Selecting low-impact materials and manufacturing techniques makes it easier to manage batteries at the end of their useful life. A team has developed a methodology to eco-design batteries, for adapting them to their application and improving recycling. “If any other company wants to eco-design a battery or device, they can come to us or try to follow the methodology,” the scientists point out.

The battery designed by CSIC and BCMaterials is recyclable with paper and cardboard, Carles Tortosa and Marina Navarro

A team from the Barcelona Institute of Microelectronics of the CSIC (IMB-CNM-CSIC), and the Basque Center for Materials, Applications and Nanostructures (BCMaterials), has developed a methodology to eco-design batteries and adapt them to the products in which they will be implemented. It consists of manufacturing batteries considering the life cycle of the element, from the selection of materials to their recycling and final reuse, to guarantee their circularity.

“We take into account what it is going to be used for and where it is going to end up to decide what materials and manufacturing techniques we are going to use. The eco-design of the battery is made for a specific purpose and follows the life cycle of the application it powers,” explains Juan Pablo Esquivel, IKERBASQUE researcher at BCMaterials, formerly at IMB-CNM-CSIC.

A battery that mimics a flower

The scientific team has been perfecting the eco-design of batteries for different uses for years. One of its first designs is the FlowER Battery, which imitates the transpiration principle of a plant to produce energy - it moves the reactants through its microfluidic structure until they (the reactants) are expelled by evaporation and produces energy as a result of the electrochemical reaction in its porous carbon electrodes. The FlowER battery, which can be biodegraded at the end of its useful life following the natural cycle of a plant, was presented in 2022. The company, Fuelium, a CNM spin-off, participated in its development through an MSCA Fellow researcher, Omar Ibrahim, co-author of the article, under the direction of Esquivel.

The results were published in the journal Energy & Environmental Science. 'That article already included operational prototypes of these batteries. The goal has been to develop this technology so it can become a product in the company's catalog. In fact, Fuelium currently markets an eco-designed battery technology for portable diagnostic applications, which we created a decade ago at IMB-CNM,' explains Esquivel.

The team has expanded the methodology and created a smart packaging battery. It is composed of lignocellulosic materials, and includes laser-induced graphene for the generation of the current collectors.

The challenge of smart packaging

Electronics recycling is a growing issue in the digital society and efforts to reduce waste start with its design.

Button batteries are often the power source for the sensors that accompany parcels sent by courier. Typically, neither the adhesive tape nor the tracking sensor can be recycled with the packaging, creating a conflict for recycling. Paper and cardboard, on the other hand, have the highest recyclability rate of all materials, which is around 74% in the European Union (2020), and allows for a high circularity of fibres, which can be recycled up to 25 times.

Of the 229,000 tonnes of portable batteries sold in 2020 in Europe, only 47% were collected for recycling. The aim of the new EU regulation is to increase that figure to 73% over the next decade

On the other hand, according to EU data, of the 229,000 tonnes of portable batteries sold in 2020, only 47% were collected for recycling. The aim of the new EU regulation is to increase that figure to 73% over the next decade.

Thus, researchers have chosen smart packaging as a high-impact scenario to apply this methodology and create an eco-designed battery.

FlowER battery installed in a field. The green stem is a compostable structure and evaporation takes place in the leaves of the flower. / Carles Tortosa

The battery developed by CSIC and BCMaterials has a final format similar to a sticker that is attached to the packaging. Marina Navarro, a postdoctoral researcher at BCMaterials, formerly at IMB-CNM-CSIC, notes that ‘it has been demonstrated in standardised tests that it can be recycled in the blue paper and cardboard container without the need to separate it from the packaging’.

‘The battery is versatile and can be manufactured with different sizes and voltages depending on the specific use to be given, it can work to power devices typically used in this sector, such as electrochromic displays or package tracking locators integrated to the Internet of Things and capable of controlling content parameters such as humidity and temperature,’ adds the scientist.

The substrate also includes a current collector made of laser-induced graphene (LIG) as a ‘sustainable alternative to metals commonly used in batteries because of its high electrical conductivity and chemical stability’.

If graphene were processed in other ways, such as in inks, ‘it would require more chemical reagents that we would then have to separate and eliminate in a higher energy consumption, which would result in a more polluting and less circular manufacture’, concludes Iñigo Martín, a researcher at IMB-CNM-CSIC.

'If any other company wants to eco-design a battery or electronic device they can come to us or try to follow the reported methodology. We are convinced that this is the way forward, so the more developers adopt it, the better'

A first guide for eco-designing batteries

The methodology offers a first guide to start eco-designing power supplies, with the aim of making it a scalable technology in the future and reducing e-waste in the sector.

‘If any other company wants to eco-design a battery or electronic device they can come to us or try to follow the reported methodology. We are convinced that this is the way forward, so the more developers adopt it, the better,’ Esquivel says.

The work started with Marina Navarro's thesis at IMB-CNM, supervised by Esquivel, and a collaboration she initiated in Germany after receiving the PoLiS Cluster of Excellence award for young researchers, funded by the German Research Foundation (DFG). It includes the collaboration of Manuel Baumann and Marcel Weil from the Karlsruhe Institute of Technology; Marie Curie Fellow Omar Ibrahim and research assistant Carles Tortosa at the IMB-CNM spin-off Fuelium, co-founded by Esquivel; Iñigo Martín's contribution to graphene technology; and the participation of IMB-CNM TFG student Joseba M. Ormaetxea.