Effect of nitrogen-containing polymer wrapped around carbon nanotubes for Li–O2 battery cathode

Abstract

In the development of lithium (Li)–oxygen (O2) rechargeable batteries, the improvement of the rechargeability is one of the key issues to be solved. Herein, a novel strategy to solve this issue is explored using polymer-wrapped single-walled carbon nanotubes (SWCNTs) as the cathode material. Poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI), employed as the wrapping polymer of the SWCNTs, served to coordinate Li ions and to facilitate a favorable deposition of the discharge products on the SWCNTs during the discharge reaction at the cell cathode. As a result, the rechargeability of the cell (SWCNT/PyPBI-cell) was improved compared to the cell having nonwrapped SWCNTs as the cathode (SWCNT-cell). Single-walled carbon nanotubes (SWCNTs) wrapped by poly[2,2’-(2,6-pyridine)-5,5’-bibenzimidazole] (PyPBI) was used for a cathode material of lithium (Li)-oxygen (O2) rechargeable battery. Compared to the Li–O2 cell using nonwrapped SWCNTs, the cell using PyPBI-wrapped SWCNTs showed improved rechargeability during charge–discharge cycles. It was revealed that PyPBI layer facilitated the homogeneous deposition of the discharge products, resulting the smooth reaction during the cycles. The coordination of Li ion onto PyPBI surface might be the key mechanism to realize the homogeneous deposition.