Battery (electricity)

Quantum mechanics

Engineering

State of charge

Lithium (medication)

Materials science

Chromatography

Endocrinology

Ultrasonic sensor

Power (physics)

Acoustics

Thermodynamics

Physics

Organic chemistry

Electronic engineering

Electronics

Analytical Chemistry (journal)

Charge (physics)

Medicine

Chemistry

Electrode

Anode

Optoelectronics

Electrical engineering

Journal of Power Sources

For electrically powered applications such as consumer electronics and especially for electric vehicles a precise state-of-charge estimation for their lithium-ion batteries is desired to reduce aging, e.g. avoiding detrimental states-of-charge. Today, this estimation is performed by battery management systems that solely rely on charge bookkeeping and cell voltage measurements. In the present work we introduce a new, physical probe for the state-of-charge based on ultrasonic transmission. Within the simple experimental setup raised cosine pulses are applied to lithium-ion battery pouch cells, whose signals are sensitive to changes in porosity of the graphite anode during charging/dis-charging and, therefore, to the state-of-charge. The underlying physical principle can be related to Biot's theory about propagation of waves in fluid saturated porous media and by including scattering by boundary layers inside the cell.

Probing lithium-ion batteries' state-of-charge using ultrasonic transmission – Concept and laboratory testing