3.2 Ionic conductivity of electrolyte
Lithium ions play a race in anode/anode materials, but the race in electrolytes is swimming.
Lithium ions bounce back and forth between the anode and the cathode, swimming in a “swimming pool” of electrolytes and battery shells. The ionic conductivity of the electrolyte, like the resistance of water, has a great influence on the speed at which lithium ions swim. At present, organic electrolytes used in lithium ion batteries, no matter liquid electrolyte or solid electrolyte, have low ionic conductivity. The resistance of electrolyte becomes an important part of the battery resistance, and its influence on the high rate performance of lithium ion battery cannot be ignored.
In addition, we should focus on chemical and thermal stability of electrolytes. If the chemical stability of the electrolyte is not good, it is easy to oxidize and decompose on the surface of the cathode material, affecting the ionic conductivity of the electrolyte. The thermal stability of electrolyte has a great impact on the safety and cycle life of lithium ion battery, because a lot of gases will be generated when the electrolyte is decomposed by heat. On the one hand, it is a hidden danger to the battery safety, and on the other hand, some gases will destroy the SEI film on the negative electrode surface, affecting its cycle performance.
Different materials and different shapes of conductive agents will affect the internal resistance of batteries. This affects battery magnification.
The wetting degree of electrolyte and anode materials will affect the contact resistance at the interface between electrolyte and electrode, thus affecting the rate performance of the battery. The total amount of electrolyte, viscosity, impurity content and porosity of anode and cathode materials will change the contact impedance between electrolyte and electrode, which is an important research direction to improve the rate performance.