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The vacuum impregnation resin method was used to prepare composite bipolar plates in fuel cell in this study. The effects of the content of epoxy resin diluent added, temperature and pore structure of graphite on the impregnation content during the vacuum impregnation process were studied. The electrical conductivity, flexural strength and airtightness of the prepared fuel cell bipolar plates were investigated. The results show that increasing the content of diluent and temperature can reduce viscosity and increase the upper limit of resin impregnation, enabling the resin to impregnate and fill into smaller pores, while there are still some pores that cannot be filled and saturated, such as the pores below 0.1 μm are difficult to fully penetrate in the expanded graphite plate, resulting in the resin being unable to completely fill the entire pores of the expanded graphite. The optimal temperature for impregnating the epoxy resin/diluent system by vacuum impregnation is 50 ℃, and the optimal addition ratio of diluent ethylene glycol diglycidyl ether is 15%(mass fraction). The obtained bipolar plate has excellent electrical conductivity of 340.12 S/cm, flexural strength of 41.52 MPa, and helium permeability of 5.4×10-7 cm3·cm-2·s-1.

Bipolar plates play a role in electron transfer, gas distribution, water management, supporting membrane electrode assembly in the proton exchange membrane fuel cell (PEMFC) and is also a key component to ensure low cost of fuel cell stack. In this paper, bipolar plate materials (metal, graphite and composite materials), functions, advantages and challenges are reviewed. Among them, the composite graphite bipolar plate stands out with its long cycle life and high corrosion resistance, and has received high attention in recent years. The factors related to the conductive network formed by graphite (including the size and shape of filler and the auxiliary filler bridging graphite particles), the composition and curing conditions of polymer, and the influence of the molding process conditions on the properties were discussed in this paper. In the future, the development of composite graphite bipolar plates with excellent comprehensive performance, making existing formulas and forming methods suitable for large-scale production by mastering and optimizing the balance between polymer structure and reaction path on their performance, will greatly enhance the large-scale application of proton exchange membrane fuel cells in more fields.

Lithium-ion capacitors are energy storage devices between lithium-ion batteries and supercapacitors, which have both high energy density and high power density, and are considered as one of the most promising energy storage systems. In this paper, the research progress of carbon-based and lithium-embedded cathode materials in recent years was summarized, and the classification and modification methods of carbon-based and lithium-embedded electrode materials were introduced in detail. In order to further improve the performance of lithium-ion capacitors, researchers further optimized the cathode materials by means of microstructure regulation, surface modification, doping modification and composite materials, and carried out cathode and anode dynamic matching to comprehensively improve the electrochemical performance of lithium-ion capacitors. Finally, the research hotspots and development directions of cathode materials for lithium-ion capacitors in the future were reviewed in order to provide good electrochemical properties for the next generation of cathode materials for commercial applications.

Titanium carbide (Ti3C2Tx) as one of MXene materials, has unique structure, excellent conductivity, stability and superior electrochemical properties. It is often used as electrode material for supercapacitors. Based on the characteristics of the layered structure of Ti3C2Tx materials, the research progress in Ti3C2Tx based composite materials used for supercapacitor electrode was reviewed, and the structure, properties, preparation and electrochemical performance of Ti3C2Tx materials compounded with various types of materials through different technical means were emphatically described. The reasons for improving the properties of Ti3C2Tx matrix composites were summarized, including increasing the layer spacing, providing more active sites, and improving the toughness. Finally, the future research priorities of Ti3C2Tx matrix composites were pointed out, such as exploring new matrix parent phases, enriching etching methods, improving existing composites, and exploring more and more efficient composites.

As an essential part of nanoparticle‐on‐mirror (NPoM) plasmonic nanocavities, metal mirrors play an important role not only in determining the optical response of the nanocavities but also their application performance. Here the effect of mirror quality on the optical response of nanosphere‐on‐mirror (NSoM) and nanocube‐on‐mirror (NCoM) nanocavities is experimentally studied. Polycrystalline sputtered gold films (SGFs), template‐stripped gold films (TSGFs), and single‐crystalline gold microflakes (GMFs) are investigated and compared. Due to the great improvement in the surface roughness that can minimize fluctuations in the gap morphology, NSoM and NCoM nanocavities formed on smooth TSGFs and GMFs have a better cavity‐to‐cavity homogeneity in the scattering spectrum than those formed on comparably rougher SGFs. In addition, there is an obvious change in the spectral positions of the resonance modes of NSoM and NCoM nanocavities formed on SGFs due to the variation in the gap morphology, which is reproduced very well by theoretical calculations based on measured dielectric functions of the gold films. Finally, due to the reduction in electron scattering losses from SGFs to TSGFs and GMFs, an increase in the quality factors and scattering intensities of the resonance modes is observed for nanocavities formed on the corresponding films. [ABSTRACT FROM AUTHOR]