Analysis of lithium battery fire prevention strategy
Lithium battery is generally divided into lithium metal battery and lithium ion battery. Lithium-ion batteries are widely used for their rechargeability and high energy density. The safety of lithium ion battery is the bottleneck to restrain the development of lithium ion battery and related industries (such as new energy vehicles). Lithium ion battery internal electrolyte is flammable liquid, electrode is flammable material, lithium battery in overcharge, short circuit, overheating, puncture or collision and other circumstances of heat loss of control, easy to catch fire or even explosion, mobile phone, electric bicycle or electric car caused by battery fire fire cases occur from time to time.
This article shares several fire protection options for lithium-ion batteries.
Introduction to lithium battery fire prevention strategy
Lithium battery fire prevention requires the establishment of a strategic depth of multiple lines of defense. In addition to the battery internal use of non-combustible or non-combustible materials as far as possible to make the battery has essential safety performance, the first line of defense outside the battery is to prevent the occurrence of various causes of battery overheating fire, such as overcharge, short circuit, impact, etc., which requires the safety design of the electrical system.
When the first line of defense is broken through (for example, the battery management system fails to cut off the charging power supply in time in case of a fault), the battery temperature rises, and the temperature sensor or gas and smoke detector in the monitoring system should timely detect the fault and give an alarm to remind the staff to deal with the fault and eliminate the fire inducement. This is the second line of defense.
When failure is not handled in a timely manner and the second defense line is broken through, battery combustion (smearing) cannot be avoided. In this case, the fire control system should restrict combustion to the failed battery box (or box), isolate adjacent unburned batteries and equipment, and avoid isolation from fire. Due to the high temperature of lithium ion battery after the heat loss control, the existing non-water extinguishing agent such as gas, dry powder can not bring down the battery temperature quickly, the extinguishing effect is not ideal. Therefore, the controlled burn-down is a realistic and economical plan for battery fire prevention. This is the third line of defense.
If the fire control fails and the fire situation expands, which poses a serious threat to the safety of personnel and property, it is necessary to start the fixed water-based fire extinguishing system installed in the car or wait for the fire brigade to extinguish the fire.
Generally, the first and second lines of defense are considered by battery manufacturers or electric car manufacturers. As a fire protection professional, we can establish a solid third line of defense for customers, and customize the scheme according to the specific model, specification and performance of the battery. The components used in the scheme come from all over the world, not limited to a certain equipment or material.
Example of lithium battery fire protection scheme
This scheme is simple and easy to use for reference from foreign advanced experience. The main components of fireproof materials used are granular minerals, non-combustible, non-conductive, non-corrosive, safe and environmental protection, extremely light weight, reliable performance and reasonable cost, which can be widely used in the production, storage, transportation and use of lithium batteries in the process of fire fighting. After the lithium battery is heated or overcharged, under the protection of fireproof particles, there is no open fire, no explosion and only white smoke, so the fire situation caused by the lithium battery combustion can be avoided.
Fire prevention principle: isolation of oxygen asphyxiation fire extinguishing, heat absorption cooling. Particle size: 1-4mm particle density: 360kg/m3 dry loose bulk density: 240kg/m3, cover the battery with fireproof particles, only smoke comes out when the battery is heated.
Lithium battery transport fire protection scheme
To ensure the effectiveness of fire control, battery box (or box) can also be installed in the independent fire fighting pipe. The fire extinguishing pipe is broken by heat after the battery catches fire, and automatically releases the fire extinguishing gas to extinguish the battery fire.