By Polaris Battery Labs
Solid-state electrolytes (SSE) have been on the technology roadmap for rechargeable Lithium batteries for several decades now.
The perceived benefits of these electrolytes for improving safety and for enabling the use of high energy-density Lithium metal anodes have motivated many researchers to develop novel solid-state Lithium ion conductors. Figure 1 compares the basic construction of a Lithium-ion battery (LIB) with a Lithium-metal battery (LMB) that contains an SSE.
In an LIB, ion transport between anode (Carbon -graphite) and cathode (Lithium Metal Oxide), is facilitated by solvated Lithium ions from a salt dissolved in a non-aqueous organic solvent, which forms a liquid electrolyte (LE). To prevent the anode and cathode from shorting in the tightly wound (or stacked) implementation of the cell, a microporous, electrolyteabsorbing separator-membrane (Sep) is used. In an LIB containing a gel-electrolyte, the liquid electrolyte forms a gel with a polymer.
Cells containing gel-electrolytes may use separators for improved performance. While the liquid-electrolyte-separator (LE-Sep) configuration is primarily used in cells packaged in metal cans, the gel-electrolyte configuration is preferred for pouch cells, as the gel enables the desired stack pressure in a soft-package. An SSE replaces the LE-Sep (or the gel-electrolyte) with a single solid-state lithium-ion conducting layer, that performs both the electrolyte and separator functions.
By eliminating the flammable non-aqueous electrolyte solvent, cell safety is significantly enhanced. Furthermore, solid electrolytes enable use of higher energy density Lithium metal electrodes, thereby paving a path to higher energy density energy storage, compared to state-of-the -art Lithium-ion.
