A*Star team finds way to make lithium batteries safer

(From left) Dr Ayman AbdelHamid, Professor Jackie Y. Ying and Mr Jian Liang Cheong, the A*Star NanoBio Lab researchers who have designed a quasi-solid electrolyte for lithium batteries. Prof Ying is holding the electrolyte, made using a process that
(From left) Dr Ayman AbdelHamid, Professor Jackie Y. Ying and Mr Jian Liang Cheong, the A*Star NanoBio Lab researchers who have designed a quasi-solid electrolyte for lithium batteries. Prof Ying is holding the electrolyte, made using a process that she likens to baking cupcakes. PHOTO: NANOBIO LAB

Their quasi-solid electrolyte poses no risk of leaking, yet keeps battery performance high

Researchers in Singapore have found a way to make lithium batteries safer for use in electronic products such as personal mobility devices, drones, blood pressure monitors and smart trackers.

The promising breakthrough was accomplished by Professor Jackie Y. Ying, Dr Ayman AbdelHamid and Mr Jian Liang Cheong of the Agency for Science, Technology and Research's (A*Star) NanoBio Lab (NBL).

Their design of a quasi-solid electrolyte for lithium batteries turns the batteries into a safe and efficient power solution across a wide range of electronic and energy storage applications.

The use of liquid organic electrolytes in lithium batteries poses a safety hazard owing to the risk of leaks and their high flammability.

Solid-state electrolytes, on the other hand, while safer to use in lithium batteries, lead to major conductivity bottlenecks and low performance.

Prof Ying, who heads the NBL research team, explained: "Solid-state electrolytes are classified into two main classes.

"First, inorganic materials that have relatively high ionic conductivity but are difficult to process, (are) brittle and cannot have good contact with electrodes because of poor solid-solid contact, and second, polymers that are processable and flexible but have limited ionic conductivity at room temperature and are not stiff enough to hold up during battery use."

The quasi-solid electrolyte that the team has designed comprises both liquid and solid components and has "emerged as a practical compromise to obtain safer batteries while maintaining good performance", noted Prof Ying.

However, the team grappled with the solid component's high resistance, which was limiting battery performance.

"To overcome this, we have re-engineered the microstructure of the solid component. Our solution eliminates electrolyte leakage, and is thermally and mechanically stable," said Prof Ying.

In designing the hybrid quasi-solid electrolyte, which comprises a liquid-infused porous sheet-based membrane, the team developed a new method of fabricating the inorganic sheets used to construct the 3D framework of the membrane.

 
 
 

They named this one-step process "the cupcake method".

Prof Ying likened the process to how cupcakes are baked using an instant mix.

"First, we mix the ingredients (metal precursors and sugar) with water, and then place (the mix) in a pre-set furnace. The furnace has two pre-set temperatures - at the first temperature, a solid is formed, which is then left in the furnace to remove the organic components and leave behind the sheets.

"This remaining material (sheets) is what we use to form the scaffold for our quasi-solid electrolyte," said Prof Ying.

The electrolyte's non-rigid structure allows it to maintain good contact with electrodes and prevents it from cracking during handling and battery assembly.

The end result is safer batteries with better performance.

The NBL team is currently developing a second-generation hybrid quasi-solid electrolyte with even safer components, which is likely to be more than two times thinner, and will further enhance the battery's energy density.

Prof Ying said it would take one to two years for this technical breakthrough to find commercial use.

A version of this article appeared in the print edition of The Straits Times on March 28, 2020, with the headline 'A*Star team finds way to make lithium batteries safer'. Print Edition | Subscribe