Controllable synthesis of SnO2@C yolk–shell nanospheres as a high-performance anode material for lithium ion batteries

Abstract

In this work, we report a facile synthesis of uniform SnO₂@C yolk–shell nanospheres as high-performance anode materials for lithium ion batteries (LIBs). The yolk–shell structured SnO₂@C nanospheres were fabricated through a two-step sol–gel coating process by using tetraethyl orthosilicate (TEOS) and resorcinol–formaldehyde (RF) as precursors, where the silica interlayer not only acts as a template to produce the void space, but also promotes the coating of the RF layer. The synthesis is easy to operate and allows tailoring the carbon shell thickness and void space size. The resultant SnO₂@C yolk–shell nanospheres possess a hollow highly crystalline SnO₂ core (280–380 nm), tailored carbon shell thickness (15–25 nm) and a large void space size (100–160 nm), a high surface area (∼205 m² g⁻¹), a large pore volume (∼0.25 cm³ g⁻¹), as well as a high SnO₂ content (77 wt%). When evaluated as an anode of LIBs, the materials manifest superior electrochemical performance with a high lithium storage capability (2190 mA h g⁻¹ in initial discharge capacity; >950 mA h g⁻¹ in the first 10 cycles), a good cycling performance and an excellent rate capability.