Analysis on the factors affecting the safety of lithium-ion batteries

Factors affecting the safety of lithium-ion batteries 1) Internal factors The electrode materials and electrolytes in lithium-ion batteries are flammable. When heated (internal or external), it will cause fires and decompose to produce gas, and a new battery explosion The possibility. At present, the strength of the polymer isolation film is relatively low, and it is easy to damage the film in the event of collision or overheating, resulting in a short circuit of the battery. At the same time, manufacturing process defects can easily cause safety issues for lithium-ion batteries. For example, battery tabs are too long and contact the plates or shells to cause a short circuit; tabs compress the coil core and cause a short circuit between the positive and negative electrodes; metal powder, copper foil, and aluminum foil fragments left between the two poles may perforate the diaphragm and cause a micro short circuit. Wait for a series of questions. 2) External factors that affect the safety of lithium-ion batteries are more complicated. For example, overcharging, external short circuits, severe shocks, etc. may cause spontaneous combustion of lithium-ion batteries. Precautions for use (discharge) Regarding the battery, normal use is the process of discharging. Pay attention to the following points when discharging lithium-ion batteries: First, the discharge current should not be too large, otherwise it will cause permanent damage due to the internal heat of the battery. On mobile phones, this is no problem and cannot be considered. It can be seen from the figure on the right that the larger the discharge current of the battery, the smaller the discharge capacity and the faster the voltage drop. Second, don't over-discharge! The internal electric energy storage of lithium-ion batteries is achieved through electrochemical reversible chemical changes. Excessive emissions can lead to an irreversible reaction of this chemical change. Therefore, lithium-ion batteries are most afraid of over-discharge. Fortunately, a protection circuit has been installed inside the mobile phone battery. The voltage is not low enough to damage the battery. The protection circuit will function and stop discharging. Lithium ion battery: A secondary battery (rechargeable battery) that works by moving lithium ions between the positive and negative electrodes. During charging and discharging, Li+ intercalates and deintercalates back and forth between the two electrodes. When charging, Li+ is released from the positive electrode and inserted into the negative electrode through the electrolyte. The negative electrode is in a lithium-rich state. When unloading, the situation is just the opposite. Lithium-ion batteries are divided into lithium-ion batteries and lithium-ion batteries. Both mobile phones and laptops use lithium-ion batteries. Batteries generally use lithium-containing materials as electrodes, which are representative of modern high-performance batteries. Real lithium-ion batteries are very dangerous and are rarely used in everyday electronic products. Lithium-ion batteries were originally developed by Sony Corporation of Japan in 1990. It inserts lithium ions into carbon (petroleum coke and graphite) to form a negative electrode (lithium or lithium alloy used in traditional lithium-ion batteries). Commonly used cathode materials are LixCoO2, LixNiO2, LixMnO4, LiPF6 + divinyl carbonate (EC) + dimethyl carbonate (DMC). Petroleum coke and graphite are cathode materials, which are non-toxic and rich in resources. The lithium ion embedded in the carbon overcomes the high activity of lithium and solves the safety problem of traditional lithium ion batteries. The positive electrode LixCoO2 of the present invention has reached a higher level in terms of charging and discharging performance and life, and the cost is reduced. Lithium-ion batteries will have a large market in the 21st century. LiCoO2+Cu003dli1-xcoo2+LixC[1] Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.