Pole piece, battery and pole piece preparation process
By adding dual-conductivity additives to the active layer of the electrode, the problem of increased electrolyte viscosity in lithium-ion batteries at low temperatures was solved, improving lithium-ion and electron conduction capabilities and enhancing battery performance and lifespan at low temperatures.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BATTEROTECH CO LTD
- Filing Date
- 2026-03-17
- Publication Date
- 2026-05-12
AI Technical Summary
In low-temperature environments, the electrolyte viscosity of lithium-ion batteries increases, the lithium-ion migration rate decreases, leading to increased internal resistance, rapid capacity decay, and uneven lithium-ion deposition, which affects battery safety and performance.
Adding dual-conductivity additives, including lithium-containing compounds and electronically conductive materials, to the active layer of the electrode improves lithium-ion and electronic conductivity and reduces interfacial film and charge transfer resistance by setting porous lithium-containing compounds in the substrate layer and electronically conductive materials in the coating layer.
It significantly reduces the overall impedance of the electrode and battery, enhances the lithium-ion and electron conduction capacity under low-temperature conditions, slows down the battery capacity decay rate, and improves the battery performance and cycle life at low temperatures.
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Figure CN122025546A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of lithium-ion battery technology, specifically to an electrode, a battery, and an electrode preparation process. Background Technology
[0002] As lithium-ion batteries are used more and more widely, different performance requirements are being put forward for lithium-ion batteries in different usage environments.
[0003] When lithium-ion batteries are used in low-temperature environments, the low temperature increases the viscosity of the electrolyte and decreases its conductivity, leading to increased impedance and a slower migration rate of lithium ions in the active material. This makes lithium ion insertion / extraction difficult, resulting in increased internal resistance and rapid capacity decay. Furthermore, the reduced lithium ion insertion / extraction rate can also cause uneven deposition of lithium ions on the electrodes, leading to lithium plating on the electrode surface. This not only reduces battery safety but also severely impacts battery performance and lifespan.
[0004] In existing technologies, improvements to address the aforementioned problems typically involve increasing electrolyte conductivity, enhancing the kinetic properties of active materials, or reducing impedance. Increasing the low-temperature conductivity of the electrolyte impacts the cycle life and rate capability of lithium-ion batteries. Improving the kinetic properties of active materials involves optimizing the materials themselves, which is not only complex but also has limited applicability. Reducing impedance can be achieved by adding conductive materials during electrode fabrication to increase either lithium-ion or electronic conductivity. However, this approach also suffers from the limitation of focusing on only one function and failing to simultaneously improve both lithium-ion and electronic conductivity.
[0005] Therefore, there is an urgent need to provide a lithium-ion battery that can solve the above problems, improve battery performance in low-temperature environments, slow down the capacity decay rate of batteries in low-temperature environments, and increase the battery's rate capability and cycle life. Summary of the Invention
[0006] The purpose of this application is to provide an electrode, a battery, and an electrode preparation process that can solve the above problems, improve the performance of the battery in low-temperature environments, slow down the capacity decay rate of the battery in low-temperature environments, and improve the rate capability and cycle life of the battery.
[0007] To achieve the above objectives, in a first aspect, this application provides an electrode. The electrode includes a current collector and an active layer. The current collector is used for charge collection and conduction. The active layer includes a dual-conductivity additive, which comprises a substrate layer and a coating layer, wherein the substrate layer is configured as a lithium-containing compound, and the coating layer is configured as an electronically conductive material.
[0008] Based on the embodiments described above, when the battery is applied in a low-temperature environment, the low temperature environment affects the battery performance in two ways. First, the low temperature increases the viscosity of the electrolyte, which in turn reduces the migration rate of lithium ions and increases the internal resistance of the battery. Second, in the positive and negative electrode materials, the decrease in temperature slows down the diffusion rate of lithium ions, and at the same time, the impedance at the electrode / electrolyte interface increases, making it more difficult for lithium ions to cross the interface.
[0009] Through the above-described configuration of this application, a dual-conductivity additive is added to the active layer of the electrode, specifically comprising a lithium-containing compound as the substrate layer and an electronically conductive material as the coating layer. The lithium-containing compound possesses good lithium-ion conductivity, while the electronically conductive material possesses good electronic conductivity. The combination of these two additives yields a dual-conductivity additive that simultaneously possesses good lithium-ion conductivity and electronic conductivity. By adding this dual-conductivity additive to the active layer of the electrode, both the electronic conductivity and lithium-ion conductivity of the electrode are improved, effectively reducing interfacial film impedance and charge transfer impedance, enhancing lithium-ion and electron conduction capabilities under low-temperature conditions, thereby improving the battery performance in low-temperature environments.
[0010] In summary, this application improves both the electronic conductivity and lithium-ion conductivity of the electrode by adding a dual-conductivity additive to the active layer of the electrode, effectively reducing the interfacial film impedance and charge transfer impedance, enhancing the lithium-ion and electron conduction capabilities under low-temperature conditions, thereby improving the performance of the electrode and the battery as a whole in low-temperature environments, slowing down the capacity decay rate of the battery in low-temperature environments, and increasing the battery's rate capability and cycle life.
[0011] In some embodiments, the lithium-containing compound is configured as porous lithium aluminate.
[0012] Based on the above embodiments of this application, a specific material that can be selected from lithium-containing compounds is disclosed. The high specific surface area resulting from the porous nature of the compound enhances the electrolyte absorption and retention capacity of the electrode active layer. Simultaneously, the excellent lithium-ion conductivity of lithium aluminate is utilized to improve the overall lithium-ion conductivity of the active layer, thereby reducing impedance and improving the low-temperature performance of the electrode and the battery as a whole.
[0013] In some embodiments, the electronically conductive material is any one of carbon nanotubes, porous graphene, and conductive carbon black.
[0014] Based on the embodiments described above, specific materials that can be selected for electronic conductivity are disclosed. The excellent electronic conductivity of carbon nanotubes, porous graphene, and conductive carbon black is utilized to improve the overall electronic conductivity of the active layer, thereby reducing impedance.
[0015] In some embodiments, the mass ratio of the lithium compound to the electronically conductive material is 200:1.
[0016] Based on the embodiments described above in this application, the specific mass ratio of the lithium-containing compound and the electronically conductive material is limited. Excessive addition leads to a dense distribution of the electronically conductive material on the surface of the lithium-containing compound, blocking pores; insufficient addition reduces the electronic conductivity of the additive. Therefore, a dual-conductivity additive material is prepared by controlling the amount of electronically conductive material used.
[0017] In some embodiments, the active layer further includes an active substance, a binder, and a dispersant.
[0018] Based on the above embodiments of this application, other components of the active layer are disclosed, wherein the active material can be specifically selected according to the type of electrode, and the binder and dispersant can also be selected with reference to the prior art.
[0019] In some embodiments, the electrode is a positive electrode or a negative electrode.
[0020] Based on the embodiments described above, this application improves the low-temperature performance of the electrode by adding a dual-conductivity additive to the active layer of the electrode, thereby enhancing both the electronic conductivity and lithium-ion conductivity of the electrode and reducing impedance. In specific applications, this configuration can be applied to both positive and negative electrode electrodes.
[0021] According to a second aspect of this application, a battery is provided, the battery including a housing and the aforementioned electrode sheets, the electrode sheets being processed to form a wound core structure, the wound core structure being disposed within the housing.
[0022] Based on the above embodiments of this application, the battery provided by this application includes the above-mentioned electrode. Through the above configuration, by adding a dual conductivity additive to the active layer of the electrode, the electronic conductivity and lithium-ion conductivity of the electrode are improved simultaneously, effectively reducing the interface film impedance and charge transfer impedance, enhancing the lithium-ion and electron conduction capabilities under low-temperature conditions, thereby improving the performance of the electrode and the battery as a whole in low-temperature environments, slowing down the capacity decay rate of the battery in low-temperature environments, and improving the rate capability and cycle life of the battery.
[0023] According to a third aspect of this application, an electrode preparation process is provided, which is applicable to the preparation of the aforementioned electrode. The electrode preparation process includes the following steps: The lithium-containing compound was prepared by dissolving lithium nitrate in deionized water, adding porous alumina and stirring, then allowing the material to stand and freeze, and finally sintering the frozen material to obtain porous lithium aluminate.
[0024] The dual-conductivity additive was prepared by mixing porous lithium aluminate and carbon nanotubes at a mass ratio of 200:1 and stirring. After standing, the supernatant was removed and the sample was washed. The washed sample was dispersed in a solution and then freeze-dried to obtain a dual-conductivity additive of porous lithium aluminate coated with carbon nanotubes.
[0025] Electrode preparation involves mixing dual-conductivity additives, active materials, binders, and dispersants in a specific ratio to obtain an active slurry. The active slurry is then coated onto a current collector to form an active layer, followed by rolling, slitting, and die-cutting to obtain the electrode.
[0026] Based on the embodiments described above, during electrode preparation, porous alumina is used as a base. Lithium nitrate is impregnated into the pores of the porous alumina through vacuum impregnation. Subsequently, sintering is performed, causing the lithium nitrate to decompose into components such as lithium oxide at high temperature. The lithium oxide reacts with the alumina to form lithium aluminate. The porous characteristic is maintained while generating the desired product.
[0027] In some embodiments, porous alumina is prepared by the following steps: boehmite is added to a solution to obtain a hydrated alumina solution; chitin and Prönkel 123 are then added to isopropanol at a weight ratio of 4:1 and stirred to dissolve; urea is then added and stirred to obtain an intermediate solution; the hydrated alumina solution is added to the intermediate solution and heated to react; the product is then cooled to room temperature; the supernatant is removed, and the product is washed and dried; finally, it is calcined at 700°C to obtain porous alumina.
[0028] Based on the above embodiments of this application, porous alumina is first prepared by a composite template hydrothermal method using boehmite as raw material. In subsequent steps, porous lithium-containing compounds are prepared using porous alumina as raw material, and the porous characteristics are used to improve the liquid absorption and retention capacity of the prepared porous lithium-containing compounds.
[0029] In some embodiments, in the preparation step of the dual conductivity additive, before mixing porous lithium aluminate and carbon nanotubes, it is necessary to mix carbon nanotubes with a dispersant and place them in deionized water to obtain a carbon nanotube dispersion, and then mix the carbon nanotube dispersion with porous lithium aluminate.
[0030] Based on the above embodiments of this application, since carbon nanotubes are prone to agglomeration, the dispersion effect of carbon nanotubes is improved by adding a dispersant before mixing with lithium aluminate, thereby enabling carbon nanotubes to be better mixed with lithium aluminate and improving the performance of the dual conductivity additive.
[0031] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description
[0032] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the following detailed description to explain the present application, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the electrode provided in the embodiment of this application.
[0033] Figure 2 This is a schematic flowchart of the electrode preparation process provided in the embodiments of this application.
[0034] Figure 3 This is a graph showing the electrochemical impedance spectroscopy test results of the battery provided in the embodiments of this application.
[0035] Figure 4 This is a graph showing the low-temperature performance test results of the battery provided in the embodiments of this application.
[0036] Explanation of reference numerals in the attached figures 1. Current collector; 2. Active layer. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0039] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0040] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0041] In the description of this application, it should be noted that, unless otherwise stated, the terms "inner," "outer," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0042] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0043] When lithium-ion batteries are used in low-temperature environments, the low temperature increases the viscosity of the electrolyte and decreases its conductivity, leading to increased impedance and a reduced migration rate of lithium ions in the active material. This makes lithium ion insertion / extraction difficult, resulting in increased internal resistance and rapid capacity decay. Furthermore, the reduced lithium ion insertion / extraction rate can also cause uneven deposition of lithium ions on the electrodes, leading to lithium plating on the electrode surface. This not only reduces battery safety but also severely impacts battery performance and lifespan.
[0044] In existing technologies, improvements to address the aforementioned problems typically involve increasing electrolyte conductivity, enhancing the kinetic properties of active materials, or reducing impedance. Increasing the low-temperature conductivity of the electrolyte impacts the cycle life and rate capability of lithium-ion batteries. Improving the kinetic properties of active materials involves optimizing the materials themselves, which is not only complex but also has limited applicability. Reducing impedance can be achieved by adding conductive materials during electrode fabrication to increase either lithium-ion or electronic conductivity. However, this approach also suffers from the limitation of focusing on only one function and failing to simultaneously improve both lithium-ion and electronic conductivity.
[0045] Therefore, there is an urgent need to provide a lithium-ion battery that can solve the above problems, improve battery performance in low-temperature environments, slow down the capacity decay rate of batteries in low-temperature environments, and increase the battery's rate capability and cycle life.
[0046] To address the aforementioned problems in the prior art, embodiments of this application provide an electrode sheet. (Reference) Figure 1As shown, the electrode includes a current collector 1 and an active layer 2. The current collector 1 is used for charge collection and conduction. The active layer 2 includes a dual-conductivity additive, which comprises a substrate layer and a coating layer, wherein the substrate layer is configured as a lithium-containing compound and the coating layer is configured as an electronically conductive material.
[0047] It should be noted that the electronically conductive materials mentioned above in this application refer to materials with good electronic conductivity. Furthermore, it is understood that since these electronically conductive materials need to be added as additives to the active layer 2 of the electrode, their specific selection range should be further limited to materials that can be used in the battery active layer 2. The selection can be made according to the specific composition requirements of the battery active layer 2, and this application does not impose specific restrictions in this regard. Similarly, the selection range of lithium-containing compounds should also be further limited to materials that can be applied to the battery active layer 2, and the selection can be made according to the actual situation, and this application does not impose specific restrictions in this regard.
[0048] Based on the embodiments described above, when the battery is applied in a low-temperature environment, the low temperature environment affects the battery performance in two ways. First, the low temperature increases the viscosity of the electrolyte, which in turn reduces the migration rate of lithium ions and increases the internal resistance of the battery. Second, in the positive and negative electrode materials, the decrease in temperature slows down the diffusion rate of lithium ions, and at the same time, the impedance at the electrode / electrolyte interface increases, making it more difficult for lithium ions to cross the interface.
[0049] Through the above-described configuration of this application, a dual-conductivity additive is added to the active layer 2 of the electrode, specifically comprising a lithium-containing compound as the substrate layer and an electronically conductive material as the coating layer. The lithium-containing compound possesses good lithium-ion conductivity, and its porous structure further increases the specific surface area, thereby enhancing its electrolyte absorption and retention capabilities. The electronically conductive material possesses good electronic conductivity. The combination of these two additives results in a dual-conductivity additive that simultaneously exhibits good lithium-ion conductivity and electronic conductivity. By adding this dual-conductivity additive to the active layer 2 of the electrode, both the electronic conductivity and lithium-ion conductivity of the electrode are improved, effectively reducing interfacial film impedance and charge transfer impedance, enhancing lithium-ion and electron conduction capabilities under low-temperature conditions, and thus improving the battery performance in low-temperature environments.
[0050] In summary, this application improves both the electronic conductivity and lithium-ion conductivity of the electrode by adding a dual-conductivity additive to the active layer 2 of the electrode, effectively reducing the interfacial film impedance and charge transfer impedance, enhancing the lithium-ion and electron conduction capabilities under low-temperature conditions, thereby improving the performance of the electrode and the battery as a whole under low-temperature conditions, slowing down the capacity decay rate of the battery under low-temperature conditions, and increasing the rate capability and cycle life of the battery.
[0051] Furthermore, in some embodiments of this application, the lithium-containing compound can be further configured as a porous lithium-containing compound to further restrict the microstructure of the lithium-containing compound. By configuring it as a porous structure, the specific surface area of the lithium-containing compound is increased, thereby improving the liquid absorption and retention capacity of the electrolyte, and thus improving the overall liquid absorption and retention capacity of the electrode active layer 2 for the electrolyte, so as to further help reduce impedance.
[0052] Furthermore, in some embodiments of this application, the electrode can be a positive electrode or a negative electrode.
[0053] Based on the embodiments described above, this application improves the low-temperature performance of the electrode by adding a dual-conductivity additive to the active layer 2 of the electrode, thereby enhancing both the electronic conductivity and lithium-ion conductivity of the electrode and reducing impedance. In specific applications, this setting can be applied to both positive and negative electrode electrodes.
[0054] Furthermore, in some embodiments of this application, the active layer 2 may also include an active substance, a binder, and a dispersant.
[0055] Based on the above embodiments of this application, other components of the active layer 2 are disclosed, wherein the active material can be specifically selected according to the type of electrode, and the binder and dispersant can also be selected with reference to the prior art.
[0056] Specifically, when this dual-conductivity additive is applied to the positive electrode sheet, the current collector 1 of the positive electrode sheet can be made of materials such as aluminum foil, the positive electrode active material can be lithium iron phosphate, and the binder can be any one or more of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), and sodium alginate (SA). The dispersant can be any one or more of carboxymethyl cellulose (CMC), sodium polyacrylate (PAAS), polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), and polyethylene glycol (PEG). The dual-conductivity additive is then mixed with the above-mentioned active material, binder, and dispersant to prepare a slurry, which is subsequently coated onto the current collector 1 to form the active layer 2. Similarly, when the dual-conductivity additive is applied to the negative electrode, the current collector 1 can be made of materials such as copper foil, the active material can be made of materials such as graphite, and the binder and dispersant can be selected with reference to the positive electrode. The specific settings can be made according to the actual situation, and this application does not impose specific restrictions on them.
[0057] In this application, within the aforementioned limitations, the lithium-containing compound can be selected from any suitable material. In one exemplary embodiment of this application, the lithium-containing compound can be configured as porous lithium aluminate.
[0058] Based on the above embodiments of this application, a specific material that can be selected from lithium-containing compounds is disclosed. The high specific surface area resulting from the porous nature of the active layer 2 is utilized to improve its ability to absorb and retain electrolyte. Simultaneously, the excellent lithium-ion conductivity of lithium aluminate is utilized to improve the overall lithium-ion conductivity of the active layer 2, thereby reducing impedance and improving the low-temperature performance of the electrode and the battery as a whole.
[0059] Similarly, in this application, within the aforementioned limitations, the electronically conductive material can be any suitable material. In one exemplary embodiment of this application, the electronically conductive material can be any one of carbon nanotubes, porous graphene, and conductive carbon black.
[0060] Based on the embodiments described above, specific materials that can be selected for electronic conductivity are disclosed. The good electronic conductivity of carbon nanotubes, porous graphene, and conductive carbon black is utilized to improve the overall electronic conductivity of the active layer 2, thereby reducing impedance.
[0061] In some embodiments of this application, the mass ratio of lithium-containing compound to electronically conductive material is 200:1.
[0062] Based on the embodiments described above in this application, the specific mass ratio of the lithium-containing compound and the electronically conductive material is limited. Excessive addition will cause the electronically conductive material to be densely distributed on the surface of the lithium-containing compound, blocking pores; insufficient addition will reduce the electronic conductivity of the additive.
[0063] Based on the above technical solutions, this application embodiment also provides a battery, which includes a casing and the aforementioned electrode sheets, wherein the electrode sheets are processed to form a core structure, and the core structure is disposed inside the casing.
[0064] Based on the above embodiments of this application, the battery provided by this application includes the above-mentioned electrode. Through the above configuration, by adding a dual conductivity additive to the active layer 2 of the electrode, the electronic conductivity and lithium-ion conductivity of the electrode are improved simultaneously, effectively reducing the interface film impedance and charge transfer impedance, enhancing the lithium-ion and electron conduction capabilities under low temperature conditions, thereby improving the performance of the electrode and the battery as a whole in low temperature environments, slowing down the capacity decay rate of the battery in low temperature environments, and improving the rate capability and cycle life of the battery.
[0065] Based on the above technical solutions, this application also provides an electrode preparation process, referring to... Figure 2 As shown, this electrode preparation process is applicable to the preparation of the aforementioned electrodes. The electrode preparation process includes the following steps: To prepare S002 lithium-containing compounds, lithium nitrate was dissolved in deionized water, porous alumina was added and stirred, then placed in a vacuum environment and allowed to stand. The material was then frozen for 24 hours and sintered at 600°C for 5 hours to obtain porous lithium aluminate.
[0066] The S003 dual conductivity additive was prepared by mixing porous lithium aluminate and carbon nanotubes at a mass ratio of 200:1 and stirring. After standing for 15 hours, the supernatant was removed and the sample was washed. The washed sample was dispersed in a mixture of anhydrous ethanol and deionized water and then freeze-dried to obtain a carbon nanotube-coated porous lithium aluminate dual conductivity additive.
[0067] S004 electrode preparation involves mixing dual-conductivity additives, active materials, binders, and dispersants in a specific ratio to obtain an active slurry. The active slurry is then coated onto a current collector 1 to form an active layer 2, followed by rolling, slitting, and die-cutting to obtain the electrode.
[0068] Based on the above embodiments of this application, during electrode preparation, porous alumina is first prepared using boehmite as a raw material. Then, based on the porous alumina, lithium nitrate is impregnated into the pores of the porous alumina through vacuum impregnation. Subsequently, through sintering, the lithium nitrate decomposes into components such as lithium oxide at high temperature. The lithium oxide reacts with the alumina to form lithium aluminate. This process maintains the porous characteristic while generating the desired product.
[0069] In addition, further reference Figure 2 As shown in the present application, before the preparation of the lithium-containing compound in step S002, porous alumina can be prepared by the following steps: S001 Porous alumina preparation, using boehmite as raw material, deionized water is added to prepare a hydrated alumina solution, then chitin and Pluronic 123 are added to isopropanol at a weight ratio of 4:1 and stirred to dissolve, then urea is added and stirred until completely dissolved to obtain an intermediate solution, then the hydrated alumina solution is added to the intermediate solution and reacted at 140°C, then the product is rapidly cooled to room temperature by water bath, the supernatant is removed and then washed and dried, and finally calcined at 700°C for 2 hours to obtain porous alumina.
[0070] Furthermore, in some embodiments of this application, in the lithium compound preparation step, before the material is sintered, the material is placed in a vacuum freeze-drying oven and freeze-dried for 40 hours at an environment below -50°C.
[0071] Based on the above embodiments of this application, water in the solution is removed by freeze drying. At the same time, the low-temperature freezing method can reduce the impact of the water removal process on the porous structure, thereby better ensuring the porous structure of the product. As a result, when the final porous lithium aluminate is applied to the active layer 2 of the electrode, it can improve the liquid absorption and retention capacity of the electrolyte.
[0072] In some embodiments, in the preparation step of the dual conductivity additive, before mixing porous lithium aluminate and carbon nanotubes, it is necessary to mix carbon nanotubes with a dispersant and place them in deionized water to obtain a carbon nanotube dispersion, and then mix the carbon nanotube dispersion with porous lithium aluminate.
[0073] Based on the above embodiments of this application, since carbon nanotubes are prone to agglomeration, the dispersion effect of carbon nanotubes is improved by adding a dispersant before mixing with lithium aluminate, thereby enabling carbon nanotubes to be uniformly mixed with lithium aluminate and improving the performance of the dual conductivity additive.
[0074] The performance of the electrode prepared by the electrode manufacturing process in this application will be further compared and illustrated below through a specific embodiment and a comparative example.
[0075] Example 1 This embodiment uses the electrode preparation process disclosed in this application to prepare a negative electrode sheet, and then performs performance testing on the negative electrode sheet, specifically including: (1) Preparation of porous alumina: 6.6 g of boehmite was added to deionized water to prepare a hydrated alumina solution with a concentration of 0.6 mol / L. Chitin and Prönkel 123 were then added to 40 ml of isopropanol at a weight ratio of 4:1 and stirred until dissolved. 2.4 g of urea was then added and stirred until completely dissolved to obtain an intermediate solution. 30 ml of the hydrated alumina solution was then added to the intermediate solution, and the mixture was stirred for 30 minutes. The solution was then transferred to a reaction vessel and reacted at 140 °C for 3 hours. The product was then rapidly cooled to room temperature using a water bath. After removing the supernatant, the product was washed 3-5 times with deionized water and anhydrous ethanol. It was then vacuum dried at 80 °C for 15 hours and finally calcined at 700 °C for 2 hours to obtain porous alumina.
[0076] (2) Preparation of lithium-containing compounds: 5g of lithium nitrate was dissolved in 30ml of deionized water, and 3g of porous alumina was added and stirred for 30 minutes. The mixture was then placed in a vacuum environment and allowed to stand for 6 hours to allow the lithium nitrate to penetrate the pores of the porous alumina. The material was then frozen for 24 hours. The frozen-solidified material was placed in a vacuum freeze-drying oven and freeze-dried for 40 hours at below -50°C and an ambient pressure less than 6 MPa to remove moisture from the lithium nitrate solution. Finally, the freeze-dried material was sintered at 600°C for 5 hours to obtain porous lithium aluminate.
[0077] (3) Preparation of dual-conductivity additives Sodium dodecylbenzenesulfonate was used as a dispersant. Sodium dodecylbenzenesulfonate and carbon nanotubes were weighed at a mass ratio of 4:1 and then added together to deionized water. The mixture was ultrasonically dispersed for 1 hour to obtain a carbon nanotube dispersion with a concentration of 0.5 g / L. Porous lithium aluminate was then added to the carbon nanotube dispersion. The porous lithium aluminate and carbon nanotubes were mixed at a mass ratio of 200:1 and stirred for 4 hours until homogeneous. After standing for 15 hours, the supernatant was removed, and the lower solid material was washed 3-5 times with deionized water and anhydrous ethanol. Finally, the washed material was dispersed in a mixture of anhydrous ethanol and deionized water at a ratio of 2:1 and freeze-dried to obtain a carbon nanotube-coated porous lithium aluminate dual-conductivity additive.
[0078] (4) Electrode preparation Graphite as the active material, sodium carboxymethyl cellulose as the dispersant, styrene-butadiene rubber as the binder, conductive carbon black as the conductive agent, and the aforementioned dual-conductivity additives were mixed in a mass ratio of 97:0.8:1.5:0.5:0.2, using deionized water as the solvent, and stirred to prepare the negative electrode slurry. Subsequently, the negative electrode slurry was prepared at a concentration of 9.08 mg / cm³. 2 The areal density of the electrode was coated onto a current collector 1 made of copper foil with a thickness of 6 μm to obtain an electrode structure. After drying in an oven, the electrode was then processed at a density of 1.65 g / cm³. 3 The compaction density is applied to the electrode structure by rolling, and finally the negative electrode is obtained through slitting and die-cutting processes.
[0079] (5) Performance testing The prepared negative electrode and positive electrode were assembled to prepare a single-layer soft-pack battery, and electrochemical impedance spectroscopy (EIS) and low-temperature performance tests were performed.
[0080] Comparative Example In the comparative example, a single-layer pouch cell was selected for electrochemical impedance spectroscopy and low-temperature performance testing. The difference between this single-layer pouch cell and Example 1 is that the active layer 2 of the electrode did not contain a dual-conductivity additive.
[0081] refer to Figure 3 and Figure 4 As shown, in which, Figure 3 The Nyquist plots are obtained from electrochemical impedance spectroscopy measurements of Example 1 and the comparative example, respectively, with the battery state of charge at 50%. Figure 4 This is a comparison chart of the low-temperature performance of batteries measured at a discharge rate of 0.33C and a voltage range of 2.5V to 3.65V.
[0082] Specifically, refer to Figure 3 As shown in the figure, the horizontal axis represents the real part of the impedance Z', and the vertical axis represents the negative value of the imaginary part of the impedance -Z''. It can be seen from the figure that the impedance measured in Example 1 of this application is significantly less than the impedance of the comparative example. Therefore, by adding a dual-conductivity additive to the electrode, the impedance of the electrode and the battery as a whole can be significantly reduced.
[0083] refer to Figure 4As can be seen, the initial test temperature was 25°C, and initially, the battery capacity retention rate of both Example 1 and the comparative example was 100%. Subsequently, when the ambient temperature dropped to 0°C, the battery capacity retention rate of Example 1 was approximately 80%, while that of the comparative example was approximately 75%. When the ambient temperature dropped to -10°C, the battery capacity retention rate of Example 1 was approximately 60%, while that of the comparative example was approximately 45%. When the ambient temperature dropped to -20°C, the battery capacity retention rate of Example 1 was approximately 40%, while that of the comparative example was approximately 25%. It is evident that by adding a dual-conductivity additive to the electrode, the battery capacity retention rate at low temperatures can be significantly improved, and the battery capacity decay rate can be slowed down.
[0084] In summary, as can be seen from the above, adding dual-conductivity additives to the electrode can significantly reduce the impedance of the electrode and the battery as a whole, enhance the conduction ability of lithium ions and electrons at low temperatures, improve the problem of lithium ion deposition and lithium plating, and at the same time, improve the battery's capacity retention rate at low temperatures, slow down the battery's capacity decay rate, and effectively improve the battery's performance and lifespan at low temperatures.
[0085] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.
[0086] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.
[0087] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.
Claims
1. An electrode sheet, characterized in that, The electrode includes: Current collectors are used for charge collection and conduction. An active layer comprising a dual-conductivity additive, the dual-conductivity additive comprising a matrix layer and a coating layer, wherein the matrix layer is configured as a lithium-containing compound and the coating layer is configured as an electronically conductive material.
2. The electrode sheet according to claim 1, characterized in that, The lithium-containing compound is configured as porous lithium aluminate.
3. The electrode sheet according to claim 1, characterized in that, The electronically conductive material is selected from any one of carbon nanotubes, porous graphene, and conductive carbon black.
4. The electrode sheet according to any one of claims 1-3, characterized in that, The mass ratio of the lithium-containing compound to the electronically conductive material is 200:
1.
5. The electrode sheet according to any one of claims 1-3, characterized in that, The active layer also includes active substances, binders, and dispersants.
6. The electrode sheet according to any one of claims 1-3, characterized in that, The electrode is either a positive electrode or a negative electrode.
7. A battery, characterized in that, The battery includes: The shell; and, The electrode sheet according to any one of claims 1-6, wherein the electrode sheet is processed to form a core structure, and the core structure is disposed within the housing.
8. An electrode preparation process, applicable to the preparation of electrodes as described in any one of claims 2-6, characterized in that, The electrode preparation process includes the following steps: The lithium-containing compound was prepared by dissolving lithium nitrate in deionized water, adding porous alumina and stirring, then allowing the material to stand and freeze, and sintering the frozen material to obtain porous lithium aluminate. Preparation of dual conductivity additive: porous lithium aluminate and carbon nanotubes were mixed and stirred at a mass ratio of 200:
1. After standing, the supernatant was removed and the sample was washed. The washed sample was dispersed in a solution and then freeze-dried to obtain a dual conductivity additive of porous lithium aluminate coated with carbon nanotubes. Electrode preparation involves mixing dual-conductivity additives, active materials, binders, and dispersants in a specific ratio to obtain an active slurry. The active slurry is then coated onto a current collector to form an active layer, followed by rolling, slitting, and die-cutting to obtain the electrode.
9. The electrode preparation process according to claim 8, characterized in that, The porous alumina is prepared by the following steps: boehmite is added to a solution to obtain a hydrated alumina solution; chitin and Prönkel 123 are then added to isopropanol at a weight ratio of 4:1 and stirred to dissolve; urea is then added and stirred to obtain an intermediate solution; the hydrated alumina solution is added to the intermediate solution and heated to react; the product is then cooled to room temperature; the supernatant is removed, and the product is washed and dried; finally, it is calcined at 700°C to obtain porous alumina.
10. The electrode preparation process according to claim 8, characterized in that, In the preparation step of the dual conductivity additive, before mixing porous lithium aluminate and carbon nanotubes, the carbon nanotubes need to be mixed with a dispersant and placed in deionized water to obtain a carbon nanotube dispersion, and then the carbon nanotube dispersion is mixed with porous lithium aluminate.