Preparation method of lithium ion battery

Abstract

The invention relates to the technical field of electrochemical energy storage devices, in particular to a preparation method of a lithium ion battery, which comprises the following steps of: processing molybdenum metal foil by adopting an electric spark etching technology, and generating a current collector with molybdenum-based metal oxide on the surface of the molybdenum metal foil; and manually splicing the positive current collector, the lithium sheet, the gasket, the shell and the diaphragm together, and injecting special electrolyte to form the lithium ion button cell. The technology is simple and convenient, is non-toxic, does not need additives, and does not need to prepare pre-machined parts step by step. The prepared lithium ion button cell has excellent charge storage capacity and high specific capacitance, and a reliable basis is provided for large-scale manufacturing of the lithium ion button cell in the future.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical energy storage devices, in particular to a method for preparing a lithium ion battery. Background Art

[0002] At present, the demand for high-performance secondary batteries is growing rapidly in many fields such as power tools, electric vehicles, digital technology, communication equipment and advanced medical equipment. In order to meet the market's growing high-standard demand for energy storage devices in terms of capacity, durability and charge and discharge efficiency, the research and development and application of lithium-ion batteries have become a hot spot pursued by the global scientific and technological community. With its excellent capacity advantages, long service life, no memory effect and stable cycle performance, lithium-ion batteries have shown broad and in-depth application prospects in the fields of energy storage system construction, new energy vehicle driving and portable electronic equipment power supply.

[0003] However, there are also some technical problems in the rapid development and continuous innovation of lithium-ion battery technology. For example, the energy density of existing lithium-ion batteries is close to the theoretical limit, which is difficult to meet the high energy demand in the future. To solve this problem, it is necessary to develop high-capacity and high-voltage positive electrode materials. In addition, the traditional lithium-ion battery manufacturing technology is complex and costly, which is not conducive to large-scale production. The quality-to-capacity bottleneck of positive electrode materials has become increasingly prominent, becoming a key factor limiting the leapfrog improvement of battery energy density. Therefore, the optimal selection of positive electrode materials and the innovation of their manufacturing technology play a vital role in the research and development and production of lithium-ion batteries.

[0004] There are many different cathode materials on the market today. Although these materials, such as Prussian blue analogs, embedded transition metal sulfides and petroleum coke, show different advantages, they all encounter significant challenges in practical applications. Specifically, Prussian blue analogs are difficult to fully realize their performance potential due to the instability of their chemical structure, which limits the promotion of lithium-ion batteries in large-scale commercial applications. The volume changes of embedded transition metal sulfides during the insertion and extraction of lithium ions seriously affect the cycle stability and long-term service life of the battery, causing the battery performance to gradually decline over time, all of which limit the large-scale commercial application of lithium-ion batteries.

[0005] In addition to the selection of positive electrode materials, existing manufacturing technologies also face many challenges in this field of lithium-ion batteries. First of all, as a traditional mainstream manufacturing process, photolithography has high precision, but its shortcomings are also significant. High equipment investment, complex process flow and strict requirements for the operating environment have increased manufacturing costs and time cycles. More importantly, the photoresist contamination problem generated during the photolithography process not only has a negative impact on the environment, but also increases the difficulty and cost of subsequent cleaning work. On the other hand, in addition to photolithography, although the screen printing method has shown flexibility in some aspects, its process for preparing high-quality composite material printing inks is cumbersome and technically difficult, and the adhesion between the electrode active material and the substrate is insufficient. It is often necessary to add a large amount of surfactants, adhesives and other harmful solvents to regulate the properties of the printing ink, which not only increases the uncertainty in the manufacturing process and reduces the electrochemical performance of the electrode, but also further increases the cost. At the same time, the use of these additives may also have an adverse effect on the performance stability and environmental friendliness of the product. In addition, other traditional manufacturing technologies such as inkjet printing, although improved in graphics accuracy and efficiency, still face problems such as poor material adaptability and easy nozzle clogging, and are difficult to be widely used in the large-scale production of lithium-ion batteries. To this end, the present invention proposes a method for preparing a lithium-ion battery to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a lithium ion battery to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: a method for preparing a lithium-ion battery, adopting a high-precision CNC electric spark wire cutting machine vertical cutting process to prepare a 3D current collector, the positive electrode material uses a molybdenum sheet as a substrate, and a MoxOy-based oxide grows on the surface after electric spark etching, and the etched Mo-MoxOy substrate is cut into a circular pattern by an electric spark wire cutting machine, and the processed Mo-MoxOy, circular lithium sheet, shell, gasket, and diaphragm are manually spliced ​​together. When the diaphragm is placed between the electrodes, LB-153 electrolyte needs to be injected on both sides of the diaphragm, and then assembled to obtain a lithium-ion battery with excellent electrochemical performance;

[0008] The preparation method of lithium ion battery, the specific preparation steps are as follows:

[0009] Step 1:

[0010] Clean the surface of the molybdenum sheet 2-3 times to remove the pollutants adsorbed on the material. After cleaning, place the sample in a 50°C constant temperature drying oven for 5 minutes;

[0011] Step 2:

[0012] After drying, the molybdenum sheet is mounted on the horizontal fixture of the CNC wire-cut EDM machine, and the rectangular sheet cutting program drawn by the drawing program is called up, and the processing parameters are set: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4, and then the CNC wire-cut EDM machine is started to cut the rectangular sheet;

[0013] Step 3:

[0014] The rectangular sheet is placed on the longitudinal fixture of the machine tool for clamping, and the two longer side surfaces of the rectangular substrate are linearly cut and etched to obtain Mo-Mo x O y Substrate: Use the straight-line cutting program to cut the two sides of the rectangular sheet parallel to the electrode wire to make the surface of Mo grow evenly. x O y , set the processing parameters: working current is 2A, working voltage is 60-100V, and interval ratio is 4;

[0015] Step 4:

[0016] Will Mo-Mo x O y The substrate is transferred to the horizontal fixture of the machine tool for clamping, and the circular pattern cutting route is called. The processing parameters are set: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4. Then the CNC EDM wire cutting machine is started to cut the Mo-Mo x O y The substrate is cut into circular electrode sheets, washed with deionized water 2-3 times, placed in a drying oven for drying and cooling, and then bagged and stored at room temperature;

[0017] Step 5:

[0018] Assemble the lithium-ion battery in the following order: positive electrode shell, positive electrode, diaphragm, negative electrode, gasket, negative electrode shell. Electrolyte LB-153 needs to be added before and after placing the diaphragm.

[0019] Step 6:

[0020] The lithium-ion battery is packaged and the assembled lithium-ion battery is placed on a small hydraulic button battery packaging machine and pressed to a pressure of 1000kg / cm 2 , which lasts for 15 seconds, and the finished lithium-ion battery is taken out;

[0021] Step 7:

[0022] The lithium-ion battery was tested using a dual-electrode test system. During the test, Mo-Mo x O yOne end is used as the working positive electrode, and the Li end is used as the working negative electrode. The prepared LB-153 solution is used as the electrolyte, and the electrochemical test is performed using cyclic voltammetry in the voltage range of 1.5-3.5V. All tests will be completed in the electrochemical workstation.

[0023] Preferably, the deionized water washing times mentioned above are 2-3 times, the constant temperature oven drying temperature is 50 degrees Celsius, the drying time is 5 minutes, the thickness of the current collector raw material base is 1mm, the rectangular parameters are 14mm*19mm, the diameter of the circular electrode sheet is 14mm, the electrolyte LB-153 is a solution of 1M LiPF6 mixed in DEC, EC and EMC in a volume ratio of 1:1:1, the cyclic voltammetry voltage range is: 1.5-3.5V, the electric spark wire cutting processing parameters are: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4.

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

[0025] The present invention introduces an innovative lithium-ion button cell based on electric spark discharge etching technology and a preparation method thereof. In this technology, electric spark discharge etching is used as the core process. By using a molybdenum electrode wire, plasma etching is performed on the surface of the workpiece at a very close distance, thereby causing the surface of the metal material to be oxidized at high temperature and realizing a precise corrosion process. This technology uniquely promotes the growth of active substances such as molybdenum oxide directly on the surface of the metal material. These newly grown active substances have become the key to the preparation of lithium-ion button cells by this technology with their excellent charge storage capacity and the introduction of no adhesive.

[0026] Compared with traditional metal lithium-ion batteries, the present invention overcomes significant problems such as dendrite growth, continuous side reactions, large volume effect, intolerance to over-discharge and over-charge, and potential risks of combustion and explosion, greatly improving the cycle life and safety of the battery. The lithium-ion button battery we proposed uses a binder-free molybdenum-based metal oxide as the positive electrode and a lithium sheet as the negative electrode, and achieves the goal of storing more energy in a limited space through a precise and reliable button-type sealing structure design. This compact structure not only ensures the high energy density of the battery, but also ensures its small size. The application of electric spark discharge etching technology realizes the rapid and efficient preparation of molybdenum-based metal oxide positive electrodes in one step, simplifies the preparation process of the positive electrode, eliminates the use of adhesives and toxic and harmful solvents, and further enhances the charge storage capacity of the lithium-ion button battery, and significantly improves its cycle stability. The use of this technology also optimizes the conductivity of the battery, providing strong support for the performance improvement and reliability assurance of lithium-ion button batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is a schematic diagram of preparing a lithium-ion button battery according to the present invention.

[0028] Figure 2 This is a scanning electron microscope (SEM) image of the molybdenum circular pole piece prepared in the present invention.

[0029] Figure 3 This is the X-ray diffraction (XRD) diagram of the molybdenum circular pole piece prepared in the present invention.

[0030] Figure 4 The specific capacity bar graph of the lithium ion button battery prepared in the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1: Please refer to Figures 1 to 4 The present invention provides a technical solution: a preparation method of a lithium-ion battery, adopting a high-precision CNC electric spark wire cutting machine vertical cutting process to prepare a 3D current collector, the positive electrode material uses a molybdenum sheet as a substrate, and a MoxOy-based oxide grows on the surface after electric spark etching, and the etched Mo-MoxOy substrate is cut into a circular pattern by an electric spark wire cutting machine, and the processed Mo-MoxOy, circular lithium sheet, shell, gasket, and diaphragm are manually spliced ​​together. When the diaphragm is placed between the electrodes, LB-153 electrolyte needs to be injected on both sides of the diaphragm, and then assembled to obtain a lithium-ion battery with excellent electrochemical performance;

[0033] The preparation method of lithium ion battery, the specific preparation steps are as follows:

[0034] Step 1:

[0035] Clean the surface of the molybdenum sheet 2-3 times to remove the pollutants adsorbed on the material. After cleaning, place the sample in a 50°C constant temperature drying oven for 5 minutes;

[0036] Step 2:

[0037] After drying, the molybdenum sheet is mounted on the horizontal fixture of the CNC wire-cut EDM machine, and the rectangular sheet cutting program drawn by the drawing program is called up, and the processing parameters are set: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4, and then the CNC wire-cut EDM machine is started to cut the rectangular sheet;

[0038] Step 3:

[0039] The rectangular sheet is placed on the longitudinal fixture of the machine tool for clamping, and the two longer side surfaces of the rectangular substrate are linearly cut and etched to obtain Mo-Mo x O y Substrate: Use the straight-line cutting program to cut the two sides of the rectangular sheet parallel to the electrode wire to make the surface of Mo grow evenly. x O y , set the processing parameters: working current is 2A, working voltage is 60-100V, and interval ratio is 4;

[0040] Step 4:

[0041] Will Mo-Mo x O y The substrate is transferred to the horizontal fixture of the machine tool for clamping, and the circular pattern cutting route is called. The processing parameters are set: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4. Then the CNC EDM wire cutting machine is started to cut the Mo-Mo x O y The substrate is cut into circular electrode sheets, washed with deionized water 2-3 times, placed in a drying oven for drying and cooling, and then bagged and stored at room temperature;

[0042] Step 5:

[0043] Assemble the lithium-ion battery in the following order: positive electrode shell, positive electrode, diaphragm, negative electrode, gasket, negative electrode shell. Electrolyte LB-153 needs to be added before and after placing the diaphragm.

[0044] Step 6:

[0045] The lithium-ion battery is packaged and the assembled lithium-ion battery is placed on a small hydraulic button battery packaging machine and pressed to a pressure of 1000kg / cm 2 , which lasts for 15 seconds, and the finished lithium-ion battery is taken out;

[0046] Step 7:

[0047] The lithium-ion battery was tested using a dual-electrode test system. During the test, Mo-Mo x O y One end is used as the working positive electrode, and the other end is used as the working negative electrode. The prepared LB-153 solution is used as the electrolyte, and the electrochemical test is performed using cyclic voltammetry in the voltage range of 1.5-3.5V. All tests will be completed in the electrochemical workstation;

[0048] The above-mentioned deionized water cleaning times are 2-3 times, the constant temperature oven drying temperature is 50 degrees Celsius, the drying time is 5 minutes, the thickness of the current collector raw material base is 1mm, the rectangular parameters are 14mm*19mm, the circular electrode sheet diameter is 14mm, the electrolyte LB-153 is a solution of 1M LiPF6 mixed in DEC, EC and EMC in a volume ratio of 1:1:1, the cyclic voltammetry voltage range is: 1.5-3.5V, the electric spark wire cutting processing parameters: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4.

[0049] As attached Figure 1 The figure shows a schematic diagram of preparing lithium-ion button batteries. In a dust-free and dry environment, first use deionized water to clean the surface of a 1mm thick molybdenum sheet 2-3 times. After removing the attached contaminants, place it in a 50°C constant temperature drying oven and dry it for 5 minutes. Subsequently, the treated molybdenum sheet is firmly clamped horizontally on a CNC electric spark wire cutting machine, with Mo wire as the working electrode wire and deionized water as the working fluid, and appropriate working parameters are set (current 2A, voltage 60V, interval ratio 4). Through CNC operation, the first rectangular block is cut using a prefabricated rectangular sheet cutting program, and adjusted to the longitudinal fixture of the machine tool for precise clamping. Next, a linear cutting program is used to perform surface cutting and etching on the two long sides of the rectangular substrate to uniformly generate Mo. x O y layer to obtain Mo-Mo x O y After that, the substrate is transferred to the horizontal fixture of the machine tool, and the circular pattern cutting route is executed to make a circular electrode sheet, which is then properly stored after being washed with deionized water, dried and cooled. Finally, the lithium-ion battery is assembled and packaged, and Mo-Mo is placed in the positive electrode shell in turn. x O y The circular pole piece, the electrolyte LB-153 is added, the diaphragm is placed, the electrolyte is added again, the lithium sheet is added as the negative electrode, fixed with a gasket and covered with the negative electrode shell. The entire battery assembly is placed on a small hydraulic button battery packaging machine and 1000kg / cm 2 The pressure lasts for 15 seconds to complete the packaging and finally obtain the finished lithium-ion button battery.

[0050] As attached Figure 2The scanning electron microscope (SEM) image shown clearly shows the unique morphology of the electrode surface, which is covered with nanoscale oxide particle clusters that are as delicate and intricate as wine lees. This microstructure gives the electrode surface a significant roughness, greatly expanding its specific surface area, creating favorable conditions for close contact between the active material and the electrolyte. At the same time, its high surface roughness effectively shortens the path of ion transmission, thereby greatly improving the electrochemical response speed of the electrode. At the same time, this nanoscale design also significantly enhances the charge storage capacity, allowing the electrode to show higher efficiency and capacity in the process of energy storage and conversion.

[0051] like Figure 3 The X-ray diffraction (XRD) analysis shown clearly reveals the core composition of the electrode surface, which is mainly composed of Mo, MoO2 and MoO3. Among them, Mo, as a strong current collector material, constructs a stable substrate framework, which not only provides excellent mechanical strength for the overall structure, but also ensures stability and durability under long-term use. As active materials, MoO2 and MoO3 significantly enhance the pseudocapacitive performance of the electrode, and effectively improve the energy storage efficiency of the material through their unique redox reaction mechanism. It is particularly striking that the coexistence of multiple valence states of MoO2 and MoO3 complexes greatly promotes the rapid transport of ions and the efficient storage of charges, thereby showing better electrochemical performance.

[0052] Attached Figure 4 The specific capacity variation trend of the prepared lithium-ion button battery under different processing voltage conditions is intuitively shown. It can be clearly observed from the figure that with the gradual adjustment of the processing voltage, especially when the voltage is set to 80V, the specific capacitance performance of the battery reaches a significant peak value of up to 100.3mF / cm 2

[0053] Embodiment 2:

[0054] Step 1:

[0055] The 1 mm thick molybdenum sheet was cleaned 2-3 times to remove the pollutants adsorbed on the material. After cleaning, the sample was placed in a 50°C constant temperature drying oven for 5 minutes.

[0056] Step 2:

[0057] Clamp the molybdenum sheet horizontally on the workbench of the CNC wire-cut EDM machine and ensure that it is clamped firmly and stably.

[0058] Step 3:

[0059] Mo wire (φ0.18 mm) was used as the working electrode wire, deionized water was used as the working fluid, the working current was set to 2 A, the working voltage was set to 80 V or 100 V, and the interval ratio was set to 4.

[0060] Step 4:

[0061] The molybdenum sheet is mounted on a transverse fixture of a CNC electric spark wire cutting machine, and a rectangular sheet cutting program drawn by a drawing program is called up, and the CNC electric spark wire cutting machine is started to cut the rectangular sheet to obtain a first rectangular block.

[0062] Step 5:

[0063] The first rectangular block is placed on the longitudinal fixture of the machine tool for clamping, and the two longer side surfaces of the rectangular substrate are linearly cut and etched to obtain Mo-Mo x O y Substrate: Use the straight-line cutting program to cut the two sides of the rectangular sheet parallel to the electrode wire to make the surface of Mo grow evenly. x O y , and obtain the second rectangular block.

[0064] Step 6:

[0065] Will Mo-Mo x O y The substrate is transferred to the horizontal fixture of the machine tool for clamping, and the circular pattern cutting route is called, and then a circular electrode sheet is obtained. It is washed with deionized water 2-3 times, sent to a drying oven for drying, cooled, and then bagged and stored at room temperature.

[0066] Step 7:

[0067] The assembly and packaging process of lithium-ion batteries includes placing Mo-Mo in the positive electrode shell in a dust-free and dry environment. x O y The circular electrode is dripped with 1M LB-153 electrolyte, then carefully placed and soaked in the diaphragm, and then the lithium sheet is added as the negative electrode, fixed with a gasket and covered with the negative electrode shell. After that, the whole battery is placed on a small hydraulic button battery packaging machine and 1000kg / cm 2 The pressure lasts for 15 seconds to complete the packaging and form a finished lithium-ion button battery.

[0068] Step 8:

[0069] Lithium-ion batteries are tested using a dual-electrode test system. x O yOne end is used as the working positive electrode, the other end is used as the working negative electrode, the prepared 1M LB-153 solution is used as the electrolyte, and the electrochemical test is performed using cyclic voltammetry in the voltage range of 1.5-3.5V. All tests will be completed in an electrochemical workstation.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a lithium ion battery, characterized in that: A 3D current collector is prepared by a high-precision CNC wire-cut EDM vertical cutting process. The positive electrode material uses a molybdenum sheet as a substrate. After EDM etching, a MoxOy-based oxide grows on the surface. The etched Mo-MoxOy substrate is cut into a circular pattern using a wire-cut EDM machine. The processed Mo-MoxOy, circular lithium sheet, shell, gasket, and diaphragm are manually spliced ​​together. When the diaphragm is placed between the electrodes, LB-153 electrolyte needs to be injected on both sides of the diaphragm, and then assembled to obtain a lithium-ion battery with excellent electrochemical performance. The preparation method of lithium ion battery, the specific preparation steps are as follows: Step 1: Clean the surface of the molybdenum sheet 2-3 times to remove the pollutants adsorbed on the material. After cleaning, place the sample in a 50°C constant temperature drying oven for 5 minutes; Step 2: After drying, the molybdenum sheet is mounted on the horizontal fixture of the CNC wire-cut EDM machine, and the rectangular sheet cutting program drawn by the drawing program is called up, and the processing parameters are set: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4, and then the CNC wire-cut EDM machine is started to cut the rectangular sheet; Step 3: The rectangular sheet is placed on the longitudinal fixture of the machine tool for clamping, and the two longer side surfaces of the rectangular substrate are linearly cut and etched to obtain Mo-Mo x O y Substrate: Use the straight-line cutting program to cut the two sides of the rectangular sheet parallel to the electrode wire to make the surface of Mo grow evenly. x O y , set the processing parameters: working current is 2A, working voltage is 60-100V, and interval ratio is 4; Step 4: Will Mo-Mo x O y The substrate is transferred to the horizontal fixture of the machine tool for clamping, and the circular pattern cutting route is called. The processing parameters are set: the working current is 2A, the working voltage is 60-100V, and the interval ratio is 4. Then the CNC EDM wire cutting machine is started to cut the Mo-Mo x O y The substrate is cut into circular electrode sheets, washed with deionized water 2-3 times, placed in a drying oven for drying and cooling, and then bagged and stored at room temperature; Step 5: Assemble the lithium-ion battery in the following order: positive electrode shell, positive electrode, diaphragm, negative electrode, gasket, negative electrode shell. Electrolyte LB-153 needs to be added before and after placing the diaphragm. Step 6: The lithium-ion battery is packaged and the assembled lithium-ion battery is placed on a small hydraulic button battery packaging machine and pressed to a pressure of 1000kg / cm 2 , which lasts for 15 seconds, and the finished lithium-ion battery is taken out; Step 7: The lithium-ion battery was tested using a dual-electrode test system. During the test, Mo-Mo x O y One end is used as the working positive electrode, and the Li end is used as the working negative electrode. The prepared LB-153 solution is used as the electrolyte, and the electrochemical test is performed using cyclic voltammetry in the voltage range of 1.5-3.5V. All tests will be completed in the electrochemical workstation.

2. The method for preparing a lithium ion battery according to claim 1, characterized in that: The above-mentioned deionized water cleaning times are 2-3 times, the constant temperature oven drying temperature is 50 degrees Celsius, the drying time is 5 minutes, the thickness of the current collector raw material base is 1mm, the rectangular parameters are 14mm*19mm, the circular electrode sheet diameter is 14mm, the electrolyte LB-153 is a solution composed of 1MLiPF6 mixed in DEC, EC and EMC in a volume ratio of 1:1:1, the cyclic voltammetry voltage range is: 1.5-3.5V, and the EDM wire cutting processing parameters are: working current is 2A, and the working voltage is 60-100V.

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