Electrolytic composition
Mainly includes electrolytes, solvents and additives.
Electrolyte
The lithium salt used in the electrolyte, that is, various lithium-containing compounds, releases a large number of active lithium ions after being dissolved in the solvent. Commonly used lithium salts include LiPF6, LiClO4, LiBF4, LiBOB, LiTFSI, LiAsF6, etc. Among them, LiPF6 is currently a relatively mature commercial lithium salt.
These lithium salts each have their own advantages and disadvantages. In actual use, LiPF6 is often used as the main one, and other types are added in appropriate quantities to achieve their advantages and improve the performance of the electrolyte. .
Solvent
Lithium batteries generally use organic solvents. The potential of the negative electrode of lithium-ion batteries is very close to that of lithium et is not sufficiently stable in aqueous solution systems. This is why organic solvents are used as ion carriers.
Common types of solvents for lithium battery electrolytes include carbonates, ethers, and hydroxy acid esters.
In order to improve the conductivity of the electrolyte, it is theoretically appropriate to choose a solvent capable of supplying as many active lithium ions as possible to the solution, i.e. the solubility of the electrolyte it contains is high, and the degree of dissociation of the solute molecules must also be high; the dielectric constant of the solvent is high and the viscosity is low. In fact, solvents with high dielectric constants also have high viscosity and should be selected based on actual conditions.
Additives
Additives refer to a small amount of substances added to the electrolyte in addition to the solute. It generally cannot store electricity. The purpose of adding them is to improve the performance of. The electrolyte and improves the stability of the cell.
In order to improve the purity of the electrode solution and improve the stability of the battery, professional battery electrolyte filtration equipment is generally used to professionally filter the electrolyte. And often, the electrolyte is made up of several stages of the filtration process.
Electrolyte filtration equipment
Lithium battery electrolyte
Inhale the lithium electrolyte and dissolve it as follows.
1. Avoid contact quickly: leave the area as much as possible and go to a ventilated area to breathe fresh air.
2. Rinse your mouth: Rinse your mouth with warm water and spit out any remaining lithium electrolyte into your mouth.
3. See a doctor immediately : If serious reactions occur, such as shortness of breath, body chills, dizziness, etc., it is recommended to consult a doctor immediately for prompt treatment.
The electrolyte in lithium batteries is an important component of the battery and has a significant impact on battery performance. In traditional batteries, the electrolytic system uses water as a solvent. However, since the theoretical voltage of water decomposition is only 1.23 V, even taking into account the overpotential of hydrogen or oxygen, the maximum voltage of a battery with an electrolytic system using water as a solvent is only about 2V (like a lead acid battery). acid battery). The voltage of lithium batteries reaches 3~4V. The traditional aqueous solution system is obviously no longer suitable for the needs of batteries, and a non-aqueous electrolyte system must be used as the electrolyte of the batteries.lithium-ion batteries. The electrolytes in lithium batteries are mainly those that can withstand high voltages without decomposing.Organic solvents and electrolytes.
The electrolyte used in lithium-ion batteries is an ionic conductor with electrolytic lithium salt dissolved in an organic solvent. Generally, as an organic electrolyte for practical lithium-ion batteries, it should have the following properties:
(1) High ionic conductivity, generally reaching 10-3~2*10-3S/cm lithium ion; the migration number should be close to 1;
(2) The potential range of electrochemical stability is wide; there should be an electrochemical stability window of 0~5V;
(3) Good thermal stability, wide operating temperature range;
(4) Chemical properties are stable and do not react chemically with the current collector and mild substances present in thea battery;
(5) Safe and low toxicity, preferably biodegradable.
Suitable solvents should have a high dielectric constant and low viscosity. Commonly used solvents include alkyl carbonates such as PC and EC, which are highly polar and have a high dielectric constant, but have high viscosity and intermolecular forces. , lithium ions move slowly there. Linear esters, such as DMC (dimethyl carbonate) and DEC (diethyl carbonate), have a low viscosity but also a low dielectric constant. Therefore, in order to obtain a solution with high ionic conductivity, they are generally used PC+DEC, EC+DMC. and other mixed solvents. These organic solvents have some odor, but generally speaking, they can meet EU RoHS and REACH requirements. They are very toxic, environmentally friendly and environmentally friendly materials.ement.
The currently developed inorganic anion conductive salts mainly include three categories: LiBF4, LiPF6 and LiAsF6. Their electrical conductivity, thermal stability and resistance to oxidation are in the order:
Conductivity: LiAsF6≥LiPF6. >LiClO4>LiBF4
Thermal stability: LiAsF6>LiBF4>LiPF6
Oxidation resistance: LiAsF6≥LiPF6≥LiBF4>LiClO4
LiAsF6 has conductivity and very high stability and charge and discharge rates of batteries, but its application is limited due to arsenic toxicity. Currently, LiPF6 is most commonly used.
All materials of currently commonly used lithium batteries, including electrolytes, comply with EU RoHS and REACH requirements and are environmentally friendly energy storage products.