posted on 2019-01-02, 00:00authored byJin-Yi Li, Ge Li, Juan Zhang, Ya-Xia Yin, Feng-Shu Yue, Quan Xu, Yu-Guo Guo
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–3) but also demonstrate high initial Coulombic
efficiency (90.5%) and cycling stability with areal capacity (4 mA
h cm–2) under a compaction density of 1.3 g cm–3. Furthermore, the full cell assembled with LiNi0.8Co0.1Mn0.1O2 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.