New Electrode Material Potentially Doubles Smartphone Battery Capacity

A material discovered by ETH Zurich researchers led by Dr. Semih Afyon and Reinhard Nesper may have the potential to double battery capacity.

Researchers are using the Vanadate-borate glass as a cathode material.

It is made of vanadium oxide (V2O5) and lithium-borate (LiBO2) precursors, and was coated with reduced graphite oxide (RGO) to enhance the electrode properties of the material.

They used a vanadium-based compound because vanadium is a transition metal with various oxidation states, which can be exploited to reach higher capacities.

To produce the cathode material, Afyon and his colleagues blended powdered vanadium pentoxide with borate compounds.

"Borate is a glass former; that's why the borate compounds were used, and the resulting glass compound is a new kind of material, neither V2O5 nor LiBO2 at the end," the researcher said.

The scientists melted the powder at 900-degrees Celsius and cooled the melt as quickly as possible to form glass.

The resulting paper-thin sheets were then crushed into a powder before use, as this increases their surface area and creates pore space.

"One major advantage of vanadate-borate glass is that it is simple and inexpensive to manufacture," said Afyon. This is expected to increase the chance of finding an industrial application.

To produce an efficient electrode, the researcher coated the vanadate-borate powder with reduced graphite oxide (RGO).

This increases conductivity while at the same time protecting the electrode particles.

One battery with an RGO-coated vanadate-borate glass electrode exhibited an energy density of around 1000 watt-hours per kilogram.

It achieved a discharge capacity that far exceeded 300mAh/g. Initially, this figure even reached 400mAh/g, but dropped over the course of the charge/discharge cycles.

"This would be enough energy to power a mobile phone between 1.5 and two times longer than today's lithium-ion batteries," Afyon said.

The research was published in the journal Scientific Reports.