Lithium ion battery
Time： 2019-06-11 11:53:00
Late in the night of May 26, a Nissan GT-R hit a BYD E6 taxi at high speed on the streets of Shenzhen until it lost control, rotated and caught fire. The ignition site is where BYD E6 lithium-ion batteries are installed. Since then, the safety of lithium-ion batteries has been questioned. There is such a phenomenon in society that "the wall falls down and everyone pushes it down", just like a health expert once, who started with many stars holding the moon, was investigated and punished and then vomited by the whole people, most of whom do not know Chinese medicine at all. Similarly, many people do not understand the structure and principle of lithium-ion batteries at all, so such doubts can only be called "spray". Do you know what a lithium-ion battery is?
First of all, to correct a statement, many people think that lithium-ion batteries are short for lithium-ion batteries. In fact, this is a misunderstanding. The real identity of lithium batteries is primary batteries (non-rechargeable batteries) with lithium metal as the negative pole. Its life can be traced back to Edison. However, lithium batteries are no longer widely used because of their active chemical characteristics and easy combustion and explosion. Later, graphite was used as the negative electrode and lithium-containing compounds as the positive electrode. There was no lithium metal, which effectively avoided the danger caused by too active lithium metal. This is lithium-ion battery. When the battery is charged, lithium ions are generated on the positive electrode, and the lithium ions are moved into the micropore of the carbon material through the electrolyte. The more lithium ions are embedded, the higher the charging capacity. Similarly, when the battery is discharged (that is, the process of using the battery), the lithium ions embedded in the carbon layer of the negative electrode are removed, and then the lithium ions are moved back to the positive electrode and back to the positive electrode. The lithium-ion batteries with more ions and higher discharge capacity can be divided into liquid lithium-ion batteries and polymer lithium-ion batteries according to different electrolytes. The two positive and negative electrode materials of lithium ion batteries are the same. The difference is that the electrolyte of liquid lithium-ion battery is lithium salt + carbonate, and the electrolyte of polymer battery is solid polymer or gel polymer. Because of the difficulty and high cost of polymer purification, it is generally used in small batteries, such as mobile phones and notebook batteries. Most of the power batteries in electric vehicles are liquid lithium-ion batteries. Modern Blue On electric vehicles have used high-energy polymer lithium-ion batteries with a capacity of 16.4 kWh. Polymer lithium-ion batteries are a new generation of high specific energy batteries based on liquid lithium-ion batteries. Polymer lithium-ion battery has the advantages of smaller volume, lighter weight, wider working range and longer life, while it has the same capacity as liquid lithium-ion battery. More importantly, its electrolyte is solid or gel, and there is no danger of leakage of liquid battery electrolyte.