An electrode preparation method for promoting efficient ion transmission of thick electrodes

Abstract

The application provides an electrode preparation method for promoting efficient ion transmission of a thick electrode, comprising: preparing an electrode material into an initial electrode through a preset process; preparing a treatment solution, the treatment solution comprising one or more of dimethyl carbonate, a first mixture, a second mixture and a third mixture; placing the initial electrode in the treatment solution for cyclic freezing treatment; obtaining a standby electrode after several times of cyclic freezing treatment; and performing vacuum drying treatment on the standby electrode to obtain a final electrode. Due to the molecular structure and physical properties of dimethyl carbonate, ice crystals with a specific structure can be formed in the freezing process, and the arrangement and morphology of the ice crystals can affect the microstructure of the electrode material, providing a more efficient ion transmission path, i.e., providing the electrode with an optimized pore structure with higher porosity, so that the electrode can fully utilize the active material for energy conversion, improve the energy density of the battery, prolong the service life of the battery, and meet the demand for optimization of electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to an electrode preparation method that promotes efficient ion transport in thick electrodes. Background Technology

[0002] Lithium-ion batteries are one of the most widely used and fastest-growing devices in the current energy storage field. With their high energy density, long service life and environmental friendliness, they have shown great application potential in electric vehicles, mobile devices, energy storage systems and other fields.

[0003] However, with the rapid development of new energy vehicles and the increasing demands on battery performance from electronic devices, the energy density and charging speed of traditional lithium-ion batteries are no longer sufficient to meet market needs. Against this backdrop, thick electrode design, as an effective strategy to improve battery energy density, has attracted widespread attention from academia and industry in recent years.

[0004] However, increasing electrode thickness lengthens the charge transport path, increases battery internal resistance, and significantly reduces the utilization rate of active materials. Especially at high current densities (1C–5C), thick electrodes often experience a significant decline in electrochemical performance due to reduced utilization. Therefore, improving the liquid-phase transport distance of thick electrodes is an important method and means to promote efficient ion transport in thick electrodes.

[0005] To address the aforementioned issues, the cryo-electrode method has gradually emerged. This method utilizes low-temperature freezing technology to prepare lithium-ion battery electrodes. It involves freezing a mixture of active materials, conductive agents, and binders at low temperatures, followed by thawing and drying steps to obtain an electrode with a specific pore structure. While this method can produce electrodes with a porous structure that facilitates rapid lithium-ion transport, it still falls short of meeting the requirements for optimizing the electrochemical performance of lithium batteries. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide an electrode preparation method that promotes efficient ion transport in thick electrodes. This invention aims to solve the technical problem that although the existing cryogenic electrode preparation method can prepare electrodes with porous structures with porosity and improve the rapid transport of lithium ions to a certain extent, it still fails to meet the requirements of optimizing the electrochemical performance of lithium batteries.

[0007] To achieve the above objectives, embodiments of this application provide an electrode preparation method that promotes efficient ion transport in thick electrodes, comprising the following steps:

[0008] The electrode material is prepared as the initial electrode through a predetermined process;

[0009] A treatment solution is prepared, the treatment solution comprising one or more of dimethyl carbonate, a first mixture, a second mixture, and a third mixture, wherein the first mixture, the second mixture, and the third mixture all comprise dimethyl carbonate and ethanol, and the mixing ratio of dimethyl carbonate and ethanol in the first mixture, the second mixture, and the third mixture is different;

[0010] The initial electrode is placed in the processing solution for cyclic freezing treatment. After several cycles of freezing treatment, a ready-to-use electrode is obtained. The ready-to-use electrode is then subjected to vacuum drying treatment to obtain the final electrode.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: By introducing dimethyl carbonate or the first mixture, second mixture, or third mixture including dimethyl carbonate as the freezing medium in the preparation process of the cryogenic electrode, the high dielectric constant and low viscosity of dimethyl carbonate enable it to interact more effectively with the electrode material when used as a freezing medium. The high dielectric constant is beneficial to the conduction of ions in the electrolyte solution, while the low viscosity facilitates the flow and penetration of the electrolyte on the electrode surface, enabling rapid and sufficient penetration of the electrode. Due to the molecular structure and physical properties of dimethyl carbonate, it can form ice crystals with specific structures during the freezing process. The arrangement and morphology of these ice crystals can affect the microstructure of the electrode material, thereby optimizing the transport of lithium ions. Compared to traditional cryogenic electrode processes, dimethyl carbonate can form a more uniform and finer ice crystal structure, thus providing a more efficient ion transport path. This means it provides an optimized pore structure with higher porosity for the electrode, further reducing ion transport resistance and increasing the battery's charge and discharge rate. With further improvements in ion transport efficiency, the electrode can more fully utilize the active material for energy conversion, thereby increasing the battery's energy density, extending its lifespan, and meeting the needs of electrochemical performance optimization. At the same time, dimethyl carbonate has advantages such as low toxicity, low corrosivity, non-flammability, and non-explosiveness, meeting the high environmental and safety requirements of modern industry. Using dimethyl carbonate as a cryogenic medium in the production process of lithium-ion batteries can reduce environmental pollution and potential safety risks.

[0012] Furthermore, the preset process is either a dry electrode preparation process or a wet electrode preparation process.

[0013] Furthermore, the electrode material is either a positive electrode material or a negative electrode material.

[0014] Furthermore, when the electrode material is a positive electrode material, the positive electrode material includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel oxide.

[0015] Furthermore, when the electrode material is a negative electrode material, the negative electrode material includes one or more of graphite, hard carbon, soft carbon, and silicon carbon.

[0016] Furthermore, the step of placing the initial electrode in the processing solution for cyclic freezing includes:

[0017] The initial electrode is immersed in the treatment solution for a first preset time, and then the immersed initial electrode is placed in a freezer to freeze for a second preset time.

[0018] The frozen initial electrode is thawed to complete the cyclic freezing process.

[0019] Furthermore, the thickness of the initial electrode is 200µm to 600µm.

[0020] Furthermore, the first preset time is 30 min to 1440 min.

[0021] Furthermore, the second preset time is 10 min to 120 min.

[0022] Furthermore, the number of cycles is 5 to 20. Attached Figure Description

[0023] Figure 1 This is a flowchart of the electrode preparation method for promoting efficient ion transport in thick electrodes in Embodiment 1 of the present invention;

[0024] Figure 2 The image shows the contact angle test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Embodiment 1 of the present invention.

[0025] Figure 3 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Example 1 of the present invention.

[0026] Figure 4 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Example 2 of the present invention.

[0027] Figure 5 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Example 3 of the present invention.

[0028] Figure 6 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Example 4 of the present invention.

[0029] Figure 7The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Example 5 of the present invention.

[0030] Figure 8 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Comparative Example 1 of this invention.

[0031] Figure 9 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Comparative Example 2 of this invention.

[0032] Figure 10 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Comparative Example 3 of this invention.

[0033] Figure 11 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Comparative Example 4 of this invention.

[0034] Figure 12 The graph shows the electrochemical performance test results of the final electrode prepared by the electrode preparation method for promoting efficient ion transport in thick electrodes in Comparative Example 5 of this invention.

[0035] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0036] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0037] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] Please see Figure 1 and Figure 2 Embodiment 1 of the present invention provides a method for preparing an electrode that promotes efficient ion transport in thick electrodes, comprising the following steps:

[0040] S10: Prepare the electrode material into an initial electrode through a preset process;

[0041] Preferably, the preset process is a dry electrode preparation process or a wet electrode preparation process. The wet electrode preparation process is widely used in cryogenic electrode processes and will not be described in detail here. In this embodiment, the preset process is a dry electrode preparation process. Specifically, the electrode material is fiberized in a pulverizer to obtain electrode powder. The electrode powder is then dry-rolled onto the surface of the aluminum current collector using a roller coater to obtain a raw electrode. The raw electrode is then cut into several initial electrodes.

[0042] The electrode material is either a positive electrode material or a negative electrode material. Preferably, when the electrode material is a positive electrode material, it includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel oxide. When the electrode material is a negative electrode material, it includes one or more of graphite, hard carbon, soft carbon, and silicon carbon. In this embodiment, the electrode material is a positive electrode material, specifically lithium iron phosphate. Preferably, the particle size of the lithium iron phosphate is 4µm–5µm, 40µm–12µm, or 300nm–500nm. It should be noted that during the dry electrode preparation process, the lithium iron phosphate, carbon black, and PTFE are fiberized in a pulverizer at a mass ratio of 8:1:1. It is understood that traditional cryogenic electrode preparation processes generally involve wet electrode preparation processes based on slurry. However, the preparation process of this application can simultaneously adapt to both dry and wet electrode preparation processes, effectively improving the applicability of the preparation method compared to traditional methods.

[0043] Preferably, the thickness of the initial electrode is 200um to 600um. In this embodiment, the thickness of the initial electrode is 200um.

[0044] S20: Prepare the raw material into a treatment liquid, wherein the raw material is one or more of dimethyl carbonate, a first mixture, a second mixture, and a third mixture, wherein the first mixture, the second mixture, and the third mixture all include dimethyl carbonate and ethanol, and the mixing ratio of dimethyl carbonate and ethanol in the first mixture, the second mixture, and the third mixture is different;

[0045] In the first mixture, the dimethyl carbonate and ethanol are mixed in a ratio of 1:1; in the second mixture, the dimethyl carbonate and ethanol are mixed in a ratio of 1:2; and in the third mixture, the dimethyl carbonate and ethanol are mixed in a ratio of 1:3.

[0046] S30: The initial electrode is placed in the processing solution for cyclic freezing treatment. After several cycles of freezing treatment, a ready-to-use electrode is obtained. The ready-to-use electrode is then subjected to vacuum drying treatment to obtain a frozen electrode.

[0047] In this embodiment, the cyclic freezing process is repeated 5 times.

[0048] Specifically, step S30 includes:

[0049] S310: Immerse the initial electrode in the treatment solution for a first preset time, and then freeze the immersed initial electrode in a freezer for a second preset time;

[0050] In this embodiment, the first preset time is 30 minutes, and the second preset time is 10 minutes. The temperature of the freezer is -20°C.

[0051] S320: Thaw the frozen initial electrode to complete the cyclic freezing process;

[0052] In this embodiment, the frozen initial electrode is placed at room temperature for thawing.

[0053] Understandably, the electrode to be used is placed in a vacuum drying oven for vacuum drying treatment at a temperature of 80°C for a duration of 6 hours.

[0054] Please see Figure 2 After preparing the electrode according to the electrode preparation method for promoting efficient ion transport of thick electrodes described in this embodiment, the electrode is subjected to a contact angle test. It can be clearly seen that the contact angle is small during the contact angle test, indicating that the electrolyte has a good wetting speed on the electrode surface, that is, good wettability. Good wettability helps the electrolyte to fully contact the electrode material and improve the ion transport efficiency.

[0055] Example 2 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0056] The first preset time is 1440 min.

[0057] Example 3 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0058] The second preset time is 120 minutes.

[0059] Example 4 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0060] The number of cyclic freezing treatments is 20.

[0061] Example 5 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0062] The first preset time is 50 minutes, the second preset time is 60 minutes, and the number of cyclic freezing treatments is 10.

[0063] Comparative Example 1 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0064] The first preset time is 1600 min.

[0065] Comparative Example 2 of this invention provides an electrode preparation method that promotes efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0066] The second preset time is 140 minutes.

[0067] Comparative Example 3 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0068] The number of cyclic freezing treatments is 30.

[0069] Comparative Example 4 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0070] The initial electrode is used as the final electrode, meaning that subsequent steps such as preparation of the processing solution and cyclic freezing are not performed.

[0071] Comparative Example 5 of this invention provides an electrode preparation method for promoting efficient ion transport in thick electrodes, which differs from the electrode preparation method for promoting efficient ion transport in thick electrodes described in Example 1 in that:

[0072] After obtaining the initial electrode, the final electrode is prepared using a conventional cryo-electrode process.

[0073] The final electrode was prepared according to the electrode preparation method for promoting efficient ion transport in thick electrodes as described in Examples 1 to 5 and Comparative Examples 1 to 5 of this application. The final electrode was then used to assemble a CR-2032 coin-type battery in an argon-filled glove box for electrochemical performance testing. A 1M LiPF6 solution dissolved in DMC:EC:EMC = 1:1:1 vol% was used as the electrolyte in the test. Constant current charging / discharging (positive electrode: 2.5–4V; negative electrode: 0.005–3V) was measured on a testing system (Shenzhen, CT-3008W). Electrochemical impedance spectroscopy (EIS) of the battery was performed on a Parstat4000+ electrochemical workstation with an AC amplitude of 5mV in the frequency range of 100kHz to 0.01Hz. Cyclic voltammetry (CV) measurements were performed on the Parstat4000+ workstation at different scan rates (0.1–2mVs⁻¹), and the results are shown in the table below.

[0074]

[0075] Based on the table above Figures 3 to 12It is known that by introducing dimethyl carbonate or the first, second, or third mixtures containing dimethyl carbonate as the freezing medium in the preparation process of the cryogenic electrode, the high dielectric constant and low viscosity of dimethyl carbonate allow it to interact more effectively with the electrode material. The high dielectric constant facilitates ion conduction in the electrolyte solution, while the low viscosity promotes the flow and penetration of the electrolyte on the electrode surface, enabling rapid and thorough electrode penetration. Due to the molecular structure and physical properties of dimethyl carbonate, it can form ice crystals with specific structures during freezing. The arrangement and morphology of these ice crystals can affect the microstructure of the electrode material, thereby optimizing the lithium-ion transport channels, i.e., compared to traditional methods... The cryogenic electrode process allows dimethyl carbonate to form a more uniform and finer ice crystal structure, providing a more efficient ion transport path. This optimized pore structure with higher porosity further reduces ion transport resistance and increases the battery's charge and discharge rate. With improved ion transport efficiency, the electrode can more fully utilize the active material for energy conversion, thereby increasing the battery's energy density, extending its lifespan, and meeting the demands for optimized electrochemical performance. Simultaneously, dimethyl carbonate possesses advantages such as low toxicity, low corrosivity, non-flammability, and non-explosiveness, meeting the high environmental and safety requirements of modern industry. Using dimethyl carbonate as a cryogenic medium in lithium-ion battery production can reduce environmental pollution and potential safety risks. Furthermore, by controlling the process parameters of the cyclic cryogenic treatment in this application, the final electrode can be better ensured to have superior electrical performance.

[0076] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing an electrode that promotes efficient ion transport in thick electrodes, characterized in that, Includes the following steps: The electrode material is prepared as the initial electrode through a predetermined process; A treatment solution is prepared, the treatment solution comprising one or more of dimethyl carbonate, a first mixture, a second mixture, and a third mixture, wherein the first mixture, the second mixture, and the third mixture all comprise dimethyl carbonate and ethanol, and the mixing ratio of dimethyl carbonate and ethanol in the first mixture, the second mixture, and the third mixture is different; The initial electrode is placed in the processing solution for cyclic freezing treatment. After several cycles of freezing treatment, a ready-to-use electrode is obtained. The ready-to-use electrode is then subjected to vacuum drying treatment to obtain the final electrode.

2. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 1, characterized in that, The preset process is either a dry electrode preparation process or a wet electrode preparation process.

3. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 1, characterized in that, The electrode material is either a positive electrode material or a negative electrode material.

4. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 3, characterized in that, When the electrode material is a positive electrode material, the positive electrode material includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel oxide.

5. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 3, characterized in that, When the electrode material is a negative electrode material, the negative electrode material includes one or more of graphite, hard carbon, soft carbon, and silicon carbon.

6. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 1, characterized in that, The step of placing the initial electrode in the treatment solution for cyclic freezing includes: The initial electrode is immersed in the treatment solution for a first preset time, and then the immersed initial electrode is placed in a freezer to freeze for a second preset time. The frozen initial electrode is thawed to complete the cyclic freezing process.

7. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 1, characterized in that, The thickness of the initial electrode is 200um to 600um.

8. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 6, characterized in that, The first preset time is 30 min to 1440 min.

9. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 6, characterized in that, The second preset time is 10 min to 120 min.

10. The electrode preparation method for promoting efficient ion transport in thick electrodes according to claim 1, characterized in that, The number of cyclic freezing treatments is 5 to 20 times.

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