Extrusion of Polymer Blend Electrolytes for Solid-State Lithium Batteries: A Study of Polar Functional Groups

Polymer blends have emerged as promising candidates for solid polymer electrolytes (SPEs) in lithium batteries as dry blending polymers allow the benefits of each polymer to be easily combined. However, mixing polymers with different ionic transport properties can complicate the understanding of ion transport mechanisms in the blended material. Indeed, in polymer blends, the contribution of each component to ionic transport differs considerably. This paper presents a systematic study of the salt dissociation ability of polar functional groups in various polymer blends. The blends presented here were obtained through dry processing, which allows the effect of solvents on salt/polymer interactions to be neglected. The studied polymers, which are commonly used to produce SPEs, were selected based on their polar functional groups: PEO (ether), PCL (ester), PPC (carbonate), PVA (alcohol), HNBR (nitrile), and PVP (amide). Given the combined EDX, 7Li NMR, and FTIR results, a ranking of the lithium salt solvating ability of these polymers as a function of their polar functional groups has been made. This study also provides valuable information that contributes to increase comprehension of ionic transport in SPEs.