AUTHOR=Rudola Ashish , Wright Christopher J. , Barker Jerry 

TITLE=Explorations Into the Viability of High Voltage Bipolar Na-Ion Cells Using Liquid Electrolytes

JOURNAL=Frontiers in Energy Research

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2022.852630

DOI=10.3389/fenrg.2022.852630

ISSN=2296-598X

ABSTRACT=<p>Bipolar electrodes can be defined as electrodes where cathode and anode active materials exist on either side of a shared current collector substrate. The resultant rechargeable bipolar batteries, using series-connected electrochemical cells within one sealed enclosure, can enable high-voltage systems irrespective of the voltage of the cathode//anode couple used. The sodium-ion battery, being well-suited for the bipolar concept, is now rapidly being commercialized and has higher energy densities than most rechargeable battery technologies. However, bipolar sodium-ion batteries using commercially-feasible liquid electrolytes and manufacturing methodologies, have not been demonstrated at scale yet. Herein, we explore the design methodology needed to enable commercial realization of such bipolar sodium-ion batteries, using liquid electrolytes and different types of cathode//anode couples. We show good cycling stabilities over 200 cycles and potential for voltages beyond 6 V for bipolar Na-ion pouch cells. We also introduce a scalable method to fabricate <italic>n</italic>S<italic>m</italic>P Na-ion/mixed-chemistry bipolar cells (<italic>n</italic> cells in series; <italic>m</italic> cells in parallel) in a single, sealed cell. Our results point to realistic promise for high voltage and sustainable bipolar sodium-ion batteries.</p>