Preparation and electrochemical performance of SnO2@carbon nanotube core–shell structure composites as anode material for lithium-ion batteries

Carbon nanotube-encapsulated SnO2 (SnO2@CNT) core–shell composite anode materials are prepared by chemical activation of carbon nanotubes (CNTs) and wet chemical filling. The results of X-ray diffraction and transmission electron microscopy measurements indicate that SnO2 is filled into the interior hollow core of CNTs and exists as small nanoparticles with diameter of about 6 nm. The SnO2@CNT composites exhibit enhanced electrochemical performance at various current densities when used as the anode material for lithium-ion batteries. At 0.2 mA cm−2 (0.1C), the sample containing wt. 65% of SnO2 displays a reversible specific capacity of 829.5 mAh g−1 and maintains 627.8 mAh g−1 after 50 cycles. When the current density is 1.0, 2.0, and 4.0 mA cm−2 (about 0.5, 1.0, and 2.0C), the composite electrode still exhibits capacity retention of 563, 507 and 380 mAh g−1, respectively. The capacity retention of our SnO2@CNT composites is much higher than previously reported values for a SnO2/CNT composite with the same filling yield. The excellent lithium storage and rate capacity performance of SnO2@CNT core–shell composites make it a promising anode material for lithium-ion batteries.

► Carbon nanotube-encapsulated SnO2 core–shell composites are prepared by simple method. ► The etching defects on carbon nanotubes are helpful to increase SnO2 filling yield. ► Selective cleaning ensures SnO2 only filled into the interior hollow cores of CNTs. ► The composites exhibit good electrochemical performance at high current densities.