WO2018145565A1 - Composite positive electrode material for use in solid-state lithium ion battery and preparation method therefor - Google Patents

Abstract

A composite positive electrode material for use in a solid-state lithium ion battery and a preparation method therefor, the composite positive electrode material comprising a positive electrode active material, a solid electrolyte, and an organic compound additive, wherein the weight ratio between the positive electrode active material, the solid electrolyte and the organic compound additive is 80~88:5~15:2~8. A battery prepared with the composite positive electrode material has an improved energy density. The method for preparing the composite positive electrode material may reduce the interface resistance between the solid electrolyte and the positive electrode material. When the composite positive electrode material obtained by using the method for preparing the composite positive electrode material is used to prepare a solid-state lithium ion battery, a conventional liquid-state lithium ion battery electrodes production line does not need to be altered, thereby greatly lowering the equipment retrofitting cost needed to retrofit a liquid-state lithium ion battery production line for the preparation of solid-state lithium ion batteries.

Description

Composite cathode material for solid lithium ion battery and preparation method thereof Technical field

The invention belongs to the technical field of batteries. In particular, the present invention relates to a positive electrode material for a lithium ion battery and a method of preparing the same, and more particularly to a composite positive electrode material for a solid state lithium ion battery and a method of preparing the same.

Background technique

Lithium-ion battery is a new type of rechargeable battery with high voltage, high energy density, environmental protection and pollution-free. It is known as "the most promising chemical power source". With the rise of the low-carbon economy, lithium-ion batteries are actively developing in the direction of automobile power and grid energy storage.

The traditional structure of the power-type lithium-ion battery has the characteristics of high voltage, high energy density, good cycle performance, etc., and is widely used in portable digital products such as mobile phones, cameras, and notebook computers, and is gradually being applied in the field of electric bicycles, but The use of a flammable and explosive organic carbonate-based electrolyte as an organic electrolyte solution causes electrolyte leakage and the resulting battery explosion, fire, and the like to occur frequently.

An effective way to improve the safety of lithium-ion batteries is to use solid electrolytes, which greatly improve safety while simplifying battery safety devices while reducing costs.

For solid state lithium ion batteries, the interface state between the solid electrolyte and the electrode active material directly affects battery performance. Mainly because the contact between the solid electrolyte and the electrode is not good, the contact resistance between the two is increased, and the internal resistance of the whole battery is too large, and lithium ions cannot move smoothly between the electrode and the electrolyte, thereby reducing The battery capacity also results in lower durability and higher interface resistance.

For an all-solid-state battery, in order to reduce the conduction resistance of internal lithium ions, it is necessary to add 20-30% by weight of a solid electrolyte to be doped into the electrode. The prior art is to mix and coat a ceramic-based or PEO-based solid electrolyte with an active material of an electrode in a certain ratio. This method can reduce the internal resistance of the battery, but since the ceramic-based or PEO-based solid electrolyte can only function as lithium ion conduction, it cannot store lithium ions as an active material, which objectively leads to a decrease in the energy density of the battery.

One of the prior art methods for preparing a solid-state lithium ion battery is to mix and coat a solid electrolyte precursor and a positive electrode active material in a certain ratio, and then to obtain an electrode by high-temperature sintering. The use of a conventional liquid lithium ion battery electrode production line to prepare solid state lithium ion battery electrodes requires the addition of high temperature sintering equipment on this line (see Figure 1).

Another prior art method for preparing a solid-state lithium ion battery is to apply a positive electrode active material and a solid electrolyte layer in a certain ratio according to a certain ratio, press, cut, laminate, etc., and then perform high-temperature sintering after lamination to obtain a desired Solid state lithium ion battery electrode (see Figure 1). This method also needs to increase the high-temperature sintering equipment in the traditional liquid lithium ion electrode production line, and needs to modify the liquid lithium ion battery production line, the cost is high, and the continuity of the original liquid lithium ion battery electrode production line is destroyed.

Therefore, there has been a search in the art for a solid state lithium ion battery having a higher energy density and a method for preparing a solid lithium ion battery electrode without changing the existing liquid lithium ion battery electrode production line.

Summary of the invention

One technical problem to be solved by the present invention is that the existing ceramic-based solid electrolyte can only function as lithium ion conduction, and cannot store lithium ions as an active material, resulting in a decrease in energy density of the battery.

One technical problem to be solved by the present invention is to avoid damage to the continuity of the existing liquid lithium ion battery electrode production line during the preparation of the solid lithium ion battery electrode.

The problem to be solved by the present invention is solved by the following technical solutions:

According to a first aspect of the present invention, a composite positive electrode material for a solid-state lithium ion battery comprising a positive electrode active material, a solid electrolyte, and an organic compound additive, wherein the weight of the positive electrode active material, the solid electrolyte, and the organic compound additive is provided The ratio is 80 to 88:5 to 15:2 to 8.

According to a second aspect of the present invention, there is provided a method of preparing a composite positive electrode material for a solid state lithium ion battery, comprising the steps of:

i) uniformly mixing a solid electrolyte or a precursor thereof with a positive electrode active material or a precursor thereof to obtain a mixture powder;

Ii) The mixture powder is sintered at a high temperature to obtain the composite positive electrode material containing a solid electrolyte and a positive electrode active material in the form of a powder.

According to a third aspect of the invention, there is provided a method of producing a composite positive electrode material of the first aspect of the invention, comprising:

i) uniformly mixing the solid electrolyte or its precursor with the positive electrode active material or its precursor to obtain a mixture powder;

Ii) sintering the obtained mixture powder at a high temperature to obtain a composite powder comprising a solid electrolyte and a positive electrode active material;

Iii) uniformly mixing the obtained composite powder with an organic compound additive to obtain a composite positive electrode material.

According to a fourth aspect of the present invention, a method for preparing a positive electrode of a solid state lithium ion battery, comprising the steps of:

i) using the preparation method described in the second aspect or the third aspect of the invention to prepare a composite positive electrode material;

Ii) The obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is applied onto a positive electrode substrate, dried, compacted, and slit to obtain a positive electrode.

According to a fifth aspect of the invention, there is provided a solid state lithium ion battery positive electrode obtained by the above-described method for producing a solid state lithium ion battery positive electrode.

According to a sixth aspect of the invention, a method of fabricating a solid state lithium ion battery is provided, comprising the steps of:

i) preparing a positive electrode using the preparation method described in the fourth aspect of the invention;

Ii) preparing a negative electrode; and

Iii) The positive electrode and the negative electrode are laminated and assembled with a solid electrolyte to obtain a solid state lithium ion battery.

According to a seventh aspect of the invention, there is provided a solid state lithium ion battery obtained by the above-described method for producing a solid state lithium ion battery.

The invention provides a method for pre-mixing a solid electrolyte and a positive electrode active material and then coating the existing problems in the production method of the existing solid-state lithium ion battery.

The interfacial resistance between the solid electrolyte and the positive electrode material can be reduced by the preparation method of the composite positive electrode material of the present invention. The composite positive electrode material obtained by the preparation method of the composite positive electrode material of the present invention can be used for preparing a solid lithium ion battery without changing the conventional liquid lithium ion battery electrode production line.

The preparation method of the positive electrode of the solid state lithium ion battery of the invention can be carried out without changing the electrode production line of the conventional liquid lithium ion battery, and the equipment transformation cost for preparing the solid lithium ion battery by modifying the liquid lithium ion battery production line can be greatly reduced. The lithium ion of the solid electrolyte of the solid-state lithium ion battery of the present invention has high conductivity, low internal resistance, and good rate discharge performance.

The invention also improves the energy density of the solid state lithium ion battery by mixing the active material or the precursor material of the electrode with the organic compound having the lithium ion storage ability and a small amount of the solid electrolyte to prepare the electrode.

The preparation method of the composite positive electrode material of the present invention is not limited to the preparation of the positive electrode material of the solid lithium ion battery, and can also be used for the preparation of the positive electrode material of the sodium ion battery, as long as the corresponding solid electrolyte or its precursor and the positive electrode active material or The precursor can be replaced. Also, the preparation method of the positive electrode of the solid state lithium ion battery of the present invention and the preparation method of the solid state lithium ion battery are also the same.

DRAWINGS

1 schematically shows a method of preparing a conventional solid state lithium ion battery, wherein sintering is optionally performed before or prior to rolling.

Fig. 2 schematically shows a method of preparing a solid state lithium ion battery of the present invention, in which a conventional liquid lithium ion battery production line is shown in a dotted line.

Specific implementation

The technical solution of the present invention will be described in detail below.

According to a first aspect of the present invention, a composite positive electrode material for a solid-state lithium ion battery comprising a positive electrode active material, a solid electrolyte, and an organic compound additive, wherein the weight of the positive electrode active material, the solid electrolyte, and the organic compound additive is provided The ratio is 80 to 88:5 to 15:2 to 8.

The positive active material may be a solid cathode active material commonly used in solid lithium ion batteries in the field, such as lithium cobaltate, lithium manganate, nickel manganese material, lithium iron phosphate, nickel cobalt manganese, nickel cobalt aluminum ternary material, and Sulfur-containing materials. The nickel manganese material may be LiNi _0.5 Mn _1.5 O ₄ , LiNi _0.5 Mn _0.5 O ₂ or the like. The sulfur-containing material may be S, Li ₂ S, or the like.

The solid electrolyte may be a solid electrolyte material commonly used in solid state lithium ion batteries in the art, such as NASICON type lithium ion conductor Li _1+x Ti _2-x M _x (PO ₄ ) ₃ , Li _1+x Ge _2-x M _x (PO ₄ ) ₃ (0.1<x<0.7, M=Al, Ga, In, Sc); perovskite-type lithium ion conductor Li _3x La _(2/3)-x TiO ₃ (0<x<0.16) LISICON type lithium ion conductor Li ₁₄ ZnGe ₄ O ₁₆ ; garnet type lithium ion conductor Li ₅ La ₃ M ₂ O ₁₂ (M=Ta, Nb), Li ₇ La ₃ Zr ₂ O ₁₂ ; glass ceramic electrolyte Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₇ P ₃ S ₁₁ , Li ₁₀ GeP ₂ S ₁₂ and the like.

The organic compound additive may be selected, for example, from a metal organic framework material (MOF), an oxygen-containing conjugated organic substance, a conductive high molecular weight, an organic sulfide, and the like.

As examples of the oxygen-containing conjugated organic compound, mention may be made of 1,4,5,8-tetrahydroxy-9,10-fluorene (THAQ), tetrahydrohexafluorene (THHQ), and benzohexacene (DBHQ). ), 2,4,7-trinitro-9-fluorenone (TNF), and the like.

As examples of the conductive polymer, polyacetylene, polyparaphenylene, polyaniline, polypyrrole, polythiophene and the like can be mentioned.

As examples of the organic sulfide, mention may be made of poly 2,5-dimercapto-thiadiazole, poly 2,2-dithiodiphenyl (PDTDA), 14-phenylene-1, 2, 4 - Dithiazole polymer (PPDTA) or the like.

The weight ratio of the positive electrode active material, the solid electrolyte, and the organic compound additive is preferably 82 to 87:8 to 12:3 to 6.

In one embodiment, the weight ratio of the positive active material, the solid electrolyte, and the organic compound additive is 85:10:5.

According to a second aspect of the present invention, there is provided a method of preparing a composite positive electrode material for a solid state lithium ion battery, comprising the steps of:

i) uniformly mixing a solid electrolyte or a precursor thereof with a positive electrode active material or a precursor thereof to obtain a mixture powder;

Ii) The mixture powder is sintered at a high temperature to obtain a composite positive electrode material comprising a solid electrolyte and a positive electrode active material in the form of a powder.

The preparation method according to the second aspect of the invention may further comprise the following steps:

Iii) uniformly mixing the composite powder containing the solid electrolyte and the positive electrode active material with the organic compound additive to obtain a composite positive electrode material, wherein the weight ratio of the positive electrode active material, the solid electrolyte and the organic compound additive is 80 to 88:5 to 15:2. 8.

In the composite positive electrode material, the solid electrolyte is contained in an amount of from 5% by weight to 40% by weight, preferably from 10% by weight to 30% by weight, more preferably from 15% by weight to 25% by weight, most preferably from 18% by weight to 22% by weight. The weight is based on the total weight of the composite positive electrode material.

The solid electrolyte may be a solid electrolyte material commonly used in solid state lithium ion batteries in the art, such as NASICON type lithium ion conductor Li _1+x Ti _2-x M _x (PO ₄ ) ₃ , Li _1+x Ge _2-x M _x (PO ₄ ) ₃ (0.1<x<0.7, M=Al, Ga, In, Sc); perovskite-type lithium ion conductor Li _3x La _(2/3)-x TiO ₃ (0<x<0.16) LISICON type lithium ion conductor Li ₁₄ ZnGe ₄ O ₁₆ ; garnet type lithium ion conductor Li ₅ La ₃ M ₂ O ₁₂ (M=Ta, Nb), Li ₇ La ₃ Zr ₂ O ₁₂ ; glass ceramic electrolyte Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₇ P ₃ S ₁₁ , Li ₁₀ GeP ₂ S ₁₂ and the like.

Those skilled in the art will readily be able to determine the precursor of the solid electrolyte based on the desired solid electrolyte. For example, when the solid electrolyte is Li _1.52 Al _0.5 Ge _1.5 P ₃ O _12.01 , for example, Li ₂ CO ₃ , Al(OH) ₃ , GeO _{2 ,} and NH ₄ H ₂ PO _{4 may be selected} as the solid electrolyte precursor. When the solid electrolyte is Li ₇ La ₃ Zr ₂ O ₁₂ , for example, lithium acetate, cerium acetate, and zirconium acetate can be selected as the solid electrolyte precursor.

The positive active material may be a solid cathode active material commonly used in solid lithium ion batteries in the field, such as lithium cobaltate, lithium manganate, nickel manganese material, lithium iron phosphate, nickel cobalt manganese, nickel cobalt aluminum ternary material, and Sulfur-containing materials. The nickel manganese material may be LiNi _0.5 Mn _1.5 O ₄ , LiNi _0.5 Mn _0.5 O ₂ or the like. The sulfur-containing material may be S, Li ₂ S, or the like.

A person skilled in the art can easily determine the precursor of the positive active material from the desired positive active material.

The homogeneous mixing of the solid electrolyte or its precursor with the positive electrode active material or its precursor can be carried out by a mechanical mixing method commonly used in the art, such as high speed ball milling, and the obtained powder has an average particle diameter of 30 to 900 nm, preferably 50 to 500 nm. More preferably, it is 80-150 nm.

The sintering is carried out at 300 ° C to 1200 ° C, preferably 500 ° C to 1150 ° C, more preferably 600 ° C to 1150 ° C, most preferably 750 ° C to 1125 ° C for 8 to 24 hours, preferably 10 to 12 hours, more preferably 12 hours.

In one embodiment, the sintering process can be carried out as follows: ramping to 750 ° C at 5 ° C/min and holding at 750 ° C for 12 h.

In one embodiment, the sintering process can be carried out as follows: 5 ° C / min to 900 ° C, 8 ° h at 900 ° C and then warmed to 1125 ° C and then kept at 1125 ° C for 12 h.

When the precursor powder is contained in the mixture powder, the precursor reacts during the sintering to obtain a solid electrolyte or a positive electrode active material.

The positive active material is activated during the sintering process.

According to a third aspect of the invention, there is provided a method of producing a composite positive electrode material of the first aspect of the invention, comprising:

i) uniformly mixing the solid electrolyte or its precursor with the positive electrode active material or its precursor to obtain a mixture powder;

Ii) sintering the obtained mixture powder at a high temperature to obtain a composite powder comprising a solid electrolyte and a positive electrode active material;

Iii) uniformly mixing the obtained composite powder with an organic compound additive to obtain a composite positive electrode material.

Those skilled in the art will readily be able to determine the precursor of the solid electrolyte based on the desired solid electrolyte. For example, when the solid electrolyte is Li _1.52 Al _0.5 Ge _1.5 P ₃ O _12.01 , for example, Li ₂ CO ₃ , Al(OH) ₃ , GeO _{2 ,} and NH ₄ H ₂ PO _{4 may be selected} as the solid electrolyte precursor. When the solid electrolyte is Li ₇ La ₃ Zr ₂ O ₁₂ , for example, lithium acetate, cerium acetate, and zirconium acetate can be selected as the solid electrolyte precursor.

A person skilled in the art can easily determine the precursor of the positive active material from the desired positive active material.

The homogeneous mixing of the solid electrolyte or its precursor with the positive electrode active material or its precursor can be carried out by a mechanical mixing method commonly used in the art, such as high speed ball milling, and the obtained powder has an average particle diameter of 30 to 900 nm, preferably 50 to 500 nm. More preferably, it is 80-150 nm.

The sintering is carried out at 300 ° C to 1200 ° C, preferably 500 ° C to 1150 ° C, more preferably 600 ° C to 1150 ° C, for 8 to 24 hours, preferably 10 to 12 hours, more preferably 12 hours.

In one embodiment, the sintering process can be carried out as follows: ramping to 600 ° C at 5 ° C/min and holding at 600 ° C for 12 h.

In one embodiment, the sintering process can be carried out as follows: ramping to 1125 ° C at 5 ° C/min and holding at 1125 ° C for 12 h.

When the precursor powder is contained in the mixture powder, the precursor reacts during the sintering to obtain a solid electrolyte or a positive electrode active material.

The positive active material is activated during the sintering process.

According to a fourth aspect of the present invention, a method for preparing a positive electrode of a solid state lithium ion battery, comprising the steps of:

i) using the preparation method described in the second aspect or the third aspect of the invention to prepare a composite positive electrode material;

Ii) The obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is applied onto a positive electrode substrate, dried, compacted, and slit to obtain a positive electrode.

According to one embodiment, a solid state lithium ion battery positive electrode is prepared as follows:

a) uniformly mixing a solid electrolyte or a precursor thereof with a positive electrode active material or a precursor thereof to obtain a mixture powder;

b) sintering the mixture powder at a high temperature to obtain a composite positive electrode material comprising a solid electrolyte and a positive electrode active material in powder form;

c) The obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is applied onto a positive electrode substrate, and dried, rolled, and slit to obtain a positive electrode.

According to another embodiment, a solid state lithium ion battery positive electrode is prepared as follows:

a) uniformly mixing the solid electrolyte or its precursor with the positive electrode active material or its precursor to obtain a mixture powder;

b) sintering the obtained mixture powder at a high temperature to obtain a composite powder comprising a solid electrolyte and a positive electrode active material;

c) uniformly mixing the obtained composite powder with an organic compound additive to obtain a composite positive electrode material;

d) The obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is applied onto a positive electrode substrate, and dried, rolled, and slit to obtain a positive electrode.

The positive electrode slurry can be formulated by dissolving or dispersing a composite positive electrode material, a conductive additive, and a binder in a solvent.

In one embodiment, the positive electrode slurry is formulated by mixing a composite positive electrode material, a conductive additive, and a binder, and dissolving or dispersing the resulting mixture in a solvent.

The conductive additive may be a conductive additive commonly used in the field of lithium ion battery preparation, such as graphite conductive agent, such as KS-6, KS-15, SFG-6, SFG-15; carbon black conductive agent, such as acetylene black, Super P Super S, 350G, carbon fiber (VGCF, carbon nanotube (CNT), Ketjen black; graphene, etc.

The binder may be a binder commonly used in the field of lithium ion battery preparation, such as polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose. (CMC) and so on.

The solvent may be a solvent commonly used in the field of lithium ion battery preparation, such as N-methylpyrrolidone (NMP) and the like.

Those skilled in the art will readily formulate the amount of composite positive electrode material, conductive additive and binder as desired.

In one embodiment, the mass ratio of the composite positive electrode material, the conductive additive, and the binder is from 80 to 90:5 to 10:5 to 10, preferably from 85 to 90:5 to 8:5 to 8.

In one embodiment, the mass ratio of the composite positive electrode material, the conductive additive, and the binder is 88:6:6.

In one embodiment, the mass ratio of the composite positive electrode material, the conductive additive, and the binder is 90:5:5.

The positive electrode substrate is a positive electrode substrate commonly used in solid state lithium ion batteries, such as aluminum foil.

Coating, drying, rolling, and slitting in the preparation of the positive electrode can be carried out according to process parameters known in the art.

For example, the drying may be carried out by constant temperature heating drying, rotary evaporation drying or spray drying.

For example, the rolling may be performed by rolling at a pressure of 5 MPa.

According to a fifth aspect of the invention, there is provided a solid state lithium ion battery positive electrode obtained by the above-described method for producing a solid state lithium ion battery positive electrode.

According to a sixth aspect of the invention, a method of fabricating a solid state lithium ion battery is provided, comprising the steps of:

i) preparing a positive electrode using the preparation method described in the fourth aspect of the invention;

Ii) preparing a negative electrode; and

Iii) The positive electrode and the negative electrode are laminated and assembled with a solid electrolyte to obtain a solid state lithium ion battery.

According to one embodiment, a solid state lithium ion battery is prepared as follows:

a) uniformly mixing a solid electrolyte or a precursor thereof with a positive electrode active material or a precursor thereof to obtain a mixture powder;

b) sintering the mixture powder at a high temperature to obtain a composite positive electrode material comprising a solid electrolyte and a positive electrode active material in powder form;

c) the obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is coated on a positive electrode substrate, and dried, rolled, and slit to obtain a positive electrode;

d) preparing a negative electrode; and

e) The positive electrode and the negative electrode are laminated and assembled with a solid electrolyte to obtain a solid state lithium ion battery.

According to another embodiment, a solid state lithium ion battery is prepared as follows:

a) uniformly mixing the solid electrolyte or its precursor with the positive electrode active material or its precursor to obtain a mixture powder;

b) sintering the obtained mixture powder at a high temperature to obtain a composite powder comprising a solid electrolyte and a positive electrode active material;

c) uniformly mixing the obtained composite powder with an organic compound additive to obtain a composite positive electrode material;

d) the obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is coated on a positive electrode substrate, and dried, rolled, and slit to obtain a positive electrode;

e) preparing a negative electrode; and

f) The positive electrode and the negative electrode are laminated and assembled with a solid electrolyte to obtain a solid state lithium ion battery.

Those skilled in the art can understand that the step of obtaining the positive electrode and the step of obtaining the negative electrode are not successively required, and the positive electrode may be prepared first, or the negative electrode may be prepared first, or the positive electrode and the negative electrode may be simultaneously prepared.

The method of preparing the negative electrode is a method generally used in the art. The negative electrode material is a negative electrode material commonly used in solid lithium ion batteries, such as graphite, lithium titanate, metallic lithium, and the like.

For example, a sheet of a metal material can be directly used as a negative electrode.

The negative electrode material may also be formulated into a negative electrode slurry, and the obtained negative electrode slurry may be applied onto a negative electrode substrate, dried, rolled, and slit to obtain a negative electrode.

The negative electrode slurry is prepared by dissolving or dispersing a negative electrode material, a conductive additive, and a binder in a solvent.

In one embodiment, the anode slurry is formulated as follows: a negative electrode material, a conductive additive, and a binder are mixed, and the resulting mixture is dissolved or dispersed in a solvent.

The conductive additive may be a conductive additive commonly used in the field of lithium ion battery preparation, such as graphite conductive agent, such as KS-6, KS-15, SFG-6, SFG-15; carbon black conductive agent, such as acetylene black, Super P , Super S, 350G, carbon fiber (VGCF), carbon nanotubes (CNT), Ketjen black; graphene and the like.

The binder may be a binder commonly used in the field of lithium ion battery preparation, such as polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose. (CMC) and so on.

The solvent may be a solvent commonly used in the field of lithium ion battery preparation, such as N-methylpyrrolidone (NMP) and the like.

Those skilled in the art will readily formulate the amount of negative electrode material, conductive additive and binder as desired.

In one embodiment, the mass ratio of the anode material, the conductive additive, and the binder is from 80 to 95:5 to 10:5 to 10, preferably from 85 to 90:1 to 5:5 to 10.

In one embodiment, the mass ratio of the anode material, the conductive additive, and the binder is 90:1:9.

The negative electrode substrate is a negative electrode substrate commonly used in solid state lithium ion batteries, such as copper foil.

The solid electrolyte is the same as the solid electrolyte described in the first aspect of the invention.

The lamination, assembly, drying, rolling, slitting, and lamination, assembly of the slurry during the preparation of the negative electrode can be carried out according to process parameters known in the art.

For example, the drying may be carried out by constant temperature heating drying, rotary evaporation drying or spray drying.

For example, the rolling may be performed by rolling at a pressure of 5 MPa.

In the prior art described in FIG. 1, it is necessary to increase the high-temperature sintering step (dashed box in FIG. 1) after coating drying or lamination to modify the conventional liquid lithium ion battery production line, thereby destroying continuity and increasing The cost.

Fig. 2 schematically shows a method of preparing a solid state lithium ion battery of the present invention, which does not require a change in a liquid lithium ion battery production line.

The present invention avoids damage to the continuity of existing liquid lithium ion battery production lines by forming an activated positive electrode material prior to coating.

According to a seventh aspect of the invention, there is provided a solid state lithium ion battery obtained by the above-described method for producing a solid state lithium ion battery.

The solid lithium ion battery according to the present invention can have a higher energy density.

The word "comprising" and "comprising", as used in the specification of the present application, encompasses the singular and s

The concept and the resulting technical effects of the present invention will be further described in conjunction with the embodiments and the accompanying drawings.

Example

Some of the raw materials used in the examples are as follows:

Super P: graphite conductive additive;

KS-6: carbon black conductive additive;

PVDF: binder, polyvinylidene fluoride;

NMP: solvent, N-methylpyrrolidone.

Example 1

A NASICON type lithium ion conductor was selected as the solid electrolyte, LiCoO _{2 was} used as the positive electrode material, and the solid electrolyte precursor powder (Li ₂ CO ₃ :Al(OH) ₃ :GeO ₂ : was weighed according to the mass ratio of the solid electrolyte to the positive electrode material of 15:85, respectively. NH ₄ H ₂ PO _{4 is} in accordance with Li _1.52 Al _0.5 Ge _1.5 P ₃ O _12.01 stoichiometric ratio) and LiCoO ₂ powder. The mixed powder was ball milled using a planetary ball mill at a speed of 400 r/min and ball milled for 24 hours. The powder mixture obtained by ball milling was transferred to Al ₂ O ₃ crucible, and the crucible was placed in a muffle furnace, and the temperature was raised to 750 ° C at 5 ° C / min, and the composite positive electrode having a particle diameter of 100 nm was obtained after being kept at 750 ° C for 12 h. Material powder.

According to the composite positive electrode material: Super P: KS-6: PVDF = 88: 4: 2: 6 mass ratio, the composite positive electrode material, Super P, KS-6 and PVDF were mixed to obtain 10 g of a mixture, and the mixture was dispersed in 5 g of NMP. In the middle, the mixture was uniformly stirred by a vacuum planetary mixer to obtain a positive electrode slurry. The positive electrode slurry was coated on an aluminum foil having a thickness of 18 μm to a coating thickness of 60 μm. Further, drying was carried out in a vacuum oven at 80 ° C for 24 hours, and the dried electrode sheet was rolled (pressure controlled at 5 MPa), and the solid electrolyte composite positive electrode sheet was obtained by slitting.

Graphite, Super P and PVDF were mixed in a mass ratio of graphite:Super P:PVDF=90:1:9 to obtain 11 g of a mixture, and the mixture was dispersed in 8.25 g of NMP, and thoroughly stirred by a vacuum planetary mixer. The negative electrode slurry was obtained, and the negative electrode slurry was applied on a copper foil having a thickness of 12 μm to a coating thickness of 65 μm. The mixture was further dried in a vacuum oven at 80 ° C for 24 hours, rolled (pressure controlled at 5 MPa), and slit-cut to obtain a negative electrode sheet.

The obtained positive and negative electrode sheets were laminated and assembled with a Li _1.52 Al _0.5 Ge _1.5 P ₃ O _12.01 solid electrolyte to obtain a solid lithium ion battery. The solid state lithium ion battery was discharged at 25 ° C, 0.5 C for 1 C, and the charge and discharge cycle test was carried out under the conditions of a charge and discharge cutoff voltage of 4.2 V - 2.5 V. The results showed that the first discharge specific capacity was 130 mAh / g, after 100 cycles. The capacity retention rate is 87%, and the degree of decline is small.

Example 2

A NASICON type lithium ion conductor was selected as the solid electrolyte, and LiCoO _{2 was} used as the positive electrode material, and the solid electrolytes Li _1.52 Al _0.5 Ge _1.5 P ₃ O _12.01 and LiCoO ₂ powder were weighed according to the mass ratio of the solid electrolyte and the positive electrode material of 15:85, respectively. The mixed powder was ball milled using a planetary ball mill at a speed of 400 r/min and ball milled for 24 hours. The ball-milled mixed powder was transferred to Al ₂ O ₃ crucible, and the crucible was placed in a muffle furnace, and the temperature was raised to 750 ° C at 5 ° C / min, and the composite positive electrode having a particle diameter of 90 nm was obtained after being kept at 750 ° C for 12 h. Material powder.

According to the composite positive electrode material: Super P: KS-6: PVDF = 88: 4: 2: 6 mass ratio, the composite positive electrode material, Super P, KS-6 and PVDF were mixed to obtain 10 g of a mixture, and the mixture was dispersed in 5 g of NMP. In the middle, the mixture was uniformly stirred by a vacuum planetary mixer to obtain a positive electrode slurry. The positive electrode slurry was coated on an aluminum foil having a thickness of 18 μm to a coating thickness of 60 μm. Further, drying was carried out in a vacuum oven at 80 ° C for 24 hours, and the dried electrode sheet was rolled (pressure controlled at 5 MPa), and the solid electrolyte composite positive electrode sheet was obtained by slitting.

Graphite, Super P and PVDF were mixed in a mass ratio of graphite:Super P:PVDF=90:1:9 to obtain 11 g of the mixture. The mixture was dispersed in 8.25 g of NMP and thoroughly stirred by a vacuum planetary mixer. The negative electrode slurry was obtained, and the negative electrode slurry was coated on a copper foil having a thickness of 12 μm to a coating thickness of 65 μm. The mixture was further dried in a vacuum oven at 80 ° C for 24 hours, rolled (pressure controlled at 5 MPa), and slit-cut to obtain a negative electrode sheet.

The obtained positive and negative electrode sheets were laminated and assembled with a Li _1.52 Al _0.5 Ge _1.5 P ₃ O _12.01 solid electrolyte to obtain a solid lithium ion battery. The solid-state lithium ion battery was charged and discharged at 25 ° C, 0.5 C for 1 C discharge, and the charge-discharge cut-off voltage was 4.2 V-2.5 V. The results showed that the first discharge specific capacity was 128 mAh/g, after 100 cycles, The capacity retention rate is 85%, and the degree of decline is small.

Example 3

Lithium-ion lithium ion conductor Li ₇ La ₃ Zr ₂ O _{12 was selected} as the solid electrolyte, LiFePO _{4 was} used as the positive electrode material, and the solid electrolyte Li ₇ La ₃ Zr ₂ O ₁₂ and the mass ratio of the solid electrolyte and the positive electrode material were respectively 20:80. LiFePO ₄ powder. The mixed powder was ball milled using a planetary ball mill at a speed of 400 r/min and ball milled for 24 hours. The ball-milled mixed powder was transferred to Al ₂ O ₃ crucible, and the crucible was placed in a muffle furnace, and the temperature was raised to 1125 ° C at 5 ° C / min, and the composite positive electrode having a particle diameter of 95 nm was obtained after being kept at 1125 ° C for 12 h. Material powder.

According to the composite positive electrode material: Super P: KS-6: PVDF = 90:3:2:5 mass ratio, the composite positive electrode material, Super P, KS-6 and PVDF were mixed to obtain 10 g of the mixture, and the mixture was dispersed in 5 g of NMP. In the middle, the mixture was uniformly stirred by a vacuum planetary mixer to obtain a positive electrode slurry. The positive electrode slurry was coated on an aluminum foil having a thickness of 18 μm to a coating thickness of 60 μm. Further, drying was carried out in a vacuum oven at 80 ° C for 24 hours, and the dried electrode sheet was rolled (pressure controlled at 5 MPa), and the solid electrolyte positive electrode sheet was obtained by slitting.

Graphite, Super P and PVDF were mixed in a mass ratio of graphite:Super P:PVDF=90:1:9 to obtain 11 g of a mixture, and the mixture was dispersed in 8.25 g of NMP, and thoroughly stirred by a vacuum planetary mixer. The negative electrode slurry was obtained, and the negative electrode slurry was applied on a copper foil having a thickness of 12 μm to a coating thickness of 65 μm. The mixture was further dried in a vacuum oven at 80 ° C for 24 hours, rolled (pressure controlled at 5 MPa), and slit-cut to obtain a negative electrode sheet.

The obtained positive and negative electrode sheets were laminated and assembled with a Li ₇ La ₃ Zr ₂ O ₁₂ solid electrolyte to obtain a solid lithium ion battery. The solid-state lithium ion battery was subjected to a charge-discharge cycle test at 25 ° C, 0.5 C charge 1 C discharge, charge and discharge cut-off voltage 3.7 V-2.2 V, and the results showed that the first discharge specific capacity was 120 mAh / g, after 100 cycles, The capacity retention rate is 87%, and the degree of decline is small.

Example 4

Lithium-ion lithium ion conductor Li ₇ La ₃ Zr ₂ O _{12 was selected} as the solid electrolyte, and LiFePO _{4 was} used as the positive electrode material. The solid electrolyte precursor powder was weighed according to the mass ratio of the solid electrolyte and the positive electrode material of 20:80 (lithium acetate: barium acetate) : Zirconium acetate is weighed according to the Li ₇ La ₃ Zr ₂ O ₁₂ stoichiometric ratio) and LiFePO ₄ powder. The mixed powder was ball milled using a planetary ball mill at a speed of 400 r/min and ball milled for 24 hours. The ball-milled mixed powder is transferred to Al ₂ O ₃ crucible, and the crucible is placed in a muffle furnace, first heated to 900 ° C at 5 ° C / min, held at 900 ° C for 8 h and then heated to 1125 ° C and then at 1125 After heating at ° C for 12 h, a composite positive electrode material powder having a particle diameter of 100 nm was obtained.

According to the composite positive electrode material: Super P: KS-6: PVDF = 90:3:2:5 mass ratio, the composite positive electrode material, Super P, KS-6 and PVDF were mixed to obtain 10 g of the mixture, and the mixture was dispersed in 5 g of NMP. In the middle, the mixture was uniformly stirred by a vacuum planetary mixer to obtain a positive electrode slurry. The positive electrode slurry was coated on an aluminum foil having a thickness of 18 μm to a coating thickness of 60 μm. Further, drying was carried out in a vacuum oven at 80 ° C for 24 hours, and the dried electrode sheet was rolled (pressure controlled at 5 MPa), and the solid electrolyte composite positive electrode sheet was obtained by slitting.

Graphite, Super P and PVDF were mixed in a mass ratio of graphite:Super P:PVDF=90:1:9 to obtain 11 g of a mixture, and the mixture was dispersed in 8.25 g of NMP, and thoroughly stirred by a vacuum planetary mixer. The negative electrode slurry was obtained, and the negative electrode slurry was applied on a copper foil having a thickness of 12 μm to a coating thickness of 65 μm. The mixture was further dried in a vacuum oven at 80 ° C for 24 hours, rolled (pressure controlled at 5 MPa), and slit-cut to obtain a negative electrode sheet.

The obtained positive and negative electrode sheets were laminated and assembled with a Li ₇ La ₃ Zr ₂ O ₁₂ solid electrolyte to obtain a solid lithium ion battery. The solid-state lithium ion battery was subjected to charge and discharge cycle test at 25 ° C, 0.5 C charge 1 C discharge, charge and discharge cut-off voltage 3.7 V-2.2 V, and the results showed that the first discharge specific capacity was 118 mAh / g, after 100 cycles, The capacity retention rate is 87%, and the degree of decline is small.

Example 5

Lithium cobaltate was used as the electrode active material, and NASICON lithium ion conductor LiTi ₂ (PO4) _{3 was} used as the solid electrolyte. Prussian blue Fe(III) ₄ [Fe(II)(CN) ₆ ] ₃ ·14H ₂ O was selected as the organic substance. Add material. According to lithium cobaltate: Fe(III) ₄ [Fe(II)(CN) ₆ ] ₃ ·14H ₂ O:LiTi ₂ (PO ₄ ) ₃ =85:10:5 weigh 0.5g of lithium cobaltate, 0.0588 g of Fe(III) ₄ [Fe(II)(CN) ₆ ] ₃ ·14H ₂ O and 0.0294 g of LiTi ₂ (PO ₄ ) _{3 were used} . Lithium cobaltate and LiTi ₂ (PO ₄ ) ₃ were first ball milled uniformly in a planetary ball mill (rotation speed 400 r/min, ball milling 24 h). The mixed powder after the ball milling was uniformly transferred to Al ₂ O ₃ crucible, the crucible was placed in a muffle furnace, and the temperature was raised to 600 ° C at 5 ° C / min, and the composite powder was obtained by holding at 600 ° C for 12 h. The composite powder was then ball milled with a weighed amount of Fe(III) ₄ [Fe(II)(CN) ₆ ] ₃ ·14H ₂ O (rotation speed 400 r/min, ball milling for 24 h). Finally, the mixed powder after the ball milling was uniform was kept in an oven at 150 ° C for 12 hours to obtain a composite positive electrode material having a particle diameter of 100 nm.

According to the composite positive electrode material: Super P: KS-6: PVDF = 88: 4: 2: 6 mass ratio, the composite positive electrode material, Super P, KS-6 and PVDF were mixed to obtain 0.65 g of a mixture, which was dispersed in 0.32 g of NMP solvent. The mixture was thoroughly stirred with a vacuum planetary mixer to obtain a positive electrode slurry. The slurry was coated on an aluminum foil (thickness 65 μm) to a thickness of 100 μm. After drying in an oven at 80 ° C for 24 hours, the dried electrode sheets were rolled (pressure controlled at 5 MPa), and the positive electrode sheets were obtained by slitting.

A lithium metal plate was used as a negative electrode sheet, and the obtained positive electrode sheet and negative electrode sheet were laminated with LiTi ₂ (PO ₄ ) ₃ as a solid electrolyte, and assembled into a battery to obtain a solid lithium ion battery. The obtained solid-state lithium ion battery was charged and discharged at 25 ° C and 0.2 C, and the first discharge specific capacity was 127 mAh/g, which was higher than that of the general lithium cobaltate positive electrode solid battery. After 50 cycles of 0.2 C charge and discharge cycle, the capacity retention rate was 84%.

Compared with Comparative Example 1, the specific capacity of the solid lithium ion battery obtained by using the composite positive electrode material having the organic additive was significantly higher than that of the solid lithium ion battery obtained by using the composite positive electrode material without the organic additive.

Example 6

Lithium cobaltate was used as the electrode active material, and garnet-type lithium ion conductor Li ₇ La ₃ Zr ₂ O _{12 was} used as the solid electrolyte, and bismuth hexafluorene (DBHQ) was selected as the organic additive material.

According to lithium cobaltate: benzobenzopyrene: Li ₇ La ₃ Zr ₂ O ₁₂ =85:10:5 weigh 0.5g of lithium cobaltate, 0.0588g of indolobenzine and 0.0294g of Li ₇ La ₃ Zr ₂ O ₁₂ spare. Lithium cobaltate and Li ₇ La ₃ Zr ₂ O ₁₂ were first ball milled uniformly in a planetary ball mill (rotation speed 400 r/min, ball milling 24 h). The mixed powder after the ball milling was uniformly transferred to Al ₂ O ₃ crucible, and the crucible was placed in a muffle furnace, and the temperature was raised to 1125 ° C at 5 ° C / min, and the composite powder was obtained by holding at 1125 ° C for 12 h. The composite powder was then ball milled with a weighed bismuthene hexafluorene (rotation speed 400 r/min, ball milling for 24 h). Finally, the ball-milled mixed powder was incubated in an oven at 150 ° C for 12 h to obtain a composite positive electrode material having a particle diameter of 100 nm.

According to the composite positive electrode material: Super P: KS-6: PVDF = 88: 4: 2: 6 mass ratio, the composite positive electrode material, Super P, KS-6 and PVDF were mixed to obtain 0.65 g of a mixture, which was dispersed in 0.32 g of NMP solvent. The mixture was thoroughly stirred with a vacuum planetary mixer to obtain a positive electrode slurry. The slurry was coated on an aluminum foil (thickness 65 μm) to a thickness of 100 μm. After drying in an oven at 80 ° C for 24 hours, the positive electrode sheets were obtained by slitting.

A lithium metal sheet was used as a negative electrode sheet, and the obtained positive electrode sheet and negative electrode sheet were laminated with Li ₇ La ₃ Zr ₂ O ₁₂ as a solid electrolyte, and assembled into a battery to obtain a solid lithium ion battery. The obtained solid-state lithium ion battery was charged and discharged at 25 ° C and 0.2 C, and the first discharge specific capacity was 130 mAh/g, which was higher than that of the general lithium cobaltate positive electrode solid battery. After 50 weeks of the 0.2 C charge and discharge cycle, the capacity retention rate was 89%.

While some aspects of the present invention have been shown and described, it will be understood by those skilled in the <RTIgt; Equivalent content is limited.

Claims (14)

1. A composite positive electrode material for a solid-state lithium ion battery, comprising: a positive electrode active material, a solid electrolyte, and an organic compound additive, wherein the weight ratio of the positive electrode active material, the solid electrolyte, and the organic compound additive is 80 to 88 : 5 ~ 15: 2 ~ 8.
2. The composite positive electrode material according to claim 1, wherein the solid electrolyte is selected from the group consisting of NASICON type lithium ion conductors Li _1+x Ti _2-x M _x (PO ₄ ) ₃ , Li _1+x Ge _2-x M _x (PO ₄ ) ₃ , wherein 0.1<x<0.7, M=Al, Ga, In, Sc; perovskite-type lithium ion conductor Li _3x La _(2/3)-x TiO ₃ , where 0<x<0.16; LISICON type lithium ion conductor Li ₁₄ ZnGe ₄ O ₁₆ ; garnet type lithium ion conductor Li ₅ La ₃ M ₂ O ₁₂ , wherein M=Ta, Nb, Li ₇ La ₃ Zr ₂ O ₁₂ ; glass ceramic electrolyte Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₇ P ₃ S ₁₁ , Li ₁₀ GeP ₂ S ₁₂ .
3. The composite positive electrode material according to claim 1, wherein the positive electrode active material is selected from the group consisting of lithium cobaltate, lithium manganate, nickel manganese material, lithium iron phosphate, nickel cobalt manganese, nickel cobalt aluminum ternary material, and Sulfur-containing materials.
4. The composite positive electrode material according to claim 1, wherein the organic compound additive is selected from the group consisting of metal organic framework materials, oxygen-containing conjugated organic materials, conductive polymers, and organic sulfides.
5. A method for preparing a composite positive electrode material for a solid-state lithium ion battery, characterized in that it comprises the following steps:

   i) uniformly mixing a solid electrolyte or a precursor thereof with a positive electrode active material or a precursor thereof to obtain a mixture powder;

   Ii) The mixture powder is sintered at a high temperature to obtain a composite positive electrode material comprising a solid electrolyte and a positive electrode active material in the form of a powder.
6. The preparation method according to claim 5, further comprising the steps of:

   Iii) uniformly mixing the composite powder containing the solid electrolyte and the positive electrode active material with the organic compound additive to obtain a composite positive electrode material, wherein the weight ratio of the positive electrode active material, the solid electrolyte and the organic compound additive is 80 to 88:5 to 15:2. 8.
7. The production method according to claim 5, wherein in the composite positive electrode material, the solid electrolyte is contained in an amount of from 5% by weight to 40% by weight based on the total mass of the composite positive electrode material.
8. The preparation method according to claim 5, wherein the solid electrolyte is selected from the group consisting of NASICON type lithium ion conductors Li _1+x Ti _2-x M _x (PO ₄ ) ₃ , Li _1+x Ge _2-x M _x (PO ₄ ) ₃ , wherein 0.1<x<0.7, M=Al, Ga, In, Sc; perovskite-type lithium ion conductor Li _3x La _(2/3)-x TiO ₃ , where 0<x<0.16 LISICON type lithium ion conductor Li ₁₄ ZnGe ₄ O ₁₆ ; garnet type lithium ion conductor Li ₅ La ₃ M ₂ O ₁₂ , where M = Ta, Nb, Li ₇ La ₃ Zr ₂ O ₁₂ ; glass ceramic electrolyte Li ₂ S -SiS ₂ - Li ₃ PO ₄ , Li ₇ P ₃ S ₁₁ , Li ₁₀ GeP ₂ S ₁₂ .
9. The preparation method according to claim 5, wherein the positive active material is selected from the group consisting of lithium cobaltate, lithium manganate, nickel manganese material, lithium iron phosphate, nickel cobalt manganese, nickel cobalt aluminum ternary material, and Sulfur material.
10. The production method according to claim 5, wherein the sintering is carried out at 300 ° C - 1200 ° C for 8 to 24 hours.
11. A method for preparing a positive electrode of a solid-state lithium ion battery, characterized in that it comprises the following steps:

    i) using the preparation method according to claim 6 or 7 to prepare a composite positive electrode material;

    Ii) The obtained composite positive electrode material is formulated into a positive electrode slurry, and the obtained positive electrode slurry is applied onto a positive electrode substrate, dried, compacted, and slit to obtain a positive electrode.
12. A solid lithium ion battery positive electrode obtained by the production method according to claim 11.
13. A method for preparing a solid state lithium ion battery, comprising the steps of:

    i) using the preparation method of claim 12 to prepare a positive electrode;

    Ii) preparing the negative electrode material into a negative electrode slurry, applying the obtained negative electrode slurry onto the negative electrode substrate, drying, rolling, and slitting to obtain a negative electrode;

    Iii) The positive electrode and the negative electrode are laminated and assembled with a solid electrolyte to obtain a solid state lithium ion battery.
14. A solid state lithium ion battery obtained by the production method of claim 13.

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