Why will the lithium ion battery explode? Depth analysis of safety issues related to lithium ion battery

　　Author ：Iflowpower – Portable Power Station Supplier

We now use the most used mobile phone inside to install lithium-ion batteries, resulting in six major aspects of the cause of lithium-ion battery explosion: 1. External short-circuit external short circuit may cause improper operation, or misuse, due to external short circuits, The battery discharge current is large, the heat of the battery can cause the diaphragm to shrink or completely damage the diaphragm inside the battery cell, resulting in an internal short circuit, and thus exploding. External short circuit possible labor:²The upper battery is not good, resulting in a positive and negative contact;²The battery is fired during turnover;²The user is short-term short circuit when using;²The protected circuit board has failed.

II. Internal short circuit due to short-circuit phenomena internally, the electrical cell current discharges, there is a large amount of heat, burn the diaphragm, resulting in a larger short circuit, so that the battery will break the electrolyte into a gas, causing the interior When the pressure is too large, when the outer casing of the battery cannot withstand this pressure, the battery will explode. Internal short circuit:²Standing tailor-made burrs; positive and negative poles, small pieces; negative riveting is not flat, there is burr;²Winding; the upper glue position is wrong; high temperature rubber paper enables the negative ear; the bottom gel is not fully enclosed;²The diaphragm paper has a sand eye; the temperature is too high when the temperature is too high;²The pressure is too pressure during flat;²Uncapied short-circuit cell; assembly micro-short battery cells; the laser welding short-circuit battery is not detected; three.

When the charging is overchaired, the lithium of the positive electrode will change the structure of the positive electrode, and the lithium released Excessive is easy to insert into the negative electrode, and it is easy to cause lithium to lithium surface, and when the voltage reaches 4.5 V, the electrolyte will decompose a large amount of gas. It may cause explosion in all kinds.

Overcharged work:²When the precharge is too large; the pre-charger individual point current is too large; the current is set too large when detecting;²Bad capacity is insufficient;²The individual point voltage is large when detecting; the charger voltage is large when the user is used. Four. Over-off.

The moisture content of the moisture can be reacted with electrolyte in the battery, and the gas, charging, can be reacted with the resulting lithium oxide, resulting in a capacity of the battery, easy to make electricity The core is overcharged to generate a gas, the decomposition voltage of the water is low, and it is easy to decompose the generating gas when charging. When this series of generated gas increases the internal pressure of the battery, when the outer casing of the battery cannot be affected, electricity The core will explode. 6.

The negative electrode capacity is insufficient when the negative electrode portion of the positive electrode portion is insufficient, or when there is no capacity, the part or all of the lithium that appears when charging is not inserted into the interlayer structure of the negative electrode graphite, and the surface of the negative electrode, When the protruding delegated crystal is formed, when charging is charged, the protrusions are more likely to cause lithium precipitation. After dozens to hundreds of cycles of circulation, the dendrites will grow up, and finally pierced the diaphragm paper, so that the internal appearance Short circuit. Post-negative pole capacity is insufficient:²The positive electrode has a high capacity; the positive and negative mix is ​​uneven; the positive electrode dressing is large; the positive electrode coating is uneven; the pole tail stack is charged;²The negative electrode is low; negative electrode coating is uneven; negative electrode dark; negative electrode scratches; negative electrode dew foil; negative particles; negative electrode tablets; positive and negative power distribution errors; negative poles Positive pole; battery explosion causes more difficult to understand, everyone does not understand what kind of behavior may lead to battery explosions, and will not realize what behavior is wrong during the charging of mobile phones.

Operation, there will be dangers, the following introduces small details of several lithium-ion batteries, I hope to be able to accurately charge and use mobile phones in accordance with guidance: mobile phone use has extensive into our lives, but there is another type of new energy car, some people Maybe it is doubtful, what is the new energy car? Is it battery? Is the battery safe in the car? Next, a question: 1. What is the new energy car? New energy vehicles refer to all other energy vehicles outside of gasoline, diesel engine. Including fuel power batteries, hybrid vehicles, hydrogen energy motivations and solar cars, etc.

Its exhaust emissions are relatively low. According to incomplete statistics, more than 4 million Liquefied petroleum gas cars in the world, more than 1 million natural gas cars. At present, new energy vehicles selling in my country are mostly hybrid vehicles and pure electric vehicles.

It is important to have the following three types, oil-electric hybrid car pure electric car fuel power battery car drive mode engine + motor drive motor drive motor drive energy system engine, battery battery fuel power battery energy and basic equipment gas station / grid charging equipment grid charging equipment plus Hydrogen equipment emissions low displacement zero volume ultra-low displacement or zero displacement important feature battery long / still partially dependent diesel endless mileage short / initial cost high energy efficiency high / battery long / cost high commercialization process has grown The amount of production is produced, but it is still in the development stage of the R & D stage. Electric cars is currently visible. Have the opportunity to replace the traditional steam, locomotive new means of transportation.

Traditional vehicles' power source is gasoline or diesel engine, except for engine instructors, also have a fuel tank, oil pump, filter, air filter, a chemical oil, a nozzle and an ignition device, and a silencer is equipped with the exhaust pipe. And the water-cooled engine also cools the water system. In contrast, the power system of electric vehicles seems to be simple.

Second. The battery in the new energy vehicle is currently common in the market. The power system is divided into two kinds.

One is the electric vehicle using the battery system. Its important power components are battery packs, chargers, power controllers and motors. Wait, therefore the power system is simpler; there is an electric vehicle with a fuel power battery as a power system.

From the development of new energy vehicles, their power supply is important including lithium-ion batteries, nickel-hydrogen batteries, fuel power batteries, lead-acid batteries, supercapacitors, wherein the lead-acid battery, supercapacitor is mostly in the form of auxiliary power source. Important reason is that these battery technology is not completely mature or disadvantageous. Compared with traditional cars, there is a lot of gaps on the maintenance mileage, which is also an important reason for the development of new energy vehicles.

Since the car should drive a large current, the characteristics of the lithium-ion battery are more suitable, but due to the safety of the lithium ion battery, if the process will have a preheating, there is a problem, so there are also many new products, hope Improved security. At present, the type of battery selected from the mainstream pure electric car type: lithium iron phosphate ion battery is a lithium ion battery using lithium iron phosphate as a positive electrode material. It is characterized by a valuable element such as cobalt, the raw material is low, and phosphorus, iron It is rich in the earth, there will be no feeding problem.

Its theoretical working voltage is moderate (3.2V), the unit weight is large (170mAh / g), high discharge power, can be quickly charged and the cycle life is long, high temperature and high thermal environments. The advantage is that higher security, longer service life, excluding any heavy metals and rare metals (low raw material costs), support fast charging, wide working temperature range.

Disadvantages There are some performance defects, such as the resonance density and the compact density, resulting in low energy density of the battery, high manufacture cost and battery manufacturing cost, low battery finance rate, poor consistent, knowledge, knowledge Property rights, etc. Trimer polymer lithium-ion battery refers to a lithium ion battery of lithium nickel cobalt-manganese acid (Li (Nicomn O2) three-element positive material material. The advantage is that the energy density is high, the cycle performance is good.

At present, the nominal voltage of the battery has reached 3.7V, which has reached or exceeds the lithium cobalt-ion battery level on the capacity. Disadvantages is that the high temperature structure is unstable, resulting in high temperature safety, and the pH is too high to make the monomer, which causes danger, and the current cost is higher.

Third. How to evaluate the safety performance of the battery, I think it can be considered from three aspects. 1.

Will it spontaneously, explode? As for the electric vehicle, why will the battery exploded, or start from raw materials. Lithium iron phosphate ion batteries and three-dimensional ion batteries, both materials will decompose when reaching a certain temperature, different, three-dimensional lithium materials will decompose at a lower 200 degree, and lithium iron phosphate material is About 800 degrees. And the chemical reflection of the three-dimensional lithium material is even more intense, and the oxygen molecule will be released, and the electrolyte is rapidly burned under high temperature use, and the chain reaction occurs, so the three-dimensional lithium material is more likely to fire.

Therefore, some people say that the lithium iron phosphate ion battery is currently the safest electric car battery. 2. Is the high voltage current of the battery safe? In this regard, it is necessary to combine the design of the car, that is, because the car is different.

I have seen an announcement of the trousers, which is said that the high pressure design of this electric car is designed in accordance with Daimler high pressure safety requirements. If so, then we don't have to worry, because the high-pressure safety design requirements of Dally, is Mercedes-Mercedes-Benz, Porsche, BMW, Audi, Volkswagen 5 car companies unanimously recognized. Take these five brands, it is worth trusting.

3. The radiation of the battery is not big? It must be proposed here that our country's demand in electromagnetic standards is very strict, and even some parties are higher than international standards. According to the safety standards of the electromagnetic radiation electromagnetic field, the magnetic field radiation safety standard is 100μT.

Our mobile phone, charger, computer and other electronic products have magnetic fields, the value is in 4μT or so. It's intuitive, and the mobile phone is 0.20 when you watch WeChat.

μT, electromagnetic radiation when sending WeChat is 0.45μT, and the electromagnetic radiation when playing video is as high as 19.00μT.

Electromagnetic radiation of electric cars, I found several sets of measured data on Aika Auto Online: BYD E6 is about 2.95μT; Jianghuai IEV4 pure electric car is about 0.597μT; the highest level of magnetic field in the sprout is about 0.

39μT. Therefore, the electromagnetic radiation safety of electric vehicles can be safe. Which of the electric car batteries is good, there is still a lot of differences in the industry, but it is consistent, that is, there is no battery technology to truly meet all technical requirements of new energy vehicle powered lithium batteries.

But through the comparative analysis of us, it can be seen that the performance of the lithium phosphate ion battery is still more stable and safe. If you want to buy a car according to this, more reference vehicles should be used. Finally, in order to use mobile phones and new energy vehicles in the world, many countries and international organizations in the world have launched a wide range of batteries, automotive safety standards and inspection requirements, including several standards of lithium-ion batteries and new energy vehicles and Detection is:¶锂离子电池标准和检测1)IEC62133Edition1.

0便携式和便携式设备用密封含碱性或其他非酸性电解液二次电芯和电池（Secondarycellsandbatteriescontainingalkalineorothernon-acidelectrolytesSafetyrequirementsforportablesealedsecondarycells，andforbatteriesmadefromthem，foruseinportableapplications）；2）IEC61960Edition1.0便携式设备用含碱性或其他非酸性电解液二次电芯和电池-二次锂离子电芯和电池（Secondarycellsandbatteriescontain-ingalkalineorothernon-acidelectrolytesSecondarylithiumcellsandbatteriesforportableapplica-tions）；3）IEC60950-1Edition1.0信息技术设备的安全（InformationtechnologyequipmentSafetyPart1:Generalrequirements 4) IEC60086-4: 2007 One battery - Part 4: Lithium ion battery safety (PrimaryBatteries–Part4: SafetyOflithiumbatteries); 5) UL1642ED4 Lithiumbatteries; 6) UL2054ED2 Civil and commercial batteries (HouseholdCommercial Batteries); 7) UNST / SG / AC.

10 / 11 / Rev.4-2003 Dangerous Goods Transportation Recommendations - RecommendationSonthetsportofdangeriOdationSmanualOftesandcriteria, FouRensmanualOftests; 8) GB / T18287-2000 "Total Specifications for Lithium Ion Battery for Cellular Telephone"; 9) JISC8714: 2007 Single Battery of Lithium Ion Battery by Lithium ion Battery is the safety test of battery pack; 10) IEEESTD1625-2004 Laptop with Rechargeable Battery (IEEESTD1725-2006 mobile phone) rechargeable battery. At present, various standards of lithium-ion batteries are important from three perspectives to examine the electrical properties and safety performance of lithium-ion batteries: 1) Safety of products; 2) Environmental adaptability; 3) Electrical performance.

Different standards have a focus on the detection of the battery, for example: IEC61960 is important to the electrical performance test of lithium ion batteries; IEC62133 and Japanese JISC8714 require the safety and environmental adaptability of the product; GB / T18287 not only contains some security detection Project also covers performance testing; UL2054 and UL1642 fully examine the battery and battery in various environments, including fault conditions, heavy pressure conditions, and combustion conditions.