Microstructural and Dynamical Characterization of Polymer Electrolytes for Li-ion Batteries Using Advanced Solid-State NMR Techniques 

Isha Isha (Indian Institute of Science, India)

Abstract: Solid-state lithium-ion batteries (SSLBs) with lithium metal anodes present significant advantages over conventional liquid electrolyte-based lithium-ion batteries (LIBs), including higher energy densities and improved safety. The flammability of liquid electrolytes and the formation of dendrites at the electrodes are critical safety concerns in traditional LIBs. Furthermore, the energy density of conventional LIBs (200–300 Wh kg⁻¹) is insufficient for long-distance applications in battery-powered devices, and their operational temperature range is limited to -20°C to 60°C.
Implementing solid electrolytes (SEs) offers a promising solution to these challenges. Solid polymer electrolytes (SPEs) exhibit superior mechanical properties and enhanced safety features. However, the primary limitation of SPEs is their low ionic conductivity, typically around 10-4 Scm-1 under ambient conditions, which remains a significant obstacle to their widespread adoption. Understanding the mechanism of conductivity is a crucial step. Our Research mainly focuses on understanding the conductivity mechanism of the polymer electrolytes. Ionic Conductivity depends on the structure and the dynamics of the polymer backbone, and the Solid-State NMR is the only technique that can probe both the local structure and the dynamics. The microscopic properties of the polymers, such as the local structures, phases, and dynamics significantly influence macroscopic conductivity. Understanding the structure-property relationships is crucial to design SPE(s). SS NMR spectroscopy allows non–invasive characterization with site-specific local structural and dynamical details of materials regardless of their crystallinity. The NMR interactions are susceptible to the local structures and dynamics that have been used to gain insight into ion–dynamics mechanism in SPE(s).