Performance analysis and industry development of cathode materials for lithium iron phosphate batteries

by:CTECHi     2021-07-26

Development of lithium iron phosphate battery cathode material industry, performance of lithium battery cathode material. Cathode materials account for more than 40% of the total cost of lithium batteries. Cathode materials are one of the key materials that determine the performance of lithium batteries. It is also the main source of lithium ions in current commercial lithium-ion batteries. The impact of ion batteries is greater. The main constituent materials for the development of lithium iron phosphate battery cathode material industry for lithium batteries include electrolytes, separator materials, and anode and cathode materials. Cathode materials occupies a large proportion, because the performance of cathode materials directly affects the performance of lithium-ion batteries, and its cost directly determines the cost of the battery. Currently marketed cathode materials for lithium batteries include lithium cobalt oxide, lithium manganate, lithium iron phosphate, and ternary materials. Due to the abundant metal resources such as lithium, cobalt, manganese and nickel required for the production of lithium battery cathode materials, the downstream application market for lithium batteries such as consumer electronics and new energy vehicles has expanded rapidly. In recent years, China's lithium battery cathode material industry has continued to grow and develop . The domestic lithium battery cathode material industry is highly concentrated, and three major lithium battery cathode material industry bases have been formed in the Beijing-Tianjin area, the middle and lower reaches of the Yangtze River and South China. With the rapid development of the new energy vehicle industry, we assume that the global production and sales of new energy vehicles will be 3 million in 2020, and the average battery capacity of a single vehicle is 40KWH. Then by 2020, the global demand for automotive power batteries is expected to be 120GWH. Then the global demand for lithium-ion batteries by 2020 is about 240GWH. According to the calculation of 2.4kg cathode material per KWH lithium battery, the global cathode material demand will reach 576,000 tons in 2020, corresponding to the output in 2016, and the compound annual growth rate will reach 17.71%. Therefore, at present, the industry demand growth rate of the entire cathode material industry in the next few years is slower than the industry expansion rate. Lithium iron phosphate and lithium manganate materials do not have much room for technological breakthroughs in basic research, and their energy density and main technical indicators are close to their application limits. From the perspective of technological progress, ternary lithium battery materials have gradually become the mainstream of power lithium battery cathode materials due to their advantages of high energy density, longer cycle life, and higher reliability. The basic requirements of lithium battery cathode materials are: First, the material itself has a high potential, so that a large potential difference can be formed between the material and the anode material, resulting in a battery design with high energy density; at the same time, the insertion and extraction of charged ions has little effect on the electrode potential. In the charging and discharging process, there will be no excessive voltage fluctuations and no adverse effects on other electrical systems in the system. Second, the material has a high lithium content and the intercalation and deintercalation of lithium ions is reversible. This is a prerequisite for high capacity. Some cathode materials have a high theoretical capacity, but half of the lithium ions lose their activity after the first intercalation. Such materials cannot be put into commercial use. Third, the diffusion coefficient of lithium ions is large, the movement of lithium ions inside the material is faster, and the ability to intercalate and deintercalate is strong. It is a factor that affects the internal resistance of the cell and also a factor that affects the power characteristics. Fourth, the material has a large specific surface area and a large number of lithium insertion sites. The surface area is large, and the insertion channel of the lithium battery is relatively short, so it is easier to insert and deintercalate. While the channel is shallow, the location for lithium insertion should be sufficient. Fifth, it has good compatibility and thermal stability with lithium battery electrolyte, which is due to safety considerations. The positive electrode material does not easily react with the electrolyte, and is still structurally stable at higher temperatures and still does not easily react with the electrolyte. Such a material will not provide heat for the extra heat accumulation of the battery cell, and can reduce the probability of the battery cell entering the self-heating stage. Sixth, the materials are easily available and the processing performance is good. Low cost, easy processing of materials into electrodes, and stable electrode structure are favorable conditions for the popularization and application of materials. What effect does the cathode material have on the performance of lithium batteries? Battery Energy Density Each positive electrode material has its theoretical energy density. When a positive electrode material is selected, the upper limit of the battery energy density is selected. The amount design of the positive electrode material and the tap density during the manufacturing process also have an impact on the energy density of the finished battery cell. The types of cathode materials with different cell power densities determine the general range of lithium battery charge and discharge power. Some details of the material, as an auxiliary factor, will also affect the power characteristics. For example, the stability of the crystal structure of the cathode material, particle size, doping atoms, carbon coating process, material preparation method, etc. The above factors ultimately affect the power density of lithium batteries by affecting the ability of the cathode material to accommodate lithium ions and the patency of the deintercalation and insertion channels. There are many factors that affect the cycle life of the battery cell. The positive electrode material is related to the loss of the active material of the positive electrode material in the cycle, and the capacity of the positive electrode to accommodate lithium ions caused by the collapse of the material structure during the charging and discharging process. The attenuation. The impurity components in the positive electrode material, such as elemental iron and trivalent iron, will interact with the electrolyte and cause adverse side reactions or cause internal micro short circuits. Lithium battery materials generally have a current situation of overcapacity in the low-end and low-end products and in short supply of high-end products. Among them, cathode materials, anode materials, and electrolytes have gradually become self-sufficient. As the technical barriers of anode materials and electrolytes are relatively low, the cost advantage of Chinese companies is obviously strong globally. The rapid development of ternary materials has gradually become the mainstream.

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