Lithium ion capacitor module

Product introduction:

         The utility model relates to an energy storage device, in particular to a lithium ion capacitor module. Energy storage devices mainly include lithium ion batteries (LIB) and electric double layer capacitors (EDLC, that is, supercapacitors), which have been widely used. Lithium ion batteries have the advantages of high energy density, short service life and low power density. Super capacitors have the advantages of high output power and long cycle life, and low energy density. Lithium ion capacitor (LIC) adopts a mixed structure of lithium ion battery and electric double-layer capacitor, with active carbon as positive electrode and graphite as negative electrode. It has the characteristics of high power density of supercapacitor (its power density is much higher than that of lead-acid battery), long life and high energy density of lithium-ion battery.

Advantages of lithium ion capacitor module: 

          the required capacity and voltage are not satisfied by a single lithium ion capacitor cell, so lithium ion capacitor cells must be assembled into modules in series or parallel. As the lithium ion capacitor will generate a lot of heat during high-power charging and discharging, the whole module, especially the lithium ion capacitor core, should fully consider the problem of heat dissipation in module design. Because if the heat is not dissipated in time, a large amount of heat will damage the internal structure of the electric core, thus making the consistency of each lithium ion capacitor electric core in the module worse, which may seriously lead to short circuit of the electric core and other phenomena, thus greatly reducing the service life of the entire module.

Purpose/application field:

Intelligent three meter

It has very high voltage retention capability. After being placed at 25 ° C for 3 months, the voltage drop is less than 5%; Operation safety and reliability in a wide temperature range (- 40 ° C~65 ° C). The lithium ion capacitor module can be used in the smart three meter power supply market (water meter, electricity meter, gas meter). It mainly adopts the scheme of connecting two external dry batteries+super capacitor power supply. The power compensation and management of intelligent equipment are particularly important, with the help of the fast response, super long life, high safety and other characteristics of the lithium ion capacitor or ultra fast charging battery.

Test method:

1. Electrostatic capacity tester

(1) Test principle

The electrostatic capacity of supercapacitor is measured by the method of constant current discharge of the capacitor and calculated according to the formula. C=It (U1-U2), where: C - electrostatic capacity, F;

I - Constant discharge current, A; U1, U2 - voltage, V; Discharge time required from t-U1 to U2, S

(2) Test procedure

Charge the capacitor with a current of 100A until the capacitor is charged to the working voltage and the voltage is constant for 10 seconds, then discharge the capacitor with a current of 100A, taking U1 as 1.2VU2 as 1.0V, record the discharge time within the voltage range, the total circulating electrostatic capacity, and take the average

2. Storage energy

(1) Testing

The energy test of super capacitor is carried out by discharging the capacitor to 1/2 of the working voltage at constant power within the voltage range given by the capacitor. The output energy W of capacitor is obtained from the relationship between constant discharge power P and discharge time T, that is, W=P. T

(2) Test procedure

Charge the capacitor to the working voltage with a constant current of 100A, and then keep it constant until the charging current drops to the specified current (traction type 10A, starting type 1A). After 5 seconds of standstill, discharge the capacitor to 1/2 of the working voltage with a constant power, record the discharge time and calculate the value. Cycle 3 measurements and take the average value

3. Equivalent series resistance test (DC)

(1) Test principle

The internal resistance of the capacitor is measured according to the sudden change of voltage within 10ms after the capacitor disconnects the constant current charging circuit. In the formula: R-internal resistance of capacitor; U0 - Voltage before capacitor cut-off charging; Ui - Voltage within 10 ms after switching off charging; I - Cut off the current before charging.

(2) Measuring process

Charge the capacitor with a constant current of 100A, disconnect the charging circuit when 80% of the charging working voltage is reached, use a sampling machine to record the voltage change within 10 ms after the capacitor is powered off, calculate the internal resistance, repeat for 3 times, and take the average value.

4. Leakage current test

After the capacitor is charged to the rated voltage with a constant current of 100A, the capacitor is charged at this voltage for 30min at a constant voltage, and then it is left open for 72h. In the first three hours, record the voltage value every minute, and in the remaining time, record the voltage value every ten minutes.

Calculate the self discharge energy loss, SDLF=1 - (V/VW) 2, and the calculation time points are respectively 0.5,1,8,24,36,72h

Note: The voltage tester must have high input impedance to minimize the sound of the film.

Precautions:

Super capacitors cannot be used in the following states:

1) Temperature above nominal temperature

When the capacitor temperature exceeds the nominal temperature, the electrolyte will decompose, and the capacitor will generate heat, reduce capacity, increase internal resistance, and shorten service life.

2) Voltage exceeding rated voltage

When the capacitor voltage exceeds the nominal voltage, the electrolyte will decompose, and the capacitor will generate heat, reduce capacity, increase internal resistance and shorten life. Therefore, reducing the service voltage can improve the service life.

3) Loading of reverse voltage or AC voltage

1. Influence of ambient temperature on supercapacitor

The service life of supercapacitor is affected by the service temperature. Generally, if the service temperature is increased by 10 ℃, the service life of supercapacitor will be shortened by half. Please try to use it in a low temperature environment lower than the service temperature. If it is used beyond the service temperature, it may cause sharp deterioration and damage of the characteristics. The use temperature of the super capacitor should not only confirm the ambient temperature and internal temperature of the equipment, but also confirm the radiation heat of the heater (power transistor, resistor, etc.) in the equipment, and the self heating temperature caused by ripple current. In addition, do not install the heater near the supercapacitor.

2. Please use the capacitor correctly according to the positive and negative pole marks.

3. Please avoid using super capacitors in the following environments.

a) The environment is directly splashed with water, salt water and oil, or is in the state of condensation and full of gas like oil or salt.

b) An environment full of harmful gases (hydrogen sulfide, sulfurous acid, chlorine, ammonia, bromine, methyl bromide, etc.).

c) Environment splashed with acidic and alkaline solvents.

d) Direct sunlight or dusty environment.

e) An environment subject to excessive vibration and shock.

4. Avoid overheating the capacitor during welding (for 1.6mm printed circuit board, the welding temperature shall be 260 ℃, and the time shall not exceed 5s).

5. Please avoid conducting circuit wiring between the outgoing poles of the super capacitor or between the solder joints of the connecting plate.

6. Overvoltage, exceeding the operating temperature range and other conditions beyond the rated conditions may cause the pressure valve to act and the electrolyte will be ejected. Therefore, please adopt the design method that has considered the possible occurrence of this abnormal condition.

7. During fast charging and discharging, voltage drop (also called IR drop) caused by internal impedance will be generated at the beginning of charging and discharging. Therefore, please adopt the design method that has considered the voltage change range.

8. If the terminals of power type high-capacity products (products above 10F) are short circuited during charging, hundreds of amperes of current will flow through, which is dangerous. Do not install or remove the battery in the charged state.

9. Do not put the capacitor into the dissolved solder, only stick solder on the guide pin of the capacitor. Do not let the welding rod contact the capacitor heat shrink tube.

10. Do not twist or tilt the capacitor forcibly after installation.

11. When the supercapacitor is used in series, there is a problem of voltage balance between individual capacitors

matters needing attention:

1、 Use

1. The operating temperature of lithium ion capacitor should not exceed the upper or lower limit of rated temperature (- 20 ℃~+55 ℃)

2. Lithium ion capacitors shall be used at nominal voltage. In order to prolong the service life of the product, we recommend that the monomer be used within the range of "rated voltage" (2.5v-3.8v).

3. Before using the lithium ion capacitor, please acknowledge the polarity and prevent reverse connection.

4. The external ambient temperature has a weight impact on the life of the lithium ion capacitor. Please keep away from heat sources.

5. Do not touch water, oil, acid or alkali directly.

6. Do not knead, nail or disassemble the lithium ion capacitor.

7. Do not discard the lithium ion capacitor at will, and dispose it according to the national environmental protection standards.

2、 Storage

1. During transportation, the lithium ion capacitor shall be handled with care to avoid violent vibration, kneading, rain and chemical corrosion.

2. The lithium ion capacitor shall not be located in a place with a relative humidity of more than 85% or containing toxic gas. In such an environment, the lead and shell are prone to moisture and corrosion, which may cause the circuit break of the ultrafast charging battery.

3. If the lithium ion capacitor needs to be stored for a long time, please store it in a place with excellent ventilation and temperature of - 40~35 ℃ and relative humidity below 50%.