The internal resistance of lithium-ion batteries will be scrapped
Lithium ion battery internal resistance is generally m ω as the unit, processing and manufacturing of more advanced lithium ion battery manufacturers, battery factory internal resistance in 0.3m ω ~ 30m ω, this depends on the size of the lithium cell to determine. The internal resistance of lithium-ion batteries will increase with use, so how much of the internal resistance of lithium-ion batteries will be scrapped? The exact number is not easy to say, but it can be determined by the phenomenon of the battery.
The heating degree of lithium ion battery is a good way to judge that lithium ion battery is close to scrap.
The conditions of the determination method: the same as the working condition of the new battery.
1, compared with the new battery, after use for a period of time, the new battery does not feel a clear change in temperature, the old battery slowly become hot, keep in a certain temperature range, and the use of time is shorter, indicating that the internal resistance increased, but not scrapped, can also continue to use;
2, under the same conditions of use, the battery temperature rises quickly, concurrent hot, soon used up, this shows that the lithium ion battery internal resistance increases to the extent of scrap.
Of course, this can not be generalized to say that the measured internal resistance of the battery is the value of the scrapped internal resistance, because the internal resistance of the battery will be different because of many factors. All this means is that lithium-ion batteries are nearing the end of their usefulness.
The internal resistance of lithium ion batteries can be divided into static internal resistance and working internal resistance. At the same time, the internal resistance varies with different temperatures in different environments. Broadly speaking, both activation polarization and concentration polarization can be understood as components of the internal resistance of lithium-ion batteries, or activation impedance and concentration impedance, in the same way as ohm resistance (IR). For lithium-ion batteries, the smaller the internal resistance, the better, preferably 0, but that's the ideal. The internal resistance of lithium-ion batteries will affect the standby time.
Factors affecting the internal resistance of lithium ion batteries
1. The influence of lithium ion battery manufacturing process on internal resistance
1) Too a little conductive agent in the positive electrode ingredients (poor conductivity between materials, because lithium cobalt itself is very poor)
2) too much binder for positive electrode ingredients (binder is a generally high polymer material, strong insulation performance)
3) anode ingredients too much binder (binder is a generally high polymer material, strong insulation performance)
4) Uneven dispersion of ingredients
5) The binder solvent is not complete when batching
6) The surface density of the coating is too large
7) Compaction density is too large, roller compaction
8) The positive pole ear is not welded firmly, and virtual welding occurs
9) The battery storage environment is unreasonable
2. Factors of lithium ion battery itself
Anode material, cathode material, lithium ion embedded, and unembedded degree of difficulty, determine the size of the material internal resistance, is a part of the concentration polarization resistance. The electrolyte, the rate of movement of lithium ions in the electrolyte, is affected by the conductivity of the electrolyte, is an important part of the electrochemical polarization resistance.
The diaphragm, the resistance of the diaphragm itself, forms part of the ohm resistance straight away, and its obstruction to the movement rate of lithium ions forms part of the electrochemical polarization resistance.
The collector resistance, the component connection resistance, is an important part of the ohmic internal resistance of lithium-ion batteries.
The level of technology, the production process of the pole piece, the coating is not average, the compaction density to how, the level of technology in the production process of these cells, will also cause a straight impact on the internal resistance of polarization.
The internal resistance of lithium ion batteries is too large
3, lithium ion battery materials affect the internal resistance
1) Lithium ion battery cathode material with high resistance (poor electrical conductivity, such as lithium iron phosphate)
2) influence of diaphragm material (diaphragm thickness, small porosity, small pore size)
3) Influence of electrolyte material (small conductivity, high viscosity)
4) Influence of positive PVDF material (large amount of high molecular weight)
5) Influence of positive conductive agent material (poor conductivity, high resistance)
6) Influence of positive and negative electrode materials (thin thickness, poor electrical conductivity, uneven thickness, poor material purity)
7) Copper foil, aluminum foil material poor conductivity or surface oxide
8) The internal contact resistance of the cover plate pole column is large
9) The negative material has high resistance
4. External factors
Temperature and ambient temperature are critical factors affecting the resistance of various lithium-ion batteries. In detail, it is due to the influence of temperature on the activity of electrochemical materials, which directly determines the speed of electrochemical reactions and the speed of ion movement.
The current or the demand of the load, on the one hand, current is directly related to the internal resistance of the polarization. The general trend is that the greater the current, the greater the internal polarization resistance. The thermal effect of electric current, on the other hand, affects the activity of electrochemical materials.
The simple detection method of internal resistance
Lithium ion battery to have no capacity and internal resistance to special internal resistance detector and capacity detector, 18650 internal resistance is generally between 20-65 milliohm, with a multimeter can only measure the voltage. 18650 Battery battery voltage internal resistance detector to test the battery voltage and internal resistance, with the charging cabinet to test the battery capacity.
18650 Battery intelligent internal resistance detector:
It is applied to the measured object 1KHz AC signal, by measuring its AC pressure drop to obtain its internal resistance. (It is different from the principle of multimeter resistance measurement, the value measured by it is milliohm level, and the value measured by multimeter is ohm level; And the multi-purpose meter can only measure the resistance value of the object without power supply, and the internal resistance meter can measure the resistance value of the object without power supply, but also can measure the resistance value of the object with power supply, so the two can not be equivalent) use the size of the internal resistance value to judge the deterioration state of the battery, (generally speaking) the smaller the resistance value of the battery performance is better. Therefore, the use of internal resistance to measure the battery is fast and reliable a good way.
MANLY Battery is a lithium battery manufacturer with 3 factories, mainly producing various square lithium batteries, cylindrical lithium batteries, such as 18650 lithium batteries, 26650 lithium batteries, 32650 lithium batteries, and various types of square batteries; also provide customers with mature, solar energy storage batteries, UAV model batteries, car emergency starter power, electric scooter batteries, twist car batteries, lamps and lanterns Battery, mobile power, flashlight battery, Bluetooth headset battery, UPS backup power and other series of mature design solutions, inquiry us atsales@manlybatteries.com.
