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Low-Temperature Performance of a Ferroelectric Glass Electrolyte Rechargeable Cell

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journal contribution
posted on 2019-05-15, 00:00 authored by M. H. Braga, A. J. Murchison, J. E. Oliveira, J. B. Goodenough
An electrochemical cell that powers all-electric road vehicles will likely have an alkali-metal anode and the ability to operate down to −20 °C. The traditional all-solid-state batteries can only perform well at temperatures above room temperature. We have shown elsewhere that an alkali-metal negative electrode can be plated dendrite-free from a ferroelectric amorphous-oxide (glass) Li+ or Na+ electrolyte having a room-temperature Li+ or Na+ conductivity σi ≈ 2.5 × 10–2 S cm–1 which is similar to that of a liquid electrolyte. Here, it is demonstrated that the ionic conductivity of the electrolyte is σi ≈ 10–2 S cm–1 at −20 °C after optimization, and the dielectric constant is ε′r ≈ 6 × 105 at −35 °C. Moreover, it is shown that the remanent polarization of the ferroelectric-electrolyte (polarization at zero potential) adds to the capacity of the cell. The electrochemical cycling performances between −35 and 25 °C of the Li+-glass electrolyte in gold and lithium symmetric cells and in full cells are presented. Furthermore, it is shown that a coin-cell with the ferroelectric Li-glass electrolyte at −35 °C with output current of 56 μA cm–2 can light a red LED at 1.5 V. Finally, it is concluded that the Li+-glass electrolyte performs very well in symmetric cells and performs reasonably well down to −20 °C in asymmetric cells that also rely on the performance of the cathode and on the electrolyte/cathode interface.