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Lithium battery performance testing project
255 2023-08-14
Battery is the main source of power for products, which can drive the operation of equipment. Detailed testing of the battery using testing tools can ensure its safety and prevent spontaneous combustion and explosion caused by excessive temperature. Cars are the main means of transportation for everyone, and the frequency of use is very high. Therefore, in order to ensure the safety of drivers, battery testing is imperative. The testing method is to simulate various accident situations, Judging whether the quality of the battery is qualified, observing whether the battery will explode, and using these tests can effectively avoid risks and maintain stability.
1. Cycle life
The number of cycles of a lithium battery reflects how many times the battery can be repeatedly charged and discharged. According to the different environments in which lithium batteries are used, the cycle life can be tested to determine how much the battery can achieve at low temperature, room temperature, and high temperature. The standard for battery disposal is usually selected based on the purpose of the battery. If the battery is used for power batteries (electric vehicles, electric forklifts), etc., a discharge capacity maintenance rate of 80% is generally chosen as the standard parameter for disposal. However, if the battery is used for energy storage, energy storage, etc., it can be relaxed to 60%. If the discharge capacity/initial discharge capacity of the battery that we often come into contact with is less than 60%, it is no longer necessary to use it and cannot last for half a day.
2. Magnification
Nowadays, lithium batteries are not only used for 3C, but also increasingly used in power batteries. Electric vehicles need to change the current when driving under different operating conditions. In the current fast-paced life, the shortage of electric vehicle charging stations has increasingly high requirements for fast charging of lithium batteries. Therefore, it is necessary to test the rate performance of lithium batteries. Testing can be carried out according to the national standard of power batteries. Currently, both domestic and foreign battery factories are producing special high rate batteries to meet market needs. The design of high rate batteries can be started from the types of active materials, electrode surface density, compaction density, electrode ear selection, welding process, and assembly process. Interested friends can learn about it themselves.
3. Security testing
Safety can be said to be a matter of great concern for battery users, whether it is the explosion of mobile phone batteries or the ignition of electric vehicles, it is enough to make people tremble. The safety of lithium batteries must be inspected, including overcharging, over discharge, short circuit, drop, heating, vibration, squeezing, puncture, etc. However, from the perspective of lithium batteries, these safety tests are passive safety tests, which means placing a battery there and letting foreign objects actively damage the battery to test its safety. When submitting for inspection, it is necessary to design the batteries and modules accordingly for safety testing. However, in actual use, such as electric vehicles losing control and colliding with other vehicles or objects, it is an irregular collision and may face more complex situations. However, in this way, the cost of testing is higher, and only relatively reliable testing content can be selected.
4. Discharge at low temperature, discharge at high temperature
The impact of temperature on the discharge performance of batteries is directly reflected in the discharge capacity and discharge voltage. As the temperature decreases, the internal resistance of the battery increases, the electrochemical reaction speed slows down, and the polarization internal resistance rapidly increases. The discharge capacity and discharge platform of the battery decrease, affecting the output of battery power and energy.
For lithium-ion batteries, the discharge capacity drops sharply at low temperatures, but at high temperatures, the discharge capacity is not lower than room temperature, and sometimes slightly higher than room temperature capacity. The main reason is that the migration rate of lithium ions increases at high temperatures, and lithium electrodes do not decompose or form hydrogen gas at high temperatures, as nickel electrodes and hydrogen storage electrodes do. When the battery module is discharged at low temperature, as the discharge proceeds, heat is generated due to resistance and other reasons, causing the battery temperature to rise, manifested as an increase in voltage. As the discharge proceeds, the voltage gradually decreases.
At present, the batteries on the market are mainly ternary batteries and lithium iron phosphate batteries. Due to the unstable structure collapse of ternary batteries at high temperatures, their safety and safety are much worse than those of lithium iron phosphate batteries. However, their energy density is higher than that of lithium iron phosphate batteries, so the two systems are developing simultaneously.