SINGAPORE - Researchers in Singapore have re-designed lithium batteries to improve their safe use in electronic products such as personal mobility devices, drones, blood pressure monitors and smart trackers such as the Fitbit.
This promising breakthrough was accomplished by Professor Jackie Y. Ying, Dr Ayman AbdelHamid and Mr Jian Liang Cheong of Agency for Science, Technology and Research's (A*Star) NanoBio Lab (NBL).
Their design of a quasi-solid electrolyte for lithium batteries turns them into a safe and efficient power solution across a wide range of electronic and energy storage applications.
Up till now, the use of liquid organic electrolytes in lithium batteries posed a safety hazard due to leaking and 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, flexible but have limited ionic conductivity at room temperature and are not stiff enough to hold up during battery use."
On the contrary, the quasi-solid electrolytes that the team has designed comprise both liquid and solid components and have "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 a 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 actually baked using an instant mix like Betty Crocker.
"First, we mix the ingredients (metal precursors and sugar) with water, and then place(the mix) in a preset furnace. The furnace has two preset 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) are 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 will likely be more than two times thinner, and which 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.
