Iron lithium manganese phosphate series particles, and iron lithium manganese phosphate series powder and preparation method therefor

Abstract

Disclosed is iron lithium manganese phosphate series powder. The iron lithium manganese phosphate series powder comprises multiple iron lithium manganese phosphate series particles; each iron lithium manganese phosphate series particle comprises a core part and a shell part; the core part comprises multiple first iron lithium manganese phosphate series nanoparticles which are combined together and have first average grain diameters; and the shell part comprises multiple second iron lithium manganese phosphate series nanoparticles which are combined together and have second average grain diameters, wherein the second average grain diameters are greater than the first average grain diameters. The iron lithium manganese phosphate series powder can be prepared by steps of sequentially performing primary sintering treatment in the temperature range of 300 DEG C-450 DEG C, performing middle sintering treatment in the temperature range of greater than 450 DEG C-600 DEG C and performing final sintering treatment in the temperature range of greater than 600 DEG C-800 DEG C. By taking the iron lithium manganese phosphate series powder as the negative electrode material of the lithium battery, the lithium battery can obtain high energy density and good high-temperature charge-discharge cycling stability and thermal stability.

Description

technical field [0001] The present invention relates to a lithium ferromanganese phosphate powder suitable for use as a cathode material of a lithium battery and a preparation method thereof, in particular to a lithium ferromanganese phosphate comprising a plurality of core-shell shaped lithium manganese iron phosphate particles powder, and the preparation method of the lithium manganese iron phosphate powder. Background technique [0002] At present, the lithium manganese iron phosphate powder used as the cathode material (or positive electrode material) of lithium batteries has not yet reached the stage of commercialization, mainly because the conductivity of the lithium manganese iron phosphate powder itself is low. How to take into account the high energy density and thermal stability of lithium batteries has become the most critical issue. The early technology prepared lithium-manganese-iron-phosphate powder with a lower specific surface area, and the average particle ...

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Problems solved by technology

[0002] At present, the lithium manganese iron phosphate powder used as the cathode material (or positive electrode material) of lithium batteries has not yet reached the stage of commercialization, mainly because the conductivity of the lithium manganese iron phosphate powder itself is low. How to take into account the high energy density and thermal stability of lithium batteries has become the most critical issue

The early technology prepared lithium-manganese-iron-phosphate powder with a lower specific surface area, and the average particle size of its primary particles was greater than 300nm, which could make the thermal stability and charge-discharge cycle stability of lithium batteries meet the market requirements. However, due to the low electrical conductivity of lithium manganese iron phosphate powder, the performance of lithium batteries in terms of energy density and high current discharge capacity is still not ideal

Therefore, in order to improve the electrochemical properties of lithium manganese iron phosphate powder, a few technologies have prepared lithium manganese iron phosphate powder with an average primary particle size of less than 100nm by improving the synthesis method. The distance of bulk electron conduction improves the conductivity of lithium-manganese-iron-phosphate powder. Although this method can effectively improve the capacity and discharge performance of lithium batteries and achieve higher energy density, the lithium-manganese-iron-phosphate particles are nano-sized. It will relatively increase the specific surface area of ​​the lithium manganese iron phosphate powder, resulting in an increase in the reaction area between the cathode and the electrolyte of the lithium battery, making the charge and discharge cycle stability and thermal stability of the lithium battery worse at high temperature

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