Before you understand the electrolyte additives, you need to know what the electrolyte is?
The battery in the new energy vehicle is mainly composed of positive electrode material, negative electrode material, electrolyte and separator. The electrolyte is called the “blood” of the lithium ion battery,it mainly conducts electron between the positive and negative electrodes of the battery.
The electrode material determines the energy density of the battery, and the electrolyte is mostly related to the cycle life, high and low temperature performance, safety etc.
The electrolyte is compounded with lithium salt, solvent and additive,etc..
Although the additive accounts for only 10%-30% of the cost of the electrolyte, but its main function is to improve the conductivity and safety of the electrolyte, and the industry barrier is relatively high.
What electrolyte properties will be affected by additives? The additive of the electrolyte can be described by” dosage is little but effect is great”. Additives can significantly improve certain properties of the battery. For example, it can improve conductivity, overcharge safety, flame retardancy , stability, etc. The use and performance requirements of the battery are different, and the focus of the selection of additives will also change.
At present, the main types of additives include film-forming additives, conductive additives, flame retardant additives, overcharge protection additives, additives to improve low temperature properties, etc.
Future development direction of additives
Power batteries are currently developing towards high energy density trends, and new requirements for electrolytes and additives are also proposed. In the future, the development of high energy density batteries will inevitably be high voltage positive electrodes and silicon carbon negative electrodes. Therefore, it is necessary to develop a matching high voltage positive electrode electrolyte. At the same time, taking into account the high-capacity carbon-silicon anode, avoiding the problem of excessive expansion of the SEI film caused by the volume expansion of the silicon anode during the cycle.