Use of ultrasound for estimating state of charge and state of health in lithium-ion batteries.

As a battery goes through charge and discharge cycles, lithium-ions are transferred between the anode and cathode layers causing a change the density distribution of the cell. The aim of this work is to look into the use of ultrasound to track these changes in density with the intention of gaining state of charge and state of charge of health information that could be utilised in a battery management system.

Briefly. Change in density distribution using ultrasound has been proven to work as a concept in literature previously and has been successfully recreated in preliminary tests. A particular aim of this work is to gain as much information as possible from responses to ultrasound pulses such that a collection of samples have the possibility of providing useful battery diagnostic information. Regardless of the history, manufacture and condition of the cell.

Part of this work is to explore the changing of surface texture in the electrodes as they age. This could provide critical state of health information with the batteries ability to accept charge.

Battery management systems are a large and varied area of current research. Ultrasound is a relatively small area within this field. The benefits of this technique are due to the non-invasive and non-destructive nature of ultrasound explorations. Information about a closed cell can be obtained using this method that can provide real time data for analysis. Much of the current state of battery management is based on estimation techniques and as such, more accurate methods are sought.

Batteries are becoming more popular in high power applications such as electrical vehicles and aerospace applications. This demands the safe use of batteries and accurate battery management systems become critical for safe and efficient usage.