What is the life of the lithium-ion power battery?

　　Author ：Iflowpower – Постачальник портативних електростанцій

Lithium-ion power lithium battery monomers do not meet the power demand of electric vehicles, so electric vehicles must use multiple batteries to serialize in series, and the power lithium battery pack constructed to supply electric vehicles. From the current level of lithium-ion dynamic lithium battery monomer, various factors in the production process affects the same model of the monomer battery in terms of voltage, capacity, internal resistance, etc. The performance of the power lithium battery pack is determined in the performance of the battery monomer, but it is not a simple accumulation of the performance of the cell.

Due to the presence of inconsistency in the performance of the unit cell, the power lithium battery pack is repeatedly used in the electric vehicle, and various problems in the power lithium battery pack cause the service life shortened. Restricted to the current lithium-ion power lithium battery technology development bottleneck, research on the factors of the life of the dynamic lithium battery, and solve the problem of extending the life of the dynamic lithium battery is very important. This will help the development of lithium ion power lithium batteries in electric vehicles and improve the efficiency of lithium ion powered lithium battery.

The influencing factors of the life of the dynamic lithium battery monomer use the life of the power lithium battery used in the electric vehicle terminal, meaning is 20% of the attenuation of the battery reaches the initial capacity. When the life of the power lithium battery is repeatedly charged on the electric vehicle, it will decline due to the continuous occurrence of the side reaction of the lithium ion battery. This recession occurs in the following aspects: changes in the lattice structure of the electrode material; decomposition, peeling or corrosion causes the reactive material; the decrease in electrolyte decomposing and new impedance; due to the lithium electrode Or sub-reactive causes a delatable lithium ion being consumed; a side reaction generated gas, insoluble matter, and adhesive modification and an impedance caused by the concentrate corrosion increase.

From the actual use environmental conditions, the factors affecting the life of the dynamic lithium battery monomer are important to charge and discharge cut-off voltage, charge and discharge ratio, use temperature, and shelving conditions. There have been many data literatures that in a certain range, the cycle life of different charging cutoff voltage is, the higher the charging voltage, and the shorter. This shows that the charging cutoff voltage on battery life is very large.

High charging cutoff voltage will exacerbate the occurrence of battery side reactions caused by shortening battery life. When the power lithium battery is used on a vehicle, due to the various driving conditions of the electric vehicle, the performance of the battery is prone to recession and the performance of the higher potential region is more severe. Dynamic lithium batteries in the use of electric vehicles to meet different driving and discharge ratins during the use of electric vehicles.

Studies on the dynamic lithium battery magnification charge and discharge show that the magnification charge and discharge will accelerate the decay of the battery capacity, the larger the charge and discharge rate, the faster battery capacity attenuation. This is important because the changes of the structure and properties of the positive electrode material and the thickness of the surface of the negative electrode are caused by the difficulty of diffusion. If the charge and discharge rate is too large, it is possible to cause overheating of a single battery, short circuit caused an explosion.

Different power lithium batteries have different optimal use temperatures, high or too low temperatures affect the battery life. As the temperature is lowered, the discharge capacity of lithium-ion power lithium battery will be reduced. This is because the ion conductivity of the electrolyte decreases as the temperature is lowered, which causes the internal resistance of the battery to increase, resulting in deterioration when the battery is deteriorated at low temperatures.

Dynamic lithium batteries will occur from the nature of the battery itself, and the positive and negative electrode material is passivated, electrolyte decomposition, etc. due to the nature of the battery itself. Experimental results show that the negative electrode SEi performance is unstable to cause rapid decline of negative electrode active materials, and it is prone to lithium metal precipitation, and a lithium ion battery forming a stable SEI film can store more than 4 years under high temperature conditions while different electrolyte components.

Different degrees of recession to electrode materials. The inconsistency of the monomer on the influencing of the power lithium battery pack is an inconsistency in the battery monomer. It has occurred during the manufacturing process.

Due to the thickness of the battery polar plate, the micropore rate, the activation of the active material, etc. The inconsistency on this battery internal structure will make the same number of the same type of battery in the same batch, the voltage, capacity, internal resistance, etc. of the same type of battery, etc.

The inconsistency of the monomer battery on the life of the dynamic lithium battery pack is divided into inconsistencies of voltage, inconsistencies of capacity and inconsistencies of internal resistance. During the grouping of the cell, if the inconsistency of the voltage is large, it will cause the low voltage battery to be used together with the normal battery. Because when there is a low voltage battery in parallel, a charging phenomenon occurs, and other batteries will charge the battery.

This connection can make the capacity of the low-voltage battery have increased significantly and the high voltage battery capacity is reduced, and the energy loss does not meet the ideal external output. The initial capacity is inconsistent in the battery. The screen has been greatly reduced, and although the use process, although the battery cell can be used alone, the initial capacity of the unit cell is different.

However, the continuous charge and discharge process of electric vehicles makes this inconsistency to amplify to some extent, and the capacity is different with the rate of attenuation of the cycle. With the increase in battery cycle, the difference in capacity will become larger. This will make the capacity of the unit cells plus the attenuation to drive the capacity attenuation of the entire battery pack.

The inconsistency of the internal resistance makes the voltage current in the battery pack unevenly distributed, and over-pressure charging or undervoltage discharge is partially. The inconsistency of the internal resistance will make the cells in the discharge in the discharge, the faster the temperature increases, the faster the temperature is increased, and it is possible to finally cause thermal out of control. Various inconsistencies such as voltage, capacity, internal resistance results in differences in battery monomer life and battery pack life, and important performance in temperature difference, charge and discharge ratio difference, discharge depth difference and available capacity difference.

For example, the difference in discharge depth, due to the difference in the initial capacity of the battery, most of the batteries are still in a shallow discharge, and the low capacity battery monomer has been depressed. Summarizing the factors affecting the life of the power lithium battery group, causing the performance of battery packs to have more serious recessions, especially under high temperature and low temperature or over-discharge, and lack effective management and control, battery packs Performance will further decline. In addition, a large number of monomer batteries is connected to parallel to a single single body that is poor in capacity and performance limits the performance of the entire battery pack, which in turn limits the full use of the battery pack.