1. What is the difference between primary batteries and rechargeable batteries?
The electrochemistry inside the battery determines whether this type of battery is rechargeable. According to their electrochemical composition and the structure of the electrodes, it can be seen that the reactions occurring between the internal structures of a true rechargeable battery are 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 a primary battery only does Once discharged, its internal structure is much simpler and does not need to support this change. Therefore, the primary battery cannot be charged. This approach is very dangerous and uneconomical. If it needs to be used repeatedly, there are various rechargeable batteries. Batteries may also be called primary batteries or accumulators.
2. Are there any other differences between primary batteries and secondary batteries?
The obvious difference is their energy and load capacity, as well as self-discharge rate. The energy of secondary batteries is much higher than that of primary batteries, but their load capacity is relatively small.
3. What are the advantages and disadvantages of rechargeable portable batteries?
Rechargeable batteries have a long life and can be cycled more than 300 times. Although they are more expensive than dry batteries, they are more cost-effective if used frequently. Rechargeable batteries have a lower capacity than alkaline-manganese or zinc-carbon batteries of the same specification; for example, they discharge faster.
Another disadvantage is that due to their nearly constant discharge voltage, it is difficult to predict when the discharge will end. When the discharge ends, the battery voltage will suddenly drop. If you are using it on a camera, and the battery suddenly runs out of power, you have to stop.
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 discharge voltage that gradually decreases with the increase of discharge depth.
4. How does a rechargeable battery achieve its energy conversion?
Each battery has the ability to electrochemical conversion, that is, to directly convert stored chemical energy into electrical energy. As far as secondary electrons (also called batteries) are concerned (another term is also called rechargeable portable batteries), during the discharge process , converts chemical energy into electrical energy; and during the charging process, it converts electrical energy into chemical energy again. This process depends on the electrochemical system. Generally, it can be charged and discharged more than 300 times, while our product li-ion can be repeatedly charged and discharged more than 500 times. Li-ion is a new type of rechargeable portable battery. Its rated voltage is 3.7V, and its discharge voltage will gradually decline with the depth of discharge. Unlike other rechargeable batteries, the voltage suddenly drops before discharge.
5. What is Li-ion battery?
Li-ion is developed from lithium batteries. So before introducing Li-ion, let’s introduce lithium batteries first. For example, the button batteries used in cameras in the past were lithium batteries. The positive electrode material of lithium batteries is lithium metal, and the negative electrode is 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 used as the negative electrode has a layered structure with many micropores. The lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer. The more lithium ions are embedded, the higher the charging capacity. Similarly, when the battery is discharged (that is, the process in which 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 the discharge capacity. During the charging and discharging process of Li-ion, lithium ions are in a state of movement from positive electrode → negative electrode → positive electrode. Li-ion is like a rocking chair. The two ends of the rocking chair are the poles of the battery, and the lithium ions are like athletes running back and forth in the rocking chair. So Li-ion is also called a rocking chair battery.
6. What are the components of a Li-ion battery?
(1) Upper and lower battery covers (2) Positive electrode - the active material is lithium cobalt oxide (3) Separator - a special composite membrane
(4) Negative electrode - the active material is carbon (5) Organic electrolyte (6) Battery shell (divided into steel shell and aluminum shell)
7. What are the advantages of Li-ion batteries? What are the disadvantages?
Li-ion has the following advantages:
1) The working voltage of a single battery is as high as 3.6-3.8V:
2) Large specific energy. The current actual specific energy that can be achieved is 100-115Wh and 240-253Wh/L (2 times that of Nl-Cd, 1.5 times that of Ni-MH). In the future, with the development of technology, the specific energy can be as high as 150Wh. and 400 Wh/L
3) The cycle life is long, generally more than 300 times, or even 500 times. For electrical appliances with small current discharge, the service life of the battery will double the competitiveness of the electrical appliance.
4) Good safety performance, no pollution, and no memory effect. As the predecessor of Li-ion, lithium batteries easily form dendrites and cause short circuits, which reduces their application fields: Li-ion does not contain cadmium, lead, mercury, etc. Elements that pollute the environment: A major drawback of Ni-Cd batteries with some processes (such as sintered) is the "memory effect", which seriously restricts the use of batteries, but Li-ion does not have this problem at all.
5) Small self-discharge
The self-discharge rate of fully charged Li-ion after one month of storage at room temperature is about 10%, which is much lower than the 25-30% of Ni-Cd and the 30-35% of Ni and MH. Li-ion also has certain shortcomings, such as:
1) Battery cost is higher. Mainly manifested in the high price of LiCoO2 (the resource of Co is small) and the difficulty in purifying the electrolyte system.
2) High current discharge is not allowed. Due to reasons such as the organic electrolyte system, the internal resistance of the battery is larger than that of other types of batteries. Therefore, a smaller discharge current density is required. Generally, the discharge current is below 0.5C, which is only suitable for electrical appliances with small and medium currents.
3) Need to protect line control.
A. Overcharge protection: Overcharging the battery will destroy the positive electrode structure and affect performance and life; at the same time, overcharging will cause the electrolyte to decompose, and the internal pressure will be too high, causing leakage and other problems; therefore, it must be under a constant voltage of 4.1V-4.2V Charge;
B. Over-discharge protection: Over-discharge will cause difficulty in the recovery of active materials, so protection circuit control is also required.
8. What is the lithium-ion manufacturing process?
1) Ingredients
Special solutions and adhesives are used to mix the powdered positive and negative active materials respectively, and after stirring at high speed, the positive and negative electrode materials are made into slurry.
2) Tu Mo
The prepared slurry is evenly coated on the surface of the metal foil and dried to form positive and negative electrode plates respectively.
3) Assembly
Place the positive electrode sheet - separator - negative electrode sheet - separator in the order from top to bottom, and then roll it into a battery core. After injecting electrolyte, sealing and other processes, the battery assembly process is completed. Made into finished batteries.
4) Formation
Use special battery charging and discharging equipment to conduct charge and discharge tests on the finished batteries, and test each battery. Qualified finished batteries are screened out and ready to leave the factory.
9. How are lithium-ion safety features implemented?
In order to ensure the safe and reliable use of Li-ion, experts have carried out very strict and careful battery safety performance design to meet battery safety assessment indicators.
1) Diaphragm automatically shuts off protection at 135°C
Using the internationally advanced Celgars2300PE-PP-PE three-layer composite membrane. When the temperature of the battery reaches 120°C, the membrane holes on both sides of the PE composite film close, the internal resistance of the battery increases, and the temperature rise inside the battery slows down. When the temperature of the battery reaches 135°C, the PP film holes close, the battery is internally broken, and the battery no longer Increase the temperature to ensure the safety and reliability of the battery.
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 significantly, a large-area open circuit is formed inside the battery, and the battery no longer heats up.
3) 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 process of the battery expands, and the internal pressure of the battery increases. When the pressure reaches a certain level, the score ruptures and deflates.
4) Abuse testing in various environments
Conduct various abuse experiments, such as external short circuit, overcharge, acupuncture, impact, incineration, etc., to examine the battery safety performance. At the same time, temperature shock experiments and mechanical performance experiments such as vibration, drop, and impact were conducted on the battery to examine the performance of the battery in the actual use environment.
10. What is the charging limit voltage? Rated Capacity? Rated voltage? Termination voltage?
A. Charging limit voltage
According to the manufacturer's regulations, the voltage value when the battery changes from constant current charging to constant voltage charging.
B. Rated capacity
The battery capacity indicated by the manufacturer refers to the power that the battery should provide when the battery is discharged to the end voltage at a rate of 5 hours under the condition of an ambient temperature of 20℃±5℃. It is expressed by C5 and the unit is Ah (ampere hour) or mAh (millimeter). hours).
C. Nominal voltage
Used to represent the approximate value of battery voltage.
D. Termination voltage
Specifies the load voltage of the battery when discharge is terminated, and its value is n*2.75V (the number of series connected lithium-ion single cells is represented by "n").
11. Why does the constant voltage charging current gradually decrease?
Because when the constant current process terminates, the electrochemical polarization inside the battery still maintains the same level during the entire constant current process.
Under the action of the field, the concentration polarization of internal Li+ is gradually eliminated, and the migration number and speed of ions show a gradual decrease in current.
12. What is the capacity of the battery?
The capacity of the battery 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 when designing and manufacturing the battery. Li-ion stipulates that the battery should be charged for 3 hours under charging conditions controlled by normal temperature, constant current (1C), and constant voltage (4.2V). The actual capacity of the battery refers to the actual amount of electricity released by the battery under certain discharge conditions, which is mainly affected by the discharge rate. and the influence of temperature (so strictly speaking, the battery capacity should specify the charging and discharging conditions). Common units of capacity are: mAh, Ah=1000mAh).
13. What is battery internal resistance?
It refers to the resistance to current flowing through the interior of the battery when the battery is working. It consists of two parts: ohmic internal resistance and polarization internal resistance. A large internal resistance of the battery will cause the battery discharge working voltage to decrease and the discharge time to shorten. The internal resistance is mainly affected by factors such as battery materials, manufacturing processes, and battery structure. It is an important parameter to measure battery performance. Note: Generally, the internal resistance in the charging state is used as the standard. To measure the internal resistance of the battery, you need to use a special internal resistance meter to measure it, rather than using the ohm range of a multimeter.
14. What is open circuit voltage?
It refers to the potential difference between the positive and negative electrodes of the battery when the battery is not working, that is, when no current flows through the circuit. Under normal circumstances, the open circuit voltage of Li-ion after full charge is about 4.1-4.2V, and the open voltage after discharge is about 3.0V. The battery's state of charge can be judged by the battery's open circuit voltage.
15. What is the working voltage?
Also called terminal voltage, it refers to the potential difference between the positive and negative electrodes of the battery when the battery is in working condition, that is, when there is current in the circuit. In the battery discharge working state, when current flows through the interior of the battery, it does not need to overcome the resistance caused by the battery's internal resistance, so the operating voltage is always lower than that of the open-circuit battery, and the opposite is true during charging. The discharge operating voltage of Li-ion is around 3.6V.
16. What is a discharge platform?
The discharge platform is the discharge time when the voltage is charged at a constant voltage to 4.2V and the current is less than 0.01C, then left aside for 10 minutes, and discharged to 3.6V at any rate of discharge current. It is an important standard to measure the quality of the battery.
17. What is (charge and discharge) rate? Hourly rate?
It refers to the current value required when the battery releases its rated capacity within a specified period of time. Its data value is equal to a multiple of the battery's rated capacity, usually represented by the letter C. For example, if the nominal rated capacity of the battery is 600mAh, it is 1C (1 rate), 300mAh is 0.5C, 6A (600mAh) is 10C, and so on.
The hour rate is also called the hour rate, which refers to the number of hours it takes for the battery to discharge its rated capacity with 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 a 1 hour rate, and so on.
18. What is self-discharge rate?
Also known as charge retention capacity, it refers to the ability of the battery to maintain the power stored in the battery under certain conditions when the battery is in an open circuit state. Mainly affected by battery manufacturing process, materials, storage conditions and other factors. It is an important parameter to measure battery performance.
Note: After the battery is 100% charged and left open, a certain degree of self-discharge is normal. After the GB standard stipulates that LI-ion should be opened and left open for 28 days at 20±2℃. Battery capacity loss is allowed.
19. What is internal pressure?
Refers to the internal air pressure of the battery, which is caused by the gas generated by the sealed battery during the charge and discharge process. It 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 solutions inside the battery accumulates in the battery.
Continuous overcharging at high rates will cause the battery temperature and internal pressure to increase. In serious cases, it will have destructive effects on the performance and appearance of the battery, such as leakage, bottom bulging, increased internal resistance of the battery, discharge time and cycle life. Shorten etc.
Any form of excess Li-ion will cause severe damage to battery performance or even explosion. Li-ion needs to use constant current and constant voltage charging during the charging process to avoid overcharging the battery.
20. 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 battery's comprehensive performance. After the battery is stored for a certain period of time, the battery capacity and internal resistance are allowed to change to a certain extent. After a period of storage, the electrochemical properties 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.
21. Why should it be transformed?
After the battery is manufactured, the internal positive and negative materials are activated through a certain charge and discharge method to improve the battery's charge and discharge performance, self-discharge, storage and other comprehensive properties. This process is called formation. Battery powder can only reflect its true performance after it has been formed.
22.What is volume distribution?
During the manufacturing process of the battery, the actual capacity of the battery cannot be completely consistent due to process reasons. The process of testing the battery through a certain charge and discharge system and classifying the battery by capacity is called capacity classification.
twenty three. What is pressure drop?
Qualitatively charge the battery to more than 80%, and measure its no-load voltage. The 5W/2W battery is used as a load to connect the positive and negative terminals of the battery, and the switch is used as a circuit breaker and path device for the battery in series. If the voltage drop is no more than 0.4V 5 seconds after turning on the switch, it is qualified, mainly to test the battery load performance.
twenty four. What is static resistance?
That is, the internal resistance of the battery during discharge
25. What is dynamic resistance?
That is the internal resistance of the battery during charging.
26. What is the load capacity of the battery?
When the positive and negative ends of the battery are connected to an electrical appliance, the output power that drives the electrical appliance to work is the load capacity of the battery.
27.What is charging efficiency? What is discharge efficiency?
Charging efficiency refers to a measure of the degree to which the electrical energy consumed by a battery during charging is converted into chemical energy that the battery can store. It is mainly affected by the battery process, formula and the working environment temperature of the battery. Generally, the higher the ambient temperature, the lower the charging efficiency.
Discharge efficiency refers to the ratio of the actual amount of electricity released to the rated capacity when discharging to the end voltage under certain discharge conditions. It is mainly affected by factors such as discharge rate, ambient temperature, internal resistance, etc. Generally speaking, the higher the discharge rate, the higher the discharge rate. The lower the efficiency. The lower the temperature, the lower the discharge efficiency.
28. What are the differences between the various rechargeable batteries currently common?
Currently, nickel-cadmium, nickel-metal hydride, and lithium-ion rechargeable batteries are widely used in various portable electrical devices (such as laptops, cameras, mobile phones, etc.). Each rechargeable battery has its own unique chemical properties. The main difference between nickel-cadmium and nickel-metal hydride batteries is that nickel-metal hydride batteries have a higher energy density. Compared with batteries of the same type, the capacity of nickel-metal hydride batteries is twice that of nickel-cadmium batteries. This means that using nickel-metal hydride batteries can greatly extend the operating time of the device without adding extra weight to the powered device. Another advantage of nickel-metal hydride batteries is that it greatly reduces the "memory effect" problem that exists in cadmium batteries, making nickel-metal hydride batteries more convenient to use. Nickel metal hydride batteries are more environmentally friendly than nickel cadmium batteries because there are no toxic heavy metal elements inside them.
Li-ion has also quickly become the standard power source for portable devices. Li-ion can provide the same energy as nickel-metal hydride batteries, but can reduce the weight by about 35%, which is suitable for power-consuming devices such as cameras and laptops. is crucial. The fact that Li-ion has no "memory effect" and no toxic substances is also an important factor in making it a standard power supply.
32. Comparison of technical parameters of Ni, Cd, NiMH and Li-ion.
Battery Type Item Nickel Cadmium Rechargeable Nickel Metal Hydride Rechargeable Lithium Ion Rechargeable Battery
Weight specific energy 50 65 105-140
Volume specific energy 150 200 300
Charge and discharge life 500 500 1000
Self-discharge rate (%) 25-30 30-35 6-9
Is there a memory effect? Yes No No
Is there any pollution? Yes No No
Note: The charging rate is 1C
29. What are the “green batteries” currently in use and researched?
New green environmentally friendly batteries refer to a type of high-performance, pollution-free batteries that have been put into use or are being developed in recent years. At present, lithium-ion batteries, metal hydride nickel batteries, mercury-free alkaline zinc-manganese batteries that are being promoted and used, as well as lithium or lithium-ion plastic batteries, combustion batteries, and electrochemical energy storage supercapacitors that are being developed are all new types. The category of green environmentally friendly batteries. In addition, solar cells that use solar energy for photoelectric conversion have been widely used.
30. What battery will dominate the battery market?
As cameras, mobile and cordless phones, notebook computers, and multimedia devices with images and sounds occupy an increasingly important position in household appliances, compared with primary batteries, secondary batteries, that is, rechargeable batteries, are also widely used. in these fields. Secondary rechargeable batteries will develop in the direction of small size, light weight, high capacity and intelligence.
31. What is a lithium-ion battery?
It refers to a rechargeable battery with lithium ions as the reactive material. When the battery is discharged to the end voltage, it can be recharged to return to the state before discharge.
32. How does a lithium-ion battery work?
During discharge, lithium in the intercalated compound of lithium and carbon dissolves from the negative electrode to form lithium ions into the electrolyte, passes through the electrolyte and is embedded in the cathode crystal to form an intercalated compound. During charging, the lithium ions embedded in the cathode return to the electrolyte. into the electrolyte, and then forms an intercalation compound with carbon on the negative electrode, and the cycle begins again.
33. What are the advantages of lithium-ion batteries compared with nickel/cadmium, nickel/hydrogen, and lead-acid batteries?
High specific energy, low self-discharge rate, good high and low temperature performance and long charge and discharge life.
34. What is the average voltage of the battery?
When the battery is discharging, the average voltage from the beginning to the end of the discharge.
35. What is the energy density of a battery?
Refers to the electrical energy contained in the unit volume of the battery.
36. What is the capacity of the battery?
Refers to the electric energy that can be released by the active materials in the battery participating in the electrochemical reaction, which is called the capacity of the battery.
37. What is the design capacity of the battery?
According to the amount of active material contained in the battery, the capacity of the battery calculated from electrochemical theory is called the design capacity.
38. What is the rated capacity of the battery?
It refers to the capacity that the battery can reach after it is designed and affected by the battery manufacturing process, which is called rated capacity.
39. What is the operating temperature range of lithium-ion batteries?
Charging -10—45℃ Discharging -30—55℃
40. What is the rate of battery discharge?
It refers to the ratio relationship between the discharge current (A) and the rated capacity (A·h) during discharge.
41. What is the hourly discharge rate of the battery?
The number of hours required to discharge the rated capacity according to a certain output current is called the discharge hour rate.
42. What raw materials do lithium-ion batteries consist of?
It is composed of positive active material, negative active material, current collector, separator, electrolyte, casing and other materials.
43. Which characteristics of the battery are related to the lithium-ion battery model?
The appearance length, width and height of the battery and the capacity of the battery.
44. What are the two most important factors that affect the cycle performance of lithium-ion batteries?
The nature of the active substance and the type and content of impurities.
45. How to control the moisture inside the battery during the production process?
1. Be moisture-proof and moisture-proof.
2. Shorten the operation time and reduce the exposure time of the pole piece in the air.
3. Carry out baking operations reasonably and correctly.
4. Try to work in a dry environment.
46. What is the active cathode material of lithium-ion batteries?
Lithium salts; such as lithium cobalt oxide, lithium manganate, lithium nickel oxide, etc.
47. What is the active negative electrode material of lithium-ion battery?
graphite powder
48. Why do conductive agents need to be added to electrode materials?
When the battery is working, the active material of the battery will not dissolve in the electrolyte regardless of charging or discharging. In order to enhance the conductivity of the active material and the grid and current collector, a conductive agent is added.
49. What is the composition of the electrolyte of lithium-ion batteries?
Commonly used ones are lithium hexafluorophosphate, lithium tetrafluorophosphate (LiPF6, LiClO4), etc.
50. What is the purpose of ingredients?
The active material is evenly dispersed, which facilitates even sizing and constant sizing amount.
51. Three basic parameters for drawing positive and negative electrode sheets
Slurrying temperature, speed, dressing amount.
52. How to control the amount of dressing on the pole piece?
According to the solid content and specific gravity of the positive and negative electrode slurries, adjust the tool gap of the pulping machine head and control the thickness of the pulping to achieve control.
53. How to judge the quality of pole pieces during the pulping process?
The pole pieces whose surface is flat, smooth, evenly dressed, have good adhesion, are dry, and do not peel off, fall off, lack of material, have no dust, scratches, or bubbles are considered good pole pieces, and those that are defective are considered good pole pieces. Bad pole piece.
54. Main equipment for cutting positive and negative electrode sheets
Guillotine, shears.
55. Main precautions for positive and negative electrode plates
1. Check whether there are burrs or unevenness on the knife edge, and pay attention to the safety of the knife when working.
2. The knives used for cutting positive and negative electrodes cannot be mixed.
3. Check the quality of the pole pieces at any time during the cutting process, separate the unqualified ones into different grades, and do not mix them up.
4. The cut pieces will be immediately transferred to subsequent processes after inspection.
56. What is the purpose of positive baking of positive and negative electrodes?
Remove water and organic solvents from the pole piece.
57. What is the purpose of pressing positive and negative electrode sheets?
Make the active material in close contact with the grid and current collector, reduce the moving distance of electrons, reduce the thickness of the pole piece, increase the filling volume, and improve the utilization rate of the battery volume. Thereby increasing the capacity of the battery.
58. What effect does the tablet thickness have on battery performance?
When the thickness of the tablet is too thick, it is easy to reduce the amount of active material in the battery, reduce the amount of active material per unit volume and increase the polarization potential, thereby reducing the capacity of the battery.
When the thickness of the tablet is too thin, it is easy to increase the amount of active material in the battery and reduce the effective area of the electrode surface, resulting in a waste of active materials and difficulties in large current flow.
59. What is the purpose of pole piece weighing?
Accurately understand and master the dressing amount of pole pieces.
60. What is the purpose of accompanying films?
Keep the proportion of active materials on the positive and negative electrode sheets consistent.
61. Why is it necessary to perform brushing operation?
Remove dust, material accumulation, burrs, etc. on the pole pieces.
62. What tabs are used for the positive electrode?
Use aluminum strip tabs.
63. What tab is used for the negative electrode?
Nickel strap tabs are used.
64. Equipment for welding tabs?
Use an ultrasonic welder for the positive electrode and a spot welder for the negative electrode.
65. What impact does the humidity in the winding workshop have on battery quality?
When the humidity in the winding room is high, the pole pieces absorb a large amount of water, which increases the moisture content of the pole pieces, increases the amount of gas produced in the battery, increases the internal pressure of the battery, and endangers the safety performance of the battery. The increase in water content consumes more active substances in the battery, causing the battery capacity to decrease. On the contrary, the humidity is low,
66. What are the functions of air conditioners and dehumidification systems in the winding workshop?
Maintain a constant indoor temperature and reduce indoor humidity to improve battery performance.
67. Can the floor of the winding workshop be wiped with water?
Can't
68. What are the main precautions when winding battery cells?
1. Align the pole piece and diaphragm paper. When pressing the pole piece and diaphragm paper with your hands, use moderate and even force. The battery core is wound with appropriate tightness.
2. Pay attention to whether there are scratches, missing materials, missing materials, pores, bubbling and other defects on the pole pieces and whether there are defects in the diaphragm paper. If there are any defects, dispose of them as scrap.
3. When winding, pay attention to the coordination of hands and feet to avoid scratching your hands by the winding needle.
69. What is the purpose and location of adhesive tape on battery cells?
The position of the battery core sticker will not deform after the battery core is rolled and formed. The adhesive tape on the bottom prevents the bottom of the positive electrode in the battery cell from contacting the battery casing and causing a short circuit. The side stickers prevent the battery core from deforming after being rolled and formed. The adhesive tape on the bottom prevents the bottom of the positive electrode in the battery cell from contacting the battery casing and causing a short circuit in the battery.
70. What equipment is used to weld the tabs to the cover plate?
Ultrasonic and butt welding machines.
71. What are the battery cell resistance requirements?
Greater than 20MΩ
72. What should I do if the resistance of the battery core does not meet the requirements?
Repair
73. Why do the tabs need to be taped?
Increases firmness and prevents short circuits caused by contact between tabs.
74. What inspections are required before the battery cover is used?
Inspection of overall dimensions, shape, thickness, insulation, sealing, corrosion resistance, material retention and other items.
75. What is the maximum pressure that the battery cover can withstand?
0.4Mpa
76. How to prevent battery leakage?
To prevent battery leakage, you should do the following:
1. When welding the battery shell and cap, the welding should be firm and sealed. There should be no leakage or weak welding, and no cracks, cracks or other defects in the welding seam.
2. When sealing with steel balls, the size of the steel balls should be appropriate and the material of the steel balls should be the same as the material of the cap. The welds have no rips, cracks and are solid.
3. The positive electrode of the cap is tightly connected without gaps, and the insulating sealing gasket has appropriate elasticity, is corrosion-resistant, and is not prone to aging.
77. How to prevent unsealed batteries from absorbing water in the workshop under existing conditions?
1. The operating battery should be used in small amounts and multiple times. Reduce battery exposure time to air.
2. The completed batteries are transferred to the next process in a timely manner. Minimize the stagnation time of batteries in the manufacturing process.
78. What are the humidity requirements for drying rooms?
Relative humidity is below 6%.
79. What effect does the humidity of the drying room have on the performance of the battery?
Increased humidity increases the water absorption of the battery core, causing the battery capacity to decrease and the internal pressure to increase.
80. How to prevent moisture from entering the drying room?
Go in less, go out less, and open the door less often. The doors of the drying room cannot be opened at the same time.
81. Do you think the floor of a drying room can be wiped with water?
Can't.
82. What treatments need to be done before filling the battery with liquid?
Glued and vacuum baked.
83. Why does the battery need to be vacuum baked before filling?
Try to remove as much water and solvent as possible from the battery core.
84. Why should the battery be weighed before filling?
In order to accurately calculate the amount of liquid to be injected.
85. How to fill the battery?
Use a manual filling machine or an automatic filling machine for filling operations.
86. How to check whether the battery is filled with electrolyte?
Use vacuum suction to test. When using vacuum suction on the liquid filling port, if the electrolyte is drawn up, it means it is full, and if there is no electrolyte, it means it is not full.
87. What is the role of LiOF6 in the electrolyte?
Conductive electrolyte.
88. What is the concentration of LiPF6 in the electrolyte?
1mol/L
89. What is the role of solvent in electrolyte?
Dissolve electrolytes and ionize them.
90. What is the conductivity range of electrolyte?
8×10-3Ω-1
91. What is the effect of conductivity on battery operating current?
Conductivity affects the discharge rate, the internal resistance of the battery, and the voltage of the battery.
92. What factors affect the internal resistance of the battery?
The conductivity of the electrolyte, the material properties of the battery casing, the conductivity of the pole pieces and the cross-sectional area of the tab material. The quality of battery welding.
93. What factors affect battery capacity?
Characteristics and performance of positive and negative electrode materials as well as material type, model and amount of active material.
Correct ratio of positive and negative active materials.
The concentration and type of electrolyte.
production process.
94. How do you think the moisture in the battery can be controlled during the battery production process?
During the production process, the humidity of the environment is strictly controlled and the baking of the battery cells is strengthened to control the moisture content of the battery.
95. Can the resistance of the battery be measured with a meter when it is charged?
Can
96. What issues should the forming machine pay attention to when forming large-capacity batteries?
Pay attention to whether the total power of the battery exceeds the power of the forming machine.