基于Polymer-S-C/SiO2多层结构大孔电极锂硫离子电池的制备与性能

以新型SiO₂大孔材料为模板，采用原位聚合及真空热解的方法制备出大孔C/SiO₂复合电极，并先后在孔道表面负载单质硫及聚合物膜后得到具有Polymer-S-C/SiO₂多层结构的复合大孔电极。用SEM对电极结构进行表征，并测定了比表面积和负载物的平均厚度；用EIS和充放电测试对电极的电化学性能进行了研究。结果表明：聚合物膜厚度的增加可使电极的交流阻抗迅速增大，同时能明显改善锂硫离子电池的逆循环性，说明聚合物膜的存在能够有效抑制多硫化物中间产物的流失。改变单体的用量可以调控聚合物膜的厚度，当聚合物膜平均厚度为8.0 nm时，锂离子电池的循环性能达到最佳，其首次放电比容量达792 mA·h/g，经过50个循环后，可逆容量仍达到635 mA·h/g。

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.