The ability to detect and quantify the state of charge (SoC) of lithium-ion (Li-ion) batteries - the most common energy sources for portable devices - using fast and nondestructive evaluation techniques is crucial for the technology. Ten factory-new 18650 batteries were imaged at 100% and 0% SoC using a Vantage-256 system (Verasonics, Inc.) equipped with a 5-MHz and 64-element ultrasound array (Imasonic SAS). Quantitative ultrasound spectroscopy (QUS) parameters, i.e., midbandfit (MBf), spectral slope (SS), and intercept (I0), were obtained from the normalized power spectra of the backscattered ultrasound signals. A significant impact (ANOVA, p<0.05) of SoC on two spectral parameters (i.e., MBf and SS) was observed. The results from this study demonstrate feasibility and promising results of using linear-array ultrasound transducers in combination with QUS parameters for future nondestructive evaluation of SoC of Li-ion batteries.