Preparation and performance of lithium-sulfur batteries based on multilayer structure in Polymer-S-C/SiO₂ macroporous electrodes

The macroporous conducting C/SiO₂ composite electrode was prepared in-situ polymerization and vacuum pyrolysis in a novel SiO₂ macroporous template, followed by loading the elemental sulfur and the polymer film on the channel surface to obtain the Polymer-S-C/SiO₂ composite macroporous electrode with multilayer structure. The structures of Polymer-S-C/SiO₂ electrodes were characterized by SEM, and the specific surface area and average thickness of loads were also measured. The electrochemical performances were studied by electrochemical charge-discharge experiments and impedance spectroscopy. The results show that the alternating current impedance of electrode increases rapidly and the reverse cycle performance of lithium ion batteries are improved obviously when the thickness of the polymer film increases, which shows that the existence of the polymer film can effectively inhibit the loss of polysulfide intermediate. The thickness of the polymer film can be adjusted by changing the dosage of the monomer. When the average thickness of the polymer film is 8.0 nm, the lithium ion battery exhibits the first discharge specific capacity of 792 mA·h/g, and it remains 635 mA·h/g after 50 cycles, which shows the best effects.