Energy: ENEA pioneering batteries printed with rotogravure technology

ENEA has printed lithium-ion and sodium batteries for the first time using the “rotogravure” technique, widely used in the packaging industry and in printing newspapers, magazines and currency. Some of the results of these applications have been published in Batteries ^[1] and could contribute to more sustainable and potentially cheaper battery production for their potential to reduce material and energy consumption.

Indeed, this technique combines high productivity with high print quality, which make it ideal for the production of small rechargeable batteries for portable and wearable electronics. The activity was funded by Electric System Research 2019-2021 and 2022-2024 and Mission Innovation, with new funding also planned in the three-year Electric System Research Plan 2025-2027.

 “The process is particularly suitable for creating thin, uniform functional layers over large surfaces and for studying new materials, in which the choice of the deposition method  is just as important as the material being printed” explained study coordinator Maria Montanino, researcher at the ENEA Technologies and Devices for Electrochemical Storage Laboratory of the Energy Technologies and Renewable Sources Department.

The need to use very dilute inks ^[2] has so far made gravure printing uninteresting for the battery industry: but ENEA researchers have achieved high quality printing by developing inks balancing viscosity and mass loading ^[3].

After printing electrodes for lithium batteries, ENEA researchers have also extended the technique to sodium ion batteries ^[4], a promising alternative due to the abundance and low cost of sodium compared to the more expensive and ‘critical’ lithium. Rotogravure-printed anode production using hard carbon as material has also been explored.

 "We chose this material because of its strength and stability characteristics that are essential for prolonging battery life. Prolonged grounding (about 3 hours) of this material leads to a more uniform structure that improves the battery charging/discharging process. This means that we will need to focus on refining the material and optimizing the porosity of the printed layer to increase the efficiency of the oxidation-reduction, i.e., charge/discharge process. We will continue to refine the materials and optimize the process, also to facilitate the implementation of gravure printing in the industrial production of rechargeable batteries," Montanino concludes. 

[1]  For printing sodium batteries: https://www.mdpi.com/2313-0105/10/11/407

[2] Viscosity less than 100 milliPascal-second (mPa-s).

[3] Amount of active material contained in the electrode per unit area.

[4] In detailing the numbers, early results of the ENEA study show that the printed anode of the sodium-ion battery has an initial energy storage capacity of 400-440 milliampere-hours per gram (mAh/g), later stabilizing around 120 milliampere-hours per gram (mAh/g) for more than 100 cycles after material optimization.