Rational design of robust nano-Si/graphite nanocomposites anodes with strong interfacial adhesion for high-performance lithium-ion batteries

The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations. However, the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them, thus leading to the deteriorated cycling performance and low Coulombic efficiency. Herein, we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the Si-Ti and Ti-C covalent bonds. The abundant Si-Ti and Ti-C bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force, resulting in the highly stabilized and integrated electrode structure during battery cycling. Consequently, the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%; moreover, a high initial Coulombic efficiency of 90.2% is achieved. Significantly, this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite, which can be applied to other nano-Si based composites anodes. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.