Double-walled carbon nanotubes are seamless hollow nanotubes formed by the curling of two layers of graphene sheets. Its structure is between single-walled and multi-walled carbon nanotubes and has most of their properties.

DWNT can be used as a gas sensor, as a sensitive material to detect gases such as H2, NH3, NO2 or O2, etc., used in demanding technical applications, such as field emission displays and photovoltaic devices.

Due to the higher electronic conductivity, carbon nanotubes can act as a conductive agent in lithium batteries, which is equivalent to the role of "conductors" in the lithium battery conductive network. The carbon storage capacity of carbon nanotubes is much greater than that of traditional carbon materials such as natural graphite, artificial graphite and amorphous carbon. Therefore, the use of carbon nanotubes as a lithium battery conductive agent can greatly increase the capacity and cycle life of lithium batteries. , Carbon nanotubes have an electric double layer effect, which is conducive to improving the battery's large rate charge and discharge performance. At the same time, the amount of carbon nanotubes used in lithium batteries is small, which can reduce the content of conductive agents in lithium batteries. Its good thermal conductivity is also conducive to heat dissipation during battery charging and discharging.