An ion is an atom that carries an electrical charge. Metal-based batteries, such as sodium and lithium, move their ions to their positive electrodes when discharging. If these are secondary batteries though, an external electric supply can move the ions back to their negative electrodes during recharging. Scientists at Rice University have discovered a new method for sourcing these lithium ions.
Why a Different Method for Sourcing Lithium Ions?
Battery manufacturers traditionally use lithium taken from the earth, and brine. However, there could be a shortage looming, as these sources dry up. The energy-storage, automotive, and transport sectors are increasingly interested in finding alternative ways to obtain lithium.
Scientists at Rice University have discovered a creative way to achieve this goal. Lithium-ion batteries use electrolytes that only allow lithium-ions to pass through. Have we stumbled over a new way to selectively extract lithium-ions, they wondered?
The Rice team knew that lithium is soluble, and naturally present in many liquids, including water. What they needed was a suitable filter, and then an amazing new idea came to them. Here’s their new method for sourcing lithium ions, expressed as simply as we can:
- Solid state lithium electrolytes shuttle lithium ions through a structured crystalline lattice.
- This is a repeating three-dimensional pattern of atoms, or groups of atoms in a crystal.
- Only lithium-ion ions can pass through this lattice. Even water is unable to find a way through.
Where to From Here With This Amazing Idea?
This new method for sourcing lithium ions was effective under laboratory conditions. The researchers only needed a very small amount of energy to move the ions across the lattice membrane.
Even when the scientists used high concentrations of competing ions, only the lithium was able to get past.
“The lattice acts as a molecular sieve, allowing only lithium ions to pass,” a team member comments. “This combination of highly precise size and charge exclusion, is what makes the solid state electrolyte membrane so unique.”
More Information
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