Analysis of Safety Hazards of Lithium Batteries

Energy-saving and environmentally friendly new energy vehicles are a direction of development in the automotive industry.

Batteries, as energy storage components and power sources for new energy vehicles, play a core role in new energy vehicles. Lithium batteries have been widely used in the field of new energy vehicles due to their advantages such as high energy density, low self-discharge rate, and long cycle life. However, due to factors such as imperfect application environment, battery materials, and production processes, battery packs will have problems such as reduced energy efficiency, shortened life, and reduced driving range of electric vehicles, and even lead to combustion and explosion accidents, posing safety hazards.

Lithium-ion batteries are generally composed of positive electrodes, negative electrodes, positive electrode leads, negative electrode leads, central tubes, diaphragms, electrolytes, and battery shells. The positive electrode of the battery is a metal oxide, a doped compound, etc., the negative electrode of the battery is a carbon material, and the battery electrolyte is composed of an inorganic lithium salt and an organic solvent. Lithium batteries are secondary batteries, and the battery is charged and discharged by the movement of lithium ions between the positive and negative electrodes.

Lithium batteries are divided into cylindrical lithium batteries and square lithium batteries, and are further divided into aluminum shell lithium batteries, steel shell lithium batteries and soft pack lithium batteries according to the different battery packaging materials.

The safety accidents and recall data of lithium batteries at home and abroad in recent years show that the safety accidents of lithium-ion batteries are mainly manifested as overheating, combustion and explosion. The main cause of safety accidents of lithium-ion batteries is heat accumulation or thermal runaway, which is manifested as the inability to dissipate heat normally and in time or the sudden increase of local pressure, which leads to battery runaway, causing fire, explosion and other accidents, which will threaten personal safety to a certain extent. Internal materials, manufacturing processes, abnormal use, fatigue and other factors may cause battery failure.

The production of lithium batteries includes multiple complex processes such as pole piece production, battery cell assembly, and post-processing. During the production process, more than a dozen defects such as scratches, particles, edge damage, pole piece perforation, etc. may occur. Therefore, before leaving the factory for use, lithium batteries need to be defect-detected to evaluate their safety performance.