Ultrasonic Testing-Based Method for Segmental Calibration and Quantitative Estimation of the Electrolyte Content in Lithium-Ion Batteries

•A quantitative method is proposed for estimating battery electrolyte content based on ultrasonic testing.•The electrolyte contents in different local areas of the sample batteries are calibrated zone-by-zone.•Accurate model is established to estimate the electrolyte content of batteries with insufficient or excessive electrolyte filling.•Experiments show that the proposed method has an estimation accuracy of 3% and a short detection time within 5 min.