The physical properties of electrodes, like wave speed and thickness, are closely correlated with key aspects of battery behaviour. These properties vary with charging and discharging as ions and electrons transport between anodes and cathodes, and they also exhibit abnormal changes as fracture and mechanical failure occur to electrodes. Therefore, measuring these properties provides a direct indication of the state of charge as well as the state of health of the test battery. In this work, we report a reliable and accurate ultrasonic technique for such measurement. This technique is based on the physical phenomenon that the ultrasonic reflections from individual battery internal layers build up to form resonance at a certain frequency, which can be continuously changed by controlling the incident and reflection angles of the ultrasonic wave. The resonant frequency has a nonlinear relationship to the physical properties of the electrodes and the angles (as well as some other easily measurable parameters), which can be utilised to directly determine the physical properties of the electrodes from the angle-dependent resonant frequency obtained with a delicate yet simple experimental apparatus. The resulting properties manifest not only the average physical properties over different electrode layers in the depth direction, but also the variation of these properties across the layers. Hence, the technique marks a significant step of progress in the layer-resolved characterisation of batteries.