Graphene enhances lithium detection in new INL research

Accurate and stable lithium measurement is essential in many areas, from monitoring lithium levels in patients to improving battery performance in energy storage systems. However, designing sensors that are both precise and robust has remained a challenge.

INL researchers, Olesia Dudik, Renato Gil, and Raquel Queirós, have now shown that incorporating graphene into solid-contact electrodes highly improves lithium detection, paving the way for more reliable, next-generation sensors. Their study was published in Microchemical Journal as part of the NGS–New Generation Storage project.

Solid-contact ion-selective electrodes are advanced sensors that convert the chemical signal of an ion into an electrical signal. A key component is the ion-to-electron transducer, which sits between the ion-selective membrane and the electronic conductor. This layer ensures stable voltage readings, prevents water layer formation,  and improves the robustness of the sensor. Finding the right material for this layer has been challenging because each option behaves differently in terms of electrical performance, surface properties, and stability.

The INL team compared several transducers, including conducting polymer, multi-walled carbon nanotubes, graphene, graphene oxide, and reduced graphene oxide. Their analysis showed that graphene-modified electrodes provided the most electroactive and hydrophobic surfaces, resulting in the highest capacitance and lowest potential drift. In simple terms, graphene acts as a smooth superhighway for the ions’ signal to travel to the electronic system, allowing the sensor to read lithium levels quickly and reliably.

“Graphene’s unique properties make it an excellent transducer for solid-contact lithium-selective electrodes,” explains Olesia Dudik. “It not only improves the sensor’s electrical performance but also contributes to long-term stability, which is essential for practical applications”.

These findings provide valuable guidance for designing next-generation potentiometric sensors. “By using graphene as an ion-to-electron transducer, these electrodes can achieve high sensitivity, reproducibility, and robustness, supporting applications in lithium monitoring for healthcare, battery technologies, and environmental analysis”, concludes Olesia Dudik. The study highlights how careful material selection at the nanoscale can directly improve sensor performance, for more reliable and accessible electrochemical devices.

Text by Catarina Moura, Science Communication Officer
Photography by Rui Andrade, Multimedia Officer