NMR studies of lithium and sodium battery electrolytes

Abstract

This review focuses on the application of nuclear magnetic resonance (NMR) spectroscopy in the study of lithium and sodium battery electrolytes. Lithium-ion batteries are widely used in electronic devices, electric vehicles, and renewable energy systems due to their high energy density, long cycle life, and low self-discharge rate. The sodium analog is still in the research phase, but has significant potential for future development. In both cases, the electrolyte plays a critical role in the performance and safety of these batteries. NMR spectroscopy provides a non-invasive and non-destructive method for investigating the structure, dynamics, and interactions of the electrolyte components, including the salts, solvents, and additives, at the molecular level. This work attempts to give a nearly comprehensive overview of the ways that NMR spectroscopy, both liquid and solid state, has been used in past and present studies of various electrolyte systems, including liquid, gel, and solid-state electrolytes, and highlights the insights gained from these studies into the fundamental mechanisms of ion transport, electrolyte stability, and electrode-electrolyte interfaces, including interphase formation and surface microstructure growth. Overviews of the NMR methods used and of the materials covered are presented in the first two chapters. The rest of the review is divided into chapters based on the types of electrolyte materials studied, and discusses representative examples of the types of insights that NMR can provide.