L822 battery.Summary of technical parameters of lithium iron battery

　　Summary of technical parameters of lithium iron batteries. Lithium-ion battery cells are composed of positive and negative electrodes, electrolytes and separators. In the power lithium battery system, each parameter can characterize the different performance of the system. As an electrochemical power source, the iron lithium battery naturally has characteristic parameters such as voltage, internal resistance, capacity, energy, and power.

　　Technical parameters of lithium iron battery

　　Generally speaking, when we use lithium batteries, we will pay attention to some technical indicators as the main factors to measure the "quality" of its performance. So, which indicators should we pay special attention to when using them? Please read below.

　　1.Capacity

　　The unit of capacity is generally "mAh" or "Ah", and there is a difference between rated capacity and actual capacity when used. Rated capacity refers to the total amount of electricity that a fully charged lithium-ion battery can provide when it is discharged to the cut-off voltage at a specific discharge rate under laboratory conditions. The actual capacity is generally not equal to the rated capacity, and is directly related to temperature, humidity, charge and discharge rate, etc. Under normal circumstances, the actual capacity is smaller than the rated capacity, and sometimes it is even much smaller than the rated capacity. For example, in the winter in the north, if the mobile phone is used outdoors, the battery capacity will drop rapidly.

　　2. Energy density

　　Energy density refers to the amount of electricity that can be stored and released by a battery per unit volume or unit weight. There are two units: Wh/kg and Wh/L, which respectively represent weight specific energy and volume specific energy. The power here is the integral of the capacity (Ah) and the operating voltage (V) mentioned above. In application, the indicator of energy density is more instructive than capacity.

　　The improvement of energy density of lithium-ion batteries is a slow process, far lower than Moore's Law of the integrated circuit industry. This has resulted in a scissor gap between the performance improvement of electronic products and the improvement of battery energy density, which continues to increase over time. expand.

　　3. Charge and discharge rate

　　This indicator will affect the continuous current and peak current of the lithium battery when it is working, and its unit is generally C. By multiplying the current value corresponding to the charge and discharge rate by the operating voltage, the continuous power and peak power indicators of the lithium-ion battery can be obtained.

　　The more detailed the charge and discharge rate index is defined, the greater the guidance significance for use. In particular, lithium-ion batteries, which are used as power sources for electric vehicles, need to specify continuous and pulse rate indicators under different temperature conditions to ensure that lithium-ion batteries are used within a reasonable range.

　　4.Voltage

　　The voltage of lithium battery includes open circuit voltage, working voltage, charging cut-off voltage, discharge cut-off voltage and other parameters.

　　5.Lifespan

　　The life of lithium iron battery is divided into two parameters: cycle life and calendar life. Cycle life is generally expressed in units of times, which represents the number of times a battery can be charged and discharged. Of course, there are conditions here. Generally, under ideal temperature and humidity, deep charge and discharge are performed at the rated charge and discharge current, and the number of cycles experienced when the battery capacity decays to 80% of the rated capacity is calculated.

　　6. Internal resistance

　　Inside the lithium iron battery, lithium ions move from one pole to the other pole. The factors that hinder the movement of ions in the process together form the internal resistance of the lithium battery. Its main parts include the physical internal resistance of conductive parts; the inherent resistance of electrochemical substances such as motor materials, diaphragms and electrolytes; the temporary increase in the obstruction to the movement of lithium ions when there is current inside the battery; these three parts together constitute the internal The subject of resistance.

　　Internal resistance is most sensitive to temperature, and the internal resistance value can change greatly at different temperatures. One of the important reasons for the degradation of lithium battery performance at low temperatures is the excessive internal resistance of the battery at low temperatures.

　　7.Power

　　The power here, to be precise, should be specific power, which is the charge and discharge power capability of a single unit or the charge and discharge power capability of a battery cell per unit mass or unit volume. Whether a lithium battery can perform high-power charging and discharging is already determined when it is designed.

　　8. Battery pack consistency

　　This parameter is quite interesting. Even if the battery cells of the same specifications and models are grouped together, the performance of the battery packs such as voltage, capacity, internal resistance, and lifespan are very different. When used in electric vehicles, the performance indicators often fall short of the standard. to the original level of a single battery.

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