The reasons for the capacity attenuation of lithium batteries are as follows: 1. Lithium battery abuse: When the SOC of lithium batteries is less than 120%, there is no loss of capacity. obvious ability. When SOC is above 120%. Lithium deposition begins to occur on the negative electrode, and due to the formation of a thicker SEI film, the impedance increases and causes the loss of active lithium. If overcharging continues, it will cause thermal runaway of the lithium battery. the decomposition rate of the electrolyte will become faster, forming a thick deposit layer on the negative graphite electrode. The lithium contained in this deposited layer will precipitate. High rate charging and discharging will also cause the lithium battery to lose capacity, due to volume. positive and negative electrodes will shrink and expand during the charging and discharging process. Morethe charging and discharging current is larger, the larger the shrinkage and expansion, as well as the stress, the particles of the positive and negative electrodes are more susceptible. break or detach from the current collector during rapid volume changes, resulting in accelerated cycle decay. 2. Temperature factor: It is worth mentioning that the environment and usage conditions of lithium batteries damage their capacity. Temperature is certainly one of the key factors affecting the lifespan of lithium batteries. Too high or too low temperatures will cause the formation of active lithium ions. a decrease in content will destroy the structure of the electrode material and dissolve the metal ions, resulting in significant attenuation of capacitance. The operating temperature of conventional lithium batteries is between -20°C and 60°C. Generally, peLithium battery performance decreases. decreases when it is below 0℃, and the discharge capacity will decrease accordingly, so the working temperature of lithium battery with full performance is generally 0-40℃. The lithium battery temperature required by some special environments is different, and some can even work normally in hundreds of degrees Celsius environment. 3. The main factors that affect the capacity attenuation of lithium batteries are structural damage or inactivation of positive and negative electrode materials, electrolyte decomposition, lithium battery abuse, etc. The process of charging and discharging the battery is a complex electrochemical process, and the factors leading to the attenuation of battery capacity are not the same, and the deterioration of one aspect may trigger otherres factors that jointly affect battery capacity, cycle performance, energy density, etc.
Charging the lithium iron phosphate battery with SOC less than 20 will not damage the battery.
In general, it is best to charge when there is less than a third of the battery remaining. Lithium batteries have no memory effect and can be charged at any time and can be stopped at any time. However, according to statistical findings, charging to 30% to 40% of the remaining power can maximize the life of the lithium battery. A single charge time for an electric vehicle takes approximately 5 to 10 hours. When the charging light changes from red to green, it means the battery is fully charged. At that time, if time permits, it is best to continue charging (floating charge) for about 1-1.5 hours so that the battery can get. more energy.