Lithium ion battery cathode material classification have?

Source: 2020 - 04 - 12 21:08 hits: lithium ion battery cathode material classification have? 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. , therefore, the research and development has better electrochemical performance of new anode materials and the modification of existing materials 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. Embedded anode materials: the most typical embedded 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 and carbon microspheres. Hard carbon is hard to graphitization in above 2500 ℃. Graphite discharge capacity is 3500 mah/g, a layered structure. The same layer of carbon atoms arranged in hexagonal, two layer by the van der Waals force. 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. Need to point out that graphite is higher than that in hard carbon materials discharge capacity, except with the graphite with the same embedding mechanism, hard carbon there is a small hole or defects in structure, can be used in the storage of Li + and nested. But because of the low cycle efficiency, voltage change with capacity is big, and lack of stable discharge platform, the application of hard carbon as anode material is limited. Alloy anode materials: alloying lithium 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 with various metal at room temperature ( 锡、硅、锌、铝、某人、通用电气、铅、镁、钙、,Bi, Pt, Ag)、非盟、Cd, Hg等) Reaction, the charging and discharging mechanism for alloying and reverse alloying. 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. Transformational cathode materials: the transition of the current report 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. Figure 2 conversion of some kind of anode material first discharge capacity is 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.