Anode materials for lithium-ion batteries

Early lithium batteries used metallic potassium as the negative electrode. Since potassium is an alkali metal and has low density, it has a high electrochemical equivalent (3860mA·h/g) and the most negative electrode potential (-3.045V). However, dendrites are easily formed during the charging process, which can pierce the separator and cause an internal short circuit of the battery. Therefore, secondary batteries using metallic lithium as the negative electrode have poor safety and poor cycle performance, and have not been put into practical use. In order to overcome the above shortcomings of lithium anodes, graphite-based intercalation compounds have been developed as anode materials for carp-ion batteries, which solve the safety problem of lithium-ion secondary batteries while sacrificing capacity. Currently commercialized lithium-ion batteries mainly use carbon negative electrode materials.

Although graphite anode materials have been successfully commercialized, they still have some weaknesses that are difficult to overcome: The potential of the carbon electrode is very close to that of potassium metal. When the battery is overcharged, metal chloride is easily precipitated on the surface of the carbon electrode, which may form lichen branches. crystals can cause a short circuit, so the graphite negative electrode needs to have more remaining capacity than the positive electrode; @ At high temperatures, the SEI film on the carbon negative electrode may decompose and cause the battery to catch fire, so there are temperature restrictions on the use of carp ion batteries; @ The performance of the carbon negative electrode is affected by The preparation process has a great impact. In view of the above situation, finding non-carbon anode materials with better performance is still an important topic in potassium-ion battery research. Non-carbon-based negative electrode materials mainly include the following types: nitrides, silicon-based materials, tin-based materials, new alloys, bowl oxides, nano-oxides and other negative electrode materials.

At present, the research on negative electrode materials for lithium-ion batteries shows a diversified development trend. Modification treatment of traditional graphite materials (such as oxidation, copper plating, coating polymer pyrolytic carbon on the graphite surface, etc.), metals, alloys, Sn-based alloys and transition metal nitrides, etc., especially the modification treatment of graphite materials , can significantly improve its charge and discharge performance and further increase the specific capacity.

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