Silicon carbon negative electrode material, preparation method of silicon carbon negative electrode material and lithium ion battery

Abstract

The invention relates to a silicon carbon negative electrode material, a preparation method of the silicon carbon negative electrode material and a lithium ion battery. The preparation method comprises the steps of firstly mixing an organosilicon compound with a reducing agent, and reacting the organosilicon compound and the reducing agent to obtain a silicon pyrolysis material; then mixing the silicon pyrolysis material with graphite nodules to obtain a silicon pyrolysis carbon material; and etching the obtained silicon pyrolysis carbon material in a acid solution, mixing the etched silicon pyrolysis carbon material with a saline solution containing metal ions, and depositing metal and metal oxides to obtain the silicon carbon negative electrode material. According to the preparation method, the organosilicon, which is cheap and is easily available, is taken as a raw material, and the surface of the prepared composite silicon carbon material is covered with a metal layer with favorable electric conductivity and a metal oxide layer to form a conductive network, so that the electric conductivity of the silicon carbon negative electrode material is improved. Meanwhile, the metal and the metal oxides used for packing can efficiently lower the volume expansion and the mechanical stress in the charge and discharge processes of lithium ions, thereby prolonging the cycle life of the prepared composite material.

Description

technical field [0001] The invention relates to the technical field of electrode materials, in particular to a silicon-carbon negative electrode material, a preparation method thereof and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in civilian and military fields due to their advantages such as high working voltage, large specific energy, small self-discharge and less environmental pollution. Among them, the negative electrode material has an important impact on the safety, cycle life and energy density of lithium batteries, and is a key factor in the technological progress of lithium-ion batteries. [0003] At present, the negative electrode material widely used in lithium-ion batteries is graphite material, which has the advantages of cheap and easy to obtain, light weight and small thermal expansion coefficient, but its theoretical lithium storage capacity is only 372mAh / g. With the rapid development of science and technology...

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Problems solved by technology

[0004] The prior art discloses the technology of depositing nano-silicon particles in graphite by chemical deposition to prepare silicon-carbon composite materials, and then intercalating lithium between graphite layers to form lithium-ion battery negative electrode materials. However, in this technology, lithium ions are intercalated During the process, the body is prone to severe expansion, which will cause the material to pulverize after repeated charging and discharging, and the electrode material will partially fall off, which greatly reduces the battery life; at the same time, the conductivity of silicon is not as good as that of carbon materials, making the electrode material prepared The conductive properties of the

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