Time:2024.12.04Browse:0
How do 3.7 volt 18650 lithium battery work?
During the entire battery charging process, the lithium-containing compound in the positive electrode changes. Lithium loses an electron and becomes lithium ion (Li+). The lithium ion is detached from the positive electrode material. The electrolyte filled between the two electrodes acts as a crossing medium, allowing the lithium ion to escape from the positive electrode. The positive electrode moves toward the negative electrode and is eventually embedded in the negative electrode material at the other end of the battery. At this point, the battery cathode material is a lithium-rich case. In addition, the electronic devices in the external circuit of the rechargeable battery also transfer from positive to negative. When the external circuit electronic devices run to negative, the Li+ in the raw material is reduced to Li. All rechargeable battery systems are in a charge balance state. The entire charging process is opposite to the discharging process. During the entire process, 3.7 volt 18650 lithium battery are less likely to destroy their lattice constants and chemical structures throughout the insertion and sliding process.
What are the common 3.7 volt 18650 lithium battery on the market?
The unique energy storage material of lithium batteries is the cathode material. The energy ratio of the battery system depends on its specific energy and compatibility. Since its commercial application, most battery cathode materials are carbon materials, and more are high-purity graphite. In contrast, the choice of battery cathode materials is wide. With the development of new energy vehicles all over the world, in order to find more powerful battery working capacity, greater energy ratio, and longer service life, it has also become the overall goal of various power lithium-ion battery manufacturers, resulting in the sales of electrode materials in Scientific research and development trends in the market are always hot.
At present, several cathode materials used in new energy vehicles are as follows:
1. Lithium cobalt oxide (LiCoO2)
Lithium cobalt oxide is the first commercial cathode material for 3.7 volt 18650 lithium battery because it can be manufactured by manufacturers in a short time and is suitable for promotion in the industrial chain. Therefore, it is the first commercial cathode material for batteries. However, due to the small specific capacity of cobalt and the low cost of cobalt resources, cobalt has toxic side effects, which limits the development trend of lithium cobalt metal oxides.
2.Lithium manganese oxide
Lithium manganese oxide is mainly composed of LiMnO2 and LiMn2O4. During the entire charging process, since the oxides of limno2 and limn2o4 mainly transform from a layered structure to a spinel structure, the volume attenuation coefficient is not high. In addition, raw materials will continue to produce lattice constants, which will result in fast cell volume decay coefficients. Therefore, application costs are high.
3.Lithium nickel manganate
Since manganese does not produce a valence state transition in the battery charge and discharge cycle system, it has the effect of stabilizing the structure. High voltage can produce higher kinetic energy, but it also increases the adverse reactions between the metal electrode and the electrolyte solution, resulting in a higher thermal resistance. Difference.
4.Lithium iron phosphate
Lithium phosphate battery raw materials have excellent production technology, low cost, and stable structure. The structure does not change greatly during the entire battery charging cycle.
However, its development trend also has some shortcomings: (1) The conductivity of electronic devices is low and the thermal diffusion coefficient of 3.7 volt 18650 lithium battery is low, which limits its ability to charge high-current batteries; (2) During the high-temperature calcination process, the compound is easily converted into Iron hydroxide, causing short circuit failure of rechargeable batteries; (3) Lithium phosphate batteries have low apparent density, and the vibration density of commercial products is only 1.0gcm-3, with a low volume ratio.
5. Ternary materials (li-ni-co-mn-o)
In recent years, due to different proportions of nickel, cobalt, and manganese, the cathode materials of ternary batteries can be broadened, so different types of raw materials have different advantages and disadvantages.
Three element responsibilities of ternary materials:
1. Ni: As the nickel content increases, the charge-discharge ratio increases. However, since Li, Ni and Ni2 are similar to Ni2, too much Ni2 and Li phase shift, resulting in the mixing of Li and Ni. The more Ni cations in the lithium layer, the more difficult it is to remove and insert the Li-ion battery, and the photocatalysis The worse the performance.
2. Co: Co can reduce the mixing and space-occupying damage of positive ions in the raw materials, make the flaky structure of the raw materials more and more stable, reduce the characteristic impedance value, increase the conductivity, and improve the characteristics and time characteristics of the circulation system;
3. mn: There are four types of mn in the raw materials, which can improve the stability and safety of the raw materials. However, if the manganese content is too high, the raw material can easily transform into a spinel structure, thereby destroying the original plate structure, resulting in a reduction in the volume of the raw material, and the characteristics of the circulation system.
The nickel-cobalt-manganese ternary material combines the advantages of lithium cobalt oxide, lithium nickel oxide and lithium manganate to form a three-phase eutectic system of LiCoO2/LiNiO2/LiMnO2, and its comprehensive performance is better than any single combination. compound, there is an obvious ternary synergistic effect. . Ternary materials have the advantages of large specific capacity, low cost, environmental protection, high heat resistance, and good safety factor. In recent years, with the technological improvement of ternary materials and the rapid development of new energy vehicles, it has occupied an important market share in the power lithium battery industry, and has also begun to gradually replace lithium cobalt oxide in the consumer lithium ion sales market.
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