A kind of preparation method of porous silicon/carbon composite material

Abstract

The invention discloses a preparation method of a porous silicon / carbon composite material. The preparation method comprises the following steps: mixing decomposable silicide and a carbon source by a ball mill, carrying out heat treatment for 4-6 hours at 300-400 DEG C first, and then carrying out heat treatment for 12-20 hours at 600-800 DEG C, wherein the heat treatment process is carried out in a mixture of a protective gas and air and the volume ratio f the protective gas to the air is (10-50): 1; and treating a product obtained after heat treatment for 1-8 hours in an acid mixture of hydrochloric acid and hydrofluoric acid, and then centrifuging and drying to obtain the porous silicon / carbon composite material. The preparation method disclosed by the invention has the advantages that the preparation process is simple and convenient, a template or reduction treatment by metals is not required, and the used raw materials are industrial finished-products, thus being convenient for industrial production; the porous silicon / carbon composite material prepared by using the preparation method is adjustable in pore and size, and has relatively high coulombic efficiency and cycle stability when being used as a cathode material of a lithium ion battery.

Description

technical field [0001] The invention belongs to the field of composite material preparation, and in particular relates to a preparation method of a porous silicon / carbon composite material. Background technique [0002] Silicon material is the current research hotspot of lithium-ion battery anode materials, with the highest specific capacity (4200mAh / g). However, the lithium-silicon alloy formed during the lithium intercalation and deintercalation process has a huge volume expansion change, which leads to powdering, crushing and final shedding of the electrode material, and a sharp decline in the cycle performance of the material. [0003] At present, in order to alleviate the capacity fading caused by the volume effect of silicon materials during charging and discharging, research on silicon anodes at home and abroad mainly focuses on the following aspects: [0004] (1) Reduce the particle size of silicon powder, such as using nano-silicon powder, the specific capacity can...

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Problems solved by technology

[0005] (2) Preparation of nanostructured silicon materials with special morphology, such as silicon nanotubes, silicon nanowires, porous silicon, etc., but this method requires high cost and low output, and is only suitable for laboratory research [C.K.Chan , H.L.Peng, G.Liu, K.McIlwrath, Χ.F.Zhang, R.A.Huggins, Y.Cui, Nat.Nanotechno1.3 (2008) 31; Μ.H.Park, Μ.G.Kim, J.Joo , K. Kim, J. Kim, S. Ahn, Y. Cui, J. Cho, Nano Lett. 9 (2009) 3844.]

[0006] (3) Composite silicon with a material with good electronic conductivity, and the charge transfer resistance between active materials is significantly reduced, but this material with good electronic conductivity is expensive and not suitable for large-scale production [Y.YujLGujC.B. Zhuj S. Tsukimotoj P.A. van Akenj J. Maierj Adv. Mater. 22 (2010) 2247]

[0010] The synthesis process in the above-mentioned disclosed preparation method is complicated, and templates or the reduction of metals are required, which will inevitably lead to the complexity of the process and the increase of cost, which is not conducive to industrial production and application.

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