Upload time:2020-12-30| Author:admin
Basic knowledge of batteries 100 Q&A? What is the difference between a primary battery and a rechargeable battery? The internal electrochemistry of the battery determines whether this type of battery is rechargeable. According to their electrochemical composition and the structure of the electrode, it can be known that the reaction between the internal structure of a real rechargeable battery is reversible.
Theoretically, this reversibility will not be affected by the number of cycles. Since charging and discharging will cause reversible changes in the volume and structure of the electrode, the internal design of the rechargeable battery must support this change. Since the primary battery only does Once discharged, its internal structure is much simpler and does not need to support this change. Therefore, it is not possible to charge a battery. This method is very dangerous and uneconomical. If you need to use it repeatedly, you have to choose the real number of cycles. A rechargeable battery of about 1000 times. This battery can also be called a secondary battery or storage battery. ? Is there any other difference between primary battery (hornet) and secondary battery (bee)? Another obvious difference is their energy and load capacity, and self-discharge rate. The energy of secondary batteries is much higher than that of primary batteries, but their load capacity is relatively small.
What are the advantages and disadvantages of rechargeable portable batteries? Rechargeable batteries have a long life and can be cycled more than 1,000 times. Although they are more expensive than dry batteries, they are more cost-effective if they are used frequently. The capacity of rechargeable batteries (semiconductor state) is lower than that of alkaline manganese (manganese dioxide) batteries or zinc-carbon batteries of the same specification, for example, they discharge faster.
Another disadvantage is that due to their almost constant discharge voltage, it is difficult to predict when the discharge will end. When the discharge is over, the battery voltage will suddenly drop. If you use it on a camera, suddenly the battery is discharged and you have to stop it.
But on the other hand, rechargeable batteries can provide higher capacity than most primary batteries.
However, Li-ion batteries can be widely used in photographic equipment because of their high capacity, high energy density, and the discharge voltage that gradually decreases as the depth of discharge increases. How does the rechargeable battery realize its energy conversion? Each battery has the ability of electrochemical conversion, that is, the stored chemical energy is directly converted into electrical energy, which is a secondary battery (also called a storage battery) (another term is also called a rechargeable portable battery), in the discharge process , Is to convert chemical energy into electrical energy; and during the charging process, electrical energy is converted into chemical energy again. Depending on the electrochemical system, this process can generally be charged and discharged more than 500 times, while our product li-ion can be charged and discharged more than 1,000 times. Li-ion is a new type of rechargeable portable battery. Its rated voltage is 3.2V/3.7V, and its discharge voltage will gradually decay with the depth of discharge. Unlike other rechargeable batteries, the voltage drops suddenly before discharge. ?What is a Li-ion battery? (Kids, honeycombs, fights, Binglingzi, ten brothers, demolishing houses)) Li-ion is the development of lithium batteries. So before introducing Li-ion, first introduce lithium batteries. For example, the button battery used in the camera is a lithium battery. The cathode material of lithium batteries is lithium oxide, and the anode is activated carbon. 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. It has many micropores. The lithium ions reaching the negative electrode are inserted into the micropores of the carbon layer. The more lithium ions are inserted, the higher the charging capacity. Similarly, when the battery is discharged (the process we use the battery), the lithium ions embedded in the carbon layer of the negative electrode are released and move back to the positive electrode. The more lithium ions returned to the positive electrode, the higher the discharge capacity. What we usually call battery capacity refers to discharge capacity. During the charging and discharging process of Li-ion, lithium ions are in a state of movement from positive to negative to positive. Li-ion is like a rocking chair. The two ends of the rocking chair are the two poles of the battery, and the lithium ion <a name=baidusnap0></a> runs back and forth in the rocking chair like an athlete. So Li-ion is also called rocking chair battery. What is the lithium ion manufacturing process?
1) Ingredients
Special solutions and adhesives are mixed with powdered positive and negative active materials respectively, and after high-speed stirring, the positive and negative materials are made into slurry.
2) Tu Mo
The prepared slurry is evenly coated on the surface of the metal foil, and dried to prepare positive and negative pole pieces respectively.
3) Assembly
Put the positive electrode sheet-the diaphragm-the negative electrode sheet-the diaphragm from top to bottom in the order of winding to form the battery pole core. After the electrolyte is injected and sealed, the battery assembly process is completed. Make finished batteries.
4) Formation
Use special battery charging and discharging equipment to perform charging and discharging tests on finished batteries, and test each battery. Select qualified finished batteries and wait for them to leave the factory.
How are lithium-ion safety features achieved? In order to ensure the safe and reliable use of Li-ion, experts have carried out very strict and thorough battery safety performance design to achieve battery safety assessment indicators.
1) Diaphragm 135℃ automatic shutdown protection
The international advanced Celgars2300PE-PP-PE three-layer composite film is used. When the temperature of the battery reaches 120°C, the membrane holes on both sides of the PE composite membrane are closed, the internal resistance of the battery increases, and the temperature rises inside the battery slows down. When the temperature of the battery reaches 135°C, the PP membrane pores are closed, the battery is open, and the battery is no longer Increase the temperature to ensure that the battery is safe and reliable.
2) Add additives to the electrolyte
When the battery is overcharged and the battery voltage is higher than 4.2V, the electrolyte additives polymerize with other substances in the electrolyte, the internal resistance of the battery increases greatly, a large-area open circuit is formed inside the battery, and the battery no longer heats up.
Battery cover composite structure
The battery cover adopts a scored explosion-proof ball structure. When the battery heats up, part of the gas generated during the internal activation of the battery expands, the internal pressure of the battery increases, and the pressure reaches a certain degree of score cracking and deflation.
4) Various environmental abuse tests
Conduct various abuse experiments, such as external short circuit, overcharge, acupuncture, impact, incineration, etc., to investigate battery safety performance. At the same time, the battery is subjected to temperature shock experiments and mechanical performance experiments such as vibration, drop, and impact to investigate the performance of the battery in the actual use environment.
What charge limit voltage? Rated Capacity? Rated voltage? End voltage? Charging limit voltage
According to the manufacturer's regulations, the voltage value when the battery is switched from constant current charging to constant voltage charging.
B. Rated capacity
The battery capacity indicated by the manufacturer refers to the amount of electricity that the battery should provide when the battery is discharged to the final voltage at a rate of 5h under the condition of an ambient temperature of 20℃±5℃. It is expressed by C5 and the unit is Ah (ampere hour) or mAh (milli An hour).
C. Nominal voltage
Used to represent the approximate value of the battery voltage.
D. Termination voltage
The load voltage of the battery when the discharge is terminated is specified, and its value is n*2.75V (the number of lithium-ion battery cells in series is represented by "n").
Why is the constant voltage charging current gradually decreasing? Because when the constant current process is terminated, the electrochemical poles inside the battery still maintain the same level in the entire constant current.
Under the action of the field, the concentration polarization of internal Li+ is gradually eliminated, and the migration number and speed of ions are shown as the current gradually decreasing. What is the battery capacity? The battery capacity is divided into rated capacity and actual capacity. The rated capacity of the battery refers to the stipulation or guarantee that the battery should discharge the minimum amount of electricity under certain discharge conditions during the design and manufacture of the battery. Li-ion stipulates that the battery should be charged for 3 hours under normal temperature, constant current (1C) and constant voltage (4.2V) controlled charging conditions. The actual capacity of the battery refers to the actual power released by the battery under certain discharge conditions, which is mainly affected by the discharge rate And temperature (so strictly speaking, the battery capacity should specify the charge and discharge conditions). Common units of capacity are: mAh, Ah=1000mAh). What is the internal resistance of the battery? It refers to the resistance experienced by the current flowing through the battery when the battery is working. It is composed of ohmic internal resistance and polarization internal resistance. The large internal resistance of the battery will reduce the battery discharge working voltage and shorten the discharge time. The internal resistance is mainly affected by the battery material, manufacturing process, battery structure and other factors. It is an important parameter to measure battery performance. Note: Generally, the internal resistance in the charged state is the standard. To measure the internal resistance of the battery, a special internal resistance meter must be used instead of a multimeter in the ohm range. What is open circuit voltage? It refers to the potential difference between the positive and negative electrodes of the battery when the battery is in a non-working state, that is, when there is no current flowing in the circuit. In general, the open circuit voltage of Li-ion is about 4.1-4.2V after fully charged, and about 3.0V after discharge. The battery's state of charge can be judged by the battery's open circuit voltage.
What is the working voltage? Also known as terminal voltage, it refers to the potential difference between the positive and negative electrodes of the battery when the current is over in the circuit when the battery is working. In the working state of battery discharge, when the current flows through the battery, there is no need to overcome the resistance caused by the internal resistance of the battery, so the working voltage is always lower than the open circuit voltage, and the opposite is true when charging. The discharge working voltage of Li-ion is around 3.6V. What is a discharge platform? The discharge platform is the discharge time when the battery is charged at a constant voltage until max.book118.com stops charging, and then left for 10 minutes, and discharges to 3.6V at any rate of discharge current. It is an important criterion to measure the quality of batteries.
What is the (charge and discharge) rate? Time rate?
It refers to the current value required by the battery to discharge its rated capacity within a specified time. It is equal to a multiple of the battery's rated capacity in data value, usually expressed by the letter C. For example, the nominal rated capacity of the battery is 1C (1 rate) for 600mAh, 0.5C for 300mAh, 10C for 6A (600mAh), and so on.
The hour rate is also called the hour rate. The hour refers to the number of hours required for the battery to discharge its rated capacity at a certain current. For example, the rated capacity of the battery is 600mAh, and it takes 1 hour to discharge its rated capacity with a current of 600mAh, so it is called 600mAh. The current is 1 hour rate, and so on. What is the self-discharge rate? Also known as the charge retention capability, it refers to the retention capability of the stored power of the battery under certain conditions when the battery is in an open circuit state. Mainly affected by the battery manufacturing process, materials, storage conditions and other factors. It is an important parameter to measure battery performance.
Note: A certain degree of self-discharge is normal after the battery is 100% charged and left open. According to the GB standard, LI-ion should be left open for 28 days at 20±2℃. Allowable battery capacity loss. What is internal pressure? Refers to the internal pressure of the battery, which is caused by the gas generated during the charging and discharging of the sealed battery, and is mainly affected by factors such as battery materials, manufacturing processes, and battery structure. The main reason is that the gas generated by the decomposition of moisture and organic solution inside the battery accumulates in the battery. High-rate continuous overcharge will cause the battery temperature and internal pressure to increase. In severe cases, it will have a destructive effect on the performance and appearance of the battery, such as leakage, drum bottom, increase in battery internal resistance, discharge time and cycle life Shorten etc.
Any form of overcharging of Li-ion will cause serious damage to battery performance or even explosion. Help Li-ion to use constant current and constant voltage charging during the charging process to avoid overcharging the battery.
Why do batteries need to be stored for a period of time before they can be packaged and shipped? The storage performance of the battery is an important parameter to measure the stability of the overall performance of the battery. After the battery has been stored for a certain period of time, the capacity and internal resistance of the battery are allowed to change to a certain extent. After a period of storage, the electrochemical performance of the internal components can be stabilized, and the self-discharge performance of the battery can be understood to ensure the quality of the battery. Why is it turned into? After the battery is manufactured, the internal positive and negative materials are activated through certain charging and discharging methods to improve the battery's charging and discharging performance, self-discharge, storage and other comprehensive performance. The process is called chemical conversion. The battery powder can only reflect the true performance after chemical conversion. What is the separation? In the manufacturing process of the battery, the actual capacity of the battery cannot be completely consistent due to technological reasons. The process of testing through a certain charge and discharge system and classifying the battery according to the capacity is called capacity division. What is pressure drop? Charge the battery to more than 80% qualitatively, and measure its no-load voltage. The 5W/2W resistor is used as a load to connect the positive and negative terminals of the battery as a disconnection of the battery, and the connected devices are connected in series. The voltage drop within 5 seconds after the switch is turned on is not more than 0.4V as qualified, mainly for testing the battery load performance. What is static resistance?
The internal resistance of the battery during discharge
What is dynamic resistance? The internal resistance of the battery when charging.
What is the load capacity of the battery? When the positive and negative ends of the battery are connected to the electrical appliance, the output power that drives the electrical appliance to work is the load capacity of the battery. What is charging efficiency? What is discharge efficiency? Charging efficiency refers to a measure of the degree to which the electrical energy consumed by the battery during the charging process is converted into the chemical energy that the battery can store. It is mainly affected by battery technology, formula and battery working environment temperature. Generally, the higher the environment temperature, the lower the charging efficiency.
Discharge efficiency refers to the ratio of the actual electricity discharged to the terminal voltage under a certain discharge condition to the rated capacity. It is mainly affected by the discharge rate, ambient temperature, internal resistance and other factors. Generally, the higher the discharge rate, the discharge The lower the efficiency. The lower the temperature, the lower the discharge efficiency. What is the difference between various common rechargeable batteries? At present, nickel-cadmium, nickel-metal hydride, and lithium-ion rechargeable batteries are widely used in various portable electrical equipment (such as notebook computers, cameras and mobile phones). Each rechargeable battery has its own unique chemical properties. The main difference between Ni-Cd and Ni-MH batteries is: Ni-MH batteries have higher energy density. Compared with batteries of the same type, the capacity of Ni-MH batteries is twice that of Ni-Cd batteries. This means that the use of nickel-metal hydride batteries can greatly extend the working time of the equipment without adding extra weight to the electrical equipment. Another advantage of Ni-MH batteries is: A greatly reduces the "memory effect" problem that exists in cadmium batteries, so that Ni-MH batteries can be used more conveniently. Ni-MH batteries are more environmentally friendly than Ni-Cd batteries because there are no toxic heavy metal elements inside. Li-ion has also quickly become a standard power source for portable devices. Li-ion can provide the same energy as Ni-MH batteries, but can reduce weight by about 35%. This is particularly important for electrical devices such as cameras and laptops. Said is crucial. Li-ion basically has no "memory effect" and the advantages of no toxic substances are also important factors that make it a standard power source. What are the "green batteries" currently in use and research? A new type of green and environmentally friendly battery refers to a type of high-performance, pollution-free battery that has been put into use or is being developed in recent years. At present, lithium-ion batteries, metal hydride nickel batteries, mercury-free alkaline zinc-manganese batteries that have been widely used, and lithium or lithium-ion plastic batteries, fuel cells, and electrochemical energy storage supercapacitors that are being developed are all new types. The category of green batteries. In addition, solar cells that utilize solar energy for photoelectric conversion have been widely used. What battery will dominate the battery market? As cameras, mobile and cordless phones, notebook computers, multimedia devices with images and sounds occupy more and more important positions in household appliances, compared with primary batteries,Secondary batteries, ie rechargeable batteries, are also widely used in these fields. The secondary rechargeable battery will develop in the direction of small size, light weight, capacity and intelligence. What is a lithium ion battery? It refers to a rechargeable battery that uses lithium ions as a reactive material. When the battery is discharged to the termination voltage, it can be recharged to restore to the state before discharge.
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