I learned that these parameters have got the key of the ‘power lithium battery’.

I learned that these parameters have got the key of the 'power lithium battery'.

As a post-entry, you will share the performance parameters of the power lithium battery. Although these parameters are more sub-atriosis, they are the most basic elements of the power lithium battery, just like a key, through them to evaluate The powerful lithium battery can open this door. Energy (WH / LWH / KG) unit volume or unit quality battery release energy.

If the volume of the unit, that is, the volume energy density (WH / L), many places are directly referred to as energy density; if it is the quality of the unit, it is the mass energy density (WH / kg), and many places are also called energy.. Such as a lithium ion battery weighs 300g, the rated voltage is 3.

7V, the capacity is 10ah, and it is 123Wh / kg than energy.. According to the “Energy Saving and New Energy Automobile Technology Road Map” announced in 16 years, we can probably have a concept of dynamic lithium battery development.

Down below, by 2020, pure electric car battery monomer is 350Wh than energy KG power density (W / LW / kg) divides energy by time, get power, unit is W or KW. The same truth, the power density refers to the power of the unit quality (some places, directly called the power) or the unit volume battery output, and the unit is W / kg or W / L. The specific power is an important indicator for evaluating whether the battery meets the acceleration performance of electric vehicles.

. What is the difference between energy and power? Examples of the image: the powerful power lithium battery is like the turtle in the turtle rabbit, good endurance, can work for a long time, to ensure the long-term maintenance mileage. The powerful power lithium battery is like a rabbit running in the turtle and the rabbit, which is fast, which can supply high instantaneous current to ensure that the car accelerates well.

. The battery discharge rate (C) discharge ratio refers to the current value of the rated capacity (q) in the regulation, which is equal to the number of battery rated capacity at the value..

That is: charge and discharge current (a) / rated capacity (AH), the unit is generally c-rate, such as from 0.5c, 1c, 5c, etc., with respect to the capacity of 24AH battery: 48a Discharge, its discharge magnification is 2C, in turn, 2C discharge, discharge current is 48A, 0.

5 hours discharge; charged with 12A, its charging magnification is 0.5c, in turn, 0.5C charging, charging current is 12A, 2 The hour is charged; the charge and discharge rate of the battery determines how fast we can store a certain amount of energy into the battery, or release the energy in the battery in the battery.

. The state of charge (%) SOC, full name is StateOfcharge, charged state, also called the remaining battery, the ratio of the capacity of the remaining capacity and its fully charged state after the battery discharge. The value ranges from 0 to 1, when SOC = 0 indicates that the battery discharge is complete, when SOC = 1 indicates that the battery is completely full.

Battery Management System (BMS) is an important way to ensure battery efficient work, so it is the core of battery management.. At present, SOC estimates important open circuit voltage law, safety measures, artificial neural network law, Kalman filtering method, etc.

, we will explain in detail later.. The internal resistance internal resistance means that the battery is currently affected by the battery inside the battery.

. Including ohm internal resistance and polarization internal resistance, where: ohm internal resistance includes electrode materials, electrolytes, diaphragm resistors, and resistance of part parts; polarized internal resistance including electrode resistance and concentration resistance. Specasing with data, the following figure shows a battery discharge curve, the X axis represents the amount of discharge, the Y-axis represents the battery opening voltage, the battery is ideally discharged to the black curve, the red curve is a true state of the battery during the battery.

Illustration: qmax is the maximum chemical capacity of the battery; QUSE is the actual capacity of the battery; RBAT represents the internal resistance of the battery; EDV is the discharge termination voltage; i is a discharge current. As can be seen from the figure, the actual capacity of the battery QUSE

We can also see that the actual capacity QUSE of the battery depends on two factors: how much is the product of discharge current I and battery internal resistance RBAT, and how much is the discharge termination voltage EDV. It should be pointed out that the battery internal resistance RBAT will gradually increase with the use of the battery..

The unit of internal resistance is generally milliom (MΩ), the internal resistance battery, when charge and discharge, the internal power consumption is large, and the heat is severe, which causes the speed of accelerated aging and life attenuation, and will limit the high rate Discharge application. Therefore, the smaller the internal resistance, the better the battery life and the magnification performance..

Usually the measurement method of the internal resistance has an AC and DC Test. Self-discharge battery self-discharge refers to the phenomenon of voltage drop during the opening of the station, also known as the charge capacity of the battery..

In general, the battery self-discharge is important for manufacturing process, material, storage conditions.. Self-discharge can be reversible according to capacity loss: capacity loss can be reversible, and it means that the capacity of the re-charging process can be recovered; capacity loss is irreversible, indicating that capacity cannot be recovered.

At present, there are many research theories for battery self-discharge, summarizing the physical reasons (storage environment, manufacturing process, materials, etc.) and chemical causes (electrodes in electrolyte instability, internal chemical reaction, active substances are consumed Wait), battery self-discharge will directly reduce battery capacity and storage performance. Life battery life is divided into two parameters of cycle life and calendar life.

The cycle life refers to the number of times the battery can circulate and discharge.. That is, at the ideal temperature and humidity, the number of cycles experienced by the rated charge and discharge current, calculating the number of cycles experienced when the battery capacity is attenuated to 80%.

. The calendar life refers to a time span of a battery life (capacity attenuation to 80%) under the use of environmental conditions..

Calendar life and specific use requirements are closely combined, usually specify specific use conditions, environmental conditions, storage intervals, etc.. The cycle life is a theoretical parameter, and the calendar life is more practical.

. However, the calculation of the calendar life is complicated, and the time is long, so the general battery manufacturer only gives the data of the cycle life..

The above picture shows the charge and discharge characteristics of the one-three lithium-ion battery. It can be seen that different charge and discharge methods have different effects on the life of the battery, such as the above figure data, the life of charge and discharge by 25% -75% can reach 2500 times. , That is, the battery we say is shallow and light.

Battery life This topic we will discuss in the future. The consistency of the battery pack is more interesting. Performance indicators often fail to achieve the original level of a monomer battery.

Currently reasonable explanation: After manufacturing, due to the problem of process, the internal structure and material are not completely consistent, itself has a certain performance difference.. The initial inconsistency has accumulated as the battery continues during the use of the charge and discharge cycle, plus the use environment within the battery pack is not the same, resulting in a greater difference in the state of each unit cell.

From the process of use, it is gradually enlarged, so that certain monomer battery performance accelerates in some cases, and eventually triggers battery pack premature failure.. It should be pointed out that the performance of the power lithium battery pack is determined in the performance of the battery cell, but is not a simple accumulation of the performance of the cell.

. Due to the presence of inconsistencies in the performance of the cell, the power lithium battery pack is repeatedly used in the electric vehicle, and the life is shortened..

In addition to requiring the process and to maintain the consistency of the unit cells during the production and or grouping process, the current industry generally uses a battery management system with equalization function to control the consistency of the battery in the battery pack to extend the product. Service life. Chemically, we talk about the last parameter, this parameter is important and the battery manufacturing process is related.

After the battery is made, the cell is charged, and the internal positive and negative electrode is activated, and a layer of passivation layer -Sei (SolidelectrolyteterFace) film is formed on the surface of the negative electrode, making the battery performance more stable, the battery is chemically In order to reflect its true performance, this process is called. The sorting process in the process can improve the consistency of the battery pack, so that the performance of the final battery pack is improved, and the capacity is an important indicator of filtering qualified batteries..

The picture below shows the SEI film, like a black rose like a black. Summary We pass the article, basically summarize all the performance parameters related to the power lithium battery, I hope to help everyone, will not be a “door” when talking about the battery.

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