Lithium-ion battery internal resistance composition and internal resistance influencing factors

The internal resistance of the lithium-ion battery constitutes the internal resistance of the battery including ohmic resistance and polarization resistance. Under the condition of constant temperature, the ohmic resistance is basically stable, and the polarization resistance will change with the factors that affect the polarization level. The ohmic resistance is mainly composed of the contact resistance of various parts such as electrode material, electrolyte, diaphragm resistance, current collector, and tab connection. It is related to the size, structure, and connection mode of the battery. Polarization resistance, the resistance that appears at the moment when current is applied, is the sum of various trends in the battery that prevent charged ions from reaching their destination. Polarization resistance can be divided into two parts: electrochemical polarization and concentration polarization. Electrochemical polarization is caused by the fact that the speed of the electrochemical reaction in the electrolyte cannot reach the moving speed of electrons; the concentration polarization is caused by the speed at which lithium is inserted and removed from the positive and negative materials and moves in the material less than the speed at which lithium is assembled to the electrode. . Influencing factors of the internal resistance of lithium-ion batteries 1 External factors temperature, ambient temperature is an important factor affecting various resistances, specific to lithium-ion batteries, because temperature affects the activity of electrochemical materials, directly determines the speed of electrochemical reaction and ion movement speed. Current or load demand, on the one hand, the magnitude of the current is directly related to the internal polarization resistance. The general trend is that the greater the current, the greater the internal polarization resistance. On the other hand, the thermal effect of current has an impact on the activity of electrochemical materials. 2 The battery's own factors The degree of difficulty of the positive electrode material, negative electrode material, and lithium insertion and extraction determines the internal resistance of the material, which is part of the concentration polarization resistance. In the electrolyte, the movement rate of lithium in the electrolyte is affected by the conductivity of the electrolyte and is an important part of the electrochemical polarization resistance. The diaphragm, the diaphragm's own resistance, directly constitutes a part of the ohmic internal resistance, and at the same time it hinders the lithium movement rate, and forms a part of the electrochemical polarization resistance. Current collector resistance, component connection resistance, is an important part of the battery's ohmic internal resistance. The level of craftsmanship, the production process of the pole piece, whether the coating is uniform, and the compaction density, the level of craftsmanship in the production process of these batteries will also have a direct impact on the polarization internal resistance. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What are the basic detection methods for 18650 lithium ion batteries