With the development of the new energy industry, taking new energy vehicles as an example, it also faces many problems such as insufficient stability of lithium-ion batteries, high manufacturing costs, and environmental pollution. Lithium is currently the most active metal element. As long as it is exposed to air, it undergoes violent oxidation and redox reactions with oxygen. Therefore, once the quality of the lithium-ion battery is not up to standard, it will not only spontaneously ignite, but also explode due to the accumulation of heat after heating.
In short, whether in the process of charging and discharging or in a static state, lithium-ion batteries may cause spontaneous combustion or explosion due to internal temperature rise, uneven temperature between single cells, etc., and are very unstable. In order to solve this problem, over the years, R&D personnel have tried various means, such as designing a built-in flame retardant to make the lithium solar cell electrolyte have better resistance to impact damage; or using a water-based electrolyte that will not catch fire, Avoid low voltage and low energy density due to water stability.
At present, new energy vehicles mainly use ternary lithium solar cells, and some models use lithium iron phosphate solar cells, all of which are liquid lithium-ion batteries. But for this kind of battery, although the energy density is higher than that of the previous nickel-metal hydride battery, there is still heat generation. Taking a pure electric vehicle as an example, charging with a fast charging pile for a long time will aggravate the chemical reaction inside the battery and cause heat generation. In severe cases, thermal runaway can occur.
The reason for the difficulty of progress in lithium solar cells is not only the heat generation phenomenon, but also the materials. Currently, lithium is the most suitable electrode, which has led to optimization of the material of the other electrode, improved electrolyte and separator. For example, it can reduce the resistance of the separator, increase the conductivity, and expand the lithium ion transmittance, thereby improving the overall energy density and stability. But this method has little room for operation and limited progress every year.
The fire hazard of lithium-ion batteries is mainly determined by the heat generated by the chemical reactions of various parts of the battery. Ultimately, the fire hazard of a lithium-ion battery depends on the thermal stability of the battery material, which depends on the chemical reactions between its internal parts. At present, people mainly use differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA) and adiabatic acceleration calorimeter (ARC) to study the thermal stability of battery-related materials.
