The working principle of lithium-ion battery refers to its charging and discharging principle. When the battery is charged, lithium ions are generated on the positive electrode of the battery, and the generated lithium ions move to the negative electrode through the electrolyte. The carbon as the negative electrode has a layered structure, and it has many micropores, and lithium ions reaching the negative electrode are embedded in the micropores of the carbon layer, and the more lithium ions are embedded, the higher the charging capacity.
By the same token, when the battery is discharged (ie, the process we use the battery), the lithium ions embedded in the carbon layer of the negative electrode come out and move back to the positive electrode. The more lithium ions return to the positive electrode, the higher the discharge capacity. What we usually call battery capacity refers to the discharge capacity.
It is not difficult to see that during the charging and discharging of a lithium ion battery, lithium ions are in a state of motion from the positive electrode to the negative electrode to the positive electrode. If we compare the lithium-ion battery to a rocking chair, the two ends of the rocking chair are the two poles of the battery, and the lithium ion is like an excellent sportsman, running back and forth at both ends of the rocking chair. Therefore, the experts gave the lithium-ion battery a cute name rocking chair battery.
The 18650 is just the size of the battery. It can be divided according to the type of battery. 18650 for lithium ion, 18650 for lithium iron phosphate, 18650 for nickel hydrogen (rare), and the common 18650 is lithium ion.
Common 18650 lithium batteries are divided into lithium ion batteries, lithium iron phosphate and nickel hydrogen batteries.
The 18650 in the 18650 lithium battery represents several dimensions: 18 refers to the battery diameter of 18.0mm, and 650 refers to the battery height of 65.0mm. Common 18650 batteries are divided into lithium ion batteries, lithium iron phosphate and nickel hydrogen batteries. The voltage and capacity specifications are 1.2V for NiMH batteries, 2500MAH for common batteries, 3.6V for Li-ion batteries, and 1500MAH-3100MAH for common sources.
Lithium Ion Battery (Li-ion, Lithium Ion Battery): Lithium-ion batteries are widely used because of their light weight, large capacity, and no memory effect. Many digital devices use lithium-ion batteries as power supplies, despite their price. Relatively expensive. Lithium-ion batteries have a high energy density, and their capacity is 1.5 to 2 times that of nickel-hydrogen batteries of the same weight, and has a very low self-discharge rate. In addition, the lithium-ion battery has almost no "memory effect" and does not contain toxic substances, which is also an important reason for its wide application. In addition, please note that the outside of the lithium battery is generally marked with English 7.2V lithiumion battery (lithium battery) or 7.2V lithium secondary battery (lithium secondary battery), 7.2V lithiumion rechargeable battery (rechargeable lithium battery), so users must purchase the battery Look at the signs on the exterior of the battery block to prevent the cadmium nickel and nickel hydride batteries from being mistaken for lithium batteries because they do not see the battery type.
The 18650 battery life theory is cyclic charging 1000 times. Because the capacity per unit density is very large, it is often used in laptop batteries. In addition, because the stability of the 18650 is very good at work, it is widely used in various electronic fields: commonly used in high-end glare flashlights, portable power supplies, wireless data. Transmitter, electric heating clothing, shoes, portable instrumentation, portable lighting equipment, portable printers, industrial instruments, medical instruments, etc.
1, large capacity 18650 lithium battery capacity is generally between 1200mah ~ 3100mah, and the general battery capacity is only about 800, if combined into a 18650 lithium battery pack, then 18650 lithium battery pack can easily break through 5000mah.
2, long life 18650 lithium battery has a long service life, the normal life cycle can reach more than 500 times, more than twice the average battery.
3, high security 18650 lithium battery safety performance, no explosion, no burning; non-toxic, non-polluting, after RoHS trademark certification; all kinds of safety performance in one go, the number of cycles is greater than 500 times; high temperature performance, 65 degrees The discharge efficiency is up to 100%. In order to prevent battery short circuit, the positive and negative poles of the 18650 lithium battery are separated. So the possibility of its short circuit has been reduced to the extreme. A protective plate can be added to prevent the battery from overcharging and over-discharging, which also extends the battery life.
4, high voltage 18650 lithium battery voltage is generally above 3.6, 3.7 or more, much higher than the 1.2V voltage of nickel-cadmium and nickel-hydrogen batteries.
5, no memory effect It is not necessary to empty the remaining power before charging, easy to use.
6. Small internal resistance: The internal resistance of the polymer battery core is smaller than that of the general liquid battery. The internal resistance of the domestic polymer battery core can even be less than 35mΩ, which greatly reduces the self-consumption of the battery and prolongs the standby of the mobile phone. Time can fully reach the level of international standards. This polymer lithium battery that supports large discharge currents is an ideal choice for remote control models and is the most promising alternative to nickel-metal hydride batteries.
7, can be combined in series or parallel to form a 18650 lithium battery pack
8, a wide range of applications Laptops, walkie-talkies, portable DVD, instrumentation, audio equipment, aircraft models, toys, cameras, digital cameras and other electronic equipment
The biggest disadvantage of the 18650 lithium battery is that his volume has been fixed. It is not very well positioned when it is installed in some notebooks or some products. Of course, this shortcoming can also be said to be an advantage. This is relative to other lithium batteries such as polymer lithium batteries. This is a disadvantage in terms of customizable and convertible size. It is an advantage over some products with specified battery specifications.
The 18650 lithium battery is prone to short circuit and explosion, which is also relative to the polymer lithium battery. If it is relatively normal, this disadvantage is not so obvious.
18650 lithium battery production needs to have a protection circuit to prevent the battery from being overcharged and discharged. Of course, this is a must for lithium batteries, which is also a disadvantage of lithium batteries, because the materials used in lithium batteries are basically lithium cobalt oxide materials, and lithium batteries of lithium cobalt oxide materials can not discharge at high current, safety Poor.
The 18650 lithium battery is generally composed of a positive electrode material and a negative electrode material.
The positive electrode material includes lithium nickelate, lithium manganate, lithium tribasic acid, lithium iron phosphate, etc., and the negative electrode material generally has an amorphous carbon material, a graphitized carbon material, a silicon-based material, a nitride, a novel alloy, and the like.