Solid-state electrolytes drive the quest for a safer battery 

April 05, 2017 // By Nick Flaherty
IDtechX market prediction for solid state batteries
This year could mark the first significant switch to new materials in the electrolyte compartment, with both large and small companies trying to bring inorganic and polymer electrolytes to commercial fruition, says Dr Lorenzo Grande, Technology Analyst at market researcher IDTechEx.

He points to polymer-based electrolytes that are already used in Bolloré’s cars in France, and several companies like SEEO, Solvay, and Solidenergy developing organic ionic conductors for wearables, drones and electric vehicles. Solvay in particular is promoting its research and development on gel polymer electrolytes for low-power applications, he says.

Volkswagen, BMW, Toyota, Hyundai, and many other automotive companies are also looking at the technology for safer batteries. Grande highlights Toyota as the car company doing the most work in this field, demonstrating a golf cart in Japan equipped with a small inorganic solid-state battery, with an energy density that is in the 200-400 Wh/L range. Toyota is using a composite electrolyte made of LLZO particles immersed in a LPS matrix.

Solid-state batteries can be made thinner, flexible, and contain more energy per unit weight than conventional Li-ion. In addition, the removal of liquid electrolytes can be an avenue for safer, long-lasting batteries. With a battery market currently dominated by Asian companies, European and US firms are striving to win this arms race that might shift added value away from Japan, China, and South Korea he says.

However, he points out that inorganic solid-state electrolytes are significantly heavier than liquid ones, and interfacial properties are not yet optimised to enable stability to the anode and the cathode. On top of that, solid electrolytes only make sense in terms of performance enhancement if lithium metal is used as anode material.

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