A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

Effect of Temperature

Review on the electromagnetic interference shielding properties of carbon based materials and their novel composites: Recent progress, challenges and prospects

The investigation of inexpensive, effective, environmentally friendly next-generation energy storage devices is an urgent task due to the discontinuities of new generation energy that hinder their further widely application. Among the multitudinous explored energy storage devices, supercapacitors have been regarded as the most potential energy storage systems thanks to their distinctive features of ultralong cycling lifespan, ultrafast charge/discharge process, and high power density compared with batteries and conventional capacitors. Nevertheless, the existing defect of low energy density has always been a bottleneck problem to their long-term development and widespread applications. Meanwhile, the electrodes are the core component in supercapacitors, determining the electrochemical performance directly. Consequently, transition metal oxides were chosen as the promoting materials to design and fabricate appropriately and rationally act as supercapacitor electrodes to harvest the outstanding electrochemical performance of both high energy and power density simultaneously. Here, we summarized the recent advances in transition metal oxides with different dimensions as electrodes for high-performance supercapacitors, including zero-dimensional nanostructures (nanospheres, nanocrystals, nanoparticles), one-dimensional nanostructures (nanorods, nanowires and nanotubes), two-dimensional nanostructures (nanoflakes, nanoplatelets), three-dimensional nanostructures (spherical structure, hollow structure, flower-like structure, honeycomb structure, mesoporous structure), and the corresponding supercapacitors electrochemical performance, expecting to make a thorough inquiry of the relationship between structure and property for highlighting the route to design and synthesis high-performance transition metal oxide-based supercapacitor electrodes.

Recent advances in transition metal oxides with different dimensions as electrodes for high-performance supercapacitors

A review on carbon/magnetic metal composites for microwave absorption

As a typical lightweight material, carbon materials have great application prospects in fabricating microwave absorbers. In this work, the Fe3C@Fe/C composites with porous microstructure are obtained by a simple and environmentally friendly method with wasted cornstalks as raw materials. The reflection loss of absorbing composites reaches the minimum value which is less than −50 dB when the thickness is 1.13 mm, while widest effective absorbing bandwidth reaches 5.1 GHz when thickness is 1.50 mm. The stalk-made nanocomposites’ excellent absorbing ability is mainly credit to excellent impedance matching and attenuation characteristics of composites, which is further credit to a synergistic influence of the dielectric loss from the multiple interfaces in porous microstructure and magnetic loss from iron nanoparticles. A low-cost method to obtain microwave absorption materials and realize high-value utilization of agricultural waste to reduce pollution caused by burning cornstalks is put forward.

Lightweight Fe3C@Fe/C nanocomposites derived from wasted cornstalks with high-efficiency microwave absorption and ultrathin thickness

Phase and morphology evolution of high dielectric CoO/Co3O4 particles with Co3O4 nanoneedles on surface for excellent microwave absorption application

As an emerging energy storage device, supercapacitor with high energy density, fast charging/discharging and good cycle stability has aroused great interest. The performance of supercapacitors mainly depends on the electrode material. Manganese dioxide (MnO2) have emerged as one of the most promising electrode materials for high theoretical specific capacitance, wide potential range, high electrochemical activity and environmental friendliness. However, its deteriorated volume expansion and inherently low conductivity limit its development and application in supercapacitors. To circumvent the mentioned issues, the porous, thin film or layered composite materials were prepared to enhance the electrical conductivity and specific surface area of MnO2. Carbon materials are the ideal choice to compound with MnO2 due to their low electrical resistance, significant thermal stability, large specific surface area and porosity. Up to now, several kinds of MnO2/carbon composites as supercapacitor electrodes have been designed and fabricated. Herein, we give a concise review of the latest researches on MnO2/carbon supercapacitor electrodes, focusing on the fabrication strategies and analysing the influencing factors of electrochemical performance of MnO2/carbon materials. An outlook on the possible development directions in future of designing high performance MnO2/carbon materials for the current challenges is also provided.

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Yuping Zhang

Papers

Recent advances in transition metal oxides with different dimensions as electrodes for high-performance supercapacitors

Phase and morphology evolution of high dielectric CoO/Co3O4 particles with Co3O4 nanoneedles on surface for excellent microwave absorption application

MnO2/Carbon Composites for Supercapacitor: Synthesis and Electrochemical Performance

Recent advances in hydrogen generation process via hydrolysis of Mg-based materials: A short review

One-step synthesis of the reduced graphene oxide@NiO composites for supercapacitor electrodes by electrode-assisted plasma electrolysis