New designs for solid-state electrolytes may soon revolutionize the battery industry

Researchers led by Professor KANG Kisuk of the Center for Nanoparticle Research within the Institute for Basic Science (IBS), have announced a major breakthrough in the field of next-generation solid-state batteries. It is believed that their new findings will enable the creation of batteries based on a novel chloride-based solid electrolyte that exhibits exceptional ionic conductivity.

A pressing concern with current commercial batteries their reliance on liquid electrolytes, which leads to flammability and explosion risks. Therefore, the development of non-combustible solid electrolytes is of paramount importance for advancing solid-state battery technology. As the world gears up to regulate internal combustion engine vehicles and expand the use of electric vehicles in the ongoing global shift toward sustainable transportation, research into the core components of secondary batteries, particularly solid-state batteries, has gained significant momentum.

To make solid-state batteries practical for everyday use, it is crucial to develop materials with high ionic conductivity, robust chemical and electrochemical stability, and mechanical flexibility. While previous research successfully led to sulfide and oxide-based solid electrolytes with high ionic conductivity, none of these materials fully met all these essential requirements.

In the past, scientists have also explored chloride-based solid electrolytes, known for their superior ionic conductivity, mechanical flexibility, and stability at high voltages. These properties led some to speculate that chloride-based batteries are the most likely candidates for solid-state batteries. However, these hopes quickly died out, as the chloride batteries were considered impractical due to their heavy reliance on expensive rare earth metals, including yttrium, scandium, and lanthanide elements, as secondary components.

To address these concerns, the IBS research team looked at the distribution of metal ions in chloride electrolytes. They believed the reason trigonal chloride electrolytes can achieve low ionic conductivity is based on the variation of metal ion arrangements within the structure.

They first tested this theory on lithium yttrium chloride, a common lithium metal chloride compound. When the metal ions were positioned near the pathway of lithium ions, electrostatic forces caused obstruction in their movement. Conversely, if the metal ion occupancy was too low, the path for lithium ions became too narrow, impeding their mobility.

Building on these insights, the research team introduced strategies to design electrolytes in a way that mitigates these conflicting factors, ultimately leading to the successful development of a solid electrolyte with high ionic conductivity. The group went further to successfully demonstrate this strategy by creating a lithium-metal-chloride solid-state battery based on zirconium, which is far cheaper than the variants that employ rare earth metals. This was the first instance where the significance of the metal ions arrangement on a material's ionic conductivity was demonstrated.

This research brings to light the often-overlooked role of metal ion distribution in the ionic conductivity of chloride-based solid electrolytes. It is expected that the IBS Center's research will pave the way for the development of various chloride-based solid electrolytes and further drive the commercialization of solid-state batteries, promising improved affordability and safety in energy storage.

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Muscle cramp? Drink electrolytes, not water

 If you reach for water when a muscle cramp strikes, you might want to think again. New research from Edith Cowan University (ECU) has revealed drinking electrolytes instead of pure water can help prevent muscle cramps.

The study, published in the Journal of the International Society of Sports Nutrition, found that people who drank electrolyte enhanced water during and after exercise were less susceptible to muscle cramps than those who drank pure water.

Muscle cramps are a common painful condition affecting many people, including around 39 per cent of marathon runners, 52 per cent of rugby players and 60 per cent of cyclists.

Dilution solution

Lead researcher Professor Ken Nosaka, from ECU's School of Medical and Health Sciences, said the study builds on the evidence that a lack of electrolytes contributes to muscle cramps, not dehydration.

"Many people think dehydration causes muscle cramps and will drink pure water while exercising to prevent cramping," he said.

"We found that people who solely drink plain water before and after exercise could in fact be making them more prone to cramps.

"This is likely because pure water dilutes the electrolyte concentration in our bodies and doesn't replace what is lost during sweating."

When cramp strikes

Professor Nosaka began researching the causes of muscle cramps after regularly suffering from them while playing tennis.

The study involved 10 men who ran on a downhill treadmill in a hot (35ºC) room for 40 to 60 minutes to lose 1.5 to 2 per cent of their body weight through sweat in two conditions.

They drank plain water during and after exercise for one condition and took a water solution containing electrolytes in the other condition.

The participants were given an electrical stimulation on their calves to induce muscle cramp. The lower the frequency of the electrical stimulation required, the more the participant is prone to muscle cramp.

"We found that the electrical frequency required to induce cramp increased when people drank the electrolyte water, but decreased when they consumed plain water," said Professor Nosaka.

"This indicates that muscles become more prone to cramp by drinking plain water, but more immune to muscle cramp by drinking the electrolyte water."

Not all water is equal

Electrolytes are minerals including sodium, potassium, magnesium and chloride. They are essential for muscle health and help the body to absorb water.

Oral rehydration solutions contain electrolytes in specific proportions and can be made with water, salt and sugar. They are commonly found in supermarkets and pharmacies.

Professor Nosaka said electrolytes have many benefits for both athletes and the general population.

"Electrolytes are vital to good health -- they help the body to absorb water more effectively than plain water and replace essential minerals lost through sweat or illness," he said.

"People should consider drinking oral rehydration fluids instead of plain water during moderate to intense exercise, when it's very hot or when you are sick from diarrhoea or vomiting."

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