Anode active substance, production method thereof, and lithium ion battery employing anode active substance

Abstract

The invention discloses an anode active substance comprising at least one phosphoric acid metal lithium compound and at least one carbon material. The phosphoric acid metal lithium compound has a structural formula of LixMyPO4, wherein M is any transition metal element, x is no smaller than 0 and no larger than 1, and y is no smaller than 0.8 and no larger than 1.2. Also, the invention discloses a production method of the anode active substance and a lithium ion battery employing the anode active substance. According to the invention, with the anode active substance, the diffusion performance of lithium ions can be greatly improved, such that the conductivity of the material can be improved. Therefore, low-resistance improvement can be realized, and negative influences caused by a current carbon cladding method can be avoided. The purity and crystallinity of lithium iron phosphate can be ensured; compaction density and consistency of the material can be improved; and the lithium ion battery employing the anode active substance is provided with good multiplying performance, good low-temperature performance, good high-temperature storing performance, and excellent cyclic performance.

Description

Technical field [0001] The present invention relates to the technical field of batteries, in particular to a positive electrode active material, a production method thereof, and an applied lithium ion battery. Background technique [0002] At present, lithium ion secondary battery is an ideal chemical power source recognized internationally. It has many advantages such as high voltage, high energy density, long cycle life, low self-discharge, no memory effect, wide operating temperature range, and no pollution. It is widely used Used in mobile phones, laptop computers, portable power tools, weaponry, etc. [0003] With the increasing development of lithium-ion batteries, lithium-ion power batteries with large capacity and high rate charging and discharging have also become the focus of competition in various countries around the world. Lithium-ion power batteries will be mainly used in electric vehicles, electric motorcycles, electric bicycles, backup power UPS, military equipmen...

AI Technical Summary

Problems solved by technology

[0006] Although the above three methods can improve the electrochemical performance of lithium iron phosphate to a certain extent, there are certain defects.

For example, the carbon coating method is an effective method in improving the conductivity of lithium iron phosphate powder, but because of the introduction of organic light carbon elements, the relatively small density of lithium iron phosphate powder itself is vibrated and compacted. The density is smaller and the apparent specific surface area is relatively large (mainly affected by light carbon elements), which brings difficulties to the subsequent battery processing procedures. In addition, in large-scale commercial production, the implementation of the carbon coating method is very difficult. The main The difficulty lies in ensuring the uniformity of the coating and the control of the thickness of the coating at the nanometer level. The evaluation test results of a large number of lithium iron phosphate materials show that the carbon coating performance largely determines the stability of material batches

[0007] In addition, the electrical conductivity of the material is improved by doping with metal elements. At present, the mechanism of this method to improve electrical conductivity is not yet clear, and there is a risk that impurities will be mixed in if the doping fails to affect the performance of the battery.

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