Three-dimensional porous graphene-encapsulated CNT@SnO₂ composite for high-performance lithium and sodium storage

Graphical abstract: Herein, a novel three-dimensional (3D) porous graphene-encapsulated SnO₂@CNT framework (CNT@SnO₂@G) composite was prepared using a facile two-step hydrothermal method. The resultant CNT@SnO₂@G anode delivers outstanding lithium and sodium storage performance with remarkable cycling stability and excellent rate capability, which provide a promising potential toward advanced SnO₂ anode materials for LIBs and SIBs. - Highlights: • Novel CNT@SnO₂@G composite was prepared by a facile two-step hydrothermal method. • The composite encapsulates core–shell structured CNT@SnO₂ in a graphene coating. • The resultant composite delivers outstanding lithium and sodium storage performance. - Abstract: Tin oxide (SnO₂) is regarded as a promising anode material for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to its large theoretical capacity. However, poor electrical conductivity and the weak cyclability resulted from dramatic volume expansion upon cycling process still hinder its practical application. Herein, we report a facile two-step hydrothermal route to encapsulate core–shell structured carbon nanotube (CNT)@SnO₂ composite in a graphene coating with novel three-dimensional (3D) porous framework architecture (CNT@SnO₂@G) as anode for both LIBs and SIBs. The resultant CNT@SnO₂@G electrode suggests outstanding lithium and sodium storage performance with large specific capacity, remarkable cycling stability and excellent rate capability. For LIBs, it delivers a high initial discharge capacity of 1400 mAh g⁻¹ at 100 mA g⁻¹, improved reversible capacity of 947 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹, and enhanced rate capability of 281 mAh g⁻¹ at 3000 mA g⁻¹. In addition, sodium storage testing suggests that a high discharge capacity of 323 mAh g⁻¹ after 100 cycles at 25 mA g⁻¹ was achieved. The present unique structural design associated with the remarkable lithium and sodium storage performance ensures CNT@SnO₂@G as an advanced anode material for rechargeable LIBs and SIBs.