Nitrogen-phosphorus doped two-dimensional carbon/silicon compound and preparation method and application thereof

Abstract

The invention discloses a nitrogen-phosphorus doped two-dimensional carbon / silicon compound and a preparation method and application thereof. The preparation method comprises the following steps 1, dissolving a carbon source in deionized water, then adding a silicon source, uniformly mixing, adding NaCl, uniformly mixing, drying the mixture to obtain a solid, and grinding the solid into powder, 2,putting the powder into a tubular furnace, calcining in protective gas, etching a NaCl template by using deionized water, and drying to obtain a two-dimensional carbon / silicon compound, and 3, dissolving the two-dimensional carbon / silicon compound and a nitrogen source in deionized water, stirring, then adding a phosphorus source and stirring and calcining in protective gas to obtain the nitrogen-phosphorus doped two-dimensional carbon / silicon compound. The nitrogen-phosphorus-doped two-dimensional carbon / silicon compound is low in cost, can be produced on a large scale, not only has a relatively high specific surface area and relatively good electron transmission performance, but also can greatly buffer the volume change of silicon in a lithium de-intercalation and intercalation process,is applied to a lithium ion battery negative electrode material, and has a very good application prospect.

Description

technical field [0001] The invention relates to the field of two-dimensional carbon / silicon composites, in particular to a nitrogen-phosphorus-doped two-dimensional carbon / silicon composite and its preparation method and application. Background technique [0002] With the rise of new energy vehicles, rechargeable lithium-ion batteries have attracted widespread attention. [0003] Among battery anode materials, silicon is one of the most promising anode candidate materials for next-generation lithium-ion batteries, which has low voltage and high theoretical specific capacity (formation of Li at room temperature 15 Si 4 phase is 3580mA / h g), in addition, its reserves are abundant (the second most abundant element in the earth's crust), and it is not harmful to the environment. However, during the charging and discharging process, the silicon anode volume expands by about 300%, which destroys the electrical contact between particles, irreversible anode material pulverization ...

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Problems solved by technology

[0005] Researchers have explored various shapes and structures of silicon-carbon composite materials, such as: pomegranate-like silicon-carbon composite materials (N.Liu, Z.Lu, J.Z h ao, M.T.McDowell, h.W.Lee, W.Z h ao, Y .Cui,Nat.Nanotechnol.2014,9,187;), silicon-carbon composites with egg yolk shell structure (N.Liu,h.Wu,M.T.McDowell,Y.Yao,C.Wang,Y.Cui,Nano Lett.2012 , 12, 3315;) etc. Compared with these structures, two-dimensional materials have higher specific surface area and better electron transport performance, so they have better application prospects. At present, there is no use of NaCl as a template to prepare nitrogen and phosphorus doped materials. The method of heterogeneous two-dimensional carbon / silicon composite negative electrode material, and the NaCl template can be cleaned up with deionized water in an environmentally friendly way, so the development of this kind of nitrogen-phosphorus-doped two-dimensional carbon-silicon composite negative electrode is simple, low-cost, and can be prepared in large quantities. Material methods are important

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