Carbon nanomaterials and their composites for supercapacitors

As a type of energy storage device between traditional capacitors and batteries,the supercapacitor has the advantages of energy saving and environmental protection,high power density,fast charging and discharging speed,long cycle life,and so forth.One of the key factors affecting the performance of supercapacitor is the electrode material.Carbon materials,such as carbon nanotube,graphene,activated carbon,and carbon nanocage,are most widely concerned in the application of supercapacitors.The synergistic effect of composites can often obtain excellent results,which is one of the common strategies to increase the electrochemical performance of supercapacitors.To further improve the performance of binary composites,it is a relatively simple method to increase the components as the“bridge”between the two materials to form the ternary composites.The review mainly introduces the current research progress of supercapacitors with pure carbon nanomaterials and multistage carbon nanostructures(composites)as electrodes.The characteristics and application directions of different pure carbon nanomaterials are introduced in detail.Different ways of multilevel structure(material)composite have their own effects on the development of high-performance supercapacitors.We also highlight the recent advances related to these fields and provide our insight into high-energy supercapacitors.

COMPOSITION DETERMINATION OF BINARY POLYMER MIXTURES BY SIZE EXCLUSION CHROMATOGRAPHY WITH LIGHT SCATTERING DETECTION

Base on the principle of absolute quantification of size exclusion chromatography （SEC）, a light scattering （LS） detector coupled with a concentration detector （refractive index detector） is utilized to determine the compositions of complicated binary mixtures. A theoretical analysis predicts that the response factors for both LS and RI detectors are linear functions with the composition of any specified polymer mixtures in the binary polymer mixtures. Two pairs of complicated binary mixtures were used to test the theory mentioned in the present paper, and the experimental results show an excellent accordance with the theory.

The principle of optimization of binary mobile phase composition of multi-step linear gradient elution

The basic principle of optimal method called “moving overlapping resolution mapping Method” to select the optimal binary mobile phase composition of multi-step linear gradient liquid chromatography is discussed with simultaneously considering effects of position of solute inside the column and mobile phase composition on peak resolution and retention value, then a BASIC program based on this principle is developed in IBM-PC computer. The validities of both principle of optimization and BASIC program are confirmed by separation of samples Containing bile acids and PAHs in RP-HPLC.

Macroscopic electromagnetic synergy network-enhanced N-doped Ni/C gigahertz microwave absorber with regulable microtopography

To achieve excellent electromagnetic wave(EMW)absorption properties,the microstructure design of the absorber is critical.In this work,six kinds of N-Ni/C nanostructures with different morphologies were prepared by one-step hydrothermal method and high temperature carbonization by adjusting the types of nickel salts and reaction solvents.The EMW absorption performance of six different morphologies of N-Ni/C nanostructures was compared and analyzed.Among them,it is found that the nanoflowerlike N-Ni/C composite has excellent dielectric loss and magnetic loss synergistic effect due to its polycrystalline structure,and can obtain excellent EMW absorption performance.The minimum reflection loss value at a thickness of 1.9 mm is-59.56 dB at 16.88 GHz,and the effective absorption bandwidth value reaches 6.0 GHz at a thickness of 2.2 mm.Our research shows that different morphologies and multiple lattice structures of nanostructures with the same composition have a significant influence on EMW absorption performance,which provides new research ideas for developing high-performance EMW absorbing materials.