Salt baths greatly boost charge efficiency for lithium batteries

The Room Temperature Ionic Liquid (RTIL) electrolytes developed by CSIRO, RMIT and Queensland University of Technology may hold the key to solving electric car “battery range anxiety”.

The next generation of rechargeable lithium batteries set to disrupt the electric vehicle industry may soon be here, thanks to the humble salt bath.

CSIRO scientists, in collaboration with RMIT University and QUT, have demonstrated that pre-treating a battery’s lithium metal electrodes with an electrolyte salt solution extends the battery life and increases performance and safety.

The research was published in Nature Communications.

The simple method is set to accelerate the development of next-gen energy storage solutions and overcome the issue of ‘battery range anxiety’ that is currently a barrier in the electric car industry.

The technology has the potential to improve electric vehicle drive range and battery charge to a point where electric vehicles will soon be competitive with traditional petrol vehicles.

CSIRO battery researcher Dr Adam Best said the pre-treated lithium metal electrodes could potentially outperform other batteries currently on the market.

“Our research has shown by pre-treating lithium metal electrodes, we can create batteries with charge efficiency that greatly exceeds standard lithium batteries,” Dr Best said.

The pre-treatment process involves the immersion of lithium metal electrodes in an electrolyte bath containing a mixture of ionic liquids and lithium salts, prior to a battery being assembled.

Ionic liquids or room temperature molten salts, are a unique class of material that are clear, colourless, odourless solutions and are non-flammable.

When used in batteries these materials can prevent the risk of fire and explosion, a known rechargeable battery issue.

The salt bath pre-treatment adds a protective film onto the surface of the electrode that helps stabilise the battery when in operation.

“The pre-treatment reduces the breakdown of electrolytes during operation, which is what determines the battery’s increased performance and lifetime,” Dr Best said.

Batteries that have undergone the process can also spend up to one year on the shelf without loss of performance.

QUT researcher Assoc. Prof. Anthony O’Mullane said the method can be easily adopted by manufacturers.

“The pre-treatment process is readily transferrable to existing manufacturing processes,” Assoc. Prof. O’Mullane said.

The electrolyte salt solutions, to which CSIRO holds patents, come in a range of chemical compositions.

The research formed part of Dr Andrew Basile’s doctoral thesis with RMIT University, working closely with CSIRO scientist Dr Anand Bhatt to investigate battery processes occurring at lithium metal.

The team of scientists is currently developing batteries based on this technology, and are looking for partners to help bring these materials and devices to market.

Learn more: Salt baths boost next gen batteries for electric cars