Electronic Cigarette Batteries Spontaneously Explode in Woman’s Pocket

This case involves a middle aged female ex-smoker who purchased extra lithium ion batteries for an e-cigarette. The batteries were manufactured by a company in China, and were specifically marketed as being compatible with the Plaintiff’s electronic cigarette. The individual was driving when the recently purchased batteries exploded and caught fire in her pocket. It is alleged that the batteries was defectively designed or manufactured such that it allowed the lithium ion cells to undergo thermal runaway and explode.

Question(s) For Expert Witness

1. Please discuss your knowledge of the components of the e-cigarette, most notably the lithium ion battery.

2. What is the battery's risk for explosion?

Expert Witness Response E-043105

I have a PhD in Materials Science and Engineering and have been doing research on lithium-ion batteries for more than 10 years, published more than 40 peer-reviewed papers. My research is heavily focused on the safety issues of lithium ion batteries. An e-cigarette normally consists of a mouthpiece on one end and a lithium ion battery on the other end. Between them, there is a cartridge holding liquid "juice" that can be vaporized by a heating element. For most e-cigarettes, the heating element can be activated by a switch on the device. These are the major components of e-cigarettes, although there are some other electronic parts like microprocessor to control the circuit inside the e-cigarette. Lithium ion batteries are rechargeable energy storage devices that consist of cathode, anode, and electrolyte between them. The heating element is an essential part of the e-cigarettes and it is extremely important for the manufacturer to make sure that overheating does not occur. Although overheating of the heating element is an obvious hazard, the thermal runaway of lithium ion batteries poses even more safety concerns. When temperature changes in lithium ion batteries, the ionic conductivity would be affected and short circuit might occur and cause extreme large current and possibly explosion. Similarly, when there is an external mechanical force applied, short circuit might also happen and cause an explosion.