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A novel carbonized phenolic formaldehyde resin (PF) resin-coated Ni foam was used as an interlayer for brazing carbon fiber reinforced carbon composites (C/C) and Nb using a Ti–Ni filler. At first, uniformly distributed carbonaceous laminae with different mass fractions on the Ni foam surface were acquired after the carbonization process by controlling the concentration of the PF solution. Afterwards, the obtained carbonaceous laminae covered Ni foam composite (C-Nif) was applied as an interlayer for brazing C/C and Nb via an assembly of C/C/Ti foil/Ni foil/C-Nif interlayer/Ti foil/Nb. The morphologies and microstructures of the carbonization product and the interfacial microstructures of the joints were investigated. The brazing mechanism has been elaborated in detail. With the help of the interconnected porous structure of the Ni foam, the distribution of the in-situ formed (Ti,Nb)2Ni particles, (Ti,Nb)C ring reinforcements as well as the Nb solid solution were uniformly obtained throughout the brazing seam. As a result, the joint residual stress was effectively released and consequently, the joint shear strength at elevated temperature (1000 °C) reached up to 33 MPa, which is 4.5 times higher than the directly brazed joint without an interlayer.

Increasing the electrochemical stability window and working temperature range of supercapacitor aqueous electrolyte is the major task in order to advance aqueous electrolyte-based supercapacitors. Here, a supramolecular induced new electrolyte of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in dimethyl sulfoxide (DMSO) and water co-solvent system is proposed. Adjusting the coordination structure among LiTFSI, DMSO, and water in the electrolyte via supramolecular interactions results in its high ionic conductivity, low viscosity, wide electrochemical stability window, and large working temperature range. The new electrolyte-based supercapacitors can work in 2.40 V working potential and 130 °C working-temperature range from −40 to 90 °C. The devices exhibit good electrochemical performances, especially the energy density over 21 Wh kg−1, which is much higher than that with traditional aqueous electrolytes (

It is found that crystalline nanoporous Ge can only partially store sodium, with amorphous NaxGe as the sodiation product. Electrochemical dilatometry techniques were used to measure the corresponding (de)sodiation-induced strains. The capacity and strain amplitude were found to exhibit the same decay trend during long-term cycling, which is expected since the capacity fades because of the volume changes arising during cycling. However, viewed from a different perspective, the similarity between capacity fading and strain decay suggests that one way to mitigate this capacity fading might be by preventing the initial strain from decaying, instead of getting rid of this strain.

Brazing C/C composites to Nb is often associated with high residual stress in this research, which results in low-strength joints. To overcome this problem, here we report a novel type of three-dimensional graphene-reinforced Cu foam (G-Cu foam) composite fabricated using chemical vapor deposition. This G-Cu foam was used as an interlayer for brazing C/C composite and Nb. Results show that high-quality graphene was evenly introduced in the brazing seam without agglomeration with the help of Cu foam substrate, which has a porous structure with an interconnected 3D scaffold. Moreover, wetting analyses revealed that the obtained graphene played a key role in retarding the metal atoms diffusion and consequently impeding the collapse of the Cu foam skeleton at brazing temperature. Furthermore, the extremely low coefficient of thermal expansion (CTE) of graphene and the good plastic deformation capacity of Cu foam are both conducive to reducing the thermal residual stress during the cooling process. By exerting the synergistic strengthening effect of both graphene and Cu foam, the brazed joint was effectively enhanced. The average shear strength of the joint brazed with G-Cu foam interlayer is ∼43 MPa.