A facile assembly of SnO2 nanoparticles and moderately exfoliated graphite for advanced lithium-ion battery anode

High-capacity SnO2 is considered as one of the most potential anode candidates but suffers from its low coulombic efficiency, low conductivity, and large volume expansion. To solve these bottlenecks, we designed an assembly of nano-SnO2 and moderately exfoliated graphite (MEG) to form a hybrid of SnO2 and MEG coated with amorphous carbon (SnO2/MEG@C). In the liquid phase system at room temperature, the moderate exfoliation of graphite and the SnO2 embedded into the MEG interlayer were realized at the same time. Graphite expansion generates plenty of parallel lamellas, which accommodates the SnO2 nanoparticles between these lamellas and prevents their agglomeration in confined spaces. The MEG as flexible and conductive support can attach SnO2 nanoparticles tightly, which enhance the electron transfer, and also can hinder the agglomeration of SnO2. Meanwhile, the carbon coating can effectively adapt to the volume changes of SnO2 nanoparticles. Moreover, the interaction between the MEG and carbon coating can form a physical barrier that effectively hinders Sn coarsening, which maintains the rapid mutual diffusion kinetics between nano Sn/Li2O interfaces, leading to the high-efficiency conversion reaction of SnO2 in the composite and excellent reversibility and cyclicity. The SnO2/ MEG@C electrode exhibits a high capacity of 691.4 mAh g−1 after 900 cycles at 1.0 A g−1. The method in this work can guide the design and synthesis of materials with high capacity and adaptive volume expansion.