Battery Basic Principles and Basic Terminology
1. What is a Battery?
Batteries are energy conversion and storage devices that convert chemical or physical energy into electrical energy through a reaction. According to the different energy conversion of batteries, batteries can be divided into chemical batteries and physical batteries.
A chemical battery or chemical power supply 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, respectively, and a chemical substance that provides media conduction as the electrolyte, which when attached to some external carrier 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 and secondary batteries?
The main difference is the difference in the active substance, the active substance of the secondary battery is reversible, while the active substance of the primary battery is not reversible. The self-discharge of primary battery is much smaller than that of secondary battery, but the internal resistance is much larger than that of secondary battery, so the load capacity is lower, in addition, the mass specific capacity and volume specific capacity of primary battery are larger than that of general rechargeable battery.
3. What is the electrochemical principle of NiMH battery?
Nickel-metal hydride batteries use Ni oxide as the positive electrode, hydrogen storage metal as the negative electrode, and alkaline solution (mainly KOH) as the electrolyte, when charging nickel-metal hydride batteries:
Positive reaction: Ni(OH)2 + OH- → NiOOH + H2O-e-
Negative reaction: M+H2O +e-→ MH+ OH-
Nickel-metal hydride battery discharge:
Positive pole reaction: NiOOH + H2O + e- → Ni(OH)2 + OH-
Negative reaction: MH + OH- → M + H2O + e-
4. What is the electrochemical principle of lithium-ion battery?
The main component of the positive pole of lithium ion battery is LiCoO2, and the negative pole is mainly C. When charging, the
Anode 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 discharging.
5. What are the common standards for batteries?
Commonly used IEC standards for batteries: Nickel-metal hydride batteries are standardized as IEC61951-2:2003; lithium-ion batteries (lithium-ion battery anode materials technology and equipment seminar) industry is generally based on UL or national standards.
Batteries commonly used national standards: nickel-metal hydride batteries standard GB/T15100_1994, GB/T18288_2000; lithium-ion batteries standard GB/T10077_1998, YD/T998_1999, GB/T18287_2000.
In addition, the common standards for batteries also have the Japanese Industrial Standard JIS C standard on batteries.
IEC is the International Electrotechnical Commission (International Electrical Commission), is a worldwide standardization organization composed of national electrical commissions, which aims to promote the standardization of the world's electrical and electronic fields. the IEC standards are the standards developed by the International Electrotechnical Commission.
6. What is the main structure of NiMH battery?
The main components of nickel-metal hydride batteries are: positive electrode (nickel oxide), negative electrode (hydrogen storage alloy), electrolyte (mainly KOH), diaphragm paper, sealing ring, positive electrode cap, battery case and so on.
7. What is the main structure of lithium-ion battery?
The main components of lithium-ion batteries are: top and bottom caps, positive electrode (active substance is lithium cobalt oxide), diaphragm (a special composite membrane), negative electrode (active substance is carbon), organic electrolyte, battery shell (divided into two kinds of steel shells and aluminum shells) and so on.
8. What is the internal resistance of the battery?
It refers to the resistance of the current flowing through the inside of the battery when the battery is in operation. It consists of two parts: ohmic internal resistance and polarization internal resistance. A large internal resistance of the battery will lead to a lower discharge voltage and shorter discharge time. The size of internal resistance is mainly affected by the battery's material, manufacturing process, battery structure and other factors. It is an important parameter to measure the performance of the battery. Note: Generally, the charging state internal resistance is the standard. Measurement of the internal resistance of the battery needs to be measured with a special internal resistance meter, and can not be measured with a multimeter ohm gear.
9. What is the nominal voltage?
The nominal voltage of the battery refers to the voltage shown in the normal working process, the nominal voltage of secondary Ni-Cd-Ni-MH battery is 1.2V; the nominal voltage of secondary lithium battery is 3.6V.
10. What is open circuit voltage?
Open-circuit voltage is the potential difference between the positive and negative terminals of the battery when the battery is not in working condition, i.e., when there is no current flowing in the circuit. Working voltage, also known as terminal voltage, refers to the battery in the working state, that is, when there is current in the circuit out of the battery potential difference between the positive and negative terminals.
11. What is the capacity of the battery?
The capacity of the battery has a rated capacity and actual capacity. The rated capacity of the battery refers to the design and manufacture of batteries, or to ensure that the battery in a certain discharge conditions, the minimum amount of power should be discharged, IEC standards provide for nickel-cadmium and nickel-metal hydride batteries at 20 ℃ ± 5 ℃ environment, to 0.1C charge 16 hours after 0.2C discharged to 1.0V when the amount of power discharged to the battery's rated capacity, expressed in C5. For lithium-ion batteries, it is stipulated that the rated capacity is the amount of electricity discharged when the battery is charged for 3 hours at room temperature under the charging conditions of constant current (1C)-constant voltage (4.2V) control and then discharged to 2.75V at 0.2C. The actual capacity of the battery refers to the amount of electricity discharged by the battery under certain discharging conditions, which is mainly affected by the discharging multiplication rate and the temperature (therefore, the capacity should be specified as the actual capacity of the battery. Strictly speaking, the battery capacity should specify the charging and discharging conditions). Battery capacity units are Ah, mAh (1Ah = 1000mAh).
12. What is the discharge residual capacity of the battery?
When the rechargeable battery with high current (such as 1C or more) discharge, due to the current over the Ambassador's internal diffusion rate of the existence of the "bottleneck effect", resulting in the capacity of the battery in the capacity can not be fully discharged when the terminal voltage has reached, and then use a small current, such as 0.2C can continue to discharge until 1.0V/branch (nickel-cadmium and nickel-metal hydride batteries) and 3.0V/branch (lithium batteries). The capacity discharged at 1.0V/battery (Ni-Cd and Ni-MH batteries) and 3.0V/battery (Li-ion batteries) is called residual capacity.
13. What is the discharge platform?
The discharge platform of NiMH rechargeable battery usually refers to the voltage range where the working voltage of the battery is relatively smooth when the battery is discharged under a certain discharge regime, and its value is related to the discharge current, and the higher the current, the lower its value. Lithium-ion battery (lithium-ion battery anode materials technology and equipment seminar) discharge platform is generally a constant voltage charging to the voltage of 4.2V and the current is less than 0.01C to stop charging, and then set aside for 10 minutes in any rate of discharge current under the discharge to 3.6V when the discharge time. It is an important criterion to measure the good and bad of the battery.
