Introduction to the composition of lithium battery electrolyte

The lithium battery electrolyte is the carrier for ion transport in the battery. It is generally composed of a lithium salt and an organic solvent.

Lithium battery electrolyte main components

Vinyl carbonate

Molecular formula: C3H4O3

Transparent colorless liquid (>35 ° C), crystalline solid at room temperature, boiling point: 248 ° C / 760 mmHg, 243-244 ° C / 740 mmHg; flash point: 160 ° C; density: 1.3218; refractive index: 1.4158 (50 ° C); melting point: 35-38 ° C; this product is polyacrylonitrile, polyvinyl chloride Good solvent. It can be used as a spinning solution on textiles; it can also be used directly as a solvent for removing acid gases and as an additive for concrete; it can be used as a pharmaceutical component and raw material in medicine; it can also be used as a plastic foaming agent and synthetic lubricating oil. Stabilizer; in the battery industry, can be used as an excellent solvent for lithium battery electrolyte.

2. Propylene carbonate

Molecular formula: C4H6O3

Colorless, odorless, or light yellow transparent liquid, soluble in water and carbon tetrachloride, miscible with ether, acetone, benzene, etc and it is an excellent polar solvent. This product is mainly used in polymer processing, gas separation process and electrochemistry. In particular, it is used to absorb carbon dioxide from natural gas and petrochemical plants, and can also be used as a plasticizer, a spinning solvent, an olefin and an aromatic extractant.

Toxicological data: No animal poisoning was found in oral or skin contact in animal experiments. Rat oral LD50 = 2, 9000mg / kg.

This product should be stored in a cool, ventilated, dry place, away from fire sources, stored and transported in accordance with general low-toxic chemicals regulations.

3. Diethyl carbonate

Molecular formula: C5H10O3

Colorless liquid, slightly odor; vapor pressure 1.33kPa / 23.8 ° C; flash point 25 ° C (flammable liquid can be volatilized into steam, run into the air. The temperature rises, the volatilization accelerates. When the volatilized vapor and air mixture and When the fire source is in contact with flashing sparks, the short-lived combustion process is called flashing, and the lowest temperature at which flashing occurs is called the flash point. The lower the flash point, the greater the risk of fire.); Melting point -43 °C ; boiling point 125.8 ° C; solubility: insoluble in water, miscible in alcohol, ketone, ester and other organic solvents; density: relative density (water = 1) 1.0; relative density (air = 1) 4.07; stability: stable Hazard label: flammable liquid; main use: used as solvent and for organic synthesis.

1 health hazard

Routes of entry: inhalation, ingestion, percutaneous absorption.

Health hazards: This product is a mild irritant and anesthetic, causes headache, dizziness, weakness, nausea, difficulty breathing, etc. after inhalation. Liquid or high concentration vapors are irritating, oral stimulation of the gastrointestinal tract. Long-term repeated contact with the skin is irritating.

2 Toxicological information and environmental behavior

Toxicity: It is estimated that it can be moderately toxic through the gastrointestinal tract, skin and respiratory tract into the body. The irritancy is greater than dimethyl carbonate.

Acute toxicity: LD501570mg/kg (rat oral); human inhalation 20mg / L (vapor) × 10 minutes, tearing and nasal mucosa stimulation.

Reproductive toxicity: hamster abdominal cavity 11.4mg / kg (pregnant mice), there is obvious teratogenic effect.

Hazardous characteristics: flammable, in case of fire, high heat, it may cause burning. Its vapor is heavier than air and can spread to a relatively distant place at a lower place.

Combustion (decomposition) products: carbon monoxide, carbon dioxide.

3 leakage emergency treatment

Quickly evacuate personnel from the contaminated area to a safe area, and conduct isolation to strictly restrict access. Cut off the fire source. It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and wear fire protective clothing. Cut off the source of the leak as much as possible. Prevent entry into restricted spaces such as sewers and flood drains. Small amount of leakage: absorbed with or other inert materials. It can also be washed with an emulsion made of a non-flammable dispersant, and the washing liquid is diluted and placed in a waste water system. A large number of leaks: building a dike or digging a pit. Cover with foam to reduce steam hazards. Transfer to a tank truck or special collector with an explosion-proof pump, recycle or transport to a waste disposal site for disposal.

4 protective measures

Respiratory protection: Self-priming filter respirators (half masks) are recommended when airborne concentrations are high.

Eye protection: Wear safety glasses.

Body protection: Wear anti-static overalls.

Hand protection: Wear rubber gloves.

Other: Smoking is strictly prohibited at the job site. After work, take a shower and change clothes. Pay attention to personal hygiene.

5 first aid measures

Skin contact: Remove contaminated clothing and wash skin thoroughly with soap and water.

Eye contact: Lift eyelids and rinse with running water or saline. Seek medical attention.

Inhalation: Remove quickly from the scene to fresh air. Keep the airway open. If breathing is difficult, give oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention.

Ingestion: Drink plenty of warm water, induce vomiting, and seek medical attention.

Extinguishing method: Spray water to cool the container and, if possible, move the container from the fire to the open space.

Extinguishing media: foam, dry powder, carbon dioxide, sand.

4. Dimethyl carbonate

Molecular formula: C3H6O3

(dimethylcarbonate, DMC) is a non-toxic, environmentally-friendly and widely used chemical raw material. It is an important organic synthesis intermediate. It contains functional groups such as carbonyl, methyl and methoxy groups in the molecular structure. The kind of reaction performance has the characteristics of safe, convenient, less pollution and easy transportation in production. Because dimethyl carbonate is less toxic, it is a promising “green” chemical product.

DMC has excellent solubility, narrow melting point, wide surface tension, low viscosity, low dielectric constant of medium, high evaporation temperature and fast evaporation rate, so it can be used as a low toxic solvent, industrial and pharmaceutical industries, it can be seen from Table 1 that DMC is not only low in toxicity, but also has the characteristics of high flash point, low vapor pressure and high explosion limit in the air. Therefore, it is a green solvent that combines cleanliness and safety.

5. Methyl ethyl carbonate

Molecular weight: 104.1, density 1.00g/cm3, colorless transparent liquid, boiling point 109 ° C, melting point -55 ° C, is a high-tech, high value-added chemical product that has emerged in recent years, an excellent solvent for lithium ion battery electrolyte It is the latest product that has been extended with the increase of the output of dimethyl carbonate and lithium ion batteries. Because it has both methyl and ethyl groups, it has the characteristics of dimethyl carbonate and diethyl carbonate. It is also a special spice and intermediate, the solvent of the body. Due to the imbalance of methyl ethyl, the product is unstable and unsuitable for long-term storage.

This product should be stored in a cool, ventilated, dry place, stored and transported in accordance with flammable chemicals.

6. Lithium hexafluorophosphate

White crystal or powder with a relative density of 1.50, strong deliquescent, soluble in water, soluble in low concentrations of methanol, ethanol, acetone, carbonates and other organic solvents, Decomposes when exposed to air or when heated. Lithium hexafluorophosphate is rapidly decomposed in the air by the action of water vapor during exposure to air or when heated, releasing PF5 to produce white smoke.

7. Pentafluoride

Molecular formula: PF5

Phosphorus pentafluoride (chemical formula: PF5) is a phosphorus halogen compound having an oxidation number of +5 and containing a three-center four-electron bond. Phosphorus pentafluoride is a colorless malodorous gas under normal temperature and pressure, and it is highly irritating to skin, eyes and mucous membranes. It is a highly reactive compound that produces toxic and corrosive white hydrogen fumes in humid air. Phosphorus pentafluoride is used as a catalyst for the polymerization reaction.

Hazard Mark: Toxic Gas, Inorganic Drugs

Main use: used to generate gas and used as a polymerization catalyst.

1 health hazard

Route of entry: inhalation.

Health hazard: Produces toxic and corrosive hydrogen fluoride in humid air. This product has a strong stimulating effect on the skin, eyes and mucous membranes. It can cause respiratory inflammation and pulmonary edema after inhalation.

2 Toxicological information and environmental behavior

Toxicity: Irritating.

Hazardous properties: Produces white, corrosive and irritating hydrogen fluoride fumes in humid air. It liberates highly toxic corrosive gases in the water, decomposes with alkali.

Combustion (decomposition) products: phosphorus oxide, phosphine, hydrogen fluoride.

3 leakage emergency treatment

Quickly evacuate personnel from the contaminated area to the upwind and immediately isolate them. The small leaks are isolated for 300 meters, and the large leaks are isolated for 450 meters, strictly restricting access. It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and wear anti-virus suits. Cut off the source of the leak as much as possible. Proper ventilation and accelerated diffusion. The leaking container should be properly disposed of, repaired, and used after inspection.

4 protective measures

Respiratory protection: Self-priming filter respirators (full face masks) must be worn when exposed to vapors. Wear an air respirator if necessary.

Eye protection: Protected from respiratory system protection.

Body protection: Wear tape anti-virus clothing.

Hand protection: Wear rubber gloves.

Other: Smoking is strictly prohibited at the job site. Pay attention to personal hygiene.

5 first aid measures

Skin contact: Remove contaminated clothing and rinse with plenty of running water. Seek medical attention.

Eye contact: Lift eyelids and rinse with running water or saline. Seek medical attention.

Inhalation: Remove quickly from the scene to fresh air. Keep the airway open. If breathing is difficult, give oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention.

Fire fighting methods: Firefighters must wear full body fire protection suits. Cut off the air supply. Spray the water to cool the container and, if possible, move the container from the fire to the open space.

Extinguishing agent: dry powder, carbon dioxide.

8. Hydrofluoric acid

This product is subject to the control of the public security department in accordance with the Regulations on the Safety Management of Hazardous Chemicals.

Colorless transparent fuming liquid it is an aqueous solution of hydrogen fluoride gas. It is weakly acidic. Has a pungent odor. It reacts with silicon and silicon compounds to form gaseous silicon tetrafluoride, but it does not corrode plastic, paraffin, lead, gold or platinum. It is miscible with water and ethanol. The relative density is 1.298. 38.2% of hydrofluoric acid is an azeotrope with a total boiling point of 112.2 °C, toxic, minimum lethal dose (rat, abdominal cavity) 25mG/kG. Corrosive, strongly corrosive to metals, glass and silicon-containing objects, inhalation of vapor or contact with the skin can form ulcers that are difficult to heal.

1. Security measures

Leakage: Rapid evacuation of personnel from the contaminated area to a safe area, isolation, and strict restrictions on access. It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and wear acid and alkali protective overalls. Do not touch the spill directly. Cut off the source of leakage as much as possible to prevent entry into restricted spaces such as sewers and flood drains.

A small amount of leakage: mixed with sand, dry lime or soda ash. It can also be rinsed with a large amount of water, diluted in water and placed in the wastewater system.

A large number of leaks: construct a dike or digging pit; use a pump to transfer to a tank truck or a special collector, and recycle or transport it to a waste disposal site for disposal.

2. Fire fighting methods

Flammability: non-combustible

Extinguishing agent:  water spray and foam.

Fire Fighting Precautions: Firefighters must wear oxygen breathing apparatus and full protective clothing.

3. Emergency treatment

Inhalation: Quickly leave the site to fresh air. Keep the airway open. If breathing is difficult, give oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention.

Ingestion: Inadvertently gargle with water, give milk or egg white. Seek medical attention.

Skin contact: Immediately remove contaminated clothing and rinse with plenty of running water for at least 15 minutes. Seek medical attention. Or, immediately remove the contaminated clothing, rinse with chlorpyrifos, if it is a fluorine-containing acid, rinse with hexaflurane. Seek medical attention.

Eye contact: Immediately lift eyelids and rinse thoroughly with plenty of running water or saline for at least 15 minutes. Or use chlorpyrifos eyewash (if it is a fluoride acid, rinse with hexafluoride).

4 physical and chemical properties

Hydrofluoric acid is an aqueous solution of hydrogen fluoride gas, which is a colorless transparent to pale yellow smoking liquid. Has a pungent odor.

It has weak acidity, but the ionization degree when concentrated is larger than that of the rare time and is different from the general weak electrolyte. It is highly corrosive and has serious damage to teeth and bones. It is highly corrosive to silicon compounds. It should be stored in a closed plastic bottle.

It is obtained by dissolving HF in water. Used to engrave glass, clean residual sand on castings, control fermentation, electropolishing and cleaning corrosion of semiconductor wafers (mixed with HNO3). Because the ability to combine hydrogen atoms and fluorine atoms is relatively strong, hydrofluoric acid cannot be completely ionized in water.

Advantages of lithium battery electrolyte:

The electrolyte acts as a conduction electron between the positive and negative electrodes of the lithium battery, and is a guarantee for the high voltage and high specific energy of the lithium ion battery. The electrolyte is generally prepared from a high-purity organic solvent, an electrolyte lithium salt, a necessary additive, and the like under certain conditions and at a certain ratio.

The main electrolytes used in lithium batteries are lithium perchlorate and lithium hexafluorophosphate. However, batteries made of lithium perchlorate have a low temperature effect and are in danger of explosion. They have been banned in Japan and the United States. The battery made of fluorine-containing lithium salt has good performance, no explosion hazard, and has strong applicability, especially the battery made of lithium hexafluorophosphate. In addition to the above advantages, the disposal work of the waste battery in the future is relatively simple and ecologically friendly. The market prospects for this type of electrolyte are very broad.

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