We use lithium-ion batteries every day – whether in cell phones, laptops, or even in electric cars. But it also comes with drawbacks. Solid state batteries are safer, charge faster and last longer.
Lithium-ion batteries can store a lot of energy per kilogram of their weight and then reliably release that energy over time. However, mobile energy storage also has drawbacks: it often takes hours to recharge the batteries, and sometimes lithium-ion batteries can catch fire or even explode due to a short circuit, for example.
So scientists are looking for alternatives to the lithium-ion battery. An alternative could be solid state batteries. A study conducted by the Fraunhofer Institute for Systems and Innovation Research ISI in Karlsruhe examined the current state of the research.
The study shows the potential and market opportunities of solid-state batteries, but also the obstacles that still need to be overcome in order for this type of battery to keep pace with classic lithium-ion batteries. Dr. Thomas Schmaltz from ISI coordinated work on the study and was with Jochen Steiner on the SWR2 impetus for interview:
What are solid state batteries and how do they work?
Solid state batteries work in a similar way to classic lithium-ion batteries. The solid-state batteries examined, which will be the first to enter the market in larger quantities, are also based on lithium ions. However, they differ from each other.
Current lithium-ion batteries contain a liquid electrolyte, that is, a liquid component. In solid state batteries, this liquid electrolyte is replaced by a solid called a solid electrolyte.
What are the advantages of solid electrolyte?
On the other hand, you don’t have a flammable liquid that could leak, because these solid electrolytes are usually non-flammable. Of course, there are still other components in the battery that can also cause a malfunction or a fire, but at least one factor will be eliminated.
On the other hand, solid state batteries promise a higher energy density. So you can store more energy in the same mounting space, for the same volume or under the same dimensions.
What other advantages do solid state batteries have? Does a cell phone battery last longer, or can an electric car run longer distances with the same weight?
Yes, this is the goal of the development. Since there is no liquid in the batteries, the longevity, stability and safety of these batteries are assumed to be higher. However, it is currently difficult to release accurate data on this as the development of solid state batteries is still at a relatively early stage.
They are extensively researched, but there are still few technologies ready for the market. Long-term stability cannot be expected at this point.
Are there already market-ready ground batteries?
There are solid batteries that have been on the market for a long time – for example such as very small batteries called micro batteries in electronic components. But they only have to store very small amounts of electricity. For example, they make sure that our computer is working even if it has been turned off for a long time and after that it starts up again. But it is organized somewhat differently in terms of technology.
There are solid batteries already on the market that operate on the basis of solid polymer electrolytes. They are already used on buses, but not very widely yet.
However, there are some limitations. Limiting this, for example, that it only works if you heat it up. This means that you need an operating temperature of 50-80°C, which is not ideal for many areas of application.
For example, it does not make sense to stop the car for a longer time and you have to keep the battery hot so that you can drive in time. This is the reason why solid state batteries are currently used in buses that run more or less continuously.
But there are now solid batteries based on sulfide electrolytes and oxide electrolytes. It has not been widely marketed yet. We expect that to happen between 2025 and 2030.
Are solid state batteries more sustainable than lithium ion batteries?
In the case of solid-state batteries based on sulfide and electrolyte oxide in particular, it is not entirely clear what materials they will actually be in when they are brought to market. For this reason, sustainability cannot be evaluated conclusively. In addition, there is still a question mark behind the production processes – it is not entirely clear how they are actually made. Of course, this also depends on how much energy is used in the production of this battery. I would say as a rough estimate they should be roughly comparable to current batteries.
What role will solid state batteries play in the future?
We see the current classic lithium-ion battery with liquid electrolyte as the dominant technology for at least the next 10 years. However, the battery market will continue to diversify. This means that there will be different techniques. There will be different types of batteries with liquid electrolytes and then also with solid electrolytes.
Depending on the application, one of them will be more suitable. If there is an application that needs high power density, one may be better than the other. If costs are very critical and the battery has to be as cheap as possible, then certain components and a different battery type will be used.
We clearly see that the automotive market is the main driver of battery development and the development of solid state batteries, as well as the main field of application in the medium and long term.