Positive plate, battery cell for cylindrical battery and cylindrical battery

Abstract

The utility model relates to a positive plate, a battery cell for a cylindrical battery and the cylindrical battery. An active material coating area, a ceramic coating area and an empty foil area are sequentially arranged on the two faces of the positive plate in the width direction, and the width ratio and the thickness ratio of the ceramic coating on each face relative to the active material layer on the face are controlled. Therefore, the cylindrical battery using the roll core containing the positive plate can effectively reduce short circuit of the positive electrode and the negative electrode caused by poor diaphragm wrapping or metal scraps generated in the rubbing process or direct contact between the positive plate and the negative plate, and the safety performance of the battery is improved.

Description

Technical Field

[0001] This utility model generally relates to the field of energy storage technology, particularly the field of lithium-ion secondary batteries and sodium-ion secondary batteries; specifically, this utility model relates to a positive electrode sheet for a cylindrical battery, a cylindrical battery cell including the same, and a cylindrical battery including the same. Background Technology

[0002] Secondary batteries can be categorized by shape into cylindrical batteries, prismatic batteries, and pouch batteries. Cylindrical batteries typically use a winding process to manufacture their bare cells, which are then encapsulated in a cylindrical casing. Cylindrical batteries offer advantages such as good consistency, high production efficiency, and strong system-level heat dissipation.

[0003] Cylindrical bare cells are made by winding multiple layers of thin film materials (usually including separator, negative electrode, separator and positive electrode). After winding, the core needs to be flattened. During the flattening process, metal debris will be generated, which can easily cause short circuits between the positive and negative electrodes of the core. In addition, if the separator is not properly covered, there is also a risk of short circuits and battery failure. Utility Model Content

[0004] This utility model was made in view of the above-mentioned problems existing in the prior art.

[0005] In a first aspect, the present invention relates to a positive electrode sheet, comprising a current collector, the current collector having a first surface and a second surface in its thickness direction and a first end edge and a second end edge in its width direction, and wherein, in the width direction from the first end edge to the second end edge, the current collector has, sequentially disposed on the first surface, a first active material coating region, a first ceramic coating region adjacent to the first active material coating region, and a first empty foil region adjacent to the first ceramic coating region without any coating; and on the second surface, a second active material coating region, a second ceramic coating region adjacent to the second active material coating region, and a second empty foil region adjacent to the second ceramic coating region without any coating are sequentially disposed.

[0006] The widths of the first ceramic coating region and the first active material coating region are C1 and D1, respectively, where C1 / D1 = 0.02-0.06.

[0007] The widths of the second ceramic coating region and the second active material coating region are C2 and D2, respectively, where C2 / D2 = 0.02-0.06.

[0008] The ceramic coating thickness of the first ceramic coating region is Dc1, the active material coating thickness of the first active material coating region is Dd1, the ceramic coating thickness of the second ceramic coating region is Dc2, and the active material coating thickness of the second active material coating region is Dd2. The ratios of Dc1 / Dd1 and Dc2 / Dd2 are each independently 0.50-0.86.

[0009] In a second aspect, this utility model relates to a cell for cylindrical batteries, comprising:

[0010] The positive electrode sheet according to the first aspect of this utility model;

[0011] Negative electrode; and

[0012] First diaphragm and second diaphragm;

[0013] The battery cell is wound into a jelly roll structure, and a first separator and a second separator separate the positive electrode and the negative electrode.

[0014] When viewed from the center outwards, the cell sequentially comprises a positive electrode, a first separator, a negative electrode, and a second separator.

[0015] In a third aspect, this utility model relates to a cylindrical battery, which includes:

[0016] A cylindrical battery cell according to the second aspect of this utility model, disposed inside a cylindrical battery casing;

[0017] The cylindrical battery cell is configured such that the empty foil area of ​​its positive electrode is close to the positive terminal, and the active material coating area of ​​its positive electrode is close to the negative terminal.

[0018] The applicant discovered that by using the positive electrode sheet with the defined structure, it is possible to effectively reduce the short circuit between the positive and negative electrodes in cylindrical batteries caused by poor separator wrapping or metal debris generated during the core rolling process, thereby improving the battery's safety performance; and the ceramic layer, to a certain extent, blocks the direct contact between the positive and negative electrode sheets, reducing the occurrence of fire and explosion after needle puncture. Attached Figure Description

[0019] To more clearly illustrate the technical solution of this utility model, the following description will be provided in conjunction with the accompanying drawings. It should be understood that these drawings are merely for the purpose of facilitating a better understanding of this utility model by those skilled in the art, and are not intended to limit the scope of this utility model, wherein:

[0020] Figure 1 The structure of the positive electrode of this invention is schematically shown.

[0021] Figure 2 The structure of the cylindrical battery cell of this invention is schematically shown.

[0022] Figure 3 The diagram schematically illustrates the dimensional and positional relationships of the positive electrode, the first separator, the negative electrode, and the second separator in the thickness direction of a cylindrical battery cell of the present invention in its unfolded state.

[0023] Figure 4-11 The diagrams schematically illustrate the dimensional and positional relationships of the positive electrode, the first separator, the negative electrode, and the second separator in the width and thickness directions of other cylindrical battery cells with different configurations of this invention in their unfolded state.

[0024] Figure 12 The structure of the cylindrical battery of this invention is schematically shown.

[0025] Figure 13 The fabrication of the positive electrode in the embodiment is illustrated schematically. Detailed Implementation

[0026] To make the utility model objectives, technical solutions, and beneficial technical effects of this application clearer, this application will be described in detail below. It should be noted that the various aspects, features, embodiments, and advantages described in this application can be compatible and / or combined together.

[0027] Unless otherwise specified, the technical terms used in this specification have the same meaning as commonly understood by those skilled in the art.

[0028] In this application, unless otherwise specified, temperature refers to room temperature (°C), atmosphere refers to air atmosphere, and pressure refers to atmospheric pressure.

[0029] In this application, unless otherwise specified, when referring to the “width” or “thickness” of a coating or area, it means the average “width” or average “thickness” of that coating or area.

[0030] In this application, when two dimensions, such as X1 and X2, are referred to as "substantially identical," it means that the deviation between their sizes does not exceed 10%, i.e., the ratio of their sizes, X2 / X1, is 0.90-1.10, for example, 0.90, 0.95, 1.00, 1.05, 1.10, or a range defined by any two thereof. When two dimensions, such as X1 and X2, are referred to as "identical" or X2 = X1, it means that the difference in their sizes is within the operating tolerance.

[0031] Those skilled in the art will understand that, unless otherwise specified, in this application, a number containing n significant digits after the decimal point actually also includes the result of rounding a number with more significant digits after the decimal point to n significant digits. For example, 0.9 actually covers all numbers in the range from greater than or equal to 0.85 to less than 0.95; 0.90 actually covers all numbers in the range from greater than or equal to 0.895 to less than 0.905; and 0.95 actually covers the range from greater than or equal to 0.945 to less than 0.955. 1.0 covers all numbers within the range of 0.95 to less than 1.05; 1.00 covers all numbers within the range of 0.995 to less than 1.005; 1.05 covers all numbers within the range of 1.045 to less than 1.055; 1.1 covers all numbers within the range of 1.05 to less than 1.15; 1.10 covers all numbers within the range of 1.096 to less than 1.105; and so on.

[0032] In this application, "positive electrode", "positive electrode sheet" and "positive electrode plate" have the same meaning and can be used interchangeably, referring to a structure including a current collector and a layer of positive electrode active material formed on the surface of the current collector.

[0033] In this application, "negative electrode", "negative electrode sheet" and "negative electrode plate" have the same meaning and can be used interchangeably, referring to a structure including a current collector and a layer of positive electrode active material formed on the surface of the current collector.

[0034] In this application, the term "cell" refers to a jelly roll structure formed by stacking and winding a positive electrode, a negative electrode, and a separator, wherein the separator separates the positive and negative electrodes. It can also be called a "core," and the two have the same meaning and are used interchangeably.

[0035] In this application, when two components or areas are referred to as "adjacent", it means that the two components or areas are in contact and there are no other components or areas between them.

[0036] In this application, for the positive electrode, negative electrode, and separator, length refers to the dimension with the largest size among the two dimensions in the direction parallel to its surface, i.e., the size along the winding direction; width or height (the two can be used interchangeably in this application) refers to the dimension with the smallest size among the two dimensions in the direction parallel to its surface, i.e., the size in the in-plane direction perpendicular to the winding direction, in other words, the size in the height direction of the core; thickness refers to its size in the direction perpendicular to the surface; length > width (height) > thickness.

[0037] This utility model relates to a positive electrode sheet, a cylindrical battery cell including the same, and a cylindrical battery including the same.

[0038] The present invention will be described in detail below.

[0039] Electrode plates

[0040] In a first aspect, the present invention relates to a positive electrode sheet comprising a current collector, the current collector having a first surface and a second surface in its thickness direction and a first end edge and a second end edge in its width direction, and wherein, in the width direction from the first end edge to the second end edge, the current collector has, sequentially disposed on the first surface, a first active material coating region, a first ceramic coating region adjacent to the first active material coating region, and a first empty foil region adjacent to the first ceramic coating region without any coating; and on the second surface, a second active material coating region, a second ceramic coating region adjacent to the second active material coating region, and a second empty foil region without any coating are sequentially disposed.

[0041] The widths of the first ceramic coating region and the first active material coating region are C1 and D1, respectively, where C1 / D1 = 0.02-0.06.

[0042] The widths of the second ceramic coating region and the second active material coating region are C2 and D2, respectively, where C2 / D2 = 0.02-0.06.

[0043] The ceramic coating thickness of the first ceramic coating region is Dc1, the active material coating thickness of the first active material coating region is Dd1, the ceramic coating thickness of the second ceramic coating region is Dc2, and the active material coating thickness of the second active material coating region is Dd2. The ratios of Dc1 / Dd1 and Dc2 / Dd2 are each independently 0.50-0.86.

[0044] The applicant discovered that by using a positive electrode sheet with a specific structure, the short circuit between the positive and negative electrodes in cylindrical batteries caused by poor separator wrapping or metal debris generated during the core rolling process was effectively reduced, thus improving the battery's safety performance; and the ceramic layer, to a certain extent, blocked the direct contact between the positive and negative electrode sheets, reducing the occurrence of fire and explosion after needle puncture.

[0045] In this invention, each surface of the positive electrode is divided into an active material coating area, a ceramic coating area, and an empty foil area arranged sequentially in the thickness direction.

[0046] In the implementation, C1 / D1 and C2 / D2 are each independently 0.02-0.06, for example, 0.02, 0.03, 0.04, 0.05, 0.06, or a range defined by any two thereof. Preferably, C1 / D1 and C2 / D2 are substantially the same, more preferably the same. More preferably, C1 and C2 are substantially the same, more preferably the same, i.e., C1 = C2, and D1 and D2 are substantially the same, more preferably the same, i.e., D1 = D2.

[0047] In the implementation, Dc1 / Dd1 and Dc2 / Dd2 are each independently 0.50-0.86, for example, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.86, or a range defined by any two thereof. Preferably, Dc1 and Dc2 are substantially the same, preferably identical, i.e., Dc1 = Dc2; and / or Dd1 and Dd2 are substantially the same, preferably identical, i.e., Dd1 = Dd2; and / or Dc1 / Dd1 and Dc2 / Dd2 are substantially the same, preferably identical, i.e., Dc1 / Dd1 = Dc2 / Dd2.

[0048] Preferably, the positive electrode sheet satisfies one or more of the following conditions (1)-(4), preferably all of them: (1) C1 = C2, (2) D1 = D2, (3) Dc1 = Dc2, and (4) Dd1 = Dd2.

[0049] When the positive electrode sheet meets one or more of the above conditions, it can more effectively reduce the short circuit between the positive and negative electrodes in the cylindrical battery caused by poor separator wrapping or metal debris generated during the core rolling process, thereby improving the battery's safety performance; when all of the above conditions are met, the effect is further improved.

[0050] In a preferred embodiment, (Dc1+Dc2) / (Dd1+Dd2+d1) is 0.50-0.60, for example, 0.50, 0.55, 0.60, or a range defined by any two thereof, where d1 is the thickness of the positive electrode current collector. Within this range, short circuits between the positive and negative electrodes in cylindrical batteries caused by poor separator wrapping or metal debris generated during the core-rolling process can be reduced more effectively, thus improving battery safety performance.

[0051] There are no particular limitations on the thickness d1 of the positive electrode current collector, and it can be a commonly used thickness in the field of batteries (such as lithium batteries and sodium batteries), such as 5-50 μm, 10-20 μm, or 10-15 μm.

[0052] There are no particular restrictions on the material of the positive electrode current collector, and materials commonly used by those skilled in the art can be used, such as metal foils like aluminum foil, nickel foil, etc.

[0053] The thickness of the first positive electrode active material layer and the second positive electrode active material layer is not particularly limited, and can be, for example, independently 10-100 μm (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 μm, or a range defined by any two thereof).

[0054] In this embodiment, the positive electrode sheet has first and second empty foil regions on its first and second surfaces, respectively. By providing empty foil regions, it is beneficial to reduce short circuits between the positive and negative electrodes caused by poor separator wrapping or metal debris generated during the core rolling process, thereby improving battery safety performance; the larger the width ratio of the empty foil region to the active material region, the better this effect. However, considering the need to significantly maximize the above-mentioned effects of the empty foil regions and reduce the reduction in active material coating area caused by the presence of empty foil regions on the current collector, thus reducing energy density, it is preferable that the width ratios B1 / D1 and B2 / D2 of the empty foil region to the active material region are each independently 0.01-0.06, for example 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, or a range defined by any two thereof. Preferably, B1 / D1 and B2 / D2 are substantially the same, preferably the same, i.e., B1 / D1 = B2 / D2. More preferably, B1 and B2 are substantially the same, preferably the same, i.e., B1 = B2.

[0055] The positive electrode sheet is a battery positive electrode sheet, such as a positive electrode sheet for lithium-ion batteries or sodium-ion batteries, for example, a positive electrode sheet for cylindrical lithium batteries or sodium batteries. In other words, the first positive electrode active material and the second positive electrode active material can be positive electrode active materials for lithium-ion batteries or sodium-ion positive electrode active materials.

[0056] The first active material coating region may, for example, be coated with a first active material coating formed of a mixture of a first positive electrode active material, such as a first lithium-ion battery or sodium-ion battery layered oxide positive electrode material, a first conductive agent, and a first binder. The second active material coating region may, for example, be coated with a second active material coating formed of a mixture of a second positive electrode active material, such as a second lithium-ion battery or sodium-ion battery layered oxide positive electrode material, a second conductive agent, and a second binder. The first active material coating and the second active material coating may be the same or different in composition. For example, the first positive electrode active material (e.g., a layered oxide positive electrode material for a first lithium-ion battery or sodium-ion battery) in the first active material coating may be the same as or different from the second positive electrode active material (e.g., a layered oxide positive electrode material for a second lithium-ion battery or sodium-ion battery) in the second active material coating; and / or the content of the first positive electrode active material (e.g., a layered oxide positive electrode material for a first lithium-ion battery or sodium-ion battery) in the first active material coating may be the same as or different from the content of the second positive electrode active material (e.g., a layered oxide positive electrode material for a second lithium-ion battery or sodium-ion battery) in the second active material coating; the first conductive agent in the first active material coating may be the same as or different from the second conductive agent in the second active material coating; and / or the content of the first conductive agent in the first active material coating may be the same as or different from the content of the second conductive agent in the second active material coating; and / or the first binder in the first active material coating and the second binder in the second active material coating may be the same as or different from the content of the first binder in the first active material coating and the second binder in the second active material coating, all of which will not depart from the spirit and scope of this utility model. However, from the perspective of simplifying the manufacturing process, preferably, the first active material coating and the second active material coating have the same composition; that is, the first positive electrode active material (e.g., the first lithium-ion battery or sodium-ion battery layered oxide positive electrode material) in the first active material coating is the same as the second positive electrode active material (e.g., the second lithium-ion battery or sodium-ion battery layered oxide positive electrode material) in the second active material coating, and the content of the first positive electrode active material (e.g., the first lithium-ion battery or sodium-ion battery layered oxide positive electrode material) in the first active material coating is the same as the content of the second positive electrode active material (e.g., the second lithium-ion battery or sodium-ion battery layered oxide positive electrode material) in the second active material coating; the first conductive agent in the first active material coating is the same as the second conductive agent in the second active material coating, and the content of the first conductive agent in the first active material coating is the same as the content of the second conductive agent in the second active material coating; and the first binder in the first active material coating and the second binder in the second active material coating are the same as the content of the first binder in the first active material coating and the second binder in the second active material coating.

[0057] The first and second positive electrode active materials are not particularly limited, and can be, for example, positive electrode active materials for lithium-ion batteries or sodium-ion batteries, such as layered metal oxides (e.g., lithium-ion battery layered metal oxides such as lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide) or sodium-ion battery layered metal oxides (e.g., α-NaFeO2 type) (e.g., having the general formula Na x M y O 2-δ A z Where M is selected from one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg, and A is, for example, selected from one or more of S, N, F, Br, Cl, I, CN, etc., and the values ​​of each subscript ensure that the general formula satisfies valence balance. For example, the positive electrode active material can be NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 One or more of the following: O2, Na2FeP2O7, Na4Fe3(PO4)2(P2O7), Na3V2(PO4)3, NaFePO4 and NaMnFe(CN)6, etc.; one or more of the following: polyanionic compounds and Prussian blue compounds.

[0058] The first and second binders are not particularly limited and can be appropriately selected according to the positive electrode active material used. For example, when the positive electrode active material used is a lithium-ion or sodium-ion battery positive electrode active material, it can be one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), styrene-butadiene rubber (SBR), aqueous acrylic resin, and carboxymethyl cellulose (CMC), such as polyvinylidene fluoride (PVDF).

[0059] There are no particular limitations on the first and second conductive agents, and they can be appropriately selected according to the positive electrode active material used. For example, when the positive electrode active material used is a lithium-ion or sodium-ion battery positive electrode active material, it can be, for example, one or more selected from graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0060] The first ceramic coating region may, for example, be coated with a coating formed of a mixture of, for example, a first ceramic material and a third binder. The second ceramic coating region may, for example, be coated with a coating formed of a mixture of, for example, a second ceramic material and a fourth binder. The first and second ceramic coating regions may be the same or different in composition. For example, the first ceramic material in the first ceramic coating region may be the same or different from the second ceramic material in the second ceramic coating region; and / or the content of the first ceramic material in the first ceramic coating region may be the same or different from the content of the second ceramic material in the second ceramic coating region; and the third binder in the first ceramic coating region may be the same or different from the fourth binder in the second ceramic coating region; and / or the content of the third binder in the first ceramic coating region may be the same or different from the content of the fourth binder in the second ceramic coating region. Preferably, the first ceramic coating and the second ceramic coating have the same composition, that is, the first ceramic material in the first ceramic coating area is the same as the second ceramic material in the second ceramic coating area, and the content of the first ceramic material in the first ceramic coating area is the same as the content of the second ceramic material in the second ceramic coating area; and the third binder in the first ceramic coating area is the same as the fourth binder in the second ceramic coating area, and the content of the third binder in the first ceramic coating area is the same as the content of the fourth binder in the second ceramic coating area.

[0061] There are no particular restrictions on the first and second ceramic materials, and each can be independently selected from one or more of boehmite, alumina, silicon dioxide, and titanium dioxide, such as boehmite.

[0062] The third and fourth adhesives are not particularly limited and can be independently selected from one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), styrene-butadiene rubber (SBR), waterborne acrylic resins, and carboxymethyl cellulose (CMC), such as polyvinylidene fluoride (PVDF).

[0063] Figure 1 The structure of the positive electrode sheet of this invention is schematically shown, illustrating that on one surface of the positive electrode current collector, it comprises, from top to bottom, an empty foil region, a ceramic region, and a coating region (i.e., an active material coating region). The other surface of the positive electrode current collector is arranged in a similar manner.

[0064] Cylindrical battery cells

[0065] In a second aspect, this utility model relates to a cell for cylindrical batteries, comprising:

[0066] The positive electrode sheet according to the first aspect of this utility model;

[0067] Negative electrode; and

[0068] First diaphragm and second diaphragm;

[0069] The battery cell is wound into a jelly roll structure, and a first separator and a second separator separate the positive electrode and the negative electrode.

[0070] When viewed from the center outwards, the cell sequentially comprises a positive electrode, a first separator, a negative electrode, and a second separator.

[0071] After the battery cell is wound, it needs to be flattened. During the flattening process, metal debris will be generated, which can easily cause a short circuit between the positive and negative terminals of the core. In addition, if the separator is not properly covered, there is also a risk of a short circuit between the positive and negative terminals of the electrode or the tab, which can lead to battery failure.

[0072] The applicant discovered that when the positive electrode sheet according to the first aspect of the present invention is used in the battery cell, it can effectively reduce the short circuit between the positive and negative electrodes caused by poor diaphragm wrapping or metal debris during the core rolling process, thereby improving the safety performance of the battery; and the ceramic layer, to a certain extent, blocks the direct contact between the positive and negative electrode sheets, reducing the occurrence of fire and explosion after needle puncture.

[0073] Typically, a battery cell is formed by winding a positive electrode, a separator, and a negative electrode alternately, with the outermost layer being the separator. That is, the battery cell is formed by winding a positive electrode, a first separator, a negative electrode, and a second separator alternately, with the second separator as the outermost layer, followed by the negative electrode, then the first separator, and finally the positive electrode. The first and second separators cover and separate the positive and negative electrodes. Therefore, when viewed from the center of the battery cell outwards, the battery cell sequentially includes a positive electrode, a first separator, a negative electrode, and a second separator.

[0074] Figure 2 The structure of the cylindrical battery cell of this invention is schematically shown. For example... Figure 2 As shown, the battery cell includes a positive electrode sheet, a negative electrode sheet, a first separator, and a second separator, which are stacked and wound in the order of positive electrode sheet, first separator, negative electrode sheet, and second separator to form the battery core; the core may have a core through hole at the center, which is located at the center of the core interface and is used to discharge the gas generated during battery cycling.

[0075] Typically, the width of the positive electrode is no greater than the width of the negative electrode, the width of the negative electrode is no greater than the width of the first separator, and the width of the second separator is greater than the width of the negative electrode; let the width of the positive electrode be h. 正 (i.e., the width of the current collector), the width of the negative electrode is h. 负 The width of the first diaphragm is h1, and the width of the second diaphragm is h2; the width relationship is h1 / h2 / h2. 正 ≤h 负 ≤h1=h2; when h 正 and h 负When the difference is too large, although it is more beneficial for safety design, it will take up too much space, resulting in a decrease in energy density. 正 and h 负 The same value increases the probability of a short circuit; when 1.01 ≤ h 负 / h 正 ≤1.2 and h 负 When ≤h1=h2, it does not occupy too much space and will not reduce energy density; the electrode and diaphragm are set in this way to avoid short circuit inside the core caused by contact between the positive and negative electrode plates.

[0076] Figure 3 This schematically illustrates the dimensional and positional relationships of the positive electrode, first separator, negative electrode, and second separator in the thickness direction of a cylindrical battery cell of this invention in its unfolded state. Typically, the length L of the positive electrode is... 正 Length L of the negative electrode 负 The lengths L1 of the first diaphragm and L2 of the second diaphragm satisfy the relationship L 正 <L 负 <L1 = L2; the specific length relationship can be: L 正 <L 负 <L1 / 1.1 = L2 / 1.1; This design allows the negative electrode to cover the positive electrode, and the separator to cover the electrode. However, excessive redundancy leads to excessive space usage, reducing the overall energy density of the battery. Therefore, redundancy should not be too much; when the length ratio is L... 正 <L 负 / 1.05 < L1 / 1.1 = L2 / 1.1, indicating optimal battery safety design without significantly impacting space or energy density. During winding, the starting ends of the first and second separators are flush along their length. The positive electrode is furthest from the starting end of the separator, while the distance between the starting end of the negative electrode and the starting end of the separator is less than the distance between the starting end of the positive electrode and the starting end of the separator. At the end of the winding, the outermost separator covers the entire winding. The winding of the positive electrode is completed first, and since the negative electrode is slightly longer than the positive electrode, it can cover the positive electrode. The separator is the outermost layer and ends last, thus achieving complete coverage of the winding and ensuring insulation.

[0077] Figure 4-11 The diagrams schematically show views of cylindrical battery cells with different configurations in their unfolded state in the width (i.e., height) and thickness directions, showing the width, length, and positional relationship between the positive electrode, negative electrode, first separator, and second separator. The positive electrode is completely enclosed by the first separator and is completely enclosed by the negative electrode through the first separator, while the negative electrode is completely enclosed by both the first and second separators.

[0078] Figure 4 and 5The diagrams schematically show one configuration of battery cell in its unfolded state along its width direction. Figure 4 ) and in the thickness direction ( Figure 5 The dimensions and positions of the positive electrode, the first separator, the negative electrode, and the second separator are as follows: the width of the positive electrode is smaller than that of the negative electrode, smaller than that of the first separator, and smaller than that of the second separator; the starting positions of the positive electrode, the negative electrode, the first separator, and the second separator are the same along their length (i.e., at...). Figure 4 All three electrodes (starting from the leftmost end line) are of the same length; during winding, the positive electrode sheet is on the innermost side, and the second separator is on the outermost side. The positive electrode sheet, negative electrode sheet, first separator, and second separator all end at the same position in the length direction. The starting positions of the positive electrode sheet, negative electrode sheet, first separator, and second separator in the width direction can be the same or different (i.e., in...). Figure 4 (In the width direction, it may or may not start from the bottommost line).

[0079] Figure 6 and 7 The diagrams schematically show one configuration of battery cell in its unfolded state along its width direction. Figure 6 ) and in the thickness direction ( Figure 7 The dimensions and positions of the positive electrode, the first separator, the negative electrode, and the second separator are as follows: the width of the positive electrode is smaller than that of the negative electrode, which is smaller than that of the first separator; the width of the first separator is equal to that of the second separator; and the starting positions of the positive electrode, the negative electrode, the first separator, and the second separator are the same along their length (i.e., at...). Figure 6 (All start from the leftmost end line); the length of the positive electrode is equal to the length of the negative electrode, less than the length of the first separator, and less than the length of the second separator; during winding, the positive electrode is at the innermost position, and the second separator is at the outermost position. In the length direction, the second separator ends last, and the first separator ends earlier than the second separator, and later than the positive and negative electrodes. The positive and negative electrodes end simultaneously. The starting positions of the positive electrode, negative electrode, first separator, and second separator in the width direction can be the same or different (i.e., in...). Figure 6 (In the width direction, it may or may not start from the bottommost line).

[0080] Figure 8 and 9 The diagrams schematically show one configuration of battery cell in its unfolded state along its width direction. Figure 8 ) and in the thickness direction ( Figure 9 The dimensions and positions of the positive electrode, the first separator, the negative electrode, and the second separator are schematically shown, indicating that the width of the positive electrode is smaller than that of the negative electrode, smaller than that of the first separator, and smaller than that of the second separator. The starting positions of the positive electrode, the negative electrode, and the first and second separators are the same along their length (i.e., at...). Figure 8In the length direction, all start from the leftmost end line. The length of the positive electrode is the same as the length of the negative electrode and is less than the length of the first separator. The length of the first separator is the same as the length of the second separator. During winding, the positive electrode sheet is on the innermost side, and the second separator is on the outermost side. In the length direction, the ending positions of the positive and negative electrode sheets are the same, and the ending positions of the first and second separators are the same, but the ending position of the positive and negative electrode sheets is earlier than the ending positions of the first and second separators. The starting positions of the positive electrode sheet, negative electrode sheet, first separator, and second separator in the width direction can be the same or different (i.e., in the width direction). Figure 8 (In the width direction, it may or may not start from the bottommost line).

[0081] Figure 10 and 11 The diagrams schematically show one configuration of battery cell in its unfolded state along its width direction. Figure 10 ) and in the thickness direction ( Figure 11 The dimensions and positions of the positive electrode sheet, the first separator, the negative electrode sheet, and the second separator are as follows: The first and second separators start at the same position along their length, earlier than the positive and negative electrode sheets, with the negative electrode sheet starting earlier than the positive electrode sheet; the positive electrode sheet is shorter than the negative electrode sheet, the negative electrode sheet is shorter than the first separator, and the first separator is shorter than the second separator; during winding, the positive electrode sheet is at the innermost position, and the second separator is at the outermost position; the width of the positive electrode sheet is less than the width of the negative electrode sheet, which is less than the width of the first separator, which is less than the width of the second separator; along their length, the positive electrode sheet ends earliest, and the negative electrode sheet ends later than the positive electrode sheet but earlier than the first and second separators, with the first and second separators ending at the same position. The starting positions of the positive electrode sheet, negative electrode sheet, first separator, and second separator along their width can be the same or different (i.e., in...). Figure 10 (In the width direction, it may or may not start from the bottommost line).

[0082] However, this invention is not limited to this and other configurations may be adopted.

[0083] Cylindrical battery

[0084] In a third aspect, this utility model relates to a cylindrical battery, which includes:

[0085] A cylindrical battery cell according to the second aspect of this utility model, disposed inside a cylindrical battery casing;

[0086] The cylindrical battery cell is configured such that the empty foil region (i.e., the first and second empty foil regions) of its positive electrode is close to the positive terminal, and the active material coating region (i.e., the first and second active material coating regions) of its positive electrode is close to the negative terminal.

[0087] For cylindrical batteries, the cells need to be flattened after winding. This flattening process generates metal debris, which can easily cause short circuits between the positive and negative electrodes. Secondly, if the separator is not properly wrapped, there is also a risk of short circuits between the positive and negative electrodes of the plates or tabs, leading to battery failure. When the cells according to the second aspect of this invention are used in cylindrical batteries, short circuits between the positive and negative electrodes caused by poor separator wrapping or metal debris can be avoided, improving battery safety. Furthermore, the ceramic layer, to a certain extent, blocks direct contact between the positive and negative electrodes, reducing the occurrence of fire and explosion after needle puncture.

[0088] There are no particular limitations on the cylindrical battery, and it can be, for example, a cylindrical lithium-ion battery or a cylindrical sodium-ion battery.

[0089] Figure 12 The structure of the cylindrical battery of this invention is schematically shown. (For example...) Figure 12 As shown, a cylindrical battery typically includes a cylindrical casing (e.g., a nickel-plated steel casing), a cell (i.e., a winding core), current collectors (e.g., positive and negative current collectors), a cap, insulating pads (e.g., inner and outer insulating pads), a safety valve (not shown), and other components. The cylindrical casing is one-way, meaning the bottom is closed and the top is open. The bottom forms the negative electrode of the cylindrical battery (i.e., the negative electrode connected to the electrode winding core). The current collectors are placed on the winding core, and then the current collectors are connected to the cap. The cap is mechanically pressed to form an integral connection with the cylindrical casing.

[0090] Example

[0091] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0092] Example 1

[0093] Positive electrode preparation:

[0094] Preparation of positive electrode slurry: The positive electrode layered oxide Na[Cu] is prepared... 0.22 Fe 0.3 Mn 0.48 O2(D) 50 =9.0μm, Shanxi Huana Copper Energy Technology Co., Ltd. The initial discharge capacity at 0.5C is 134mAh / g), conductive carbon black (Swiss Temi high conductive carbon black SUPERP), and polyvinylidene fluoride (PVDF5130 purchased from SOLVAY) were mixed at a weight ratio of 97:1.4:1.6. N-methylpyrrolidone was added, and the mixture was stirred evenly under vacuum to obtain a positive electrode slurry with a solid content of 72wt%.

[0095] Preparation of ceramic slurry: Boehmite (from Anhui Yishitong Materials Technology Co., Ltd., model BG-613, D90 < 5μm, specific surface area 2-6m²) was used. 2 The powder was obtained by mixing polyvinylidene fluoride (PVDF5130 purchased from SOLVAY) and N-methylpyrrolidone (at a weight ratio of 1.7:1 to the powder) at a weight ratio of 8:2. The mixture was stirred and mixed evenly to obtain a ceramic slurry.

[0096] Preparation of the positive electrode: An aluminum foil with a length of 3000 mm, a width of 265 mm, and a thickness of 12 μm was selected. Then, a coating machine was used to coat the opposite surfaces of the aluminum foil as shown in the image. Figure 13 The coating process is as shown, followed by drying at 85°C and then rolling. The active material layer coated on both surfaces of the aluminum foil has a width of 249 mm and a thickness of 47 μm. Ceramic coatings are applied to both sides of the active material layer on both surfaces of the aluminum foil, with widths of 3 mm and thicknesses of 30 μm, and the width of the empty foil area on both sides is 5 mm. Then, a slitting process is performed, cutting the resulting positive electrode sheet along the central slitting line to form the following positive electrode sheet: length 3000 mm, width (h... 正 The width of the active material layer (D1 and D2) is 132.5 mm, the thickness of the active material layer (Dd1 and Dd2) is 47 μm, the width of the ceramic coating (C1 and C2) is 3 mm, the thickness of the ceramic coating (DC1 and DC2) is 30 μm, and the width of the empty foil area (B1 and B2) is 5 mm. Then it is dried under vacuum at 85 °C for 4 h.

[0097] Negative electrode preparation:

[0098] Hard carbon HNA104 (D) 50 =5.3μm, Shanxi Huana Carbon Energy Technology Co., Ltd. The initial discharge capacity at 0.5C is 375mAh / g), conductive carbon black Super P, sodium carboxymethyl cellulose, and styrene-butadiene rubber were mixed in a weight ratio of 94.0:1.8:1.5:2.7, deionized water was added, and a negative electrode slurry was obtained under vacuum stirring. The solid content of the negative electrode slurry was 54wt%. The negative electrode slurry was uniformly coated on both sides of an aluminum foil (12μm thick). The coated aluminum foil was dried at 85℃, and then cold-pressed, cut, and slit. After that, it was dried under vacuum at 85℃ for 12 hours to obtain the negative electrode sheet.

[0099] The negative electrode sheet is 134mm wide and 3090mm long, with a coating thickness of 68μm on both sides.

[0100] Electrolyte preparation:

[0101] 1 M sodium hexafluorophosphate (NaPF6) was dissolved in propylene carbonate (PC) / ethyl methyl carbonate (EMC) (volume ratio 1:1) to obtain a mixed solution. Then, 5 wt% ethylene sulfate (DTD) and 5 wt% fluoroethylene carbonate (FEC) relative to the total weight of the final electrolyte were added to the mixed solution and dispersed evenly to obtain the electrolyte.

[0102] diaphragm

[0103] The battery separator was XE20 (12μm thick, including a 9μm PE substrate and a 3μm ceramic coating) from Shenzhen Xuran Electronics Co., Ltd., with a length of 3200mm and a width of 131mm. Battery fabrication:

[0104] Preparation of sodium-ion batteries: Figure 3 As shown, the positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. The resulting cells are then wound to obtain a bare cell. The bare cell is flattened using a flattening machine to ensure the positive and negative terminal faces are smooth and burr-free. A short-circuit test is then performed on the flattened bare cell using a HiPot testing instrument. The positive and negative electrodes of the tested bare cell are then welded to the positive and negative busbars, respectively. The welded bare cell is placed in a 32140 cylindrical casing, and the prepared electrolyte is injected into the dried bare cell. Another short-circuit test is performed using a HiPot testing instrument. The tested cells then undergo sealing, settling, formation, and capacity testing processes to obtain a cylindrical sodium-ion battery.

[0105] One hundred batteries were prepared according to the above scheme and tested for 100 cycles at room temperature under 1C charge-discharge conditions within a voltage range of 2.0 to 3.8V.

[0106] Statistical analysis of test data from 100 batteries revealed that a total of 5 batteries experienced short circuits during various tests, resulting in a short circuit probability of 5%.

[0107] Example 2

[0108] 100 battery packs were prepared in the same manner as in Example 1, except that the width of the positive electrode active coating on both sides was changed to 124.85 mm and the width of the ceramic coating on both sides was changed to 2.65 mm when preparing the positive electrode sheet.

[0109] Statistical analysis of test data from 100 batteries revealed that a total of 8 batteries experienced short circuits during various tests, representing a short circuit probability of 8%.

[0110] Example 3

[0111] 100 sets of batteries were prepared in the same manner as in Example 1, except that the width of the positive electrode active coating on both sides was changed to 121 mm and the width of the ceramic coating on both sides was changed to 6.5 mm when preparing the positive electrode sheet.

[0112] Statistical analysis of test data from 100 batteries revealed that a total of 3 batteries experienced short circuits during various tests, resulting in a short circuit probability of 3%.

[0113] Comparative Example 1

[0114] 100 sets of batteries were prepared in the same manner as in Example 1, except that: when preparing the positive electrode, no ceramic coating was applied to either side and no empty foil area was provided.

[0115] The test showed that 30 batteries short-circuited, representing a 30% probability of short circuit.

[0116] Example 4

[0117] 100 battery packs were manufactured in the same manner as in Example 1, except that the thickness of the positive electrode active material layers on both sides was changed to 60 μm and the thickness of the ceramic coating on both sides was changed to 30 μm.

[0118] Ten batteries were found to have short-circuited during testing, representing a 10% probability of a short circuit.

[0119] Example 5

[0120] 100 sets of batteries were prepared in the same manner as in Example 1, except that the thickness of the positive electrode active material layers on both sides was changed to 35 μm and the thickness of the ceramic coating on both sides was changed to 30 μm.

[0121] Two batteries were found to have short-circuited during testing, representing a 2% probability of a short circuit.

[0122] The results above show that when empty foil areas and ceramic layers with specific width and thickness ratios are set on both sides of the positive electrode, the probability of short circuit in the battery can be significantly reduced.

[0123] The above description is merely an exemplary embodiment of this utility model. It should be noted that those skilled in the art can make improvements to this utility model without departing from its inventive concept, and all such improvements fall within the protection scope of this utility model.

Claims

1. A positive electrode plate, characterized in that, It includes a current collector, which has a first surface and a second surface in its thickness direction and a first end edge and a second end edge in its width direction. On the first surface, in the width direction from the first end edge to the second end edge, the current collector has, sequentially disposed, a first active material coating area, a first ceramic coating area adjacent to the first active material coating area, and a first empty foil area adjacent to the first ceramic coating area without any coating. On the second surface, a second active material coating area, a second ceramic coating area adjacent to the second active material coating area, and a second empty foil area adjacent to the second ceramic coating area without any coating are sequentially disposed. The widths of the first ceramic coating region and the first active material coating region are C1 and D1, respectively, where C1 / D1 = 0.02-0.

06. The widths of the second ceramic coating region and the second active material coating region are C2 and D2, respectively, where C2 / D2 = 0.02-0.

06. The ceramic coating thickness of the first ceramic coating region is Dc1, the active material coating thickness of the first active material coating region is Dd1, the ceramic coating thickness of the second ceramic coating region is Dc2, and the active material coating thickness of the second active material coating region is Dd2. The ratios of Dc1 / Dd1 and Dc2 / Dd2 are each independently 0.50-0.

86.

2. The positive electrode sheet as described in claim 1, characterized in that, C1 = C2, D1 = D2, Dc1 = Dc2, and Dd1 = Dd2.

3. The positive electrode sheet as described in any one of claims 1-2, characterized in that, (Dc1+Dc2) / (Dd1+Dd2+d1)=0.50-0.60, where d1 is the thickness of the positive current collector.

4. The positive electrode sheet according to any one of claims 1-2, characterized in that, The thickness of the positive electrode current collector is d1 = 5-50 μm, and the thickness of the first positive electrode active material layer Dd1 and the thickness of the second positive electrode active material layer Dd2 are each 10-100 μm independently.

5. The positive electrode sheet according to any one of claims 1-2, characterized in that, The width B1 of the first empty foil area and the width B2 of the second empty foil area may be the same or different.

6. The positive electrode sheet as described in claim 5, characterized in that, B1 / D1 and B2 / D2 are each independently between 0.01 and 0.

06.

7. The positive electrode sheet according to any one of claims 1-2, characterized in that, The positive electrode is a positive electrode for lithium-ion batteries or a positive electrode for sodium-ion batteries.

8. A cylindrical battery cell, characterized in that, It includes: The positive electrode sheet as described in any one of claims 1-7; Negative electrode plate; and First diaphragm and second diaphragm; The battery cell is wound into a jelly roll structure, and a first separator and a second separator separate the positive electrode and the negative electrode. When viewed from the center outwards, the cell sequentially comprises a positive electrode, a first separator, a negative electrode, and a second separator.

9. The cylindrical battery cell as described in claim 8, characterized in that, The width h of the positive electrode 正 The width h of the negative electrode 负 The widths h1 of the first diaphragm and h2 of the second diaphragm satisfy 1.01 ≤ h 负 / h 正 ≤1.2 and h 负 ≤h1=h2.

10. The cylindrical battery cell according to any one of claims 8-9, characterized in that, The length L of the positive electrode 正 Length L of the negative electrode 负 The lengths L1 of the first diaphragm and L2 of the second diaphragm satisfy the relationship L 正 <L 负 / 1.05<L1 / 1.1=L2 / 1.

1.

11. A cylindrical battery, characterized in that, It includes: A cylindrical battery cell as described in any one of claims 8-10, disposed within a cylindrical battery casing; The cylindrical battery cell is configured such that the empty foil area of ​​its positive electrode is close to the positive terminal, and the active material coating area of ​​its positive electrode is close to the negative terminal.

Images