A method of integrally printing a solid-state battery

Abstract

The application provides a method for integrally printing a solid-state battery, adopts a melt forming printing technology, prepares an electrolyte-shell 3D chamber structure, injects positive and negative electrode slurries into the 3D chamber structure, fixes and forms the positive and negative electrodes, and forms three-dimensional structure positive and negative electrodes. The solid-state battery is integrally formed and does not need to be assembled, has a three-dimensional electrode structure, and has high customization degree of appearance. Since the volume of the shell and the electrolyte accounts for a small proportion 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] This invention belongs to the field of batteries, and specifically relates to a method for integrally printing solid-state batteries. Background Technology

[0002] Solid-state batteries use solid electrodes and solid electrolytes, exhibiting lower power density but higher energy density. Due to their high power-to-weight ratio, solid-state batteries are ideal for large-scale equipment and facilities such as electric vehicles. Solid-state batteries use solid electrolytes or gel electrolytes instead of traditional liquid electrolytes and separators, which can suppress lithium dendrite formation and improve battery safety. Furthermore, lithium metal can be used as the negative electrode, significantly increasing energy density. However, the poor contact between the solid electrolyte and the positive and negative electrodes results in high interfacial impedance, severely impacting battery performance.

[0003] 3D printing technology, or additive manufacturing (AM), is a completely bottom-up manufacturing technology that uses computer software to slice three-dimensional structures, breaking through the limitations of two-dimensional structures, and stacking complex three-dimensional structures layer by layer to print them into solid objects. It has the advantages of low material loss, low cost, and high speed.

[0004] Applying 3D printing technology to battery manufacturing shortens ion transport distances, increases electrochemical active area, and reduces interfacial impedance by constructing complex three-dimensional electrode and electrolyte structures. Existing 3D printed battery technologies primarily employ direct-write ink (DIW) and solid-state photopolymerization (SLA) processes. Patent CN 114069024 A discloses a direct-write ink (DIW) process for printing a solid electrolyte on a separator, which is then combined with a traditional coating process to prepare the positive electrode and assembled into a solid-state battery. Patent CN 114103115A uses a solid-state photopolymerization (SLA) process to print electrodes and assemble them into a battery.

[0005] However, printing using either of these two processes presents at least the following problems:

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

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

[0008] (3) Both processes are complicated, time-consuming and inefficient in post-processing.

[0009] Due to the limited flow rate of the printhead, melt-forming printing technology is relatively inefficient. Taking the printing of 1.75mm diameter polylactic acid (PLA) wire as an example, with a typical PLA flow rate of 20cc / h, it takes 12.7 hours to print a package of bare battery cells measuring 269mm*95mm*10mm according to the German Association of the Automotive Industry (VDA) standard.

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

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

[0012] To address the aforementioned issues, this invention provides a method for integrally printing solid-state batteries. Utilizing melt-forming printing technology, a 3D chamber structure of electrolyte and casing is fabricated. Positive and negative electrode slurries are then injected into the 3D chamber structure, fixing the positive and negative electrodes into shape and forming a three-dimensional positive and negative electrode structure. The solid-state battery is integrally formed, requiring no assembly, possessing a three-dimensional electrode structure, and offering a high degree of customization in shape. Because the casing and electrolyte occupy a small proportion of the solid-state battery's volume, the printing volume is significantly reduced, improving the solid-state battery printing efficiency.

[0013] A method for integrally printing solid-state batteries includes the following steps:

[0014] Step S1: Heat the electrolyte raw material, stir and blend to form a solid electrolyte printing precursor; add the shell raw material, stir and blend to form a solid shell printing precursor.

[0015] Step S2: Prepare the positive electrode slurry;

[0016] Step S3: Prepare the negative electrode slurry;

[0017] Step S4: Design an integrated 3D chamber structure of electrolyte and shell using 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, forming an inner chamber. The electrolyte 2 is located inside the inner chamber and connected to the shell 1, dividing the inner chamber into multiple slots. The slots include positive electrode slots 4 and negative electrode slots 3. Use 3D printing slicing software to slice the 3D chamber structure to form a slice file.

[0018] Step S5: Using fused deposition modeling (FDM) technology, the electrolyte-shell integrated 3D chamber structure is printed into an electrolyte-shell integrated 3D chamber structure mold; the solid electrolyte printed by FDM technology has self-supporting capabilities;

[0019] Step S6: Insert the current collector into the slot; inject the positive electrode slurry and negative electrode slurry into the positive electrode slot 4 and negative electrode slot 3 respectively; under the control of the 3D chamber structure mold, the positive electrode slurry and negative electrode slurry are fixed and formed to form a three-dimensional structure, and a three-dimensional solid-state battery prototype is made.

[0020] Step S7: Dry the battery, remove the outer casing 1, and produce a solid-state battery bare cell;

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

[0022] Solid electrolytes printed by melt-forming printing technology have 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-1,4-cyclohexanediol ester (PETG), and polylactic acid (PLA).

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

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

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

[0028] Preferably, the outer shell material is a different thermoplastic polymer from the solid electrolyte matrix. For example, it has a different coefficient of thermal expansion than the positive and negative electrodes, which facilitates the subsequent removal of the outer shell.

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

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

[0031] For the example, polyethylene terephthalate-1,4-cyclohexanediol (PETG) can be used, which is a commercially available printing material, and the printed shell wall thickness is 0.4-2 mm.

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

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

[0034] Preferably, the printing method in step S5 is printing by switching between dual printheads.

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

[0036] Preferably, the gap between adjacent electrolytes is 1 micrometer to 999 micrometers.

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

[0038] The number of electrolyte layers is set as needed, and the shape of the electrolyte is determined as needed.

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

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

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

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

[0043] Preferably, the drying method in step S7 is vacuum oven drying, and the drying temperature is 80-180℃.

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

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

[0046] (1) Using fused deposition modeling (FDM) technology, a 3D chamber structure of electrolyte and shell is printed in one piece. The positive electrode slurry and negative electrode slurry are fixed and formed under the control 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 solid-state batteries is improved.

[0047] (2) By using fused deposition modeling technology, the positive and negative electrodes can be prepared without the use of printing inks or photocuring agents with added electrochemical inertness, which can significantly improve the energy density.

[0048] (3) Electrolyte-shell 3D chamber structure utilizes the self-supporting characteristics of the electrolyte-shell to form complex positive and negative electrode slots to accommodate positive and negative electrode slurries, increase the contact area between the electrolyte and the positive and negative electrodes, shorten the ion transport distance, and reduce the interface impedance.

[0049] (4) Solid-state batteries are integrally molded, requiring no assembly, and have a complex three-dimensional electrode structure with a high degree of customization in appearance. Attached Figure Description

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

[0051] Figure 2 This is a flowchart of a solid-state battery printing process.

[0052] In the diagram, 1 represents the outer shell; 2 represents the electrolyte; 3 represents the negative electrode tank; 4 represents the positive electrode tank; 5 represents the slurry injection mechanism; 6 represents the negative electrode nozzle; and 7 represents the positive electrode nozzle. Detailed Implementation

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, embodiments are provided.

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

[0055] Example 1:

[0056] The process of printing a solid-state battery in one piece 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 silica powder in a mass ratio of 49:25:25:1. Heat to 200℃, melt-blend, and extrude into a linear printing precursor with a diameter of 1.75 mm. Add the shell material polyethylene terephthalate-1,4-cyclohexanediol ester (PETG), stir, blend, and extrude to form a solid shell printing precursor with a shell wall thickness of 0.4–2 mm.

[0058] Step S2: Prepare the positive electrode slurry. At 20°C, add polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) to make the solid content reach 5% by mass. Stir for 4 hours, then add conductive carbon black and lithium iron phosphate to make the mass ratio of lithium iron phosphate:polyvinylidene fluoride (PVDF):conductive carbon black 96:2:2. Continue stirring for 4 hours to complete the preparation of the positive electrode slurry. Vacuum degassing and storage are then performed.

[0059] Step S3: Prepare the negative electrode slurry. At 20°C, add sodium carboxymethyl cellulose (CMC) to water to make the solid content reach 1.5% by mass. Stir for 4 hours, then add conductive carbon black and graphite to make the graphite:CMC:conductive carbon black mass ratio 95:3:2. Continue stirring for 4 hours to complete the preparation of the negative electrode slurry. Vacuum degassing and storage.

[0060] Step S4: Design an integrated 3D chamber structure of electrolyte and shell using computer software. The 3D chamber structure includes shell 1 and electrolyte 2. Shell 1 is located on the periphery of the structure and surrounds to form an inner chamber. Electrolyte 2 is located inside the inner chamber and is connected to shell 1, dividing the inner chamber into multiple slots. The slots include positive electrode slot 4 and negative electrode slot 3. Use 3D printing slicing software to slice the 3D chamber structure to form a slice file.

[0061] Step S5: Using fused deposition modeling (FDM) technology, a 3D chamber structure mold integrating the electrolyte and outer shell is printed using a print head.

[0062] Step S6: Insert the current collector into the slot; inject the positive electrode slurry and negative electrode slurry into the positive electrode slot 4 and negative electrode slot 3 respectively through the positive electrode nozzle and negative electrode nozzle; use a 3D chamber structure mold to shape and fix the positive electrode slurry and negative electrode slurry to form a three-dimensional structure; and make a solid-state battery prototype.

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

[0064] Step S8: Hot-press and encapsulate the bare solid-state battery cell to form a solid-state battery.

[0065] Example 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 silica powder in a mass ratio of 49:25:25:1. Heat to 200℃, melt-blend, and extrude into a linear printing precursor with a diameter of 1.75 mm. Add the shell material polyethylene terephthalate-1,4-cyclohexanediol ester (PETG), stir, blend, and extrude to form a solid shell printing precursor with a shell wall thickness of 0.4–2 mm.

[0067] Step S2: Prepare the positive electrode slurry. At 20°C, add polyvinylidene fluoride (PVDF) to N-methylpyrrolidone (NMP) to make the solid content reach 5% by mass. 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 96:2:2. Continue stirring for 4 hours to complete the preparation of the positive electrode slurry. Vacuum degassing and storage.

[0068] Step S3: Prepare the negative electrode slurry. At 20°C, add sodium carboxymethyl cellulose (CMC) to water to make the solid content reach 1.5% by mass. Stir for 4 hours, then add conductive carbon black and graphite to make the graphite:CMC:conductive carbon black mass ratio 95:3:2. Continue stirring for 4 hours to complete the preparation of the negative electrode slurry. Vacuum degassing and storage.

[0069] Step S4: Design an integrated 3D chamber structure of electrolyte and shell using computer software. The 3D chamber structure includes a shell and an electrolyte. The shell is located on the periphery of the structure and surrounds to form an inner chamber. The electrolyte consists of two layers, located inside the inner chamber and connected to the shell. The inner chamber is divided into three slots, including a positive electrode slot and a negative electrode slot. Use 3D printing slicing software to slice the 3D chamber structure to form a slice file.

[0070] Step S5: Using fused deposition modeling (FDM) technology, a 3D chamber structure mold integrating the electrolyte and outer shell is printed by switching consumables.

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

[0072] Step S7: Transfer the battery to a vacuum oven and dry it at 90°C for 30 minutes. After the battery cools to room temperature, remove the outer casing to produce a solid-state battery cell.

[0073] Step S8: Hot-press and encapsulate the bare solid-state battery cell to form a solid-state battery.

[0074] Comparative Example 1:

[0075] According to existing technology, using direct-write ink technology, solid electrolyte, positive electrode, and negative electrode are printed simultaneously, and other steps are the same as in Example 1.

[0076] Cyclic battery testing and battery capacity testing were conducted using a Blue Battery Tester. Comparison results between Example 1 and Comparative Example 1 show that the technical solution of this invention significantly reduces solid-state battery printing time by reducing the amount of printing; and by using melt-forming printing technology, avoiding the use of electrochemically inert printing inks or photocuring agents to prepare the positive and negative electrodes, energy density can be significantly improved.

[0077] As can be seen from Example 2, this patent facilitates the fabrication of bipolar solid-state batteries.

[0078] Table 1 Comparison of results between the examples and comparative examples.

[0079]

[0080] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for integrally printing a solid-state battery, comprising the following steps: Step S1: Heat the electrolyte raw material, stir and blend it to form a solid electrolyte printing precursor by extrusion; heat the shell raw material, stir and blend it to form a solid shell printing precursor by extrusion. Step S2: Prepare the positive electrode slurry; Step S3: Prepare the negative electrode slurry; Step S4: Design an integrated 3D chamber structure of electrolyte and shell using 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 to form an inner chamber. The electrolyte (2) is located inside the inner chamber and is connected to the shell (1), dividing the inner chamber into multiple slots. The slots include positive electrode slots (4) and negative electrode slots (3). Use 3D printing slicing software to slice the 3D chamber structure to form a slice file. Step S5: Using melt-printing technology, print the electrolyte-shell integrated 3D chamber structure into an electrolyte-shell integrated 3D chamber structure mold; Step S6: Insert the current collector into the slot; inject the positive electrode slurry and the negative electrode slurry into the positive electrode slot (4) and the negative electrode slot (3) respectively; the positive electrode slurry and the negative electrode slurry are fixed and formed under the control of the 3D chamber structure mold to form a three-dimensional structure and make a three-dimensional solid battery prototype. Step S7: Dry the initial solid-state battery product, remove the outer casing (1), and produce a bare solid-state battery cell; Step S8: Package the bare solid-state battery cells to form 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 thermoplastic polymer electrolyte matrix and 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 the following: polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride, polymethyl methacrylate, polyether, acrylonitrile butadiene styrene copolymer (ABS), polyethylene terephthalate-1,4-cyclohexanediol ester (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 alumina, 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 outer shell material is one or more of acrylonitrile butadiene styrene copolymer (ABS), polyethylene terephthalate-1,4-cyclohexanediol ester (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 electrolyte (2) has 2 layers. A stainless steel bipolar current collector is inserted into the middle slot to divide 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, with a drying temperature of 80℃~180℃; the encapsulation method in step S8 is hot pressing, with a pressure of 5Psi~20Psi, a temperature of 50℃~200℃, and a time of 1min~30min.

9. A one-piece printed solid-state battery, characterized in that, Made by the method according to claim 1.

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