Although the cycle life of lithium batteries is much longer than that of lead-acid batteries and nickel-metal hydride batteries, the capacity of lithium batteries will gradually decay during use, so why does the capacity of lithium batteries decay?

　　The capacity degradation of lithium batteries is mainly due to the following reasons:

　　1. Structural changes of cathode materials

　　The positive electrode material will produce induced stress during the long-term charging and discharging process, which will cause the fragmentation of crystal grains and initiate the propagation of cracks, causing mechanical damage to the structure of the material, thereby causing degradation of electrochemical performance.

　　2. Anode material structure

　　The negative electrode material will cause the excessive growth of the SEI film during the long-term charge and discharge process, thereby consuming active lithium, thereby causing irreversible capacity degradation.

　　3. Oxidative decomposition and interface reaction of electrolyte

　　The electrolyte will significantly affect the specific capacity, life, rate charge and discharge performance, operating temperature range and safety performance of lithium-ion batteries. With the recycling of lithium batteries, the gradual decomposition of the electrolyte will cause the attenuation of the battery capacity.

　　4. Positive overcharge reaction

　　When the ratio of the positive electrode active material to the negative electrode active material is too low, the positive electrode is likely to be overcharged. This will disrupt the capacity balance between the electrodes, resulting in a loss of battery capacity and irreversible.

　　5. Electrode instability

　　The instability of the active material of the positive electrode during charging will cause the capacity to decrease by reacting with the electrolyte.

　　From the analysis of the above factors, it can be seen that the important factor affecting the capacity decay of lithium batteries is the structural stability of the positive electrode material.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect replacement for lead-acid batteries, and they are the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.