Quantum Diamond Microscope for Battery Structural Health Monitoring
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-07-11 |
| Journal | ECS Meeting Abstracts |
| Authors | O. A. Kuznetsov, David Glenn, Shuang Wu, Xufan Li, Avetik R. Harutyunyan |
Abstract
Section titled āAbstractāReliable performance and extensive lifespan of EV batteries are crucial for vehicle dependability and safety. Typical EV battery modules consist of hundreds or even thousands of cells, and undetected flaw in even one of them leads to reduced performance and shorter lifespan of the entire module and could even result in catastrophic failures. Advance detection of battery problems and failures would be important for making technology safer, more efficient, and durable. While some of faulty cells are detected and rejected by current quality control methods at the production, formation, and aging stages, some of the defective cells do pass through and could lead to negative outcomes. Developing more comprehensive methods of battery health monitoring and problem detection, both at the production and the utilization stages of a battery life, is of great interest for the industry. Accurate monitoring of the battery state of charge (SoC) during the battery utilization allows optimization of the charge/discharge profiles and could extend battery life by up to 10%, but current monitoring methods lack reliability. Recent advances in magnetic sensing technology create opportunities to characterize and enhance the performance of electronic devices via magnetic current imaging (MCI). Quantum magnetometers based on nitrogen-vacancy (NV) centers operate at room temperature and are capable of detecting leakage magnetic fields from the currents passing through the battery structures during charge/discharge. Scanning of the magnetic sensor in the vicinity of the battery cell yields a map of the vector magnetic field distribution. The custom software then converts the measured magnetic field distribution into a detailed image of the distribution of the current density in the cell structures, and thereby can provide the unique insight about battery conditions and performance evolution. The same technique can also be useful for measuring SoC with high accuracy. EuQlid has developed a quantum diamond microscope (QDM) for magnetic current imaging. This system can operate in a serial scanning mode with an ensemble NV diamond sensing element, with spatial resolution of 100 Āµm, and high sensitivity (< 1 nTĆs 1/2 ) for imaging current sources at larger standoff distance. Intact, new batteries with traditional commercial electrodes with several designs have been scanned by the QDM. The vector magnetic field distribution around the batteries has been mapped, and based on it, the current density distribution inside each battery has been reconstructed, including total amplitude, and X- and Y- components. The reconstructed current patterns in the batteries based on the QDM measurements match well with the theoretical predictions for each type of battery design (number of layers, electrode arrangement, tab positions) and battery state (idle, charging, discharging), clearly demonstrating the potency of the quantum microscope magnetometer for such measurements. Batteries with intentionally introduced defects (āboldā spots on electrodes, delaminations, cuts, metal inclusions, bad welds, etc.) were also produced and scanned by QDM. The current density distributions in the defective batteries were compared with that in intact batteries of the same design. The results suggest that QDM magnetometry is a promising technique for battery structural health monitoring.