Method for integrally printing solid-state battery

Abstract

The invention provides a method for integrally printing a solid-state battery, which comprises the following steps of: preparing an electrolyte-shell 3D cavity structure by adopting a fusion forming printing technology, injecting positive and negative electrode slurry into the 3D cavity structure, and fixedly forming a positive electrode and a negative electrode to form a three-dimensional positive electrode and a three-dimensional negative electrode. The solid-state battery is integrally formed, does not need to be assembled, has a three-dimensional electrode structure and is high in appearance customization degree. As the shell and the electrolyte occupy small volumes in the solid-state battery, the printing volume is greatly reduced, and the printing efficiency of the solid-state battery is improved.

Description

Technical Field

[0001] The present invention belongs to the field of batteries, and in particular relates to a method for integrally printing solid-state batteries. Background Art

[0002] Solid-state batteries use solid electrodes and solid electrolytes, and have low power density and high energy density. Due to the high power-to-weight ratio of solid-state batteries, they are ideal batteries for large equipment and facilities such as electric vehicles. Solid-state batteries use solid electrolytes or gel electrolytes to replace traditional liquid electrolytes and separators, which can inhibit lithium dendrites and improve battery safety performance. At the same time, lithium metal can be used for the negative electrode, which greatly improves the energy density. However, the poor contact between the solid electrolyte and the positive and negative electrodes leads to large interface impedance, which seriously affects the performance of the battery.

[0003] 3D printing technology, also known as additive manufacturing (AM), is a completely bottom-up manufacturing technology. It slices three-dimensional structures through computer software, breaks through the limitations of two-dimensional structures, and prints complex three-dimensional structures layer by layer into a solid. It has the advantages of low material loss, low cost and high speed.

[0004] Applying 3D printing technology to battery manufacturing, by constructing complex three-dimensional structures of electrodes and electrolytes, shortens the ion transmission distance, increases the electrochemical active area, and reduces the interface impedance. Existing 3D printing battery technology mainly uses direct ink writing (DIW) and photocuring (SLA) processes. Patent CN 114069024 A discloses a direct ink writing (DIW) process, which prints solid electrolytes on the diaphragm, prepares positive electrodes with traditional coating processes, and assembles them into solid-state batteries. Patent CN 114103115A uses photocuring (SLA) technology to print electrodes and assemble them into batteries.

[0005] However, there are at least the following problems when printing using the above two processes:

[0006] (1) Both processes require ink curing. During the ink curing process, the size changes greatly, which makes it difficult to match the printing ink, photopolymerizer, and active material, affecting the precision of the battery structure.

[0007] (2) The printing ink is mainly composed of positive / negative electrode active materials and printing ink / photocuring agent, and the printing ink / photocuring agent is an electrochemically inert compound. The electrochemically inert printing ink / photocuring agent leads to a decrease in the energy density of the positive / negative electrode active materials.

[0008] (3) The post-processing of both processes is cumbersome, time-consuming and inefficient.

[0009] Due to the flow rate limitation of the print head, the efficiency of melt forming printing technology is low. Taking the printing of 1.75mm diameter polylactic acid (PLA) filament as an example, the PLA flow rate is usually 20cc / h, and it takes 12.7h to print a pack of 269mm*95mm*10mm German Automotive Industry Association (VDA) size bare cells.

[0010] Although 3D printing eliminates the traditional battery manufacturing and assembly process, due to the above-mentioned technical limitations, 3D printing technology is currently difficult to apply in large-scale solid-state battery production.

[0011] Therefore, it is necessary to develop a method for printing solid-state batteries in one piece to improve the production efficiency of solid-state batteries. Summary of the invention

[0012] In order to solve the above problems, the present invention provides a method for printing solid-state batteries in one piece, which adopts melt molding printing technology to form an electrolyte-shell 3D chamber structure, and injects positive and negative electrode slurries into the 3D chamber structure to fix the positive and negative electrodes and form three-dimensional positive and negative electrodes. The solid-state battery is integrally formed, does not require assembly, has a three-dimensional electrode structure, and has a high degree of customization of the appearance. Since the volume of the shell and electrolyte accounts for a relatively small proportion in the solid-state battery, the printing volume is greatly reduced, and the printing efficiency of the solid battery is improved.

[0013] A method for integrally printing a solid-state battery comprises the following steps:

[0014] Step S1: heating electrolyte raw materials, stirring and blending to form a solid electrolyte printing precursor by extrusion; adding shell raw materials, stirring and blending to form a solid shell printing precursor by extrusion;

[0015] Step S2: preparing positive electrode slurry;

[0016] Step S3: preparing negative electrode slurry;

[0017] Step S4: designing an electrolyte-shell integrated 3D chamber structure by computer software, the 3D chamber structure comprising a shell 1 and an electrolyte 2; the shell 1 is located at the periphery of the structure and surrounds and forms an inner chamber; the electrolyte 2 is located in the inner chamber and connected to the shell 1, dividing the inner chamber into a plurality of slots; the slots comprise a positive electrode slot 4 and a negative electrode slot 3; using 3D printing slicing software to slice the 3D chamber structure to form a slice file;

[0018] Step S5: using melt forming printing technology to print the electrolyte-shell integrated 3D chamber structure into an electrolyte-shell integrated 3D chamber structure mold; the solid electrolyte printed by the melt forming printing technology has self-supporting ability;

[0019] Step S6: inserting a current collector into the slot; injecting positive electrode slurry and negative electrode slurry into positive electrode slot 4 and negative electrode slot 3 respectively; the positive electrode slurry and negative electrode slurry are fixed and formed under the regulation of the 3D cavity structure mold to form a three-dimensional structure, and a three-dimensional solid-state battery initial product is manufactured;

[0020] Step S7: drying the battery, removing the outer shell 1, and making a bare solid-state battery cell;

[0021] Step S8: Encapsulate the bare solid-state battery cells to make a solid-state battery.

[0022] The solid electrolyte printed by fusion molding printing technology has self-supporting capabilities.

[0023] Preferably, the electrolyte raw material is a mixture of a thermoplastic polymer electrolyte matrix and an inorganic filler.

[0024] Preferably, the thermoplastic polymer electrolyte matrix is ​​one or more of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride, polymethyl methacrylate, polyether, acrylonitrile butadiene styrene copolymer (ABS), polyethylene terephthalate glycol-1,4-cyclohexanedimethanol (PETG), and polylactic acid (PLA).

[0025] Preferably, the inorganic filler is one or more of aluminum oxide, zirconium oxide, silicon oxide, titanium oxide or barium titanate.

[0026] Preferably, the negative electrode slurry is hard carbon.

[0027] Preferably, the shell material is one or more of acrylonitrile butadiene styrene copolymer (ABS), polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), polylactic acid (PLA) or polyamide (PA).

[0028] Preferably, the shell material and the solid electrolyte matrix are different thermoplastic polymers, for example, the thermal expansion coefficients are different from those of the positive and negative electrodes, so as to facilitate the subsequent removal of the shell.

[0029] Preferably, the shell raw material is a thermally decomposable material, which facilitates the subsequent removal of the shell.

[0030] Preferably, the shell material is a photodegradable material, which facilitates the subsequent removal of the shell.

[0031] In the example, polyethylene terephthalate-1,4-cyclohexane dimethanol (PETG) can be used, which is a commercial printing material with a wall thickness of 0.4 to 2 mm.

[0032] Preferably, the computer software is solidworks or UG.

[0033] Preferably, the slice file is a G-CODE file for controlling the movement of the nozzle of the 3D printer.

[0034] Preferably, the printing method in step S5 is to switch printing through dual print heads.

[0035] Preferably, the printing method in step S5 is switching consumables printing.

[0036] Preferably, the gap between adjacent electrolytes is 1 micron to 999 microns.

[0037] Preferably, the gap between adjacent electrolytes is 1 mm to 10 mm.

[0038] The number of electrolyte layers is set according to needs, and the shape of the electrolyte is determined according to needs.

[0039] Preferably, the depth of the negative electrode slot is greater than that of the positive electrode slot, and the overhang structure is used to improve battery safety.

[0040] Preferably, the positive electrode slurry in step S2 further includes vacuum degassing treatment.

[0041] Preferably, the negative electrode slurry in step S3 further includes vacuum defoaming treatment.

[0042] Preferably, the injection method in step S6 is injection through a slurry injection mechanism 5 , and the slurry injection mechanism 5 includes a negative electrode nozzle 6 and a positive electrode nozzle 7 .

[0043] Preferably, the drying method in step S7 is vacuum oven drying at a drying temperature of 80-180°C.

[0044] Preferably, the packaging method in step S8 is hot pressing, with a pressure of 5Psi to 20Psi, a temperature of 50°C to 200°C, and a time of 1 to 30min.

[0045] Through the above technical solutions, the present invention produces the following technical effects:

[0046] (1) The melt forming printing technology is used to print the electrolyte-shell 3D chamber structure in one piece. The positive electrode slurry and the negative electrode slurry are fixed and formed under the regulation of the 3D chamber structure mold to form a three-dimensional structure. Since the volume of the shell and electrolyte accounts for a small proportion of the solid-state battery, the printing volume is greatly reduced, and the printing efficiency of the solid-state battery is improved.

[0047] (2) Due to the use of melt molding printing technology, the use of electrochemically inert printing inks or photocuring agents to prepare positive and negative electrodes can be avoided, which can significantly improve the energy density.

[0048] (3) The electrolyte-shell 3D chamber structure utilizes the self-supporting characteristics of the electrolyte-shell to form complex positive and negative electrode slots for accommodating positive and negative electrode slurries, increasing the contact area between the electrolyte and the positive and negative electrodes, shortening the ion transmission distance, and reducing the interface impedance.

[0049] (4) Solid-state batteries are integrally formed, require no assembly, have a complex three-dimensional electrode structure, and are highly customizable in appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the electrolyte-shell integrated 3D chamber structure.

[0051] Figure 2 It is an all-in-one printed solid-state battery flow chart.

[0052] In the figure, 1 is the shell; 2 is the electrolyte; 3 is the negative electrode slot; 4 is the positive electrode slot; 5 is the slurry injection mechanism; 6 is the negative electrode nozzle; and 7 is the positive electrode nozzle. DETAILED DESCRIPTION

[0053] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, embodiments are described below.

[0054] In the present application, the structures and proportions of the solid electrolyte and the shell in the accompanying drawings are only for reference and demonstration in understanding the technical solution and should not be construed as limiting the technical solution of the present invention.

[0055] Embodiment 1:

[0056] The integrated printing of solid-state batteries includes the following steps:

[0057] Step S1: Prepare a solid electrolyte printing precursor, mix acrylonitrile butadiene styrene copolymer (ABS) particles, lithium trifluoromethanesulfonyl imide (LiTFSI), polyethylene oxide (PEO) particles, and silicon dioxide powder in a mass ratio of 49:25:25:1, heat to 200°C, melt blend, and extrude into a linear printing precursor with a diameter of 1.75 mm. Add shell raw material polyethylene terephthalate-1,4-cyclohexane dimethanol (PETG), stir and blend, and extrude to form a solid shell printing precursor with a shell wall thickness of 0.4 to 2 mm.

[0058] Step S2: Prepare positive electrode slurry. At 20°C, add polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) to make the solid content reach 5% by mass fraction, stir for 4 hours, add conductive carbon black and lithium iron phosphate to make the mass ratio of lithium iron phosphate: polyvinylidene fluoride (PVDF): conductive carbon black to be 96:2:2. After continuing to stir for 4 hours, the positive electrode slurry is prepared and stored in a vacuum degassing manner.

[0059] Step S3: Prepare negative electrode slurry. At 20°C, add sodium carboxymethyl cellulose (CMC) to water to make the solid content reach 1.5% by mass fraction, stir for 4 hours, add conductive carbon black and graphite to make the mass ratio of graphite: CMC: conductive carbon black to be 95:3:2, continue stirring for 4 hours, complete the preparation of negative electrode slurry, and store it in a vacuum degassing manner.

[0060] Step S4: Designing an electrolyte-shell integrated 3D chamber structure through computer software, the 3D chamber structure includes a shell 1 and an electrolyte 2; the shell 1 is located on the periphery of the structure and surrounds an inner chamber; the electrolyte 2 is located in the inner chamber and connected to the shell 1, dividing the inner chamber into a plurality of slots; the slots include a positive electrode slot 4 and a negative electrode slot 3; using 3D printing slicing software to slice the 3D chamber structure to form a slicing file.

[0061] Step S5: Using the melt forming printing technology, a print head is used to print an electrolyte-shell integrated 3D chamber structure mold.

[0062] Step S6: inserting the current collector into the slot; injecting the positive electrode slurry and the negative electrode slurry into the positive electrode slot 4 and the negative electrode slot 3 respectively through the positive electrode nozzle and the negative electrode nozzle; using a 3D chamber structure mold to regulate the positive electrode slurry and the negative electrode slurry to be fixed and formed to form a three-dimensional structure; and manufacturing a solid-state battery initial product.

[0063] Step S7: Transfer the battery to a vacuum oven and vacuum dry it at 90°C for 30 minutes. After the battery cools to room temperature, remove the outer shell 1 to prepare a bare solid-state battery cell.

[0064] Step S8: hot-pressing and packaging the bare solid-state battery cells to produce a solid-state battery.

[0065] Embodiment 2:

[0066] Step S1: Prepare a solid electrolyte printing precursor, mix acrylonitrile butadiene styrene copolymer (ABS) particles, lithium trifluoromethanesulfonyl imide (LiTFSI), polyethylene oxide (PEO) particles, and silicon dioxide powder in a mass ratio of 49:25:25:1, heat to 200°C, melt blend, and extrude into a linear printing precursor with a diameter of 1.75 mm. Add shell raw material polyethylene terephthalate-1,4-cyclohexane dimethanol (PETG), stir and blend, and extrude to form a solid shell printing precursor with a shell wall thickness of 0.4 to 2 mm.

[0067] Step S2: prepare positive electrode slurry. At 20°C, add polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) to make the solid content reach 5% by mass fraction, stir for 4 hours, add conductive carbon black and lithium iron phosphate to make the mass ratio of lithium iron phosphate: polyvinylidene fluoride (PVDF): conductive carbon black to be 96:2:2. After continuing to stir for 4 hours, the positive electrode slurry is prepared and stored in a vacuum degassing manner.

[0068] Step S3: Prepare negative electrode slurry. At 20°C, add sodium carboxymethyl cellulose (CMC) to water to make the solid content reach 1.5% by mass fraction, stir for 4 hours, add conductive carbon black and graphite to make the mass ratio of graphite: CMC: conductive carbon black to be 95:3:2, continue stirring for 4 hours, complete the preparation of negative electrode slurry, and store it in a vacuum degassing manner.

[0069] Step S4: Designing an electrolyte-shell integrated 3D chamber structure through computer software, the 3D chamber structure includes a shell and an electrolyte; the shell is located on the periphery of the structure and surrounds an inner chamber; the electrolyte is two layers, located in the inner chamber, and connected to the shell, dividing the inner chamber into three slots, including a positive electrode slot and a negative electrode slot; using 3D printing slicing software to slice the 3D chamber structure to form a slicing file.

[0070] Step S5: Using the melt forming printing technology, by switching consumables, a 3D chamber structure mold of the electrolyte-shell integration is printed.

[0071] Step S6: insert a stainless steel bipolar current collector into the middle slot to divide the middle slot into a positive slot and a negative slot; inject the positive electrode slurry and the negative electrode slurry into the positive slot and the negative slot respectively through a nozzle; use a 3D chamber structure mold to regulate the positive electrode slurry and the negative electrode slurry to be fixed and formed to form a three-dimensional structure.

[0072] Step S7: transferring the battery to a vacuum oven and vacuum drying at 90° C. for 30 minutes, and removing the outer shell after the battery cools to room temperature to prepare a bare solid-state battery cell;

[0073] Step S8: hot-pressing and packaging the bare solid-state battery cells to produce a solid-state battery.

[0074] Comparative Example 1:

[0075] According to the prior art, direct writing ink technology is used to simultaneously print the solid electrolyte, the positive electrode, and the negative electrode. The other steps are the same as those in Example 1.

[0076] The cycle battery test and battery capacity test were performed using a blue battery tester. The comparison results of Example 1 and Comparative Example 1 show that the technical solution of the present invention significantly reduces the printing time of solid-state batteries by reducing the printing volume; due to the use of melt molding printing technology, the use of electrochemically inert printing inks or photocuring agents to prepare positive and negative electrodes can be avoided, which can significantly improve the energy density.

[0077] It can be seen from Example 2 that this patent easily realizes the preparation of bipolar solid-state batteries.

[0078] Table 1 Comparison of results of embodiments and comparative examples

[0079]

[0080] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for integrally printing a solid-state battery, comprising the following steps: Step S1: heating electrolyte raw materials, stirring and blending to form a solid electrolyte printing precursor by extrusion; heating shell raw materials, stirring and blending to form a solid shell printing precursor by extrusion; Step S2: preparing positive electrode slurry; Step S3: preparing negative electrode slurry; Step S4: designing an electrolyte-shell integrated 3D chamber structure by computer software, wherein the 3D chamber structure comprises a shell (1) and an electrolyte (2); the shell (1) is located at the periphery of the structure and encloses and forms an inner chamber; the electrolyte (2) is located in the inner chamber and connected to the shell (1), dividing the inner chamber into a plurality of slots; the slots comprise a positive electrode slot (4) and a negative electrode slot (3); and slicing the 3D chamber structure using 3D printing slicing software to form a slicing file; Step S5: using melt forming printing technology to print the electrolyte-shell integrated 3D chamber structure into an electrolyte-shell integrated 3D chamber structure mold; Step S6: inserting a current collector into the slot; injecting positive electrode slurry and negative electrode slurry into the positive electrode slot (4) and negative electrode slot (3) respectively; the positive electrode slurry and negative electrode slurry are fixed and formed under the regulation of the 3D cavity structure mold to form a three-dimensional structure, thereby manufacturing a three-dimensional solid-state battery initial product; Step S7: drying the solid-state battery product, removing the outer shell (1), and manufacturing a solid-state battery bare cell; Step S8: Encapsulate the bare solid-state battery cells to make a solid-state battery.

2. The method for integrally printing a solid-state battery according to claim 1, characterized in that: The electrolyte raw material is a mixture of a thermoplastic polymer electrolyte matrix and an inorganic filler.

3. The method for integrally printing a solid-state battery according to claim 2, characterized in that: The thermoplastic polymer electrolyte matrix is ​​one or more of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride, polymethyl methacrylate, polyether, acrylonitrile butadiene styrene copolymer (ABS), polyethylene terephthalate glycol-1,4-cyclohexanedimethanol (PETG), and polylactic acid (PLA).

4. The method for integrally printing a solid-state battery according to claim 2, characterized in that: The inorganic filler is one or more of aluminum oxide, zirconium oxide, silicon oxide, titanium oxide or barium titanate.

5. The method for integrally printing a solid-state battery according to claim 1, characterized in that: The shell material is one or more of acrylonitrile butadiene styrene copolymer (ABS), polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), polylactic acid (PLA) or polyamide (PA).

6. The method for integrally printing a solid-state battery according to claim 2, characterized in that: The number of layers of the electrolyte (2) is 2, and a stainless steel bipolar current collector is inserted into the middle slot, dividing the middle slot into a positive electrode slot and a negative electrode slot.

7. The method for integrally printing a solid-state battery according to claim 6, characterized in that: The depth of the negative electrode slot is greater than that of the positive electrode slot.

8. The method for integrally printing a solid-state battery according to claim 7, characterized in that: The positive electrode slurry in step S2 also includes vacuum degassing treatment; the drying method in step S7 is vacuum oven drying, and the drying temperature is 80-180°C; the packaging method in step S8 is hot pressing, the pressure is 5Psi-20Psi, the temperature is 50°C-200°C, and the time is 1-30min.

9. An integrated printed solid-state battery, characterized in that: Made by the method according to claim 9.

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