News center
Contact us
Dongguan Ji kerr automation Technology Co., LTD
Telephone：0769-83328418
Fax：0769-83328428
Email：[email protected]
Address：80 Luxi Road, Xixi Village, Liaobu Town, Dongguan City, Guangdong Province
trade news
Home > News center > trade news
News center > trade news
Why do lithium batteries produce gas when overcharged or overdischarged?
Date：2018-04-18 browse：336
Ordinary lithium-ion batteries produce a small amount of gas inside the battery during the charging process,
which is generally absorbed during discharge. If the charging current is too large and often overcharged,
the gas generation will be intensified, and the internal pressure of the battery will increase resulting in swelling.
A slight bulge in the battery is allowed, and avoiding overcharge is the key to reducing the bulge phenomenon.
In the production process of the battery cell liquid injection, the requirement of liquid injection pump is high.
In addition, the chemical properties of lithium are very active, it is easy to burn, when the battery charge and discharge,
the battery internal temperature continues to rise, the gas generated during the activation process expands,
the battery internal pressure increases, the pressure reaches a certain degree will burst, causing leakage, fire,
and even explosion, so it is absolutely important to ensure its safety performance. Lithium batteries are mainly some compounds,
toxicity is not very large, but there is a certain pollution, it is best not to inhale. Of course,
the electrolyte of lithium-ion batteries is mainly composed of alkyl carbonate and ether organic or inorganic lithium salts. Fortunately,
it is low toxicity, as long as you pay attention to ventilation and do not eat it, inhaling a small amount may have dizziness and vomiting symptoms,
immediately to the ventilation to breathe fresh air can alleviate. Serious cases require medical attention.
Lithium battery electrolyte is the carrier of ion transport in the battery. It is generally composed of lithium salts and organic solvents.
The electrolyte plays a role in conducting ions between the positive and negative electrodes of the lithium battery,
which is the guarantee of high voltage and high specific energy of the lithium ion battery.
The electrolyte is generally prepared by high purity organic solvent, electrolyte lithium salt,
necessary additives and other raw materials under certain conditions and in a certain proportion.
1. Vinyl carbonate: Molecular formula :C3H4O3
Clear colorless liquid (>35 ° C), crystalline solid at room temperature. Boiling point: 248℃/760mmHg, 243-244℃/740mmHg; Flash point: 160℃;
Density: 1.3218; Refractive index: 1.4158(50℃); Melting point: 35-38℃; This product is a good solvent for polyacrylonitrile and polyvinyl chloride.
It can be used as a drawing fluid on textiles. It can also be directly used as a solvent for removing acid gas and an additive for concrete;
In medicine can be used as pharmaceutical components and raw materials;
It can also be used as a stabilizer for plastic blowing agent and synthetic lubricating oil; In the battery industry,
it can be used as an excellent solvent for lithium battery electrolyte
2. Molecular formula of propylene carbonate: C4H6O3
Colorless odorless, or light yellow transparent liquid, soluble in water and carbon tetrachloride, miscible with ether,
acetone, benzene, etc. It is an excellent polar solvent. This product is mainly used in polymer work, gas separation process and electrochemistry.
In particular, it is used to absorb carbon dioxide from natural gas, ammonia synthesis raw materials in petrochemical plants,
and can also be used as plasticizer, spinning solvent, olefins and aromatic extraction agent.
Toxicological data: No toxicity was found in animal studies by oral or skin contact. Rat transoral LD50=2,9000mg/kg.
This product should be stored in a cool, ventilated, dry place, away from fire sources, according to the general low-toxic chemical storage and transportation.
3. Molecular formula of diethyl carbonate: C5H10O3
Colorless liquid, slightly odorous; Steam pressure 1.33kPa/23.8℃; Flash point 25℃(flammable liquid can be volatilized into vapor and run into the air.
As the temperature rises, volatilization accelerates. When the mixture of volatile vapor and air can flash sparks in contact with the fire source,
this brief combustion process is called flash ignition, and the lowest temperature of flash ignition is called the flash point. The lower the flash point,
the greater the risk of a fire. ; Melting point -43℃; Boiling point 125.8℃; Solubility: insoluble in water, soluble in alcohol, ketone,
ester and other organic solvents; Density: Relative density (water =1)1.0; Relative density (air =1)4.07; Stability; Hazard Mark 7(flammable liquids);
Main Uses: as solvent and for organic synthesis
① Health hazard
Invasion route: inhalation, ingestion, percutaneous absorption.
Health hazard: This product is a mild stimulant and anesthetic. Inhalation causes headache, dizziness, weakness, nausea, dyspnea, etc.
Liquids or high concentrations of vapor are irritating. Oral stimulation of gastrointestinal tract. Skin irritation caused by prolonged and repeated contact.
② Toxicological data and environmental behavior
Toxicity: Estimated to enter the body through the gastrointestinal tract, skin, and respiratory tract as moderately toxic. More irritating than dimethyl carbonate.
Acute toxicity: LD501570mg/kg(rat oral); Human inhalation 20mg/L(vapor) x 10 minutes, tears and nasal mucosa irritation.
Reproductive toxicity: Hamster abdominal cavity 11.4mg/kg(pregnant mice), has obvious teratogenic effect.
Dangerous characteristics: flammable, in case of open fire, high heat has the risk of burning. Its vapor is heavier than air,
can spread to a considerable distance at a low point, and will lead to a return fire in case of open fire.
Combustion (decomposition) products: carbon monoxide, carbon dioxide.
③ Leakage emergency treatment
Quickly evacuate the personnel from the contaminated area to the safety zone, isolate them, and strictly restrict access.
Cut off the fire. Emergency personnel are advised to wear self-contained positive pressure breathing apparatus and fire protective clothing.
Cut off the source of leakage as much as possible. Prevent access to restricted Spaces such as sewers and flood drains.
Small leakage: absorption with or from other inert materials. It is also possible to scrub with an emulsion made of a non-combustible dispersant,
which is diluted and placed in the wastewater system. Large leakage: build a embankment or dig a pit to contain it.
Cover with foam to reduce steam hazards. Transfer to a tank truck or special collector with an explosion-proof pump for recycling or transport to a waste disposal site.
④ Protective measures
Respiratory system protection: When the concentration in the air is high, it is recommended to wear a self-priming filter gas mask (half mask).
Eye protection: Wear safety glasses.
Body protection: Wear ESD clothes.
Hand protection: Wear rubber gloves.
Others: Smoking is strictly prohibited on site. After work, shower and change. Pay attention to personal hygiene.
⑤ First aid measures
Skin contact: Remove contaminated clothing and rinse skin thoroughly with soapy water and clean water.
Eye contact: Lift eyelids and rinse with running water or saline. Seek medical attention.
Inhalation: Quickly remove from the scene to fresh air. Keep your airway clear. Administer oxygen if breathing is difficult. If breathing stops,
give artificial respiration immediately. Seek medical attention.
Ingestion: Drink enough warm water to induce vomiting and seek medical attention.
Fire suppression method: Spray water to cool the container and move the container from the fire to an open area if possible.
Fire extinguishing agent: foam, dry powder, carbon dioxide, sand.
4. Dimethyl carbonate: C3H6O3
dimethylcarbonate (DMC) is a non-toxic, environmentally friendly and widely used chemical raw material.
It is an important organic synthesis intermediate with functional groups such as carbonyl, methyl and methoxy in its molecular structure,
and has various reaction properties. It has the characteristics of safe use, convenient, less pollution and easy transportation in production.
Dimethyl carbonate is a promising "green" chemical product because of its low toxicity.
DMC has excellent solubility, its melting and boiling point range is narrow, the surface tension is large, the viscosity is low,
the dielectric boundary electric constant is small, and has a high evaporation temperature and faster evaporation speed,
so it can be used as a low toxic solvent for the coating industry and pharmaceutical industry. As can be seen from Table 1,
DMC not only has low toxicity, but also has the characteristics of high flash point, low steam pressure and high lower explosive limit in the air,
so it is a green solvent that integrates cleanliness and safety.
5. Methyl ethyl carbonate
Molecular weight: 104.1, density 1.00g/cm3, colorless transparent liquid, boiling point 107℃, melting point -14℃, is the rise of high-tech,
high value-added chemical products in recent years,
an excellent lithium-ion battery electrolyte solvent,
is with the increase of dimethyl carbonate and lithium-ion battery production and extension of the latest products, because it has both methyl and ethyl,
It has the characteristics of dimethyl carbonate and diethyl carbonate, and is also a solvent for special flavors and intermediates.
Due to the imbalance of methylethyl, the product is unstable and not suitable for long-term storage.
This product should be stored in a cool, ventilated, dry place, according to the provisions of flammable chemicals storage and transportation
6. Lithium hexafluorophosphate
White crystal or powder, relative density 1.50. Strong deliquescence; Soluble in water, but also soluble in low concentration methanol, ethanol,
acetone, carbonate and other organic solvents. Decomposes when exposed to air or heated. When exposed to air or heated,
lithium hexafluorophosphate rapidly decomposes in the air due to the action of water vapor, releasing PF5 and producing white smoke.
7. Phosphorus pentafluoride
Phosphorus pentafluoride (chemical formula: PF5) is a phosphorus halide compound with an oxidation number of +5 phosphorus atoms
and a three-center four-electron bond. Phosphorus pentafluoride is a colorless odor gas at room temperature and pressure,
which has strong irritation to skin, eyes and mucous membranes. It is a highly reactive compound that violently produces a toxic
and corrosive white smoke of hydrogen fluoride in humid air. Phosphorus pentafluoride is used as a catalyst for polymerization.
National standard No. 23022
CAS number 7647-19-0
The Chinese name is phosphorus pentafluoride
The English name phosphoruspentafluoride
Alias phosphorus fluoride
Molecular formula PF5 Appearance and properties A colorless, pungent odor gas that smokes violently in humid air
Molecular weight 126.0 boiling point -84.6℃
Melting point -93.8℃ solubility
Density relative density (water =1)5.81(gas); Relative density (air =1)4.3 Stability Stable
Hazardous label 6(toxic gases, inorganic substances) is mainly used for generating gases and as a catalyst for polymerization reactions
① Impact on the environment
1. Health hazards
Route of invasion: inhalation.
Health hazard: Produces toxic and corrosive hydrogen fluoride in humid air. This product has a strong irritating effect on the skin,
eyes and mucous membranes, and can cause respiratory inflammation and pulmonary edema after inhalation.
Toxicological data and environmental behavior
Toxicity: Irritating.
Hazardous properties: Produces white, corrosive and irritating hydrogen fluoride fumes in humid air.
Decomposition in water releases highly toxic corrosive gases. Decomposition with alkali.
Combustion (decomposition) products: phosphorus oxide, phosphane, hydrogen fluoride.
②. Emergency treatment and disposal methods
First, leakage emergency treatment
Quickly evacuate the personnel from the contaminated area of the leak to the upper wind, and immediately isolate,
isolate 300 meters when a small leak, isolate 450 meters when a large leak, strictly restrict access.
It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and wear protective clothing.
Cut off the source of leakage as much as possible. Reasonable ventilation to accelerate diffusion.
The leak container should be properly disposed of, repaired and inspected before use.
Second, protective measures
Respiratory protection: When possible contact with its vapor, you must wear a self-priming filter gas mask (full cover). Wear an air respirator if necessary.
Eye protection: Respiratory system protection has been protected.
Body protection: Wear a tape anti-poison jacket.
Hand protection: Wear rubber gloves.
Others: Smoking is strictly prohibited on site. Pay attention to personal hygiene.
Third, 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: Quickly remove from the scene to fresh air. Keep your airway clear. Administer oxygen if breathing is difficult. If breathing stops,
give artificial respiration immediately. Seek medical attention.
Fire extinguishing method: fire personnel must wear full body fire protective clothing. Cut off the air source.
Spray water to cool the container and move it from the fire to an open area if possible. Extinguishing agent: dry powder, carbon dioxide.
8. Hydrofluoric acid
This product is controlled by the public security department in accordance with the Regulations on the Safety Management of Hazardous Chemicals.
Colorless transparent smoking liquid. It is an aqueous solution of hydrogen fluoride gas. It is weakly acidic. It has a pungent smell.
It reacts with silicon and silicon compounds to form gaseous silicon tetrafluoride, but does not corrode plastics, paraffin, lead, gold,
and platinum. It is miscible with water and ethanol. The relative density is 1.298. 38.2% hydrofluoric acid is an azeotrope with an azeotrope point of 112.2℃.
Toxic, minimum lethal dose (rats, abdominal cavity)25mG/kG. It is corrosive and strongly corrodes metal, glass and silicon-containing objects.
Such as inhalation of steam or contact with the skin can form more difficult to heal ulcers.
① Safety measures
Leakage: Quickly evacuate the contaminated area to the safety zone, and isolation, strictly restrict access.
It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and acid-alkali protective overalls.
Do not contact spills directly. Cut off the source of leakage as much as possible to prevent entering the sewer, flood drainage ditch and other restricted Spaces.
Small leakage: Mix with sand, dry lime or soda ash. It can also be washed with a large amount of water and diluted into the waste water system.
Massive leakage: build a embankment or dig a pit to contain; Transfer by pump to tank or special collector, recycling or transport to waste disposal site disposal.
② Fire extinguishing method
Flammability: non-combustible
Fire extinguishing agent: mist water, foam.
Fire extinguishing precautions: fire personnel must wear oxygen breathing apparatus and wear full-body protective clothing.
③ Emergency treatment
Inhalation: Quickly remove from the scene to fresh air. Keep your airway clear. Administer oxygen if breathing is difficult. If breathing stops,
give artificial respiration immediately. Seek medical attention.
Ingestion: Wash mouth with water and drink 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. Alternatively, immediately remove contaminated clothing and rinse with difentrin or hexafluorin if it is fluorinated acid. Seek medical attention.
Eye contact: Immediately lift eyelids and rinse thoroughly with plenty of running water or saline for at least 15 minutes.
Or seek medical attention with difentrin eye wash (if fluorinated acid, rinse with hexafluorin).
④ Physical and chemical properties
Hydrofluoric acid is an aqueous solution of hydrogen fluoride gas, colorless transparent to light yellow smoking liquid. It has a pungent smell.
It has a weak acid, but the ionization degree is larger than that of the dilute when concentrated and is different from the general weak electrolyte. Strong corrosion,
serious damage to teeth and bones. Highly corrosive to silicon compounds. Store in an airtight plastic bottle.
It is obtained with HF dissolved in water. It is used for engraving glass, cleaning residual sand on castings, controlling fermentation,
electropolishing and cleaning corroded semiconductor wafers (mixed acid with HNO3). Because hydrogen atoms and fluorine atoms have a relatively strong ability to bond,
hydrofluoric acid cannot completely ionize in water.
Previous：no more
Next：Ceramic injection pump, pump valve material subdivision and performance
