Method for preparing lithium vanadium phosphoric acid of anode material of lithium ion battery under high pressure

Abstract

This invention relates to a high-pressure method for preparing vanadium lithium phosphate used as the anode material for lithium ion batteries. The method comprises: (1) mixing lithium salt, vanadium salt and phosphate uniformly, and ball-milling for 7-24 h; (2) preheating in the air at 200-500 deg.C for 2-12 h to obtain vanadium lithium phosphate. The method has such advantages of simple process, abundant raw materials, no need for reductive gas protection during reaction, short reaction time and low reaction temperature. The product has high capacity and good recycling property, and can be used as the anode material for lithium ion batteries.

Description

technical field [0001] The invention relates to a method for preparing a positive electrode material of a battery, in particular to a method for synthesizing a high-performance lithium vanadium phosphate positive electrode material in a high-pressure atmosphere. Background technique [0002] Lithium-ion batteries have many advantages: high working voltage, usually the voltage of a single lithium-ion battery is 3.6V, while the voltage of MH~Ni, Cd~Ni batteries is 1.2V, a difference of 3 times; small size, light weight, specific energy High (specific energy is 3 times that of lead-acid batteries and 2 times that of various nickel batteries); long cycle life, much higher than other batteries; safe and fast charging, low self-discharge rate; no memory effect, long use time. [0003] Therefore, since 1991, when SONY Company introduced commercialized lithium-ion batteries, the research on lithium-ion batteries has been in the ascendant. Currently, most mobile phones, notebook com...

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Problems solved by technology

However, LiMn 2 o 4 There are two main defects: First, the cycle performance is relatively poor, which is mainly attributed to LiMn 2 o 4 During the charge and discharge process, the volume change is large and the Mn 4+ / Mn 3+ John~Teller effect in the conversion process; second, the capacity loss at higher temperature, which is mainly due to the Mn 3+ Disproportionation and Mn 2+ Easily soluble in electrolyte

[0008] However, at present, lithium vanadium phosphate cathode material is only in the initial stage of further research on its structure, and its synthesis and preparation methods have not yet been carried out specific and extensive research work, and there are only a few reports on the synthesis of high-performance lithium vanadium phosphate cathode materials

prepared a lithium vanadium phosphate positive electrode material with excellent cycle performance, but hydrogen was used as a reducing atmosphere during the preparation process, which was relatively expensive, and due to the low diffusion rate of hydrogen, the reaction rate was slow, and large-scale production was difficult.

Huang et al. added carbon glue to the raw materials to form a carbon coating with a nano-network structure in the product, thereby improving the cycle performance and rate performance of the product, but the preparation of carbon glue is difficult and there is no industrialization. products, it is impossible to apply this method to practice

[0009] As far as the current research progress is concerned, there are still no good measures to improve a series of difficulties brought about by low reaction diffusion rate, slow reaction rate, high reaction temperature, and large-scale production difficulties in reducing atmospheres.

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