Secondary battery and electrical device

Abstract

A secondary battery and an electrical device. The secondary battery comprises a positive electrode sheet, a negative electrode sheet, and a separator arranged between the negative electrode sheet and the positive electrode sheet, the separator comprises a base membrane and adhesive particles located on at least one side of the base membrane, and the compression deformation rate of the adhesive particles under the pressure of 5 MPa at normal temperature is smaller than or equal to 40%.

Description

Secondary batteries and electrical devices

[0001] Cross-references

[0002] This application refers to Chinese Patent Application No. 2024103812334, filed on March 29, 2024, entitled “Secondary Battery and Electrical Device,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to the technical field of secondary batteries, and in particular to a secondary battery and an electrical device. Background Art

[0004] In recent years, secondary batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0005] The improvement of battery capacity and energy density often comes at the expense of secondary battery cycle performance and safety performance. How to achieve the simultaneous improvement of the two is a technical problem that technicians in this field urgently need to solve.

[0006] Summary of the Invention

[0007] The present application has been made in view of the above-mentioned problems, and an object of the present application is to provide a secondary battery having high energy density, cyclability, and safety.

[0008] In a first aspect, the present application provides a secondary battery comprising a positive electrode sheet, a negative electrode sheet, and an isolation membrane disposed between the negative electrode sheet and the positive electrode sheet, wherein the isolation membrane comprises a base film and adhesive particles located on at least one side of the base film, wherein the compression deformation rate of the adhesive particles under a pressure of 5 MPa at room temperature is less than or equal to 40%.

[0009] The adhesive particles located between the base film and the electrode can use their own compression resistance to provide support between the base film and the electrode, reduce the extrusion and shrinkage inside the battery cell during the winding process, keep the gap between adjacent electrode pieces uniform, reduce the risk of excessive extrusion on the inside causing the minimum gap value to be too low, and cause the diaphragm to be punctured, thereby improving the cycle life and safety performance of the battery.

[0010] In any embodiment, based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film accounts for 10%-50%, and optionally 15%-20%.

[0011] Based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film accounts for a proportion within the above range, which can not only play an effective supporting role between the base film and the electrode, but also take into account the role of bonding and positioning, and can also reserve space for metal deposition on the electrode, thereby comprehensively improving the cycle life of the secondary battery.

[0012] In any embodiment, the average particle size D of the bonding particles satisfies: 1 μm≤D≤60 μm, optionally 10 μm≤D≤40 μm, and the unit is μm.

[0013] The average particle size D of the bonding particles within the above range can ensure that the minimum gap value of the secondary battery will not be too low, thereby reducing the risk of the diaphragm being easily punctured due to the lack of expansion space for the negative electrode and the lack of deposition space for the metal, and will not cause the disordered growth of metal in the space due to an excessively large gap value, thereby worsening the gas production and life of the battery.

[0014] In any embodiment, the average particle size D of the bonding particles satisfies: H≤D≤3H; the unit is μm, and H≤D≤2H is optional.

[0015] Where H = A / (C × ρ)

[0016] H is the theoretical deposition thickness of the negative electrode, in μm; A is the charge capacity per unit area of ​​the positive electrode of the secondary battery, in mAh / cm 2 ; C is the theoretical gram capacity of the metal corresponding to the active ions of the secondary battery, in mAh / g; ρ is the metal density corresponding to the active ions of the secondary battery, in g / cm 3 .

[0017] The average particle size D of the bonding particles can be adapted and designed according to different secondary battery systems. Controlling the average particle size D of the bonding particles to be between 1 and 3 times the theoretical deposition thickness of the negative electrode can not only make the negative electrode deposition morphology of the metal in the negative electrode-free battery slightly loose, but also reduce the disordered growth of the metal at the negative electrode, which is beneficial to improving the cycle life of the secondary battery.

[0018] In any embodiment, the bonding particles include a mixture or cross-linked product of a rubber material and a plastic material.

[0019] The above-mentioned bonding particles can provide low compression deformation and a certain bonding effect, thereby comprehensively improving the cycle stability of the secondary battery.

[0020] In any embodiment, the rubber material includes one or more of polybutadiene, nitrile rubber, and EPDM rubber.

[0021] In any embodiment, the end groups of the rubber material include one or more of hydroxyl groups, epoxy groups, isocyanate groups, and carboxyl groups.

[0022] The terminal groups mentioned above are easy to react with the functional groups in the plastic material to form cross-links, so that the bonding particles can simultaneously play the role of compression resistance and bonding, thereby comprehensively improving the cycle life of the secondary battery.

[0023] In any embodiment, the rubber material includes one or more of hydroxyl-terminated polybutadiene (HTPB), epoxy-terminated polybutadiene (ETPB), isocyanate-terminated polybutadiene liquid rubber (ITPB), hydroxyl-terminated liquid nitrile rubber (HTBN), carboxyl-terminated liquid nitrile rubber (CTBN), carboxyl liquid nitrile rubber (CLNBR), and EPDM rubber.

[0024] In any embodiment, the plastic includes one or more of polyamide and polyetheramine.

[0025] The above-mentioned plastic material is not easy to react with the metal material deposited on the negative electrode, which can further improve the cycle stability of the secondary battery.

[0026] In any embodiment, the mass ratio of the rubber to the plastic in the bonding particles is 3:2-4:1.

[0027] The mass ratio of the rubber to the plastic in the bonding particles within the above range can take into account both the compressive resistance and bonding properties of the separator, thereby comprehensively improving the cycle stability and safety of the secondary battery.

[0028] In any embodiment, the base film includes at least one of a polyethylene film, a polypropylene film, a non-woven fabric, a polyethylene terephthalate film, a polyvinylidene fluoride film, and a polyurethane film.

[0029] In any embodiment, the secondary battery includes a wound cell, and the minimum gap value G of the secondary battery is min Satisfaction: G min ≥H, the gap value is the distance between the convex surfaces of adjacent positive electrode sheets, where the convex surface refers to the side of the positive electrode sheet at the bending area of ​​the wound battery cell away from the winding needle, in μm;

[0030] Where H = A / (C × ρ)

[0031] H is the theoretical deposition thickness of the negative electrode, in μm; A is the charge capacity per unit area of ​​the positive electrode of the secondary battery, in mAh / cm 2 ; C is the theoretical gram capacity of the metal corresponding to the active ions of the secondary battery, in mAh / g; ρ is the metal density corresponding to the active ions of the secondary battery, in g / cm 3 .

[0032] The minimum gap value Gmin of the secondary battery is greater than or equal to the theoretical deposition thickness H of the negative electrode, which can significantly reduce the risk of the diaphragm being punctured and the performance drop during the secondary battery cycle, thereby improving the cycle life and safety performance of the secondary battery.

[0033] In any embodiment, H≤Gmin<3H.

[0034] The minimum value Gmin of the gap value of the secondary battery is within the above range, so that the metal deposited on the negative electrode has a suitable growth morphology, which is beneficial to improving the cycle life of the secondary battery.

[0035] In any embodiment, 10≤Gmin<60, in μm.

[0036] In any embodiment, the range of the gap value of the secondary battery is less than 10 μm.

[0037] In any embodiment, the secondary battery comprises a metal battery, optionally a battery without a negative electrode.

[0038] Compared to other secondary batteries, cathode-free secondary batteries can achieve higher energy density due to the lack of a pre-installed negative electrode active material layer. However, cathode-free secondary batteries have higher requirements for the uniformity of the gap between the electrode plates than other secondary batteries. The separator provided in the embodiments of the present application is particularly suitable for cathode-free batteries, providing suitable space for metal deposition, reducing the probability of dendrites piercing the separator, improving the battery's safety performance and cycle life, and achieving a secondary battery with both high energy density and safety performance.

[0039] In any embodiment, the secondary battery includes a cylindrical battery.

[0040] Compared to other wound cell structures, cylindrical batteries have smaller winding pins, a tighter core structure, and low friction inside the core, resulting in a larger difference in the gap between the inner and outer sides of the core. The separators provided in the embodiments of this application are particularly suitable for cylindrical battery structures, providing suitable space for metal deposition, reducing the probability of dendrites piercing the separator, and improving battery safety and cycle life.

[0041] A second aspect of the present application provides an electrical device comprising the secondary battery of the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a schematic diagram of a separator in a secondary battery according to an embodiment of the present application;

[0043] FIG2 is a partial schematic diagram of a cell in a secondary battery according to an embodiment of the present application;

[0044] FIG3 is a statistical diagram of gap value test results of secondary batteries according to an embodiment of the present application and a comparative example;

[0045] FIG4 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0046] FIG5 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG4 ;

[0047] FIG6 is a schematic diagram of a battery module according to an embodiment of the present application;

[0048] FIG7 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0049] FIG8 is an exploded view of the battery pack shown in FIG7 according to an embodiment of the present application;

[0050] FIG. 9 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0051] Explanation of the reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 cover plate; 6 separator; 61 base film; 62 adhesive particles. DETAILED DESCRIPTION

[0052] Below, the embodiments of the secondary battery and the electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0053] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0055] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0056] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0057] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0058] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0059] Separator membranes are commonly used materials in secondary batteries. As an important component of secondary batteries, they carry the important functions of isolating the positive and negative electrodes, porously adsorbing electrolytes, and forming ion pathways. The surface of the separator membrane is often coated with a resin film. The resin film is hot-pressed to bond the electrodes and the separator, which is beneficial for the relative fixation between the layers and prevents relative displacement between the positive and negative electrodes. However, the high-strength bond between the electrode and the separator means that there is insufficient space between the electrode and the separator to accommodate the expansion of the material and / or deposition on the electrode. Especially in batteries without negative electrodes, this will result in no space for metal to deposit at the negative electrode during the cycle, which tends to squeeze the separator membrane, further puncturing the separator membrane and causing a short circuit inside the battery, leading to safety issues.

[0060] [Secondary battery]

[0061] Based on this, the present application provides a secondary battery, comprising a positive electrode sheet, a negative electrode sheet, and an isolation membrane arranged between the negative electrode sheet and the positive electrode sheet, the isolation membrane comprising a base film and bonding particles located on at least one side of the base film, the bonding particles having a compression deformation rate of less than or equal to 40% under a pressure of 5 MPa at room temperature.

[0062] In some embodiments, as shown in FIG. 1 , a separator 6 in a secondary battery includes a base film 61 and adhesive particles 62 located on at least one side of the base film 61 .

[0063] The compression deformation rate of the bonding particles at room temperature under a pressure of 5 MPa can be tested by any known method in the art. As an example, the compression strength of the bonding particles is tested using the FT-803-5KG particle strength tester. Specifically: place the sample in the mold, fill the mold and clamp it, select the compression test mode, set the compression pressure to 5 MPa, press the start button, the controller will start to apply force and record the deformation; the force sensor records the measurement data and transmits the data to the controller for processing. After the test is completed, the maximum deformation of the bonding particles measured is divided by the particle size of the bonding particles before compression as the compression deformation rate of the bonding particles at room temperature under a pressure of 5 MPa. It can be understood that the sample used for testing here can be either the bonding particles or the partial isolation membrane coated with the bonding particles. Since the deformation rate in the pressure direction is mainly determined by the deformation rate of the bonding particles, the compression deformation rate of the bonding particles at room temperature under a pressure of 5 MPa can also be obtained by filling the mold with the isolation membrane coated with the bonding particles.

[0064] In some embodiments, the compression deformation rate of the bonding particles under a pressure of 5 MPa at room temperature can be selected as 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or any range therebetween.

[0065] It can be understood that the bonding particles can be located on the positive electrode plate side or the negative electrode plate side of the base film, or on both sides at the same time.

[0066] In the secondary battery of the prior art, during the winding process of the battery cell, as the number of winding layers increases, the stress on the inner side of the battery cell (the side close to the winding needle is the inner side) will continue to increase, causing the resin film on the surface of the diaphragm to be squeezed accordingly, and the gap value between adjacent pole pieces is reduced. The closer to the winding needle, the greater the stress, causing the gap value between adjacent pole pieces in the direction from the outside to the inside of the battery cell to show a downward trend. Although the average value of the gap value can meet the design requirements of the pole piece, the minimum value of the gap value is too low to provide space for the expansion of the material and / or the deposition of the metal, resulting in a decrease in battery performance, and even leaving serious safety hazards and causing safety problems. In the embodiment of the present application, the adhesive particles located between the base film and the pole piece can use their own compression resistance to provide support between the base film and the pole piece, reduce the extrusion and contraction of the inner side of the battery cell during the winding process of the battery cell, keep the gap value between adjacent pole pieces uniform, reduce the risk of excessive extrusion on the inner side causing the minimum gap value to be too low, and cause the diaphragm to be punctured, thereby improving the cycle life and safety performance of the battery.

[0067] In some embodiments, based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film accounts for 10%-50%, and optionally 15%-20%.

[0068] Based on the total area of ​​the base film, the total projected area ratio of the bonding particles on one side on the base film can be obtained by any known method in the art. As an example, the test is performed using a CCD camera. Specifically: a sample of the isolation film with a unit area of ​​3 cm × 3 cm is cut and placed under a CCD camera with a field of view set to 10 times. The number of bonding particles in the sample is recorded, and the total projected area of ​​the bonding particles (in π × D) is multiplied by the number of bonding particles. 2 / 4 as the projected area of ​​the bonding particles, where D is the average particle size of the bonding particles) divided by the total area of ​​the base film is taken as the proportion of the total projected area of ​​the bonding particles on one side of the base film on the base film.

[0069] In some embodiments, based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film may be selected to be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any numerical range therebetween.

[0070] Based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film accounts for a proportion within the above range, which can not only play an effective supporting role between the base film and the electrode, but also take into account the role of bonding and positioning, and can also reserve space for metal deposition on the electrode, thereby comprehensively improving the cycle life of the secondary battery.

[0071] In some embodiments, the average particle size D of the bonding particles satisfies: 1 μm≤D≤60 μm, optionally 10 μm≤D≤40 μm, in μm.

[0072] The average particle size D of the bonding particles can be measured and obtained using any method known in the art. As an example, a cross-section of the separator is observed using a scanning electron microscope, and the particle sizes of the bonding particles located on the surface are statistically analyzed using Image J software. The number average value is used as the average particle size D of the bonding particles.

[0073] In some embodiments, the average particle size D of the bonding particles may be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or any range therebetween.

[0074] The average particle size D of the bonding particles within the above range can ensure that the minimum gap value of the secondary battery will not be too low, thereby reducing the risk of the diaphragm being easily punctured due to the lack of expansion space for the negative electrode and the lack of deposition space for the metal, and will not cause the disordered growth of metal in the space due to the excessive gap value, thereby worsening the gas production and life of the battery.

[0075] In some embodiments, the average particle size D of the bonding particles satisfies: H≤D≤3H; the unit is μm, and H≤D≤2H is optional.

[0076] Where H = A / (C × ρ)

[0077] H is the theoretical deposition thickness of the negative electrode, in μm; A is the charge capacity per unit area of ​​the positive electrode of the secondary battery, in mAh / cm 2 ; C is the theoretical gram capacity of the metal corresponding to the active ions of the secondary battery, in mAh / g; ρ is the metal density corresponding to the active ions of the secondary battery, in g / cm 3 .

[0078] The charging capacity per unit area of ​​the positive electrode sheet of a secondary battery can be obtained by any known method in the art. As an example, the battery is allowed to stand for 30 minutes at 25°C, discharged to 1.5V at a constant current of 1C, allowed to stand for 5 minutes, and then charged to 3.65V at a constant current of 1C, and then charged at a constant voltage to a cut-off current of 0.05C. The capacity of the test cell is used as the charging capacity of the secondary battery, and the charging capacity is divided by the area of ​​the positive electrode sheet as the charging capacity per unit area of ​​the secondary battery positive electrode sheet. The charging capacity per unit area of ​​the secondary battery positive electrode sheet can also be calculated by a×b×c, where a is the surface density of the positive electrode film layer, in g / cm 2 , b is the mass ratio of the positive electrode active material in the positive electrode film layer, and c is the charge capacity in grams of the secondary battery, which is calculated by dividing the charge capacity of the secondary battery by the mass of the positive electrode active material in the secondary battery, and the unit is mAh / g.

[0079] It is understood that different secondary battery systems have different negative electrode theoretical deposition thicknesses H. In some embodiments, 10 μm ≤ H < 30 μm. In some embodiments, H can be selected from 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, or any range therebetween.

[0080] The average particle size D of the bonding particles can be adapted and designed according to different secondary battery systems. Controlling the average particle size D of the bonding particles to be between 1 and 2 times the theoretical deposition thickness of the negative electrode can not only make the negative electrode deposition morphology of the metal in the negative electrode-free battery slightly loose, but also reduce the disordered growth of the metal at the negative electrode, which is beneficial to improving the cycle life of the secondary battery.

[0081] In some embodiments, the bonding particles include a mixture or cross-linked product of a rubber material and a plastic material.

[0082] In some embodiments, the rubber material undergoes elastic deformation under the action of an external force. Compared with commonly used plastic materials, it has the characteristics of hard texture, high degree of curing, high cross-linking density, and high compression modulus, and can provide excellent pressure resistance for the bonded particles.

[0083] In some embodiments, the plastic material undergoes plastic deformation under the action of an external force and has a relatively high viscosity, which can provide a certain surface bonding force to the bonding particles and exert a bonding effect.

[0084] The above-mentioned bonding particles can provide low compression deformation and a certain bonding effect, thereby comprehensively improving the cycle stability of the secondary battery.

[0085] In some embodiments, the rubber material includes one or more of polybutadiene, nitrile rubber, and EPDM rubber.

[0086] In some embodiments, the end groups of the rubber material include one or more of hydroxyl groups, epoxy groups, isocyanate groups, and carboxyl groups.

[0087] The terminal groups mentioned above are easy to react with the functional groups in the plastic material to form cross-links, so that the bonding particles can simultaneously play the role of compression resistance and bonding, thereby comprehensively improving the cycle life of the secondary battery.

[0088] In some embodiments, the rubber material includes one or more of hydroxyl-terminated polybutadiene (HTPB), epoxy-terminated polybutadiene (ETPB), isocyanate-terminated polybutadiene liquid rubber (ITPB), hydroxyl-terminated liquid nitrile rubber (HTBN), carboxyl-terminated liquid nitrile rubber (CTBN), carboxyl liquid nitrile rubber (CLNBR), and EPDM rubber.

[0089] In some embodiments, the plastic includes one or more of polyamide and polyetheramine.

[0090] The above-mentioned plastic material is not easy to react with the metal material deposited on the negative electrode, which can further improve the cycle stability of the secondary battery.

[0091] In some embodiments, the mass ratio of the rubber to the plastic in the bonding particles is 3:2-4:1.

[0092] In some embodiments, the mass ratio of the rubber to the plastic in the bonding particles may be 3:2, 1:1, 2:1, 3:1, 4:1, or any range therebetween.

[0093] The mass ratio of the rubber to the plastic in the bonding particles within the above range can take into account both the compressive resistance and bonding properties of the separator, thereby comprehensively improving the cycle stability and safety of the secondary battery.

[0094] In some embodiments, the base film includes at least one of a polyethylene film, a polypropylene film, a non-woven fabric, a polyethylene terephthalate film, a polyvinylidene fluoride film, and a polyurethane film.

[0095] In some embodiments, the secondary battery includes a wound cell, and the minimum gap value G of the secondary battery is min Satisfaction: G min ≥H, the gap value is the distance between the convex surfaces of adjacent positive electrode sheets, where the convex surface refers to the side of the positive electrode sheet at the bending area of ​​the wound battery cell away from the winding needle, in μm;

[0096] Where H = A / (C × ρ)

[0097] H is the theoretical deposition thickness of the negative electrode, in μm; A is the charge capacity per unit area of ​​the positive electrode of the secondary battery, in mAh / cm 2 ; C is the theoretical gram capacity of the metal corresponding to the active ions of the secondary battery, in mAh / g; ρ is the metal density corresponding to the active ions of the secondary battery, in g / cm 3 .

[0098] The gap value of a secondary battery can be obtained by testing methods known in the art. As an example, as shown in Figure 2, a wound cell is scanned using computed tomography (CT), and the positions of the positive and negative electrode sheets are determined by the brightness in the image. Generally, the negative electrode sheet appears brighter in the CT image, while the positive electrode sheet appears lower in the CT image. The distance L1 between the convex surfaces of two adjacent positive electrode sheets is used as the gap value of the secondary battery. The convex surface refers to the side of the positive electrode sheet in the bend area of ​​the wound cell that is away from the winding needle. As shown in Figure 3, the gap value of the cell is tested by sampling horizontally from the inside to the outside. For wound cells, the inner side is subjected to greater stress. To improve test accuracy, the sampling position for the first test is from the innermost positive electrode convex surface to the fifth positive electrode convex surface. The distance value obtained by the test is divided by 4 as the gap value G of the first area (from the innermost positive electrode convex surface to the fifth positive electrode convex surface). After the 5th positive electrode convex surface, a sample is taken every 5 layers of positive electrode convex surface. The sampling position for the second test is from the 5th positive electrode convex surface to the 10th positive electrode convex surface. The distance value obtained by sampling is divided by 5 as the gap value of the second area (from the 5th positive electrode convex surface to the 10th positive electrode convex surface). Similarly, the sampling position for the third test is from the 10th positive electrode convex surface to the 15th positive electrode convex surface. The distance value obtained by sampling is divided by 5 as the gap value of the third area (from the 10th positive electrode convex surface to the 15th positive electrode convex surface). The outermost layer ends with the cathode convex surface. When the last sampling is less than 5 layers, the number of cathode layers x between the inner and outer layers is recorded. The distance obtained is divided by x as the gap value of the last area. The minimum value of the gap value G obtained by the test is taken as the minimum value Gmin of the gap value of the secondary battery.

[0099] The minimum gap value Gmin of the secondary battery is greater than or equal to the theoretical deposition thickness H of the negative electrode, which can significantly reduce the risk of the diaphragm being punctured and the performance drop during the secondary battery cycle, thereby improving the cycle life and safety performance of the secondary battery.

[0100] In some embodiments, H≤Gmin<3H.

[0101] The minimum value Gmin of the gap value of the secondary battery is within the above range, so that the metal deposited on the negative electrode has a suitable growth morphology, which is beneficial to improving the cycle life of the secondary battery.

[0102] In some embodiments, 10≤Gmin<60, in μm.

[0103] In some embodiments, Gmin can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or any range therebetween. In some embodiments, the range of the gap value of the secondary battery is less than 10 μm.

[0104] In some embodiments, the range of the gap value of the secondary battery can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or any range therebetween. The range of the gap value is calculated by subtracting the minimum gap value from the maximum gap value of the measured battery cell.

[0105] Secondary batteries with uniform gap values ​​can provide uniform space for metal deposition, reduce the probability of metal dendrites growing on the negative electrode piercing the diaphragm and causing internal short circuits in the secondary battery and waste of battery space, and significantly improve the safety performance and cycle life of the secondary battery.

[0106] In some embodiments, the secondary battery comprises a metal battery, optionally a battery without an anode.

[0107] Metal batteries refer to batteries that use metal materials as negative electrode active materials, including sodium metal batteries and lithium metal batteries as examples.

[0108] In some embodiments, the secondary battery comprises a negative electrode-free secondary battery, which may be a sodium negative electrode-free battery or a lithium negative electrode-free battery.

[0109] A negative electrode-free secondary battery refers to a battery that does not actively set a negative electrode active material layer on the negative electrode side during the battery manufacturing process. For example, a metal or carbonaceous active material layer is not set at the negative electrode through coating or deposition to form a negative electrode active material layer during the battery manufacturing process. During the first charge, the active ions on the anode side obtain electrons and are deposited on the surface of the current collector in the form of metal to form a metal phase. During discharge, the metal can be converted into active ions and return to the positive electrode, realizing cyclic charge and discharge. Therefore, a negative electrode-free secondary battery is also a metal battery. Compared with other secondary batteries, a negative electrode-free secondary battery can achieve higher energy density because there is no pre-set negative electrode active material layer.

[0110] In some embodiments, to improve battery performance, the negative electrode side of a negative electrode-free secondary battery may be provided with some conventional negative electrode active materials, such as carbonaceous materials, metal oxides, alloys, etc. Although these materials have a certain capacity, due to the small amount of these materials, they are not used as the main negative electrode active materials in the battery and are therefore not considered to form a negative electrode active material layer that plays a role in the embedding of active ions. The secondary battery thus constructed can still be considered a negative electrode-free secondary battery.

[0111] In some embodiments, the CB value of the negative electrode-free secondary battery is less than or equal to 0.1.

[0112] The CB value is the capacity per unit area of ​​the negative electrode in a secondary battery divided by the capacity per unit area of ​​the positive electrode. Since a battery without a negative electrode contains no or only a small amount of negative electrode active material, the capacity per unit area of ​​the negative electrode is relatively small, and the CB value of a secondary battery is less than or equal to 0.1.

[0113] In cathode-free secondary batteries, metal deposited during cycling serves as the negative electrode active material. Compared to other secondary batteries, this requires a more uniform gap between electrode plates. The separators provided in the embodiments of this application are particularly suitable for cathode-free batteries, providing suitable space for metal deposition, reducing the probability of dendrites piercing the separator, and improving battery safety and cycle life.

[0114] In some embodiments, the secondary battery includes a cylindrical battery.

[0115] Compared to other wound cell structures, cylindrical batteries have smaller winding pins, a tighter core structure, and low friction inside the core, resulting in a larger difference in the gap between the inner and outer sides of the core. The separators provided in the embodiments of this application are particularly suitable for cylindrical battery structures, providing suitable space for metal deposition, reducing the probability of dendrites piercing the separator, and improving battery safety and cycle life.

[0116] [Positive electrode]

[0117] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, a conductive agent and a binder in some embodiments or a binder prepared by the preparation method in some embodiments.

[0118] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0119] In some embodiments, the positive active material may include at least one of a layered oxide, a polyanionic compound, and a Prussian blue-based compound.

[0120] Polyanionic compounds can be metal ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. The metal ion can be selected from sodium ion, lithium ion, potassium ion, and zinc ion; the transition metal can be selected from at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be selected from at least one of P, S, and Si; n represents (YO4) n- valence.

[0121] Prussian blue compounds can be compounds containing sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds are, for example, Na a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0122] The positive electrode film layer may further include a conductive agent to improve the conductivity of the positive electrode. The conductive agent may be selected from one or more of Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0123] The positive electrode film layer may further include a binder to firmly bond the positive electrode active material and optional conductive agent to the positive electrode current collector. The binder may be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0124] The positive electrode current collector can be a conductive carbon sheet, metal foil, carbon-coated metal foil, porous metal plate, or a composite current collector. The conductive carbon material of the conductive carbon sheet can be selected from one or more of Super P, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, carbon-coated metal foil, and porous metal plate can each be independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector can be a composite of metal foil and a polymer-based film.

[0125] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0126] [Negative electrode]

[0127] In some embodiments, a secondary battery includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector, and the negative electrode current collector optionally includes at least one of copper foil and aluminum foil.

[0128] In some embodiments, the negative electrode sheet includes a primer layer formed on a surface of the negative electrode current collector.

[0129] In some embodiments, the primer layer comprises at least one of superconductive carbon black, Ketjen black, acetylene black, carbon nanotubes, and graphene.

[0130] In some embodiments, the surface density of the primer layer is 5 to 50 g / m 2 .

[0131] In some embodiments, the surface density of the primer layer may be 5 to 10 g / m 2 , 5~20g / m 2 , 5~30g / m 2 , 5~40g / m 2 , 5~50g / m 2 , 10~20g / m 2 , 10~30g / m 2 、 10~40g / m 2 , 10~50g / m 2 , 20~30g / m 2 , 20~40g / m 2 , 20~50g / m 2 30~40g / m 2 30~50g / m 2 , 40~50g / m 2 Any one of .

[0132] The above-mentioned primer layer can induce ion deposition, effectively improving the energy density and cycle retention rate of the battery and meeting the battery usage requirements.

[0133] In some embodiments, the negative electrode plate comprises at least one of copper foil, gravure aluminum foil, multi-walled carbon nanotube or single-walled carbon nanotube-primed aluminum foil.

[0134] [Electrolytes]

[0135] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0136] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0137] In some embodiments, the electrolyte salt may be selected from at least one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, sodium perchlorate, and sodium chloride.

[0138] In some embodiments, the electrolyte comprises an ester solvent, and the ester solvent comprises at least one selected from ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, and fluoroethylene carbonate.

[0139] In some embodiments, the electrolyte contains an ether solvent, and the ether solvent includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether, and optionally includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.

[0140] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0141] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0142] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0143] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape. For example, FIG4 shows a secondary battery 5 with a square structure as an example.

[0144] In some embodiments, referring to Figure 5, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0145] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0146] Figure 6 shows an example battery module 4. Referring to Figure 6 , within the battery module 4, multiple secondary batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple secondary batteries 5 may be secured using fasteners.

[0147] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0148] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0149] Figures 7 and 8 illustrate an example battery pack 1. Referring to Figures 7 and 8 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0150] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0151] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0152] Figure 9 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0153] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0154] Example

[0155] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0156] 1. Preparation method

[0157] Example 1

[0158] 1) Preparation of bonding particles

[0159] Polyamide was added to an epoxy-terminated polydibutylene liquid rubber material, with a mass ratio of 4:1. After vacuum degassing, the material was cured at 120°C for 12 hours. The product was extruded through a disc pelletizer to obtain bonded particles with an average particle size of 15 μm. The bonded particles had a compression set of 5% under a pressure of 5 MPa at room temperature, and an average particle size D of 15 μm.

[0160] 2) Preparation of isolation membrane

[0161] The adhesive particles are dispersed in water to form a suspension, and then transferred to the base film through a spraying process. The spraying amount is controlled so that the total projected area of ​​the adhesive particles on one side of the base film accounts for 20% of the total area of ​​the base film; the base film is a polyethylene film.

[0162] 3) Preparation of positive electrode sheet

[0163] A uniformly dispersed positive electrode slurry is prepared by fully dissolving 2wt% polyvinylidene fluoride binder in N-methylpyrrolidone, adding 3wt% carbon black conductive agent and 95wt% sodium ferric pyrophosphate, the positive electrode active material. The positive electrode slurry is evenly coated on the surface of aluminum foil and then transferred to a vacuum drying oven for complete drying. The resulting electrode sheet is then roll-pressed and punched to obtain the positive electrode sheet.

[0164] 4) Preparation of negative electrode sheet

[0165] Add carbon nanotubes and sodium alginate into deionized water and stir to form a uniform slurry, apply the slurry on the negative electrode current collector, dry to obtain a primer layer, and cut to obtain a negative electrode sheet without a negative electrode structure.

[0166] 5) Preparation of electrolyte

[0167] A mixed solvent of ethylene glycol dimethyl ether (DME) and diethylene glycol diethyl ether (DEE) was prepared in a 1:1 volume ratio. In an argon atmosphere glove box (H₂O content <10 ppm, O₂ content <1 ppm), sodium hexafluorophosphate (NaPF₆) was dissolved in the mixed solvent and stirred to obtain an electrolyte solution with a sodium salt concentration of 1 mol / L.

[0168] 6) Battery preparation

[0169] The positive electrode sheet, composite isolation membrane, and negative electrode sheet are stacked in order, with the isolation membrane placed between the positive and negative electrodes to play an isolating role, and then wound. The bare battery cell is placed in the outer packaging, injected with the prepared electrolyte, and packaged, injected, formed, and vented. The process obtains a negative electrode-free sodium cylindrical battery.

[0170] The corresponding parameters were adjusted in Examples 2-10, as shown in Table 1.

[0171] Comparative Example 1 is basically the same as Example 1, except that polyvinylidene fluoride (PVDF) resin particles are sprayed on the surface of the base film, the average particle size of which is 25 μm and the spraying area accounts for 20%.

[0172] Table 1

[0173] 2. Performance Testing

[0174] 1. Cycle capacity retention test

[0175] The battery was left at rest for 30 minutes at 25°C, discharged at a constant current of 1C to 1.5V, left at rest for 5 minutes, then charged at a constant current of 1C to 3.65V, then charged at a constant voltage to a cutoff current of 0.05C, left at rest for 5 minutes, and discharged at a constant current of 1C to 1.5V. The test cell capacity was recorded as the initial capacity (C0). After leaving at rest for 5 minutes, the above steps were repeated for the same battery, and the number of cycles when the battery capacity retention rate decayed to 80% was recorded; the battery capacity retention rate Pn = Cn / C0×100%.

[0176] 3. Analysis of test results of various embodiments and comparative examples

[0177] Batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in Table 2.

[0178] Table 2

[0179] The surface density a of the secondary battery positive electrode sheet in the embodiment and the comparative example is 0.35g / 1540.25mm 2The mass content of the positive electrode active material based on the positive electrode film layer is 95%, and the charge capacity of the positive electrode active material is 115 mAh / g. The charge capacity per unit area of ​​the positive electrode sheet of the embodiment of the present application is calculated to be 2.5 mAh / cm 2 The theoretical gram capacity C of sodium metal is 1166 mAh / g; the density ρ of sodium metal is 0.968 g / cm 3 , the theoretical deposition thickness H of the negative electrode is calculated to be 20um.

[0180] From the comparison between the embodiment and the comparative example, it can be seen that the isolation membrane in the embodiment of the present application includes a base membrane and bonding particles located on at least one side of the base membrane, and the compression deformation rate of the bonding particles under a pressure of 5 MPa at room temperature is less than or equal to 40%, so that the minimum value of the secondary battery gap value will not be too low, thereby improving the cycle life of the secondary battery.

[0181] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present application, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery, characterized in that: It includes a positive electrode sheet, a negative electrode sheet and an isolation membrane arranged between the negative electrode sheet and the positive electrode sheet, the isolation membrane includes a base film and bonding particles located on at least one side of the base film, and the compression deformation rate of the bonding particles under a pressure of 5MPa at room temperature is less than or equal to 40%.

2. The secondary battery according to claim 1, wherein Based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film accounts for 10%-50%.

3. The secondary battery according to claim 1, wherein Based on the total area of ​​the base film, the total projected area of ​​the bonding particles on one side on the base film accounts for 15%-20%.

4. The secondary battery according to any one of claims 1 to 3, characterized in that The average particle size D of the bonding particles satisfies: 1 μm≤D≤60 μm, in μm.

5. The secondary battery according to any one of claims 1 to 3, characterized in that The average particle size D of the bonding particles satisfies: 10 μm≤D≤40 μm.

6. The secondary battery according to any one of claims 1 to 5, characterized in that The bonding particles include a mixture or a cross-linked product of a rubber material and a plastic material.

7. The secondary battery according to claim 6, characterized in that The rubber material includes one or more of polybutadiene, nitrile rubber, and EPDM rubber.

8. The secondary battery according to claim 6 or 7, characterized in that The end groups of the rubber material include one or more of hydroxyl groups, epoxy groups, isocyanate groups, and carboxyl groups.

9. The secondary battery according to any one of claims 6 to 8, characterized in that The rubber material includes one or more of hydroxyl-terminated polybutadiene (HTPB), epoxy-terminated polybutadiene (ETPB), isocyanate-terminated polybutadiene liquid rubber (ITPB), hydroxyl-terminated liquid nitrile rubber (HTBN), carboxyl-terminated liquid nitrile rubber (CTBN), carboxyl-terminated liquid nitrile rubber (CLNBR), and EPDM rubber.

10. The secondary battery according to any one of claims 6 to 9, characterized in that The plastic includes one or more of polyamide and polyetheramine.

11. The secondary battery according to any one of claims 6 to 10, characterized in that The mass ratio of the rubber to the plastic in the bonding particles is 3:2-4:

1.

12. The secondary battery according to any one of claims 1 to 11, characterized in that: The base film includes at least one of a polyethylene film, a polypropylene film, a non-woven fabric, a polyethylene terephthalate film, a polyvinylidene fluoride film, and a polyurethane film.

13. The secondary battery according to any one of claims 1 to 12, characterized in that: The secondary battery includes a wound battery cell, and the minimum gap value G of the secondary battery is min Satisfaction: G min ≥H, the gap value is the distance between the convex surfaces of adjacent positive electrode sheets, where the convex surface refers to the side of the positive electrode sheet at the bending area of ​​the wound battery cell away from the winding needle, in μm; Where H = A / (C × ρ) H is the theoretical deposition thickness of the negative electrode, in μm; A is the charge capacity per unit area of ​​the positive electrode of the secondary battery, in mAh / cm 2 ; C is the theoretical gram capacity of the metal corresponding to the active ions of the secondary battery, in mAh / g; ρ is the metal density corresponding to the active ions of the secondary battery, in g / cm 3 .

14. The secondary battery according to any one of claims 1 to 13, characterized in that H≤Gmin<3H.

15. The secondary battery according to any one of claims 1 to 13, characterized in that 10≤Gmin<60, unit is μm.

16. The secondary battery according to any one of claims 1 to 15, characterized in that The range of the gap value of the secondary battery is less than 10 μm.

17. The secondary battery according to any one of claims 1 to 16, characterized in that: The secondary battery includes a metal battery.

18. The secondary battery according to any one of claims 1 to 17, characterized in that The secondary battery includes a negative electrode-less battery.

19. The secondary battery according to any one of claims 1 to 18, characterized in that The secondary battery includes a cylindrical battery.

20. An electrical device, characterized in that: The electric device includes the secondary battery according to any one of 1 to 19.

Images