CN114142098A

CN114142098A - Preparation method and application of 3D printing solid-state battery

Info

Publication number: CN114142098A
Application number: CN202111404279.6A
Authority: CN
Inventors: 陈规伟; 董洁; 冀亚娟
Original assignee: Eve Energy Co Ltd
Current assignee: Eve Energy Co Ltd
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-03-04

Abstract

The invention provides a preparation method and application of a 3D printing solid-state battery. The preparation method comprises the following steps: preparing 3D printing ink; respectively and independently printing the 3D printing ink on the surfaces of the positive pole piece and the negative pole piece to obtain a solid electrolyte layer, and carrying out first solidification on the solid electrolyte layer to a viscous state to obtain a viscous state positive pole piece and a viscous state negative pole piece; and assembling the viscous positive pole piece and the viscous negative pole piece into a battery cell, performing second solidification on the battery cell, and assembling to obtain the 3D printing solid-state battery. The 3D printing solid electrolyte prepared by the invention can realize the close fit of the electrolyte and the electrode, improve the physical and chemical contact, improve the performance of the battery, effectively relieve the interface degradation caused by the volume change stress, has high precision, controllable structure and no waste material, is beneficial to environmental protection, and has high compatibility with the traditional preparation method, and the production cost can be reduced.

Description

Preparation method and application of 3D printing solid-state battery

Technical Field

The invention relates to the field of lithium ion batteries, relates to a solid electrolyte of a lithium ion battery, and particularly relates to a preparation method and application of a 3D printing solid battery.

Background

With the rapid development of the electric automobile industry, people increasingly demand high-energy-density and high-safety batteries. It is difficult for the currently commercialized battery to satisfy both requirements, and since the solid electrolyte in the solid-state battery is not combustible, the characteristics of the lithium metal negative electrode can be used, making it considered to be an important direction of the next-generation battery technology.

In the currently developed solid-state battery system, the solid-state battery cannot be commercialized and applied in a large scale due to a series of problems of a solid-state electrolyte/electrode interface, such as poor interface contact, poor electrochemical/chemical stability, large volume change stress and the like.

CN111509186B discloses various lithium ion solid-state battery anodes, their preparation process and lithium ion solid-state batteries. The polymer electrolyte is directly coated on the surface of the pole piece to form a solid electrolyte membrane, the solid electrolyte glue solution can penetrate into the positive pole piece and the negative pole piece in the coating process to provide ion conduction capability, and the dried electrolyte and the electrode can be tightly attached, so that interface gaps are avoided. And the polymer electrolyte has good flexibility and can bear the volume change stress generated in the charge and discharge processes of the active material. However, the method is limited by the current coating technology, when the coating is too thin, the stability of the coating is affected, meanwhile, in the coating process, too high solid content is not beneficial to reducing the thickness of the coating, and too low solid content is not beneficial to the stability of the coating, so that the uniformity of the coating is ensured. This method is therefore technically difficult to implement.

CN108321432A discloses a carbon-nitrogen polymer based solid electrolyte for inhibiting the growth of lithium dendrites, a preparation method and an application thereof, wherein a quasi-solid electrolyte capable of effectively inhibiting the growth of lithium dendrites in a lithium metal battery is prepared by taking a light carbon-nitrogen polymer as an electrolyte filler. The light carbon nitrogen polymer has a surprising layered structure, is beneficial to the absorption of electrolyte, thereby forming a muddy quasi-solid electrolyte which can be used for inhibiting the growth of dendritic crystals of a lithium cathode in a lithium metal battery. However, insufficient electrolyte addition leads to battery cycle afterflush, while excessive electrolyte addition reduces battery safety. And the solid electrolyte is difficult to be compatible with the electrolyte, and certain chemical reaction can occur when the solid electrolyte is contacted with the electrolyte, so that the scheme of adding the electrolyte can be only used as a transition scheme and can be replaced in long-term use.

CN112864454A discloses a multilayer solid electrolyte, a preparation method thereof, and a solid lithium battery. The solid electrolyte membranes of each layer are compacted by pressurization and then are compounded, so that the compaction degree of the solid electrolyte of each layer is improved, the solid electrolyte of the ductile layer is prevented from being deformed by extension due to different pressures required in the process of compacting by pressurization of the solid electrolyte of each layer, and the solid electrolyte membranes can be conveniently adapted to different electrolyte systems. By applying a large external pressure, the electrode/solid electrolyte is tightly attached under the action of external pressure, and the interface is kept stable in the working process. The method can ensure the high performance of the battery in a short time. However, as the working time of the battery increases, the positive and negative electrode active materials are broken under the action of huge external pressure due to certain volume expansion of the positive and negative electrode active materials, the structure is damaged, various electrical properties are greatly degraded, and the long-term stable circulation of the battery is not facilitated. In addition, the thickness of the solid electrolyte membrane is generally less than 20 μm, and the electrolyte membrane is easily damaged under the action of external pressure and internal volume stress, so that the cell is short-circuited and cannot work normally.

How to realize the close fit of the electrolyte and the electrode, improve the physical and chemical contact and improve the battery performance is an important research direction in the field.

Disclosure of Invention

The invention aims to provide a gel electrolyte sprayed and printed on the surface of an electrode by a 3D printing technology, which can effectively relieve interface degradation caused by volume change stress.

In order to achieve the purpose, the invention adopts the following technical scheme:

one of the purposes of the invention is to provide a preparation method of a 3D printing solid-state battery, which comprises the following steps:

preparing 3D printing ink;

respectively and independently printing the 3D printing ink on the surfaces of the positive pole piece and the negative pole piece to obtain a solid electrolyte layer, and carrying out first solidification on the solid electrolyte layer to a viscous state to obtain a viscous state positive pole piece and a viscous state negative pole piece;

and assembling the viscous positive pole piece and the viscous negative pole piece into a battery cell, performing second solidification on the battery cell, and assembling to obtain the 3D printing solid-state battery.

The method comprises the step of spraying and printing a layer of gel electrolyte on the surface of an electrode by a 3D printing technology. The process is similar to pole piece coating electrolyte membrane in the thought, but has higher feasibility. 3D prints precision itself extremely high, can accomplish the printing thickness of about 20 mu m, and prints the structure controllable, can design electrolyte inner structure according to actual demand. The gel electrolyte itself has very high ionic conductivity (10)^-3S cm^-1) And the flexibility is superior to that of oxide electrolyte and sulfide electrolyte, and the interface degradation caused by the volume change stress can be effectively relieved. 3D prints gel electrolyte and only needs to introduce two kinds of equipments of 3D printing shower nozzle and ultraviolet emitter, and it is highly similar to traditional electric core manufacturing, can reduce equipment cost.

The anode plate comprises, by mass, 85-95% of an anode active material, 0.5-5% of an electronic conductive agent, 0.5-5% of an ionic conductive agent and 1.5-5% of a binder.

Wherein the mass fraction of the positive electrode active material may be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95%, etc., the mass fraction of the electron conductive agent may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., the mass fraction of the ion conductive agent may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., the mass fraction of the binder may be 1.5%, 2%, 5.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., but is not limited to the recited values, and other values not recited in the above numerical ranges are also applicable.

Preferably, the solid content of the raw material of the positive electrode sheet in the positive electrode solvent is 30-80%, wherein the solid content may be 30%, 40%, 50%, 60%, 70%, or 80%, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

Preferably, the cathode solvent includes any one of N-methylpyrrolidone, N-dimethylformamide, dimethylacetamide, or a combination of at least two thereof, wherein the combination is typically but not limited to: a combination of N-methylpyrrolidone and N, N-dimethylformamide, a combination of N, N-dimethylformamide and dimethylacetamide, a combination of N-methylpyrrolidone and dimethylacetamide, or the like.

Preferably, the positive electrode active material includes any one of NCM ternary material, NCA ternary material, lithium iron phosphate, lithium manganate, lithium cobaltate, sulfur carbon composite material and sulfur carbon composite material derivative or a combination of at least two thereof, wherein typical but non-limiting examples of the combination are a combination of NCM ternary material and NCA ternary material, a combination of NCA ternary material and lithium iron phosphate, a combination of lithium iron phosphate and lithium manganate, a combination of lithium manganate and lithium cobaltate, a combination of lithium cobaltate and sulfur carbon composite material or a combination of lithium cobaltate and sulfur carbon composite material derivative, and the like.

Preferably, the electron conductive agent comprises any one of conductive carbon black, conductive graphite, carbon fiber or carbon nanotube or a combination of at least two thereof, wherein typical but non-limiting examples of the combination are a combination of conductive carbon black and conductive graphite, a combination of conductive graphite and carbon fiber, a combination of carbon fiber and carbon nanotube or a combination of conductive graphite and carbon nanotube, and the like.

Preferably, the ionic conductive agent includes any one of lithium lanthanum zirconium oxygen, lithium titanium aluminum phosphate or lithium lanthanum titanium oxygen or a combination of at least two thereof, wherein typical but non-limiting examples thereof are a combination of lithium lanthanum zirconium oxygen and lithium titanium aluminum phosphate, a combination of lithium titanium aluminum phosphate and lithium lanthanum titanium oxygen, a combination of lithium lanthanum zirconium oxygen and lithium lanthanum titanium oxygen, or the like.

Preferably, the binder comprises polyvinylidene fluoride and/or polyimide.

The cathode plate comprises, by mass, 90-98% of a cathode active material, 0.5-5% of an electronic conductive agent, 0.5-5% of an ionic conductive agent and 1.5-5% of a binder.

Wherein the mass fraction of the negative electrode active material may be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc., the mass fraction of the conductive agent may be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., and the mass fraction of the binder may be 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., but is not limited to the recited values, and other values not recited in the above-mentioned numerical ranges are also applicable.

Preferably, the solid content of the raw material of the negative electrode sheet in the negative electrode solvent is 30-80%, wherein the solid content may be 30%, 40%, 50%, 60%, 70%, or 80%, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

Preferably, the negative electrode solvent comprises deionized water.

Preferably, the negative active material includes any one or a combination of at least two of graphite, hard carbon, natural graphite, soft carbon, silica, silicon carbon, or tin carbon, wherein typical but non-limiting examples of the combination are a combination of graphite and hard carbon, a combination of hard carbon and natural graphite, a combination of natural graphite and soft carbon, a combination of soft carbon and silica, a combination of silica and silicon carbon, or a combination of silicon carbon and tin carbon, and the like.

Preferably, the binder includes any one of polyvinylidene fluoride, polyimide, polyvinyl alcohol, polyacrylic acid, styrene-butadiene rubber, or sodium carboxymethylcellulose, or a combination of at least two thereof, wherein typical but non-limiting examples thereof are a combination of polyvinylidene fluoride and polyimide, a combination of polyimide and polyvinyl alcohol, a combination of polyvinyl alcohol and polyacrylic acid, a combination of polyacrylic acid and styrene-butadiene rubber, or a combination of styrene-butadiene rubber and sodium carboxymethylcellulose, and the like.

According to the preferable technical scheme, the 3D printing ink comprises, by mass, 1-10% of an inorganic filler, 50-80% of an electrolyte, 1-40% of a polymer monomer, 0.5-1% of a thickener and 0.05-0.1% of an initiator.

Wherein the mass fraction of the inorganic filler may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc., the mass fraction of the electrolyte may be 50%, 55%, 60%, 65%, 70%, 75%, or 80%, etc., wherein the mass fraction of the polymer monomer may be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, etc., wherein the mass fraction of the thickener may be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%, etc., wherein the mass fraction of the initiator may be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%, etc.

As a preferred technical scheme of the invention, the inorganic filler comprises SiO₂、Al₂O₃Any one or a combination of at least two of montmorillonite, LLZO, LATP, LAGP or LLTO, wherein a typical but non-limiting example of such a combination is SiO₂And Al₂O₃Combination of (1) and Al₂O₃And a combination of montmorillonite, a combination of montmorillonite and LLZO, a combination of LLZO and LATPCombinations, combinations of LATP and LAGP, or combinations of LAGP and LLTO, and the like.

As a preferred embodiment of the present invention, the electrolyte includes any one or a combination of at least two of ethylene carbonate, propylene carbonate, dimethyl carbonate or ethyl methyl carbonate, and typical but non-limiting examples of the combination include a combination of ethylene carbonate and propylene carbonate, a combination of propylene carbonate and dimethyl carbonate, a combination of dimethyl carbonate and ethyl methyl carbonate, or a combination of propylene carbonate and ethyl methyl carbonate, and the like.

Preferably, the polymer monomer comprises any one of MMA, PETA, PETEA, EGPEA, EGDMA, acrylonitrile, ethylene carbonate, vinylene carbonate, ethylene oxide, or 1, 3-dioxolane, or a combination of at least two thereof, with typical but non-limiting examples being a combination of MMA and PETA, PETA and PETEA, PETEA and EGPEA, EGDMA and acrylonitrile, ethylene carbonate and vinylene carbonate, or ethylene oxide and 1, 3-dioxolane, and the like.

As a preferred technical scheme of the invention, the thickening agent comprises PMMA and/or polyethylene oxide.

Preferably, the initiator comprises any one or a combination of at least two of 1-hydroxycyclohexylphenylketone, 2-hydroxy-methylphenylpropane-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, tolidine ketone, 2-isopropylthioxanthone or 2, 4, 6- (trimethylbenzoyl) -diphenylphosphine oxide, wherein typical but non-limiting examples of the combination are the combination of 1-hydroxycyclohexylphenylketone and 2-hydroxy-methylphenylpropane-1-one, the combination of 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone and benzoin dimethyl ether, A combination of tolidine and 2-isopropylthioxanthone or a combination of 2, 4, 6- (trimethylbenzoyl) -diphenylphosphine oxide and 1-hydroxycyclohexylphenylmethanone, and the like.

In a preferred embodiment of the present invention, the thickness of the solid electrolyte layer on the surface of the positive electrode sheet is 5 to 20 μm, wherein the thickness may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.

Preferably, the thickness of the solid electrolyte layer on the surface of the negative electrode plate is 5 to 20 μm, wherein the thickness can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, but is not limited to the listed values, and other values not listed in the numerical value range are also applicable.

As a preferable technical solution of the present invention, the first curing is ultraviolet curing.

Preferably, the first curing ultraviolet light has a wavelength of 10 to 400nm, wherein the wavelength may be 10nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, etc., but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first curing time is 5-30 min, wherein the time can be 5min, 8min, 10min, 12min, 14min, 16min, 18min, 20min, 22min, 24min, 26min, 28min or 30min, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature of the first curing is 40 to 80 ℃, wherein the temperature may be 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

In a preferred embodiment of the present invention, the second curing is thermal curing.

Preferably, the second curing time is 3 to 6 hours, wherein the time can be 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours, etc., but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature of the second curing is 40 to 60 ℃, wherein the temperature may be 40 ℃, 42 ℃, 44 ℃, 46 ℃, 48 ℃, 50 ℃, 52 ℃, 54 ℃, 56 ℃, 58 ℃ or 60 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

As a preferred technical solution of the present invention, the preparation method comprises:

preparing 3D printing ink;

respectively and independently printing the 3D printing ink on the surfaces of the positive pole piece and the negative pole piece to obtain solid electrolyte layers with the thicknesses of 5-20 microns, and curing the surfaces of the solid electrolyte layers for 5-30 min by using ultraviolet light with the wavelength of 10-400 nm to be in a viscous state to obtain a viscous positive pole piece and a viscous negative pole piece;

and assembling the viscous positive pole piece and the viscous negative pole piece into a battery cell, carrying out thermocuring on the battery cell at 40-60 ℃ for 3-6 h, and then loading the battery cell into a battery shell to obtain the 3D printing solid-state battery.

The second purpose of the present invention is to provide an application of the preparation method of the 3D printing solid-state battery according to the first purpose, wherein the preparation method is applied to the field of lithium ion batteries.

Compared with the prior art, the invention has the following beneficial effects:

(1) the 3D printing solid electrolyte prepared by the invention can realize the close fit of the electrolyte and the electrode, improve the physical and chemical contact, improve the performance of the battery, effectively relieve the interface degradation caused by the volume change stress, and reduce the interface impedance to 760m omega.

(2) The 3D printing electrolyte has high precision and controllable structure, and the electrolyte structure can be designed according to actual requirements.

(3) In the invention, no waste material is generated in the 3D printing process, which is beneficial to environmental protection and can reduce the production cost.

Drawings

Fig. 1 is a discharge capacity diagram of a 3D printed battery in embodiment 1 of the present invention.

Fig. 2 is a flowchart of 3D printing of batteries in examples 1 to 9 of the present invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a 3D printing solid-state battery preparation method, which comprises the following steps:

(1) preparing a positive pole piece: and uniformly mixing and stirring 95 wt% of lithium iron phosphate, 1 wt% of conductive carbon black, 2 wt% of lithium lanthanum zirconium oxide, 2 wt% of polyvinylidene fluoride and NMP to obtain the anode slurry with the solid content of 50%. And then uniformly coating the slurry on the two sides of the aluminum foil, and drying, rolling, slitting and the like to obtain the required positive pole piece.

(2) Preparing a negative pole piece: mixing and stirring 95 wt% of graphite, 1 wt% of conductive carbon black, 2 wt% of lithium lanthanum zirconium oxide and 2 wt% of polyvinyl alcohol with solvent deionized water uniformly to obtain the cathode slurry with the solid content of 50%. And then uniformly coating the slurry on the two sides of the copper foil, and drying, rolling, slitting and the like to obtain the required negative pole piece.

(3) Preparation of 3D printing ink: weighing SiO according to mass ratio₂4.22 wt%, 65 wt% of ethylene carbonate and 20 wt% of MMA20 wt%, and adding the materials into a closed container, performing ultrasonic treatment for 35min, and stirring for 8h to obtain SiO₂Uniformly dispersed in the 3D printing ink. Then, PMMA0.7wt% was added to the above ink, and the viscosity of the ink was controlled to 13 mPas (55 ℃ C.) by changing the PMMA content. And finally, adding 0.08 wt% of 1-hydroxycyclohexyl phenyl ketone into the mixture, and continuously stirring for 6 hours to obtain the required 3D printing ink.

(4)3D printing solid electrolyte: and 3D printing ink is filled into a needle cylinder, a needle head with the inner diameter of 350 mu m is selected, and a solid electrolyte layer with the thickness of 13 mu m is printed on the surface of the cut positive pole piece by using a 3D printer. Similarly, a 13 μm solid electrolyte layer was printed on the surface of the negative electrode sheet. And the curing degree of the 3D printing ink is adjusted to be in an incompletely cured viscous state by controlling the irradiation time of the ultraviolet light at 280nm for 10 min.

(5) Assembling the battery cell: the positive pole piece and the negative pole piece prepared in the process are prepared into a laminated core, and then a layer of diaphragm is wrapped outside the laminated core to fix the positive pole piece and the negative pole piece, so that the movement of the laminated core is prevented from generating short circuit. And then, obtaining the battery cell through a tab welding machine, side sealing of the soft package battery, top sealing and pre-sealing.

(6) And (3) secondary curing of the battery cell: at this time, the solid electrolyte is not completely solidified, and flowable components still exist in the battery, which is not beneficial to improving the safety of the battery core. Therefore, the battery cell is kept still for 4.5 hours at the temperature of 50 ℃ for secondary curing. After the solidification is finished, the solid electrolyte layers on the surfaces of the anode and the cathode can be completely solidified to form a whole, the strength is greatly improved, and the internal micro short circuit of the battery cell in the use process is avoided.

The discharge capacity of the 3D printed battery in this embodiment is shown in fig. 1, and the flowchart of the 3D printed battery is shown in fig. 2.

Example 2

(1) preparing a positive pole piece: mixing 85 wt% of lithium manganate, 5 wt% of conductive graphite, 5 wt% of lithium aluminum titanium phosphate, 5 wt% of polyimide and NMP, and uniformly stirring to obtain the anode slurry with the solid content of 30%. And then uniformly coating the slurry on the two sides of the aluminum foil, and drying, rolling, slitting and the like to obtain the required positive pole piece.

(2) Preparing a negative pole piece: mixing and stirring 90 wt% of hard carbon, 5 wt% of conductive graphite, 2 wt% of lithium aluminum titanium phosphate and 3 wt% of polyvinyl alcohol with solvent deionized water uniformly to obtain negative electrode slurry with the solid content of 30%. And then uniformly coating the slurry on the two sides of the copper foil of the negative current collector, and drying, rolling, slitting and the like to obtain the required negative pole piece.

(3) Preparation of 3D printing ink: weighing Al according to mass ratio₂O₃8.9 wt%, 50 wt% of propylene carbonate and 40 wt% of PETA, adding the materials into a closed container, performing ultrasonic treatment for 10min, and stirring for 4h to enable Al to be contained₂O₃Uniformly dispersed in the 3D printing ink. And 1% by weight of polyoxyethylene was added to the above ink to control the viscosity of the ink to 5 mPas (55 ℃ C.) by changing the polyoxyethylene content. Finally, to itAdding 0.1 wt% of 2-hydroxy-methyl phenyl propane-1-ketone, and continuously stirring for 4h to obtain the required 3D printing ink.

(4)3D printing solid electrolyte: and (3) filling the 3D printing ink into a needle cylinder, selecting a needle head with the inner diameter of 200 mu m, and printing a solid electrolyte layer with the thickness of 5 mu m on the surface of the cut positive pole piece by using a 3D printer. Similarly, a 5 μm solid electrolyte layer was printed on the surface of the negative electrode plate. And the curing degree of the 3D printing ink is adjusted to be in an incompletely cured viscous state by controlling the irradiation of ultraviolet light at 200nm for 10 min.

(6) And (3) secondary curing of the battery cell: at this time, the solid electrolyte is not completely solidified, and flowable components still exist in the battery, which is not beneficial to improving the safety of the battery core. Therefore, the battery core is kept still for 6 hours at the temperature of 40 ℃ for secondary curing. After the solidification is completed, the solid electrolyte layers on the surfaces of the anode and the cathode can be completely solidified to form a whole, the strength is greatly improved, the internal micro short circuit of the battery cell in the use process is avoided, and the flow chart of the 3D printing battery is shown in fig. 2.

Example 3

(1) preparing a positive pole piece: 95 wt% of lithium cobaltate, 2 wt% of carbon fiber, 1 wt% of lithium lanthanum titanium oxide, 2 wt% of binder and NMP are mixed and stirred uniformly to obtain the anode slurry with the solid content of 80%. And then uniformly coating the slurry on the two sides of a positive current collector, and drying, rolling, slitting and the like to obtain the required positive pole piece.

(2) Preparing a negative pole piece: 97 wt% of natural graphite, 0.5 wt% of conductive graphite, 0.5 wt% of lithium aluminum titanium phosphate and 2 wt% of polyacrylic acid are mixed with deionized water and stirred uniformly to obtain negative electrode slurry with the solid content of 80%. And then uniformly coating the slurry on the two sides of a negative current collector, and drying, rolling, slitting and the like to obtain the required negative pole piece.

(3) Preparation of 3D printing ink: weighing 10 wt% of montmorillonite, 80 wt% of dimethyl carbonate and 8.85 wt% of acrylonitrile according to the mass ratio, adding the materials into a closed container, performing ultrasonic treatment for 60min, and stirring for 4h to uniformly disperse the montmorillonite in the 3D printing ink. To the above ink was added PMMA1 wt%, and the viscosity of the ink was controlled to 20 mPas (55 ℃ C.) by changing the PMMA content. And finally, adding 0.05 wt% of 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-acetone, and continuing stirring for 8 hours to obtain the required 3D printing ink.

(4)3D printing solid electrolyte: and (3) filling the 3D printing ink into a needle cylinder, selecting a needle head with the inner diameter of 500 mu m, and printing a solid electrolyte layer with the thickness of 20 mu m on the surface of the cut positive pole piece by using a 3D printer. Similarly, a20 μm solid electrolyte layer was printed on the surface of the negative electrode sheet. And the curing degree of the 3D printing ink is adjusted to be in an incompletely cured viscous state by controlling the ultraviolet light to irradiate for 15min at 300 nm.

(6) And (3) secondary curing of the battery cell: at this time, the solid electrolyte is not completely solidified, and flowable components still exist in the battery, which is not beneficial to improving the safety of the battery core. Therefore, the battery cell is stood for 3 hours at the temperature of 60 ℃ for secondary curing. After the solidification is finished, the solid electrolyte layers on the surfaces of the anode and the cathode can be completely solidified to form a whole, the strength is greatly improved, and the internal micro short circuit of the battery cell in the use process is avoided. The flow chart of the 3D printing battery of the embodiment is shown in FIG. 2.

Example 4

(1) preparing a positive pole piece: 87 wt% of NCM ternary material, 3 wt% of conductive graphite, 5 wt% of lithium aluminum titanium phosphate, 5 wt% of polyvinylidene fluoride and NMP are mixed and stirred uniformly to obtain the anode slurry with the solid content of 50%. And then uniformly coating the slurry on the two sides of the aluminum foil of the positive current collector, and drying, rolling, slitting and the like to obtain the required positive pole piece.

(2) Preparing a negative pole piece: mixing and stirring 92 wt% of silica, 4.5 wt% of carbon fiber, 2 wt% of lithium lanthanum zirconium oxide and 1.5 wt% of styrene butadiene rubber with solvent deionized water uniformly to obtain the negative electrode slurry with the solid content of 45%. And then uniformly coating the slurry on the two sides of the copper foil of the negative current collector, and drying, rolling, slitting and the like to obtain the required negative pole piece.

(3) Preparation of 3D printing ink: weighing 3 wt% of LATP, 80 wt% of ethyl methyl carbonate and 19.45 wt% of ethylene oxide according to the mass ratio, adding the materials into a closed container, carrying out ultrasonic treatment for 25min, and stirring for 6h to uniformly disperse the LATP in the 3D printing ink. And 0.5 wt% of polyoxyethylene was added to the above ink to control the viscosity of the ink to 8 mPas (55 ℃ C.) by changing the polyoxyethylene content. And finally, adding 0.05 wt% of 2, 4, 6- (trimethylbenzoyl) -diphenylphosphine oxide into the mixture, and continuously stirring for 5 hours to obtain the required 3D printing ink.

(4)3D printing solid electrolyte: and (3) filling the 3D printing ink into a needle cylinder, selecting a needle head with the inner diameter of 300 mu m, and printing a solid electrolyte layer with the thickness of 8 mu m on the surface of the cut positive pole piece by using a 3D printer. Similarly, a 8 μm solid electrolyte layer was printed on the surface of the negative electrode plate. And the curing degree of the 3D printing ink is adjusted to be in an incompletely cured viscous state by controlling the ultraviolet light to irradiate for 20min at 300 nm.

(6) And (3) secondary curing of the battery cell: at this time, the solid electrolyte is not completely solidified, and flowable components still exist in the battery, which is not beneficial to improving the safety of the battery core. Therefore, the battery core is kept still for 4 hours at the temperature of 45 ℃ for secondary curing. After the solidification is finished, the solid electrolyte layers on the surfaces of the anode and the cathode can be completely solidified to form a whole, the strength is greatly improved, and the internal micro short circuit of the battery cell in the use process is avoided. The flow chart of the 3D printing battery of the embodiment is shown in FIG. 2.

Example 5

(1) preparing a positive pole piece: 95 wt% of lithium cobaltate, 2 wt% of carbon fiber, 1 wt% of lithium lanthanum titanium oxide, 2 wt% of binder and NMP are mixed and stirred uniformly to obtain the anode slurry with the solid content of 80%. And then uniformly coating the slurry on the two sides of the aluminum foil of the positive current collector, and drying, rolling, slitting and the like to obtain the required positive pole piece.

(2) Preparing a negative pole piece: 97 wt% of tin carbon, 1 wt% of carbon nano tube, 0.5 wt% of lithium lanthanum zirconium oxide and 1.5 wt% of sodium carboxymethylcellulose are mixed with solvent deionized water and stirred uniformly to obtain negative electrode slurry with solid content of 70%. And then uniformly coating the slurry on the two sides of the copper foil of the negative current collector, and drying, rolling, slitting and the like to obtain the required negative pole piece.

(3) Preparation of 3D printing ink: weighing LLTO7 wt%, propylene carbonate 70 wt% and EGDMA22.45wt% according to the mass ratio, adding the materials into a closed container, performing ultrasonic treatment for 50min, and stirring for 10h to uniformly disperse the inorganic filler in the 3D printing ink. And 0.5 wt% of polyoxyethylene was added to the above ink to control the viscosity of the ink to 17 mPas (55 ℃ C.) by changing the polyoxyethylene content. And finally, adding 0.05 wt% of benzoin dimethyl ether into the ink, and continuing stirring for 7 hours to obtain the required 3D printing ink.

(4)3D printing solid electrolyte: and (3) filling the 3D printing ink into a needle cylinder, selecting a needle head with the inner diameter of 400 mu m, and printing a solid electrolyte layer with the thickness of 17 mu m on the surface of the cut positive pole piece by using a 3D printer. Similarly, a 17 μm solid electrolyte layer was printed on the surface of the negative electrode sheet. And the curing degree of the 3D printing ink is adjusted to be in an incompletely cured viscous state by controlling the ultraviolet light to be 400nm for 5 min.

(6) And (3) secondary curing of the battery cell: at this time, the solid electrolyte is not completely solidified, and flowable components still exist in the battery, which is not beneficial to improving the safety of the battery core. Therefore, the battery cell is kept still for 4 hours at the temperature of 55 ℃ for secondary curing. After the solidification is finished, the solid electrolyte layers on the surfaces of the anode and the cathode can be completely solidified to form a whole, the strength is greatly improved, and the internal micro short circuit of the battery cell in the use process is avoided. The flow chart of the 3D printing battery of the embodiment is shown in FIG. 2.

Example 6

In this example, the printing thickness of the positive electrode sheet and the negative electrode sheet in the step (4) was replaced with 3 μm, and the other conditions were the same as those in example 1.

Example 7

In this example, the printing thickness of each negative electrode piece of the positive electrode piece in the step (4) was replaced with 22 μm, and the other conditions were the same as in example 1.

Example 8

In this example, the temperature of the secondary curing in the step (6) was replaced with 48 ℃ and the other conditions were the same as in example 1.

Example 9

In this example, the temperature of the secondary curing in the step (6) was changed to 62 ℃ and the other conditions were the same as in example 1.

Comparative example 1

In the comparative example, the 3D printing ink obtained in the step (3) is uniformly coated on the surfaces of the positive pole piece and the negative pole piece instead of the step (4), ultraviolet light is used for irradiating the surfaces of the positive pole piece and the negative pole piece to be in an incomplete curing state, and other conditions are the same as those of the example 1.

Comparative example 2

In the comparative example, the steps (4) to (6) are removed, the step (4) is replaced by preparing the positive pole piece and the negative pole piece into the battery cell, 3D printing ink is directly injected into the battery cell, and the all-solid-state battery is obtained through ultraviolet light one-time curing, wherein other conditions are the same as those in the embodiment 1.

The ac impedance, first-turn coulombic efficiency, and capacity exertion rate tests were performed on examples 1 to 9 and comparative examples 1 to 2, and the test results are shown in table 1.

The alternating current impedance is tested by using a CHI660 electrochemical workstation instrument, the first-turn coulombic efficiency and the capacity are tested by using a 5V1A blue instrument, and the capacity exertion rate testing method is that the ratio of the actual capacity to the capacity is multiplied by 100%.

TABLE 1

	ACR/mΩ	First round of coulombic efficiency%	Capacity exertion rate/%)
				Example 1	854.2	86.2％	96.8％
Example 2	760.1	87.3％	99.7％
				Example 3	822.4	84.2％	98.3％
Example 4	896.7	81.3％	95.4％
				Example 5	956.4	82.6％	96.4％
Example 6	650.1	75.4％	90.1％
				Example 7	985.4	76.6％	88.7％
Example 8	820.6	73.8％	92.5％
				Example 9	869.3	78.9％	94.1％
Comparative example 1	1251.3	75.5％	89.1％
				Comparative example 2	1146.3	72.6％	92.1

Through comparison of examples 1-5, it can be seen that the cells developed based on PETA have the optimal electrochemical performance, show the lowest alternating current internal resistance, only 760.1m Ω, and the first effect reaches 86.2%, and can exert capacity close to the design capacity. It can be seen from comparing examples 1, 6 and 7 that when the coating thickness is too low, the cell is prone to micro-short circuits, resulting in a decrease in first-effect and playable capacity. As can be seen from comparing example 1, example 8 and example 9, the secondary curing temperature has a great influence on the battery performance, when the curing temperature is low, the material is not cured completely, and internal micro short circuits are likely to occur, and when the curing temperature is too high, the material curing speed is too fast, so that a uniform cured layer cannot be formed, and lithium ion transmission is not facilitated. As can be seen from the comparison of example 1 and comparative examples 1 to 2, the battery cell obtained by the 3D printing method has the lowest internal resistance, and the coulombic efficiency and the capacity exertion rate are both significantly improved, which indicates that the 3D printing method is more suitable for the in-situ curing system.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. A preparation method of a 3D printing solid-state battery is characterized by comprising the following steps:

preparing 3D printing ink;

2. The preparation method of claim 1, wherein the raw materials of the 3D printing ink comprise, by mass, 1-10% of an inorganic filler, 50-80% of an electrolyte, 1-40% of a polymer monomer, 0.5-1% of a thickener, and 0.05-0.1% of an initiator.

3. The method according to claim 2, wherein the inorganic filler comprises SiO₂、Al₂O₃Any one or a combination of at least two of montmorillonite, LLZO, LATP, LAGP or LLTO.

4. A production method according to claim 2 or 3, wherein the electrolytic solution includes a solvent, a lithium salt, and an additive;

preferably, the solvent comprises any one of ethylene carbonate, propylene carbonate, dimethyl carbonate or ethyl methyl carbonate or a combination of at least two of the above;

preferably, the lithium salt includes LiPF₆、LiTFSI、LiFSI、LiBF₄Either one or a combination of both;

preferably, the additive comprises any one of vinylene carbonate, fluoroethylene carbonate, cyclohexylbenzene, propylene sulfite or ethylene sulfate or a combination of at least two of the vinylene carbonate, the fluoroethylene carbonate, the cyclohexylbenzene, the propylene sulfite or the ethylene sulfate;

preferably, the polymer monomer comprises any one of MMA, PETA, PETEA, EGPEA, EGDMA, acrylonitrile, ethylene carbonate, vinylene carbonate, ethylene oxide or 1, 3-dioxolane or a combination of at least two thereof.

5. The production method according to any one of claims 2 to 4, wherein the thickener comprises PMMA and/or polyethylene oxide;

preferably, the initiator comprises any one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-methylphenyl propane-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, tolidine, 2-isopropyl thioxanthone or 2, 4, 6- (trimethylbenzoyl) -diphenyl phosphine oxide or a combination of at least two of the above.

6. The preparation method according to any one of claims 1 to 5, wherein the thickness of the solid electrolyte layer on the surface of the positive electrode plate is 5 to 20 μm;

preferably, the thickness of the solid electrolyte layer on the surface of the negative pole piece is 5-20 μm.

7. The production method according to any one of claims 1 to 6, wherein the first curing is ultraviolet curing;

preferably, the wavelength of the first curing ultraviolet light is 10-400 nm;

preferably, the first curing time is 5-30 min;

preferably, the temperature of the first curing is 45-80 ℃.

8. The method of any one of claims 1-7, wherein the second curing is thermal curing;

preferably, the second curing time is 3-6 h;

preferably, the temperature of the second curing is 40-60 ℃.

9. The production method according to any one of claims 1 to 8, characterized by comprising:

preparing 3D printing ink;

10. Use of a method of manufacturing a 3D printed solid-state battery according to any of claims 1 to 9, characterized in that the method of manufacturing is applied in the field of lithium ion batteries.