Supercapacitors are widely used in China due to their high energy storage efficiency, long cycle life, high power density and low maintenance cost. This review compares the differences of different types of supercapacitors and the developing trend of electrochemical hybrid energy storage technology. It gives an overview of the application status of supercapacitors in China’s smart grid and Energy Internet in detail. Some strategies and constructive suggestions are put forward to solve the existing problems. With the improvement of the grid-connected capacity of new energy power generation during the 14th Five-year Period of China, the supercapacitor market in China will usher in a good development opportunity. The role of the supercapacitor in achieving carbon peak carbon neutralization is prospected.

Cs ₂ SnI ₆ is a variant on tin-iodide solution-processable materials and may lead to a lead-free material for use in next-generation photovoltaic cells and other optoelectronics. So far, only a few studies have been conducted where shape and geometry control of Cs ₂ SnI ₆ nanocrystals is demonstrated. Here we report a general approach to directly synthesize Cs ₂ SnI ₆ of two-dimensional (2D) layered nanoplatelets as well as three-dimensional (3D) nanocrystals. The shape of Cs ₂ SnI ₆ nanocrystals could be engineered into 3D nanoparticles and different 2D nanoplatelets with well-defined morphology by choosing different organic acid and amine ligands via a hot injection process. Moreover, the thickness of layered 2D nanoplatelets could be adjusted by changing the amount of Cs-oleate present during the synthesis. The photoluminescence emission peaks changed from 643 to 742 nm based on nanomaterial shape. Our method provides a facile and versatile route to rationally control the shape of the Cs ₂ SnI ₆ nanocrystals, which will create opportunities for applications in lead-free optoelectronics.

In this work, the O-PAM-LiCl hydrogel was prepared by free radical copolymerization of dimethyl sulfoxide and acrylamide, LiCl as filler, which exhibited highly recoverable stretchable property, excellent adhesive and self-healing capacity. O-PAM-LiCl hydrogel with good recovery tensile properties, good adhesion and self-healing ability (healing within 30 mins) was selected as the main research object. The results show that O-PAM-LiCl hydrogel electrolytes have excellent ionic conductivity of 1.8 S m^-1. The as-synthesized O-PAM-LiCl hydrogel electrolyte with CNTs-Ni electrodes shows a specific capacitance of 58.12 F g^-1 at 50 mV s^-1 in 3 g LiCl concentrations. After 2000 cycles, the capacitance retention is retained at 71.98% at a current density of 1 A g^-1. After assembling the supercapacitor using carbon nanotube electrode material, it exhibits excellent electrochemical performance upon evaluation. The introduction of LiCl resulted in the "salting in" effect, which partially destroyed the original hydrogen bonds in the hydrogels and endowed O-PAM-LiCl hydrogels with extremely high transparency and water retention properties. It was observed by SEM that the O-PAM-LiCl have loose porous structure. Furthermore, this composite hydrogel demonstrates significant potential for development.