Poly(ionic liquid) binders as Li+ conducting mediators for enhanced electrochemical performance

Abstract

A series of poly(ionic liquid)s (PILs) were used as binders for lithium-ion battery (LIB) with a LiFePO₄ cathode to explore their role and benefits in a model electrochemical energy storage system. The PILs are imidazolium-based and bear different main chain structures and alkyl substituents. The results nicely show that PILs both improve the cycling stability and specific capacity. When carefully designed, they especially exhibited a usually high electrochemical stability against oxidative conditions (=4.0 vs. Li/Li⁺). It is found that the PIL binders together with carbon additive form very effective Li⁺ and electron conducting pathways in the electrode. These finding illustrate that binder with carefully designed chemical structures can have a high potential to improve the electrochemical performance even of current rechargeable battery systems. A better Li⁺ and electron conduction is however of general importance for a wide spectrum of electrochemical devices.