Low-Temperature Performance of a Ferroelectric Glass Electrolyte Rechargeable Cell

An electrochemical cell that powers all-electric road vehicles will likely have an alkali-metal anode and the ability to operate down to -20 degrees 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 sigma(i) approximate to 2.5 x 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 sigma(i) approximate to 10(-2) S cm(-1) at -20 degrees C after optimization, and the dielectric constant is epsilon'(r) approximate to 6 X 10(5) at -35 degrees 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 degrees 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 degrees C with output current of 56 mu A 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 degrees C in asymmetric cells that also rely on the performance of the cathode and on the electrolyte/cathode interface.