Analysis on the factors affecting the internal resistance of lithium batteries

Why do lithium batteries have internal resistance? The internal resistance, static internal resistance and working internal resistance of lithium batteries are often different. In different environments, the internal resistance also changes with changes in temperature. What are the factors that affect the internal resistance of lithium batteries? 1. Why does the lithium battery have internal resistance? As shown in the figure, it is a physical model of the charging and discharging process of lithium batteries. The blue arrow indicates charging and the red arrow indicates discharging. The blue and green grid structures are positive data, and the black ones are negative data. The current mainstream lithium batteries are generally named according to the data type of the positive electrode. Lithium iron phosphate and lithium manganese phosphate are the data types of the positive electrode; the negative electrode graphite material; the positive electrode collecting fluid aluminum foil, and the negative electrode collecting fluid copper foil. Let us take discharge as an example to describe the physical process of lithium battery discharge. After the external load is connected, a current path is formed outside the battery body. Due to the potential difference between the positive electrode and the negative electrode, the primary electron flow near the negative electrode and the external lead move toward the positive electrode. The concentration of lithium ions around the negative electrode has been added. Electrons from the negative electrode enter the positive electrode through an external circuit, combine with lithium ions close to the positive electrode, and embed data on the positive electrode. The concentration of lithium ions near the positive electrode decreases. The difference between the positive and negative concentrations of lithium ions. This completes the first step of the battery discharge process. As lithium ions rise from the negative electrode in the ion concentration difference, vacancies appear near the negative electrode. Lithium ions in the negative data are separated from the negative electrode and enter the electrolyte. A large amount of lithium ions pass through the diaphragm from the electrolyte and move toward the positive electrode. Together with lithium ions, electrons originally exist in the form of bonds with lithium ions, and reach the positive electrode through an external circuit. The battery starts to discharge according to the load. Charging is the opposite process of discharging. Use the same three stages of digging, moving and burying. However, the driving force for the development of this process comes from the charger, and the direction of movement of the ions is from the positive electrode to the negative electrode. I won't go into details here. 2. The composition of the internal resistance of the lithium battery knows the operation process of the lithium battery, and then knows the process of its blocking elements, and then constitutes the internal resistance of the lithium battery. The internal resistance of the battery is composed of ohmic resistance and polarization resistance. When the temperature is stable, the ohmic resistance is stable, and the polarization resistance changes with the factors that affect the polarization level. The ohmic resistance is mainly composed of electrode data, electrolyte, diaphragm resistance and contact resistance, such as the connection between the collecting liquid and the tab. It is related to the size, structure and connection mode of the battery. Polarization resistance appears when current is loaded and is the sum of various trends in the battery that prevent charged ions from reaching their destination. Polarization resistance can be divided into electrochemical polarization and concentration polarization. When the electrochemical reaction speed in the electrolyte cannot reach the electron movement speed, electrochemical polarization is formed. When lithium ions are embedded in the positive and negative data and enter the electrode at a slower speed than lithium ions, concentration polarization will be formed. 3. The influencing factors of the internal resistance of the lithium battery can be derived from the above process. 3.1 The additional element temperature and ambient temperature are important influencing factors of various resistances, especially lithium batteries, because temperature affects the activity of electrochemical data and directly determines the speed of electrochemical reactions and ion movement. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: What are the differences between lithium batteries and storage batteries