The thermal stability of lithium -ion battery and overcharge, high temperature and short -circuit safety analysis summary!energy storage battery 48v lithium ion battery

　　Lithium ion batteries are mainly composed of negative electrode materials, electrolytes and positive poles. The chemical activity of the litter of the negative material is close to the metal lithium during charging state. The SEI membrane on the surface at high temperature is decomposed. The lithium ion and electrolytic solution, and the adhesive polar vinyl of the graphite will react to a large amount of heat.

　　Electrolytic solution is generally adopted by alkyl carbonate organic solution, which is flammable. The positive electrode material is usually a transition metal oxide. It has strong oxidation properties during charging. It is easy to decompose oxygen at high temperature. The oxidation and electrolytes released by the release of the oxygen and electrolytes are released, and a large amount of heat is released.

　　Therefore, from the perspective of materials, lithium -ion batteries have strong danger, especially when abuse, safety issues are more prominent.

　　1. Analysis of thermal stability of lithium -ion battery material

　　The fire risk of lithium -ion batteries is mainly determined by chemical reactions in the inside of the battery. The fire risk of lithium -ion batteries depends on the thermal stability of the battery material, and the thermal stability of the battery material depends on the chemical reactions between the internal parts. At present, people mainly use the differential scanning heat meters (DSC), thermal analyzer (TGA), thermal heating acceleration heat meter (ARC), etc. to study the thermal stability of battery -related materials.

　　1 The influencing factors of the thermal stability of the negative pole material:

　　The starting temperature of the maintenance of the negative material increases with the increase of the particle size.

　　Use DSC to study the thermal stability of the lithium -embedded natural graphite of different particles. It was found that there were three hot peaks in all samples. The first peak of the sample was located near 150 ° C. The position of the latter two peaks was obviously different. The start temperature of the latter two peaks increased with the size of the particle size. The study showed that the first split peak was the decomposition of the SEI membrane, and the latter two hot peaks reaches the reaction of lithium graphite with PVDF and electrolyte.

　　The relationship between the surface area and thermal stability of graphite materials was studied with ARC. It was found that when the surface area of graphite materials increased from 0.4 square meters/gram to 9.2 square meters/gram, the reaction rate increased by two orders of magnitude. Therefore, the reaction rate of carbon negative materials increases with the increase of the surface area.

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