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Advantages And Disadvantages Of 18650 Lithium Battery
- Aug 22, 2018 -

The 18650 battery is cylindrical and has liquid inside. Because of battery design and materials, the 18650 is suitable for high current, so almost all notebooks and electric cars are designed with 18650 batteries. Only super notebooks, because of energy saving, can not use 18650 batteries. Instead, the use of polymer lithium batteries, especially tablet computers; digital cameras because of the charge and discharge of the flash requires large voltage and instantaneous large current, so only 18650 similar battery, but the volume is slightly smaller;

The advantages of polymer lithium battery, small size, large capacity, the shortcoming is that the life is shorter than 18650, because different designs and materials are used, some have liquid inside, some are dry or colloidal, and the performance is not as good as 18650 when discharging at high current. Cylindrical batteries, so the need for large-capacity and small-volume electrical equipment, usually using polymer lithium batteries, the most typical performance is mobile phones, tablets and other equipment.

Advantages of the 18650 lithium battery:

1, large capacity

The capacity of the 18650 lithium battery is generally between 1200mah and 3600mah, while the general battery capacity is only about 800. If combined into a 18650 lithium battery pack, the 18650 lithium battery pack can easily break through 5000mah.

2, long life

The 18650 lithium battery has a long service life, and the cycle life can reach more than 500 times in normal use, which is more than twice that of ordinary batteries.

3, high security performance

18650 lithium battery has high safety performance, no explosion, no burning; non-toxic, non-polluting, RoHS-certified; all kinds of safety performance in one go, the number of cycles is more than 500 times; high temperature resistance is good, discharge efficiency is up to 100% under 65 degrees . In order to prevent battery short circuit, the positive and negative poles of the 18650 lithium battery are separated. So the possibility of its short circuit has been reduced to the extreme. A protective plate can be added to prevent the battery from overcharging and over-discharging, which also extends the battery life.

4, high voltage

The voltage of the 18650 lithium battery is generally 3.6V, 3.8V and 4.2V, which is much higher than the 1.2V voltage of NiCd and NiMH batteries.

5, no memory effect

It is not necessary to empty the remaining power before charging, which is convenient to use.

6, the internal resistance is small:

The internal resistance of the polymer battery core is smaller than that of the general liquid battery. The internal resistance of the domestic polymer battery can even be less than 35mΩ, which greatly reduces the self-consumption of the battery and prolongs the standby time of the mobile phone. The level of international integration. This polymer lithium battery that supports large discharge currents is an ideal choice for remote control models and is the most promising alternative to nickel-metal hydride batteries.

7, can be combined in series or parallel to form a 18650 lithium battery pack

8, a wide range of uses

Electronic devices such as laptops, walkie-talkies, portable DVDs, instrumentation, audio equipment, model airplanes, toys, video cameras, digital cameras, etc.

As an important component of the lithium battery family, the 18650 battery was widely used in consumer electronics in the early years. In recent years, with the strong rise of new energy vehicles, 18650 batteries have also begun to be applied to the new energy automotive industry.

In addition to the old Tesla, Porsche and domestic Jianghuai, Zotye, Changan, Guangzhou Automobile, etc. have also joined the R & D team of 18650 battery models. According to industry insiders, there will be more models in the future that "fall in love" with the 18650 battery, driving a disruptive change in the way the 18650 battery is used.

18650 battery has obvious advantages

“Japanese manufacturers have accumulated a lot of experience in the production process of 18650 batteries. The 18650 batteries produced by them have reached a relatively high level of consistency and safety, and are called “standards” by the industry.” China Mini Electric Vehicles According to Luo Huiming, deputy secretary-general of the Industrial Technology Innovation Alliance, this is why Tesla will choose the Japanese 18650 battery.

Deng Lunhao, general manager of Guangxi Zhuoneng New Energy Technology Co., Ltd. also mentioned, “Because of the high degree of automation of 18650 battery production, good stability and high replaceability, the 18650 battery is modularized and standardized in system development. It has an unparalleled unique advantage, which can effectively reduce production costs and save labor.

In terms of energy density, the Model S uses 3.1Ah and an 18650 battery with an energy density of approximately 252Wh/kg. The soft pack battery used by the Toyota Leaf is 33Ah, and the energy density of the single battery is 150Wh/kg. Obviously, the 18650 battery is superior to the soft pack battery in terms of energy density. Therefore, the 18650 battery has great advantages especially when it is applied to a micro-electric vehicle.

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The miniature electric vehicle is characterized by its small size, flexible design and extremely low price. “The 18650 battery is characterized by high energy density, small size and low cost.” Sun Liqing, a professor at Beijing Institute of Technology, said that the 18650 battery can be used in a small space to achieve more load and achieve maximum utilization. In the future, the 18650 battery will be better used in the field of micro-electric vehicles, and its share will become larger and larger.

Deng Lunhao also revealed to reporters that Zhuoneng New Energy will begin mass production of 2.9Ah 18650 batteries in the second half of this year.

However, everything has its two-sidedness, and the pros and cons are the norm. In addition to the above advantages, the 18650 battery can not be ignored.

“The battery management system plays a decisive role in the operation of the power battery. The biggest drawback of the 18650 battery is that its single battery capacity is low, generally around 2~4Ah, so the number of batteries required. A lot of battery management is more complicated." Sun Liqing mentioned that this requires a thermal management system for the 18650 battery to dissipate heat. Because the internal temperature difference of the monomer is small, it is difficult to maintain the temperature difference of the entire battery pack within a suitable range.

However, the power requirement of the micro electric vehicle is between 10-20 kWh, and the demand for the 18650 battery is between 1000-2000. This is not a big test for the assembly and connection of the battery system. Several 18650 battery systems have appeared in China. Integrators to meet customer needs. At the same time, since the number of series is relatively small compared to passenger cars, it is relatively easy to manage.

For passenger cars, Tesla Motors needs 7000-8000 18650 batteries to be reliably connected into modules. "The reason why Tesla dares to use nearly 8000 18650 batteries to connect into modules, mainly based on good quality batteries. And unparalleled welding technology." Deng Lunhao believes that although the 18650 battery is defective, it does not hinder its integration into the power battery family.

For power batteries, in addition to safety, energy density, and cruising range, there is a very important assessment standard, which is the cycle life. From the test data, the cycle life of the 18650 battery is generally between 500 and 1000 times, which is lower than the 2000 times of the soft pack battery, which limits the application range of the 18650 battery to some extent.

Keep moving forward in controversy

It is reported that among the various types of 18650 batteries, the shipments topped the list with 2.2Ah products, accounting for about 40% of the total shipments of 18650 batteries. Thanks to the rapid development of new energy vehicles, the shipment of 18650 batteries larger than 2.6Ah has gradually increased to about 40%, becoming the “new main force” for the sales of 18650 batteries.

At present, the main domestic 18650 battery companies are Foster, Zhuoneng, BAK, Lishen, etc. The major foreign 18650 battery companies include Samsung, Panasonic, and LG Chem. According to relevant data, in 2015, South Korea's Samsung annual production capacity reached 700 million, Japan's Matsushita annual production capacity is close to 300 million, while Foster and Zhuoneng and other companies have an annual production capacity of less than 100 million.

In response to this situation, Deng Lunhao explained, "The annual production capacity of China's 18650 battery is not as good as that of South Korea and Japan. The main reason is that China's 18650 battery started late and the development is relatively slow. Although the current annual domestic production capacity is not satisfactory, the new energy industry continues to be hot, 18650 The battery market is only a matter of time, after all, it offers more choices for new energy vehicles.

At the same time, a large number of well-known listed companies have entered the 18650 battery industry. In 2015 alone, five listed companies “arranged” to 18650 batteries. According to statistics, the five listed companies invested a total of 6.558 billion yuan, which is undoubtedly a "cardiotonic agent" for the 18650 battery industry. At the same time, the company's former servant force on the 18650 battery, but also proves that the 18650 battery market prospects are clear.

Although the prospects are clear, it must be mentioned that although the current power lithium battery industry has formed a competitive landscape of China, South Korea and Japan, the output of the three countries accounts for more than 90% of the global total. However, the technical level of China's battery production still lags behind that of Japan and South Korea, and there are only a handful of companies that can produce high-quality products.

"The domestic 18650 battery industry is in the situation of 'internal and external troubles'. First, competition from other batteries, such as square batteries, soft pack batteries, etc.; Second, competition from foreign 18650 battery market, such as South Korea's Samsung, Japan's Panasonic Wait, its market environment is not too optimistic." Deng Lunhao told reporters.

According to industry insiders, although the number of companies investing in 18,650 batteries is increasing, most of them have not been able to optimize the performance of their batteries according to the requirements of the whole vehicle. However, the requirements for batteries for micro electric vehicles have not been specifically quantified. The indicator, which also brings great challenges to the promotion of 18650 battery.

Fortunately, the "New Energy Vehicle Manufacturing Enterprise and Product Access Management Rules (Revised Edition)" bundles the recommended catalogue of new energy vehicles with the "Regulations for Automotive Power Battery Standards" (hereinafter referred to as "Standard Conditions") and has entered new energy sources. In order to obtain the national new energy vehicle subsidy, it is necessary to provide a power battery that meets the “Regulations” at the same time.

For this policy, Sun Liqing explained, “This means that the “Regulations” will become mandatory standards. This change will increase the access threshold of the 18650 battery industry, forcing companies to focus on the scale and quality of 18650 battery production.” Small or low-cost 18650 battery companies will face a phase out or face mergers and acquisitions.

"18650 battery is not bad, compared with polymer batteries, there are still many advantages. Only the battery made by domestic manufacturers is relatively poor in safety and stability, and the name is broken. In the future, the domestic 18650 battery is defeated or dominated. It depends on whether China's 18650 battery can improve itself." Luo Huiming added.


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