First, what is the lithium polymer battery
The so-called lithium polymer battery refers to the use of polymer as the electrolyte lithium-ion batteries"> lithium-ion batteries, specifically divided into "semi-polymer" and "full polymer" two.
The "semi-polymer" refers to a layer of polymer (generally PVDF) coated on the isolation film, so that the bonding force of the cell is stronger, the battery can be made more rigid, and its electrolyte is still liquid electrolyte. All-polymer" refers to the use of a polymer to form a gel network inside the cell, which is then injected into the electrolyte to form the electrolyte. Although "all-polymer" batteries still use liquid electrolyte, but the amount is much less, which has greatly improved the safety performance of lithium-ion batteries. As far as I know, only SONY is now in mass production of "all-polymer" lithium-ion batteries.
On the other hand, polymer batteries refer to the use of aluminum packaging film as the outer packaging of lithium-ion batteries, which is commonly known as soft pack batteries. This packaging film consists of three layers, respectively, PP layer, Al layer and nylon layer, as PP and nylon is a polymer, so this cell is called a polymer battery.
Second, the difference between lithium-ion batteries and lithium polymer batteries
1, different raw materials
Lithium-ion battery raw materials for the electrolyte (liquid or colloid); lithium polymer battery raw materials for the electrolyte polymer electrolyte (solid or gel) and organic electrolyte.
2, different safety aspects
Lithium-ion batteries are prone to explosion in high-temperature and high-pressure environment; lithium polymer batteries use aluminum-plastic film for the shell, when the internal organic electrolyte, even if the liquid is hot, it does not explode.
3, shaping different
Polymer batteries can be thin, any area and any shape, because the electrolyte can be solid or gel rather than liquid, while lithium batteries use electrolyte, need a strong shell as a secondary packaging to accommodate the electrolyte.
4, the cell voltage is different
As polymer batteries use polymer materials, can be made in the cell multi-layer combination to achieve high voltage, while the nominal capacity of lithium battery cells is 3.6V, in order to achieve high voltage in practice, it is necessary to connect multiple cells in series to form the ideal high-voltage working platform.
5、The manufacturing process is different
The thinner the polymer battery the better the production, the thicker the lithium battery the better the production, which makes the lithium battery in the application of more expandable areas.
6、Capacity
Polymer battery capacity is not effectively increased, compared with the standard capacity of lithium batteries have been reduced.
Third, the advantages of lithium polymer batteries
1, good safety performance.
Lithium polymer batteries
In the structure of the aluminum-plastic flexible packaging, as opposed to the metal shell of the liquid cell, in the event of safety hazards, lithium-ion cells are prone to explosion, while polymer cells will only gas drum, at most, burning.
2, the thickness of small can be made thinner
Ultra-thin, the thickness can be achieved below 1mm, can be assembled into the credit card. Ordinary liquid lithium battery thickness of 3.6mm or less is a technical bottleneck, and 18650 battery is a standard volume.
3、Light weight and high capacity
The battery with polymer electrolyte does not need a metal case to protect the outer packaging, so the capacity is the same, 40% lighter than steel-cased lithium batteries, 20% lighter than aluminum-cased batteries. When the volume is generally large, the capacity of polymer batteries is greater, about 30% higher.
4、Shape can be customized
Polymer batteries can increase or reduce the thickness of the cell according to actual demand, such as a famous brand of new laptops is the use of trapezoidal polymer batteries, making full use of the internal space.
Fourth, the disadvantages of lithium polymer batteries
(1) is mainly the higher cost, because the design can be in accordance with customer demand, which the cost of research and development to be included. And the shape is variable, a wide variety, resulting in the manufacturing process of a variety of fixtures are non-standard parts, but also correspondingly increased the cost.
(2) Poor versatility of the polymer battery itself, which is also the result of flexible design, often for the difference of 1mm will need to redesign a customer.
(3) As long as it is broken, it will be ruined, and it needs to be controlled by protection circuit, overcharging or overdischarging will destroy the reversibility of the internal chemicals of the battery, which will seriously affect the life of the battery.
(4) The life span is shorter than 18650 because of the different design and material, some have liquid inside, some are dry or colloidal, and the performance is not as good as 18650 cylindrical battery when discharging at high current.
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