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

Tin oxide (SnO 2 ) 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)@SnO 2 composite in a graphene coating with novel three-dimensional (3D) porous framework architecture (CNT@SnO 2 @G) as anode for both LIBs and SIBs. The resultant CNT@SnO 2 @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@SnO 2 @G as an advanced anode material for rechargeable LIBs and SIBs.