Battery basic principles and basic terms

1. What is a battery?

battery(Batteries) is a device for energy conversion and storage that converts chemical or physical energy into electrical energy through a reaction. The battery can be divided into a chemical battery and a physical battery depending on the energy converted from the battery.

A chemical battery or chemical power source is a device that converts chemical energy into electrical energy. It consists of two different compositions of electrochemically active electrodes that make up the positive and negative electrodes. A chemical that provides media conduction acts as an electrolyte. When connected to an external carrier, it provides electrical energy by converting its internal chemical energy. .

2. What is the difference between a primary battery and a secondary battery?

The main difference is the difference in active substances, the active material of the secondary battery is reversible, and the active material of the primary battery is not reversible. The self-discharge of the primary battery is much smaller than that of the secondary battery, but the internal resistance is much larger than that of the secondary battery, so the load capacity is low. In addition, the mass specific capacity and the volume specific capacity of the primary battery are larger than those of the general rechargeable battery.

3. What is the electrochemical principle of NiMH batteries?

Nickel-metal hydride batteryNi oxide is used as the positive electrode, hydrogen storage metal is used as the negative electrode, and alkali solution (mainly KOH) is used as the electrolyte. When the nickel-hydrogen battery is charged:

Positive reaction:Ni(OH)2 + OH- → NiOOH + H2O–e-

Negative reaction:M+H2O +e-→ MH+ OH-

When the NiMH battery is discharged:

Positive reaction:NiOOH + H2O + e- → Ni(OH)2 + OH-

Negative reaction:MH+ OH- →M+H2O +e-

4. What is the electrochemical principle of a lithium ion battery?

The main component of the positive electrode of lithium ion battery isLiCoO2, the negative electrode is mainly C, when charging,

Positive reaction: LiCoO2 → Li1-xCoO2 + xLi+ + xe-

Negative reaction: C + xLi+ + xe- → CLix

Total battery response: LiCoO2 + C → Li1-xCoO2 + CLix

The reverse reaction of the above reaction occurs upon discharge.

5. What are the commonly used standards for batteries?

Battery commonly usedIEC standard: The standard for nickel-metal hydride batteries is IEC61951-2:2003; the lithium-ion battery industry is generally based on UL or national standards.

National standard for batteries: The standard for nickel-metal hydride batteries isGB/T15100_1994, GB/T18288_2000; The standard for lithium batteries is GB/T10077_1998, YD/T998_1999, GB/T18287_2000.

In addition, the battery standard is also Japanese industrial standard.JIS C Standard for batteries.

The IEC, the International Electrical Commission, is a worldwide standardization organization composed of national electrotechnical committees, which aims to promote standardization in the world of electrical and electronic fields. The IEC standard is a standard established by the International Electrotechnical Commission.

6. What is the main structural composition of NiMH batteries?

The main components of nickel-metal hydride batteries are: positive electrode sheets (nickel oxide), negative electrode sheets (hydrogen storage alloys), and electrolytes (mainlyKOH), separator paper, sealing ring, positive cap, battery case, etc.

7. What is the main structural composition of a lithium ion battery?

The main components of lithium-ion battery are: battery upper and lower cover, positive electrode sheet (active material is lithium cobalt oxide), separator (a special composite film), negative electrode (active material is carbon), organic electrolyte, battery case (divided into Steel shell and aluminum shell) and so on.

8. What is the internal resistance of the battery?

It refers to the resistance that current flows through the inside of the battery while the battery is working. It consists of two parts: ohmic internal resistance and polarization internal resistance. The large internal resistance of the battery will cause the battery discharge operating voltage to decrease and the discharge time to be shortened. The internal resistance is mainly affected by factors such as the material of the battery, the manufacturing process, and the structure of the battery. It is an important parameter to measure battery performance. Note: Generally, the internal resistance of the charge state is the standard. Measuring the internal resistance of the battery requires a special internal resistance meter and cannot be measured with a multimeter ohmmeter.

9. What is the nominal voltage?

The nominal voltage of a battery refers to the voltage that is exhibited during normal operation. The secondary nickel-cadmium nickel-hydrogen battery has a nominal voltage of1.2V; the nominal voltage of the secondary lithium battery is 3.6V.

10. What is the open circuit voltage?

The open circuit voltage refers to the potential difference between the positive and negative terminals of the battery when the battery is not in operation, that is, when no current flows through the circuit. The working voltage, also called the terminal voltage, refers to the potential difference between the positive and negative terminals of the battery when the battery is in operation, that is, when there is current in the circuit.

11. 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 means that the battery should be designed or manufactured to ensure that the battery should emit a minimum amount of electricity under certain discharge conditions.The IEC standard stipulates that the amount of electricity discharged by a nickel-cadmium and nickel-hydrogen battery at 20 °C ± 5 °C after being charged at 0.1 C for 16 hours and then discharged at 0.2 C to 1.0 V is the rated capacity of the battery, expressed as C5. For a lithium-ion battery, it is specified to be charged for 3 hours under normal temperature, constant current (1C)-constant voltage (4.2V) controlled charging conditions, and then discharged at 0.2C to 2.75V for its rated capacity. The actual capacity of the battery refers to the actual amount of electricity discharged by the battery under certain discharge conditions, which is mainly affected by the discharge rate and temperature (so strictly speaking, the battery capacity should indicate the charge and discharge conditions). The unit of battery capacity is Ah, mAh (1Ah = 1000mAh).

12. What is the discharge residual capacity of the battery?

When using large currents for rechargeable batteries (eg1C or above) When discharging, the "bottleneck effect" of the internal diffusion rate due to excessive current causes the battery to reach the end voltage when the capacity is not fully discharged, and then continue to discharge with a small current such as 0.2C until 1.0V. The capacity released when the / branch (nickel cadmium and nickel hydrogen battery) and 3.0V / branch (lithium battery) are called residual capacity.

13. What is a discharge platform?

The discharge platform of a nickel-hydrogen rechargeable battery generally refers to a voltage range in which the operating voltage of the battery is relatively stable when the battery is discharged under a certain discharge system, and the value thereof is related to the discharge current. The larger the current, the lower the value. The discharge platform of a lithium ion battery is generally a constant voltage charge to a voltage ofWhen 4.2V and the current is less than 0.01C, the battery is stopped, and then left for 10 minutes, and discharged at a discharge current of any rate to a discharge time of 3.6V. It is an important criterion for measuring the quality of a battery.