A diaphragm, a battery, and an electrical device

Abstract

This invention provides a separator, a battery, and an electrical device. The separator includes a first region and a second region. Along the length of the separator, the second region is located on at least one side of the first region. The first region comprises a porous ceramic material; the second region comprises a negative temperature coefficient ceramic material. This invention addresses the differentiated needs of heating and non-heating areas of the electrode by dividing the separator into functional regions, thereby achieving dynamic adjustment of the current density of the battery electrode and precise improvement of the electrolyte distribution.

Description

Technical Field

[0001] This invention relates to the field of battery materials, and more particularly to a separator, a battery, and an electrical device. Background Technology

[0002] Lithium-ion batteries, as high-energy-density energy storage devices, are widely used in new energy vehicles, energy storage systems, and consumer electronics. Among them, blade-type lithium-ion batteries, due to their compact structure, high energy density, and long cycle life, have become a core component of new energy vehicle power systems. In blade batteries, the uniformity of the electrodes is crucial to battery performance: during charging, lithium ions are extracted from the positive electrode and migrate to the negative electrode for insertion. If the current density distribution is uneven in different areas of the electrodes, it will lead to differences in local reactivity, accelerating battery degradation and even causing safety issues such as lithium plating and thermal runaway.

[0003] In the typical structure of a blade battery, the connection between the negative electrode tab and the terminal post is prone to becoming the main heat-generating area due to concentrated current. This leads to a significant local temperature rise in the electrode, accelerating side reactions such as electrolyte decomposition in the high-temperature region. This further exacerbates the uneven deposition of lithium ions on the negative electrode surface, forming lithium plating failure points. Furthermore, the central region of the battery suffers from limited electrolyte diffusion, resulting in insufficient additive content and utilization of active materials, which also shortens battery life. Therefore, achieving balanced electrode current density and improving electrolyte distribution through material design or structural optimization has become a key technological direction for improving the performance of blade batteries. Summary of the Invention

[0004] This invention provides a separator that, through a functional partition design, enables dynamic adjustment of the current density of the battery electrodes and precise improvement of the electrolyte distribution, thereby extending the battery's lifespan.

[0005] The present invention also provides a battery that, because it includes the above-mentioned separator, has good safety and cycle stability.

[0006] The present invention also provides an electrical device, which, because it includes the aforementioned battery, has stable energy output and a long service life.

[0007] In a first aspect, the present invention provides a diaphragm comprising: a first region and a second region, wherein the second region is located on at least one side of the first region along the length direction of the diaphragm, the first region comprising a porous ceramic material; and the second region comprising a negative temperature coefficient ceramic material.

[0008] In one alternative embodiment, the negative temperature coefficient ceramic material comprises a metal oxide;

[0009] Preferably, the metal oxide comprises at least one of spinel structure, perovskite structure and monoclinic structure.

[0010] Preferably, the metal oxide includes at least one of the following metallic elements: Mn, Co, Ni, Cu, Fe, and V.

[0011] In an optional embodiment, the porous ceramic material includes porous alumina ceramic; the porous alumina ceramic has a pore size of 50-200 nm and a porosity of ≥70%.

[0012] In an alternative embodiment, the second region includes a first coating and a second coating in a direction from adjacent to the base film to away from the base film, wherein the first coating includes vanadium dioxide;

[0013] And / or, the second coating comprises Mn-Co-Ni based NTC thermistor ceramic.

[0014] In an alternative embodiment, the first region includes a first substrate; and / or, the second region includes a second substrate.

[0015] In an optional embodiment, the molar ratio of Mn, Co, and Ni in the Mn-Co-Ni NTC thermistor ceramic is (0.5-0.7):(0.15-0.3):(0.1-0.2).

[0016] In an alternative embodiment, the first coating comprises tungsten-doped vanadium dioxide; wherein, based on the mass of the vanadium dioxide, the amount of tungsten doping is 0.01 wt.% to 0.5 wt.%.

[0017] In an optional embodiment, the total area of ​​the surface of the base film near the first region is A, in cm². 2 The area of ​​the first region is B, in cm. 2 A and B satisfy: 0.1 ≤ B / A ≤ 0.7;

[0018] And / or, the second region is a rectangle, the length of which is the same as the length of the base film, and the width of which is 5%-20% of the width of the base film.

[0019] In a second aspect, the present invention provides a battery comprising a positive electrode, a negative electrode, and a separator as described in the first aspect; the separator is disposed between the positive electrode and the negative electrode; the battery comprises any one of a single cell, a battery module, and a battery pack.

[0020] In one alternative embodiment, the second region is positioned in the lead-out direction of the negative electrode tab;

[0021] Preferably, the second region includes two sides located in the first region and respectively disposed in the lead-out direction of the negative electrode tab and the positive electrode tab.

[0022] Thirdly, the present invention provides an electrical device including the battery described in the fourth aspect.

[0023] This invention divides the separator into functional regions, namely a first region including hydrophilic porous ceramic material and a second region including negative temperature coefficient ceramic material. By utilizing the differences in material properties, it addresses the differentiated needs of the heating and non-heating areas of the electrode, thereby achieving dynamic adjustment of the current density of the battery electrode and precise improvement of the electrolyte distribution, thus extending the battery's lifespan. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0025] Figure 1 This is a schematic diagram of the diaphragm structure according to a specific embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the diaphragm structure according to another specific embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the diaphragm structure in Example 1.

[0028] Figure 4 This is a schematic diagram of battery stacking according to a specific embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of a battery according to a specific embodiment of the present invention.

[0030] Wherein, 1-first region, 2-second region, 3-base film, 4-first coating, 5-second coating. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In this application, the terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0033] In this application, references to "an embodiment," "an example," or "an example" mean that a specific feature, structure, or characteristic described in connection with that embodiment, example, or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination.

[0034] Existing blade batteries mostly use separators made of a single material (such as PE or PP base films), whose function is limited to physically isolating the positive and negative electrodes and allowing lithium ions to pass through. To solve the electrode heating problem, existing technologies typically adopt the following approaches: Electrode structure optimization: By adjusting the shape of the tabs or the thickness distribution of the electrode, the non-uniformity of current density is reduced. However, such solutions are limited by the battery space design and cannot significantly improve the local temperature rise problem. Electrolyte additives: Adding film-forming additives or flame retardants to suppress side reactions at high temperatures. However, additives may reduce lithium-ion transport efficiency and have limited effect on improving electrolyte distribution. Separator coating technology: Existing separator coatings mostly use single-functional materials (such as alumina ceramics), mainly optimizing performance by improving the thermal stability of the separator or the wettability of the electrolyte. For example, alumina coatings can improve electrolyte wettability, but their uniform distribution characteristics make it difficult to specifically solve the problem of abnormal local current density on the electrode.

[0035] To address the aforementioned problems, this invention proposes a method that uses a partitioned design of the membrane functional material, combined with optimized thermistor characteristics and electrolyte wettability, to achieve dynamic adjustment of electrode current density and precise improvement of electrolyte distribution. Specifically, this invention provides the following technical solution:

[0036] In a first aspect, the present invention provides a diaphragm, see [link to diaphragm]. Figure 1 It includes: a first region 1 and a second region 2, wherein the second region is located on at least one side of the first region along the length direction of the diaphragm; the first region includes a porous ceramic material; and the second region includes a negative temperature coefficient ceramic material.

[0037] This invention divides the separator into functional regions: a first region composed of porous ceramic material and a second region composed of negative temperature coefficient ceramic material. The resistance of the second region decreases with increasing temperature. When the area near the negative electrode tab heats up, the corresponding separator resistance decreases, thus forming a controllable microchannel between the positive and negative electrodes. With a constant total current, the increased non-Faraday current generated by the microchannel reduces the Faradaic current generated by the lithium-ion intercalation / deintercalation reaction, thereby slowing down the reaction rate of the electrode near the second region and extending the lifespan of that region. The porous ceramic material in the first region has high electrolyte wettability, and the porous structure design further enhances this wettability, accelerating electrolyte diffusion to the battery center and addressing the issue of insufficient electrolyte distribution in the center. This, in turn, synergistically improves the battery's lifespan compared to the second region.

[0038] It should be noted that the above-mentioned separator is universal and can be used not only in lithium-ion battery systems, but also in sodium-ion batteries and zinc-ion batteries.

[0039] In some embodiments, the second region is located on both sides of the first region, that is, the first region is close to the center of the diaphragm, and the second region is located on both sides of the diaphragm. See [link to previous document]. Figure 1 .

[0040] In one specific embodiment, the negative temperature coefficient ceramic material includes metal oxides.

[0041] Among them, metal oxide-based negative temperature coefficient ceramic materials exhibit a decrease in resistance in this region when the temperature exceeds 45℃, thereby forming a controllable microchannel. Electrons in the negative electrode directly reach the positive electrode through the microchannel, forming a physical current and no longer participating in the electrochemical reaction, thus suppressing the abnormal increase in Faraday current density in this region.

[0042] In some embodiments, during the original charging process, the current density of the electrode region near the second region is 10% higher than that of the electrode region near the first region.

[0043] In one specific embodiment, the metal oxide includes at least one of spinel structure, perovskite structure and monoclinic structure.

[0044] Among them, spinel-structured metal oxides (AB₂O₄) can form multiple valence states and occupy multiple sites at the A and B sites, providing a pathway for electron conduction between B-site ions through a "jumping mechanism." This mechanism is highly sensitive to temperature; therefore, metal oxides including spinel structures can produce a strong and linear negative temperature coefficient (NTC) effect. Perovskite-structured metal oxides exhibit metal-insulator transition characteristics, with their resistivity changing drastically near a specific temperature (Curie temperature Tc). By adjusting the elemental ratio, Tc can be precisely controlled, achieving an extremely high NTC effect near the critical temperature for battery thermal runaway (e.g., 150-200°C), thus providing "switch"-like protection. Monoclinic metal oxides can undergo a reversible phase transition from a low-temperature monoclinic phase (insulator) to a high-temperature rutile phase (metal) at certain temperatures. During this phase transition, the resistivity of the metal oxide can change drastically within a very narrow temperature range. This "abrupt change" characteristic makes it a precise overheat protection switch.

[0045] In some embodiments, spinel-structured metal oxides include, but are not limited to: Mn-Ni-O, Mn-Cu-O, Mn-Fe-O, and Mn-Co-Ni systems. Perovskite-structured metal oxides include, but are not limited to: LaAlO3, LaCoO3, and GdFeO3. Monoclinic metal oxides include, but are not limited to: vanadium dioxide, tungsten, molybdenum, and titanium-doped vanadium dioxide.

[0046] Metal oxides can be formulated with different metal elements according to the performance, stability and cost requirements of the application scenario (such as automotive grade, home appliance grade, consumer electronics grade). In an optional embodiment, the metal oxide includes at least one of the following metal elements: Mn, Co, Ni, Cu, Fe and V.

[0047] To ensure the mechanical properties of the diaphragm, it is understood that the diaphragm also includes a substrate, which includes, but is not limited to, at least one of the following: polypropylene (PP), polyethylene (PE), polypropylene / polyethylene composite (PP / PE), polyimide electrospun material (PI), polypropylene / polyethylene / polypropylene composite (PP / PE / PP), and cellulose nonwoven fabric.

[0048] In some embodiments, the substrate may be blended with at least one of porous ceramic materials and negative temperature coefficient ceramic materials, or may be formed into layered structures.

[0049] In one specific embodiment, the diaphragm includes a base membrane and a coating disposed on at least one side of the base membrane, see [link to relevant documentation]. Figure 1 The coating includes a first region 1 and a second region 2.

[0050] In one specific embodiment, the diaphragm includes a base membrane and coatings disposed on both sides of the base membrane, see [link to relevant documentation]. Figure 2 The coating includes a first region 1 and a second region 2.

[0051] It is understandable that the thickness of the first and second regions is the same.

[0052] The base film material includes, but is not limited to, at least one of the following: polypropylene (PP), polyethylene (PE), polypropylene / polyethylene composite (PP / PE), polyimide electrospun material (PI), polypropylene / polyethylene / polypropylene composite (PP / PE / PP), and cellulose nonwoven fabric.

[0053] In one specific embodiment, the first region includes a first substrate. In this case, the first substrate is blended with a porous ceramic material.

[0054] In other embodiments, the second region includes a second substrate. In this case, the second substrate is blended with a negative temperature coefficient ceramic material.

[0055] The first substrate and the second substrate may be the same or different. For example, the first substrate and the second substrate may each independently include at least one of polypropylene (PP), polyethylene (PE), polypropylene / polyethylene composite (PP / PE), polyimide electrospun material (PI), polypropylene / polyethylene / polypropylene composite (PP / PE / PP), and cellulose nonwoven fabric.

[0056] When the first region and / or the second region are made of mixed materials, the membrane can be prepared using existing conventional processes, such as the blending and melting method: the matrix is ​​mixed with porous ceramic material and negative temperature coefficient ceramic material particles at an appropriate temperature, and then multiple flow channels are set in the extrusion mechanism, each flow channel corresponding to the mixture of matrix and porous ceramic material and the mixture of matrix and negative temperature coefficient ceramic material particles.

[0057] After extrusion and rapid cooling, membranes with different functional zones can be prepared in the direction perpendicular to TD (perpendicular to the conveyor belt).

[0058] In some embodiments, the thickness of the base film is no more than 7 μm, and the thickness of the coating is 1~5 μm. In this embodiment, by limiting the thickness of the base film and the coating, it can be further ensured that when the temperature is too high, a controllable microchannel is formed in the second region. Electrons in the negative electrode can quickly and directly reach the positive electrode through the microchannel to form a physical current, thereby suppressing the abnormal increase of Faraday current density in this region.

[0059] For example, the thickness of the base film is any value or a combination of any two of the following: 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, etc. The thickness of the coating is any value or a combination of any two of the following: 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0060] In one specific embodiment, the porous ceramic material includes porous alumina ceramic; the porous alumina ceramic has a pore size of 50-200 nm and a porosity of ≥70%.

[0061] Among them, the above porous ceramic materials can ensure rapid electrolyte penetration (wetting time ≤ 5s), significantly increase the electrolyte wetting area, significantly improve the charge transport dynamics in the central region of the battery, and thus enable the first region to achieve uniform electrolyte distribution while maintaining mechanical strength, reducing capacity decay caused by polarization effect.

[0062] For example, the pore size of the porous alumina ceramic is any value or a range of any two of the following: 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, etc. The porosity is any value or a range of any two of the following: 70%, 80%, 90%, etc.

[0063] In some embodiments, the pore size distribution of porous alumina ceramics is calculated based on the BJH model using the adsorption-desorption isotherm of gas (N2) at low temperature (77K liquid nitrogen).

[0064] The porosity of porous alumina ceramics can be directly observed by scanning electron microscopy to determine the surface or cross-sectional morphology, and the pore size distribution can be statistically analyzed and the porosity calculated using image analysis software (such as ImageJ).

[0065] In one specific embodiment, the second region, in the direction from the adjacent base film to the direction away from the base film, includes a first coating 4 and a second coating 5, see [link to previous embodiment]. Figure 3 The first coating includes vanadium dioxide. Vanadium dioxide is a special type of NTC thermistor, characterized by extremely high resistance below 68°C and extremely low resistance above 68°C. This characteristic determines that VO2 acts as a "switch".

[0066] In one specific embodiment, the second coating comprises a Mn-Co-Ni based NTC thermistor ceramic. The operating temperature range of the Mn-Co-Ni based NTC thermistor matches that of the lithium battery (25°C to 60°C). The high Mn content provides a high resistance value, ensuring that excessive leakage current during use will not cause abnormal local temperature increases in the battery.

[0067] In one specific embodiment, the molar ratio of Mn, Co, and Ni in the Mn-Co-Ni based NTC thermistor ceramic is (0.5-0.7):(0.15-0.3):(0.1-0.2).

[0068] In the above embodiments, by precisely controlling the element ratio, NTC ceramics can exhibit linear response characteristics within the target temperature range (25-60℃), ensuring the reliability of the thermal management system. Specifically, Mn, as the main dopant element (0.5-0.7 molar ratio), provides a high initial resistivity, Co (0.15-0.3 molar ratio) optimizes the response slope in the mid-temperature region by adjusting the d-orbital electron filling, and Ni (0.1-0.2 molar ratio) enhances lattice stability.

[0069] In an alternative embodiment, the first coating comprises tungsten-doped vanadium dioxide; wherein, based on the mass of vanadium dioxide, the doping amount of tungsten is 0.01 wt.% to 0.5 wt.%.

[0070] Tungsten doping can lower the insulating-metal transition temperature (MIT) of vanadium dioxide by replacing vanadium atoms in the vanadium dioxide lattice. When the tungsten doping amount is 0.1 wt.%, the MIT temperature decreases from 68°C to 52°C, matching the thermal runaway warning temperature (45-55°C) of lithium batteries. When the doping amount exceeds 0.5 wt.%, the MIT temperature continues to decrease, but the material stability decreases. Therefore, the preferred tungsten doping amount is 0.01 wt.% to 0.5 wt.%.

[0071] For example, the tungsten doping amount is any value or a range of any two of 0.01 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%.

[0072] In one specific embodiment, the total area of ​​the base film surface near the first region is A, in cm². 2 The area of ​​the first region is B, in cm². 2 A and B satisfy: 0.6≤B / A≤0.7.

[0073] The base film has two functional surfaces, upper and lower, and the total area of ​​the surface closer to the first region is A.

[0074] The above implementation method maximizes the optimization of electrolyte distribution by controlling the B / A ratio within the range of 0.6-0.7, ensuring that the first region covers 60-70% of the battery center area.

[0075] For example, B / A is any value or a range of any two of the following: 0.6, 0.62, 0.65, 0.67, 0.7, etc.

[0076] In one specific embodiment, the second region is rectangular, with the length of the rectangle being the same as the length of the base film, and the width of the rectangle accounting for 5%-20% of the width of the base film. The second region is designed as a rectangle of a specific size to precisely cover the tab lead-out direction, ensuring a high degree of matching between the functional zoning and the battery structural features, thereby further improving the battery's operational stability.

[0077] For example, the width of the rectangle is any value or a range of any two of the following: 5%, 10%, 15%, 20% of the width of the base film.

[0078] In a second aspect, the present invention provides a battery comprising a positive electrode, a negative electrode, and a separator as described in the first aspect; the separator is disposed between the positive electrode and the negative electrode, see [reference]. Figure 4 Batteries include any one of the following: individual cells, battery modules, and battery packs.

[0079] The present invention does not specifically limit the composition and material of the positive and negative electrode sheets of the battery. Exemplarily, the negative electrode sheet includes a current collector and a negative electrode active material layer located on at least one surface of the current collector. The negative electrode active material layer includes hard carbon material, conductive agent, binder and dispersant. The conductive agent can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotube, metal powder and graphene. The binder can be selected from at least one of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyvinyl alcohol and sodium polyacrylate. The dispersant can be selected from at least one of sodium carboxymethyl cellulose, triethylhexyl phosphate and sodium dodecyl sulfate. The negative electrode current collector can be a conventional negative electrode current collector in the art, such as copper foil. In some embodiments, the negative electrode active material layer comprises: hard carbon material, sodium carboxymethyl cellulose, styrene-butadiene rubber, and carbon black in a mass ratio of 100:1.5:3:1.5.

[0080] The aforementioned positive electrode sheet includes a current collector and a positive electrode active material layer located on at least one surface of the current collector. The positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese phosphate, lithium iron phosphate, and lithium manganese iron phosphate. The conductive agent includes the aforementioned hard carbon material and, optionally, at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, metal powder, and graphene. The binder may be selected from at least one of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate. The material of the positive electrode current collector may be selected from any one or more of copper foil, titanium foil, tin foil, chromium foil, and composite foils of the above metals.

[0081] Because the negative electrode tab and terminal post are the main heat sources during charging of existing blade-type lithium-ion batteries, resulting in a higher temperature rise of the electrode sheet near the negative electrode tab, the second region is preferentially located in the lead-out direction of the negative electrode tab. (See [reference]). Figure 5 .

[0082] In one specific embodiment, the second region includes two sides located in the first region and respectively disposed in the lead-out directions of the negative electrode tab and the positive electrode tab. The fact that the second region is disposed in the lead-out directions of the negative electrode tab and the positive electrode tab allows for simultaneous control of the thermal effect of both electrodes.

[0083] For example, the battery described above can be prepared by a method including the following process: stacking the positive electrode, separator and negative electrode in sequence to obtain a cell or stacking the positive electrode, separator and negative electrode in sequence, and optionally winding them to obtain a cell; placing the cell in a battery packaging film shell (such as an aluminum-plastic film shell), injecting electrolyte into the outer packaging and sealing it to obtain the battery of the present invention.

[0084] Exemplarily, the battery further includes an electrolyte comprising an organic solvent and an electrolyte salt. The organic solvent serves as a medium for ion transport in the electrochemical reaction and can be any organic solvent known in the art for use in battery electrolytes. Exemplarily, the organic solvent can be at least one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butenyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0085] For example, the battery of the present invention can be manufactured according to conventional methods in the art. For instance, the positive electrode, separator and negative electrode can be stacked in sequence, and then assembled into a cell by a winding process or a stacking process. After packaging and baking, electrolyte is injected, and then the battery is manufactured by hot pressing and other processes.

[0086] Thirdly, the present invention provides an electrical device including the battery of the second aspect.

[0087] It should be noted that the above-mentioned electrical equipment can be any equipment that conventionally requires electricity, such as, but not limited to, computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0088] To further understand the present invention, the technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0089] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0090] Example 1

[0091] This example provides a separator, including a PE base film and a coating disposed on one side surface of the base film. The coating includes a first region and a second region, with the second region located on both sides of the first region. See [link to documentation]. Figure 1The base film is 310 mm long, 160 mm wide, and 7 μm thick. The coating is 2 μm thick. The first region is 210 mm long and 160 mm wide, and the second region is 50 mm long and 160 mm wide. The first region is made of porous alumina ceramic (pore size 50-200 nm). The second region consists of two layers: the layer closer to the base film is made of monoclinic vanadium dioxide (1.5 μm thick), and the layer further away from the base film is made of Mn-Co-Ni based NTC thermistor ceramic (specifically composed of Mn...). 0.6 Co 0.2 Ni 0.2 (with a thickness of 1.5 μm).

[0092] Example 2-11

[0093] The difference from Example 1 is that the parameters in Table 1 are changed.

[0094] Example 12

[0095] This example provides a diaphragm, including a first region and a second region, with the second region located on both sides of the first region. The first region is 210 mm long and 160 mm wide, and the second region is 50 mm long and 160 mm wide. The first region is a mixture of porous alumina ceramic (pore size 50-200 nm) and a PE matrix. The second region comprises two layers: one layer is a mixture of vanadium dioxide and a PE matrix (thickness 1.5 μm), and the other layer is a Mn-Co-Ni based NTC thermistor ceramic (specifically composed of Mn...). 0.6 Co 0.2 Ni 0.2 The mixture of the material and the PE matrix (thickness 1.5μm) is used; the positional relationship between the two layers is as described in Example 1.

[0096] Comparative Example 1

[0097] The difference from Example 1 is that the diaphragm is only a base film with a thickness of 7 μm.

[0098] Comparative Example 2

[0099] The difference from Example 1 is that the diaphragm does not contain the first region, that is, the coating is all in the second region.

[0100] Comparative Example 3

[0101] The difference from Example 1 is that the diaphragm does not contain a second region, that is, the coating is all in the first region.

[0102] Application examples

[0103] The battery manufacturing process includes the following steps:

[0104] 1. Positive electrode sheet: Weigh lithium iron phosphate: PVDF binder: carbon nanotubes: carbon black in a mass ratio of 100:1.5:0.5:0.5, disperse the weighed raw materials in NMP to prepare a positive electrode slurry, coat it on the surface of a 13μm aluminum foil, dry and compact it to obtain the positive electrode sheet;

[0105] 2. Negative electrode sheet: Weigh out graphite:SBR binder:CMC thickener:carbon black in a mass ratio of 100:1.2:1.5:0.5, disperse the weighed raw materials in deionized water to prepare a negative electrode slurry, coat it on the surface of a 6μm copper foil, dry and compact it to obtain the negative electrode sheet;

[0106] 3. Diaphragm: The diaphragm of the above embodiments or comparative examples;

[0107] 4. Stacking method: Layering, the second region should be placed on the electrode sheets near the positive and negative tabs, hot-pressed to obtain the battery.

[0108] Performance testing

[0109] At 45°C, the battery was charged to 3.45V at 1C, then to 3.75V at 0.2C, and left to stand for 30 minutes. Then it was discharged to 2.0V at 1C and left to stand for 30 minutes. This cycle was repeated 1500 times, and the voltage, current, temperature, and charge / discharge capacity were recorded during the cycle.

[0110] The test results are summarized in Table 1.

[0111] Table 1:

[0112]

[0113] As can be seen from Table 1, compared with the comparative example, the separator of the embodiment improves the battery life by dividing the functional areas.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diaphragm, characterized in that, include: A first region and a second region are located along the length of the diaphragm, with the second region situated on at least one side of the first region. The first region comprises a porous ceramic material, and the second region comprises a negative temperature coefficient ceramic material.

2. The diaphragm according to claim 1, characterized in that, The negative temperature coefficient ceramic material includes metal oxides; Preferably, the metal oxide comprises at least one of spinel structure, perovskite structure and monoclinic structure; Preferably, the metal oxide includes at least one of the following metallic elements: Mn, Co, Ni, Cu, Fe, and V.

3. The diaphragm according to claim 1, characterized in that, The porous ceramic material includes porous alumina ceramic; the pore size of the porous alumina ceramic is 50-200 nm, and the porosity is ≥70%.

4. The diaphragm according to any one of claims 1-3, characterized in that, The diaphragm includes a base membrane, and the second region includes a first coating and a second coating in a direction from adjacent to the base membrane to away from the base membrane, wherein the first coating includes vanadium dioxide; And / or, the second coating comprises Mn-Co-Ni based NTC thermistor ceramic.

5. The diaphragm according to any one of claims 1-3, characterized in that, The first region includes a first substrate; and / or, the second region includes a second substrate.

6. The diaphragm according to claim 4, characterized in that, In the Mn-Co-Ni NTC thermistor ceramic, the molar ratio of Mn, Co and Ni is (0.5-0.7):(0.15-0.3):(0.1-0.2).

7. The diaphragm according to claim 4, characterized in that, The first coating comprises tungsten-doped vanadium dioxide; wherein, based on the mass of the vanadium dioxide, the tungsten doping amount is 0.01 wt.% to 0.5 wt.%.

8. The diaphragm according to any one of claims 4-7, characterized in that, The total area of ​​the base film surface near the first region is A, in cm². 2 The area of ​​the first region is B, in cm. 2 A and B satisfy: 0.1 ≤ B / A ≤ 0.7; And / or, the second region is a rectangle, the length of which is the same as the length of the base film, and the width of which is 5%-20% of the width of the base film.

9. A battery, characterized in that, The battery includes a positive electrode, a negative electrode, and a separator as described in any one of claims 1-8; the separator is disposed between the positive electrode and the negative electrode; the battery includes any one of a single cell, a battery module, and a battery pack.

10. The battery according to claim 9, characterized in that, The second region is positioned in the direction of the negative electrode tab's lead-out; Preferably, the second region includes two sides located in the first region and respectively disposed in the lead-out direction of the negative electrode tab and the positive electrode tab.

11. An electrical appliance, characterized in that, Includes the battery as described in claim 9 or 10.

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