Lithium ion battery cathode material classification is introduced

Source: 2020 - 04 - This was hits: 14 of the lithium ion battery cathode material classification ideal lithium ion battery cathode material should be able to accommodate a large number of lithium ion, high ionic conductivity and electrical conductivity, and good stability. The existing anode material is hard to meet the above requirements at the same time. Development, therefore, has better electrochemical performance of new anode materials and the existing materials modified has been a hot research topic in the field of lithium ion battery anode materials. At present, the anode material can be divided into three types: embedded anode material, alloy anode material and anode material. 一个。 The most typical embedded embedded cathode material is carbon anode materials. Depending on the degree of graphitization of carbon materials can be divided into soft and hard carbon carbon and graphite. Commonly used soft carbon material with petroleum coke, needle coke, carbon fiber, carbon microspheres, etc. Hard carbon is hard to graphitization in above 2500 ℃. Graphite discharge capacity is 350 mah/g, has a layered structure, the same layer of carbon atoms are arranged in hexagonal, the van der Waals force between layer and layer. Li - formed between lithium ion can be embedded into the graphite layer gic。 Good electrical conductivity of graphite materials, high crystallinity, charge and discharge platform stability, is the most commercial lithium ion battery cathode materials. In addition to the graphite, other lithium storage mechanism of carbon material is the same. It should be pointed out that, graphite is higher than that in hard carbon materials discharge ability, because in addition to the graphite with the same embedding mechanism, hard carbon there is a small hole or defects in structure, can be used for the storage of Li + and remove [ 15] 。 But due to the low cycle efficiency and unstable voltage change with capacity big, discharge platform, the application of hard carbon as anode material is limited. B。 Alloy anode materials for lithium alloying storage material is refers to the metal and its alloy, can with lithium alloying reaction intermediate compounds and complexes. It is reported that lithium can be at room temperature and tin, copper, zinc, aluminum, antimony, silicon, lead, magnesium, calcium, arsenic, bismuth, platinum, silver, gold, cadmium, mercury and other metals, the charging and discharging mechanism for alloying and reverse alloying reaction. Generally speaking, the theory of alloy anode materials for capacity and charge density is much higher than embedded type anode material. Embedded at the same time, this kind of material of high potential for lithium, lithium deposits, it is hard to under the condition of large current charge and discharge, lithium and dendrites will not produce, this could lead to short circuit batteries, it is of great significance for high power devices. C。 Convert the transition of the anode materials is reported as many as 10 kinds of metal materials, mainly refers to the Co, Ni, Mn, Fe, V, Ti, Mo, W, Cr, Cu, Ru and other elements of transition metal oxides, sulfide, nitrogen, phosphate and fluoride. In the past, people don't think this kind of material is promising. No lithium ion embedded in the spatial structure of the material and the escape of space, is not in conformity with the traditional mechanism of lithium ion Mosaic, room temperature and the reaction of lithium is considered to be irreversible. Until some transition metal oxides were found to have high reversible discharge capacity, Is 3 times of graphite) The material is gradually attracted the attention of the researchers. Figure 2 shows the transformation of certain classes of the anode materials for the first discharge volume. Different from the above three kinds of cathode materials, lithium titanate (Li4Ti5O12 spinel structure has been more and more attention. The working voltage of Li4Ti5O12 is 1. 5 v, compared with common anode materials, working voltage is relatively high. Does not decompose under the voltage, electrolyte. Therefore, lithium titanate is used as anode materials of the battery. In addition, the lithium titanate material in embedded and volume change before and after the removal of lithium ion is not big, is a kind of safety performance prominent 'zero strain material, become the hotspot of the next generation of lithium ion battery energy storage power station.