Thin-Walled Carbon Microtubes as High-Capacity and High-Rate Anodes in Lithium-Ion Batteries

In this article, we present a large-area synthesis of carbon microtubes (CMTs) with internal diameters of ∼1.5 μm and wall thicknesses on the order of 50 nm and their lithium ion intercalation and deintercalation properties for the first time. The results show that CMTs exhibit a good capacity retention of 443 mAh g-1 after 20 cycles, higher than the theoretical capacity of graphite and ∼1.5 times higher than the capacity of multi-walled carbon nanotubes at similar conditions. The high capacity retention is attributed mostly to the presence of nanodomains of graphite in the thin walls of the microtubes providing multiple pathways for lithium ion intercalation and the open ends of the CMTs providing additional surface area for intercalation. The CMTs show good rate capability with a capacity retention of 135 mAh g-1 at a current density of 1.5 A g-1.