Flexible and free-standing bacterial cellulose derived cathode host and separator for lithium-sulfur batteries

This study demonstrates flexible, ultra-high rate, and long cycle life lithium‑sulfur batteries using bacterial cellulose (BC) derived cathode host as well as separator. The work also includes a new strategy to use active sulfur in the form of catholyte added directly to the electrolyte for improved sulfur utilization. The fabricated LiS cell with carbonized bacterial cellulose (CBC) as a cathode host and BC as a separator (CBC@BC) delivers an impressive capacity of 740 mAh g^-1 at 1C. It retains a capacity of 310 mAh g^-1 even at an ultra-high rate of 4C. To have commercial adoption of CBC@BC, we tested LiS cells with a high areal loading of 5 mg cm^-2. The cell shows promising electrochemical performance for 500 cycles with a capacity retention of 82 %. Furthermore, first-principle calculations are performed to understand the interaction of soluble lithium-polysulfides with bacterial cellulose-derived material.