Huaiguo Xue

High performance electrochemical capacitor materials focusing on nickel based materials

Of the two major capacitances contributing to electrochemical storage devices, pseudo-capacitance, which results from the reversible faradaic reactions, can be much higher than the electric double layer capacitance. Transition metal compounds are emerging electrode materials for pseudo-capacitors due to their multiple oxidation states and different ions. As one of the most well-known electroactive inorganic materials, nickel based materials are being developed for this purpose. Nickel based materials have been intensively investigated and evaluated as potential electrode materials for pseudo-capacitors due to their thermal stability and chemical stability, high theoretical specific capacity, low price and environment friendliness. A variety of synthetic methods such as hydrothermal/solvothermal methods, sol–gel, electrodeposition, and the spray deposition method have been successfully applied to prepare nickel based compounds and composite materials. In this review, comprehensive summaries and evaluations have been given to show the recent progress. And we introduce the nickel based compounds and composites electrode materials for supercapacitors via synthesis methods, the electrochemical performances of the electrode materials and the devices.

Facile synthesis of an accordion-like Ni-MOF superstructure for high-performance flexible supercapacitors

Metal–organic frameworks have received increasing attention as promising electrode materials in supercapacitors. In this study, we have successfully synthesized a novel accordion-like Ni-MOF superstructure ([Ni3(OH)2(C8H4O4)2(H2O)4]·2H2O), for the first time, and used it as an electrode material for supercapacitors. The supercapacitors with the novel electrode exhibited excellent electrochemical performance. For example, the accordion-like Ni-MOF electrode showed specific capacitances of 988 and 823 F g−1 at current densities of 1.4 and 7.0 A g−1, respectively, while maintaining outstanding cycling stability (capacitance retention of 96.5% after 5000 cycles at a current density of 1.4 A g−1). More importantly, the accordion-like Ni-MOF and activated carbons were assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 230 mF cm−2 at a current density of 1.0 mA cm−2. The cycle test showed that the device can offer 92.8% capacity of the initial capacitance at 5.0 mA cm−2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 4.18 mW h cm−3 and the maximum power density can also achieve 231.2 mW cm−3.

MoS2-Based Nanocomposites for Electrochemical Energy Storage

Typical layered transition‐metal chalcogenide materials, in particular layered molybdenum disulfide (MoS2) nanocomposites, have attracted increasing attention in recent years due to their excellent chemical and physical properties in various research fieldsHere, a general overview of synthetic MoS2 based nanocomposites via different preparation approaches and their applications in energy storage devices (Li‐ion battery, Na‐ion battery, and supercapacitor) is presented. The relationship between morphologies and the electrochemical performances of MoS2‐based nanocomposites in the three typical and promising rechargeable systems is also discussed. Finally, perspectives on major challenges and opportunities faced by MoS2‐based materials to address the practical problems of MoS2‐based materials are presented.

Effect of inhibitors on Zn-dendrite formation for zinc-polyaniline secondary battery

Abstract The effects of Pb2+, sodium lauryl sulfate and Triton X-100 on inhibition of Zn-dendrite growth in Zn-polyaniline batteries were studied by scanning electron micrograph and cyclic voltammetry. The results show that Triton X-100 in the region of 0.02–500 ppm in the electrolyte containing 2.5 M ZnCl2 and 2.0 M NH4Cl with pH 4.40 can effectively inhibit zinc-dendrite growth during charge–discharge cycles of the battery and yield longer cycles.

Transition metal oxides with one-dimensional/one-dimensional-analogue nanostructures for advanced supercapacitors

With the increasing energy demand and the overconsumption of fossil fuels, renewable energy-storage devices with higher efficiency are of great interest. In particular, supercapacitors have recently gained significant attention due to their excellent charge–discharge performance, long-term cycle lifetimes, and high specific power. In addition, supercapacitors could also make up the difference in energy and power between batteries and traditional capacitors. In the future, the promising family of transition metal oxides (TMOs) will play a significant role in environmentally friendly, low-cost, and high-powered energy storage. Furthermore, one-dimensional (1D) and one-dimensional-analogue nanostructures could remarkably enhance the characteristic properties of TMOs. In this review, we focused on the recent progress in the preparation and electrochemical properties of the next-generation supercapacitors.

Bioelectrochemical characteristics of glucose oxidase immobilized in a polyaniline film

Abstract Glucose biosensors have been prepared by both adsorption and electrochemical doping on/in a polyaniline film. The experimental results of the cyclic voltammograms and impedance measurements show that the characteristics of the glucose biosensor formed by electrochemical doping are different from those of the biosensor formed by adsorption. X-ray photoelectron spectroscopy (XPS) experiments reveal that the chemical shifts of N 1s and O 1s in polyaniline doped electrochemically with glucose oxidase are greater than those for adsorption, i.e., the binding force between glucose oxidase and polyaniline for electrochemical doping is stronger than that for adsorption. Glucose oxidase adsorbed on a polyaniline film desorbs more easily than that doped electrochemically in the film. The glucose biosensor formed by electrochemical doping has a high operational stability and long storage stability of 36 months. Up to now this biosensor is still working. The biosensor has been used for the determination of glucose in human blood.

Rechargeable zinc–air batteries: a promising way to green energy

As a promising technology, electrically rechargeable zinc–air batteries have gained significant attention in the past few years. Herein, in this review, we focused on the main challenges of the electrically rechargeable zinc–air batteries in alkaline electrolytes and the up-to-date progress from materials to technologies towards overcoming these technical barriers. We first overviewed the design and working mechanism of the battery and classified the hindrances into dendritic growth at the anode, lack of higher performance bifunctional catalysts at the air electrode, and electrolyte-related problems. Then, detailed discussions have been provided on the latest progress to address these technical issues based on the nano/micro-materials. Flexible zinc–air batteries as a new development have also been discussed in a separate section. Finally, conclusions have been provided followed by future perspective.

Nanoparticle/MOF composites: preparations and applications

Over the last twenty years, MOFs have emerged as a new promising porous material in the areas of gas sorption and separation, catalysis, drug delivery, and molecule sensing. Moreover, nanomaterials have also attracted widespread attention in recent years. Owing to the porous structure of MOFs, we can combine nanoparticles with MOFs to obtain nanoparticle/MOF composites, which possess the advantages of both parent materials. In the present study, we utilized two main methods to introduce nanoparticles into MOFs: a method employing MOFs as templates to hold guest nanoparticles in their channels and a method employing the encapsulation of pre-synthesized nanoparticles. The former includes chemical vapor deposition, solid grinding, liquid impregnation, and double solvent methods, and the latter comprises some new techniques such as the self-sacrificing template technique. Herein, we also reviewed their applications in hydrogen storage, ammonia adsorption, acidic gas adsorption, catalytic processes, and energy storage.

Facile synthesis of amorphous aluminum vanadate hierarchical microspheres for supercapacitors

Micro-nanostructured mixed metal vanadates have recently garnered enormous attention owing to their remarkable performances in catalysis, energy storage and conversion. In this work, we report the synthesis of amorphous aluminum vanadate hierarchical microspheres via a simple hydrothermal approach with polyvinylpyrrolidone as a surface directing agent. Amorphous aluminum vanadate hierarchical microspheres are firstly described as a kind of electrode material for supercapacitors. The measured specific capacitance of the amorphous aluminum vanadate electrode is 497 F g−1 at 1 A g−1 with good stability and a retention capacity of 89% after 10 000 cycles. In addition, the fabricated asymmetric supercapacitor device delivered better performance with an extended operating voltage window of 1.5 V, excellent cycle stability (10 000 cycles, 85% capacitance retention), high energy density (37.2 W h kg−1 at 1124.4 W kg−1) and high power density (11 250 W kg−1 at 25 W h kg−1). This study essentially offers a new kind of vanadate as an electrochemical active material for the development of supercapacitors.

Facile synthesis of ultrathin Ni-MOF nanobelts for high-efficiency determination of glucose in human serum

Ultrathin Ni-MOF nanobelts, [Ni20(C5H6O4)20(H2O)8]·40H2O(Ni-MIL-77 NBs), were synthesized by a facile one-pot solution process and can be used as an efficient catalyst electrode for glucose oxidation under alkaline conditions. Electrochemical measurements demonstrate that the NB/GCE, when used as a non-enzymatic glucose sensor, offers superior analytical performances with a wide linear range (from 1 μM to 500 μM), a low detection limit (0.25 μM, signal-to-noise = 3), and a response sensitivity of 1.542 μA mM-1 cm-2. Moreover, it can also be applied for glucose detection in human blood serum with the relative standard deviation (RSD) of 7.41%, showing the high precision of the sensor in measuring real samples.