Investigation Into the Electrochemical Performance of Micron‐ and Nanosized Tin in Diglyme and Carbonate Electrolytes in Sodium Ion Batteries

ABSTRACT The electrochemical performance of tin (Sn) electrodes for sodium ion batteries (NIBs) is investigated, focusing on the challenges of severe volume expansion during cycling and electrolyte incompatibility. Micron‐sized Sn delivers better cycle life than nanoparticles; however, limited research exists on the combined effects of particle size and electrolyte compatibility. In‐house synthesized Sn particles (50 nm–1 µm) and commercial micron‐sized Sn (5–35 µm), using 1 m NaPF 6 in both EC:DEC (carbonate‐based) and in diglyme electrolytes are compared. The diglyme‐based electrolyte demonstrates stable cycling over 150 cycles despite a theoretical volume expansion of up to 430% upon sodiation, which results from the formation of a robust and flexible solid–electrolyte interphase (SEI) that maintains electrode integrity. In contrast, carbonate‐based electrolytes exhibit rapid capacity fading due to catalytic decomposition of the solvent on Sn nanoparticles. The findings highlight the critical influence of electrolyte composition and particle size on the stability and reversibility of Sn‐based negative electrodes for NIBs.