7 Tesla Magnetic Resonance Image Radio-Frequency Coils for Measuring Lithium-Ion Battery Cell Performance

In recent years, studies have been conducted to confirm the battery charge/discharge state using a magnetic resonance (MR) system. However, due to the structural characteristics of the battery, some difficulties exist in acquiring the signal. For example, because a loop coil does not coincide with the battery cell structure, non-uniform areas exist inside the cell samples, and it works as a limit to acquiring a quantitative MR signal measuring from the pack of lithium-ion batteries (LIB). In addition, the radio-frequency (RF) signals are weakened by the aluminum layer of the cell package. In this paper, we proposed a planar RF coil to obtain uniform ¹H and SUP7/SUPLi signals from this shielding-packaged battery cell in 7 Tesla (T) magnetic resonance image (MRI). To demonstrate the usefulness of the proposed planar RF coil, we designed a loop coil for ¹H and SUP7/SUPLi, a planar coil for ¹H, and a cut coil for ¹H and SUP7/SUPLi. Then the performance of each coil was compared through a bench test. The water phantom image was acquired with each coil, and the signal intensity profile and signal-to-noise ratio (SNR) were calculated and compared. The ¹H/SUP7/SUPLi images and spectra of the electrolyte phantom were obtained using the cut coils, and the results were compared with the phantom.