Juan Sun

Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density

The emergence of fiber-shaped supercapacitors (FSSs) has led to a revolution in portable and wearable electronic devices. However, obtaining high energy density FSSs for practical applications is still a key challenge. This article exhibits a facile and effective approach to directly grow well-aligned three-dimensional vanadium nitride (VN) nanowire arrays (NWAs) on carbon nanotube (CNT) fiber with an ultrahigh specific capacitance of 715 mF/cm2 in a three-electrode system. Benefiting from their intriguing structural features, we successfully fabricated a prototype asymmetric coaxial FSS (ACFSS) with a maximum operating voltage of 1.8 V. From core to shell, this ACFSS consists of a CNT fiber core coated with VN@C NWAs as the negative electrode, Na2SO4 poly(vinyl alcohol) (PVA) as the solid electrolyte, and MnO2/conducting polymer/CNT sheets as the positive electrode. The novel coaxial architecture not only fully enables utilization of the effective surface area and decreases the contact resistance between the two electrodes but also, more importantly, provides a short pathway for the ultrafast transport of axial electrons and ions. The electrochemical results show that the optimized ACFSS exhibits a remarkable specific capacitance of 213.5 mF/cm2 and an exceptional energy density of 96.07 μWh/cm2, the highest areal capacitance and areal energy density yet reported in FSSs. Furthermore, the device possesses excellent flexibility in that its capacitance retention reaches 96.8% after bending 5000 times, which further allows it to be woven into flexible electronic clothes with conventional weaving techniques. Therefore, the asymmetric coaxial architectural design allows new opportunities to fabricate high-performance flexible FSSs for future portable and wearable electronic devices.

Constructing Ultrahigh-Capacity Zinc–Nickel–Cobalt Oxide@Ni(OH)2 Core–Shell Nanowire Arrays for High-Performance Coaxial Fiber-Shaped Asymmetric Supercapacitors

Increased efforts have recently been devoted to developing high-energy-density flexible supercapacitors for their practical applications in portable and wearable electronics. Although high operating voltages have been achieved in fiber-shaped asymmetric supercapacitors (FASCs), low specific capacitance still restricts the further enhancement of their energy density. This article specifies a facile and cost-effective method to directly grow three-dimensionally well-aligned zinc-nickel-cobalt oxide (ZNCO)@Ni(OH)2 nanowire arrays (NWAs) on a carbon nanotube fiber (CNTF) with an ultrahigh specific capacitance of 2847.5 F/cm3 (10.678 F/cm2) at a current density of 1 mA/cm2, These levels are approximately five times higher than those of ZNCO NWAs/CNTF electrodes (2.10 F/cm2) and four times higher than Ni(OH)2/CNTF electrodes (2.55 F/cm2). Benefiting from their unique features, we successfully fabricated a prototype coaxial FASC (CFASC) with a maximum operating voltage of 1.6 V, which was assembled by adopting ZNCO@Ni(OH)2 NWAs/CNTF as the core electrode and a thin layer of carbon coated vanadium nitride (VN@C) NWAs on a carbon nanotube strip (CNTS) as the outer electrode with KOH poly(vinyl alcohol) (PVA) as the gel electrolyte. A high specific capacitance of 94.67 F/cm3 (573.75 mF/cm2) and an exceptional energy density of 33.66 mWh/cm3 (204.02 μWh/cm2) were achieved for our CFASC device, which represent the highest levels of fiber-shaped supercapacitors to date. More importantly, the fiber-shaped ZnO-based photodetector is powered by the integrated CFASC, and it demonstrates excellent sensitivity in detecting UV light. Thus, this work paves the way to the construction of ultrahigh-capacity electrode materials for next-generation wearable energy-storage devices.

Constructing hierarchical dandelion-like molybdenum–nickel–cobalt ternary oxide nanowire arrays on carbon nanotube fiber for high-performance wearable fiber-shaped asymmetric supercapacitors

Emerging fiber-shaped supercapacitors have been considered as promising new-state energy storage devices for next-generation wearable electronics. However, the limited energy densities arising from the small specific capacitance and low operating voltage severely restrict their practical application. Here, we develop a facile and effective method to directly grow dandelion-like molybdenum–nickel–cobalt ternary oxide (MNCO) nanowire arrays (NWAs) on carbon nanotube fiber (CNTF) with a high specific capacitance of 490.7 F cm−3 (1840 mF cm−2) at a current density of 1 mA cm−2. Benefiting from the three-dimensional nanostructure, high conductivity and excellent pseudocapacitance properties, we successfully fabricate a fiber-shaped asymmetric supercapacitor (FASC) with a maximum operating voltage of 1.6 V, which is assembled by twisting a MNCO/CNTF positive electrode and thin carbon-coated VN NWAs on CNTF negative electrode together with KOH/poly(vinyl alcohol) (PVA) as the gel electrolyte. The optimized FASC delivers a remarkable specific capacitance of 62.3 F cm−3 (233.7 mF cm−2) and an exceeding energy density of 22.2 mW h cm−3 (83.1 μW h cm−2). Additionally, it exhibits outstanding flexibility with capacitance retention maintained at 90.2% after bending 3500 times. Thus, the high performance MNCO/CNTF electrode opens a new avenue to fabricate high-performance FASCs for next-generation wearable energy storage devices.

Hierarchical ferric-cobalt-nickel ternary oxide nanowire arrays supported on graphene fibers as high-performance electrodes for flexible asymmetric supercapacitors

Fiber-based supercapacitors (FSCs) are new members of the energy storage family. They present excellent flexibility and have promising applications in lightweight, flexible, and wearable devices. One of the existing challenges of FSCs is enhancing their energy density while retaining the flexibility. We developed a facile and cost-effective method to fabricate a highly capacitive positive electrode based on hierarchical ferric-cobalt-nickel ternary oxide nanowire arrays/graphene fibers and a negative electrode based on polyaniline-derived carbon nanorods/graphene fibers. The elegant microstructures and excellent electrochemical performances of both electrodes enabled us to construct a highperformance flexible asymmetric graphene fiber-based supercapacitor device with an operating voltage of 1.4 V, a specific capacitance up to 61.58 mF·cm–2, and an energy density reaching 16.76 μW·h·cm–2. Moreover, the optimal device presents an outstanding cycling stability with 87.5% initial capacitance retention after 8,000 cycles, and an excellent flexibility with a capacitance retention of 90.9% after 4,000 cycles of repetitive bending.

Facile synthesis of hierarchical porous manganese nickel cobalt sulfide nanotube arrays with enhanced electrochemical performance for ultrahigh energy density fiber-shaped asymmetric supercapacitors

To create high energy density fiber-shaped supercapacitors (FSCs), a new class of hierarchical electrodes with high electrical conductivity and good mechanical stability is needed. Here, a novel electrode consisting of porous manganese–nickel–cobalt sulfide (MNCS) multi-tripod nanotube arrays (NTAs) on carbon nanotube fibers (CNTFs) is prepared by a facile and cost-effective synthesis. The MNCS NTAs/CNTF electrode achieves a high specific capacitance of 2554.5 F cm−3, which is attributed to the high electrical conductivity and richer redox reactions of MNCS NTAs resulting from mixing three metal elements followed by sulfidation, and high porosity but a robust architecture. The unique features of these electrodes allowed us to successfully fabricate a fiber-shaped asymmetric supercapacitor (FASC) with a maximum operating voltage of 1.6 V by using the vanadium nitride (VN) nanowires (NWs) on CNTF electrode as the negative electrode. A volumetric capacitance of 147.3 F cm−3 and an energy density of 52.4 mW h cm−3 of the as-obtained FASC device are higher than those reported for similar devices. In addition, our FASC device possesses outstanding reliability and achieves a retaining capacitance of 92.9% after 5000 bending cycles. Thus, this work develops hierarchical, porous MNCS multi-tripod NTAs as a promising candidate for next-generation electrode materials with high electrochemical performance.

High-performance flexible all-solid-state aqueous rechargeable Zn–MnO2 microbatteries integrated with wearable pressure sensors

The ever-increasing demand for smart personal electronics has promoted the rapid development of wearable multiple functionalities integrated configurations. However, it is still a great challenge to realize both high-performance energy storage devices and functional sensors in a single device to obtain a stable, self-powering, multifunctional, miniaturized integrated system. Herein, we report an ultrathin microbattery-pressure sensor integrated system to simultaneously achieve energy storage and pressure detection in a single device. Energy storage is achieved by an in-plane, interdigitated, flexible, all-solid-state, aqueous rechargeable Ni@MnO2//Zn microbattery in a thin polydimethylsiloxane film, using MnO2 nanosheets directly deposited on highly conductive 3D Ni skeletons (Ni@MnO2) as an advanced binder-free cathode. Benefiting from synergy between the high electrochemical performance of MnO2 and the outstanding conductivity of 3D highly conductive Ni skeletons, the assembled Ni@MnO2//Zn microbattery displays a high capacity of 0.718 mA h cm−2 and a correspondingly impressive energy density of 0.98 mW h cm−2. More importantly, the wearable pressure sensor, which is powered by the integrated Ni@MnO2//Zn microbattery, can achieve real-time health monitoring both statically and dynamically. Thus, this work paves the way to develop high-performance, multifunctional, miniaturized integrated configurations for portable and wearable electronics.

All-Metal-Organic Framework-Derived Battery Materials on Carbon Nanotube Fibers for Wearable Energy-Storage Device

The ever-increasing demands for portable and wearable electronics continue to drive the development of high-performance fiber-shaped energy-storage devices. Metal-organic frameworks (MOFs) with well-tunable structures and large surface areas hold great potential as precursors and templates to form porous battery materials. However, to date, there are no available reports about fabrication of wearable energy-storage devices on the utilization of all-MOF-derived battery materials directly grown on current collectors. Here, MOF-derived NiZnCoP nanosheet arrays and spindle-like α-Fe2O3 on carbon nanotube fibers are successfully fabricated with impressive electrochemical performance. Furthermore, the resulting all-solid-state fiber-shape aqueous rechargeable batteries take advantage of large specific surface area and abundant reaction sites of well-designed MOF-derived electrode materials to yield a remarkable capacity of 0.092 mAh cm-2 and admirable energy density of 30.61 mWh cm-3, as well as superior mechanical flexibility. Thus, this research may open up exciting opportunities for the development of new-generation wearable aqueous rechargeable batteries.

3D Printing Fiber Electrodes for an All‐Fiber Integrated Electronic Device via Hybridization of an Asymmetric Supercapacitor and a Temperature Sensor

Abstract Wearable fiber‐shaped electronic devices have drawn abundant attention in scientific research fields, and tremendous efforts are dedicated to the development of various fiber‐shaped devices that possess sufficient flexibility. However, most studies suffer from persistent limitations in fabrication cost, efficiency, the preparation procedure, and scalability that impede their practical application in flexible and wearable fields. In this study, a simple, low‐cost 3D printing method capable of high manufacturing efficiency, scalability, and complexity capability to fabricate a fiber‐shaped integrated device that combines printed fiber‐shaped temperature sensors (FTSs) with printed fiber‐shaped asymmetric supercapacitors (FASCs) is developed. The FASCs device can provide stable output power to FTSs. Moreover, the temperature responsivity of the integrated device is 1.95% °C−1.

Metal–Organic Framework Derived Spindle-like Carbon Incorporated α-Fe2O3 Grown on Carbon Nanotube Fiber as Anodes for High-Performance Wearable Asymmetric Supercapacitors

Iron oxide (Fe2O3) has drawn much attention because of its high theoretical capacitance, wide operating potential window, low cost, natural abundance, and environmental friendliness. However, the inferior conductivity and insufficient ionic diffusion rate of a simple Fe2O3 electrode leading to the low specific capacitance and poor rate performance of supercapacitors have impeded its applications. In this work, we report a facile and cost-effective method to directly grow MIL-88-Fe metal-organic framework (MOF) derived spindle-like α-Fe2O3@C on oxidized carbon nanotube fiber (S-α-Fe2O3@C/OCNTF). The S-α-Fe2O3@C/OCNTF electrode is demonstrated with a high areal capacitance of 1232.4 mF/cm2 at a current density of 2 mA/cm2 and considerable rate capability with capacitance retention of 63% at a current density of 20 mA/cm2 and is well matched with the cathode of the Na-doped MnO2 nanosheets on CNTF (Na-MnO2 NSs/CNTF). The electrochemical test results show that the S-α-Fe2O3@C/OCNTF//Na-MnO2 NSs/CNTF asymmetric supercapacitors possess a high specific capacitance of 201.3 mF/cm2 and an exceptional energy density of 135.3 μWh/cm2. Thus, MIL-88-Fe MOF derived S-α-Fe2O3@C will be a promising anode for applications in next-generation wearable asymmetric supercapacitors.

Facile Synthesis of Na-Doped MnO2 Nanosheets on Carbon Nanotube Fibers for Ultrahigh-Energy-Density All-Solid-State Wearable Asymmetric Supercapacitors

Flexible fiber-shaped supercapacitors hold promising potential in the area of portable and wearable electronics. Unfortunately, their general application is hindered by the restricted energy densities due to low operating voltage and small specific surface area. Herein, an all-solid-state fiber-shaped asymmetric supercapacitor (FASC) possessing ultrahigh energy density is reported, in which the positive electrode was designed as Na-doped MnO2 nanosheets on carbon nanotube fibers (CNTFs) and the negative electrode as MoS2 nanosheet-coated CNTFs. Owing to the excellent properties of the designed electrodes, our FASCs exhibit a large operating potential window (0-2.2 V), a remarkable specific capacitance (265.4 mF/cm2), as well as an ultrahigh energy density (178.4 μWh/cm2). Moreover, the devices are of outstanding mechanical flexibility.