Lithium secondary battery cathode material and preparation method thereof

Abstract

The invention relates to a lithium secondary battery cathode material and a preparation method thereof, and belongs to the technology of the lithium secondary battery cathode material. The cathode material is prepared from montmorillonite or organic modified montmorillonite, acetylene black and polyvinylidene fluoride. The preparation process of the cathode material comprises the following steps of: mixing the montmorillonite or the organic modified montmorillonite, the acetylene black and the polyvinylidene fluoride in mass ratio; putting the mixture into a mortar for grinding; adding N-methyl pyrrolidone in the mass ratio of the mixture; continuously grinding the mixture, and coating the mixture onto an aluminum foil; and drying the mixture in a blower drying oven and a vacuum drying oven in sequence to obtain the lithium secondary battery cathode material. The prepared lithium secondary battery cathode material has the advantages of high reversible specific capacity, good dimensional stability in the process of charging and discharging, low price, availability, large scale production and wide application prospect.

Description

technical field [0001] The invention relates to a lithium secondary battery negative electrode material and a preparation method thereof, belonging to the lithium secondary battery negative electrode material technology. Background technique [0002] The commercialization of lithium secondary batteries, that is, since the birth of lithium secondary batteries, the main researched negative electrode materials include metallic lithium, graphitized carbon materials, amorphous carbon materials, nitrides, tin-based materials, new alloys, etc. The following will focus on the characteristics of the following types of anode materials for lithium secondary batteries: [0003] (1) Although metal lithium has a specific capacity as high as 3860mAh / g, when it is used in lithium secondary batteries, due to the reaction of metal lithium and electrolyte to form a passivation film, it will form deposited lithium on the concave and convex parts of the metal lithium surface during charging and ...

AI Technical Summary

Problems solved by technology

At the same time, this type of negative electrode material will cause a decrease in the regularity of the graphite layer during lithium insertion and delithiation, resulting in a decrease in cycle performance. At the same time, when the specific capacity of the positive electrode material of the lithium secondary battery is greater than 372mAh / g, the specific capacity of the negative electrode material is relatively low. Will greatly limit the performance of the battery in all aspects

[0005] (3) The research on amorphous carbon materials is mainly due to the need for high-temperature treatment of graphitized carbon. After research, it is found that although its reversible capacity is high, even up to 900mAh / g, the cycle performance is not ideal, and the reversible lithium storage capacity generally decreases with The cycle decays faster

[0006] (4) When binary or ternary alloys are used as negative electrode materials for lithium secondary batteries, although the reversible specific capacity is greatly improved, for metal alloys (such as CuSn, SnSb, LiMg, Co 3 sn 2 etc.) A problem that cannot be ignored is the dimensional stability of the alloy during charging and discharging, that is, with the progress of lithium intercalation / delithiation, the size and volume of the alloy will change greatly, which is important for the performance of lithium secondary batteries. Including cycle efficiency, service life, output voltage stability and other aspects have a great impact

[0007] To sum up, as the anode material of lithium secondary battery, metal lithium affects the battery cycle and safety issues due to the existence of dendrites, and graphitized carbon materials affect and limit some large-scale lithium batteries due to their low reversible specific capacity. The advantages of capacity cathode materials, amorphous carbon materials reduce the overall performance of the battery due to severe voltage hysteresis, binary or ternary alloys drastically reduce the life of the battery due to large changes in size and volume during charge and discharge

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