The so-called polymer lithium batteries refers to the use of polymers as the electrolyte lithium-ion batteries, specifically divided into "half-polymer" and "full polymer" two.
"Semi-polymer" refers to the isolation film coated with a layer of polymer (generally PVDF), so that the adhesion 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 polymers to form a gel network inside the cell, which is then injected into the electrolyte to form the electrolyte. Although "all-polymer" batteries still need to 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 mass-producing "all-polymer" lithium-ion batteries.
On the other hand, polymer batteries are lithium-ion batteries that use an aluminum-plastic packaging film as the outer packaging, which is commonly known as a soft pack battery. This packaging film consists of three layers, PP, Al and Nylon, and since PP and Nylon are polymers, these cells are called polymer batteries.
Two, lithium-ion batteries and lithium polymer battery difference
1, raw materials are different
Lithium-ion battery raw materials for the electrolyte (liquid or colloidal); lithium polymer batteries raw materials for the electrolyte has a polymer electrolyte (solid or gel) and organic electrolyte.
2, different security
Lithium-ion batteries are easy to explode in a high-temperature and high-pressure environment; lithium polymer batteries using aluminum-plastic film to do the shell, when the internal use of organic electrolyte, even if the liquid is very hot, but also does not explode.
3, different shape
Polymer batteries can be thin, any area and any shape, because the electrolyte can be solid or gel rather than liquid, lithium batteries use electrolyte, the need for a strong shell as a secondary packaging to accommodate the electrolyte.
4, the cell voltage is different
Because polymer batteries use polymer materials, can be made in the cell into a multi-layer combination to achieve a high voltage, and lithium battery cell nominal capacity is 3.6V, to achieve high voltage in the actual use of the battery, you need to be more than one cell in series in order to form the ideal high-voltage work platform.
5, the manufacturing process is different
The thinner the polymer battery is, the better the production, the thicker the lithium battery is, the better the production, which makes lithium batteries in the application of the expansion of more areas.
6, capacity
Polymer batteries do not effectively improve the capacity, compared with the standard capacity of lithium batteries have been reduced.
Three, the advantages of lithium polymer batteries
1, good safety performance.
Lithium polymer batteries
In the structure of the aluminum-plastic soft packaging, unlike the liquid core of the metal shell, in the event of safety hazards, lithium-ion batteries are prone to explode, while the polymer core will only drum, at most, burning.
2, the thickness of small can be made thinner
Ultra-thin, the thickness can be done below 1mm, can be assembled into a credit card. Ordinary liquid lithium battery thickness of 3.6mm or less there are technical bottlenecks, while the 18650 battery is a standard volume.
3, light weight, large capacity
The use of polymer electrolyte batteries do not need a metal shell to protect the packaging, so the capacity of the same, 40% lighter than the steel shell lithium batteries, lighter than the aluminum shell batteries 20%. When the volume is generally large, the capacity of polymer batteries is greater, about 30% higher.
4, the shape can be customized
Polymer batteries can be based on the actual demand, increase or decrease the thickness of the cell, such as a famous brand new notebook is the use of trapezoidal polymer batteries, make full use of the internal space.
Four, the shortcomings of lithium polymer batteries
(1) is mainly higher cost, because it can be designed in accordance with customer demand, which the research and development costs to be counted. And the shape is variable, a variety of types, resulting in a variety of fixtures and fittings in the manufacturing process is non-standard parts, but also a corresponding increase in costs.
(2) The polymer battery itself has poor versatility, which is also brought about by the flexible design, often for the sake of so 1mm difference will need to re-design one for the customer.
(3) As long as it is broken, it will be a total waste, and it needs to be controlled by the protection circuit, overcharging or over-discharging will destroy the reversibility of the internal chemicals of the battery, which will seriously affect the life of the battery.
(4) The life is shorter than 18650 because of the use of different designs and materials, some have liquid inside, some are dry or colloidal, and the performance is not as good as 18650 cylindrical battery when discharged with high current.