Analyze the safety hazards of the battery

With the widespread use of batteries, we will come into contact with batteries during the day and at work, but the safety of batteries has become the most worrying issue. In order to ensure the safety of users and allow people to use batteries correctly, the Quality Supervision Bureau conducted a special inquiry. The results showed that the national lithium qualification rate is only 60%! It can be seen that the safety function of the battery still has certain risks! The positive data of lithium batteries is usually composed of lithium The negative electrode is composed of carbon with a special molecular structure. An important component of commonly used positive electrode data is LiCoO2. When charging, the electric potential on the pole forces the compound in the positive electrode to release lithium ions, and the negative electrode molecules are embedded in the carbon and arranged in a sheet-like structure. During discharge, lithium ions are separated from the layered carbon and recombine with the positively charged compound. Electric current occurs in the movement of lithium ions. Although the principle of the chemical reaction is very simple, in actual industrial processing, there are many practical issues to consider: for example, the data of the positive electrode requires additives to insist on repeated charging activities, and the data of the negative electrode must be planned to contain more lithium ions at the molecular structure level. The electrolyte between the positive and negative electrodes must not only be stable, but also have good conductivity to reduce the internal resistance of the battery. In order to prevent the internal active material from directly contacting the outside world, the battery casing should contain all the internal structure, which is generally made of nickel-plated steel plate. In addition, it is also connected to the negative electrode to serve as a negative electrode collector. Generally, there is a ceramic or plastic package on the outside of the casing, and then a label is affixed on the outside of the battery to identify the type and model of the battery and other information. The quality of the casing is very important. If it is too thin to maintain its use, it can easily be broken by the pressure inside (it bursts); if it is too thick, it will lose its elasticity. If it is subjected to external pressure (such as a mobile phone falling), it will cause permanent deformation and increase internal pressure and resistance. If there is a problem with the coating, a short circuit and a lot of heat will also be formed. Inappropriate temperature can cause unwanted compounds in other chemical reactions in lithium batteries, so many lithium batteries have maintenance temperature control gaps or electrolyte additives between the positive and negative electrodes. When the battery is heated to a certain degree, the pores of the composite membrane are closed or the electrolyte is denatured. The internal resistance of the battery is added until the circuit is disconnected. Perhaps the gap between the dielectrics will cause excessive resistance or short circuits. The lithium reaction is carried out on two boards. If the plan is not in place, crystallization will occur, and more and more crystallization and chemical reactions will occur. Once it passes through the insulation layer, a short-circuit large current will occur, a sudden high temperature, and then burst. Generally planning lithium batteries will consider this situation. There is a safety circuit in the battery, which generally uses PTC (current sensitive semiconductor), and the current is too large when maintaining the battery. However, a faulty repair circuit may exacerbate this problem. A key component of the battery is the safety valve. Because the battery is hermetically sealed, some gas will be generated during the reaction of lithium ions and the evaporation of the electrolyte. Once there is gas, the internal pressure will increase, just like a pressure cooker. A normal mobile phone battery has a safety valve, which can safely discharge under high pressure to prevent vicious battery explosion, but if the safety valve plan is not suitable, or the bottom of the safety valve is not installed, the degree of risk can be imagined. The second charger is also a very important choice. The high-quality charger feedback circuit uses a constant current limit. Currently, a uniform maintenance voltage is used. When the voltage is 4.2V, there is no voltage difference between the battery and the charger, and there is no energy exchange. To each other, the battery was not damaged. On the contrary, incomplete chargers do not have a feedback circuit. Excessive charging time will cause the input energy to exceed the capacity of the battery, causing heat to burn and even explode. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: How to charge a new battery? New battery maintenance tips