Improved ionic conductivity and battery function in a lithium iodide solid electrolyte via particle size modification. (20th August 2021)

• Record Type: Journal Article
• Authors: Dunkin, Mikaela R.; King, Steven T.; Takeuchi, Kenneth J.; Takeuchi, Esther S.; Wang, Lei; Marschilok, Amy C.
• Is Part Of: Electrochimica acta. Volume 388(2021)
• Publication Date: 2021-08-20
• Subjects: Lithium iodide -- Particle size -- Ionic conductivity -- Solid-state battery -- Self-healing; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.138569
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Solid electrolytes (SEs) are a promising, safe alternative to liquid electrolytes in high energy density batteries, but low conductivity issues remain a challenge. Herein, a lithium iodide based solid electrolyte (SE) was improved by reducing particle size via several processing methods, i.e. grinding and/or sonication. Particle size was reduced from 5 ± 1 µm to 2.0 ± 0.2 µm, resulting in an order of magnitude increase in ionic conductivity, from 7.7×10 −8 to 6.1×10 −7 S cm-1, at room temperature. Improved conductivity is attributed to an increased number of grain boundaries and defects, enabling ion transport and better mixing with the electrolyte additive, 1:2 lithium iodide: 3-hydroxypropionitrile (LiI(HPN)2 ). 3D confocal Raman spectroscopy in conjunction with non-negative matrix factorization (NMF) analysis determined the degree of HPN aggregation was lessened in the sample with smallest particle size. This LiI SE was utilized in a self-forming Li/I2 battery, where reduced particle size (improved conductivity) led to significantly reduced overpotential, allowing the coulombic efficiency to reach 100% in the first cycle. Furthermore, a more stable electrochemical response was achieved when cycled at higher current densities.