Chinese Academy of Sciences (CAS) Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS) , Institute of Chemistry, CAS , Beijing 100190 , P. R. China.
University of Chinese Academy of Sciences , Beijing 100049 , P. R. China.
ACS Appl Mater Interfaces. 2019 Jan 30;11(4):4057-4064. doi: 10.1021/acsami.8b20213. Epub 2019 Jan 15.
Si has been recognized as a next-generation anode alternative to graphite for high-energy-density lithium-ion batteries. However, the most intractable problem of previous Si-based anodes is the relatively low compressive strength of particles because of excess voids and porous structures, thus leading to poor structural integrity and electrochemical performance under high pressure of the rolling procedure in practical application. Therefore, a rational design of robust Si/C microspheres with a compact nano/microstructure is an effective strategy to address the above-mentioned issues. In this ingenious structure, Si nanoparticles are homogeneously dispersed and anchored on flake graphite and then the composites self-assemble into microspheres via polycondensation and surface tension of pitch under high temperature and high pressure. Benefitting from this innovative approach and rational design, the obtained robust Si/C microspheres not only present high compressive property and high tap density (1.0 g cm) but also demonstrate high initial Coulombic efficiency (90.5%) and cycling stability with areal capacity (4 mA h cm) under a compaction density of 1.3 g cm. Furthermore, the full cell assembled with LiNiCoMnO and the resultant Si/C microsphere anode also displays good cycling performance and rate capabilities. Owing to these aspects, the proposed rational design of encapsulating Si nanoparticles in high-tap-density microspheres could be extended to load other nanomaterials for advanced batteries.
硅已被公认为下一代石墨型高能锂离子电池的阳极替代材料。然而，以前的硅基阳极最棘手的问题是由于过多的空隙和多孔结构，颗粒的抗压强度相对较低，从而导致在实际应用中压延过程中的高压下较差的结构完整性和电化学性能。因此，合理设计具有紧凑纳米/微观结构的坚固 Si/C 微球是解决上述问题的有效策略。在这种巧妙的结构中，Si 纳米颗粒均匀分散并锚定在鳞片石墨上，然后复合材料通过高温高压下的缩聚和沥青的表面张力自组装成微球。得益于这种创新方法和合理设计，所获得的坚固 Si/C 微球不仅具有高抗压性和高密度（1.0 g cm），而且在压实密度为 1.3 g cm 时，具有高初始库仑效率（90.5%）和循环稳定性（面容量为 4 mA h cm）。此外，由 LiNiCoMnO 和所得的 Si/C 微球阳极组装的全电池也表现出良好的循环性能和倍率性能。由于这些方面，将 Si 纳米颗粒封装在高振实密度微球中的合理设计可以扩展到负载其他纳米材料的先进电池中。
