The life of ternary polymer lithium battery

Energy is the cornerstone of the development of social science and technology, but now with the increasing global pollution, energy conservation and environmental protection has become the top priority of social development, at present, China vigorously advocate environmental protection, and introduced some relevant policies, so, more and more environmental protection equipment on the market. Including the reduction of gasoline cars, new energy vehicles on the market, small to charge the treasure and other products, are environmentally friendly batteries. That is, lithium battery, lithium battery than the traditional lead-acid point to say, has a short charging time, long cycle life, energy saving, environmental protection, pollution free, lightweight, long service life, and other characteristics. It has a long life, how long can it last?

The ternary lithium battery is a kind of lithium battery with positive electrode material of ternary. Lithium iron phosphate crystal has stable chemical properties. In practical use, it will not be hot or explode even when the charge is out of date or at high temperature. Lead-acid batteries have a cycle life of 500 times *, while ternary lithium batteries have a cycle life of more than 1,000 times, far exceeding that of lead-acid batteries.

According to the three-mile battery cycle 1000 times to calculate, three days a complete charge and discharge, the service life of 8.3 years, even if there is a loss process, the same can reach more than 7 years.

Lead-acid batteries depreciate at a fast rate, require constant maintenance, and last no longer than a year and a half, compared with seven years for ternary lithium batteries under the same conditions. Ternary lithium battery to adapt to the working temperature is very wide, the electric heating peak can reach 350 ℃ to 500 ℃. Compared with ordinary lead-acid batteries, the energy storage capacity is stronger, and the material is relatively light.

Ternary lithium battery does not contain any rare earth metals and heavy metals, no pollution to the environment, is a new type of green environmental protection battery. However, ternary lithium battery also has its own shortcomings, such as low-temperature environment performance is poor, the volume is greater than the same conditions of lead-acid battery, so in the development of micro-battery development is bound to have a lot of shortcomings.

As lithium battery charging, the ternary lithium battery output voltage stability, high output voltage, stable performance, large capacity, long service life, wide working temperature range, good safety and environmental protection free from contamination, so in the future development of lithium-ion batteries has a big rise in space, but also need to constantly research in order to achieve the purpose of improving its own defects.

With the growth of the world population and the continuous development of global science and technology, the use of non-renewable energy is increasing day by day, and resources are gradually facing the stage of scarcity. In order to protect the earth's environment that people temporarily rely on for survival, the protection of resources is the top priority. Therefore, the development of energy-saving and environment-friendly products is now the main event. Among the current products, energy-saving and environmental protection products are more and more popular. For example, in the battery market, lithium battery rapidly occupies part of the market by virtue of its long life, low maintenance cost, low self-discharge rate, lightweight, high voltage and other characteristics, gradually replacing the lead-acid battery. The development of a lithium battery is inevitable.

Ternary lithium battery life is in use to a certain extent, the ratio of capacity attenuation degree is calculated, directly to the capacity life of zero plantings. The industry algorithm is generally three lithium battery charge after discharge, this is called cycle life. During use, irreversible chemical reactions occur inside the lithium battery, which will lead to the decline of battery capacity, such as improper use, or extremely high temperature or extremely low temperature. For example, the decomposition of electrolyte, the inactivation of active material, and the collapse of positive and negative electrode structure lead to the reduction of the number of lithium ions embedded and unembedded, etc. Experiments show that a higher discharge rate will lead to faster capacity attenuation, if the discharge current is low, the battery voltage will be close to the balance voltage, can release more energy.

Theory of ternary lithium battery life expectancy of 1200 fully charge and discharge, which is completely cycle life, according to the use frequency, once three days fully charge and discharge, fully charge and discharge of 120 times a year, the ternary lithium battery service life to 10 years, even if in use process loss or the number of days to charge and discharge reduction, also can achieve eight years, note that said here is that the capacity of life, after eight years of ternary lithium battery capacity will be more than sixty percent, that is standard. Therefore, the real life of a ternary lithium battery is generally around 8-10 (approximate data).

Lithium iron phosphate battery: refers to the lithium-ion battery with lithium iron phosphate as the positive electrode material. It is characterized by the absence of precious elements such as cobalt, the low price of raw materials and the rich content of phosphorus and iron in the earth's resources, there will be no supply problem. It has moderate working voltage (3.2v), large electric capacity per unit weight (170mAh/g), high discharge power, quick charging and long cycle life, and high stability under high temperature and high heat environment.

Advantages compared with the more common lithium cobalt and lithium manganate batteries on the market at present, lithium iron phosphate battery has at least the following five advantages: higher safety, longer service life, free of any heavy metals and rare metals (low cost of raw materials), support for rapid charging, wide operating temperature range.

Disadvantages: lithium iron phosphate has some performance defects, such as the low density of vibration and compaction, resulting in the low energy density of lithium-ion battery; The production cost of materials is higher than that of batteries, and the yield of batteries is low with poor consistency. Poor product consistency; Intellectual property rights.

Ternary polymer lithium battery: lithium battery made of ternary anode material, Li (NiCoMn) O2. According to Ouyang Minggao of Tsinghua University, the "three-yuan" material in this survey refers to the "three-yuan" material in which the positive electrode is three-yuan and the negative electrode is graphite. And in the actual development and application, there is a positive pole is three yuan, the negative pole is lithium titanate, usually known as "lithium titanate", its performance is a relatively safe, relatively long life, do not belong to the common said "three yuan material.

Advantages of ternary lithium battery high energy density, cycle performance is better than normal lithium cobalt oxide. At present, with the continuous improvement of formula and structure, the nominal voltage of the battery has reached 3.7v, and the capacity has reached or exceeded the level of lithium cobalt oxide battery.

The ternary material power lithium battery mainly has the nickel-cobalt aluminate lithium battery, the nickel cobalt manganese acid lithium battery and so on, because the nickel cobalt aluminum high-temperature structure is not stable, causes the high-temperature security to be poor, and the pH value is too high easy to cause the monomer to expand gas, then causes the danger, at present the cost is high.

Ternary polymer lithium batteries, by contrast, do have better properties than lithium iron phosphate batteries, but why are they being held back? The key to the development of new energy vehicles is also the key to mobile digital products - the development of batteries. How to ensure that battery technology can meet the growing needs of consumers in a safe way, not only for those in the automotive technology industry but also for researchers in the whole field

When it comes to buying new energy vehicles, most consumers may think of "preferential policies" for the first time. Although this is a little embarrassing, it is indeed a very real reason. In the domestic sales environment, new energy vehicles to open up the situation, but not just because of "environmental protection" such a long way to go. The advantages of new energy vehicles in selling price and maintenance cost have indeed attracted the majority of consumers who still focus on vehicle cost.

However, some consumers may temporarily stop their curiosity about new energy vehicles for some reasons, because they will be more or less frightened by various incidents of spontaneous combustion of new energy vehicles. And that's why I'm writing this article today. It should be noted that not understanding the fundamental new energy vehicles - the pros and cons of the energy module, and do not understand the use of the process needs to pay attention to matters, in fact, and buy a time bomb in the side is no different.

Lithium iron phosphate battery: mature but not enough

Electrode materials for lithium iron phosphate is the safety of lithium-ion battery cathode material, combined with its cycle life reached more than 2000 times, the standard charging rate (5 hours) to use, can achieve the cyclical characteristics of 2000 times, coupled with the industry mature and technology threshold and the decline in the price, make many manufacturers for a variety of factors to consider using lithium iron phosphate batteries. It can be said that the rise of new energy vehicles and lithium iron phosphate battery has an inseparable relationship.

One fatal drawback of lithium iron phosphate batteries, however, is their poor performance at low temperatures, even if nano-sized and carbon-coated. Research has shown that a capacity of 3500 mah battery, if working in a - 10 ℃ environment, after less than 100 times charging and discharging cycle, power attenuation sharply to 500 mah, basic is discarded. This is not a good thing for China's vast territory, winter low temperature is more comprehensive national conditions.

In addition, the manufacturing cost of materials is higher than that of batteries, and the battery yield is low and the consistency is poor, which is also an important reason why the endurance capacity of many pure electric cars cannot reach the nominal value. Therefore, we can see that many domestic new energy vehicles (whether pure electric or hybrid electric), or some relatively cheap new energy vehicles, will choose lithium iron phosphate battery for different reasons. It can be said that the use of lithium iron phosphate battery plays an indelible fundamental role in the mass production and promotion of new energy vehicles.

Ternary polymer lithium batteries, by contrast, do have better properties than lithium iron phosphate batteries, but why have they been held back?

Ternary polymer lithium battery: the future of instability

The ternary polymer lithium battery refers to the lithium battery with the ternary positive electrode material of lithium NiCoMn (Li (NiCoMn) O2). The precursor product of ternary composite positive electrode material is made of nickel salt, cobalt salt, and manganese salt. The proportion of nickel, cobalt, and manganese in it can be adjusted according to actual needs. Ternary lithium batteries are more energy-dense, but their safety is often questioned.

The reason for this is that even though both materials will decompose at a certain temperature, lithium ternary materials will decompose at a lower temperature of about 200 degrees, while lithium iron phosphate materials will decompose at about 800 degrees. And the chemical reaction of lithium ternary materials is more intense, will release oxygen molecules, under the action of high-temperature electrolyte rapid combustion, a chain reaction. Simply put, lithium ternary materials are more likely to catch fire than lithium iron phosphate materials. It's important to note, though, that we're talking about materials, not finished batteries.

It is precise because of the safety hazards of lithium ternary materials, so manufacturers are trying to prevent accidents in the direction of. According to the characteristics of ternary lithium materials that are easy to pyrolysis, manufacturers will put a lot of efforts in the following links: overcharge protection (OVP), over discharge protection (UVP), over temperature protection (OTP) and over current protection (OCP). Therefore, the incident of spontaneous combustion should be more about whether the functions of manufacturers in these links are implemented, rather than simply throwing away food for fear of choking.

So what are the current USES of these two batteries? Let's focus on a set of data. In November, electric buses with lithium iron phosphate batteries accounted for 64.9 percent of the total, while those with ternary lithium batteries accounted for 27.6 percent. In contrast, ternary lithium batteries were installed in more than 76 percent of the all-electric passenger car market in November.

It can be seen that the ternary lithium battery itself has the advantage of greater energy density, which should be generated as a new energy storage device for future automobiles. And now the relevant safety incidents, when the popularity of new energy vehicles is still in the initial stage, can be called a good thing. In order to achieve the dual goals of market share and policy support, many enterprises related to new energy vehicles have relaxed technical requirements and produced a large number of energy components that cannot withstand repeated use for a long time. The working environment of the car is harsh, and the use of these parts for a long time will inevitably increase the cause of safety accidents.

Therefore, it can be considered that Zhang Xiangmu, director general of the department of equipment of the ministry of industry and information technology, issued an evaluation on the safety performance of the three-yuan lithium battery bus at the China electric vehicle hundred people's meeting, which is intended to define the standard from the policy level by relevant national departments to promote the generation of industry standards. Both for consumers and manufacturers, in the future, has a very positive sign. Therefore, there is no need to be hindered by the one-sided information about safety accidents of ternary lithium batteries on the Internet. All materials are dangerous, and the key is how to firmly control them.

Different types of new energy vehicle battery: unified requirements

Said the battery situation, the author thinks for the new energy vehicle situation also needs to briefly introduce the battery in the vehicle function with everybody. After all, pure electric cars are still a minority of consumers, more friends are focused on hybrid cars. And hybrid cars can be strictly divided into three types: ordinary hybrid cars, plug-in hybrid cars, and plug-in hybrid cars.

The battery capacity of the above three types of cars from small to large happens to be the ordinary hybrid car < plug-in hybrid car < + + program hybrid car. The batteries of ordinary hybrid electric cars are not rechargeable, and the batteries are used for starting and rapid acceleration. On the basis of the ordinary hybrid electric car battery, the plug-in hybrid electric car battery increases its capacity and can be charged, so it has better acceleration ability and fuel saving ability. However, the engine of the additive hybrid electric vehicle is used to drive the motor to generate electricity, which is more inclined to the pure electric vehicle.

These three models of hybrid electric vehicles have their own advantages and disadvantages. At the present stage, the main force is also general hybrid electric vehicles and plug-in hybrid electric vehicles. It is precisely because the characteristics of the three kinds of hybrid electric vehicles have something in common about the battery life and working environment that consumers should pay attention to relevant parameters, such as battery material, operating environment and optimal working state, no matter what mode of a hybrid electric vehicle is purchased. At the same time, manufacturers should also strictly control battery quality and related safety Settings in the design process to ensure safe and efficient use.

The key to the development of new energy vehicles lies in whether their user experience can match or even surpass the traditional internal combustion engine vehicles, and whether they have better advantages in purchase and after-sales. In the author's opinion, the key to the development of new energy vehicles is also the key to mobile digital products -- the development of batteries. How to ensure that battery technology can meet the growing needs of consumers in a safe way is not only the pursuit of personnel in automobile science and technology industry but also the pursuit of scientific researchers in the whole field.

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