What requirements should lithium-ion battery electrolytes meet?
Back
2024/03/12 11:43:49
An electrolyte is a compound that is dissolved in an aqueous solution or can conduct electricity on its own in a molten state, and can dissociate into freely moving ions when dissolved in water or heated. Electrolyte is an important part of lithium-ion battery, which plays the role of transporting ions and conducting current between the positive and negative poles.
Electrolyte as a key material of lithium-ion battery affects and even determines the specific energy, life, safety performance, rate charge and discharge performance of the battery, as a practical electrolyte for lithium-ion batteries should meet the following conditions:
1, lithium ion conductivity: the electrolyte does not have electronic conductivity, but must have good ionic conductivity, in the general temperature range, the conductivity of the electrolyte is between 1×10-3~2×10-3S/cm. As an electrolyte, it must have excellent ionic conductivity and electronic insulation, so that it can play the function of the ion transport medium, while reducing its own self-discharge.
2, ion migration number: lithium battery internal transport charge depends on the migration of ions, high ion migration number can reduce the concentration polarization of electrode reaction, so that the battery produces high energy density and power density. The ideal lithium ion migration number should be as close to 1 as possible.
3, stability: when the electrolyte is in direct contact with the electrode, the occurrence of side reactions should be avoided as far as possible, which requires the electrolyte to have a certain chemical stability and thermal stability.
4, mechanical strength: lithium-ion battery electrolyte needs to have a high enough mechanical strength to meet the mass production of battery packaging process. Li and so on will be trimethyl phosphate ester (TMP) as a high voltage electrolyte additives, with Li1.2 Mn0.54 Ni0.13 Co0.13 O2 as the positive pole of the battery and test, results show that adding 1% TMP, electrolyte can significantly improve the performance and cycle performance of battery.
5, excellent mechanical properties: due to direct contact with the positive and negative electrodes, the polymer lithium battery electrolyte should have strong toughness, and can withstand changes in stress during battery assembly, storage and use, and cannot be brittle. At the same time, when used as a diaphragm, it should also have considerable mechanical strength to inhibit the generation and piercing of lithium dendrites and prevent short circuit of positive and negative electrodes.
Previous
