Poly(ionic liquid) ABC triblock and ABCBA pentablock terpolymer electrolytes for lithium metal batteries

Abstract

In this study, poly(ionic liquid) (PIL) ABC triblock and ABCBA pentablock terpolymers (PILTTP and PILPTP, respectively) were synthesized to investigate the impact of chain architecture (ABC versus ABCBA) on properties. Specifically, the morphology, ionic conductivity, mechanical properties, electrochemical stability, and lithium metal battery performance of the PILTTP and PILPTP as ternary solid polymer electrolytes (SPEs) containing corresponding lithium salt and ionic liquid (IL) (at various IL concentrations) were measured. Interestingly, the PILPTP SPEs show one order of magnitude higher Young's modulus compared to the PILTTP at the same IL concentration due to bridged conformations and interlocked entanglements of the PILPTP. The improved mechanical properties of the PILPTP SPE lead to enhanced electrochemical stability and stable battery performance over 50 cycles at room temperature, exhibiting dendrite suppressing ability. This study highlights the importance of the symmetric ABCBA structure of PIL multiblock polymers on cycling stability for solid-state lithium metal batteries.