The end-cap removal of carbon nanotubes (CNTs) refers to the structural modification method that makes inner-core spaces and voids between walls accessible. Specifically, the accommodation of alkali metal cations in those hidden surfaces for electrochemical energy storage has been a challenging task. Here we present open-ended vertically aligned CNTs (VA-CNTs) as an ideal structure for Li+ accommodation, which were produced by chemical vapor deposition, followed by CF4 reactive ion etching. A model study suggests a link between Li+ capacity and the surface area, more specifically, allows us to estimate the amount of additional Li+ accommodation, which is 2.3 times increased after end-cap removal. The relatively high capacity (889 mAh/g) has confirmed that open-ended VA-CNTs are highly active for Li+ intercalation as well as exposing interior surfaces, which can be compared to the control (338 mAh/g). The microstructural change observation combined with spectroscopic studies reveals that poor Li+ reversibi...