Lithium-ion battery warning

Scientists at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., have developed an inexpensive sensor that can warn of impending catastrophic failure in lithium-ion batteries.

The sensor is based on the researchers’ discovery of an intrinsic relationship between the internal temperature of lithium-ion cells and an easily measured electrical parameter of the cell.

Due to their high energy density, lithium-ion batteries power millions of consumer electronic devices and are the most common type of battery used in hybrid and electric vehicles.

They are also growing in popularity for power grid, military and aerospace applications.

But safety concerns remain a challenge to the industry. Battery malfunction and fires in electric vehicles, mobile phones and laptop computers have been reported. Such failures typically result from thermal runaway, a self-perpetuating condition that occurs once a cell reaches a critical temperature.

It was discovered that a very small alternating current, when applied to a lithium-ion battery at specific frequencies, is modified by the cell in a way that is directly related to the temperature of the critical electrochemical interface between the electrodes and the electrolyte.

The temperature of the protective layers between the electrodes and the electrolyte of the battery can be measured during normal operation.

The sensor operates through a simple electrical connection at the positive and negative terminals of the cell and can operate using power from the battery it is monitoring. With multiplexing circuitry, a single sensor can monitor multiple cells in a battery pack.