Briefly describe the working principle and structural composition of lithium batteries

Briefly describe the working principle of lithium batteries. Many people misunderstand that lithium batteries contain metallic lithium. In fact, it is just a lithium ion compound. During charging, the positive electrode decomposes lithium ions, and the negative electrode of the battery is carbon. The process of inserting and releasing lithium ions from the positive electrode compound is the process of battery charge and discharge. Generally, people use embedding to represent charging, and discharger to represent discharging. The process of inserting and pulling out lithium ions back and forth between the positive electrode and the negative electrode is the process of charging and discharging. Therefore, lithium batteries are also called rocking chair batteries. Lithium battery charging: The charging process is the process of the appearance and movement of lithium ions. A large amount of lithium ions appear in the positive electrode compound of the battery. After passing through the electrolyte, the lithium ions move from the positive electrode to the negative electrode. The positive electrode of a lithium battery is made of carbon material. The lithium ions reaching the negative electrode will be inserted into the pores of the carbon material. The carbon material can hold more lithium ions. The more energy the battery can hold, the more it is called capacity. (mAh). Lithium battery discharge: The discharge process is opposite to the charging process. Lithium ions return to the positive electrode from the carbon material pores of the negative electrode. The more lithium ions return to the positive electrode, the more the battery is used and the less there is left. The electrolyte of a lithium battery is the interaction between the electrolyte and the electrode material in the battery. The decomposition reaction exists in the electrolyte itself, which participates in almost all reaction processes that occur in the battery. At present, most of the electrolytes contained in lithium batteries are organic systems. In the case of overcharge, overdischarge, short circuit, heat shock, etc., the temperature of the battery rises rapidly, and the electrolyte is generally flammable, which often causes the battery to catch fire or even explode. At present, the biggest obstacle to the commercialization of high-capacity dynamic lithium batteries is safety. Therefore, choosing an appropriate electrolyte system is also one of the keys to obtaining high energy, long cycle life and safety performance for lithium secondary batteries. The electrolyte is an important part of the battery, it can transport ions and conduct current between the positive and negative electrodes. Lithium battery electrolytes can be divided into liquid electrolytes, solid electrolytes and molten salt electrolytes according to their phases. Starting from the actual mass transfer requirements of lithium batteries, the electrolyte must meet the following basic requirements: (1) Ionic conductivity: The electrolyte does not have electronic conductivity, but must have good ionic conductivity. In the general temperature range, the conductivity of the electrolyte is between 1×10-3~2×10-3s/cm. (2) Ion migration number: The charge migration in the battery depends on ion migration. A higher ion migration number can reduce the concentration polarization of the electrode reaction, so that the battery has a higher energy density and power density. The ideal migration number of lithium ions should be as close to 1 as possible. (3) Stability: When the electrolyte is in direct contact with the electrode, try to prevent side reactions from occurring, which requires the electrolyte to have a certain degree of chemical stability and thermal stability. (4) Mechanical strength: The electrolyte must have high enough mechanical strength to meet the mass processing and packaging process of batteries. Li et al. used trimethyl phosphate (TMP) as a high-voltage electrolyte additive, and Li1.2Mn0.54Ni0.13Co0.13O2 as the positive electrode of the battery. The results showed that adding 1% TMP to the electrolyte can significantly improve the battery’s performance. Performance and cycle performance. In order to prevent the leakage, flammability, explosion and other safety problems of traditional lithium batteries, the electrolyte system of lithium secondary batteries has been developed to solid state. Solid electrolytes, also known as fast ion conductors, require high ionic conductivity, low electronic conductivity, and low activation energy. The solid electrolytes studied by scientists include inorganic solid electrolytes, solid polymer electrolytes, and solid-liquid composite electrolytes. In the inorganic solid electrolyte, Li+ is in a state of flow dynamics and migrates through the pores and/or interstitial positions in the electrolyte. 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: Problems and solutions of lithium batteries in my country