Rechargeable batteries are at the heart of many new technologies, for example, the increasingly popular renewable energy sources. More specifically, they are used to power electric cars, telephones, and laptops.
The University of Mainz and the Helmholtz Institute in Germany have recently demonstrated a contactless method to detect the state of charge of lithium-ion batteries and any potential defects in them. For this purpose, an atomic magnetometer was used to measure the magnetic field around the battery. Prof. Dmitri Badek and his team usually use atomic magnetics to explore fundamental problems in physics, such as the search for unknown particles. Magnetics is the term used to describe the measurement of magnetic fields. A simple example of an application is the compass, where the Earth's magnetic field causes it to point north.
The demand for high-capacity rechargeable batteries is growing, so a sensitive and accurate measurement technique is needed to determine the state of the battery. The development of many new technologies will depend on the ability to produce batteries that provide sufficient capacity and long active life. "Ensuring the quality of rechargeable batteries is a major challenge, and our non-contact inspection method promises to improve batteries," said Dr. Yahn Wickenbroek, one of the researchers. The research team made the breakthrough by using an atomic magnetometer to make the measurements.
Says Wickenbrook, "Our technique is basically the same as MRI, but much simpler because we're using an atomic magnetometer." Atomic magnetometers are light-pumped magnetometers that use gaseous atoms as magnetic field probes. They are commercially available and can be used for industrial applications as well as basic research.
A simple method for fast, high-throughput measurements
In the case of cell measurements, the cell is placed in a background magnetic field. The cell changes the background magnetic field and with the atomic magnetometer, we are able to measure this change. This change gives us information about the battery's state of charge, the amount of charge left in the battery, and possible damage," Wickenbrook added.
The team said the technology's detection capabilities are expected to be used for research, quality control or evaluation of batteries during operation. The paper was published in the Proceedings of the National Academy of Sciences (PNAS).
