Lithium iron phosphate positive pole piece using highly-viscous lithium-conducting binder and preparation method thereof

Abstract

The invention relates to a lithium iron phosphate positive pole piece using a highly-viscous lithium-conducting binder and a preparation method thereof. The lithium iron phosphate positive pole pieceincludes the following components by weight: 90-98 parts of lithium iron phosphate, 1-3 parts of CMC-Li, 0.5-1 part of modified SBR, 0.5-1 part of carbon nanotubes, 0.1-1 part of tea saponin, 1-10 parts of viscosity regulator and 20-60 parts of de-ionized water. The pole piece prepared by the formula of the invention is water-based and environment-friendly, has significantly improved thermal stability, electrical conductivity and electrochemical properties, and has excellent comprehensive performance.

Description

technical field

[0001] The invention relates to the technical field of lithium batteries, in particular to a lithium iron phosphate cathode sheet using a high-viscosity lithium-conducting binder and a preparation method thereof. Background technique

[0002] In recent years, with the continuous development of the domestic electronics industry, people have put forward higher and higher requirements for the energy density of lithium-ion batteries. At present, the key to improving the energy density of lithium-ion batteries lies in the energy density of the cathode material. The existing positive electrode materials that have been marketed include lithium cobaltate, lithium manganate, lithium iron phosphate and ternary materials. In the production process, polyvinylidene fluoride (PVDF) is generally used as a binder. PVDF is not only expensive , in the application process, it is necessary to use explosive and environmentally unfriendly organic solvents, such as N-methylpyrroli...

Examples

preparation example Construction

[0042] 1. The preparation process of CMC-Li adopts the following steps:

[0043] (1) Weigh 10-40 parts of CMC-Na, 30-100 parts of deionized water, 5-20 parts of ethanol with a mass fraction of 80%, 10-30 parts of sulfuric acid solution with a mass fraction of 20%, and a mass fraction of 12 % lithium hydroxide 10~30 parts;

[0044] (2) Dissolve CMC-Na in deionized water, add ethanol, stir fully, and slowly add sulfuric acid solution under stirring, continue to stir, until the reaction is complete, dry to constant weight at 60~80°C to obtain CMC-H ;

[0045] (3) Dissolve CMC-H in a constant temperature water bath at 35-40°C, slowly add lithium hydroxide, continue stirring and filtering, and dry at a temperature of 60-80°C to obtain CMC-Li.

[0046] Two, the preparation process of the viscosity modifier adopts the following steps:

[0047] (1) Ingredients: 30-40 parts of acrylates, 10-15 parts of hydroxyethyl cellulose, 5-10 parts of carbomer, 5-10 parts of xanthan gum and 1-5...

Embodiment 1

[0054] A lithium iron phosphate positive electrode sheet using a high-viscosity lithium-conducting binder is produced by the following method:

[0055] (1) Ingredients: In parts by weight, weigh 90 parts of lithium iron phosphate, 1 part of CMC-Li, 0.5 parts of modified SBR, 0.5 parts of carbon nanotubes, 0.1 parts of tea saponin, 1 part of viscosity modifier and deionized 20 parts of water;

[0056] (2) Mix CMC-Li with deionized water, and add carbon nanotubes and tea saponin during the stirring process to obtain a mixture;

[0057] (3) Under stirring, lithium iron phosphate and modified SBR are added to the mixture to obtain a slurry, and the pH value of the slurry is 7;

[0058] (4) Use a viscosity modifier to adjust the viscosity of the slurry to above 5000mpa s;

[0059] (5) Coating the slurry on the surface of the porous aluminum foil current collector to obtain the positive electrode;

[0060] (6) Dry and sinter, then slice and shape.

Embodiment 2

[0062] The difference from Example 1 is that the component content of the positive electrode material is different and the process parameters are fine-tuned, wherein 92 parts of lithium iron phosphate, 1.5 parts of CMC-Li, 0.6 parts of modified SBR, 0.6 parts of carbon nanotubes, tea soap 0.3 parts of prime, 3 parts of viscosity modifier and 30 parts of deionized water; the pH value of the slurry in step (3) is 7.2.

technical field

[0001] The invention relates to the technical field of lithium batteries, in particular to a lithium iron phosphate cathode sheet using a high-viscosity lithium-conducting binder and a preparation method thereof. Background technique

[0002] In recent years, with the continuous development of the domestic electronics industry, people have put forward higher and higher requirements for the energy density of lithium-ion batteries. At present, the key to improving the energy density of lithium-ion batteries lies in the energy density of the cathode material. The existing positive electrode materials that have been marketed include lithium cobaltate, lithium manganate, lithium iron phosphate and ternary materials. In the production process, polyvinylidene fluoride (PVDF) is generally used as a binder. PVDF is not only expensive , in the application process, it is necessary to use explosive and environmentally unfriendly organic solvents, such as N-methylpyrroli...

Examples

preparation example Construction

[0042] 1. The preparation process of CMC-Li adopts the following steps:

[0043] (1) Weigh 10-40 parts of CMC-Na, 30-100 parts of deionized water, 5-20 parts of ethanol with a mass fraction of 80%, 10-30 parts of sulfuric acid solution with a mass fraction of 20%, and a mass fraction of 12 % lithium hydroxide 10~30 parts;

[0044] (2) Dissolve CMC-Na in deionized water, add ethanol, stir fully, and slowly add sulfuric acid solution under stirring, continue to stir, until the reaction is complete, dry to constant weight at 60~80°C to obtain CMC-H ;

[0045] (3) Dissolve CMC-H in a constant temperature water bath at 35-40°C, slowly add lithium hydroxide, continue stirring and filtering, and dry at a temperature of 60-80°C to obtain CMC-Li.

[0046] Two, the preparation process of the viscosity modifier adopts the following steps:

[0047] (1) Ingredients: 30-40 parts of acrylates, 10-15 parts of hydroxyethyl cellulose, 5-10 parts of carbomer, 5-10 parts of xanthan gum and 1-5...

Embodiment 1

[0054] A lithium iron phosphate positive electrode sheet using a high-viscosity lithium-conducting binder is produced by the following method:

[0055] (1) Ingredients: In parts by weight, weigh 90 parts of lithium iron phosphate, 1 part of CMC-Li, 0.5 parts of modified SBR, 0.5 parts of carbon nanotubes, 0.1 parts of tea saponin, 1 part of viscosity modifier and deionized 20 parts of water;

[0056] (2) Mix CMC-Li with deionized water, and add carbon nanotubes and tea saponin during the stirring process to obtain a mixture;

[0057] (3) Under stirring, lithium iron phosphate and modified SBR are added to the mixture to obtain a slurry, and the pH value of the slurry is 7;

[0058] (4) Use a viscosity modifier to adjust the viscosity of the slurry to above 5000mpa s;

[0059] (5) Coating the slurry on the surface of the porous aluminum foil current collector to obtain the positive electrode;

[0060] (6) Dry and sinter, then slice and shape.

Embodiment 2

[0062] The difference from Example 1 is that the component content of the positive electrode material is different and the process parameters are fine-tuned, wherein 92 parts of lithium iron phosphate, 1.5 parts of CMC-Li, 0.6 parts of modified SBR, 0.6 parts of carbon nanotubes, tea soap 0.3 parts of prime, 3 parts of viscosity modifier and 30 parts of deionized water; the pH value of the slurry in step (3) is 7.2.