Researchers at the University of Texas at Austin have devised a new strategy for an all-solid-state sodium or lithium EV battery cell.
In “Alternative Strategy for a Safe Rechargeable Battery,” published in Energy & Environmental Science, noted lithium-ion battery pioneer Professor John Goodenough and his colleagues explain that the cells use a solid glass electrolyte. The glass has a surface that is wet by metallic lithium or sodium, which allows reversible plating/stripping of an alkali-metal anode without dendrites. It also contains electric dipoles that give it a large dielectric constant.
To fabricate test cells, the researchers introduced Na+ and Li+ glass electrolytes into either a fiberglass sheet or a thin sheet of recycled paper from a slurry of the glass particle sin ethanol. They heated the membranes to outgas the ethanol and reform the solid glass electrolyte without grain boundaries, then pressed these against an anode of Li or Na foil.
The electrolyte membrane was 0.06 mm thick. The cathode consisted of a redox center embedded in a mix of electrolyte and carbon contacting a Cu current collector. This cathode composite was pressed against the electrolyte membrane in a coin-cell configuration. The sealed cell was then aged.
“The ability to plate/strip reversibly an alkali-metal anode from a solid electrolyte invites a complete rethink of rechargeable-battery strategies,” write the researchers. “With the Li-glass and Na-glass electrolytes, we have demonstrated one possible new strategy in which the cathode consists of plating the anode alkali-metal on a copper-carbon cathode current collector at a voltage greater than 3.0 V.”
Source: Green Car Congress