Structure and working principle of lithium iron phosphate batteries

Source: 2020 - 04 - 10 all clicks: lithium iron phosphate battery is the full name of lithium ion batteries, lithium iron phosphate the name was too long, hereinafter referred to as lithium iron phosphate batteries. Because of its performance is particularly suitable for power applications to join in the name of the 'power' is a word, the lithium iron phosphate power battery. Also some people call it 'lithium - Iron ( Life) Power battery '. The working principle of lithium iron phosphate battery refers to the lithium iron phosphate as the anode material of lithium ion batteries. Lithium ion battery cathode material mainly include acid lithium cobalt and lithium manganese acid, lithium nickel acid, ternary material, lithium iron phosphate, etc. Lithium cobalt oxide is most of the lithium ion battery anode materials. Significance in the metal market, the cobalt ( Co) Is the most expensive, storage, nickel, Ni) , manganese, Mn) Relatively cheap, and iron ( Fe) Store more. Anode material price in line with the price of these metals. Therefore, the use of lithium ion battery made of LiFePO4 cathode material should be quite cheap. Its another characteristic is environment protection without pollution to the environment. The requirements of the rechargeable batteries are: high capacity, high output voltage, charge and discharge cycle performance is good, stable output voltage, large current charge and discharge, electrochemical stability, the use of safe, Don't charge, discharge and short circuit caused by improper operation, such as the combustion or explosion) , wide working temperature range, non-toxic or less poison, no pollution to the environment. Using lithium iron phosphate lithium iron phosphate battery anode is good these performance requirements, especially in the large discharge rate discharge ( 5 ~ 10 c discharge) , stable discharge voltage, security, not burning, not explode, and life ( Cycle) , no pollution to the environment, it is the best, is currently the best large current output power battery. Structure and work principle of LiFePO4 as the positive pole of the battery, through the aluminum foil and the positive connection of the battery. Middle is a polymer membrane, it will separate the positive and negative, but lithium ion Li can pass, and electronic e - We don't. On the right is the battery cathode, by carbon ( Graphite) Composition, with copper foil is connected to the cathode of the battery. In the battery is a battery electrolyte between both ends up and down, it was sealed in a metal box. When LiFePO4 battery, the positive lithium ion Li through polymer membranes to negative migration. In the process of discharge, the lithium ions in the cathode through the diaphragm to the positive transfer. Lithium-ion batteries based on lithium ion moves back and forth between charging and discharging of the facts. The main performance of the battery rated voltage is 3. 2 v, terminal charge voltage of 3. 6 v, terminal discharge voltage of 2. 0v。 Because each manufacturer USES the quality of anode, cathode, electrolyte materials and process is different, its performance also has certain difference. For example, the same model ( The same packaging standard cell) The battery capacity difference is very big, 10% ~ 20%) 。 To be sure, different manufacturer production of lithium iron phosphate battery performance parameters vary; In addition, there are some batteries are not included in the performance, such as battery internal resistance, self-discharge rate, temperature of the charge and discharge, etc. Lithium iron phosphate power battery capacity difference is very big, can be divided into three types: small, only a fraction of ma, only a few tens of milliamps of medium, only a few hundred ma. Different types of battery there are some differences in the same parameters. Use STL18650 over discharge to zero voltage test: ( 1100 mah) Lithium iron phosphate power battery do zero voltage discharge test. Test conditions: 0 to 1100 mah STL18650 batteries. To 0 c 5 c, discharge voltage, discharge 1. 0c。 To 0 v battery is divided into two groups: a group of seven days, another group of 30 days. After finishing storage charge 0. 5 c, discharge 1. 0c。 Finally, compares the two kinds of storage cycle zero voltage difference. The test results show that the zero voltage storage after 7 days, without leaking batteries and performance is good, the capacity of 100%. After 30 days, no leakage, good performance, production capacity by 98%; Stored for 30 days later, the battery charge and discharge, three times capacity up to 100%.