A lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology

Abstract

The present application relates to the technical field of deformed battery energy storage devices, and relates to a lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology, wherein first, lithium ion battery electrode active materials, a conductive agent, a binder and a solvent are mixed according to a certain mass ratio to prepare printing electrode ink. The ink is loaded into a direct writing 3D printer, and in-situ freezing technology is used as an auxiliary to design and print a macroscopic snakelike bionic structure on a copper plate immersed in liquid nitrogen. After post-processing such as freeze-drying, a multi-scale electrode with a directional pore structure on a microscale and a macroscopic snakelike bionic structure is finally obtained. The multi-scale bionic structure electrode has excellent deformation capability and can realize 300% super-stretching, 180-degree twisting and 360-degree bending. The electrode also has high area specific capacity, good cycle stability and rate performance. The method for preparing the deformed electrode by using the directional freezing assisted 3D printing technology proposed in the present application has low cost, simple operation and wide application range, and has great application potential.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deformed battery energy storage devices, in particular to a lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology. BACKGROUND

[0002] The emergence of flexible electronic devices, wearable devices and implantable medical devices has completely changed people's daily life, and the demand for high-performance flexible batteries is increasing. At present, one of the main challenges in developing flexible batteries is to design and quickly and low-cost manufacture electrodes that can still maintain excellent mechanical durability and electrochemical performance under deformation. However, the traditional electrode preparation method has complex process, high cost, is not environmentally friendly and the battery performance is general, which makes it difficult to realize the efficient development of flexible batteries.

[0003] 3D printing technology (also known as additive manufacturing) is a new technology for manufacturing 3D functional devices, which can manufacture flexible devices with complex geometry through layer-by-layer assembly based on digital 3D models. The flexible electronic devices of 3D printing not only have complex geometry and excellent mechanical properties, but also can meet various individual needs and can be produced on demand anywhere. Therefore, 3D printing technology provides great opportunities for the development of electronic devices in various fields from bionic devices to soft robots.

[0004] In order to further improve the deformability and energy density of micro batteries, macro bionic structure design inspired by nature has great potential in enhancing the multi-scale deformation of electrodes. The bionic design in the microstructure can also enhance the electrochemical performance of the electrode. However, the complex structure of the bionic structure deformed electrode brings great challenges to manufacturing. 3D printing technology can meet the flexible design of electrode structure, but the preparation of micro complex structure requires higher control precision and higher requirements for printing ink materials, thereby increasing the cost and difficulty of manufacturing. SUMMARY

[0005] The purpose of the present application is to propose a lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology to solve the problems in the background art. The method of preparing lithium ion battery electrode by 3D printing proposed in the present application is novel, simple in process and low in cost, and can realize the arbitrary of multi-scale geometry and microstructure of the electrode, which has important application value for developing high-performance flexible batteries.

[0006] The technical scheme of the present application is a lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology, and the bionic structure deformed electrode is an electrode with mechanical flexibility of stretching, twisting, bending or combination thereof.

[0007] The macrostructure of the bionic structure deformed electrode includes a snake shape, a scale shape, a grid shape, a wave shape or a spring shape; and the microstructure of the bionic structure deformed electrode has directional holes, and the directional holes grow from bottom to top to form vertical microchannels inside the plant body.

[0008] The preparation method of the bionic structure deformed electrode comprises the following steps:

[0009] S1, mixing lithium ion battery electrode active material, conductive agent, binder and solvent according to a certain mass ratio, and stirring and grinding treatment to prepare a printing electrode ink;

[0010] S2, loading the printing electrode ink into an ink direct writing 3D printer, using in-situ freezing technology as an auxiliary, designing and printing on a copper plate immersed in liquid nitrogen;

[0011] S3, designing and printing a macro bionic structure electrode;

[0012] S4, freezing and drying the printed electrode to obtain a multi-scale electrode with directional hole structure in microscale and macro bionic structure.

[0013] Preferably, the electrode active material in S1 is selected from lithium iron phosphate, lithium manganate, lithium titanate, lithium nickel cobalt manganate or a combination thereof.

[0014] Preferably, the conductive agent in S1 is selected from carbon nanotubes, graphene, carbon black or a combination thereof.

[0015] Preferably, the binder in S1 is selected from cellulose nanofiber, sodium alginate or a combination thereof; and the solvent is water.

[0016] Preferably, the mass ratio of the active material, the conductive agent and the binder in S1 is 4-6:2-4:1-3.

[0017] Preferably, the magnetic stirrer is used for stirring for 1-12 hours in S1 to fully mix, and the viscosity of the ink is adjusted by evaporating an appropriate amount of solvent through grinding.

[0018] Preferably, the nozzle diameter of the ink direct writing 3D printer in S2 is 50-1600um, the printing pressure is 10-120psi, and the needle speed is 1-50mm / s.

[0019] Preferably, the temperature of the liquid nitrogen copper sheet in S2 ranges from-100℃ to-10℃.

[0020] Preferably, the freezing and drying time in S4 is 1-12h, and the freezing and drying temperature is-10--50℃.

[0021] Preferably, in S4, the freezing of water in the ink is initiated by the low temperature of the liquid nitrogen transferred to the copper plate during the 3D printing process assisted by the directional freezing technology, and the temperature gradient causes the microstructure ice crystals to grow from bottom to top, forming vertical microchannels similar to the internal structure of plants.

[0022] Preferably, the prepared lithium ion battery multiscale biomimetic structure deformation electrode has a super tensile of 300%, a 180-degree twist and a 360-degree bending capability.

[0023] Preferably, the electrode has high area specific capacity, good cycle stability and rate performance.

[0024] Compared with the prior art, the present application has the following beneficial technical effects:

[0025] 1. Excellent deformation capability and electrochemical performance: Compared with the traditional planar lithium ion battery electrode, the method of preparing a lithium ion battery multiscale biomimetic structure deformation electrode by the 3D printing technology provided by the present application can realize the deformation of super tensile, twist, bending and their combination, while maintaining good electrochemical performance.

[0026] 2. Simplified process and low cost: The present application provides a 3D printing method assisted by directional freezing technology, which is simple in process and low in cost, and is suitable for mass production.

[0027] 3. Realization of biomimetic design: Taking flexible organisms such as snakes in nature as the biomimetic model, the biomimetic design is combined with 3D printing to successfully prepare a biomimetic 3D printed flexible electrode, which simplifies the design difficulty of the 3D printing model and enhances the deformation capability and high area load of the battery.

[0028] 4. Optimized microstructure: Taking the vertical microchannels in the internal structure of a tree as the biomimetic model, the directional freezing technology is combined to realize the preparation of the electrode microstructure, which can shorten the ion transmission distance, promote ion transmission and adapt to volume change, and improve the electrochemical performance of the battery.

[0029] 5. Adjustable macroscopic geometric structure: The electrode prepared by the method of the present application has an adjustable macroscopic geometric structure, which further enhances the deformation of the battery by imitating the deformation capability of other organisms.

[0030] 6. Adjustable microporous structure: By adjusting the proportion of raw materials, the temperature of directional freezing and the drying time, the electrode prepared by the method of the present application has an adjustable microporous structure, which can change the number and size of the microporous structure distribution.

[0031] 7. Wide applicability: The method of preparing the lithium ion battery electrode provided by the present application is also applicable to the preparation of electrodes of other battery systems. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Microscopic SEM image of a 3D-printed biomimetic deformable electrode for a lithium-ion battery.

[0033] Figure 2 A macroscopic serpentine structure diagram of a biomimetic deformable electrode for a 3D-printed lithium-ion battery;

[0034] Figure 3 Macroscopic geometric structure diagram of a 3D-printed biomimetic deformable electrode for lithium-ion batteries;

[0035] Figure 4 BET pore size distribution of the deformable electrode of the biomimetic structure for 3D-printed lithium-ion batteries;

[0036] Figure 5 Performance testing of deformable electrodes for 3D-printed biomimetic structures in lithium-ion batteries Figure 1 ;

[0037] Figure 6 Performance testing of deformable electrodes for 3D-printed biomimetic structures in lithium-ion batteries Figure 2 . Detailed Implementation

[0038] Example 1

[0039] A biomimetic deformable electrode for lithium-ion batteries, fabricated using 3D printing technology, comprises the following steps:

[0040] 1. Mix lithium iron phosphate, carbon nanotubes, cellulose nanofibers and water in a mass ratio of 4:2:1, stir for 6 hours and grind until the viscosity is suitable to prepare printing electrode ink.

[0041] 2. Load the printing electrode ink into the direct-write 3D printer, with a nozzle diameter of 100 micrometers, a printing pressure of 20 psi, and a needle speed of 10 mm / s. Perform in-situ cryogenic printing on a liquid nitrogen copper plate at -80℃.

[0042] 3. Print the snake-shaped biomimetic electrode and freeze-dry it for 10 hours at -40℃.

[0043] 4. Obtain multi-scale electrodes with microscopic oriented pore structures and macroscopic serpentine biomimetic structures.

[0044] Example 2

[0045] A biomimetic deformable electrode for lithium-ion batteries, fabricated using 3D printing technology, comprises the following steps:

[0046] 1. Mix lithium manganese oxide, graphene, sodium alginate and water in a mass ratio of 5:3:2, stir for 8 hours and grind until the viscosity is suitable to prepare printing electrode ink.

[0047] 2. The printing electrode ink is loaded into a direct writing 3D printer, the nozzle diameter is 200 microns, the printing pressure is 30 psi, the needle speed is 20 mm / s, and the in-situ freeze printing is carried out on a liquid nitrogen copper plate at -70℃.

[0048] 3. The printing scale biomimetic structure electrode is freeze-dried for 8 hours at a temperature of -30℃.

[0049] 4. A multi-scale electrode with microscopically oriented pore structure and macroscopically scale biomimetic structure is obtained.

[0050] Example 3

[0051] A lithium ion battery biomimetic structure deformed electrode prepared based on 3D printing technology, the preparation method comprising the following steps:

[0052] 1. Lithium titanate, carbon black, cellulose nanofiber and water are mixed in a mass ratio of 6:4:3, stirred for 4 hours, and ground to a suitable consistency to prepare a printing electrode ink.

[0053] 2. The printing electrode ink is loaded into a direct writing 3D printer, the nozzle diameter is 300 microns, the printing pressure is 40 psi, the needle speed is 15 mm / s, and the in-situ freeze printing is carried out on a liquid nitrogen copper plate at -60℃.

[0054] 3. The printing grid biomimetic structure electrode is freeze-dried for 12 hours at a temperature of -20℃.

[0055] 4. A multi-scale electrode with microscopically oriented pore structure and macroscopically grid-shaped biomimetic structure is obtained.

[0056] Example 4

[0057] A lithium ion battery biomimetic structure deformed electrode prepared based on 3D printing technology, the preparation method comprising the following steps:

[0058] 1. Lithium nickel cobalt manganese oxide, carbon nanotubes, sodium alginate and water are mixed in a mass ratio of 4:2:2, stirred for 12 hours, and ground to a suitable consistency to prepare a printing electrode ink.

[0059] 2. The printing electrode ink is loaded into a direct writing 3D printer, the nozzle diameter is 400 microns, the printing pressure is 50 psi, the needle speed is 25 mm / s, and the in-situ freeze printing is carried out on a liquid nitrogen copper plate at -50℃.

[0060] 3. The printing wave-shaped biomimetic structure electrode is freeze-dried for 6 hours at a temperature of -30℃.

[0061] 4. A multi-scale electrode with microscopically oriented pore structure and macroscopically wave-shaped biomimetic structure is obtained.

[0062] Example 5

[0063] A lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology, the preparation method comprising the following steps:

[0064] 1. Lithium iron phosphate, graphene, cellulose nanofiber and water are mixed in a mass ratio of 5:3:1, stirred for 6 hours, and ground to a suitable consistency to prepare a printing electrode ink.

[0065] 2. The printing electrode ink is loaded into a direct writing 3D printer, the nozzle diameter is 500 microns, the printing pressure is 60 psi, the needle speed is 30 mm / s, and in-situ freeze printing is carried out on a liquid nitrogen copper plate at -40℃.

[0066] 3. The spring-shaped bionic structure electrode is printed, freeze-dried for 10 hours, and the temperature is -40℃.

[0067] 4. A multi-scale electrode with micro directional pore structure and macro spring-shaped bionic structure is obtained.

[0068] Example 6

[0069] A lithium ion battery bionic structure deformed electrode prepared based on 3D printing technology, the preparation method comprising the following steps:

[0070] 1. Lithium titanate, carbon black, sodium alginate and water are mixed in a mass ratio of 4:2:1, stirred for 8 hours, and ground to a suitable consistency to prepare a printing electrode ink.

[0071] 2. The printing electrode ink is loaded into a direct writing 3D printer, the nozzle diameter is 600 microns, the printing pressure is 70 psi, the needle speed is 35 mm / s, and in-situ freeze printing is carried out on a liquid nitrogen copper plate at -30℃.

[0072] 3. The spring-shaped bionic structure electrode is printed, freeze-dried for 10 hours, and the temperature is -40℃.

[0073] 4. A multi-scale electrode with micro directional pore structure and macro spring-shaped bionic structure is obtained.

[0074] The electrodes prepared in Examples 1-6 are tested for performance,

[0075] Deformation capacity test steps:

[0076] First, the electrodes printed in Examples 1-6 are fixed on the test fixture, and the electrodes are sequentially subjected to machine stretching, twisting and bending; then the test value when the printed electrode completely recovers to the original state without macroscopic damage when the external force is released is taken as the deformation capacity value; take the average value after testing and recording three times; further use finite element software to carry out finite element analysis (FEA) to study the strain behavior of the bionic structure deformed electrode under various deformation states.

[0077] Electrochemical performance test steps:

[0078] The printed electrodes and commercial lithium foils were used as electrodes directly, Celgard 2500 was used as the separator, and 1M LiPF6 was used as the electrolyte. The coin cells were assembled in an argon-filled glove box and sealed with a hydraulic crimper. The electrochemical performance tests and electrochemical data were collected with a LAND test system.

[0079] The test results are shown in the following table:

[0080] Table 1. Example parameters and electrode performance

[0081]

[0082]

[0083] The analysis of the experimental data in Table 1 shows that the electrode deformation capability test can achieve a maximum range of 300% stretching, 180-degree twisting, and 360-degree bending deformation, and fully recovers to the original state without macroscopic damage after releasing external force. The finite element analysis of the electrode shows that the maximum strain under the above deformation conditions is less than the ultimate strain of the material. It shows that the electrode prepared by the method can realize the deformation of super stretching, twisting, bending and their combination, while maintaining good electrochemical performance.

[0084] As shown in Figure 4 , by adjusting the proportion of raw materials, the temperature of directional freezing, and the drying time, the electrode prepared by the method has an adjustable microporous structure, which can change the number and size of the microporous structure distribution.

[0085] As shown in Figure 5 , compared with non-directional electrodes, directional microchannel electrodes have higher specific capacity, better cycle stability, and higher rate performance. These excellent performances highlight the advantages of directional microporous electrodes, that is, to promote the rapid transmission of ions and maintain the integrity of the structure during long-term charging / discharging. As shown in Figure 6 , the high area utilization of the serpentine structure significantly improves the area capacity, providing considerable advantages for improving the overall performance of deformable batteries, and also reflecting the practicality of flexible electrodes.

[0086] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited thereto, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the present application.

Claims

1. A biomimetic deformable electrode for lithium-ion batteries based on 3D printing technology, characterized in that, Bionic deformable electrodes are electrodes with various mechanical flexibility, including stretching, torsion, bending, or combinations thereof; The macroscopic structure of the biomimetic deformable electrode includes snake-shaped, scale-shaped, grid-shaped, wave-shaped, or spring-shaped structures; the microstructure of the biomimetic deformable electrode has directional pores, which grow from bottom to top to form vertical microchannels that mimic the interior of a plant. The fabrication methods for biomimetic deformable electrodes include: S1. Lithium-ion battery electrode active material, conductive agent, binder and solvent are mixed in a certain mass ratio and stirred and ground to prepare printing electrode ink; the mass ratio of active material, conductive agent and binder in S1 is 4~6 : 2~4 : 1~3; S2. The printing electrode ink is loaded into the ink direct writing 3D printer. In-situ freezing technology is used as an aid to design and print on a copper plate immersed in liquid nitrogen. The temperature range of the liquid nitrogen copper plate in S2 is -100℃ to -10℃. S3. Design and print macroscopic biomimetic structure electrodes; S4. The printed electrodes are freeze-dried to obtain multi-scale electrodes with directional pore structures at the microscale and macroscopic biomimetic structures; the freeze-drying time in S4 is 1~12 h and the freeze-drying temperature is -10~-50℃.

2. The lithium-ion battery biomimetic deformable electrode based on 3D printing technology according to claim 1, characterized in that, The electrode active material in S1 is selected from lithium iron phosphate, lithium manganese oxide, lithium titanate, lithium nickel cobalt manganese oxide, or a combination thereof.

3. The lithium-ion battery biomimetic deformable electrode based on 3D printing technology according to claim 1, characterized in that, The conductive agent in S1 is selected from carbon nanotubes, graphene, carbon black, or a combination thereof.

4. The lithium-ion battery biomimetic deformable electrode based on 3D printing technology according to claim 1, characterized in that, The binder in S1 is selected from cellulose nanofibers, sodium alginate, or a combination thereof; the solvent is water.

5. The lithium-ion battery biomimetic deformable electrode based on 3D printing technology according to claim 1, characterized in that, When stirring in S1, use a magnetic stirrer to stir for 1 to 12 hours to ensure thorough mixing, and adjust the viscosity of the ink by grinding and evaporating an appropriate amount of solvent.

6. The lithium-ion battery biomimetic deformable electrode based on 3D printing technology according to claim 1, characterized in that, The S2 inkjet direct-write 3D printer has a nozzle diameter of 50-1600 μm, a printing pressure of 10-120 psi, and a needle speed of 1-50 mm / s.

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