Solid state batteries: The next evolution in Li-ion technology?

By IM Staff
Published: Thursday, 23 February 2017

Lithium-ion batteries have been plugged as the enablers of countless next generation electronic devices, but there remain kinks in the technology that engineers are struggling to iron out. Rose Pengelly, IM Correspondent, spoke to high-tech materials developer Ilika about how solid state designs may provide some of the answers battery users are looking for.

Electronics is a fast-paced industry. Barely a month passes without the launch of a brand new, high-powered smart device claiming to revolutionise the way we live, work or drive and most of these products are made possible by batteries.

Amid the seemingly relentless march of technological progress, it is perhaps easy to overlook the fact that engineering the batteries that make many of these advances possible is a difficult process in which the odds are on failure.

Incidents of lithium-ion (Li-ion) batteries in phones, cars and even aeroplanes catching fire have served as sobering reminders that this said to be game-changing chemistry is not yet perfect. As a consequence, rafts of researchers around the world are working feverishly to try and design better batteries.

One company doing just that is Ilika Plc, a UK AIM-listed new materials specialist, which is developing Li-ion solid state batteries (SSB) that it believes can resolve many of the issues associated with incumbent Li-ion technology and create openings for batteries to be used in a variety of new applications.

Instead of using the liquid or polymer electrolyte found in conventional Li-ion batteries, SSBs use a solid ion conductor – a ceramic one, in Ilika’s case – making the battery less flammable.

Estimates for the size of the SSB market vary. Ilika quotes figures from France-based industry consultants Avicenne, which forecast that the sector’s value will grow from $8bn in 2013 to around $32bn by next year. 

A more recent forecast by research firm Markets and Markets predicts the industry will be worth just $1.1bn by 2020, while emerging technology tracker IDTechEx estimates a market size of $7bn by 2027. 

This suggests either wild over-optimism on the part of Avicenne, which could not be reached to discuss its projections, or that there is some discrepancy between what different forecasters include within their definition of SSBs. 

According to IDTechEx, Li-ion batteries celebrated their 25th commercial anniversary last year, but the relative lack of significant innovation in their design over the last two and a half decades has brought to light limitations in terms of their safety, performance and cost.

Lithium-iodine SSBs were first commercialised in the 1970s to power pacemakers, but it is only fairly recently with the introduction of new sulphide-based materials that SSBs have been made rechargeable and considered as potential competitors to their more prevalent liquid electrolyte counterparts.

Graeme Purdy, Ilika’s CEO, says that SSBs are not in direct
competition with conventional Li-ion technology but have their own specific target markets. (Source: Ilika)

Ilika’s SSBs

Graeme Purdy, Ilika’s CEO, says that his company was prompted to develop an alternative to "traditional" lithium batteries when Toyota Motor Corp. began putting out feelers for more reliable technology to power its hybrid-electric vehicles (EVs).

Toyota launched its best-selling Toyota Prius electric-gasoline hybrid in 1997, powered by nickel-metal-hydride (NiMH) batteries. Since then, it has experimented with various lithium battery chemistries, including liquid electrolyte Li-ion technology, and is now using Ilika’s high throughput physical vapour deposition (HT-PVD) technology to develop batteries for its next phase of plug-in hybrid EVs.

"We were first approached by Toyota in 2008, which has a vision to replace the Li-ion batteries in its hybrid vehicles with SSBs because of their improved safety profile," Purdy told IM

"During the course of that work, we realised that SSB technology – in which flammable liquid electrolyte is replaced with a solid ion-conductor – could be used to produce batteries that can power autonomous sensing devices for the Internet of Things in many areas such as medical, industrial, agriculture, sensors for smart cars and homes."

Liquid state batteries contain a cathode and an anode prepared from powders mixed to form an ink, deposited as slurry, which is first dried then calendared to make films several 10s, even 100s of microns thick. By contrast, Ilika’s separator films, deposited by PVD, are just a few microns thick.

As well as making it less prone to igniting, this battery design imparts other advantages, including a smaller footprint, faster charging, longer life span and low leakage.

Although Toyota is using Ilika’s technology to design alternative Li-ion batteries for its cars, Ilika insists that its trademarked Stereax SSBs, which it makes itself and are the company’s first product available for commercial licensing, do not compete directly with traditional Li-ion technologies. 

"Stereax batteries are useful for miniature applications in medical devices and the semiconductor industry as well as in high temperature environments," Purdy explains. 

These batteries are made from many of the same materials as conventional Li-ion products, but because Ilika currently only produces them in small quantities, their selling price is higher than the mass produced Li-ion batteries.

Diagram of Ilika’s SSB. These graphite-free batteries allow for miniaturisation
and higher performance. (Source: Ilika)

Raw materials

Like other Li-ion batteries, Ilika’s SSBs rely on raw materials derived from natural resources. Purdy says that the company sources the lithium for its batteries in pellet form from speciality metal suppliers, but declines to divulge any further details about its procurement.

Average spot prices for lithium have increased threefold since 2014, but Purdy is not worried, for now, about rising costs or availability of this key raw material. 

"We are aware about the risks associated with lithium being sourced from a small number of countries, however our SSBs use so little lithium – it represents less than 1% of the battery, that’s under a milligram – that the cost does not concern us at the moment," he told IM. "Clearly, when the shipped volume of our Stereax SSBs grows, fluctuations in materials costs may have a larger effect."

Unlike conventional Li-ion batteries, Ilika’s SSBs do not contain graphite. "This is used in conventional batteries to increase electrical conductivity in electrodes. The Stereax SSB has thin films that do not require additional help for the conduction of charge," Purdy explains.

Potential for growth

Demand growth for Li-ion batteries is being driven by the EV and energy storage markets. EV production growth and the sharp rise in Li-ion battery manufacturing was one of the most eye-catching industrial trends of 2016 and most industry observers agree that battery consumption as a whole is set for strong growth as consumer and industry demand for electronic devices expands.

Because solid state lithium batteries are considered likely to be safer than current liquid state chemistries and can potentially offer better performance, the technology could be used in a number of new applications on top of the major existing Li-ion markets.

Ilika is currently targeting two specific sectors as priorities: millimeter-sized batteries to power implantable medical devices and industrial applications related to factory automation and so-called "Industry 4.0" – a trend towards automation and data exchange in manufacturing technologies. Purdy says that the company is in commercial discussions with potential licensees in these sectors.

But while new models of the same kinds of battery powered devices – such as smart phones and tablet computers – roll off production lines with almost alarming frequency, meaningful advancements in actual Li-ion chemistries have felt like a long-time coming, particularly for investors wooed by bullish market penetration scenarios pedalled by everyone from mining companies to industrial conglomerates over the last decade.

According to London-based stockbroker Beaufort Securities, Ilika’s ambitious aims are focused on the right areas – namely miniaturisation, capacity in a small footprint and increased performance – but the company has not delivered results fast enough for some.

"Progress is being made, although significant underperformance during the past year tells us that investors are growing weary of Ilika’s forever jam-tomorrow stories," the brokerage said in a recent note on Ilika.

It added that highly protected technologies "should be capable of delivering the knock-out blow" at some point. 

However, this field is congested and competitive. SSBs, including batteries with non Li-ion formulas, are being researched by well-funded companies and institutions in Switzerland, the US, Korea and Japan, among others. 

The challenge for Ilika, as with all SSB developers, is to nail down licensing deals with industrial majors. Until this happens, SSBs are just another concept floating in a crowded sea of research, trying to net the next big fish in battery technology.