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Analysis the cause of the lithium ion battery ballooning and explosion

by:Vglory      2020-08-15
Lithium ion battery: a secondary battery ( Rechargeable batteries) , it mainly rely on lithium ions move between the positive and negative to work. In the process of charging and discharging, Li + embedded back and forth between the two electrodes and embedded off: when charging, Li + embedded from the anode, after anode, electrolyte embedded in the cathode in the rich lithium state; Discharge is the opposite. Lithium ion batteries, the anode of lithium atom lose electrons, oxidation for lithium ion. Lithium ions via the electrolyte to the anode, into the cathode storage, and access to an electron, reduction of lithium atom. Discharge, the whole program upside down. In order to prevent negative direct touch and short circuit, the batteries are inside the battery will be combined with a diaphragm paper have many pores, to prevent short circuit. Good diaphragm paper can also be at high temperature, the battery automatically closed pores, let lithium-ion impenetrable, prevent danger happening. Lithium batteries work principle diagram is illustrated below: lithium-ion battery ballooning and explosion reasons: 1, the improper use of lithium ion batteries, lithium ion battery charging voltage is higher than 4 a. After 2 v, lithium ion battery voltage is higher than 4. After 2 v, the anode material in less than half the number of lithium atoms left, store usually break down at this time, let the battery capacity to produce permanent decline. If continue to charge, due to the storage of the cathode has been full of lithium atoms, subsequent anode materials of lithium metal accumulation in the surface. These lithium atoms from lithium ion to the cathode surface to grow in the direction of the dendritic crystal. The lithium metal crystal through the diaphragm paper makes is negative short circuit. Sometimes in short circuit batteries before the first explosion, this is because in the process of overcharge, electrolyte materials can produce gas cracking, such as making the battery shell or blow up pressure valve is broken, and let oxygen in and accumulation in the lithium atoms on the surface of the cathode reaction, then exploded. Therefore, lithium ion batteries, be sure to set the upper limit of voltage, can simultaneously to the battery life, capacity, and security. The most ideal charging voltage upper limit of 4. 2V。 B, lithium batteries discharge voltage will be lower limit. When the batteries voltage is less than 2. 4 v, part of the material will begin to be destroyed. And because the battery self-discharge, put the more the longer the voltage is low, therefore, discharge when had better not in 2. 4 v. Lithium batteries from 3. Discharge to 2 0 v. 4 v during this period, the release of energy accounted for only about 3% of the battery capacity. Therefore, 3. 0 v is as an ideal discharge voltage. C, the current limit has its necessity. When the current is too large, lithium ion battery can not afford time to enter the store, would gather in the material surface. After these lithium ion for electronic, can produce lithium atoms in the material surface crystallization, this has to do with the overcharge, will cause the risk. One thousand battery shell is broken, and would explode. 2, pole piece water react with the electrolyte to generate gas 3, electrolyte itself the quality problem of the 4 internal micro short circuit, battery 5, shell defect etc. Therefore, the protection of lithium ion batteries, to include at least: charging voltage upper limit, lower limit discharge voltage, and current limit. Generally lithium battery pack, in addition to the lithium battery core, there will be a piece of protection board, the protection board is mainly to provide all three. Protection board, however, these three protection is obviously not enough, lithium battery explosion or disengaged from around the world. To ensure the safety of the battery system, the battery must be the cause of the explosion, a more careful analysis. More related data refer to 'the advantages of lithium electric car emergency power'
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