LAUSR

Abstract Heteroatom doped porous carbon nanotubes (CNTs) have been widely used as sulfur host and stable polysulfide reservoir in the Li–S batteries. In the present work, the effect of the pore size in the porous CNTs on the battery performance of the CNTs-based sulfur cathodes was investigated by comparing the electrochemical performance of the N, O-doped porous CNTs, which were designed by the carbonization of the PPy nanotubes as precursor with different amounts of KOH as activating agent. The results showed that sulfur could completely fill the mesopores and hollow cavity of the mesoporous carbon nanotubes (PNCT-2) prepared with severe KOH activation, with theoretical calculated sulfur content. In comparison with the S-PCNT-1 cathode with sulfur coated onto the outer surface of the microporous carbon nanotubes (PNCT-1), the S-PCNT-2 cathode possessed higher specific capacity and rate capacity, as well as better cyclic life. Such features are ascribed to the large specific surface area and the appropriate pore size of the PCNT-2, which provides an efficient diffusion path for the sulfur and electrolyte as well as polysulfide trap suppressing the “shuttle effect” efficiently.