TDK develops new material for solid-state batteries: why it's a major breakthrough

Credit: TDK

Japanese society TDKamong the world leaders in the production of small batteries, has developed a new material which promises a turning point in the field of solid state batteriespotentially capable – so declares the Tokyo-based company – of leading to a new generation of batteries with an energy density of ben 1000 watt hours per liter, 100 times larger than current solid-state batteries produced by TDK. The importance of this number is that it makes possible batteries capable of store more energy in a smaller space. The company does not provide details on the material in question: at the moment we only know that it is solid, “oxide-based” and that it will be used in ceramic batteries with lithium alloy anodes. According to TDK, this technology will allow the creation of rechargeable batteries that are smaller, longer lasting and safer than traditional lithium batteries, to be used for wearable devices (wireless earphones, smartwatches, hearing aids etc.) and to replace coin batteries (which are not rechargeable) in accordance with EU regulations, with a significant environmental advantage. Second Noboru Saito, CEO of TDK, “the newly developed solid-state battery material can make a significant contribution to society's energy transformation”; he then adds that «we will continue development aimed at commercialization as soon as possible».

The news was welcomed as a potential revolutionary turning point precisely because solid-state batteries promise a big step forward in the energy field. Conceptually these are lithium ion batteries like traditional ones, with the crucial difference that theelectrolyte (i.e. the material that allows the movement of ions during the charging and discharging phases) is not liquid but solid. This has several advantages: one higher energy density (i.e. the amount of energy that can be stored per unit of volume or mass), a faster charging process (about 5 times compared to traditional batteries), one longer duration (due to greater electrochemical stability) and one greater security. In particular, solid-state batteries are safer because liquid electrolytes are generally flammable and can explode: even a small rupture in the battery casing can therefore be very risky.

This is why there is so much attention on solid-state batteries: it avoids all those risks for devices that must be in direct contact with our body, and their high energy density allows the batteries to be much smaller and lighter and at the same time to be recharged much more rarely and quickly compared to liquid electrolyte batteries.

It must be said that at the moment solid-state battery technology is still under development and has many obstacles to overcome. For now, these batteries are produced in small sizes because production processes are very complex and expensive. Then there are engineering issues: for example, in the specific case of TDK the ceramic material used by the company would make larger batteries for smartphones or electric vehicles very fragile. At the moment, having large solid-state batteries is a technological and engineering challenge that we still have to overcome, but the efforts are enormous because this could lead to a real revolution in the field of electric mobility, where autonomy and battery life are essential to minimize environmental impact. Automotive companies such as Toyota, Nissan and Honda are focusing heavily on solid-state batteries with electrolyte-based sulfur, best suited for batteries large enough to power cars. At the moment, however, there are still several problems and it is impossible to predict when these technologies could enter the mass production phase.

TDK is working to employ the newly developed material in solid-state batteries capable of mass production, while working in parallel to increase the batteries' capacity and operating temperature range.