What is the quality of lithium ion batteries?

Whether the performance of lithium ion batteries is good or not is mainly related to the electrochemical performance of lithium ion batteries; the electrochemical performance parameters of lithium ion batteries mainly include the following five aspects. Rated voltage: The rated voltage of commercial lithium-ion batteries is generally 3.6V (some 4.2V lithium-ion battery products are also appearing on the market, but the proportion is not large), and the working voltage range is 4.1~2.4V. The lower limit termination voltage is set to other values, such as 3.1V. Rated capacity: refers to the capacity obtained when discharged to the final voltage at a constant current of 0.2C. 1C capacity: refers to the capacity obtained by discharging at 1C constant current to the final voltage. The 1C capacity is generally smaller than the rated capacity, and the smaller the difference, the better the current characteristics of the battery and the stronger the load capacity. High and low temperature performance: The high temperature of lithium ion battery can reach +55℃, and the low temperature can reach -20℃. In this ambient temperature range, the battery capacity can reach more than 70% of the rated capacity. Especially in a high temperature environment, there are few effects on battery performance. Charge retention capacity: The battery is left open for 28 days after being fully charged, and then discharged according to the percentage of the ratio of the capacity obtained by 0.2C discharge to the rated capacity. The larger the value, the stronger the charge retention capacity and the smaller the self-discharge. Generally, the charge retention capacity of lithium-ion batteries is above 85%. Cycle life: As the lithium-ion battery is charged and discharged, when the battery capacity is reduced to 70% of the rated capacity, the number of charge and discharge times obtained is called the cycle life. The cycle life of lithium-ion batteries is generally required to be greater than 500 times. 1 Basic requirements for cathode materials A cathode material that can be widely used must meet the following requirements. First, the material itself has a high potential, so that a large potential difference can be formed between the material and the negative electrode material, resulting in a battery design with high energy density; at the same time, the insertion and extraction of charged ions has little effect on the electrode potential, and the charging and discharging process will not Excessive voltage fluctuations will not adversely affect other electrical systems in the system. Second, the material contains a high amount of lithium ions and the intercalation and deintercalation of lithium is reversible. This is a prerequisite for high capacity. Some cathode materials have a high theoretical capacity, but half of the lithium loses its activity after the first intercalation. Such materials cannot be put into commercial use. Third, the lithium diffusion coefficient is large, the lithium moves more quickly inside the material, and the ability to intercalate and deintercalate is strong. It is a factor that affects the internal resistance of the cell and also a factor that affects the power characteristics. Fourth, the material has a large specific surface area and a large number of lithium ion insertion sites. The surface area is large and the intercalation channel of lithium is relatively short, which makes it easier to intercalate and deintercalate. While the channel is shallow, the position for inserting lithium ions should be sufficient. Fifth, it has good compatibility and thermal stability with the electrolyte, which is due to safety considerations. The positive electrode material does not easily react with the electrolyte, and is still structurally stable at higher temperatures and still does not easily react with the electrolyte. Such a material will not supply heat for the extra heat accumulation of the battery cell, and can reduce the probability of the battery cell entering the self-heating stage. Sixth, the materials are easily available and the production performance is good. Low cost, easy production of materials into electrodes, and stable electrode structure are favorable conditions for the popularization and application of materials. 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 post: What are the factors that cause the capacity of lithium-ion battery to plunge at the end of its life?