We try to find the answer by comparing the following aspects one by one.
1. Materials
Lithium batteries use liquid electrolytes, while polymer batteries use gel electrolytes and solid electrolytes. In fact, domestic polymers can not really be called polymers. It is more accurate to say that there is no liquid to flow. This is a digression and will not be discussed here.
2. Packaging method and appearance
The polymer is encapsulated with aluminum-plastic film, and the shape can be customized, thick or thin, large or small.
Lithium batteries are encapsulated in steel shell, and the most common shape is cylindrical. The most common is 18650, which refers to 18mm in diameter and 65mm in height. Fixed shape. It cannot be changed at will.
3. Safety
There is no flowing liquid in the polymer and no liquid leakage. When the internal temperature is very high, the aluminum-plastic film shell is only inflated or bulging, and will not explode. Safety is higher than lithium battery. Of course, this is not absolute. If the instantaneous current of polymer battery is large enough to short circuit, spontaneous combustion or explosion of battery will also occur. The Samsung mobile phone battery explosion a few years ago and Lenovo's recall of laptop computers due to battery defects this year are the same problems.
4. Energy density
The general 18650 battery capacity can reach about 2200mAh, so the energy density is about 500wh / L, while the energy density of polymer battery can be close to 600wh / L at this stage.
5. Cell voltage
Because polymer battery adopts polymer material, it can be made into multi-layer combination in the cell to achieve high voltage, while the nominal capacity of lithium battery cell is 3.6V. In order to achieve high voltage in practical application, multiple cells need to be connected in series to form an ideal high-voltage working platform.
It can be seen that polymer and lithium battery are better. It seems that polymer has an advantage. But the existence is reasonable. They must have something irreplaceable in different aspects.
6. Price
Generally, polymers with the same energy are more expensive than lithium batteries. But it cannot be said that this is the disadvantage of polymers.
At present, in the field of consumer electronics, such as notebook and mobile power supply, more and more polymers are used to replace lithium batteries.
In a narrow battery compartment, polymer is still needed to achieve the maximum energy density in a limited space. Because of the fixed shape of lithium battery, it can not be customized with the customer's design.
However, polymer batteries do not have a unified standard size, which in turn has become a disadvantage in some aspects. Tesla Motors adopts batteries composed of more than 7000 18650 batteries in series and parallel, plus a power control system.
It seems that whether polymer or lithium battery is better or worse depends on the specific situation, and a single conclusion cannot be given.
