Sword-sheath structured CNT@SnO ₂ @CNx boosting the electrochemical performance in lithium-ion batteries

The practical application of tin dioxide (SnO₂) in lithium-ion batteries (LIBs) has been significantly hindered by its inherently low electrical conductivity and substantial structural degradation during repeated charge/discharge cycles. To overcome these challenges, we designed a novel sword-sheath structured CNT@SnO₂@CNₓ composite, featuring a nitrogen-doped carbon outer layer, an internal cavity for buffering volume changes, and a highly conductive carbon nanotube (CNT) core. This unique architecture effectively mitigates the aforementioned issues, enabling exceptional cycling stability (1087.5 mAh g -1 at 0.1 A g -1 after 100 cycles) and outstanding rate capability (533.6 mAh g -1 at 5 A g -1 ). The enhanced electrochemical performance stems from the synergistic effects of the structure: the void space between SnO₂ and the CNT accommodates volume expansion, while the conformal carbon coating preserves structural integrity throughout cycling.