How to classify mobile phone lithium battery pool

(18650 refers to a cylindrical battery with a diameter of 18mm and a length of 65mm. Although most of the 18650 on the market are liquid lithium batteries, any statement that "polymer lithium batteries are safer than 18650 XX" is wrong. of)

What the difference between them?

First of all, it needs to be explained that the working principle of the two is the same. Both charge and discharge are realized through the process of lithium ion insertion and extraction. The insertion of lithium ions into the negative electrode is charging, and the extraction of lithium ions from the negative electrode is discharge.

From the above figure, we can see that the lithium battery cell contains the three most basic elements of the positive electrode, the negative electrode and the electrolyte (the substance filled between the two levels). Of course, there is also a separator that prevents direct contact between the positive and negative electrodes (of course, lithium Ions can pass smoothly, and if the diaphragm is not good, it will short-circuit and cause explosion~~)

The main difference between liquid lithium ion battery and polymer lithium ion battery is

1. Differences in materials: In polymer lithium battery cells, at least one of the above three basic elements must be made of polymer materials. For example, the electrolyte solution is replaced with polyacrylic acid, polymethacrylic acid and other weird things.

2. The difference in electrolyte morphology: liquid lithium-ion batteries mostly use liquid organic solvents + conductive salts, while polymer lithium battery cells replace these electrolytes with gels/solids (see battery model for specific components).

　　 What's so awesome about each of them?

polymer lithium battery/liquid lithium battery simple comparison

Lithium polymer battery Energy density of liquid lithium battery (Wh/L)>300200~280 Customizable degree (shape) Flexible and difficult, Lightweight (no need for metal protective shell), heavier (need for metal protective shell), safer, safer than safer and more expensive Cheap

1. Energy density: The greater the energy density, the more capacity a unit volume can have. The energy density of the polymer lithium battery has now reached 600Wh/L+ through the improvement of the material/thickness of the negative electrode (anode) and separator.

2. Degree of customization: The polymer lithium battery is easier to be thinner in shape, and there is no need to use a metal protective shell to wrap it, so it is easier to customize into various shapes.

3. Weight: It has been indicated on the form.

4. Safety: Under extreme conditions (such as overcharge/high temperature), the lithium battery cell will undergo a violent chemical reaction inside and produce a large amount of gas. At this time, the liquid lithium battery is wrapped by a metal shell, and when the internal pressure is quite large The shell will burst and explode, while the polymer lithium battery is only wrapped with packaging aluminum film (or plastic shell), as long as the internal pressure is slightly higher, it will expand or rupture, and will not cause an explosion. However, it should be noted that both liquid lithium batteries and polymer lithium batteries can burn under extreme conditions.

5. Cost: In addition to the higher material cost of polymer lithium batteries than liquid lithium batteries, because polymer lithium batteries can be customized to a higher degree, more costs will be incurred in the design and manufacturing process, such as each A kind of customized fixtures, test equipment, etc., cause the cost of polymer lithium batteries to be higher than that of liquid lithium batteries with standard/regular shapes.