Finnish team improves low-cost long-life Li-ion cells

University of Eastern Finland researchers have cuts cell resistance in an alternative Li-ion chemistry that avoids expensive cobalt and other rare materials.

Finnish team improves low-cost long-life Li-ion cells

It is working with an anode-cathode pair of lithium titanate and lithium iron phosphate.

“The raw materials for these components are readily available; and they are safe to use, and easy to dispose of or recycle. And most importantly, batteries manufactured using these materials have significantly longer cycle and calendar lifetimes compared to the current battery technology,” said the University, “However, the main problem of these new materials is their low electric conductivity.”

Using high surface area nano-crystalline materials or doping can improve conductivity.

“We have succeeded in doing both for lithium titanate in a simple one-step gas-phase process,” said researcher Tommi Karhunen of the UEF fine particle and aerosol technology lab.

The material of interest is Li4Ti5O12 with ‘defect spinel’ crystal structure, according to the team’s paper (Effect of doping and crystallite size on the electrochemical performance of Li4Ti5O12) in the Journal of Alloys and Compounds.

A process called flame-spray pyrolysis can make it quickly, but resulting crystals cool to quickly and are too small and insufficiently uniform for electrode use.

By using a flow tube furnace to slow cooling, both size and uniformity were improved resulting in “markedly improved” electrochemical performance, said the team.

Introducing silver during flame-spraying adding silver nano-particles to the surface of the Li4Ti5O12 particles, further improve the electrochemical performance at high currents.

Specific capacities increased by up to 6% with the furnace and 19% with the furnace and silver.

“The electrochemical performance of Li-ion batteries made out of the material is very promising.  The most important applications lie in batteries featuring, for example, fast charging required for electric buses, or high power needed for hybrid and electric vehicles,” said Lab director Professor Jorma Jokiniemi.

Kokkola University Consortium Chydenius collaborated in the research.

 


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