Inner Mongolia Sanxin Technology Development Co., Ltd
Inner Mongolia Sanxin Technology Development Co., Ltd
In order to create a hardworking corporate culture and improve employee cohesion and hardship, the company conducted a workforce activity for all employees in February 2014.February 22, 2014 The company conducted military training summary awards ceremony.
With the development of technology and technology mature, lithium-ion battery applications more and more widely. Lithium-ion battery with a single high voltage, relatively light weight, environmentally friendly, etc., but after a number of cycles after the charge and discharge cycle will appear the performance of the battery capacity decline. The same conditions, the faster the battery capacity attenuation, the battery quality is relatively poor. Lithium-ion battery cycle performance is an important measure of its quality indicators, many of the lithium-ion battery standards have a cycle of life of this project. Lithium-ion battery charge and discharge cycle process is a complex physical and chemical reaction process, the cycle life of the factors that are multifaceted. On the one hand with the characteristics of the battery itself, such as design, manufacturing process and material degradation, etc .; on the other hand with the use of the battery during the impact of the outside world, such as the use of the environment and charge and discharge system. The following factors affect the cycle of lithium-ion battery life factor analysis. 1 lithium ion battery structure and principle Lithium-ion battery is mainly composed of positive and negative materials, electrolyte, diaphragm, current collector and battery shell, positive and negative materials from two different lithium ion embedded compounds. Charging, lithium ions from the cathode off the sub-through the electrolyte through the diaphragm embedded in the negative, the discharge is the opposite. In the lithium ion battery for the first charge and discharge process, the negative electrode and electrolyte interface to form a layer of passivation film. It is between the electrode and the electrolyte play a role in the diaphragm, the electronic insulator is a good conductor of lithium ions, lithium ions can pass through the passivation layer free to insert and release, with a solid electrolyte characteristics, so this layer of passivation film Known as the "solid electrolyte interface" (solid electrolyte interface), referred to as SEI film [1]. 2 design and manufacturing process In the battery design process, the choice of material is the most important factor. Different performance characteristics of different materials, the performance of the battery is also a gap. Positive and negative material matching cycle performance is good, the battery cycle life will be long. In the ingredients, we should pay attention to positive and negative material added. In general, the design of the assembly process generally requires that the negative capacity of the cathode is relatively excessive, if not excessive, during the charging process will precipitate lithium, the formation of lithium dendrite and thus affect the safety. The anode is too much relative to the positive too much, the positive electrode may be excessive lithium, resulting in structural collapse. Electrolyte in the battery reversible capacity is also a very important factor. Electrode material off, the process of intercalation of lithium ions is always the process of interaction with the electrolyte, this interaction on the electrode material interface conditions and internal structure changes have an important impact [3]. In the process of interaction with the positive and negative materials, the electrolyte will be lost, and in the battery into the SEI film and pre-charge, it will consume part of the electrolyte, so the type of electrolyte and injection volume also affect the battery life. Lithium-ion battery manufacturing process mainly includes: positive and negative ingredients, coating, production, winding, into the shell, injection, sealing, chemical and so on. In the battery production process, the process for each step are very strict. Any process that is not well controlled can affect battery cycle performance. In the process of positive and negative ingredients, should pay attention to the amount of binder, stirring speed, slurry concentration, temperature and humidity, and to ensure that the material can be dispersed evenly. In the coating process, in the premise of ensuring high battery specific energy, reasonable control of positive (negative) coating, the appropriate reduction in electrode thickness is conducive to reducing the battery decay rate [4]. After the coating of the pole piece but also with the roller press further compaction, the appropriate positive compaction density can increase the battery discharge capacity, reduce the resistance, reduce the polarization loss, extend the battery cycle life. When winding, roll into the batteries should be close, not loose [5]. The diaphragm and the positive and negative pole volume is tight, the smaller the internal resistance, but the volume is too tight will cause the pole piece and diaphragm wet difficult, resulting in smaller discharge capacity; roll too loose will make the pole in the charge and discharge process over-expansion , Increased resistance, reduced capacity, shortened cycle life. 3 battery material aging recession Lithium-ion battery charge and discharge cycle is the process of lithium ions through the electrolyte in the positive and negative material back and forth between the de-embedded, moving the process. In the lithium-ion battery cycle, in addition to positive and negative redox reaction occurs, there are a lot of side effects. If the side effects of lithium-ion batteries can be reduced to a low level, so that lithium ions through the electrolyte can always smoothly between the positive and negative materials, can make lithium-ion battery cycle life can be increased. Lithium ions from the positive electrode to the negative must be covered in the carbon anode on the SEI film, SEI film directly affects the battery life cycle. Foreign scholars on the aging of the battery material research earlier, especially on the SEI film research more in-depth. The main research method is through the battery life test data combined with electrochemical characterization means to analyze the battery material stability and recession mechanism [6]. The stability of the SEI film has an important effect on the stability of the battery. SEI film is unstable and easy to precipitate lithium metal, will lead to rapid degradation of the anode active material to form a stable SEI membrane lithium battery can be stored under high temperature conditions for more than 4 years [7]. D. Aurbach et al [8] after the dismantling of the lithium cobalt oxide battery cycle, by SEM, XRD experiments on the positive and negative electrode analysis, the capacity decline is mainly attributed to the negative electrode SEI film continued consumption of Li + and LiCoO2 and HF formation Of the LiF interface film and other irreversible side effects. P.Ramadass et al. [9] established a capacity decay model by describing the process of lithium ion loss caused by the continuous growth of the negative electrode SEI film during the charge-discharge cycle. S. Sankarasubramanian et al. [10] established a capacity decay model that included the diffusion of solvent and the growth mechanism of the SEI membrane and concluded that the capacity decline was linear with the SEI film thickness and the cell aging time.
【The right way】 In the use of lithium batteries should be noted that although the battery factory are activated, but after a period of time into the dormant state, then the capacity in the virtual state. But the lithium battery is easy to activate, as long as after about 3 times the normal charge and discharge cycle can activate the battery, restore normal capacity. Due to the characteristics of the lithium battery itself, it is almost no memory effect. So the user's mobile phone in the new lithium battery in the activation process, is no need for special methods and equipment. Not only theoretically the case, from my own practice point of view, from the beginning to use 3 times the standard method of charging this "natural activation" approach is the best. 【misinformation】 For the lithium battery "activation" problem, many of the argument is: the charging time must be more than 12 hours, repeated three times in order to activate the battery. This "the first three charges to charge more than 12 hours" argument, obviously from the nickel batteries (such as nickel and cadmium and nickel hydrogen) continued to say. So this argument can be said that the beginning is misleading. Lithium batteries and nickel batteries charge and discharge characteristics of a very big difference, and can be very clear to tell you that I have read all the serious technical information are stressed overcharge and over discharge will be lithium batteries, especially liquid lithium Ion batteries cause great damage. So the best charge in accordance with standard time and standard method of charging, in particular, do not carry out more than 12 hours of long charge. Usually, the phone instructions on the charging method, is suitable for the phone's standard charging method. 【Battery killer - universal charge】 Universal charge just when the "universal" characteristics and ultra-low prices immediately make it popular north and south, not only dealers favor, consumers are more love. Universal charge to the dealer and machine friends have brought great convenience. But soon, we found that the use of universal charge, the battery was inflated more than a few times. The reason, the root of the problem or out of the universal "universal" requirements, because it should be applied to any battery, must be included in the charging voltage range of all possible batteries, then there will be "overcharge" "Full of dissatisfaction", "inflated" or even explode and so on all kinds of problems. 【Charge principle analysis】 (1) lithium battery will automatically stop after filling, but the phone will continue to power consumption, a little power consumption after the phone and immediately charge, this is full of stop - consumption of electricity and charge cycle called "trickle" charge , This state is most likely to inflate the battery. This is the first reason we are opposed to long charging (2) a long time plug the charger, can not guarantee the battery charge and discharge protection circuit characteristics never change and quality foolproof, so your battery will be a long time in the dangerous edge of the wandering. This is another reason we oppose the long charge. (3) At the same time, long charging takes a long time, often need to be carried out at night, and the situation in China's power grid, many places the night voltage is relatively high, and volatile. So this brings additional risk. 【When should you start charging in normal use?】 In our forum, you can often see this argument, because the number of charge and discharge is limited, so the phone battery should be used as much as possible to recharge the battery. But I found a test on the charge-discharge cycle of lithium-ion battery, the data on the cycle life is listed as follows: Cycle life (10% DOD):> 1000 times Cycle life (100% DOD):> 200 times Where DOD is the abbreviation of the depth of discharge. As can be seen from the table, the number of chargeable and discharge depth, 10% DOD cycle life than 100% DOD to be much longer. Of course, if the equivalent of the actual capacity of the actual charge: 10% * 1000 = 100,100% * 200 = 200, the latter fully charge and discharge or to be better, but in front of that statement to do some amendments: In case you should keep the battery in accordance with the principle of the remaining battery charge and then charge the charge, but if your battery is expected in your second day can not adhere to the whole day, it should start charging in a timely manner, of course, if you are willing to back The charger to the office and when the other. And you need to charge to cope with the expected arrival of important events that will lead to busy traffic, even when the battery has a lot of excess electricity, then you just charge in advance, because you did not really lose the "1" times the charge cycle life , That is, "0.x" times only, and often this x will be very small. The battery remaining power out of the principle of reloading is not to you to the extreme. And long charge as widely circulated a saying, is "as far as possible the battery life of mobile phones, it is best to use automatic shutdown." This practice is only the practice of nickel batteries, the purpose is to avoid the memory effect occurs, unfortunately it is also circulating in the lithium battery today. Some people because the phone battery is too low after the warning appears, still do not charge to continue to use the automatic shutdown has been used examples. The results of this example in the phone in the subsequent charge and boot are no response, had to send customer service overhaul. This is actually because the battery due to excessive discharge caused by the voltage is too low, so do not have the normal charge and boot conditions caused.
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