Versatile Mixed Ionic-Electronic Conducting Binders for High-Power, High-Energy Batteries

Abstract

The increasingly extensive use of Lithium-Ion Batteries (LIBs) requires further optimization of the devices to make use of their maximum practical specific capacity. Although the binder occupies a small fraction of the electrode mass, it is one of the most crucial components to achieve improved cell performance and cycle life. Conducting polymers such as PEDOT:PSS have been already studied as binders for high-performance lithium-ion batteries (LIBs) but without addressing the structure-property relationships of the binder in the electrode. Herein, we develop mixed ionic-electronic conducting (MIEC) binders based on PEDOT:PSS (PPSS) and PEDOT:PDADMA-TFSI (PPTFSI) for Li-ion cathodes and we compare their performances with conventional formulations containing PVDF binder in Li||LFP cells. Furthermore, the influence of electrode formulations, including addition of conducting carbon (C), to balance the required porosity; and the Organic Ionic Plastic Cristal (OIPC) N-ethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide) (C2mpyrTFSI, O), to promote a synergistic effect of ionic and electronic conductivity enhancement; are analyzed. Finally, the versatility of these proposed binders is demonstrated with graphite||LFP full cells, high-voltage active material (NMC 111) as well as different electrolyte types (from liquid 1M LiTFSI in DOL/DME and ionic liquid based, to solid state membranes) showing the same trends, with improved performances in comparison with conventional formulations.