Bio-battery: More sustainability for the Internet of Things

You have developed a "biodegradable battery". Can you explain in a few sentences what that means in technical terms?
It's not a battery in the common sense of the word. It's actually a supercapacitor. Capacitors can be charged very quickly and repeatedly, but they also discharge quickly again. The trick, in a nutshell, is that we use carbon particles to store charge on electrodes and that the whole construct is created from a single cast in a 3D printer, which assembles the capacitor from various layers of completely biodegradable material.

In addition, we are also working on a primary battery based on a similar principle, which can only be used once and, depending on the needs, provides either a constant small amount of energy over a longer period of time or a little more power in a shorter period of time.

What is the background to this idea?
I have personally already done a lot of research in this area – with conductive polymers or organic-based battery systems. But what I always found a pity, is: So far, none of these solutions managed to get by entirely without a toxic element. So I wanted to take this last step and develop a battery with exclusively biodegradable components. Because I am convinced that such a solution can make an important contribution to the environment in today's world and be part of a larger vision.

What kind of vision are you talking about?
My department at Empa is called "Cellulose & Wood Materials". Thus, the focus of our research does not, as perhaps the development of this battery would suggest, lie solely on the "energy aspect". We are looking much more broadly for new ways in which sustainable materials can increasingly find their way into technology or other areas. This is exciting, but also difficult. The performance has to be right for something to catch on and be used in applications. With our completely biodegradable battery, we have taken a big step in this direction.

Exactly, the impact will probably be decided, among other things, by the areas of application and the performance of the battery. How does it stand in this respect?
We are talking here about batteries with rather low power, for example for sensors. The applications that need these batteries have increased significantly in the last 10 to 20 years – especially in the area of the Internet of Things (IoT), for instance in logistics monitoring. We are already running a project there. It is called "GREENsPACK" for Green Smart Packing in transport logistics. So we didn't just start developing out of the blue, we knew that there were actually areas of application for this technology.

Apart from logistics monitoring, what are the concrete areas of application?
Our invention is also interesting for food and environmental sensor technology. Hundreds or thousands of sensor systems could be placed somewhere in the forest or in a field, for example, and even be left there without polluting the environment.

So, for example, you could use it to equip sensors in forests to warn of forest fires?
Yes, exactly, environmental sensors for forests would be a possibility, but the exact concept still needs to be further developed and tested.

What are the areas of application for the primary battery for single use mentioned above?
It is suitable, for example, in the biomedical field for disposable systems such as test kits, which would then be biodegradable and not cause any environmental pollution during disposal. Think of situations such as the current Corona pandemic, where certain technology is needed on a large scale and –  for understandable reasons –  even on a one-off basis. Our development could be very useful there and contribute a lot to reducing environmental pollution.

Could your development be produced on a large scale?
In our printing process, we deliberately do not work under special conditions or in normal atmospheric conditions. That is the prerequisite for having a result that can be produced as simply, efficiently and scalably as possible.

Could it one day replace classic batteries in our everyday lives?
In our everyday life, there are mainly applications that are designed for standard batteries. That is not our primary starting point. It goes more in the direction of a completely printed system in which the energy component is one part and the sensor technology or the system itself is the other – or in other words: solutions developed for very specific needs.

Nevertheless, it is going in the direction of marketability ...
Yes. Our research results have already aroused interest from industry. I can't reveal too much yet, but we are in talks for projects with potential partners. It is about processing existing products to make them as "green" as possible, but also about completely new functionalities of material that are made possible by our energy component.

Many companies are becoming increasingly aware of the environmental aspect. How do you assess the potential for more companies to want to develop in this direction?
I think the potential is great. However, one must not forget that we are really talking about "low power" applications. We are using materials practically straight from nature, so the performance is limited somewhere. A high-power battery is not realistic. But many applications are also becoming more economical in terms of energy consumption and, accordingly, the overall potential of bio-based batteries is increasing.

You spoke of your vision at the beginning. What is your wish for this development? What do you want to achieve with it in the next few years?
Basically, I am already happy about the fact that we are stimulating discussions about how important and useful research and development are in this field. On the other hand, I am pleased to see that the battery is now increasingly being used in applications. If you think about logistics, with millions upon millions of packages, our invention would not have such a big impact on each individual one, but it would on the overall volume. At the end of the day, what I want is to contribute to a better, sustainable world.