Solid-state lithium battery targets IoT

April 28, 2016 // By Peter Clarke
Bluetooth beacon
Ilika plc (Southampton, England) has launched the Stereax M250 solid-state battery, which it claims will enable smaller, higher energy density batteries for Internet of Things (IoT) applications.

Ilika – a specialist rapid materials testing company – has adopted a licensing business model for the technology and is now licensing partners for IoT sensors for the smart building, medical, automotive and transport sectors. The advantages that Ilika claims for the Stereax M250 technology over conventional lithium-ion batteries include: smaller footprint, faster charging, longer life span, low leakage current and reduced flammability.

Ilika does not reveal a lot about the materials used in Sterax M250. On its website it says the batteries use similar cathodes to conventional lithium-ion batteries. However, Ilika says it uses different materials for the electrolyte and anode, which are typically lithium based compounds. Ilika states that the anode used in its battery is silicon.

Ilika makes the point that although lithium is included in its battery technology it is not "free" during storage or cycling, in contrast to conventional lithium-ion batteries. Ilika's lithium is alloyed in the cathode or anode and therefore reduces encapsulation requirements. The combination of material and the synthesis method enable a 40 percent energy density improvement per footprint and an increased operating temperature range.

It produces benefits of 6x faster charging, doubled energy density for the same volume, increased life – up to ten years compared to two years and leakage currents of the order of nanoamps, the company claims The output voltage is 3.5 V.

A 10mm by 10mm battery would have a nominal capacity of 250mAh and when charged at 4.0 V would reach 90% of full charge within 10 minutes. The technology is able to sustain more than 5,000 charge-discharge cycles and delivers a peak current of 5 mA.

This makes the Stereax M250 suitable for autonomous sensors for the Internet of Things. The low self-discharge allows it to be trickle charged from an energy harvesting source. Its high peak current allows electronics to be powered for burst transmission of data.

Thus a sensor, wireless transmitter, energy harvester, and M250 battery could be integrated into "fit and forget" autonomous wireless sensor nodes for applications in smart homes, automotive, logistics and medical devices.