The lifepo4 battery is connected with the positive pole of the battery by aluminum foil. On the left is a polymer diaphragm, which separates the positive pole from the negative pole, but the lithium ion Li can be resolved, but the electron e- cannot. On the right is the negative pole of the battery composed of carbon, which is connected with the negative pole of the battery by copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery. The battery is sealed by a metal shell. When the LiFePO4 battery is charged, The lithium ion Li in the positive electrode determines the migration of the polymer diaphragm to the negative electrode; In the process of discharge, the lithium ion Li in the negative electrode decides that the diaphragm will migrate to the positive electrode. The lithium ion battery is named because the lithium ion moves back and forth during charge and discharge.
The nominal voltage of lifepo4 battery is 3.2V, the ending charging voltage is 3.6V and the ending discharge voltage is 2.0V. Due to the different quality and process of positive and negative materials and electrolyte materials used by various lithium battery manufacturers, there will be some differences in their performance. It should be noted here that there are some differences in various performance parameters of lithium iron phosphate power batteries produced by different factories; In addition, some battery properties are not included, such as battery internal resistance, self discharge rate, charge and discharge temperature, etc.
Charge and discharge of lifepo4 battery
When the iron phosphate battery is charged, Li migrates from the 010 surface of the lithium iron phosphate crystal to the crystal appearance. Under the action of electric field force, Li enters the electrolyte, passes through the diaphragm, then migrates to the appearance of the graphite crystal through the electrolyte, and then embedded in the graphite lattice. After lithium ion is de embedded from lithium iron phosphate, lithium iron phosphate is transformed into iron phosphate; When the battery is discharged, Li is removed from the graphite crystal, enters the electrolyte, passes through the diaphragm, and then migrates to the appearance of lithium iron phosphate crystal through the electrolyte. Then it is embedded into the lattice of lithium iron phosphate through the 010 surface, and then flows to the positive electrode of lithium iron phosphate through the conductor.
Characteristics of lifepo4 battery
1. The energy storage module adopts high-capacity lithium iron phosphate cell greater than or equal to 50ah.
2. Built in high-precision IC protection circuits such as overvoltage, undervoltage, overcurrent, short circuit and temperature.
3. Optional lithium titanate material lithium battery, ultra long service life.
4. lifepo4 battery has excellent high and low temperature performance and excellent thermal insulation assembly process.
5. The only built-in professional maintenance port in the industry.
6. Special optional IP65 waterproof.
7. Optional microbms has Bluetooth communication function and supports app to manage battery.
Nowadays, most of them choose to use high-capacity lifepo4 battery as power supply, which is favored by the majority of users because of its small volume, light weight and large capacity. The higher the capacity of different models, especially batteries with different volumes, the longer the service time. We put aside the factors of volume and weight. Of course, the higher the capacity, the better. Lithium battery manufacturers will not make an issue in the modification of high-capacity standby lithium battery materials, which is completely impossible to really “improve” the capacity of the battery.
Lifepo4 battery is a secondary battery, and the main direction is power battery.
Eight advantages of Lifepo4 battery
1、Super long life. The cycle life reaches more than 2000 times, and the standard charging can reach 2000 times.
2、Safe to use. Lithium iron phosphate completely solves the potential safety problems of lithium cobalt oxide and lithium manganate. Lithium cobalt oxide and lithium manganate will explode under strong collision, posing a threat to the life safety of consumers, while lithium iron phosphate will not explode even in the worst traffic accidents after strict safety test.
3、It can be charged and discharged quickly with high current 2C. Under the special charger, the battery can be fully charged within 40 minutes after charging at 1.5C, and the starting current can reach 2c, but the lead-acid battery has no such performance.
4、High temperature resistance, the peak value of electric heating of lithium iron phosphate can reach 350 ℃ 500 ℃, while that of lithium manganate and lithium cobalt oxide is only about 200 ℃.
6、No memory effect.
7、Small size and light weight.
8、Green environmental protection.
Characteristics of Lifepo4 battery
High efficiency output: the standard discharge is 25C, the continuous high current discharge can reach 10C, and the instantaneous pulse discharge can reach 20c20c. The pulse discharge can reach 20c. Excellent service life and high safety. Even if the battery is damaged internally or externally, the battery will not burn and explode. High safety, even if the battery is damaged internally or externally, the battery will not burn and explode. Good heat resistance, and can withstand 3 ~ 5C or even higher charge and discharge speed. Good heat resistance, and can withstand 3 ~ 5C or even higher charge and discharge speed.
Good performance at high temperature: good performance at high temperature when the external temperature of the working environment is 65 ℃. There is no damage when it is over discharged to zero volts. There is no damage when it is over discharged to zero volts. Fast charging. Fast charging. Lithium iron battery raw materials do not use rare metals, which can greatly reduce the cost. Lithium iron battery raw materials do not use rare metals, which can greatly reduce the cost. No pollution to the environment. No pollution to the environment.
Application of Lifepo4 battery
1、Large electric vehicles: buses, electric vehicles, scenic spot tour buses and hybrid electric vehicles. Power car, etc.
2、Light electric vehicles: electric bicycles, golf carts, small electric scooters, stackers, cleaning vehicles, electric wheelchairs, etc.
3、Electric tools: electric drill, electric saw, lawn mower, etc.
4、Remote control cars, boats, planes and other toys.
5、Energy storage equipment for solar and wind power generation.
6、Ups and emergency lamp, warning lamp, miner’s lamp and emergency lamp.
7、Replace 3V disposable lithium battery and 9V nickel cadmium or nickel hydrogen rechargeable battery in the camera. rechargeable battery.
8、Small medical instruments and portable instruments, such as small medical instruments and portable instruments.
Life of lithium battery pack for electric bicycle
The service life of lithium battery pack is closely related to the daily use and maintenance of users.
A charging cycle means the process of all battery power from full to empty, and then from empty to full, which is not equivalent to charging once. For example, a lithium battery uses only half of its power on the first day, and then charges it slowly. If this is still the case the next day, that is, half of it is charged, and a total of two times are charged, this can only be counted as one charging cycle, not two. Therefore, it may take several times to complete a cycle. After each charging cycle, the battery capacity will be reduced a little. However, the power consumption is small, and the range is very small. After many cycles, high-quality batteries will still retain 80% of the original capacity. Many lithium battery power supply products are still used as usual after two or three years. Of course, lithium batteries still need to be replaced after their final life. The so-called 500 times means that the manufacturer has achieved about 625 rechargeable times at a constant discharge depth, reaching 500 charging cycles. Due to various effects in real life, especially the discharge depth during charging is not constant, so “500 charging cycles” can only be used as a reference battery life.
The capacity of lithium batteries will be reduced every time a charging cycle is completed, but this proportion is very small. After multiple charging cycles, high-quality lithium batteries will still retain 80% of the original battery capacity. Many lithium batteries of electric vehicles can still be used normally after three years of use, so it still depends on the quality of lithium batteries.
Method for prolonging service life of lithium battery of electric bicycle
If you want to increase the life of lithium battery of electric vehicle, you should pay attention to the following points when using it.
1. The smaller the discharge depth of the battery each time, the longer the service life of the battery. Therefore, no matter how large a lithium battery pack is used, users should develop the good habit of charging with use.
2. High current discharge will do some damage to the battery of electric bicycle, so please use the pedal to help when starting and uphill.
3. When the battery needs to be placed for a long time, the heart must be fully charged and replenished regularly, usually once 1 ~ 2 months. For users whose daily traffic distance is less than 30km, if the motor, controller, charger and other factors are good and the use method is not improper, the minimum service time of a good set of electric bicycle batteries can be guaranteed to be more than 1 year.
Method for selecting lithium battery electric bicycle
1. Look at the brand
At present, there are many electric bicycle brands. Consumers should choose brands with long operation time, low repair rate, good quality and reputation. For example, choose enterprises that have passed ISO9001-2000 certification of quality management system. If you are not sure, you can buy some big brand electric bicycles,
2. Heavy service
At present, the parts of electric vehicles are not universal, and the maintenance can not be socialized. Therefore, when selecting electric vehicles, we must pay attention to whether there is a special maintenance service department in the region. If we want to be cheap and ignore after-sales service, it is easy to be fooled.
3. Select vehicle type
Generally, electric bicycles can be divided into luxury type, ordinary type, front and rear shock absorber type and portable type. The luxury model has complete functions, but the price is high, and the ordinary model has simple structure, economy and practicality; The portable type is light and flexible, but the stroke is short. Binglan electric vehicle reminds consumers to pay attention to this when purchasing.
4. Check accessories
The strength and performance requirements of electric bicycle parts shall be higher than those of bicycles. When purchasing, the user should see the quality of the selected parts of the whole vehicle, such as whether the welding and surface of the frame and front fork are defective, whether the manufacturing of all parts is excellent, whether the double support is solid, whether the tires are famous brands, whether the fasteners are rustproof, etc.
5. Consider continuous mileage
The driving range of a new battery with a capacity of 36V / 12Ah is generally about 50km. Generally, the longest distance of riding every day is about 35km, which is more suitable (due to the influence of road conditions on the actual driving range). If the longest distance of riding every day exceeds 50km, it is necessary to consider whether there is the possibility of charging twice a day. If there is no such possibility, it is not suitable to buy electric bicycles.
Sometimes it’s not the poor quality of the electric car you buy or the bad battery, but the improper charging method leads to the premature loss of the battery.
Advantages of electric bicycle battery pack
Lithium battery has long service life, light weight and small volume
At present, the brands of lithium battery electric vehicles are diversified. The power performance of lithium battery electric bicycles is similar to that of lead-acid batteries. They can be charged for 6 ~ 8 hours. They can run 30 ~ 45 kilometers according to the battery capacity, and the weight is only about 1 / 5 of that of lead-acid batteries. The biggest advantage of lithium battery electric bicycles is long service life. The price of lithium batteries in the world is expensive only on the surface. In fact, careful calculation of the cost is similar to that of lead-acid batteries. At present, lithium batteries are generally guaranteed for 2 years and lead-acid batteries for 1 year.
Lithium battery has non activation characteristics
In the use of lithium batteries, it should be noted that after the battery is placed for a period of time, it will enter the sleep state. At this time, the capacity is lower than the normal value, and the service time will be shortened. However, the lithium battery is easy to activate. It can activate the battery and restore its normal capacity as long as it passes through 3-5 normal charge and discharge cycles. Due to the characteristics of lithium battery itself, it has almost no memory effect. Therefore, the user does not need special methods and equipment in the activation process of the new lithium battery.
Lithium battery with memory effect
When charging lead-acid batteries and nickel batteries, consumers have always worried about the memory effect of the battery. When using lithium batteries, everyone can breathe a sigh of relief. Lithium batteries do not have memory effect.
Battery pack maintenance of electric bicycle
The battery shall be recharged before initial use
The battery generally takes 1-2 months or even longer from delivery to use. During storage, the battery consumes part of the power due to spontaneous reactions such as self discharge in the battery, which can not reach the rated capacity. Therefore, it is best to supplement charging before initial use, so as to avoid customers mistaking it as insufficient capacity.
How to deal with batteries when electric vehicles are stored for a long time
Firstly, the battery should be fully charged and stored, and should be charged at least once a month to prevent power loss, which can effectively prevent irreversible salinization and crystal branch short circuit caused by crystal technology generation.
Is it better to charge the battery frequently or charge it after discharging
Because the deeper and shallower the discharge, the number of cycles will increase significantly. Therefore, according to this theory, frequent charging is beneficial to the cycle life. However, due to the influence of price factors and technical level, there are some defects such as high failure rate, poor reliability and low precision.
Therefore, sometimes frequent charging will affect the service life of the battery. When the battery is discharged and recharged, although the charging times are reduced, there will always be differences between individual batteries during discharge, which may lead to over discharge of some single cells, greatly reduce the charging acceptance capacity, resulting in insufficient charging. In addition, due to recharging after discharge, the charger has a long heavy load time and is easy to damage the charger.
Harm of overcharge and undercharge to battery
Overcharge means that the charging current of the battery is greater than the acceptable current of the battery. Overcharge is mainly the side reaction of electrolytic water. As the oxygen generated by the positive electrode of the battery is transferred to the negative electrode, oxygen compound reaction occurs and heat occurs. Therefore, the overcharge amount is actually converted into heat to increase the battery temperature. If it is not controlled, it will cause a large amount of water loss and deformation in serious cases.
Generally speaking, under charging means that if the battery is not fully charged, it is often under charged, and the pole will gradually form a kind of thick and hard lead sulfate, which is almost insoluble, that is, it will produce “irreversible sulfation”. The battery cannot be charged by ordinary methods, so the capacity will decay rapidly time by time.
In some consumer electronic products, medical equipment has more strict operating requirements for lithium-ion batteries: due to the importance of safety and reliability, there should be a powerful lithium-ion battery cell. The technology and design of lithium-ion battery for medical equipment are different from the previous battery technology. Compared with other traditional battery technologies, lithium-ion battery has the advantages of safety and environmental protection, high energy density, light weight, long cycle life and wider applicable temperature range. Therefore, it has created the successful application of lithium-ion battery for portable medical equipment.
Application of lithium ion battery in medical devices
Compared with other traditional technologies, lithium-ion batteries have many advantages in the application of medical devices. This includes higher energy density, lighter weight, longer cycle life, better battery capacity retention characteristics, and a wider applicable temperature range. With the maturity of lithium-ion battery R & D technology and the improvement of mobile work requirements of portable medical devices, lithium-ion batteries gradually occupy the leading position in the medical device industry with their absolute advantages of high voltage, high energy and long life.
Lithium ion batteries are widely used in medicine, such as hearing aids, cardiac pacemakers and other non life support devices. The use of lithium-ion battery instead of primary battery in hearing aid can solve the problems of high cost, environmental pollution and the decline of hearing aid effect caused by voltage drop. It has a wide application potential. Nowadays, a large number of monitoring instruments, ultrasonic equipment and infusion pumps have been used in the application of lithium-ion batteries in medical systems and medical devices, which can be used far away from hospitals and even battlefields. Portable devices are becoming more and more convenient to move. It is precisely because of the application of technologies such as lithium-ion batteries that the 50 pound defibrillator can be replaced by lighter, more compact and user-friendly devices without causing muscle tension to medical staff.
Maintenance of lithium ion batteries in medical devices
Due to the variety, full function and high precision of medical devices in modern clinical departments, it is very important to ensure the correct and safe use of all kinds of devices. Therefore, the effective maintenance of vulnerable parts such as lithium-ion battery in the instrument can not only prolong the service life of lithium-ion battery, but also reduce the maintenance cost of equipment and significantly improve the utilization and integrity of hospital medical equipment.
Advantages of lithium ion batteries in medical devices
1. Good safety performance: the structure of lithium-ion battery for medical devices adopts aluminum-plastic flexible packaging, which is different from the metal shell of liquid lithium-ion battery. In the case of potential safety hazards, liquid batteries are easy to explode, while medical device batteries can only be inflated at most;
2. The thickness is small and can be thinner: there is a technical bottleneck when the thickness of liquid lithium-ion battery is less than 3.6mm, but there is no technical bottleneck when the thickness of medical system and medical device battery is less than 1mm;
3. Small internal resistance: through special design, the impedance of lithium-ion battery can be greatly reduced and the high current discharge performance of lithium-ion battery can be greatly improved;
4. Very light weight: the weight of lithium-ion battery for medical devices is 40% lighter than that of steel shell lithium-ion battery with the same capacity specification and 20% lighter than that of aluminum shell battery.
With the increasing improvement of lithium-ion battery production technology and the decline of cost, the application of lithium-ion battery in the medical device market will be gradually popularized.