I will teach you how to choose a lithium ion battery electrode material

Lithium-ion batteries are capable of secondary charging during use and belong to a secondary rechargeable battery. The main working principle is the repeated movement of lithium ions between positive and negative poles, regardless of the shape of the battery. Its main components are electrolytes, positive plates, negative plates, and diaphragm. At present, the international production of lithium-ion batteries is mainly concentrated in China, Japan, and South Korea. The main lithium-ion application markets are mobile phones and computers. With the continuous development of lithium-ion batteries, the application field is gradually expanding, and its use of positive polar materials has changed from monolithic to diversified. These include: olivine-type ferrous phosphate lithium, layered cobalt acid lithium, spinel type manganese acid, etc., to achieve the coexistence of a variety of materials. It can be seen from the development of technology that more new types of positive materials will be produced in future development. For the power cell's positive electrode material, it has strict requirements in terms of cost, safety performance, circulation capacity, and energy density. In the field of Applied materials, due to the high cost and low safety of lithium cobalt acid, it is usually applicable to ordinary consumer batteries in specific applications and it is difficult to meet the requirements of power batteries. The other materials listed above have been fully utilized in the current power cells. In lithium-ion battery material, the negative electrode material is an important component, which can have a great influence on the performance of the whole battery. At present, negative polar materials are mainly divided into two categories, one for commercial applications of carbon materials, such as natural graphite, soft carbon, and the other for non-carbon negative materials that are under research and development but have a good market outlook. For example, silicon-based materials, alloy materials, Sikkim materials, and so on.

1 Carbon negative material: This type of material, whether it is energy density, recycling capacity, or cost input, is a balanced negative material, and it is also the main material that promotes the birth of lithium-ion batteries. Carbon materials can be divided into two categories., Graphite carbon materials and hard carbon. Among them, the former mainly include artificial graphite and natural graphite. The formation process of artificial graphite is: at temperatures above 2500 °C, soft carbon materials are graphed and obtained. MCMB is a commonly used type of artificial graphite. Its structure is spherical and it's surface texture is relatively smooth. The diameter is approximately 5-40 μm. Due to the surface smoothness of the electrode, the reaction rate between the electrode surface and the electrolyte is reduced, and the irreversible capacity is reduced. At the same time, the spherical structure can facilitate the embedding and deactivation of lithium ions in any direction, and it has a great promotion effect on the stability of the structure. Natural graphite also has many advantages. It has higher Crystallinity, more embedding locations, and lower price. It is an ideal lithium-ion battery material. However, it also has certain disadvantages. For example, when reacting with the electrolyte, the compatibility is poor, and there are many defects on the surface during crushing, which will have a greater negative impact on the performance of its charging or discharge. In addition, the formation process of hard carbon is: at 2500 °C, it is difficult to implement graphed carbon materials, which are mainly pyrolytic carbon of a polymer compound. It can be seen through high magnification microscopy that it is made up of many nanometer spheres. Made of, The whole show a cluster of flowers, as shown in Figure 1. The amorphous area with a large number of Nanopore on its surface far exceeds the standard capacity of graphite in terms of capacity, which in turn has a great negative impact on the circulation capacity.

2 Silicon negative electrode material: Because Silicon material is rich in storage and cheap, it is ideal to apply it as a new type of negative electrode material to lithium-ion batteries. However, since Silicon is a semiconductor, the conductivity is poor, and during the embedding process it will expand several times the volume of the past, and the maximum expansion can reach 370 %, which will lead to active Silicon powder and fall off, making it difficult to fully contact with electrons., In turn, the capacity is rapidly reduced. If Silicon is to be well used in lithium-ion battery materials, it can be effectively controlled in the process of charging or discharging, and its capacity and circulation ability can be greatly guaranteed. You can do this in the following ways. First, you can use the nanometer-sized Silicon. Second, Silicon is combined with inactive Matrix, active matrix, and adhesive. Third, the use of Silicon films, it has been considered the next generation of the most suitable commercial negative materials.

3 Lithium-ion battery cathode material: Lithium cobalt acid as a cathode material was used earliest and is still the mainstream cathode material in consumer electronics products. Compared with other positive materials, lithium cobalt acid can be seen that the voltage in the process of operation is relatively high, the voltage operation is relatively stable when charging or discharging, and it can meet the requirements of high current, has strong cyclic performance, and has high conductivity. Materials and batteries and other processes are relatively stable. However, it also has many disadvantages. For example, resources are scarce, prices are higher, cobalt contains toxicity, and it has certain risks when used, and it can have adverse effects on the environment. In particular, its security cannot be effectively guaranteed, which will become an important factor that restricts its extensive development. Among the studies carried out on it, Metal cation such as Al 3 +, Mg2 +, and Ni2 + are the most widely doped, and with the continuous advancement of scientific research, At present, Metal cation doping forms such as Al 3 + and Mg2 + have been put into use. In the preparation of lithium cobalt acid, two methods are mainly included, namely solid phase synthesis and liquid phase synthesis. What is commonly used in industry is the high-temperature solid phase synthesis method. It mainly uses lithium salts, such as Li2CO3 or LiOH, and cobalt salts, such as CoCO3, to fuse at a ratio of 1:1. It is formed by Calcination at a high temperature of 600 °C to 900 °C. At present, the application of lithium cobalt acid materials in the market is mainly in the secondary battery market, and it is also the best choice for small high-density lithium-ion battery materials.

The three-element positive electrode material has a relatively significant three-element synergistic effect. Compared with lithium cobalt acid, it can be seen that there is a greater advantage in terms of thermal stability, and the production cost is relatively low, and it can become the best substitute material for lithium cobalt acid. However, its density is low and its recycling performance needs to be improved. For this, the improved synthesis process and ion doping can be used to adjust. The ternary material is mainly used in cylindrical lithium-ion batteries such as steel shells and aluminum shells, but its application is greatly limited due to the expansion factors in soft-pack batteries. In future applications, its development direction mainly has two aspects: First, to the direction of high manganese, mainly in Bluetooth, mobile phones and other small portable devices development. Second, in the direction of high nickel, mainly in electric bicycles, electric vehicles and other areas where the demand for energy density is high.

Lithium ferric phosphate has good recycling performance and thermal stability in charging and discharging, has strong safety guarantees during use, and the material is green and environmentally friendly, will not cause serious damage to the environment, and at the same time, the price is also relatively low. China's battery industry is considered to be the best material for large-scale battery module production. The main application areas at present are electric vehicles, portable mobile charging power sources, etc.. In the future, it will develop in the direction of energy storage power sources and portable power sources.

Lithium manganese oxide has strong safety and anti-overload in the application. Due to the abundant manganese resources in China, the price is relatively low, the pollution to the environment is small, non-toxic and harmless, and the industrial preparation operation is relatively simple. However, during the charging or discharge process, due to the instability of the spinel structure, the Jahn-Teller effect is easily produced, and the dissolution of manganese at high temperatures makes it easy to reduce the battery capacity, so its application is also greatly limited. At present, the application scope of Lithium manganese oxide is mainly small batteries, such as mobile phones, digital products, etc.. In terms of power cells, lithium iron phosphate can be replaced with each other, thus creating strong competition. Its development direction will be high energy, high density, low-cost trend.

Lithium-ion battery products have shown vigorous development. With the development of science and technology, smartphones, computers, and other products have been widely used. This will make the demand for lithium-ion batteries greater and bring greater development opportunities for them. At the same time, vehicle-mounted lithium ions and energy storage power supplies have gradually been developed, providing new growth points for lithium-ion batteries. Therefore, in the future development, it is necessary to strengthen the research on this aspect, so that the role of lithium-ion batteries will play a greater role, which will also lead to the continuous replacement of its battery materials.

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