AsianScientist (Dec. 3, 2018) – A research team at Osaka University, Japan, has drawn inspiration from living cells to create a material that could improve the safety of rechargeable batteries while lowering their manufacturing costs. The study results are published in Chemical Science.
Rechargeable lithium-ion batteries are widely used in laptops, cell phones and electric cars. Unfortunately, these batteries are expensive and have even been known to catch fire on occasion. New materials that do not use lithium could reduce the cost and improve the safety of these batteries, as well as accelerate the adoption of energy-efficient electric cars.
Sodium and potassium ions, which are inexpensive and abundant, could replace lithium in batteries. However, because these ions are much larger than lithium ions, they move sluggishly through most materials.
To solve this problem, researchers led by Professor Takumi Konno of Osaka University developed an ionic crystal using rhodium, zinc and oxygen atoms that behaves like a biological ion channel, allowing the rapid movement of potassium ions within its lattice structure.
Living systems regulate the passage of ions by considering not just the ions themselves, but also the surrounding water molecules, called the hydration layer, that are attracted to the ion’s positive charge. The smaller the ion, the larger and more tightly bound its associated hydration layer will be.
The researchers observed that their ionic crystal could impede ions based on the size of their associated hydration layers. Hence, the larger potassium ions, which have smaller hydration layers, were free to move within the crystal. In contrast, the smaller lithium ions were surrounded by large hydration shells and therefore could not migrate quickly inside the lattice. The researchers claim that their ionic crystal has the largest hydrated potassium ion mobility seen to date.
“Remarkably, the crystal exhibited a particularly high ion conductivity due to the fast migration of hydrated potassium ions in the crystal lattice” said lead author Dr. Nobuto Yoshinari of Osaka University. “Such superionic conductivity of hydrated potassium ions in the solid state is unprecedented, and may lead to both safer and cheaper rechargeable batteries.”
The article can be found at: Yoshinari et al. (2018) Mobility of Hydrated Alkali Metal Ions in Metallosupramolecular Ionic Crystals.
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Source: Osaka University; Photo: Shutterstock.
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