(ORDO NEWS) — Scientists at Japan’s Tokyo Metropolitan University have developed a saline solution that reduces resistance between key components inside batteries. The discovery resulted in a battery prototype that is much more stable than its predecessors.
Lithium metal batteries are seen as an extremely exciting prospect in the field of energy storage, as pure lithium metal provides an incredibly high energy density.
Thus, using it instead of graphite and copper, which make up one of the electrodes in modern batteries, can lead to significant performance improvements, allowing, for example, smartphones to work for several days, and electric cars to go much further without recharging.
However, these batteries have been limited by stability issues so far, and one way scientists are working to overcome them is by replacing liquid components with solid ones.
In a design known as solid-state batteries, the lithium ions that carry the battery’s charge travel through a solid electrolyte rather than a liquid one.
But this design also has its drawbacks, including instability at the boundary between the solid electrolyte and battery electrodes.
Experiments with alternative materials and other design changes have recently led to some promising advances, with scientists demonstrating self-assembling protective layers and oily paste as potential solutions.
The team at Tokyo Metropolitan University approached this problem differently by creating a “quasi-solid-state” electrode for use in a solid-state lithium metal battery.
How it works
Funny illustration from scientists explaining the mechanics of the new system
The researchers have been working with a promising potential solid electrolyte called LLZO, which is known to interact relatively well with lithium metal anodes but cause high resistance when paired with conventional cathodes.
The idea was to improve the contact and reduce the resistance between the solid ceramic electrolyte and the cathode by adding a dose of room temperature ionic liquid.
Doping the lithium-cobalt oxide cathode with an ionic liquid filled the tiny voids at the interface between it and the solid electrolyte, which greatly reduced any resistance and promoted ion transport, since the ionic liquid also has ionic conductivity.
In addition, unlike liquid electrolytes used in modern batteries, ionic conductive liquid is non-volatile and generally non-flammable.
The battery prototype with this new quasi-solid state cathode showed impressive stability, retaining 80% of its capacity over 100 charge and discharge cycles at high temperatures up to 60°C.
However, the team still has more work to do to turn the technology into a commercial product, such as adjusting the composition of the ionic liquid to prevent degradation, but scientists see the breakthrough as the basis for new directions in the search for solid-state lithium metal batteries.
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