What are the disadvantages of polymer lithium batteries?

1. The 18650 battery is cylindrical with liquid inside. Due to the battery design and materials, the 18650 is suitable for large current. Only the super notebook, because of energy saving, can use polymer lithium battery instead of 18650 battery, especially tablet computer. Digital camera can only use 18650 similar battery, but the volume is a little small, because the charge and discharge of the flash requires large voltage and instantaneous large current.

2 advantages, polymer lithium battery, small size, large capacity, the disadvantage is that life is shorter than the 18650, because of using different design and material, some internal liquid, some are dry or is colloid, and large current discharge performance is better than 18650 cylindrical battery, so I need the large capacity electric equipment of small volume, often use lithium polymer batteries, the most typical is the performance of the mobile phone, tablets and other devices.

Source: juda large2018-04-27 hits: 1225

Generally speaking, there are two types of cell in the mobile power market, one is 18650 cell and the other is polymer cell. These two cells dominate the lithium battery industry, the vast majority of the market. In many netizens mentioned mobile power cell, mobile power network in this mobile power common two kinds of cell to do an explanation.

18650 is in the industry, namely the battery to 18 mm in diameter, length of 65 mm, cylindrical shape of battery, factory mainly Sanyo, Panasonic, Samsung, SONY, these large manufacturers, China currently has some manufacturer to produce 18650, but his reputation and influence are not three so big as described above, due to the acquisition of Sanyo, Panasonic in fact became in 18650 the world's largest production factory.

Regular size:

Generally speaking, there are 2200 mah, 2400 mah, 2600 mah, 2800 mah capacity standards. According to industry insiders, the current 18650 has achieved the maximum single section capacity of 3400mAh. If the mobile power supply is 18650 as the cell, the basic specifications are above and connected together.

18650 packing:

The 18650 is typically packaged in a steel shell, meaning that the 18650 lithium ions are liquid, like a cup filled with water, or something like that. So the 18650 can only be cylindrical, and if you're buying a portable power supply and you see a big, thick portable power supply, it's basically 18650 cells.

Due to the particularity of 18650 packaging (using steel shell), if the quality of the products produced is not up to standard, the biggest risk is the explosion. The explosion event of the notebook a few years ago was caused by the quality control problem of SONY's notebook battery (generally using 18650).

Lithium polymer cell:

The raw materials are generally lithium cobalt acid, lithium manganese acid, and lithium ternary mixed. Through a certain proportion of the three mixture, with a certain process to produce, the outer packaging is mainly using aluminum plastic film, the middle of the lithium substance for paste. So shapes can be customized. At the same time, ultra-thin batteries can be made, such as 0.33mm and 0.50mm.

Lithium polymer cell capacity:

Due to polymer battery can be any size, he has no standard shape, the general body of the product labeling for the length * width * thickness, in addition there are batteries for a plus or minus tolerance go negative aspect is the tolerance 0.5 mm, thickness tolerance of 0.55 mm (the two plus or minus tolerance, small make up some memory is not clear, I don't know whether it is right, but does not affect the reading of ordinary users, therefore instructions.) The size of the polymer depends on the volume, and also on the proportion of lithium used.

The polymer battery is coated with a layer of aluminum plastic film, and then coated with a layer of high-temperature adhesive tape. The polymer found that the biggest safety is the leakage of liquid, short circuit, leading to swelling, the worst case is to produce combustion, flame. Therefore, compared with 18650, polymer cell is better in terms of safety. However, combustion can also bring safety risks, so it is recommended to use mobile power users, try not to put the mobile power in the pillow, bed, these places.

It should be noted that security is not absolute. The safety of high quality 18650 battery is much better than that of low quality polymer battery, so the masses still need to polish their eyes to distinguish.

The 18650 will be larger than the polymer in terms of cell quality, so the polymer will be lighter in terms of portability.

The so-called polymer lithium battery refers to the use of polymer as an electrolyte lithium ion battery, specifically divided into "semi-polymer" and "full polymer" two kinds. "Semi-polymer" refers to a layer of polymer (usually PVDF) on the barrier film to make the cell more cohesive, the battery can be made harder, and the electrolyte remains a liquid electrolyte. The term "whole polymer" refers to the use of polymers to form a network of gels inside the cell and then to inject an electrolyte to form an electrolyte. Although "all-polymer" batteries still use liquid electrolytes, they use far less of them, which greatly improves the safety of lithium-ion batteries. As far as I know, only SONY produces "all-polymer" lithium-ion batteries in mass production.

On the other hand, polymer battery refers to the use of aluminum plastic packaging film as the outer package of lithium ion battery, also known as the soft pack battery. The packaging film consists of three layers, namely PP layer, Al layer and nylon layer. Since PP and nylon are polymers, this kind of cell is called polymer battery.

1. Lower price

The international price of 18650 is about 1USD/ PCS, which is about 3RMB/Ah in terms of 2Ah. And the price of polymer lithium battery, low-end copycat factory in 4RMB/Ah, 5~7RMB/Ah in the middle, in the high end of more than 7RMB/Ah. Like ATL and lishen, they can generally be sold at about 10RMB/Ah, and you are too small to accept.

2. Can not be customized

SONY has always wanted to make lithium ion batteries like alkaline batteries, with certain industrial standards, like no. 5 batteries, no. 7 batteries, basically the same all over the world. However, one of the advantages of lithium ion battery is that it can be designed according to the needs of customers, so there is no uniform standard. So far, there is only one standard model of 18650 in the lithium ion battery industry, and the rest are designed according to the needs of customers.

3. Poor security

We know that lithium ion batteries in extreme circumstances (such as overcharge, high temperature, etc.), the internal will occur violent chemical reaction, produce a lot of gas. The 18650 battery USES a metal shell with a certain strength. When the internal pressure reaches a certain level, the steel shell will burst and explode, causing a terrible safety accident.

That's why rooms that test 18650 batteries generally have to be protected with layers of protection, and no one should ever enter the room during the test. Polymer batteries do not have this problem, even in the same extreme case, because the packaging film strength is low, as long as the pressure is slightly higher will be broken, will not produce an explosion, the worst case is combustion. So polymer batteries are better than 18650 batteries in terms of safety.

4. Low energy density

In general, the capacity of 18650 battery can be about 2200mAh, so the energy density is about 500Wh/L, while the mass production of polymer battery can be close to 600Wh/L.

But polymer batteries have their drawbacks. The main reason is that the cost is relatively high. Since we can design according to customers' requirements, the research and development cost should be included. And the appearance is changeful, variety is various, bring about in manufacturing process all sorts of jig are not standard part, also increased cost accordingly. Polymer battery itself is poor in versatility, which is also brought by the flexible design, often in order to be so 1mm difference needs to be redesigned for the customer.

Iii. Application of 18650 lithium battery

The application of lithium secondary battery in the energy battery industry benefits from its superior performance. With the development of lithium secondary battery technology, it has been widely used in our daily life. Rechargeable batteries that have been used many times are increasingly popular with consumers. Pay attention to the energy battery industry, fully understand the battery so that we can do "for our own use", the current 18650 lithium battery in the following areas have some applications.

1. Energy storage

It is mainly used in base station power supply, clean energy storage, power grid power storage, household light storage system, etc.

2. Power class

Mainly refers to electric vehicles, electric bicycles, new energy vehicles.

3. Digital

Mobile phone, tablet, laptop, electric toy, MP3/MP4, earphone, charger, model airplane, mobile power supply, etc.

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