Welcome to our comprehensive guide on battery technology! In today’s rapidly advancing world, understanding the intricacies of battery technology is essential for navigating the myriad of battery-powered devices and applications. Whether you’re a tech enthusiast, a professional in the field, or simply curious about the science behind the devices we use daily, this article aims to clarify the most commonly asked questions about battery technology. We delve into the top 20 FAQs to equip you with the knowledge needed to make informed decisions.
1. What is a battery?
Batteries are a device for energy conversion and storage. They convert chemical energy or physical energy into electrical energy through reactions. According to the difference in energy conversion by batteries, batteries can be divided into chemical and physical batteries.
A chemical battery or chemical power source is a device that converts chemical energy into electrical energy. It consists of two electrochemically active electrodes of different compositions, forming the positive and negative electrodes. The battery uses a chemical substance that can provide media conduction as the electrolyte. When connected to an external carrier, it provides electrical energy by converting its internal chemical energy.
A physical battery is a device that converts physical energy into electrical energy.
2. What are the differences between primary batteries and secondary batteries?
The main difference between primary and secondary batteries is the difference in active materials. The active material of the secondary battery is reversible. The active material of a primary battery is not reversible. The self-discharge of primary batteries is much smaller than that of secondary batteries. Still, the internal resistance is much greater than that of secondary batteries, so the load capacity is lower. In addition, primary batteries’ mass and volume specific capacity are larger than general rechargeable batteries.
3. What is the electrochemical principle of nickel-metal hydride batteries?
Nickel metal hydride batteries use Ni oxide as the positive electrode, hydrogen storage metal as the negative electrode, and alkali solution (mainly KOH) as the electrolyte.
When charging NiMH batteries:
- Positive electrode reaction: Ni(OH)2 + OH- → NiOOH + H2O–e-
- Negative reaction: M+H2O +e-→ MH+ OH-
When nickel metal hydride batteries are discharged:
- Positive electrode reaction: NiOOH + H2O+e- → Ni(OH)2 + OH-
- Negative reaction: MH+OH- →M+H2O+e-
4. What is the electrochemical principle of lithium-ion batteries?
The main component of the positive electrode of lithium-ion batteries is LiCoO2, and the negative electrode is mainly C (carbon).
When charging a lithium-ion battery:
- Positive electrode reaction: LiCoO2 → Li1-xCoO2 + xLi+ + xe-
- Negative reaction: C + xLi+ + xe- → CLix
- Total battery reaction: LiCoO2 + C → Li1-xCoO2 + CLix
The reverse reaction of the above reaction occurs when a lithium-ion battery is discharged.
5. What are the commonly used standards for batteries?
Batteries commonly use IEC standards. IEC, the International Electrical Commission, is a worldwide standardization organization composed of electrotechnical committees from various countries. Its purpose is to promote standardization in the world’s electrical and electronic fields. IEC standards are standards developed by the International Electrotechnical Commission.
The standard for nickel-metal hydride batteries is IEC61951-2:2003;
The lithium-ion battery industry generally follows UL or national standards;
Commonly used national standards for batteries in China:
Standards for nickel-metal hydride batteries: GB/T15100_1994, GB/T18288_2000;
Lithium battery standards: GB/T10077_1998, YD/T998_1999, GB/T18287_2000.
In addition, the commonly used standards for batteries also include the Japanese Industrial Standard JIS.
6. What are the main structural components of nickel-metal hydride batteries?
The main components of nickel-metal hydride batteries are positive electrode sheet (nickel oxide), negative electrode sheet (hydrogen storage alloy), electrolyte (mainly KOH), diaphragm paper, sealing ring, positive electrode cap, battery shell, etc.
7. What are the main structural components of lithium-ion batteries?
The main components of a lithium-ion battery are the upper and lower battery covers, positive electrode sheet (the active material is lithium cobalt oxide), separator (a special composite film), the negative electrode (the active material is carbon), organic electrolyte, and battery case (divided into steel shell and aluminum shell), etc.
8. What is battery internal resistance?
The internal resistance of the battery refers to the resistance to current flowing through the interior of the battery when the battery is working. The battery’s internal resistance is composed of 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 battery’s internal resistance is mainly affected by the battery material, manufacturing process, battery structure, and other factors. Battery is an important parameter to measure battery performance. The battery’s internal resistance is generally based on the internal resistance in the charged state. To measure the battery’s internal resistance, you need to use a special internal resistance meter rather than the ohm range of a multimeter.
9. What is the nominal voltage?
The battery’s nominal voltage refers to the voltage displayed during normal operation. The nominal voltage of the secondary nickel-cadmium nickel-metal hydride battery is 1.2V. The nominal voltage of a secondary lithium battery is 3.6V.
10. What is open circuit voltage?
Open circuit voltage 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. Working voltage, also called terminal voltage, 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.
11. What is battery capacity?
The capacity of the battery is divided into rated capacity and actual capacity.
Battery rated capacity:
The battery’s rated capacity 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.
IEC standards stipulate that the power released when nickel-cadmium and nickel-metal hydride batteries are charged at 0.1C for 16 hours and discharged to 1.0V at 0.2C in an environment of 20℃±5℃ is the battery’s rated capacity.
For lithium-ion batteries, it is stipulated that the battery should be charged for 3 hours under normal temperature, constant current (1C)-constant voltage (4.2V) controlled charging conditions. Then it discharged at 0.2C to 2.75V as its rated capacity.
Battery actual capacity
The capacity of the battery refers to the amount of electricity released by the battery under certain discharge conditions. The battery’s actual capacity is mainly affected by the discharge rate and temperature (so strictly speaking, the battery capacity should specify the charging and discharging conditions). The battery capacity units are Ah and mAh (1Ah=1000mAh).
12. What is the residual capacity of the battery after discharge?
When a rechargeable battery is discharged with a large current (such as 1C or above), due to the “bottleneck effect” of the internal diffusion rate caused by the excessive current, the battery reaches the end voltage before the capacity is fully discharged. It can continue to discharge with a small current, such as 0.2C until the capacity released when it reaches 1.0V (nickel-cadmium and nickel-metal hydride batteries) and 3.0V (lithium batteries) is called residual capacity.
13. What is a battery discharge platform?
The discharge platform of nickel-metal hydride rechargeable batteries usually refers to the voltage range in which the battery’s operating voltage is relatively stable when discharged under a certain discharge system. Its value is related to the discharge current. The greater the current, the lower its value.
The discharge platform of lithium-ion batteries generally has a constant voltage charge until the voltage is 4.2V, and the charging is stopped when the current is less than 0.01C. Then, leave it for 10 minutes and discharge to 3.6V at any discharge current. The battery discharge platform is an important criterion for measuring the quality of the battery.
14. What are the standard charging and discharging of nickel-metal hydride batteries?
The IEC international standard stipulates that the standard charging and discharging of nickel-metal hydride batteries is: first discharge the battery to 1.0V at 0.2C, then charge it at 0.1C for 16 hours, leave it for 1 hour, and discharge it to 1.0V at 0.2C, which is the battery standard. Discharge.
15. What is pulse charging? What impact does it have on battery performance?
Pulse charging generally adopts the method of charging and discharging, that is, charging for 5 seconds and then discharging for 1 second. This way, most of the oxygen generated during the charging process will be reduced to electrolytes under the discharge pulse. Not only does it limit the amount of vaporization of the electrolyte inside the battery, but also, for old batteries that have been severely polarized, after using this charging method to charge and discharge 5-10 times, they will gradually recover or approach the original battery capacity.
16. What is battery trickle charging?
Trickle charging is used to compensate for the loss of capacity due to self-discharge after the battery is fully charged. Generally, pulse current charging is used to achieve the above purpose.
17. What is battery charging efficiency?
Charging efficiency refers to the degree to which the electrical energy consumed by a battery during charging is converted into chemical energy that the battery can save. Charging efficiency is mainly affected by the battery process and the working environment temperature. Generally, the higher the ambient temperature, the lower the charging efficiency.
18. What is battery discharge efficiency?
Discharge efficiency refers to the ratio of electricity released to the rated capacity when discharging to the end voltage under certain discharge conditions. Battery discharge efficiency is mainly affected by discharge rate, ambient temperature, and internal resistance. Generally speaking, the higher the battery discharge rate, the lower the discharge efficiency. The lower the temperature, the lower the discharge efficiency.
19. What is the power output of the battery?
The output power of a battery refers to the ability to output energy per unit of time. It is calculated based on the discharge current and voltage, P=U*I, and the unit is watts.
The smaller the battery’s internal resistance, the higher the output power. The battery’s internal resistance should be smaller than the internal resistance of the electrical appliance. Otherwise, the power consumed by the battery itself will be greater than that consumed by the electrical appliance. This is uneconomical and may damage the battery.
20. What is battery internal pressure?
Battery internal pressure refers to the internal air pressure of the battery, which is caused by the gas generated by the sealed battery during the charging and discharging process. The battery’s internal pressure is mainly affected by battery materials, manufacturing processes, battery structure, and other factors. The main reason is that the gas generated by the decomposition of moisture and organic solutions inside the battery accumulates in the battery. Generally, the battery’s internal pressure is maintained at a normal level. In the case of overcharge or over discharge, the battery’s internal pressure may increase.
For example, when the battery is overcharged, the positive electrode: 4OH- – 4e → 2H2O + O2↑; ①
The generated oxygen reacts with the hydrogen precipitated on the negative electrode to form water 2H2 + O2 → 2H2O ②
Suppose the speed of reaction ② is lower than the speed of reaction ①. In that case, the oxygen produced will not be consumed in time, which will cause the internal pressure of the battery to increase.
21. Summary
In conclusion, this article aims to demystify battery technology’s complexities by addressing the top 20 frequently asked questions in the field. By exploring these FAQs, we hope this guide has deepened your understanding and appreciation of battery technology.
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