The three major characteristics of lithium ion battery analysis

A testing battery, battery capacity characteristics of capacity under the different ratio of discharge voltage and capacity curve is shown in figure 1. Figure 1 under different ratio of discharge voltage and capacity of the curve can be seen from the diagram, in the whole course of the discharge of lithium ion battery voltage curve can be divided into three stages: 1) Battery voltage of rapid decline in the initial stage, the discharge rate, the greater the voltage drop in the faster; 2) Battery voltage into a slow change of phase, this paragraph of time is called a battery of platform area, the smaller the discharge rate, the platform area, the longer the duration of platform and the higher the voltage, voltage drop, the more slowly. In the process of actual use of lithium ion battery, hope the battery work as much as possible in the platform area; 3) In battery close when it finished, battery load voltage start fell sharply until discharge cut-off voltage is reached. In the aftermath of the capacity test, at the same time also can get the curve of the discharge current and the capacity of the relationship, as shown in figure 2. Figure 2 different discharge current and the capacity of relation curve can be seen from the graph, the size of the battery discharge current, will directly affect the actual capacity of the battery. Discharge current, the greater the battery capacity decreases, this suggests that the larger the discharge current, the shorter the time of arrival in termination voltage experience. So when it comes to battery capacity, shall indicate the discharge current ( Discharge rate) 。 Second, the battery open circuit voltage characteristic open circuit voltage test [6] for lithium ion battery open circuit voltage and the curve of the battery SOC is shown in figure 3. Figure 3 OCV - battery charging and discharging SOC curve can be seen from the diagram, battery OCV - curve and SOC battery discharge voltage curve trend is basically the same. In the middle of the SOC interval ( 20％＜SOC＜80％） , battery OCV change is very small, battery table area; And in the ends of the interval (SOC SOC < 10% and SOC > 90%) , OCV variation is larger, the lithium iron phosphate battery OCV - SOC curve of the middle area flat, the appearance of the steep on both ends of the head to tail, open circuit voltage method is the use of this stable corresponding relation between SOC estimation. Lithium ion battery OCV - SOC relation curve affected by temperature, discharge ratio, aging degree of smaller [7], but in the condition of charging and discharging two, there are certain differences between the two characteristic curve. Three, battery internal resistance characteristic figure 4 said the lithium iron phosphate batteries during charging and discharging the ohm internal resistance. Figure 4 battery internal resistance curve of lithium iron phosphate battery ohm resistance curve presents the following characteristics: in a broad SOC is surrounded in figure 6, the SOC = 100% [10%] range, battery ohm resistance change is small, and in the lower SOC interval, with the decrease of SOC ohm resistance was substantial, this is because the battery discharge end of the battery internal chemical activity; Within the scope of the whole SOC, charging ohm internal resistance is greater than the discharge ohm internal resistance, this is because the lithium ion battery discharge belongs to the spontaneous reaction, more easily; Charge is by an external power supply, make the embedded lithium ion cathode, more difficult. To be sure, battery internal resistance change is very complex, affected by temperature, depth of discharge, charge and discharge rate, cycles and other factors. The same type of different monomer battery, and battery factory different related inconsistencies and working environment. Lithium battery, USES the domestic and international first-line brand batteries, power strong, long cycle life more. Telephone: details please consult the online customer service, counseling.