Developing Polymer Cathode Material for the Chloride Ion Battery.

The chloride ion battery is an attractive rechargeable battery owing to its high theoretical energy density and sustainable components. An important challenge for research and development of chloride ion batteries lies in the innovation of the cathode materials. Here we report a nanostructured chloride ion-doped polymer, polypyrrole chloride, as a new type of potential cathode material for the chloride ion battery. The as-prepared polypyrrole chloride@carbon nanotubes (PPyCl@CNTs) cathode shows a high reversible capacity of 118 mAh g and superior cycling stability. Reversible electrochemical reactions of the PPyCl@CNTs cathode based on the redox reactions of nitrogen species and chloride ion transfer are demonstrated. Our work may guide and offer electrode design principles for accelerating the development of rechargeable batteries with anion transfer.