storage is a key technology for a clean and sustainable energy supply. In this respect, supercapacitors (SC) have recently received considerable attention due to their excellent performance, including high-power density and long-cycle life. However, the poor binding strength between the active materials and substrate, the low active material loading, and small specific capacitance hinder the overall performance improvement of the device. In this study, an ultrahigh-areal capacitance flexible SC based on the Al micro grid-based hierarchical vertically aligned carbon nanotubes (VACNTs) is studied. Interestingly, the Al micro grid-based VACNTs exhibit ultrahigh loading (13 mg cm⁻²), and the as-fabricated VACNTs electrode display outstanding electrochemical performance, including an impressive areal capacitance of 1,300 mF cm⁻² at the current density of 13 mA cm⁻² and excellent stability with a retention ratio of 90% after 20,000 cycles at the current density of 130 mA cm⁻². Furthermore, the hierarchical VACNT electrodes show excellent mechanical flexibility when assembled into quasi-solid-state SC using Na₂SO₄-PVA gel as the electrolyte. The capacitance of this device is hardly changed bending different angles, even 180°. This study demonstrates the tremendous potential of Al micro grid-based hierarchical VACNTs as electrodes for high-performance flexible and wearable energy storage devices.     

Wearable Biosupercapacitor: Harvesting and Storing Energy from Sweat

This work demonstrates the first example of sweat-based wearable and stretchable biosupercapacitors (BSCs), capable of generating high-power pulses from human activity. The all-printed, dual-functional, conformal BSC platform can harvest and store energy from sweat lactate. By integrating energy harvesting and storage functionalities on the same footprint of a single epidermal device, the new wearable energy system can deliver high-power pulses and be rapidly self-charged by bioenergy conversion of sweat lactate generated from human activity while simplifying the design and fabrication. The mechanical robustness and conformability of the device are realized through island-bridge patterns and strain-enduring inks. The enhanced capacitance of the BSC is realized by the synergistic effect of carbon nanotube ink with electrodeposited polypyrrole on the anode and of porous cauliflower-like platinum on the cathode. In the presence of lactate, the BSC shows high power in pulsed output and stable cycling performance. Furthermore, the wearable device can store energy and deliver high-power pulses long after the perspiration stopped. The self-charging hybrid wearable device obtained high power of 1.7 mW cm⁻² in vitro, and 343 µW cm⁻² on the body during exercise, suggesting considerable potential as a power source for the next generation of wearable electronics.     

Biomass-Derived Inks with Tailored Pteridine Derivatives for Sustainable Printed Micro-Supercapacitors

Using biological redox compounds holds great potential in designing sustainable energy storage systems, but it is essential for structure optimization of biological redox centers and in-depth studies regarding their underlying energy storage mechanisms. Herein, a molecular simplification strategy is proposed to tailor the redox unit of pteridine derivatives, an essential component of ubiquitous electron transfer proteins in nature. The tailored pteridine derivatives can be combined with biomass holey graphene (BHG) to fabricate an ink with a micrometer-scale resolution for printing flexible electrodes for micro-supercapacitor (MSCs). The reversible tautomerism of pteridine derivatives from alloxazinic to isoalloxazinic structure is first unveiled in supercapacitors. Through molecular tailoring, printed MSC electrodes using pteridine derivatives/BHG ink demonstrate excellent charge storage, outstanding areal capacitance (95.3 mF cm⁻² at 0.1 mA cm⁻²), energy density (16.3 µWh cm⁻²), power density (208 µW cm⁻²), long-term cycling performance (90.5% retention after 10 000 cycles), easy integration, and exceptional flexibility (maintaining capacitance at various bending states). The non-covalent interaction of tailored pteridine molecules with redox centers and biomass porous graphene suggests a mature screen-printing technology for fabricating a sustainable energy storage system with a rational MSC configuration.     

Flexible and Wire‐Shaped Micro‐Supercapacitor Based on Ni(OH)2‐Nanowire and Ordered Mesoporous Carbon Electrodes

Portable and multifunctional electronic devices are developing in the trend of being small, flexible, roll‐up, and even wearable, which asks us to develop flexible and micro‐sized energy conversion/storage devices. Here, the high performance of a flexible, wire‐shaped, and solid‐state micro‐supercapacitor, which is prepared by twisting a Ni(OH)2‐nanowire fiber‐electrode and an ordered mesoporous carbon fiber‐electrode together with a polymer electrolyte, is demonstrated. This micro‐supercapacitor displays a high specific capacitance of 6.67 mF cm^–1 (or 35.67 mF cm^–2) and a high specific energy density of 0.01 mWh cm^–2 (or 2.16 mWh cm^–3), which are about 10–100 times higher than previous reports. Furthermore, its capacitance retention is 70% over 10 000 cycles, indicating perfect cyclic ability. Two wire‐shaped micro‐supercapacitors (0.6 mm in diameter, ≈3 cm in length) in series can successfully operate a red light‐emitting‐diode, indicating promising practical application. Furthermore, synchrotron radiation X‐ray computed microtomo­graphy technology is employed to investigate inner structure of the micro‐device, confirming its solid‐state characteristic. This micro‐supercapacitor may bring new design opportunities of device configuration for energy‐storage devices in the future wearable electronic area.     

Interface Engineering of Biomass-Derived Carbon used as Ultrahigh-Energy-Density and Practical Mass-Loading Supercapacitor Electrodes

The development of flexible electrodes with high mass loading and efficient electron/ion transport is of great significance but still remains the challenge of innovating suitable electrode structures for high energy density application. Herein, for the first time, lignosulfonate-derived N/S-co-doped graphene-like carbon is in situ formed within an interface engineered cellulose textile through a sacrificial template method. Both experimental and theoretical calculations disclose that the formed pomegranate-like structure with continuous conductive pathways and porous characteristics allows sufficient ion/electron transport throughout the entire structures. As a result, the obtained flexible electrode delivers a remarkable integrated capacitance of 6534 mF cm⁻² (335.1 F g⁻¹) and a superior stability at an industrially applicable mass loading of 19.5 mg cm⁻². A pseudocapacitive cathode with ultrahigh capacitance of 7000 mF cm⁻² can also be obtained based on the same electrode structure engineering. The as-assembled asymmetric supercapacitor achieves a high areal capacitance of 3625 mF cm⁻², and a maximum energy density of 1.06 mWh cm⁻², outperforms most of other reported high-loading supercapacitors. This synthesis method and structural engineering strategy can provide materials design concepts and a wide range of applications in the fields of energy storage beyond supercapacitors.     

Nature-Inspired Interconnected Macro/Meso/Micro-Porous MXene Electrode

The geometric multiplication development of MXene has promoted it to become a star material in numerous applications including, but not limited to, energy storage. It is found that pore structure modulation engineering can improve the inherent properties of MXene, in turn significantly enhancing its electrochemical performance. However, most of the current works have focused on exploring the structure-effective relationships of the single-scale pore structure regulation of MXene. Inspired by Murray's law from nature where a highly graded structure of the organisms is discovered and used to achieve effective diffusion and maximize mass transfer, a hierarchically interconnected porous MXene electrode across micro-meso-macroporous is constructed. This MXene-based electrode provides large amounts of active sites while greatly shortening the ion diffusion channel. Finally, the zinc ion microcapacitor based on this MXene electrode exhibits an ultrahigh area-specific capacitance up to 410 mF cm⁻² and an energy density up to 103 µWh cm⁻² at a power density of 2100 µW cm⁻². The areal energy density outperforms the currently reported zinc ion microcapacitors. This study supports an effective strategy for electrode materials (including but not limited to MXene) to achieve ultra-short ion diffusion channels and maximum transport efficiency for next-generation high-performance energy storage.     

Regulating Oxygen Substituents with Optimized Redox Activity in Chemically Reduced Graphene Oxide for Aqueous Zn-Ion Hybrid Capacitor

Functionalizing carbon cathode surfaces with oxygen functional groups is an effective way to simultaneously tailor the fundamental properties and customize the electrochemical properties of aqueous Zn-ion hybrid capacitors. In this work, the oxygen functional groups of chemically reduced graphene oxide (rGO) are systematically regulated via a series of reductants and varied experimental conductions. Carboxyl and carbonyl have been proven to significantly enhance the aqueous electrolyte wettability, Zn-ion chemical adsorption, and pseudocapacitive redox activity by experimental study and computational analysis. The rGO cathode produced through hydrogen peroxide assisted hydrothermal reduction exhibits a specific capacitance of 277 F g⁻¹ in 1 m ZnSO₄ after optimization of surface oxygen functional groups. In addition, a quasi-solid-state flexible Zn-ion hybrid capacitor (ZHC) with a polyacrylamide gel electrolyte and a high loading mass of 5.1 mg cm⁻² are assembled. The as-prepared quasi-solid state ZHC can offer a superior areal capacitance of 1257 mF cm⁻² and distinguished areal energy density of 342 µW h cm⁻². The significant enhancement of redox activity and Zn-ion storage capability by regulating the oxygen functional groups can shed light on the promotion of electrochemical charge storage properties even beyond protic electrolyte systems.     

Anisotropic ZnS Nanoclusters/Ordered Macro-Microporous Carbon Superstructure for Fibrous Supercapacitor toward Commercial-Level Energy Density

Fibrous supercapacitor (FSC) is of great attention in wearable electronics, but is challenged by low energy density, owing to disordered diffusion pathway and sluggish redox kinetics. Herein, using micro-reaction strategy, an anisotropic superstructure is developed by in situ anchoring ultrafine zinc sulfine (ZnS) nanoclusters on conductively ordered macro-microporous carbon skeleton via interfacial C S Zn bonds (ZnS/SOM-C). The anisotropic superstructure affords 3D ordered macro-microporous pathways, large accessible surfaces, and highly dispersed active sites, which exhibit enhanced electrolyte mass diffusion, rapid interfacial charge transfer, and large faradaic ions storage (capacitance of 1158 F g⁻¹ in KOH aqueous solution). By microfluidic spinning, the ZnS/SOM-C is further assembled into fibrous electrode of FSC that delivers high capacitance (791 F g⁻¹), commercial-level energy density (172 mWh g⁻¹), and durable stability. As a result, the FSC can realize wearable self-powered applications (e.g., self-cleaning ventilatory mask, smartwatch, and display), exhibiting the superiority in new energy and wearable industry.     

Scalable Production of Graphene Inks via Wet‐Jet Milling Exfoliation for Screen‐Printed Micro‐Supercapacitors

The miniaturization of energy storage units is pivotal for the development of next‐generation portable electronic devices. Micro‐supercapacitors (MSCs) hold great potential to work as on‐chip micro‐power sources and energy storage units complementing batteries and energy harvester systems. Scalable production of supercapacitor materials with cost‐effective and high‐throughput processing methods is crucial for the widespread application of MSCs. Here, wet‐jet milling exfoliation of graphite is reported to scale up the production of graphene as a supercapacitor material. The formulation of aqueous/alcohol‐based graphene inks allows metal‐free, flexible MSCs to be screen‐printed. These MSCs exhibit areal capacitance (C_areal) values up to 1.324 mF cm^?2 (5.296 mF cm^?2 for a single electrode), corresponding to an outstanding volumetric capacitance (C_vol) of 0.490 F cm^?3 (1.961 F cm^?3 for a single electrode). The screen‐printed MSCs can operate up to a power density above 20 mW cm^?2 at an energy density of 0.064 µWh cm^?2. The devices exhibit excellent cycling stability over charge–discharge cycling (10 000 cycles), bending cycling (100 cycles at a bending radius of 1 cm) and folding (up to angles of 180°). Moreover, ethylene vinyl acetate‐encapsulated MSCs retain their electrochemical properties after a home‐laundry cycle, providing waterproof and washable properties for prospective application in wearable electronics.     

A Flexible and Safe Planar Zinc-Ion Micro-Battery with Ultrahigh Energy Density Enabled by Interfacial Engineering for Wearable Sensing Systems

Aqueous zinc-ion micro-batteries (ZIMBs) have attracted considerable attention owing to their reliable safety, low cost, and great potential for wearable devices. However, current ZIMBs still suffer from various critical issues, including short cycle life, poor mechanical stability, and inadequate energy density. Herein, the fabrication of flexible planar ZIMBs with ultrahigh energy density by interfacial engineering in the screen-printing process based on high-performance MnO₂-based cathode materials is reported. The Ce-doped MnO₂ (Ce-MnO₂) exhibits significantly enhanced capacity (389.3 mAh g⁻¹), considerable rate capability and admirable cycling stability than that of the pure MnO₂. Importantly, the fabrication of micro-electrodes with ultrahigh mass loading of Ce-MnO₂ (24.12 mg cm⁻²) and good mechanical stability is achieved through optimizing the interfacial bonding between different printed layers. The fabricated planar ZIMBs achieve a record high capacity (7.21 mAh cm⁻² or 497.31 mAh cm⁻³) and energy density (8.43 mWh cm⁻² or 573.45 mWh cm⁻³), as well as excellent flexibility. Besides, a wearable self-powered sensing system for environmental monitoring is further demonstrated by integrating the planar ZIMBs with flexible solar cells and a multifunctional sensor array. This work sheds light on the development of high-performance planar ZIMBs for future self-powered and eco-friendly smart wearable electronics.     

Layered Double Hydroxide with Interlayer Quantum Dots and Laminate Defects for High-Performance Supercapacitor

Owing to the flexible adjustability of laminates, layered double hydroxides (LDHs) can achieve enhanced conductivity and capacitance. However, the regulation of interlayer activity is a great challenge because of the unconquerable charge repulsion between laminates. Herein, a dual-activity design of LDHs is uniquely realized, including laminate defects and interlayer ZnS quantum dots (QDs). Via pre-embedding Zn2+ and controllable vulcanization, ZnS-QDs interpenetrate between CuCo-LDH layers, exposing abundant active sites and widening the layer spacing. Meanwhile, sulfur replaces part of the oxygen on the laminates to form rich oxygen vacancies (CuCo-LDH-S), which does not damage the layered spatial structure and ensures the fast ions/electron transport. Theoretical calculations indicate that the new active centers exhibit higher charge density as compared to CuCo-LDH. Moreover, the copper foam directly provides copper source to ensure that CuCo-LDH-S/ZnS-QDs present a 3D self-supporting structure with ultrastability. Hence, it delivers an ultrahigh capacitance of 7.82 F cm⁻² at 2 mA cm⁻² and 4.43 F cm⁻² at 20 mA cm⁻². The hybrid supercapacitors display an outstanding energy density of 299 µWh cm⁻² at power density of 1600 µW cm⁻², with outstanding capacitance retention of 102.3% and coulomb efficiency of 96.2% after 10 000 cycles.     

Flexible Sodium‐Ion Pseudocapacitors Based on 3D Na2Ti3O7 Nanosheet Arrays/Carbon Textiles Anodes

Flexible energy storage devices are critical components for emerging flexible and wearable electronics. Improving the electrochemical performance of flexible energy storage devices depends largely on development of novel electrode architectures and new systems. Here, a new class of flexible energy storage device called flexible sodium‐ion pseudocapacitors is developed based on 3D‐flexible Na₂Ti₃O₇ nanosheet arrays/carbon textiles (NTO/CT) as anode and flexible reduced graphene oxide film (GFs) as cathode without metal current collectors or conducting additives. The NTO/CT anode with advanced electrode architectures is fabricated by directly growing Na₂Ti₃O₇ nanosheet arrays on carbon textiles with robust adhesion through a simple hydrothermal process. The flexible GF//NTO/CT configuration achieves a high energy density of 55 Wh kg^?1 and high power density of 3000 W kg^?1. Taking the fully packaged flexible sodium‐ion pseudocapacitors into consideration, the maximum practical volumetric energy density and power density reach up to 1.3 mWh cm^?3 and 70 mW cm^?3, respectively. In addition, the flexible GF//NTO/CT device demonstrates a stable electrochemical performances with almost 100% capacitance retention under harsh mechanical deformation.     

A Low‐Cost,Self‐Standing NiCo2O4@CNT/CNT Multilayer Electrode for Flexible Asymmetric Solid‐State Supercapacitors

The demand for a new generation of flexible, portable, and high‐capacity power sources increases rapidly with the development of advanced wearable electronic devices. Here we report a simple process for large‐scale fabrication of self‐standing composite film electrodes composed of NiCo₂O₄@carbon nanotube (CNT) for supercapacitors. Among all composite electrodes prepared, the one fired in air displays the best electrochemical behavior, achieving a specific capacitance of 1,590 F g^?1 at 0.5 A g^?1 while maintaining excellent stability. The NiCo₂O₄@CNT/CNT film electrodes are fabricated via stacking NiCo₂O₄@CNT and CNT alternately through vacuum filtration. Lightweight, flexible, and self‐standing film electrodes (≈24.3 µm thick) exhibit high volumetric capacitance of 873 F cm^?3 (with an areal mass of 2.5 mg cm^?2) at 0.5 A g^?1. An all‐solid‐state asymmetric supercapacitor consists of a composite film electrode and a treated carbon cloth electrode has not only high energy density (≈27.6 Wh kg^?1) at 0.55 kW kg^?1 (including the weight of the two electrodes) but also excellent cycling stability (retaining ≈95% of the initial capacitance after 5000 cycles), demonstrating the potential for practical application in wearable devices.     

Alternative-Ultrathin Assembling of Exfoliated Manganese Dioxide and Nitrogen-Doped Carbon Layers for High-Mass-Loading Supercapacitors with Outstanding Capacitance and Impressive Rate Capability

Manganese dioxide (MnO₂) materials have received much attention as promising pseudocapacitive materials owing to their high theoretical capacitance and natural abundance. Unfortunately, the charge storage performance of MnO₂ is usually limited to commercially available mass loading electrodes because of the significantly lower electron and ion migration kinetics in thick electrodes. Here, an alternatively assembled 2D layered material consisting of exfoliated MnO₂ nanosheets and nitrogen-doped carbon layers for ultrahigh-mass-loading supercapacitors without sacrificing energy storage performance is reported. Layered birnessite-type MnO₂ is efficiently exfoliated and intercalated by a carbon precursor of dopamine using a fluid dynamic-induced process, resulting in MnO₂/nitrogen-doped carbon (MnO₂/C) materials after self-polymerization and carbonization. The alternatively stacked and interlayer-expanded structure of MnO₂/C enables fast and efficient electron and ion transfer in a thick electrode. The resulting MnO₂/C electrode shows outstanding electrochemical performance at an ultrahigh mass loading of 19.7 mg cm⁻², high gravimetric and areal capacitances of 480.3 F g⁻¹ and 9.4 F cm⁻² at 0.5 mA cm⁻², and rapid charge/discharge capability of 70% capacitance retention at 40 mA cm⁻². Furthermore, asymmetric supercapacitor based on high-mass-loading MnO₂/C can deliver an extremely high energy of 64.2 Wh kg⁻¹ at a power density of 18.8 W kg⁻¹ in an aqueous electrolyte.     

Multifunctional Carbon Felt Electrode with N-Rich Defects Enables a Long-Cycle Zinc-Bromine Flow Battery with Ultrahigh Power Density

Zinc-bromine flow batteries (ZBFBs) are regarded as one of the most promising technologies for energy storage owing to high energy density and low cost. However, the sluggish reaction kinetics of Br₂/Br⁻ couples and zinc dendrite issue lead to low power density and poor cycle stability. Herein, a multifunctional carbon felt-based electrode (NTCF) with N-rich defects is fabricated for ZBFBs. The defects with abundant N-containing groups on carbon fibers of NTCF provide high catalytic activity on Br₂/Br⁻ reactions. Simultaneously, the lower energy barrier of N-rich defects to adsorb zinc atoms, and more deposition sites on NTCF induce more uniform zinc deposition. Thus, a ZBFB using NTCF as both the anode and cathode can stably operate at an unprecedentedly high current density of 180 mA cm⁻² with a coulombic efficiency of 97.25%. Moreover, a long cycle life of over 140 cycles with a coulombic efficiency of 98.93% for a Zn symmetric flow battery at 80 mA cm⁻² is achieved under a high areal capacity of 40 mAh cm⁻². This current density and areal capacity are by far the highest values ever reported for Zn symmetry flow batteries. Therefore, this work provides an available approach to improve the power density and cycle life of ZBFBs.     

3D Printing-Directed Synergistic Design of High-Performance Zinc-Ion Hybrid Capacitors and Nanogenerators for All-In-One Self-Powered Energy Wristband

Advanced wearable self-powered energy systems that simultaneously achieve energy harvesting and energy storage offer exciting opportunities for flexible electronics, information communication, and even intelligent environmental monitoring. However, building and integrating synergistic energy storage from energy harvester unit into a single power source is highly challenging. Herein, a unique 3D printing-directed synergistic design of high-performance zinc-ion hybrid capacitors (ZIHCs) and triboelectric nanogenerators (TENGs) is proposed for the all-in-one self-powered wearable energy wristband. With advanced ink design, high-performance flexible ZIHCs are built up as the excellent energy storage unit with remarkable electrochemical behaviors and synergistic matching from TENGs. An exceptional device capacitance of 239.0 mF cm⁻², moderate potential window, high-rate capability, robust cycling stability, and excellent flexibility are achieved. Intrinsic charge storage process is also revealed, further demonstrating the outstanding electrochemical stability of the in-plane flexible ZIHCs. Moreover, using 3D printing-directed synergistic design, an advanced all-in-one self-powered energy wristband is developed, where an efficient harvesting of body vibration/movement energy and a reliable storage of harvested energy are simultaneously realized, representing a substantial step toward future practical applications in portable and wearable electronics.     

Aqueous Ammonium-Ion Supercapacitors with Unprecedented Energy Density and Stability Enabled by Oxygen Vacancy-Enriched MoO3@C

The use of non-metal charge carriers such as ammonium (NH₄⁺) in electrochemical energy storage devices offers advantages in terms of weight, element abundance, and compatibility with aqueous electrolytes. However, the development of suitable electrodes for such carriers lags behind other technologies. Herein, we present a high-performance anode material for ammonium-ion supercapacitors based on a MoO₃/carbon (MoO₃@C) composite. The NH₄⁺ storage performance of such composites and their practical application prospects are evaluated both in a three-electrode configuration and as symmetric supercapacitors. The optimized material reaches an unprecedented specific capacitance of 473 F·g⁻¹ (158 mAh·g⁻¹; 1592 mF·cm⁻²) at a current density of 1 A·g⁻¹, and 92.7% capacitance retention after 5000 cycles in a three-electrode set-up. This outstanding performance is related to the presence of oxygen vacancies that enhance the composites’ ionic/electronic transportation and electrochemical reaction site, while at the same time facilitating the formation of hydrogen bonds between NH₄⁺ and the host material. Using the optimized composite, symmetric supercapacitors based on an (NH₄)₂SO₄ gel electrolyte are fabricated and demonstrated to provide unmatched energy densities above 78 Wh·kg⁻¹ at a power density of 929 W·kg⁻¹. Besides, such devices are characterized by extraordinary capacitance retention of 97.6% after 10,000 cycles.     

Engineering MoS2 Nanosheets on Spindle‐Like α‐Fe2O3 as High‐Performance Core–Shell Pseudocapacitive Anodes for Fiber‐Shaped Aqueous Lithium‐Ion Capacitors

Fiber‐shaped aqueous lithium‐ion capacitors (FALICs) featured with high energy and power densities together with outstanding safety characteristics are emerging as promising electrochemical energy‐storage devices for future portable and wearable electronics. However, the lack of high‐capacitance fibrous anodes is a major bottleneck to achieve high performance FALICs. Here, hierarchical MoS₂@α‐Fe₂O₃ core–shell heterostructures consisting of spindle‐shaped α‐Fe₂O₃ cores and MoS₂ nanosheet shells on a carbon nanotube fiber (CNTF) are successfully fabricated. Originating from the unique core/shell architecture and prominent synergetic effects for multi‐components, the resulting MoS₂@α‐Fe₂O₃/CNTF anode delivers a remarkable specific capacitance of 2077.5 mF cm^?2 (554.0 F cm^?3) at 2 mA cm^?2, substantially outperforming most of the previously reported fibrous anode materials. Further density functional theory calculations reveal that the MoS₂@α‐Fe₂O₃ nano‐heterostructure possesses better electrical conductivity and stronger adsorption energy of Li⁺ than those of the individual MoS₂ and α‐Fe₂O₃. By paring with the self‐standing LiCoO₂/CNTF battery‐type cathode, a prototype quasi‐solid‐state FALIC with a maximum operating voltage of 2.0 V is constructed, achieving impressive specific capacitance (253.1 mF cm^?2) and admirable energy density (39.6 mWh cm^?3). Additionally, the newly developed FALICs can be woven into the flexible textile to power wearable electronics. This work presents a novel effective strategy to design high‐performance anode materials for next‐generation wearable ALICs.     

Polypyrrole/reduced graphene oxide coated fabric electrodes for supercapacitor application

Flexible and wearable energy storage devices are strongly demanded to power smart textiles. Herein, reduced graphene oxide (RGO) and polypyrrole (PPy) were deposited on cotton fabric via thermal reduction of GO and chemical polymerization of pyrrole to prepare textile-based electrodes for supercapacitor application. The obtained PPy–RGO-fabric retained good flexibility of textile and was highly conductive, with the conductivity of 1.2 S cm⁻¹. The PPy–RGO-fabric supercapacitor showed a specific capacitance of 336 F g⁻¹ and an energy density of 21.1 Wh kg⁻¹ at a current density of 0.6 mA cm⁻². The RGO sheets served as conductor and framework under the PPy layer, which could facilitate electron transfer between RGO and PPy and restrict the swelling and shrinking of PPy, thus resulting in improved electrochemical properties respect to the PPy-fabric device.     

Hierarchical Integrated Hybrid Structural Electrodes Based on Co-N/C and Mo-doped NiCo-LDH@Co-N/C Anchored on MX/CF for High Energy Density Fiber-Shaped Supercapacitor

The judicious design of highly electrochemically active materials on 1D fiber substrate to form a hierarchical integrated hybrid structure is an efficient technique to improve the limited cylindrical space and volumetric energy density of fiber-shaped supercapacitors (FSCs). Herein, a 3D negative electrode, consisting of vertically aligned interconnected mesoporous Co-N/C leaf-like structure on 1D MXene-carbon fiber (Co-N/C@MX/CF) is prepared by controlling the composition and morphology. At the same time, a 3D positive electrode is also prepared by introducing Mo in NiCo-LDH anchored on Co-N/C@MX/CF (Mo-NiCo-LDH@Co-N/C@MX/CF) by electrodeposition method. Benefitting from the systematic hierarchical structures with highly accessible surface area, adequate pore size and easy permeation of electrolyte, both positive and negative electrodes demonstrate highly improved electrochemical performance with areal capacity/capacitance of 0.96 mAh cm⁻²/4.55 mF cm⁻² at a current density of 3.86 mA cm⁻², respectively. Furthermore, the fiber-shaped solid-state hybrid supercapacitor (FSHSC) based on Mo_1.5NiCo-LDH@Co-N/C@MX/CF(+)//Co-N/C_0.5@MX/CF(−) is fabricated, exhibiting compelling energy density of 86.72 mWh cm⁻³ at a power density of 480.30 mW cm⁻³ with an outstanding capacitance retention of 80.2% after 20000 galvanostatic-charge-discharge cycles. This study puts forward a new perspective on the development of highly efficient FSCs for practical application.