Shao Jin, Yang Yi, Zhang Xiaoyan, Shen Liming, Bao Ningzhong
State Key Laboratory of Material-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009, China.
Zigong Innovation Center of Zhejiang University, Zhejiang University, Zigong 643000, China.
Materials (Basel). 2021 May 26;14(11):2836. doi: 10.3390/ma14112836.
In this study, we have successfully prepared a free-standing Si/void/rGO yolk-shell structured electrode via the electrostatic self-assembly using protonated chitosan. When graphene oxide (GO) is dispersed in water, its carboxyl and hydroxyl groups on the surface are ionized, resulting in the high electronegativity of GO. Meanwhile, chitosan monomer contains -NH and -OH groups, forming highly electropositive protonated chitosan in acidic medium. During the electrostatic interaction between GO and chitosan, which results in a rapid coagulation phenomenon, Si/SiO nanoparticles dispersed in GO can be uniformly encapsulated between GO sheets. The free-standing Si/void/rGO film can be obtained by freeze-drying, high-pressure compression, thermal reduction and HF etching technology. Our investigation shows that after 200 charge/discharge cycles at the current density of 200 mA·g, the specific discharge capacity of the free-standing electrode remains at 1129.2 mAh·g. When the current density is increased to 4000 mA·g, the electrode still has a specific capacity of 469.2 mAh·g, showing good rate performance. This free-standing electrode with a yolk-shell structure shows potential applications in the field of flexible lithium-ion batteries.
在本研究中，我们通过使用质子化壳聚糖的静电自组装成功制备了一种独立式Si/void/rGO蛋黄壳结构电极。当氧化石墨烯（GO）分散在水中时，其表面的羧基和羟基会发生电离，导致GO具有高电负性。同时，壳聚糖单体含有-NH和-OH基团，在酸性介质中形成高度带正电的质子化壳聚糖。在GO与壳聚糖之间的静电相互作用导致快速凝聚现象的过程中，分散在GO中的Si/SiO纳米颗粒可以均匀地包裹在GO片层之间。通过冷冻干燥、高压压缩、热还原和HF蚀刻技术可以获得独立式Si/void/rGO薄膜。我们的研究表明，在200 mA·g的电流密度下进行200次充放电循环后，独立式电极的比放电容量保持在1129.2 mAh·g。当电流密度增加到4000 mA·g时，该电极仍具有469.2 mAh·g的比容量，显示出良好的倍率性能。这种具有蛋黄壳结构的独立式电极在柔性锂离子电池领域显示出潜在的应用前景。
