18650 refers to the appearance specification of the battery. It is a standard battery model set by the Japanese SONY company in order to save costs. 18 means 18mm in diameter, 65 means 65mm in length, and 0 means cylindrical. shaped battery.
18650 batteries originally referred to nickel-metal hydride batteries and lithium-ion batteries. Because nickel metal hydride is not commonly used today, it refers to lithium-ion batteries. Because the positive electrode is a battery using "lithium cobalt oxide" or "lithium manganate" or the ternary material "lithium nickel cobalt manganate" as the positive electrode. Of course, there are many batteries on the market now, including batteries with lithium iron phosphate, lithium manganate and other positive electrode materials.
The nominal voltage of a single 18650 lithium-ion battery is usually 3.6V or 3.7V, the minimum discharge termination voltage is usually 2.75V, and the ordinary capacity is 1200~3100mAh.
Extended information:
Advantages of 18650 lithium battery:
1. Wide range of use
Widely used in various types of electronic equipment. For example, laptop computers, walkie-talkies, portable DVDs, instruments, audio equipment, aviation models, toys, video cameras, digital cameras, etc.
2. Series connection
Can be combined in series or parallel to form a 18650 lithium battery pack.
3. Low internal resistance
The internal resistance of polymer batteries is smaller than that of ordinary liquid batteries. The internal resistance of household polymer batteries can even be less than 35mΩ, which greatly reduces the battery's self-consumption. This polymer lithium battery that supports large discharge current is ideal for remote control models, and it has become the most promising product to replace nickel-metal hydride batteries.
4. No memory effect
No need to clear remaining power before charging, easy to use.
5. High voltage
The voltage of 18650 lithium battery is usually 3.6V, 3.8V and 4.2V, which is much higher than the 1.2V voltage of nickel-cadmium and nickel-metal hydride batteries.
6. High safety performance
18650 lithium battery has high safety performance, does not explode, does not burn; non-toxic, non-polluting, RoHS trademark certification; more than 500 cycles; good High temperature resistance, discharge efficiency up to 100% at 65 degrees. To prevent battery short circuit, the positive and negative electrodes of 18650 lithium battery are separated.
Therefore, the possibility of short circuit is minimized. Protective plates can be added to avoid overcharging and over-discharging the battery, which can also extend battery life.
7. Long life
The 18650 lithium battery has a long service life. The cycle life can reach more than 500 times during normal use, which is more than twice that of ordinary batteries.
8. Large capacity
The capacity of 18650 lithium battery is usually between 1200mah~3600mah. If 18650 lithium batteries are combined together to form a 18650 lithium battery pack, the 18650 lithium battery pack can easily exceed 5000mah.
Baidu Encyclopedia - 18650 lithium battery