How is the internal resistance produced?
October 15, 2018
The internal resistance of the battery includes ohmic resistance and polarization resistance. Under constant temperature conditions, the ohmic resistance is substantially constant, and the polarization resistance varies with factors affecting the polarization level.
The ohmic resistance is mainly composed of the contact resistance of each part of the electrode material, the electrolyte, the diaphragm resistance, the current collector, and the connection of the tabs, and is related to the size, structure, and connection mode of the battery.
The internal impedance is affected by the physical properties of the electrolyte, and the smaller the particle size of the electrolyte material, the lower the impedance. The grain size is controlled by the battery manufacturer during the processing of the electrolyte material powder.
The helical structure of the electrodes is typically used to maximize surface area, thereby reducing internal impedance. This approach reduces heat generation and allows for faster charge and discharge rates.
At low temperatures, the material inside the battery is poorly active, so it may be very inefficient at low temperatures. As the temperature increases, the battery efficiency increases and the internal reaction speed increases. A bad effect is that the battery self-discharge also increases.
Since most of the active chemicals have been embedded in the electrode at the end of the discharge to form a stable situation, the free active material is less and less. Therefore, the internal resistance of the battery also increases significantly at the end of the discharge, which is also the main reason for the rapid decline of the battery voltage at the end of the discharge. the reason.