What is the difference between 18650 batteries and polymer batteries?

18650 batteries generally fall into two categories, one is the capacity battery and the other is the power battery. If we don't know where you use it, what kind of class you need, let me explain it to you separately.

1 capacity battery refers to the capacity of one battery. The battery with a general capacity of 3000MA or more, but the discharge capacity of this battery is relatively small, suitable for charging treasure, hand lamp, etc., continuous power consumption, but current Not required on the device.

The general brand Panasonic, Samsung, Vulcan, etc., it is sold on line.

2 power battery means that the battery capacity is not very high 2000-2400ma. However, the battery has a large discharge capacity and can reach 5C discharge, even 3C. The battery is used in equipment with relatively large currents, such as electric vehicles, and some power tools.

Power battery I use Mars on my electric car, a domestic brand.

18650 is generally packaged in steel, that is, 18650 lithium ions are in a liquid state, just like a cup filled with water, similar to this understanding. Therefore, the 18650 can only be cylindrical. If you buy a mobile power supply and see a thick and large mobile power supply, it is basically 18650 batteries.

Due to the particularity of the 18650 package (with steel shell), if the quality of the products produced is not enough, the biggest danger is the explosion. The explosion caused by the notebook in previous years is because of Sony's laptop battery (usually using 18650). There is a problem with quality control.

Lithium polymer batteries, the raw materials are generally mixed with lithium cobalt oxide, lithium manganate, and ternary lithium. Through a certain proportion of the three mixtures, a certain process is used to make the outer packaging mainly using aluminum plastic film, and the lithium material in the middle is paste. So the shape can be customized. At the same time, you can make ultra-thin batteries, such as ultra-thin batteries such as 0.33mm and 0.50mm.

The outer surface of the polymer battery is made of a layer of aluminum plastic film, and a layer of high-temperature adhesive tape is applied outside. The maximum safety of the polymer is that it leaks, short circuit, and causes the package to rise. The worst case is the burning and the flame.

Therefore, compared with the 18650, the polymer battery is safer. However, burning also poses a safety hazard, so users who use mobile power are advised not to put the mobile power on the pillows, these places on the bed.

18650 and polymer battery are the same lithium battery, 18650 market is generally lithium iron phosphate and lithium manganate and ternary, we simply talk about the ternary, ternary material 18650 price is moderate 1800mAh market The price is about 7 Yuan, the nominal voltage is 3.8V, the maximum voltage can reach 4.2V when used, the low voltage can reach 2.5V, there is no memory effect, the field of using D is also relatively wide, the domestic technical level Also ok, support for domestic. The polymer battery I have seen is mainly soft bag, power type and capacity type, the material is similar to 18650, only 18650 is stainless steel case, the polymer is aluminum plastic film case, used for industrial, transportation.

18650 is the originator of lithium-ion battery --a standard lithium-ion battery model that Japan SONY Company set in order to save cost. Among them, 18 means diameter 18mm, 65 means length is 65mm, 0 means cylindrical battery.

The common 18650 battery is divided into a lithium ion battery and a lithium iron phosphate battery. The lithium-ion battery voltage is 3.7V, the charge cut-off voltage is 4.2v, the lithium iron phosphate battery has a nominal voltage of 3.2V, the charge cut-off voltage is 3.6v, the capacity is usually 1200mAh-3350mAh, and the common capacity is 2200mAh-2600mAh. .

Lithium battery (Li-ion, Lithium Ion battery): Lithium-ion battery has the advantages of light weight, large capacity, no memory effect, etc.

18650 lithium battery

Universal Applications - Many digital devices use lithium-ion batteries for power, although they are 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 4.2Vlithiumionbattery (lithium battery) or 4.2Vlithiumsecondarybattery (lithium secondary battery), 4.2Vlithiumionrechargeablebattery (rechargeable lithium battery), so users must see the appearance of the battery block when purchasing the battery. Prevent cadmium nickel and nickel hydride batteries from being mistaken for lithium batteries because they do not see the type of battery.

Lithium batteries are the same as 3.7V or 4.2V. It’s just that the manufacturer’s label is different. 3.7V refers to the platform voltage (typical voltage) that is discharged during battery use, while 4.2 volts refers to the voltage at full charge. Common rechargeable 18650 lithium battery, the voltage is 3.6 or 3.7v standard, 4.2v when fully charged, this has little to do with the power (capacity), 18650 battery mainstream capacity from 1800mAh to 2600mAh, ( 18650 power battery capacity) More than 2200~2600mAh), the mainstream capacity even has the standard 3500 or 4000mAh or more (remind everyone, the domestically produced batteries with a nominal 3350mAH or higher in the market are likely to be fake, the current mass production capacity in China. It is 3350mAh.).

It is generally considered that the lithium battery no-load voltage is below 3.0V and it is considered that the power is used up (the specific value needs to look at the threshold of the battery protection board, such as low to 2.8V, also 3.2V). Most lithium battery discharges cannot put the no-load voltage below 3.2V, otherwise excessive discharge will damage the battery (usually the lithium battery on the market is basically used with a protective plate, so over-discharge will also cause the protection board to detect To the battery, it is impossible to charge the battery). 4.2V is the highest limit voltage for battery charging. It is generally considered that charging the lithium battery no-load voltage to 4.2V is considered to be full. During battery charging, the battery voltage gradually rises to 4.2V at 3.7V, and the lithium battery cannot be charged. Charge the no-load voltage to 4.2V or higher, otherwise it will damage the battery. This is the special place for lithium batteries.

The 18650 battery life theory is cyclic charging 1000 times. Due to the large capacity per unit density, most of it is used in laptop batteries, except

18650 lithium battery

In addition, because the stability of the 18650 at work is very good, it is widely used in various electronic fields: commonly used in high-end glare flashlights, portable power supplies, wireless data transmitters, electric heating warm clothing, shoes, portable instrumentation, portable lighting Equipment, portable printers, industrial instruments, medical instruments, etc.

The 18650 means 18 mm in diameter and 65 mm in length. The model number of the No. 5 battery is 14,500, 14 mm in diameter and 50 mm in length. Generally 18650 batteries are used in the industry, and there are few civilians. The common ones are used in laptop batteries and high-end flashlights.

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.

Charge and discharge principle

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 lithium is generated.

18650 lithium battery

The ions move through the electrolyte to the negative electrode. The carbon as the negative electrode has a layered structure, and it has many micropores. The 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 process of the lithium ion battery, the lithium ion is 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.

Charge and discharge process

Lithium battery charging control is divided into two stages. The first stage is constant current charging. When the battery voltage is lower than 4.2V, the charger will charge at a constant current. The second stage is the constant voltage charging phase. When the battery voltage reaches 4.2V, due to the characteristics of the lithium battery, if the voltage is high, it will be damaged. The charger will fix the voltage at 4.2V, and the charging current will gradually decrease. When it is reduced to a certain value (generally 1/10 set current), the charging circuit is cut off, the charging completion indicator lights up, and charging is completed.

Excessive charging and discharging of lithium-ion batteries can cause permanent damage to the positive and negative electrodes. Over-discharge leads to collapse of the negative carbon sheet structure, and collapse will cause

18650 lithium battery charger

Lithium ions cannot be inserted during charging; excessive charging causes excessive lithium ions to be embedded in the negative carbon structure, and some of the lithium ions are no longer released.

Some chargers are implemented using inexpensive solutions, which are not good enough in control accuracy, which may cause abnormal battery charging and even damage the battery. When purchasing a charger, try to choose a large brand of 18650 lithium-ion battery charger, quality and after-sales guarantee, extend the battery life. The brand-assured 18650 lithium-ion battery charger has four protections: short circuit protection, over current protection, over voltage protection, and battery reverse connection protection. Overcharge protection: When the charger overcharges the Li-ion battery, it is necessary to terminate the charging state in order to prevent the internal pressure from rising due to temperature rise. To this end, the protection device needs to monitor the battery voltage. When it reaches the battery overcharge voltage, it activates the overcharge protection function and stops charging. Over-discharge protection: In order to prevent over-discharge of the lithium-ion battery, when the lithium-ion battery voltage is lower than its over-discharge voltage detection point, the over-discharge protection is activated, the discharge is stopped, and the battery is kept in a standby mode with low quiescent current. Over current and short circuit protection: When the discharge current of the lithium ion battery is too large or a short circuit occurs, the protection device activates the over current protection function.

The page contains the contents of the machine translation.