The main problem with solid-state batteries is that we have not yet found the ideal electrolyte. Of course, we have made plenty of progress in this direction – just look at the many scientific papers that have already been published on the topic. But the fact remains that the world of batteries is still not much further down the road than the first generation of lithium solid-state batteries of the type that are used, for example in pacemakers. And which only deliver a very small amount of current.
Our research center (imec) is on a quest to find the best electrolyte material for solid-state batteries. We are currently focusing on composite electrolytes. There are two other types of electrolytes, but they still have quite a few disadvantages. The first of these types, polymer electrolytes, do not have sufficient conductivity, while inorganic electrolytes require a high process temperature, which results in the electrodes becoming damaged.
Last year, we succeeded in developing a composite electrolyte that not only has good conductivity (2x10-4 S/cm), but is also compatible with the materials used for electrodes (lithium-manganese-oxide as a positive electrode and lithium-titanium-oxide as a negative electrode in our lab). This electrolyte is made mainly from silica, a material with which we have a great deal of experience in the chip industry.
Now the challenge is to combine our 3D electrodes and our silica-based composite electrolyte to produce a genuine 3D thin film solid-state battery. If everything goes to plan, we will have a first demonstration set ready in 2016. And hopefully we will then be able to demonstrate that 3D thin film solid-state batteries are more than just hype and are a real new step forward in battery technology that will enable us to produce ultra-small electronics and batteries that will charge up in no time at all!
Author profile:
Prof Dr Philippe Vereecken is principal scientist Electrochemical storage, imec.
