A kind of preparation method of hard carbon negative electrode material

Abstract

The invention provides a preparation method of a hard carbon negative electrode material. The preparation method comprises steps as follows: aggregates and asphalt with a softening point being 200-280DEG C are mixed and kneaded at 300-380 DEG C, and a mixed material is obtained; the mixed material is subjected to molding and then is carbonized at 400-500 DEG C, and a precursor is obtained; the precursor is crushed and carbonized at 900-1400 DEG C, and the hard carbon negative electrode material is obtained. Compared with the prior art, the preparation method has the beneficial effects as follows: air and asphalt can be sufficiently and uniformly mixed in a mixing and kneading pot, a uniform cross-linking reaction is performed, oxygen-containing functional groups on the surface of asphaltare increased through oxidizing modification, and superior conditions are created for production of a large quantity of uniform lithium storage holes based on carbonization.

Description

technical field [0001] The invention relates to a hard carbon negative electrode material that solves the problem of high-power charging and discharging, and is an ideal power source for high-end energy storage systems such as pure electric vehicles, hybrid vehicles, and space technology in the future. Background technique [0002] 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 industry for countries to get rid of economic recession and seize the commanding heights of future development. In the field of new energy, lithium-ion batteries have been widely used in portable electronic appliances such as cameras, mobile phones, and notebook computers due to their excellent characteristics such as high energy density, high power density, good cycle performance, environmental friendliness, structural diversity, and low price. widely used. In the p...

AI Technical Summary

Problems solved by technology

[0004] 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 + The reaction forms a lithium salt, the so-called SEI (Solid electrode surface) film, which reduces the first charge and discharge capacity and Coulombic efficiency;

[0005] 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 peel off , or even pulverized, resulting in a decrease in lithium intercalation capacity and a shortened cycle life;

[0006] 3. The electrochemical behavior of natural graphite as a negative electrode material at low temperature (such as -20°C) is not ideal, mainly due to the slow diffusion of lithium ions in graphite, not the electrolyte and "solid electrolyte interface" (solid electrolyte interface) , referred to as the reason for the low conductivity of the SEI film;

[0007] 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 lower than that of high-quality natural graphite or artificial graphite. 300mAh / g, the charge and discharge efficiency of the first cycle is lower than 80%, and the cycle performance is not ideal

[0008] 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.

[0011] 1. The irreversible capacity of the first charge and discharge is relatively high;

[0012] 2. The output voltage is low;

[0013] 3. No obvious charging and discharging platform potential

[0014] 4. The market price is higher

[0019] The existing hard carbon negative electrode material is prepared with high softening point pitch as a precursor, and the method of direct oxidation of high softening point pitch is adopted. This method oxidizes unevenly and can only oxidize the high softening point pitch on the surface layer, so the oxidation is uneven, resulting in low capacity

Images