New binders for Lithium-Sulfur-Batteries

Kurzfassung

New binders for Lithium-Sulfur-Batteries Brigitta Pascucci, Norbert Wagner, K. Andreas Friedrich German Aerospace Center, Institute of Technical Thermodynamics, Stuttgart, Germany A common binder for sulfur-cathodes is PVDF. PVDF requires toxic and/or low-volatile solvents. The drying conditions of such cathodes are either extreme, with loss of active material by sublimation or ambient, which would enhance fabrication cost. Influence of Slurry Composition on Lithium-Sulfur-Battery Performance Only few binder systems have been studied for the application on Li-S batteries. Basically these are PTFE-CMC; PTFE-PVA and PVP [1]; gelatin [2], [3]; Nafion, PANi/CMC and PTFE [4], [5] and SBR/CMC [6]. Due to economically viable application processes, enhanced substrate adhesion, mechanical strength, chemical resistance to battery electrolyte, material and fabrication costs there is a broader variety of suitable binders. For example phenolic-, polyurethane-, epoxy- and silicon-based binders could be studied. To limit the amount of suitable binders, electrochemical stability should be tested first. The electrochemical reduction of polymer chains is often a complicated process with several influencing factors. Not only the thermodynamic behavior of the system is decisive. Kinetic factors, such as the surface of the electrode, the scan rate and the concentration of the solute species influence the outcome. Therefore, in the present work potential binder materials and its electrochemical behaviour are analysed, considering real operation conditions in the electrochemical cell.