Preparation method and application of a coal tar pitch-based lithium-ion battery negative electrode material

Abstract

The invention discloses a preparation method of a coal pitch-based lithium ion battery negative electrode material. Pitch balls with a diameter of less than 100 μm and a softening point of 90° C. to 130° C. are added with a sulfonating agent to be sulfonated at room temperature, and then sulfonated at a temperature of 400 to 500° C. The sulfonating agent is decomposed at ℃, the asphalt balls from which the sulfonating agent has been removed are placed in the reaction vessel, and air-oxidized at 280-350 ℃. Hard carbon anode materials with different median diameters were obtained. The invention has the advantages of high yield, simple process, convenient operation and very low cost compared with mesophase carbon microspheres.

Description

technical field [0001] The invention relates to the field of coal chemical industry and the field of carbon materials, and in particular relates to a method for preparing negative electrode materials of lithium-ion batteries by using coal tar pitch. Background technique [0002] Spherical asphalt is widely used in blast furnace iron channel material, blast furnace gunning material, ramming material and castable material, amorphous refractory material, and additive of carbon material. ability. Refractory materials require spherical asphalt with a diameter of more than 100 μm. Therefore, during the production process, if the diameter is less than 100 μm, it will become waste, and it will become a raw material after re-melting, which greatly increases the operating cost of the factory. [0003] With the depletion of fossil fuels, the energy crisis has become the focus of global attention. Therefore, the development of new energy is currently listed as an important strategic in...

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Problems solved by technology

[0006] (1) Due to the presence of carbonyl, carboxyl and other surface functional groups on the edge of natural or artificial graphite layers, under a certain potential, such surface functional groups are very easy to oxidize with the electrolyte, and further react with Li+ to form lithium salts, the so-called SEI (Solid electrode surface) film, which reduces the first charge and discharge capacity and Coulombic efficiency;

[0007] (2) In addition, during the repeated lithium intercalation-delithiation process of natural or artificial graphite, the surface chemical functional groups and solvents, such as PC, DME, DMSO, etc., are co-embedded by solvents to form Li-GIC interlayer compounds, which cause the graphite layer to expand and generate Peeling or even pulverization, which will lead to a decrease in lithium intercalation capacity and a shortened cycle life;

[0008] (3) The electrochemical behavior of natural graphite as an anode material at low temperatures (such as -20°C) is not ideal, mainly due to the slow diffusion of lithium ions in graphite, rather than the electrolyte and "solid electrolyte interface film" (solid electrolyte interface film). ), referred to as the reason for the low conductivity of the SEI film;

[0009] (4) For ordinary natural graphite, due to the incomplete graphitization process in the natural evolution process, there are natural impurities and defect structures, so the insertion behavior of lithium cannot be compared with high-quality natural graphite or artificial graphite, and the general capacity is low At 300mAh / g, the charge and discharge efficiency of the first cycle is lower than 80%, and the cycle performance is not ideal

[0010] (5) It cannot be charged and discharged with high power. Therefore, it cannot be an ideal power supply for high-end energy storage systems such as pure electric vehicles, hybrid vehicles, and space technology in the future.

[0012] Among them, mesophase carbon microspheres, because of their spherical shape and good fluidity, are easy to make excellent high-density electrodes, and have a high degree of graphitization. The structure makes it easy to form a dense SEI film on the surface and effectively inhibits the exfoliation or pulverization of the graphite layer, but the disadvantage is

[0013] ① The irreversible capacity of the first charge and discharge is relatively high;

[0014] ②The output voltage is low;

[0015] ③No obvious charging and discharging platform potential

[0016] ④The market price is higher

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