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

Beyond conventional hybrid ion capacitors (HICs) based on porous carbon capacitive materials, the introduction of faradaic pseudocapacitance in HICs is an effective method to enhance energy density. Herein, we prepare methylene blue functionalized graphene (MB-X) composites taking advantage of electrostatic and extensive π-conjugated interaction. The test results confirm that the composites have high rate capability and excellent cycle stability on account of the synergistic effect between graphene and MB molecules. In order to improve the safety of HICs, an aqueous electrolyte is a promising candidate as long as the cell voltage can be efficiently increased. Therefore, we skillfully employ aqueous solutions with different pH values as asymmetric electrolytes to assemble HICs, where polyimide acts as the battery material and MB-X serves as the capacitive material. Thanks to the asymmetric electrolytes, the constructed aqueous HICs can operate at a cell voltage of 1.9 V, much larger than the decomposition voltage of water. Moreover, the flexible structure, and reversible and fast redox reactions of both the anode and cathode make the aqueous HICs display a maximum energy density of 48.6 W h kg−1 and a maximum power density of 19 kW kg−1, as well as a long-cycle lifetime with a decay of 0.00172% per cycle.

Metal-free energy storage systems: combining batteries with capacitors based on a methylene blue functionalized graphene cathode

A simple one-step hydrothermal synthesis of cobaltnickel selenide/graphene nanohybrid as an advanced platinum free counter electrode for dye sensitized solar cell

Silver nanowires (AgNWs), as one-dimensional nanometallic materials, have attracted wide attention due to the excellent electrical conductivity, transparency and flexibility, especially in flexible and stretchable electronics. However, the microscopic discontinuities require AgNWs be attached to some carrier for practical applications. Relative to the preparation method, how to integrate AgNWs into the flexible matrix is particularly important. In recent years, plenty of papers have been published on the preparation of conductors based on AgNWs, including printing techniques, coating techniques, vacuum filtration techniques, template-assisted assembly techniques, electrospinning techniques and gelating techniques. The aim of this review is to discuss different assembly method of AgNW-based conducting film and their advantages. Conducting films based on silver nanowires (AgNWs) have been reviewed with a focus on their assembly and their advantages.

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Recent progress for silver nanowires conducting film for flexible electronics

In this work, the percentage of polyethylene (PE) and polypropylene (PP) blend is controlled at 50:50 to make the composite by forming a co-continuous structure with hexagonal boron nitride (h-BN). The h-BN is wrapped by thermoplastic elastomer styrene-ethylene-propylene-styrene (SEPS). This approach enables the localized distribution of h-BN at the interface of the co-continuous structure of PE/PP blend and SEPS phases, allowing the construction of a heat conduction path in the SEPS phase, thereby improving the thermal conductivity of PE/PP. Theoretical calculation predicted the localized distribution of SEPS at the interface of the PE/PP blend to form a co-continuous composite structure. The thermal conductivity of the composites can be improved by 57.7% by adding 10 wt% h-BN, presenting a commercial potential of such composites in certain heat dissipation applications. 

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Improving thermal conductivity of polyethylene/polypropylene by styrene-ethylene-propylene-styrene wrapping hexagonal boron nitride at the phase interface

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Pulsed Laser Deposition of NiSe2 Film on Carbon Nanotubes for High-Performance Supercapacitor

http://www.espublisher.com/uploads/article_pdf/esmm5f112.pdf

Ultrathin MoSe2 Nanosheets Coated on Hollow Carbon Spheres as Efficient Hybrid Catalyst for Hydrogen Evolution Reaction

Metallic nanoparticles (NPs), as an efficient substrate for surface-enhanced Raman scattering (SERS), attract much interests because of their various shapes and sizes. The appropriate size and morphology of metallic NPs are critical to serve as the substrate for achieving an efficient SERS. Pulsed laser deposition (PLD) is one of the feasible physical methods employed to synthesize metallic NPs with controllable sizes and surface characteristics. It has been recognized to be a successful tool for the deposition of SERS substrates due to its good controllability and high reproducibility in the manufacture of metallic NPs. This review provides an overview about the recent advances for the preparation of SERS substrates by PLD technique. The influences of parameters on the sizes and morphologies of metallic NPs during the deposition processes in PLD technique including laser output parameters, gas medium, liquid medium, substrate temperature, and properties of 3D substrate are presented. The applications of SERS substrates produced by PLD in the environmental monitoring and biomedical analysis are summarized. This knowledge could serve as a guideline for the researchers in exploring further applications of PLD technique in the production of SERS substrate.

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Qunlong Wang

Papers

Pulsed Laser Deposition of NiSe2 Film on Carbon Nanotubes for High-Performance Supercapacitor

Ultrathin MoSe2 Nanosheets Coated on Hollow Carbon Spheres as Efficient Hybrid Catalyst for Hydrogen Evolution Reaction

An overview of surface-enhanced Raman scattering substrates by pulsed laser deposition technique: fundamentals and applications