Qiulong Li

Large-area fabrication of periodic Fe nanorings with controllable aspect ratios in porous alumina templates.

Highly uniform Fe nanoring arrays in porous anodic alumina templates are fabricated by physical vapour deposition and grazing ion milling techniques. The nanorings have aspect ratios ranging from 0.8 to 4, depending on the deposition conditions. The outer diameter of the individual nanorings, and the area density and distribution patterns are completely determined by the template used. Selected-area electron diffraction reveals that these nanorings have a polycrystalline microstructure. The nanoring fabrication method demonstrated here can be extended to other materials.

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.

Double glass transitions in exfoliated poly(methyl methacrylate)/organically modified MgAl layered double hydroxide nanocomposites

A series of nanocomposites based on poly(methyl methacrylate) (PMMA) and organically modified MgAl layered double hydroxides (O-LDH) were synthesized via in situ polymerization. The modification of LDH by sodium dodecylbenzenesulfonate (SDBS) resulted in an enlarged interlayer distance and a nearly complete substitution of the original NO3− in LDH layers. The polymerization of methyl methacrylate led to a disorderly exfoliated LDH in the PMMA matrix. The results of dynamic mechanical analysis (DMA) showed that there were two tan δ peaks in the PMMA/O-LDH nanocomposites at low frequencies. And the second peak at about 80 °C higher than the main peak (glass transition of PMMA matrix) gradually disappeared with increasing frequency, corresponding to the glass transition of PMMA chains confined on the O-LDH surface. Both of the two peaks shifted to higher temperature with increasing heating rate due to the strain lag of the sample.

Solvothermal synthesis of gallium-doped zinc oxide nanoparticles with tunable infrared absorption

The doping of ZnO nanoparticles (NPs) has been attracting a lot of attention both for fundamental studies and potential applications. In this manuscript, we report the preparation of gallium doped zinc oxide (GZO) NPs through the solvothermal method. In order to obtain the effective Ga doping in the ZnO crystalline lattice, we identified the optimal reaction conditions in terms of different Zn precursors, temperature, and heating rate. The results show that GZO NPs with tunable infrared absorption can be received using different molar ratios of Ga(NO3)3 and zinc stearate (Zn[CH3(CH2)16COO]2, ZnSt2) kept in the sealed autoclaves at 160 °C for 8 h. Furthermore, the growth of the GZO NPs was investigated by monitoring the optical absorption spectral and the corresponding chemical composition of aliquots extracted at different reaction time intervals.

In Situ Generation of Photosensitive Silver Halide for Improving the Conductivity of Electrically Conductive Adhesives

Electrically conductive adhesives (ECAs) can be regarded as one of the most promising materials to replace tin/lead solder. However, relatively low conductivity seriously restricts their applications. In the present study, we develop an effective method to decrease the bulk electrical resistivity of ECAs. KI or KBr is added to replace the lubricant and silver oxide layers on silver flakes and to form photosensitive silver halide. After exposure to sunlight, silver halide can photodecompose into silver nanoparticles that will sinter and form metallic bonding between/among flakes during the curing process of ECAs, which would remarkably reduce the resistivity. The modified micro silver flakes play a crucial role in decreasing the electrical resistivity of the corresponding ECAs, exhibiting the lowest resistivity of 7.6 × 10-5 Ω·cm for 70 wt % loaded ECAs. The obtained ECAs can have wide applications in the electronics industry, where high conductance is required.

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.