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Preparation method of high-compaction lithium iron phosphate pole piece

A technology of solid lithium iron phosphate and lithium iron phosphate is applied in the field of preparation of high-pressure solid lithium iron phosphate pole pieces, which can solve the problems of cumbersome process, decreased cycle life, and inability of electrolyte to infiltrate pole pieces.

Pending Publication Date: 2022-03-04
SHANGHAI NAT ENG RES CENT FORNANOTECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the commercial lithium iron phosphate material generally has a compacted density of 2.0-2.5g / cm 3 , if it is further compacted, it will block the pores in the pole piece, and the electrolyte will not be able to infiltrate the pole piece, which seriously limits the performance of the battery, and instead causes a decrease in capacity and a decrease in cycle life
[0004] At present, the synthesis method of high-pressure lithium iron phosphate material has the idea of ​​using spray granulation and then ball milling. This method is cumbersome. In addition, there are lithium iron phosphate materials with large and small particles when stirring the slurry, but the effect is not good. it is good

Method used

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  • Preparation method of high-compaction lithium iron phosphate pole piece
  • Preparation method of high-compaction lithium iron phosphate pole piece

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Experimental program
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Effect test

preparation example Construction

[0025] A preparation method for high-pressure lithium iron phosphate pole piece, as follows:

[0026] 1. Material preparation:

[0027] 1) Nano-sized initial raw materials

[0028] First, 5Kg of lithium carbonate, ferrous sulfate, ammonium dihydrogen phosphate and glucose were wet ball milled for 25 hours to make the average particle size reach 200-500nm, and the obtained nano-scale initial raw material was marked as C, and dried for later use;

[0029] 2) Raw material preprocessing:

[0030] The nanoscale initial raw material C is compacted under the pressure of 1.5MPa and 6MPa respectively, which are respectively marked as A and B; then,

[0031] 3) Put A, B, and C raw materials in a tube furnace respectively, and perform pretreatment at 350°C to obtain pretreated A, B, and C materials as precursors.

Embodiment 1

[0033] A lithium iron phosphate pole piece to be compacted at high pressure, prepared according to the following steps:

[0034] 1) to 3) steps as above;

[0035] 4) Precursor mixing treatment: Take the pretreated A and C materials obtained in step 3) and take the same mass, grind and mix them, put them in a tube furnace, and sinter them at 720°C for 5.5 hours to obtain highly dense iron phosphate Lithium cathode material, marked as A+C;

[0036] 5) Pole sheet preparation: mix the highly dense active material lithium iron phosphate cathode material A+C, the conductive agent and the binder at a mass ratio of 95:3.5:1.5, and prepare the slurry; apply the slurry to a fixed thickness On the aluminum foil, a high-pressure positive electrode sheet with particle size classification and mixed filling of large and small particles is obtained. The thickness is 75 μm. The material is made into an electrode sheet, and the compaction density can reach 2.52g / cm 3 .

[0037] The performan...

Embodiment 2

[0039] A lithium iron phosphate pole piece to be compacted at high pressure, prepared according to the following steps:

[0040] 1) to 3) steps as above;

[0041] 4) Precursor mixing treatment: Take pretreated B and C of equal mass for grinding and mixing, place them in a tube furnace, and sinter at a high temperature of 720°C for 5.5 hours to obtain a highly dense lithium iron phosphate cathode material, marked as B +C;

[0042] 5) Pole sheet preparation: mix the highly dense active material lithium iron phosphate cathode material active material B+C, conductive agent and binder at a mass ratio of 95:3.5:1.5, and mix the slurry; coat the slurry with a fixed thickness On the aluminum foil, a highly compacted positive pole piece is obtained, the thickness of which is 75um, and the compacted density of the pole piece can reach 2.67g / cm 3 .

[0043] The performance test results of the lithium iron phosphate pole piece obtained in this embodiment are shown in Table 1. The spec...

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Abstract

The invention relates to a preparation method of a high-compaction lithium iron phosphate pole piece, a lithium iron phosphate material is composed of large particles and small particles with different sizes, and the preparation method comprises the following steps: nanocrystallization of an initial raw material, pretreatment of the initial material, high-temperature sintering, and mixing and size mixing of a lithium iron phosphate active material, a conductive agent and a binder according to a ratio; and coating an aluminum foil with the slurry according to a fixed thickness to obtain a high-compaction positive pole piece. The method is simple in step operation, easy in condition control and convenient for large-scale production, and the energy density of the battery is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of battery materials, and in particular relates to a preparation method of a high-pressure compacted lithium iron phosphate pole piece. Background technique [0002] At present, lithium iron phosphate is the first choice for commercial batteries because of its excellent safety performance and cycle stability. However, its low energy density greatly limits its application. [0003] In order to further increase the specific energy density of lithium batteries, three ideas are generally adopted: one is to increase the capacity of the active material; the other is to increase the voltage platform; the third is to increase the compaction density of the pole piece. The use of high-pressure compacted lithium iron phosphate material is a good idea, simple and easy to implement, and high in efficiency. At present, the commercial lithium iron phosphate material generally has a compacted density of 2.0-2.5g / cm 3 , i...

Claims

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Application Information

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IPC IPC(8): H01M4/139
CPCH01M4/139Y02E60/10
Inventor 崔大祥王金张芳卢玉英葛美英王亚坤焦靖华张放为
Owner SHANGHAI NAT ENG RES CENT FORNANOTECH
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