Energy storage battery cell and preparation method thereof

Abstract

The embodiments of the present application relate to the field of energy storage and provide an energy storage battery cell and a preparation method thereof, the preparation method comprising: providing a current collector; uniformly dispersing a ceramic material and an adhesive by shearing with a high-speed airflow to obtain a mixed powder, wherein the mass percentage of the ceramic material is 80wt% to 98wt%, and the mass percentage of the adhesive is 2wt% to 20wt%; roller-pressing the mixed powder to obtain a ceramic diaphragm, wherein the ceramic diaphragm is located at least at the pole ear portion and the junction between the pole ear portion and the active material portion; forming an active material layer, wherein a first preset range is provided between the active material layer and the ceramic diaphragm; performing a heat curing treatment, wherein a second preset range is provided between the active material layer after the heat curing treatment and the ceramic diaphragm; the heat curing treatment comprising: roller-pressing the current collector comprising the ceramic diaphragm and the active material layer at a preset temperature so that the ceramic diaphragm is fixed to the current collector and the active material layer is fixed to the current collector.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of energy storage, and in particular to an energy storage battery cell and a method for preparing the same. Background Art

[0002] In recent years, lithium-ion batteries have attracted great attention due to their excellent characteristics such as high energy density, high output voltage, low self-discharge rate, long service life, no memory effect and environmental friendliness. They have developed by leaps and bounds, their market share has continued to expand, and they have occupied a dominant position.

[0003] At present, single lithium batteries are mainly cylindrical, square and soft-pack. The methods adopted in the battery production process are mainly stacking and winding. The stacking method is generally die-cut and then cut and stacked. It has low production efficiency, low consistency accuracy, and low rate and cycle performance. The winding method has higher production efficiency. Generally, battery cells without die-cutting process adopt the post-process welding of pole ears for drainage. In this process, the problem of pole ear alignment needs to be considered.

[0004] Among them, square batteries are mostly single-pole and multi-pole processes. The single-pole process is to connect the pole tabs to the pole sheet by ultrasonic welding before winding, and then wind it into a battery through the welded pole tab drainage; the multi-pole process is to die-cut the pole sheet. After die-cutting, it can be divided into two types: one is to stack the pieces after cutting, and the other is to directly wind. Both methods ultimately use the pole end as the pole tab for multi-pole super welding as the drainage terminal. Because the subsequent welding process requires the pole tab to be welded separately on the pole sheet, the pole tab is very easy to tear during this process, and there is no effective full inspection and interception measures. After leakage, it will cause safety risks to the battery cell and poor voltage difference between the battery cells in the module. Summary of the Invention

[0005] The embodiments of the present application provide an energy storage battery cell and a method for preparing the same, which are at least beneficial for improving the mechanical strength of the tab.

[0006] According to some embodiments of the present application, on the one hand, an embodiment of the present application provides a method for preparing an energy storage battery cell, comprising: forming a diaphragm and a positive electrode sheet and a negative electrode sheet located on both sides of the diaphragm; the process steps for forming the positive electrode sheet include: providing a current collector, the current collector having two pole ear portions and an active material portion located between the two pole ear portions; forming a ceramic diaphragm, the ceramic diaphragm being located at least at the pole ear portion and the junction between the pole ear portion and the active material portion, and the process steps for forming the ceramic diaphragm include: uniformly dispersing a ceramic material and an adhesive by high-speed airflow shearing to obtain a mixed powder, wherein the mass percentage of the ceramic material is 80wt%~98wt%, and the mass percentage of the adhesive is 2wt%~20wt%; rolling the mixed powder to obtain the ceramic diaphragm; forming an active material layer, wherein the active material layer is located on the active material portion; wherein a first preset range is provided between the active material layer and the ceramic diaphragm; performing a heat curing treatment, wherein a second preset range is provided between the active material layer and the ceramic diaphragm after the heat curing treatment; the heat curing treatment comprises: performing a roller pressing treatment on the current collector comprising the ceramic diaphragm and the active material layer at a preset temperature so that the ceramic diaphragm is fixed to the current collector and the active material layer is fixed on the current collector; performing a die-cutting on the current collector corresponding to the pole ear portion according to preset parameters so that the pole ear portion of the current collector forms a pole ear; cutting the current collector to form two identical positive electrode sheets; performing a winding treatment on the diaphragm, the positive electrode sheet and the negative electrode sheet.

[0007] In some embodiments, the second preset range is 0.5 mm to 1.5 mm.

[0008] In some embodiments, the adhesive is one or more of polytetrafluoroethylene, polyhexafluoropropylene, or polyvinylidene fluoride.

[0009] In some embodiments, the adhesive is a polytetrafluoroethylene material, the mass percentage of the ceramic material is 85wt%~95wt%, and the mass percentage of the polytetrafluoroethylene material is 5wt%~15wt%.

[0010] In some embodiments, the process parameters for uniformly dispersing the ceramic material and the adhesive by high-speed airflow shearing to obtain a mixed powder include: a feed flow rate of 100L / h~2000L / h, an air flow velocity of 10m / s~500m / s, and a temperature of 20℃~60℃.

[0011] In some embodiments, the preset temperature is 60-130°C.

[0012] In some embodiments, the process steps for forming the active material layer include: uniformly dispersing the conductive agent, the active material and the adhesive by high-speed airflow shearing to obtain a conductive powder, wherein the mass percentage of the conductive agent is 1wt% to 2wt%, the mass percentage of the active material is 95wt% to 97wt%, and the mass percentage of the adhesive is 1wt% to 4wt%; and rolling the conductive powder to obtain the active material layer.

[0013] In some embodiments, the process steps of performing the thermal curing treatment and the die-cutting include: die-cutting the current collector corresponding to the pole ear portion according to preset parameters so that the end of the current collector forms a pole ear; the ceramic diaphragm is located at the pole ear and at the junction between the pole ear and the active material portion; and performing the thermal curing treatment on the current collector.

[0014] According to some embodiments of the present application, on the other hand, the embodiments of the present application further provide an energy storage battery cell, comprising: a diaphragm, and a positive electrode sheet and a negative electrode sheet located on both sides of the diaphragm, the positive electrode sheet being prepared by the preparation method of the energy storage battery cell described in any of the above embodiments; the positive electrode sheet comprising a current collector, a ceramic diaphragm and an active material layer, the current collector having a pole ear and an active material portion, the ceramic diaphragm being located at least on the pole ear and at the junction between the pole ear and the active material portion; the active material layer being located on the active material portion, and a second preset range being present between the active material layer and the ceramic diaphragm.

[0015] In some embodiments, the ceramic diaphragm is also located on part of the active material portion, and the distance of the ceramic diaphragm located in the active material portion along the first direction is a third preset range, and the ratio of the third preset range to the second preset range is 5~20.

[0016] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0017] The energy storage cell preparation method provided in the embodiments of the present application uses high-speed airflow shearing to uniformly mix the ceramic material and binder, rather than using an NMP (N-Methylpyrrolidone) solution to dissolve the binder and disperse the ceramic material. This avoids the safety concerns of NMP solvent volatilization. Compared to using an NMP solution to prepare ceramic diaphragms, the high-speed airflow shearing method can be considered a dry process for preparing ceramic diaphragms. During this process, the high-speed shear force exerted on the binder creates friction between the binder molecules, generating fibers that can coat the ceramic material and form a network structure, resulting in excellent mechanical properties. This improves the mechanical properties of the tab and prevents tab tearing. Secondly, a thermal curing process is used to form the positive electrode sheet. Specifically, the current collector, comprising the ceramic diaphragm and active material layer, is subjected to a roll-pressing process at a predetermined temperature. This effectively increases the compaction density of the ceramic and active material layers in the positive electrode sheet, further enhancing the entanglement of the various materials within the tab and active material layer, and improving mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments are exemplified by the figures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a flow chart corresponding to a method for preparing an energy storage cell provided in one embodiment of the present application;

[0020] Figures 2 to 10 A schematic structural diagram corresponding to each step of forming a positive electrode sheet in a method for preparing an energy storage cell provided in one embodiment of the present application;

[0021] Figure 11 A top view of an energy storage cell undergoing a winding process in a method for preparing an energy storage cell provided in one embodiment of the present application. DETAILED DESCRIPTION

[0022] As can be seen from the background art, the mechanical strength of the tabs of current energy storage cells is poor and they are prone to tearing.

[0023] An embodiment of the present application provides a method for preparing an energy storage battery cell, which utilizes high-speed airflow to shear and disperse ceramic materials and adhesives, so that the mechanical strength of the ceramic diaphragm formed thereby is greater, thereby avoiding the problem of tearing of the tabs.

[0024] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0025] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0027] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0028] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0029] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0030] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) as being on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. Conversely, when describing a component as being on the surface of another component or as being formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0031] In the description of the embodiments of this application, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them) or another component can be present between them. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located between them.

[0032] The terms used in the description of the various embodiments described herein are intended only to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described herein and in the appended claims, "parts" are intended to include the plural form unless the context clearly indicates otherwise. Parts include components such as layers, films, regions, or plates. This improves the yield of the battery cell.

[0033] Figure 1 This is a flow chart corresponding to a method for preparing an energy storage cell provided in one embodiment of the present application.

[0034] According to some embodiments of the present application, the present application provides a method for preparing an energy storage battery cell. Figure 1 The preparation method includes: forming a separator; forming a positive electrode sheet; forming a negative electrode sheet; assembling the positive electrode sheet, the negative electrode sheet and the separator, wherein the positive electrode sheet and the negative electrode sheet are respectively located on both sides of the separator; and performing a winding process on them.

[0035] The process steps for forming a positive electrode sheet include: providing a current collector having two tabs and an active material portion located between the two tabs. The process steps for forming a positive electrode sheet include: forming a ceramic diaphragm, the ceramic diaphragm being located at least at the tabs and at the interface between the tabs and the active material portion. The process steps for forming the ceramic diaphragm include: uniformly dispersing a ceramic material and a binder using high-speed airflow shear to obtain a mixed powder, wherein the mass percentage of the ceramic material is 80wt% to 98wt% and the mass percentage of the binder is 2wt% to 20wt%; and roller-pressing the mixed powder to obtain a ceramic diaphragm. The process steps for forming a positive electrode sheet include: forming an active material layer, the active material layer being located on the active material portion; wherein a first preset range is defined between the active material layer and the ceramic diaphragm. The process steps for forming the positive electrode sheet include: performing a heat curing treatment, wherein a second preset range is defined between the active material layer and the ceramic diaphragm after the heat curing treatment; the heat curing treatment includes: rolling the current collector comprising the ceramic diaphragm and the active material layer at a preset temperature to secure the ceramic diaphragm to the current collector and the active material layer to the current collector. The process steps for forming the positive electrode sheet include: die-cutting the current collector corresponding to the electrode tab according to preset parameters to form the electrode tab at the electrode tab of the current collector. The process steps for forming the positive electrode sheet include: cutting the current collector to form two identical positive electrode sheets.

[0036] The preparation method of the energy storage battery provided in the embodiment of the present application is to mix the ceramic material and the adhesive evenly by shearing with a high-speed airflow, rather than using a process of dissolving the adhesive and dispersing the ceramic material with an NMP solution, which can avoid the safety problem of NMP solvent volatilization. Compared with the preparation of ceramic diaphragms using NMP solution, the high-speed airflow shearing method can be regarded as preparing ceramic diaphragms by a dry process. In this process, the adhesive forms friction between the adhesive molecules through a high-speed shearing force, thereby producing fibers. This fiber can coat the ceramic material and form a network structure, thereby having good mechanical properties, thereby improving the mechanical properties of the tab and avoiding tab tearing. Secondly, a thermal curing treatment is used to form a positive electrode sheet, that is, a current collector comprising a ceramic diaphragm and an active material layer is subjected to a roller pressing process at a preset temperature, which can effectively improve the compaction density of the ceramic and active material layers in the positive electrode sheet, and can further improve the degree of entanglement of various substances in the tab and the active material layer, thereby improving mechanical properties.

[0037] According to the appearance classification, the prepared energy storage cells can be divided into square cells, round cells or soft-pack cells. According to the capacity classification, the energy storage cells can be divided into 50Ah, 100Ah, 150Ah, 200Ah, 280Ah, 306Ah, 314Ah, 500+Ah, 800+Ah and 1000+Ah models. According to the chemical composition and working principle of the cell, the energy storage cell can be a lithium-ion battery, a lead-acid battery, a sodium-ion battery or a nickel-metal hydride battery. The embodiment of the present application takes the preparation method of a lithium-ion battery as an example. Those skilled in the art can replace the lithium ions in the positive electrode sheet, the negative electrode sheet and the electrolyte with corresponding metal ions according to actual needs. For example, in sodium-ion batteries, the lithium transition metal oxide of the subsequent positive electrode active material is replaced by any of the corresponding layered metal oxides (such as NaFeO2), polyanion compounds (NaFePO4) and Prussian blue compound systems (such as NaMnFe(CN)6-zH2O), and the electrolyte is replaced by any of the organic liquid electrolyte, solid composite electrolyte or solid electrolyte.

[0038] The following detailed description of the various embodiments of the present application is provided in conjunction with the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to facilitate a better understanding of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0039] Figures 2 to 10 This is a schematic structural diagram corresponding to each step of preparing a positive electrode sheet in a method for preparing an energy storage cell provided in one embodiment of the present application.

[0040] Figure 2 A top view corresponding to a current collector is provided in the method for preparing an energy storage cell provided in one embodiment of the present application; Figure 3 for Figure 2 Cross-sectional view along section A1-A2.

[0041] refer to Figure 2 and Figure 3 The preparation method for forming a positive electrode sheet includes: providing a current collector 10, the current collector 10 having two electrode ear portions 12 and an active material portion 11 located between the two electrode ear portions 12.

[0042] In some embodiments, the current collector 10 can be aluminum foil, which is cheaper than copper foil. A dense oxide film is formed on the surface of the aluminum foil, and the oxide film is very thin, which can improve the corrosion resistance of the aluminum foil, and electrons can achieve conductivity through the tunnel effect.

[0043] In some embodiments, the current collector 10 may also be a composite current collector comprising three stacked layers: an organic middle layer, and copper-plated and aluminum-plated upper and lower layers. The organic material may be PET (polyethylene terephthalate), PP (polypropylene), or PI (polyimide).

[0044] In some embodiments, the current collector 10 can also be a carbon-based current collector, that is, there is a conductive carbon layer on the aluminum foil. The conductive carbon layer can serve as a protective layer to effectively protect the current collector to prevent corrosion of the metal current collector, thereby increasing the life of the current collector; secondly, the conductive carbon layer itself has a low resistivity, so as not to produce excessive electrical losses.

[0045] The conductive carbon layer can be made of flake graphite, spherical graphite, small-sized active particles, carbon nanotubes, graphene, etc. 2 / g) compared to flake graphite (specific surface area of ​​16m 2 / g) provides a larger surface area for contact with the lithium ion particles in the subsequently formed active material layer 120, resulting in a corresponding positive electrode exhibiting superior cyclic voltammetry characteristics and improved dispersibility in the slurry. Using small or even nanoscale active particles or carbon nanotubes, graphene, or other materials as the conductive carbon layer can significantly improve the energy density and rate performance of lithium-ion batteries.

[0046] It should be noted that the carbon-based current collector can be represented by the conductive carbon layer covering both the upper and lower surfaces of the aluminum foil, or by the conductive carbon layer covering a portion of the surface of the aluminum foil. The conductive carbon layer covering a portion of the surface of the aluminum foil can include a conductive carbon layer on the aluminum foil corresponding to the active material portion 11, a conductive carbon layer on the aluminum foil corresponding to a portion of the active material portion 11, a conductive carbon layer on the aluminum foil corresponding to the active material portion 11 and a subsequent ceramic diaphragm, etc.

[0047] In addition, in other embodiments, for example, the current collector of the positive electrode sheet in a sodium ion battery may also be aluminum foil.

[0048] The active material portion 11 is a region for forming an active material layer. The active material particles in the active material layer serve as carriers for oxidation reactions in the battery cell.

[0049] The tab 12 is the area where the tab will be formed. The tab is the metal conductor that leads the positive electrode of the energy storage cell out of the battery cell. The tab is the point of contact between the positive electrode and the external contact component during charging and discharging of the battery cell. The external contact component can be a terminal.

[0050] In some embodiments, two tabs can be formed at both ends of the current collector 10, and finally cut to form two identical positive electrode sheets, thus defining two tab portions 12 at both ends of the current collector 10. In other embodiments, a current collector can be cut to form multiple positive electrode sheets, and the active material portion 11 and the tab portions can be spaced apart according to a certain size ratio, and the tab portions can be subsequently die-cut to form corresponding tabs.

[0051] In some embodiments, the boundary line and size relationship between the tab portion 12 and the active material portion 11 are not limited in the present application, and those skilled in the art can set them according to specific needs. In one example, the length of the active material portion 11 can be 55 mm, and the length of the tab portion 12 can be 3 mm.

[0052] Figure 4 This is a top view corresponding to the formation of a ceramic diaphragm 110 in the method for preparing an energy storage cell provided in one embodiment of the present application; Figure 5 for Figure 4 Cross-sectional view along section A1-A2.

[0053] refer to Figure 4 and Figure 5 The process steps for forming the positive electrode sheet include: forming a ceramic diaphragm 110 , and the ceramic diaphragm 110 is at least located at the electrode ear portion 12 and the junction between the electrode ear portion 12 and the active material portion 11 .

[0054] During the tab welding process, that is, when the tab is welded to the adapter, the tab needs to be assisted in welding by making the welding surface perpendicular to the extension direction of the positive electrode sheet. During this process, the tab deforms significantly and welding stress is present, which makes the tab prone to tearing. In the positive electrode sheet provided in the embodiment of the present application, a ceramic diaphragm 110 is formed. The ceramic diaphragm 110 is located at the tab portion 12 and at the junction of the tab portion 12 and the active material portion 11. The ceramic diaphragm 110, sheared by the high-speed airflow, has a high mechanical strength, which can enhance the mechanical strength of the tab and effectively prevent the tab from tearing during the welding process.

[0055] The process steps for forming the ceramic diaphragm 110 include: uniformly dispersing the ceramic material and the adhesive through high-speed airflow shearing to obtain a mixed powder. In this way, the adhesive is fiberized based on the shearing force of the high-speed airflow, and the fibrous adhesive is dispersed throughout the system, and a three-dimensional network structure is formed based on the adhesion between the adhesives. The three-dimensional network structure can not only construct pores, but also enhance the mechanical properties. The ceramic material can fill the pores to prevent the ceramic materials from agglomerating with each other and affecting the final insulation effect. The three-dimensional network structure enhances the mechanical properties, and the ceramic diaphragm 110 located at the junction of the ear portion 12 and the active material portion 11 subsequently has a higher mechanical strength, thereby avoiding the problem of the ear tearing during the welding process.

[0056] Secondly, high-speed airflow shearing disperses the ceramic material, and high-speed airflow is used to promote the collision between ceramic material particles. In addition, the shearing effect of the airflow on the ceramic material and the impact and shearing of the ceramic material and other components promote the crushing of the ceramic material, thereby causing the ceramic material to be broken from large particles to small particles, and from large particle size to small particle size. The average particle size of the final ceramic crushed product is smaller, the particle size distribution is narrower, and the particle surface is smooth and regular, thereby improving the compaction density of the final formed ceramic diaphragm 110.

[0057] The ceramic material and adhesive are sheared by high-speed airflow, forming the ceramic diaphragm 110 through a dry process. This process, also known as a solvent-free (SF) process, not only reduces the solvent drying step but also lowers production costs, improves production efficiency, and reduces environmental pollution. This dry process also reduces the thickness of the ceramic diaphragm 110, thereby reducing the thickness of the positive electrode layer in the battery cell, thereby increasing the energy density of the battery.

[0058] Prior to high-speed airflow shearing, the ceramic material and adhesive are pretreated until the mixture is visually free of visible agglomerates. This pretreatment involves slow stirring followed by high-temperature aging. The slow stirring speed is less than 5 m / s. High-temperature aging occurs at a temperature of 40°C to 50°C for 48 to 96 hours. This slow stirring followed by high-temperature aging allows the ceramic material and adhesive to undergo a process of opening and stretching the polymer chains, thereby preventing adverse effects such as molecular chain breakage and functional group destruction caused by high-speed shearing.

[0059] It should be noted that the main principle of high-speed airflow shearing treatment is to suck the material into the airflow through a high-speed rotating centrifuge, and under the action of high-pressure gas, it is accelerated, sheared, ground and other processes.

[0060] In some embodiments, the process parameters for uniformly dispersing the ceramic material and the binder by high-speed airflow shearing to obtain a mixed powder include: feed flow rate, airflow velocity, and temperature, wherein the feed flow rate is ≤2000 L / h, the airflow velocity is ≤500 m / s, and the temperature is 20°C to 60°C. The mixture of the ceramic material and the binder is placed in an absorption device, wherein the feed flow rate of the inert gas is controlled to be ≤2000 L / h and the airflow velocity is ≤500 m / s, the turbine speed is controlled to be 300 rpm / min to 650 rpm / min, the airflow pulverization time is controlled to be 3 minutes to 15 minutes, and the reaction temperature is controlled to be 20°C to 60°C to form a mixed powder.

[0061] In some embodiments, the feed flow rate can be controlled to be 100 L / h to 2000 L / h, the air flow velocity can be controlled to be 10 m / s to 500 m / s, and the temperature can be controlled to be 20° C. to 60° C.

[0062] In some embodiments, the feed flow rate can be controlled to be 500 L / h~2000 L / h, and the air flow velocity can be controlled to be 100 m / s~500 m / s.

[0063] The mass percentage of the ceramic material is 80wt%~98wt%, and the mass percentage of the adhesive is 2wt%~20wt%. The mass percentages of the adhesive and the ceramic material can make the structure of the final ceramic diaphragm relatively stable, and the ceramic material will not separate during the battery charging and discharging cycle. When the adhesive content is lower than 2wt%, the bonding and contact tightness of the components cannot be guaranteed; when the adhesive content is higher than 20wt%, the content of the ceramic material will be reduced, and the ceramic material, which serves as the main insulation function, may not be able to form a sufficient thickness and cover the tabs, thereby causing a short circuit between the positive and negative electrodes.

[0064] In some embodiments, the adhesive is one or more of polytetrafluoroethylene (PTFE), polyhexafluoropropylene (PHTP), or polyvinylidenefluoride (PVDF). Fluorinated ethylene adhesives offer excellent adhesion, insulation, and mechanical strength. The high bond energy of carbon-fluorine bonds prevents functional group decomposition and even failure of the adhesive during high-speed airflow shearing.

[0065] In some embodiments, the adhesive is polytetrafluoroethylene (PTFE), the ceramic material comprises 85% to 95% by weight, and the polytetrafluoroethylene comprises 5% to 15% by weight. PTFE has low van der Waals forces and is loosely packed. Under external shear forces, it transforms from agglomerates into fibrils, which form a three-dimensional network structure and adhere to the ceramic material. The pores within the fibrillated three-dimensional network structure can accommodate the ceramic material, thereby preventing it from falling off the current collector 10 and preventing rapid discharge or even combustion caused by a short circuit between the positive and negative electrodes.

[0066] The ceramic material may be any one or more of oxides (such as boehmite, aluminum oxide, zirconium oxide), carbides (such as silicon carbide, boron carbide), and nitrides (such as silicon nitride).

[0067] The mixed powder is roller-pressed to form a ceramic diaphragm 110. This compaction improves the contact between the ceramic material and the fiberized adhesive in the diaphragm 110 and prevents the ceramic material from falling off. The roller-pressed ceramic diaphragm 110 can serve as a self-supporting membrane, providing sufficient strength to withstand subsequent processing steps and battery charge and discharge cycles.

[0068] In some embodiments, the roll pressing process parameters include a roll speed of ≤ 100 m / min, a main roll pressure of ≤ 300 t, a roll gap of 100 μm to 300 μm, and a roll pressing time of 10 to 50 minutes. The roll speed and pressure are controlled to form a ceramic diaphragm through the mixed powder within a specified timeframe.

[0069] Figure 6 A top view corresponding to the formation of the active material layer 120 in the method for preparing the energy storage cell provided in one embodiment of the present application; Figure 7 for Figure 6 Cross-sectional view along section A1-A2.

[0070] The process steps for forming the positive electrode sheet include: forming an active material layer 120, and the active material layer 120 is located on the active material part 11; wherein, there is a first preset range between the active material layer 120 and the ceramic diaphragm 110, that is, the active material layer 120 and the ceramic diaphragm 110 are spaced apart, and there is a certain gap between the two. This gap can prevent the active material layer 120 and the ceramic diaphragm 110 from abutting against each other during the subsequent thermal curing treatment process, and thus the material between the active material layer 120 and the ceramic diaphragm 110 from mixing.

[0071] In some embodiments, the first preset range is 0.6 mm to 1.8 mm. The value of the first preset range can ensure that within the limited size of the positive electrode sheet, a smaller area is used as a blank foil area, and a larger area is provided for the active material layer and serves as the area where the oxidation reaction of the final positive electrode sheet occurs, thereby improving the energy density of the battery.

[0072] The first preset range may be 0.6 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm or 1.8 mm.

[0073] The active material layer 120 may be composed of a positive electrode active material, a conductive agent, and a first binder.

[0074] The positive electrode active material may be lithium cobalt oxide, lithium iron phosphate or lithium manganese oxide.

[0075] Conductive agents collect microcurrents between active materials and between active materials and current collectors, reducing electrode contact resistance. Conductive agents include traditional conductive agents (such as carbon black, conductive graphite, and carbon fibers) and novel conductive agents (such as carbon nanotubes, graphene, and their mixed conductive pastes).

[0076] The primary adhesive ensures a certain level of bonding strength between active material particles and between the active particles and the current collector during battery operation, and facilitates the formation of the SEI (Solid Electrolyte Interphase) membrane. The primary adhesive can be an oil-based adhesive, such as PVDF, or a water-based adhesive, such as natural cellulose.

[0077] In some embodiments, the process for forming the active material layer 120 includes dissolving 85 wt% to 95 wt% of a positive electrode active material, 5 wt% to 10 wt% of a conductive agent, and 2 wt% to 10 wt% of a first binder in an N-methylpyrrolidone solvent, stirring for 10 to 15 hours under a vacuum of -0.07 MPa to -0.08 MPa and a stirring speed of 1000 rpm to 3500 rpm to obtain a mixture. The mixture is sieved to a 160-mesh screen and subjected to secondary filtration to prepare a positive electrode slurry. The positive electrode slurry is then coated on a current collector and dried to form the active material layer 120. During the mixing process, the slurry temperature is controlled to be no higher than 40°C, and the discharge temperature is controlled at 23 ± 5°C. The mixture is coated on a current collector with a diameter of 15 μm to 20 μm at a coating rate of 5 m / min to 8 m / min.

[0078] In other embodiments, the process for forming the active material layer 120 includes: uniformly dispersing a conductive agent, active material, and binder by high-speed airflow shearing to obtain a conductive powder, wherein the conductive agent comprises 1-2 wt% by weight, the active material comprises 95-97 wt% by weight, and the binder comprises 1-4 wt% by weight; and roller-compacting the conductive powder to obtain the active material layer 120. The dry process for preparing the active material layer 120 results in a high compaction density, thereby enhancing battery capacity. When the binder content is less than 1 wt%, adhesion and contact between the components cannot be ensured. When the binder content is greater than 4 wt%, the battery capacity is reduced, resulting in a lower overall energy density and adversely affecting battery cycling stability. When the active material content is less than 95 wt%, the battery capacity is reduced, resulting in a lower overall energy density that does not meet current energy requirements. When the active material content is greater than 97 wt%, the battery cycling stability is adversely affected. When the content of the conductive agent is lower than 1wt%, a complete conductive network cannot be formed, which is not conducive to the transmission of electrons / ions and the capacity of the electrode material cannot be fully utilized; when the content of the conductive additive is higher than 2wt%, it will lead to a lower overall energy density of the battery.

[0079] It should be noted that the first adhesive in the active material layer is different from the adhesive of the ceramic diaphragm. In other embodiments, the adhesive in the active material layer is the same as the adhesive of the ceramic diaphragm. In other embodiments, the adhesive in the active material layer is one or more of the above-mentioned polytetrafluoroethylene material, polyhexafluoropropylene or polyvinylidene fluoride.

[0080] Figure 8 This is a cross-sectional view of an energy storage cell after heat curing treatment in the preparation method of an embodiment of the present application.

[0081] The process steps for forming the positive electrode sheet include: performing a heat curing treatment, wherein a second preset range is formed between the active material layer 120 and the ceramic diaphragm 110 after the heat curing treatment; the heat curing treatment includes: performing a roller pressing treatment on the current collector 10 including the ceramic diaphragm 110 and the active material layer 120 at a preset temperature to fix the ceramic diaphragm 110 to the current collector 10 and the active material layer 120 to the current collector 10. The heat curing treatment can be a high-temperature calendering composite process. Using a high-temperature calendering composite process to form the positive electrode sheet can effectively increase the compaction density of the ceramic diaphragm and the active material layer in the positive electrode sheet, and can also further increase the degree of entanglement of various substances in the ceramic diaphragm and various substances in the active material layer, thereby improving mechanical properties.

[0082] In some embodiments, the second preset range is 0.5 mm to 1.5 mm. The active material layer 120 and the materials in the ceramic diaphragm 110 do not agglomerate, and the particles in the ceramic diaphragm 110 are stably connected as transmission links, establishing a good ion transmission channel and conductive network, thereby improving the electrochemical performance of the electrode.

[0083] It should be noted that the gap between the ceramic diaphragm and the active material layer after heat curing may be slightly smaller than that between the ceramic diaphragm and the active material layer after heat curing, for example, from 0.6 mm to 0.5 mm. Correspondingly, the thickness of the ceramic diaphragm after heat curing may be slightly smaller than that of the ceramic diaphragm before heat curing; and the thickness H4 of the active material layer after heat curing may be slightly smaller than the thickness H3 of the active material layer before heat curing.

[0084] In some embodiments, the ceramic diaphragm extends to the active material portion, and the distance of the ceramic diaphragm 110 located in the active material portion 11 along the first direction is within a third preset range, and the ratio of the third preset range to the second preset range is 5 to 20. The ratio of the third preset range to the second preset range can be 5, 6, 8, 10, 13, 16, 18, or 20.

[0085] The third preset range L3 is in the range of 0 mm to 1 mm. L3 can be 0 mm, 0.1 mm, 0.3 mm, 0.6 mm, 0.8 mm or 1 mm.

[0086] The preset range L0 between the ceramic diaphragm and the end of the pole lug is in the range of 10 mm to 35 mm. The preset range L0 between the ceramic diaphragm and the end of the pole lug can be 10 mm, 15 mm, 21 mm, 26 mm, 33 mm or 35 mm.

[0087] In some embodiments, the preset temperature is 60° C. to 130° C. At this temperature, the mobility of the particles in each film layer of the positive electrode sheet is enhanced, allowing the particles to move relative to each other, forming a more compact and stable structure under a certain pressure, thereby increasing the compaction density and allowing the lithium ions in the active material layer to dissolve in the electrolyte, thereby increasing the battery capacity.

[0088] Figure 9 A top view corresponding to the formation of a tab in a method for preparing an energy storage cell provided in one embodiment of the present application.

[0089] The process steps for forming the positive electrode sheet include: die-cutting the current collector 10 corresponding to the pole ear portion 12 according to preset parameters, so that the pole ear portion 12 of the current collector 10 forms a pole ear.

[0090] Figure 10This is a top view corresponding to the formation of a positive electrode sheet in the preparation method of the energy storage cell provided in one embodiment of the present application.

[0091] The process steps for forming the positive electrode sheet include: cutting the current collector 10 and forming two identical positive electrode sheets.

[0092] In other embodiments, the heat curing and die-cutting process steps include: die-cutting the current collector 10 corresponding to the tab portion 12 according to preset parameters so that the end of the current collector 10 forms a tab; positioning the ceramic diaphragm 110 at the tab and at the interface between the tab and the active material portion 11; and heat curing the current collector 10. Thus, die-cutting the current collector to form the tab first and then heat curing can avoid damage to the ceramic diaphragm during the die-cutting process, thereby ensuring the stability of the final ceramic diaphragm.

[0093] The preparation method includes: forming a negative electrode sheet.

[0094] The negative electrode sheet 2 includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active layer is located on the negative electrode current collector. Part of the negative electrode current collector is cut into the shape of a tab and serves as a negative electrode tab.

[0095] The negative electrode current collector can be copper foil. Copper foil has low electrical conductivity but high electron transport capacity. Copper foil also has weak lithium insertion capacity and captures fewer lithium ions, thereby effectively reducing lithium ion loss. In other embodiments, the negative electrode current collector can also be a foam copper current collector, a copper mesh current collector, or a three-dimensional nano-copper array current collector.

[0096] In some embodiments, the negative electrode active material layer may be composed of a negative electrode active material, a conductive agent, and a binder. Negative electrode active materials can be classified into two categories: carbon materials and non-carbon materials. Carbon-based materials include graphite materials (natural graphite, artificial graphite, and mesophase carbon spheres) and other carbon-based materials (hard carbon, soft carbon, and graphene). Non-carbon-based materials can be further categorized into titanium-based materials, silicon-based materials, tin-based materials, nitrides, and metallic lithium.

[0097] The conductive agent is similar to that of the positive electrode active material layer. The adhesive for the negative electrode is similar to that of the positive electrode, mainly including oil-based PVDF, water-based CMC, PAMAC, polyvinyl alcohol (PVA), sodium alginate, etc., which will not be repeated here.

[0098] The process steps for forming the negative electrode sheet include: providing a negative electrode current collector; preparing a negative electrode slurry, and coating the negative electrode slurry on a negative electrode current collector with a thickness of 15μm~20μm at a speed of 5m / min~8m / min, die-cutting a portion of the negative electrode current collector according to preset parameters so that the end of the current collector forms a negative electrode tab; cutting the current collector to form two identical negative electrode sheets 2.

[0099] In some embodiments, the preparation step of the negative electrode slurry includes: dissolving 85wt% to 95wt% of the negative electrode active material, 5wt% to 15wt% of the conductive agent and 2wt% to 10wt% of the binder in N-methylpyrrolidone solvent according to the mass ratio, stirring for 12h to 18h under the conditions of vacuum degree of -0.07Mpa to -0.08Mpa and stirring speed of 1000rpm to 3000rpm to obtain a mixture, sieving the mixture to control the mesh specification to 0 mesh, and filtering it through the second stage to prepare the negative electrode slurry.

[0100] Figure 11 A top view of an energy storage cell undergoing a winding process in a method for preparing an energy storage cell provided in one embodiment of the present application.

[0101] The positive electrode sheet 1 and the negative electrode sheet 2 provided above serve as the positive electrode and negative electrode of the energy storage cell, respectively. The positive electrode is the electrode plate where oxidation reaction occurs in the energy storage cell, and the negative electrode is the electrode plate where reduction reaction occurs in the energy storage cell. The positive electrode and the negative electrode are separated and connected together by an electrolyte. The positive electrode and the negative electrode serve as the electrochemical reaction area of ​​the energy storage cell.

[0102] refer to Figure 11 The preparation method includes: forming a diaphragm 3.

[0103] The separator 3 can be located between the positive electrode sheet 1 and the negative electrode sheet 2 to prevent short circuit problems caused by physical contact between the positive electrode sheet 1 and the negative electrode sheet 2, while allowing ions to be conducted through the electrolyte and hindering electron transmission, so that ions and electrons form a circuit during the charge and discharge process of the battery.

[0104] The diaphragm 3 can be any one of a microporous membrane, a modified microporous membrane, a non-woven membrane and a composite membrane. A microporous membrane is a membrane with a pore size in the micrometer range, mainly including polyolefin microporous membranes and other polymer microporous membranes. A modified microporous membrane is a membrane obtained by modifying a microporous membrane. Common modification methods include surface treatment, chemical grafting, surface coating, etc. Non-woven membranes have a small fiber diameter and generally exhibit a higher porosity than other types of membranes. Composite membranes are prepared by coating or filling inorganic materials in microporous membranes or non-woven membranes, and have higher thermal stability and electrolyte wettability than other types of membranes.

[0105] In some embodiments, the separator 3 may be coated with polyvinylidene fluoride (PVDF) material to impart excellent adhesion and flexibility. This excellent adhesion allows for good contact between the separator 3 and the positive electrode sheet 1 or between the separator 3 and the negative electrode sheet 2, thereby reducing assembly time and overall production costs. The separator 3's excellent flexibility also enhances its strength, effectively improving its impact resistance.

[0106] refer to Figure 11 , the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 are wound.

[0107] In some embodiments, the winding process involves winding the separator 3, the positive electrode sheet 1, and the negative electrode sheet 2 into a single core through a winding machine. The order is to wrap the positive electrode sheet 1 with the negative electrode sheet 2, and then separate the positive electrode sheet 1 and the negative electrode sheet 2 with the separator 3.

[0108] In some embodiments, low winding tension will affect the internal resistance and shell penetration rate; excessive tension can easily cause short circuit or fragmentation risks. Therefore, the winding tension is generally between 0.08 and 0.15 MPa for positive tension, 0.08 and 0.15 MPa for negative tension, 0.08 and 0.15 MPa for upper diaphragm tension, and 0.08 and 0.15 MPa for lower diaphragm tension. The width of the negative electrode sheet 2, the width of the positive electrode sheet 1, and the width of the diaphragm 3 are not the same. For example, the width of the negative electrode sheet is 59.5 mm, the width of the positive electrode sheet is 58 mm, and the width of the diaphragm is 61 mm. The three are aligned in the center to improve the alignment of the electrode sheets and avoid the risk of short circuit. The electrode sheet alignment refers to the relative positions of the positive electrode sheet 1, the negative electrode sheet 2, and the diaphragm 3.

[0109] It should be noted that in order to explain and distinguish the diaphragm, positive electrode sheet and negative electrode sheet, Figure 11 The dotted line indicates the separator, the thinner solid line indicates the negative electrode, and the thicker solid line indicates the positive electrode, but this does not represent the thickness relationship between the separator, the positive electrode, and the negative electrode. Figure 11 There are gaps between the middle diaphragm, the positive electrode sheet and the negative electrode sheet. This is to clearly indicate the winding correspondence between the diaphragm, the positive electrode sheet and the negative electrode sheet, but it does not mean that there must be a gap between the diaphragm and the positive electrode sheet or between the diaphragm and the negative electrode sheet. In other words, the diaphragm and the positive electrode sheet can contact each other, or the diaphragm and the negative electrode sheet can contact each other.

[0110] The method for preparing the energy storage cell further includes: placing the whole body formed by winding the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 in a cavity formed by the shell, and the cavity is also filled with electrolyte.

[0111] An electrolyte is a carrier that conducts electrons between the positive and negative electrodes in a battery. In some embodiments, the electrolyte can be an electrolyte solution composed of three parts: a solvent, a lithium salt, and additives. The solvent is used to dissolve the lithium salt and can include cyclic carbonates (PC, EC); linear carbonates (DEC, DMC, EMC); and carboxylates (MF, MA, EA, MA, MP, etc.). The lithium salt can be LiPF6, LiClO4, LiBF4, LiAsF6, etc. Additives can include one or more of the following: film-forming additives, conductive additives, flame retardant additives, overcharge protection additives, additives to control the H2O and HF content in the electrolyte, additives to improve low-temperature performance, and multifunctional additives.

[0112] The preparation method includes: welding the tab, welding the tab to the adapter, connecting the other end of the adapter to the pole, and engaging the top rod with the shell. The adapter is located in the chamber and the pole passes through the top cover.

[0113] Among them, the adapter plate includes at least a first adapter plate and a second adapter plate, the pole includes a positive pole pole and a negative pole pole, the first adapter plate is electrically connected to the pole ear of the positive pole plate 1 and the positive pole pole respectively, and the second adapter plate is electrically connected to the negative pole ear of the negative pole plate 2 and the negative pole pole respectively.

[0114] The beneficial effects of the embodiments of the present application will be further illustrated below in combination with examples and comparative examples.

[0115] Example 1: Boehmite powder and polytetrafluoroethylene material are uniformly dispersed by high-speed air flow shearing to obtain a mixed powder, wherein the mass percentage of boehmite powder is 85wt% and the mass percentage of polytetrafluoroethylene material is 15wt%; the mixed powder is roller-pressed to obtain a ceramic diaphragm.

[0116] Example 2: The difference from Example 1 is that the mass percentage of boehmite powder is 90 wt %, and the mass percentage of polytetrafluoroethylene material is 10 wt %.

[0117] Example 3: The difference from Example 1 is that the mass percentage of boehmite powder is 94 wt %, and the mass percentage of polytetrafluoroethylene material is 6 wt %.

[0118] Comparative Example 1: The difference from Example 1 is that: a ceramic diaphragm is prepared by a wet process, boehmite powder, PVDF particles and NMP solvent are stirred at 50°C until no PVDF particles and boehmite powder are visually observed, to obtain a mixed slurry; the mixed slurry is coated on a current collector and dried.

[0119] Comparative Example 2: The difference from Comparative Example 1 is that after the drying process, the dried ceramic diaphragm is subjected to a roller pressing process.

[0120] Comparative Example 3: The difference from Example 1 is that the mass percentage of boehmite powder is 99 wt %, and the mass percentage of polytetrafluoroethylene material is 1 wt %.

[0121] Comparative Example 4: The difference from Example 1 is that the mass percentage of boehmite powder is 78 wt %, and the mass percentage of polytetrafluoroethylene material is 22 wt %.

[0122] Mechanical tensile strength tests were performed on the above examples and comparative examples, and the test results are summarized and recorded in Table 1. The mechanical tensile strength test is used to characterize the strength of the ceramic diaphragm, and thus the tab's ability to resist tearing. The tear test is used to determine whether the tab has experienced tearing. The ceramic diaphragm defect rate refers to a summary of conditions such as diaphragm damage, poor insulation performance, and detachment of ceramic particles from the diaphragm. The defect rate is determined by the magnitude of the defect.

[0123] Table 1

[0124]

[0125] The experimental data of Examples 1, 2 and 3 above show that high-speed airflow shearing can evenly mix the ceramic material and the adhesive to form a ceramic diaphragm, thereby improving the tensile strength of the ceramic diaphragm and improving the performance of the prepared ceramic diaphragm.

[0126] The experimental data of Example 1, Comparative Example 1 and Comparative Example 2 above show that, compared with ceramic diaphragms prepared by conventional wet process, the ceramic diaphragms prepared by high-speed airflow shearing have higher mechanical strength and stronger tensile strength, thereby making the prepared ceramic diaphragms have better performance.

[0127] The experimental data from Example 1 and Comparative Examples 3 and 4 above show that when the binder content is high, the mechanical strength of the ceramic diaphragm increases, that is, the tensile strength increases, but the defective rate of the positive electrode sheet increases significantly; conversely, although the proportion of ceramic material can be increased to improve the insulation effect of the positive electrode sheet, the low binder content causes the mechanical strength of the ceramic diaphragm to decrease, that is, the tensile strength decreases. The energy storage cell prepared using the ceramic diaphragm provided by the above embodiment includes the following embodiments:

[0128] Example 4: The ceramic diaphragm prepared in Example 2 above; 86 wt% lithium cobalt oxide, 9 wt% conductive agent, and 5 wt% first binder were dissolved in N-methylpyrrolidone solvent according to the mass ratio. The mixture was stirred for 15 hours under a vacuum of -0.07 MPa and a stirring speed of 1000 rpm to obtain a positive electrode slurry. The positive electrode slurry was coated on a current collector and dried to form an active material layer. The current collector containing the ceramic diaphragm and the active material layer was thermally cured to prepare a positive electrode sheet. The negative electrode sheet, positive electrode sheet, and separator were prepared into an energy storage cell. The distance between the active material layer and the ceramic diaphragm was 0.8 mm.

[0129] Example 5: Differing from Example 4, a dry process was used to form the active material layer. A conductive agent, active material, and binder were uniformly dispersed by high-speed airflow shearing to obtain a conductive powder. The weight percentage of the conductive agent was 2 wt%, the weight percentage of the active material was 95 wt%, and the weight percentage of the binder was 3 wt%. The conductive powder was then roll-pressed to obtain the active material layer.

[0130] Example 6: The difference from Example 4 is that the distance between the active material layer and the ceramic diaphragm is 1.2 mm.

[0131] Comparative Example 5: The difference from Example 4 is that the distance between the active material layer and the ceramic diaphragm is 0 mm.

[0132] Comparative Example 6: The difference from Comparative Example 4 is that the distance between the active material layer and the ceramic diaphragm is 2 mm.

[0133] Comparative Example 7: The difference from Example 5 is that the distance between the active material layer and the ceramic diaphragm is 0 mm.

[0134] The above examples and comparative examples were sequentially subjected to a material cross-contamination test and a tear test, and the test results are summarized and recorded in Table 1. The material cross-contamination test is used to determine whether there is any cross-contamination between the ceramic diaphragm and the active material layer, and the tear test is used to determine whether the tab has any tearing. The positive electrode sheet yield refers to a summary of the electrochemical performance, compaction density, and active material particle detachment of the positive electrode sheet. The yield is determined by the magnitude of the performance.

[0135] The cross-contamination test involves using a scanning electron microscope (SEM) to magnify the structure at the junction of the ceramic diaphragm and the active material layer to observe whether the two are in contact and whether the particles are intermingled. If the two are in contact or intermingled, cross-contamination is considered to be present; otherwise, cross-contamination is considered to be absent.

[0136] The tear test involves bending the positive electrode sheet, including the tab, along the direction of the tab and the active material arrangement at an angle of 60° to 120°. After bending 10 times, the surface condition of the tab end is observed under a microscope. If the tab surface shows signs of tearing or even damage, it is considered to have a tear probability, and the tear probability is determined based on the surface condition. If there are no signs, it is considered to have no tear probability.

[0137] The electrochemical test involves: Each example's energy storage cell has a fixed weight of 25g. The cell is fully charged at room temperature (25°C), then allowed to stand for a sufficient period in the test environment. The discharged capacity (energy) is recorded. In actual experiments, the test can be repeated three times and the average value taken for improved accuracy.

[0138] Table 2

[0139]

[0140] The experimental data of the above-mentioned Example 4, Example 5, Comparative Example 7 and Comparative Example 6 show that forming the active material layer through a dry process can avoid the problem of particles of the ceramic diaphragm and the active material layer mixing with each other, and the yield of the positive electrode sheet is higher.

[0141] The experimental data of Example 6, Comparative Example 5 and Comparative Example 6 above show that separating the ceramic diaphragm from the active material layer and controlling the spacing distance can avoid the problem of cross-linking, improve the yield of the positive electrode sheet, and improve the energy density of the energy storage battery. The preparation method of the energy storage battery provided in the embodiment of the present application uses high-speed airflow shearing to evenly mix the ceramic material and the adhesive, rather than using the process of dissolving the adhesive and dispersing the ceramic material with an NMP solution, which can avoid the safety problem of NMP solvent volatilization. Compared with the preparation of the ceramic diaphragm 110 using an NMP solution, the high-speed airflow shearing method can be regarded as preparing the ceramic diaphragm 110 through a dry process. In this process, the adhesive forms friction between the adhesive molecules through the high-speed shear force, thereby generating fibers. This fiber can coat the ceramic material and form a network structure, thereby having good mechanical properties, thereby improving the mechanical properties of the tab and avoiding the tab from tearing. Secondly, a thermal curing treatment is used to form the positive electrode sheet, that is, the current collector 10 including the ceramic diaphragm 110 and the active material layer 120 is subjected to a roller pressing treatment at a preset temperature. This can effectively increase the compaction density of the ceramic and active material layers in the positive electrode sheet, and can also further increase the degree of entanglement of various substances in the tab and the active material layer, thereby improving the mechanical properties.

[0142] Accordingly, according to some embodiments of the present application, the embodiments of the present application further provide an energy storage battery cell, which can be prepared using the preparation method provided in the above embodiments. The technical features that are the same as or corresponding to the above embodiments will not be described in detail here.

[0143] refer to Figure 10 and Figure 11 The energy storage cell includes: a diaphragm 3, and a positive electrode sheet 1 and a negative electrode sheet 2 located on both sides of the diaphragm 3, the positive electrode sheet 1 is prepared by the preparation method of the energy storage cell of any of the above embodiments; the positive electrode sheet 1 includes a current collector 10, a ceramic diaphragm 110 and an active material layer 120, the current collector 10 has a pole ear 13 and an active material portion 11, the ceramic diaphragm 110 is located at least on the pole ear 13 and at the junction between the pole ear 13 and the active material portion 11; the active material layer 120 is located on the active material portion 11, and there is a second preset range L2 between the active material layer 120 and the ceramic diaphragm 110. That is to say, the active material layer 120 and the ceramic diaphragm 110 are spaced apart from each other and do not abut each other. In this way, the problem of cross-contamination between the slurry of the active material layer 120 and the slurry of the ceramic diaphragm 110 can be effectively avoided, and the adsorption problem caused by the combination of the slurry of the active material layer 120 and the slurry of the ceramic diaphragm 110 can be effectively avoided, thereby improving the electron transmission capacity of the lithium-ion battery.

[0144] In some embodiments, the ceramic diaphragm 110 is also located on part of the active material portion 11 , and the distance of the ceramic diaphragm 110 located in the active material portion 11 along the first direction is a third preset range, and the ratio of the third preset range to the second preset range is 5-20.

[0145] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A method for preparing an energy storage battery cell, characterized in that: include: forming a separator and a positive electrode sheet and a negative electrode sheet located on both sides of the separator; The process steps for forming the positive electrode sheet include: Providing a current collector, the current collector having two electrode lugs and an active material portion located between the two electrode lugs; forming a ceramic diaphragm, the ceramic diaphragm being located at least at the electrode ear portion and at the interface between the electrode ear portion and the active material portion, wherein the process steps for forming the ceramic diaphragm include: uniformly dispersing a ceramic material and a binder by high-speed airflow shearing to obtain a mixed powder, wherein the mass percentage of the ceramic material is 80wt% to 98wt% and the mass percentage of the binder is 2wt% to 20wt%; and roller-pressing the mixed powder to obtain the ceramic diaphragm; forming an active material layer, the active material layer being located on the active material portion; wherein a first preset range is defined between the active material layer and the ceramic diaphragm; and the first preset range is 0.6 mm to 1.8 mm; Performing a heat curing treatment, wherein a second preset range is defined between the active material layer and the ceramic diaphragm after the heat curing treatment; the heat curing treatment comprises: performing a roller pressing treatment on the current collector including the ceramic diaphragm and the active material layer at a preset temperature to fix the ceramic diaphragm to the current collector and the active material layer to the current collector; the second preset range is 0.5 mm to 1.5 mm; Die-cutting the current collector corresponding to the tab portion according to preset parameters so that the tab portion of the current collector forms a tab; Cutting the current collector to form two identical positive electrode sheets; The separator, the positive electrode sheet, and the negative electrode sheet are wound together.

2. The method for preparing the energy storage battery cell according to claim 1, wherein: The adhesive is one or more of polytetrafluoroethylene, polyhexafluoropropylene or polyvinylidene fluoride.

3. The method for preparing the energy storage battery cell according to claim 2, wherein: The adhesive is a polytetrafluoroethylene material, the mass percentage of the ceramic material is 85wt% to 95wt%, and the mass percentage of the polytetrafluoroethylene material is 5wt% to 15wt%.

4. The method for preparing the energy storage battery cell according to claim 1, wherein: The process parameters for uniformly dispersing the ceramic material and the adhesive by high-speed airflow shearing to obtain a mixed powder include: a feed flow rate of 100L / h to 2000L / h, an airflow velocity of 10m / s to 500m / s, and a temperature of 20°C to 60°C.

5. The method for preparing the energy storage battery cell according to claim 1, wherein: The preset temperature is 60-130°C.

6. The method for preparing the energy storage battery cell according to claim 1, characterized in that: The process steps for forming the active material layer include: uniformly dispersing the conductive agent, the active material and the adhesive by high-speed airflow shearing to obtain a conductive powder, wherein the mass percentage of the conductive agent is 1wt% to 2wt%, the mass percentage of the active material is 95wt% to 97wt%, and the mass percentage of the adhesive is 1wt% to 4wt%; and rolling the conductive powder to obtain the active material layer.

7. The method for preparing the energy storage battery cell according to claim 1, characterized in that: The process steps of performing the thermal curing treatment and the die-cutting include: die-cutting the current collector corresponding to the pole ear portion according to preset parameters so that the end of the current collector forms a pole ear; the ceramic diaphragm is located at the pole ear and at the junction between the pole ear and the active material portion; and performing the thermal curing treatment on the current collector.

8. An energy storage battery cell, characterized in that: include: A diaphragm, and a positive electrode sheet and a negative electrode sheet located on both sides of the diaphragm, wherein the positive electrode sheet is prepared by the preparation method of the energy storage battery cell according to any one of claims 1 to 7.

9. The energy storage cell according to claim 8, characterized in that: The ceramic diaphragm is also located on a portion of the active material portion. The distance of the ceramic diaphragm located on the active material portion along the first direction is within a third preset range. The ratio of the third preset range to the second preset range is 5-20.

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