Ge Mingzheng, Tang Yuxin, Malyi Oleksandr I, Zhang Yanyan, Zhu Zhiqiang, Lv Zhisheng, Ge Xiang, Xia Huarong, Huang Jianying, Lai Yuekun, Chen Xiaodong
National Engineering Research Center of Chemical Fertilizer Catalyst (NERC-CFC), College of Chemical Engineering, Fuzhou University, Fuzhou, 350116, P. R. China.
National & Local Joint Engineering Research Center of Technical Fiber Composites for Safety and Health, School of Textile and Clothing, Nantong University, Nantong, 226019, P. R. China.
Small. 2020 Jul;16(30):e2002094. doi: 10.1002/smll.202002094. Epub 2020 Jun 11.
Silicon anode with extremely high theoretical specific capacity (≈4200 mAh g ), experiences huge volume changes during Li-ion insertion and extraction, causing mechanical fracture of Si particles and the growth of a solid-electrolyte interface (SEI), which results in a rapid capacity fading of Si electrodes. Herein, a mechanically reinforced localized structure is designed for carbon-coated Si nanoparticles (C@Si) via elongated TiO nanotubes networks toward stabilizing Si electrode via alleviating mechanical strain and stabilizing the SEI layer. Benefited from the rational localized structure design, the carbon-coated Si nanoparticles/TiO nanotubes composited electrode (C@Si/TiNT) exhibits an ideal electrode thickness swelling, which is lower than 1% after the first cycle and increases to about 6.6% even after 1600 cycles. While for traditional C@Si/carbon nanotube composited electrode, the initial swelling ratio is about 16.7% and reaches ≈190% after 1600 cycles. As a result, the C@Si/TiNT electrode exhibits an outstanding capacity of 1510 mAh g at 0.1 A g with high rate capability and long-time cycling performance with 95% capacity retention after 1600 cycles. The rational design on mechanically reinforced localized structure for silicon electrode will provide a versatile platform to solve the current bottlenecks for other alloyed-type electrode materials with large volume expansion toward practical applications.
具有极高理论比容量（约4200 mAh g）的硅阳极在锂离子嵌入和脱出过程中会经历巨大的体积变化，导致硅颗粒发生机械断裂以及固体电解质界面（SEI）的生长，这使得硅电极的容量迅速衰减。在此，通过细长的TiO纳米管网络为碳包覆硅纳米颗粒（C@Si）设计了一种机械增强的局部结构，以通过减轻机械应变和稳定SEI层来稳定硅电极。受益于合理的局部结构设计，碳包覆硅纳米颗粒/TiO纳米管复合电极（C@Si/TiNT）表现出理想的电极厚度膨胀，首次循环后低于1%，即使在1600次循环后也增加到约6.6%。而对于传统的C@Si/碳纳米管复合电极，初始膨胀率约为16.7%，1600次循环后达到约190%。结果，C@Si/TiNT电极在0.1 A g下表现出1510 mAh g的出色容量，具有高倍率性能和长时间循环性能，1600次循环后容量保持率为95%。对硅电极机械增强局部结构的合理设计将为解决其他具有大体积膨胀的合金型电极材料在实际应用中的当前瓶颈提供一个通用平台。
