Toward Enhancing Wearability and Fashion of Wearable Supercapacitor with Modified Polyurethane Artificial Leather Electrolyte

Trimetallic Oxides/GO Composites Optimized with Carbon Ions Radiations for Supercapacitive Electrodes

Hydrothermally synthesized electrodes of Co3O4@MnO2@NiO/GO were produced for use in supercapacitors. Graphene oxide (GO) was incorporated into the nanocomposites used for electrode synthesis due to its great surface area and electrical conductivity. The synergistic alliance among these composites and GO enhances electrode performance, life span, and stability. The structural properties obtained from the X-ray diffraction (XRD) results suggest that nanocomposites are crystalline in nature. The synergistic alliance among these composites and GO enhances electrode performance, life span, and stability. Performance assessment of these electrodes indicates that their characteristic performance was enhanced by C2+ radiation, with the uttermost performance witnessed for electrodes radiated with 5.0 × 1015 ions/cm2.

High-Performance-Integrated Stretchable Supercapacitors Based on a Polyurethane Organo/Hydrogel Electrolyte

Stretchable supercapacitors (SSCs) are promising energy storage devices for emerging wearable electronics. However, the low-energy density and poor deformation performance are still a challenge. Herein, an amphiphilic polyurethane-based organo/hydrogel electrolyte (APUGE) with a H₂O/AN-in-salt (H₂O/AN-NaClO₄) is prepared for the first time. The as-prepared APUGE shows a wide voltage window (∼2.3 V), good adhesion, and excellent resilience. In addition, the intrinsically stretchable electrodes are prepared by coating the activated carbon slurry onto the PU/carbon black/MWCNT conductive elastic substrate. Based on the strong interface adhesion of the PU matrix, the as-assembled SSC delivers high-energy density (5.65 mW h cm^-3 when the power density is 0.0256 W cm^-3) and excellent deformation stability with 94.5% capacitance retention after 500 stretching cycles at 100% strain. This fully integrated construction concept is expected to be extended to multisystem stretchable metal ion batteries, stretchable lithium-sulfur batteries, and other stretchable energy storage devices.

A leather-based electrolyte for all-in-one configured flexible supercapacitors

Leather based gel electrolytes were prepared from the top down method, and integrated flexible supercapacitors were developed by this method.

Conductive electrodes of metallic-organic compound CH3CuS nanowires for all-solid-state flexible supercapacitors

Development of wearable electronics puts forward higher requirements for flexible energy storage devices. Lighter and thinner electrodes with high conductivity are one of the key factors to meet this demand. Herein, a conductive paper-based electrode, assembled from metallic-organic compound CH₃CuS nanowires prepared by a one-step thermal solution process, is reported. By using the conductive electrodes of CH₃CuS nanowires, the fabricated all-solid-state supercapacitor device delivers an excellent electrochemical performance: an areal capacitance of 90.5 μF cm^-2 at a current density of 0.5 mA cm^-2, an energy density of 5.2 μW h cm^-2, and 98% retention of initial capacitance after undergoing 10 000 cycles. In particular, the fabricated all-solid-state supercapacitor device can work normally under a bent state. The no-additive, cost-effective, and eco-friendly paper-based electrodes present a potential application prospect in the field of flexible energy storage devices.

Latest Advances in Flexible Symmetric Supercapacitors: From Material Engineering to Wearable Applications

Flexible symmetric supercapacitors (FSSs) have received enormous attention in energy storage and conversion areas by virtue of their superior flexibility, high power density, and good cycling stability. FSS devices are typically composed of one solid electrolyte layer laminated by two electrode layers, which can realize energy storage, response to electrical stimulus, and even detect external stress or strain change based on various working mechanisms. The as-mentioned multifunctions of FSS devices are expected to play many critical roles in practical applications of wearable power supply and in artificial intelligence. This realization strongly associates with the rapid development of materials science and engineering, especially nanomaterials and smart structure design, and the multifunctions are results of rational designs of critical materials, optimization of device dimensions, and selectivity of active ion species.This Account showcases the latest advances in FSS devices concerning several critical aspects from fundamental material engineering to practical wearable applications. We first describe advanced functional materials utilized in flexible solid electrolytes and electrodes of FSS systems. Several highly ion-conductive hydrogel and ionogel electrolytes with excellent mechanical properties have been designed for the fast and stable ionic migration kinetics in devices. Some high-performance electrode materials with high charge storage capacity, efficient electromechanical conversion, and sensitive ionic response are presented for realizing multifunctions of FSS devices. After that, analysis of interfaces in devices on their performances is provided, and the construction strategies of robust interface are displayed as well. We then summarize flexible and wearable applications of FSS devices, including high-energy density power sources, flexible and electroactive actuators, and wearable and sensitive sensors. These multifunctions are realized by optimization of device dimensions, control of ion migration kinetics, and development of advanced materials, and the corresponding working mechanisms of the devices are presented in detail. The long-term development and future research directions of FSS devices are also envisioned.At present, the rise of nanomaterials and nanoscience is providing great opportunity to further improve performances of FSS devices and finally realize their wearable applications. These wearable FSS devices with smart multifunctions will significantly promote the development of next-generation flexible electronics for artificial intelligence. It is expected that this Account can promote tremendous efforts toward fundamental clarification of FSS devices, and the design mentality will accelerate the development of other flexible and wearable electrochemical energy devices.

Free-standing NiCoSe2 nanostructure on Ni foam via electrodeposition as high-performance asymmetric supercapacitor electrode

Designing a high-energy-density and power-density electrode for supercapacitors has become an increasingly important concept in the energy storage community. In this article, NiCoSe₂ nanostructures were electrodeposited on nickel (Ni) foam and directly used as electrodes for supercapacitors. The effect on the morphology and electrochemical performance of NiCoSe₂ prepared under different scan rates was measured through scanning electron microscopy and various electrochemical measurements. The resultant NiCoSe₂ prepared with 5 mV s^-1 exhibits a cross-linked porous nanostructure and a high specific capacitance of 2185 F g^-1 at a current density of 1 A g^-1. Taking advantage of these features, an ASC is constructed by using NiCoSe₂ on Ni foam as the positive electrode and an active carbon electrode as the negative electrode with 3 M KOH as the electrolyte. The ASC displays a high-energy density of 41.8 Wh kg^-1, an ultrahigh power output of 8 kW kg^-1, as well as a long cycling life (91.4% capacity retention after 10 000 cycles). The excellent electrochemical performance makes the porous NiCoSe₂ nanostructures a promising alternative in energy storage devices.

Highly flexible reduced graphene oxide@polypyrrole-polyethylene glycol foam for supercapacitors

A flexible and free-standing 3D reduced graphene oxide@polypyrrole–polyethylene glycol (RGO@PPy–PEG) foam was developed for wearable supercapacitors. The device was fabricated sequentially, beginning with the electrodeposition of PPy in the presence of a PEG–borate on a sacrificial Ni foam template, followed by a subsequent GO wrapping and chemical reduction process. The 3D RGO@PPy–PEG foam electrode showed excellent electrochemical properties with a large specific capacitance of 415 F g⁻¹ and excellent long-term stability (96% capacitance retention after 8000 charge–discharge cycles) in a three electrode configuration. An assembled (two-electrode configuration) symmetric supercapacitor using RGO@PPy–PEG electrodes exhibited a remarkable specific capacitance of 1019 mF cm⁻² at 2 mV s⁻¹ and 95% capacitance retention over 4000 cycles. The device exhibits extraordinary mechanical flexibility and showed negligable capacitance loss during or after 1000 bending cycles, highlighting its great potential in wearable energy devices.

A flexible and free-standing 3D reduced graphene oxide@polypyrrole–polyethylene glycol (RGO@PPy–PEG) foam was developed for wearable supercapacitors.

A Review on Nano-/Microstructured Materials Constructed by Electrochemical Technologies for Supercapacitors

The article reviews the recent progress of electrochemical techniques on synthesizing nano-/microstructures as supercapacitor electrodes. With a history of more than a century, electrochemical techniques have evolved from metal plating since their inception to versatile synthesis tools for electrochemically active materials of diverse morphologies, compositions, and functions. The review begins with tutorials on the operating mechanisms of five commonly used electrochemical techniques, including cyclic voltammetry, potentiostatic deposition, galvanostatic deposition, pulse deposition, and electrophoretic deposition, followed by thorough surveys of the nano-/microstructured materials synthesized electrochemically. Specifically, representative synthesis mechanisms and the state-of-the-art electrochemical performances of exfoliated graphene, conducting polymers, metal oxides, metal sulfides, and their composites are surveyed. The article concludes with summaries of the unique merits, potential challenges, and associated opportunities of electrochemical synthesis techniques for electrode materials in supercapacitors.

Phase Transition Induced Unusual Electrochemical Performance of V2CTX MXene for Aqueous Zinc Hybrid-Ion Battery

Nonbattery behavior related phase transition of electrodes is usually not favorable for any batteries because it results in performance degradation at all times. Here, we demonstrate a zinc hybrid-ion battery (ZHIB) with an unusual capacity enhancement even within 18 000 cycles by employing V₂CT_X MXene as the cathode, enormously differing from all reported counterparts with capacity degradation initiated within hundreds of cycles. The dominated mechanisms are determined to be MXene delamination and an unexpected phase transition during cycling. Both the original cathode and secondary derivative contribute to capacity simultaneously, resulting in the unusual capacity enhancement. Consequently, the specific capacity of 508 mAh g^-1 (highest for all reported aqueous zinc-ion batteries) and high energy density of 386.2 Wh kg^-1 are realized. Also, the quasi-solid-state batteries fabricated can output stably at -20 °C and in bending, twisting, stabbing, and cutting conditions. Our work brings an effective approach, that is, utilizing "unstable" electrode materials, which should usually be avoided, to achieve continuously enhanced performance of a battery. The idea to use both original and secondary materials for energy storage may be developed to be a general method to achieve extraordinary cycling stability of batteries.

TiN Paper for Ultrafast-Charging Supercapacitors

Ultrafast-charging energy storage devices are attractive for powering personal electronics and electric vehicles. Most ultrafast-charging devices are made of carbonaceous materials such as chemically converted graphene and carbon nanotubes. Yet, their relatively low electrical conductivity may restrict their performance at ultrahigh charging rate. Here, we report the fabrication of a porous titanium nitride (TiN) paper as an alternative electrode material for ultrafast-charging devices. The TiN paper shows an excellent conductivity of 3.67 × 10⁴ S m^-1, which is considerably higher than most carbon-based electrodes. The paper-like structure also contains a combination of large pores between interconnected nanobelts and mesopores within the nanobelts. This unique electrode enables fast charging by simultaneously providing efficient ion diffusion and electron transport. The supercapacitors (SCs) made of TiN paper enable charging/discharging at an ultrahigh scan rate of 100 V s^-1 in a wide voltage window of 1.5 V in Na₂SO₄ neutral electrolyte. It has an outstanding response time with a characteristic time constant of 4 ms. Significantly, the TiN paper-based SCs also show zero capacitance loss after 200,000 cycles, which is much better than the stability performance reported for other metal nitride SCs. Furthermore, the device shows great promise in scalability. The filtration method enables good control of the thickness and mass loading of TiN electrodes and devices.

Toward Flexible and Wearable Embroidered Supercapacitors from Cobalt Phosphides-Decorated Conductive Fibers

Wearable supercapacitors (SCs) are gaining prominence as portable energy storage devices. To develop high-performance wearable SCs, the significant relationship among material, structure, and performance inspired us with a delicate design of the highly wearable embroidered supercapacitors made from the conductive fibers composited. By rendering the conductive interdigitally patterned embroidery as both the current collector and skeleton for the SCs, the novel pseudocapacitive material cobalt phosphides were then successfully electrodeposited, forming the first flexible and wearable in-plane embroidery SCs. The electrochemical measurements manifested that the highest specific capacitance was nearly 156.6 mF cm^-2 (65.72 F g^-1) at the current density of 0.6 mA cm^-2 (0.25 A g^-1), with a high energy density of 0.013 mWh cm^-2 (5.55 Wh kg^-1) at a power density of 0.24 mW cm^-2 (100 W kg^-1). As a demonstration, a monogrammed pattern was ingeniously designed and embroidered on the laboratory gown as the wearable in-plane SCs, which showed both decent electrochemical performance and excellent flexibility.