Preparation and electrochemical performance of SnO 2@carbon nanotube core–shell structure composites as anode material for lithium-ion batteries

Abstract

Carbon nanotube-encapsulated SnO 2 (SnO 2@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 SnO 2 is filled into the interior hollow core of CNTs and exists as small nanoparticles with diameter of about 6 nm. The SnO 2@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 (0.1 C), the sample containing wt. 65% of SnO 2 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 2.0 C), the composite electrode still exhibits capacity retention of 563, 507 and 380 mAh g −1, respectively. The capacity retention of our SnO 2@CNT composites is much higher than previously reported values for a SnO 2/CNT composite with the same filling yield. The excellent lithium storage and rate capacity performance of SnO 2@CNT core–shell composites make it a promising anode material for lithium-ion batteries.