Preparation method of lithium ion battery anode composite material and special device thereof

Abstract

The invention discloses a preparation method of a lithium ion battery anode composite material and a special device thereof. The preparation method is characterized by comprising a first scheme, a second scheme and a third scheme, in the first scheme, a plasma-enhanced chemical vapor deposition method is used for synthesizing sp2-hybridized and carbon nano-material-coated lithium ion battery anode material LiFePO4 growing in-situ; in the second scheme, a direct plasma polymerization method is used for preparing LiFePO4 / conductive macromolecular composite material; and in the third scheme, a plasma in-situ polymerization method is used for preparing LiFePO4 / conductive macromolecular composite material. The special device for preparing the anode composite material comprises a plasma high-temperature quartz tube-type furnace, one end of the plasma high-temperature quartz tube-type furnace is provided with a reducing gas inlet pipe and a reaction gas inlet pipe and the other end of the same is provided with a gas suction pipe, and an inductance coupling plasma coil with two ends connected with radio frequency power sources is wound on the outer surface of the furnace. Tthe preparation method has the advantages of effectively improving the electric conductivity of the lithium ion battery and being simple in technological process, and the special device is simple in structure and convenient in operation.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to a method for preparing a positive electrode composite material of the lithium ion battery and a special device thereof. Background technique [0002] Lithium-ion battery is a new generation of green high-energy battery. It has many advantages such as high voltage, high energy density, good cycle performance, small self-discharge, no memory effect, and wide operating temperature range. It is widely used in mobile phones, notebook computers, UPS, Camcorders, various portable electric tools, electronic instruments, weaponry, etc. also have good application prospects in electric vehicles. The key to the rapid development of lithium-ion batteries lies in the development of lithium-ion battery cathode materials. [0003] At present, LiFePO is mainly used as the cathode material of lithium-ion batteries. 4 , due to its theoretical specific capacity (170 mAh / g) and high voltage plateau (3.4 V vs...

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Problems solved by technology

[0005] (1) LiFePO 4 The surface-coated carbon layer is mainly sp2 hybridized carbon nanomaterials doped into LiFePO as a conductive agent. 4 powder, can increase LiFePO 4 Surface electronic conductivity, and improve the charge and discharge performance of the material at a large current density, but the incorporation of carbon nanomaterials generally adopts the method of mechanical mixing, and generally requires more than 2 heating processes, and its preparation process is complicated; LiFePO due to mechanical mixing 4 / carbon nanomaterial composites, LiFePO 4 The uniformity of mixing with carbon nanomaterials is poor, and there are gaps between the materials that cannot be tightly combined, so that the actual packing density cannot be effectively improved, so it is easy to reduce the energy density of the electrode, so that the performance of the battery cannot be effectively improved; at the same time, carbon is inactive. Material and low density, the addition of carbon materials will reduce the LiFePO in the battery 4 filling volume

In addition, carbon materials cannot adsorb the lithium battery electrolyte well, which reduces the efficiency of the positive electrode material LiFePO. 4 utilization, thus affecting the performance of the battery

[0006] (2) LiFePO 4 The method of surface coating conductive polymer material can not only increase the LiFePO 4 conductivity, and can improve the LiFePO 4 The dispersion performance of the conductive polymer and the control of its particle size. At present, the surface coating of conductive polymers mainly adopts wet coating. The LiFePO to be prepared 4 Then disperse in the solvent, add the conductive polymer polymer monomer, the polymerization reaction occurs under the action of the initiator, and the conductive polymer is coated on LiFePO 4 Surface, then solid-liquid separation, drying to obtain conductive polymer coated LiFePO 4 However, this wet coating technology not only has a complicated process, but also cannot make the conductive polymer material evenly distributed in LiFePO 4 The surface is not conducive to LiFePO 4 The close combination with the conductive polymer material makes its actual packing density unable to be effectively increased, so it is easy to reduce the energy density of the electrode, so that the performance of the battery cannot be effectively improved

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