Ambient‐Temperature Sodium–Sulfur Batteries with a Sodiated Nafion Membrane and a Carbon Nanofiber‐Activated Carbon Composite Electrode

DOI: 10.1002/aenm.201500350 also been studied with Li–S battery systems. [ 8 ] In light of the above efforts, herein, we report an alternative approach to suppress the sodium polysulfi de shuttling by using a nonporous sodiated Nafi on membrane as the Na-ion exchange separator. Generally, in an RT Na–S battery system, the utilization of active cathode material is directly dependent on the accommodation ability of the conductive cathode matrix due to the insulating nature of both the fully charged (elemental sulfur) and the fully discharged (sodium sulfi de) products and the soluble nature of the intermediate sodium polysulfi des produced during charge/discharge. [ 5 ] In this regard, porous carbon materials with high surface area are preferred for enhancing sulfur utilization. Activated carbon materials usually possess high porosity to provide extremely high surface area for chemical or electrochemical reactions. However, preparation of an electrode with the activated carbon materials requires the use of nonconductive, nonactive binder materials to maintain an integrated structure of the electrode. We have previously presented the use of a multiwall carbon nanotube (MWCNT) paper as a 3D electrode for the Na/dissolved polysulfi de battery system. [ 7f ]