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Analysis Of Hot Energy Of Lithium Battery High Energy Technology
Jun 03, 2017

High energy density development routes include: high voltage cathode material, high grams of positive and negative material capacity. High voltage cathode material usually refers to the battery using a voltage higher than 4.2V cathode material. Lithium cobalt oxide, lithium manganese oxide, ternary have high voltage materials.


One of the high-voltage lithium cobalt oxide commercialization has been very mature, a large number of high-end digital products, the energy density higher than the ordinary three-element battery At present, high voltage lithium cobalt oxide battery voltage is usually 4.35V, the next 3-5 years 4.4V, 4.5V high voltage lithium cobalt oxide battery or large-scale application.


Ternary high voltage cathode material application is very little, basically in the research stage. But the ternary high-voltage cathode material may be the future to achieve 300Wh / kg energy density breakthrough.


At present, the capacity of the ternary NCM811 material has exceeded 180mAh / g, and the high voltage can be achieved by coating or mixing. At the same time, the capacity of the ternary NCM811 is increased (the high voltage material is equivalent to the activation of lithium with no activity at low voltage, Limit the use of materials). But the current high-voltage ternary material there are many technical problems are not resolved, the stability of the material itself has not yet been resolved.


Lithium manganate cathode material charge potential up to 4.7V, lattice structure is very stable.


At present, lithium manganese oxide battery energy density 150Wh / kg, higher than the lithium iron phosphate battery energy density. Lithium manganate crystal structure is stable, good thermal stability, lithium manganese battery safety is very high. Which lithium manganese oxide - lithium titanate battery in the fast charge area has an excellent application prospects.


Lithium iron phosphate due to capacity has been close to the theory, through the high voltage is difficult to activate more lithium, the effect is very limited. However, lithium iron phosphate (vanadium) lithium, lithium iron phosphate energy density is higher, is a lot of research institutions and business research hot areas, lithium iron phosphate molecules containing two lithium ions, the theoretical grams of capacity up to 332mAh / g.


High voltage cathode materials require high voltage electrolytic solution to make the entire battery system work well. To stabilize the electrolyte in a high-voltage environment, it is necessary to improve the oxidation resistance of the solvent while blocking the direct contact between the positive electrode and the electrolyte. Methods for improving the oxidation resistance of electrolytes include fluorinated solvents, the price of fluorinated solvents is too high, and large-scale applications are difficult to achieve.


Other new antioxidant solvents such as ionic liquids, with good ionic conductivity and antioxidant capacity, is an excellent lithium battery solvent, but the current high prices, it is difficult to large-scale promotion. The method of blocking the direct contact between the electrolyte and the electrolyte comprises a positive electrode material coating and a positive electrode film forming additive. Cathode material coating and additives research is very much, the effect is very obvious, is an important means to enhance the future of antioxidant.


Ternary materials, large-scale development and application of relatively late, in terms of energy density there is a lot of room for improvement. At present, mainstream material manufacturers have been able to do 180mAh / g level, and ternary high nickel theoretical capacity of up to 270mAh / g, there is a lot of room for improvement. At present, high-capacity ternary materials are sensitive to water, the first low efficiency and poor circulation. With the technological progress of these problems or can be resolved, lithium-rich cathode is also a lot of research institutions and business research hot spots.


On the other hand silicon anode material can greatly enhance the negative capacity of the negative. Has been the anode material has been graphite-based, graphite anode technology has been very mature, the actual capacity has been very close to the theoretical capacity. To increase the negative grams of capacity, must use other materials.


And silicon and other metal anode is a very suitable choice, the earliest Japanese sony with tin composite anode to enhance the battery energy density, has been introduced to the market high-capacity 18650 products. In recent years, silicon composite anode has been taken seriously, including silicon and carbon composite anode and silicon oxide - graphite composite anode technology is more mature, Japan and South Korea enterprises have been applied to high-capacity products.


At present, the domestic material factory, cell plant also gradually introduced silicon-based negative high-capacity products. The theoretical weight of silicon is 4200 mAh / g, but the volume expansion effect is very large, so the use of graphite composite to reduce the impact of expansion. The metal lithium anode has a higher capacity than the silicon anode, but its dendritic problem is not solved and the safety risk is high. And metal lithium and electrolyte easily react, reduce its cycle life. At present, lithium metal battery is also difficult to large-scale market to the market.