nz9b00459_si_001.pdf (697.33 kB)
Dissolution of Lithium Metal in Poly(ethylene oxide)
journal contribution
posted on 2019-03-20, 00:00 authored by Michael
D. Galluzzo, David M. Halat, Whitney S. Loo, Scott A. Mullin, Jeffrey A. Reimer, Nitash P. BalsaraWe demonstrate that
lithium metal is sparingly soluble in poly(ethylene
oxide) (PEO). 7Li NMR shows that when a PEO sample is placed
in contact with lithium metal at elevated temperatures, a lithium
species dissolves and diffuses into the bulk polymer. A lithium/PEO/lithium
electrochemical cell, containing no lithium salts, shows increasing
conductivity over time when annealed at 120 °C. Chronoamperometry
shows that the annealed cell obeys Ohm’s law, implying that
conduction occurs without the development of concentration gradients.
To explain the results, it is proposed that atomic lithium dissolves
into PEO, where it exists as a lithium cation and free electron. The
dissolution of lithium also affects the phase behavior of block copolymer
electrolytes. These observations explain the strong adhesion between
lithium metal and PEO and have important implications for lithium
metal battery systems that contain PEO-based electrolytes.