Lithium batteries are generally divided into lithium metal batteries and lithium ion batteries. Lithium ion battery is widely used because of its high energy density. The safety of lithium ion batteries is the bottleneck of the development of lithium ion batteries and related industries (such as new energy vehicles). The internal electrolyte of lithium ion battery is a flammable liquid, the electrode is combustible materials, lithium batteries in overcharge, short circuit, overheat, puncture or collision under the condition of thermal runaway, easy to fire or explosion, mobile phone, electric bicycle or electric car batteries for fire fire cases have occurred.
The author set 20 years working experience in fire industry, and with domestic and foreign counterparts extensive exchanges, from the beginning of 2012 of fire electric bicycle and an electric vehicle lithium ion battery, the lithium ion battery for the share of several fire scenarios.
Brief introduction of fire protection strategy for lithium battery
Lithium battery fire needs to establish a strategic depth of multi line defense. In addition to the internal battery as far as possible the use of non combustible or refractory material for battery with intrinsically safe performance, the first line of defense outside of the cell is to prevent the occurrence of various incentives lead to overheating of the battery fire, such as overcharge, short-circuit and impact, which requires safety design of electrical system.
When is the first line of defense after the break (such as a battery management system failure failed to cut off the charging power supply), battery temperature, temperature sensor and control system of gas or smoke detectors should be detected and fault alarm, to remind the staff to deal with the fault, eliminate the fire causes. This is the second line of defense.
When the failure is not timely treatment, second line break after the burning of the battery (smoldering) have been unable to avoid the fire protection system to do now is to limit the combustion in the battery box fault (or box) in (containment), battery and equipment without fire and can isolate adjacent, to avoid the spread of fire (isolation). Because the temperature of lithium ion battery is out of control, the existing non water extinguishing agent, such as gas and dry powder, can not reduce the temperature of the battery quickly. Therefore, it is a more realistic scheme to set the fire protection target of the battery to burn-down (controlled). This is the third line of defense.
If the fire control failure of the fire expanding, poses a serious threat to the security of people, you need to start the fixed water-based fire extinguishing system installed in the vehicle or waiting for the fire brigade to put out a fire. well fire tarden messures also taken in these batteries: