Negative electrode plates, electrode assemblies, batteries and power consumption devices

Abstract

The present application discloses a negative electrode plate, an electrode assembly, a battery, and a power consumption device, in which a coating is provided on an edge of the negative electrode plate, the coating including a functional compound, which can react with sodium metal or lithium metal to generate gas.

Description

[Technical Field]

[0001] This application belongs to the field of secondary batteries and specifically relates to negative electrode plates, electrode assemblies, batteries, and power consumption devices. [Background technology]

[0002] Rechargeable batteries are widely used in various consumer electronic products and electric vehicles due to their excellent characteristics such as being lightweight, non-polluting, and having no storage effect. However, during the battery cycle, metal ions accumulate on the surface of the negative electrode plate, forming dendrites. In the later stages of the cycle, these dendrites can pierce the separator, posing a safety risk by causing a short circuit in the battery. [Overview of the project]

[0003] In light of the technical problems present in the background technology, this application provides a negative electrode plate that aims to avoid the risk that conventional batteries may cause a short circuit by generating dendrites on the negative electrode plate in the later stages of the cycle, which can pierce the separator.

[0004] To achieve the above objective, a first aspect of this application provides a negative electrode plate, the edge of which is provided with a coating, the coating comprising a functional compound, the functional compound being capable of reacting with a sodium metal or a lithium metal to generate a gas.

[0005] Compared with the prior art, the present application includes at least the following beneficial effects. The present application installs a coating containing a functional compound capable of reacting with sodium metal or lithium metal to generate gas at the edge of the negative electrode plate. As a result, in the later stage of the cycle, the tendency for dendrites to grow and extend parallel to the surface of the negative electrode plate is greater than the tendency for dendrites to grow along the thickness direction of the negative electrode plate, i.e., along the tip. When the dendrites growing parallel to the surface of the negative electrode plate extend to the coating, these dendrites contact the coating and react with the functional compound therein to generate gas, opening the explosion-proof valve, thereby avoiding the risk that the dendrites pierce through the separator and cause a short circuit in the battery.

[0006] In any embodiment of the present application, the functional compound includes at least one of an alcohol-based compound, a carboxylic acid-based compound, a phenol-based compound, an amine-based compound, a thiol-based compound, a benzophenone-based compound, and a cycloolefin-based compound. Thereby, in the later stage of the battery cycle, when the dendrites growing parallel to the surface of the negative electrode plate extend to the coating, these dendrites contact and react with such functional compounds in the coating, generate gas, and open the explosion-proof valve, thereby avoiding the risk that the dendrites pierce through the separator and cause a short circuit in the battery.

[0007] In any embodiment of the present application, the number of carbon atoms in the main chain of the functional compound is 4 or more, preferably 4 to 12.

[0008] In any embodiment of the present application, the mass ratio of the functional compound in the coating is 70% to 90%. Thereby, in the later stage of the battery cycle, when the dendrites growing parallel to the surface of the negative electrode plate extend to the coating, these dendrites contact and react with the functional compounds in the coating, generate gas, and open the explosion-proof valve, thereby avoiding the risk that the dendrites pierce through the separator and cause a short circuit in the battery.

[0009] In any embodiment of this application, the thickness of the coating is 5 μm to 60 μm. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery by reacting with the functional compound in the coating when dendrites grow parallel to the surface of the negative electrode plate in the later stages of the battery cycle, generating a gas that opens an explosion-proof valve.

[0010] In any embodiment of this application, the width of the coating is 3 mm or more, preferably 3 mm to 6 mm. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery by reacting with the functional compound in the coating when dendrites grow parallel to the surface of the negative electrode plate in the later stages of the battery cycle, generating a gas that opens an explosion-proof valve.

[0011] In any embodiment of this application, the coating extends to form an annular shape along the outer circumference of the negative electrode plate. This avoids the risk of the dendrites piercing the separator and causing a short circuit in the battery when, later in the battery cycle, dendrites growing parallel to the surface of the negative electrode plate extend to the coating, come into contact with and react with the functional compounds in the coating, generating a gas that opens an explosion-proof valve.

[0012] In any embodiment of this application, the coating is provided on opposing sides of the negative electrode plate in the width direction.

[0013] In any embodiment of this application, the negative electrode plate includes a negative electrode current collector, and the coating is provided on the edge of the negative electrode current collector.

[0014] In any embodiment of this application, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is provided on at least one side of the negative electrode current collector, and the coating is provided on the edge of the negative electrode active material layer.

[0015] A second aspect of this application provides an electrode assembly comprising a positive electrode plate, a negative electrode plate, and a separator, wherein the separator is provided between the positive electrode plate and the negative electrode plate, and the negative electrode plate includes the negative electrode plate described in the first aspect of this application. Thus, the electrode assembly has relatively high safety performance during the charge-discharge cycle process.

[0016] In any embodiment of this application, the orthographic projection of the coating on the negative electrode plate onto the positive electrode plate is located on the outside of the positive electrode plate.

[0017] In any embodiment of this application, a ceramic coating is provided on the longitudinal end of the positive electrode plate. This provides insulation, preventing burrs formed during the cutting process of the positive electrode plate from piercing the separator and forming a minute short circuit, while also preventing dendrites generated on the negative electrode plate from crossing the edge of the negative electrode plate and coming into contact with the positive electrode plate, thereby forming a minute short circuit.

[0018] A third aspect of this application provides a battery comprising the electrode assembly described in the second aspect of this application, thereby providing a relatively high level of safety performance.

[0019] A fourth aspect of this application provides a power consumption device, which includes a battery as described in the third aspect of this application, and which is used to provide electrical energy.

[0020] Additional aspects and advantages of this application are partially shown in the following description, partially evident from the following description, or understood through the practice of this application. [Brief explanation of the drawing]

[0021] To more clearly explain the technical concept of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort. [Figure 1] This is a schematic diagram of the structure of a negative electrode plate according to one embodiment of this application. [Figure 2] This is a schematic diagram of the structure of the negative electrode plate in another embodiment of this application. [Figure 3] This is a schematic diagram of the structure of a negative electrode plate in yet another embodiment of the present application. [Figure 4] This is a schematic diagram of the structure of a negative electrode plate in yet another embodiment of the present application. [Figure 5] This is a schematic diagram of the structure of a negative electrode plate in yet another embodiment of the present application. [Figure 6] This is a schematic diagram of the structure of an electrode assembly according to one embodiment of this application. [Figure 7] This is a schematic diagram of the structure of a positive electrode plate according to one embodiment of this application. [Figure 8] This is a schematic diagram of the structure of a battery according to one embodiment of this application. [Figure 9] This is a schematic diagram of the structure of a battery module according to one embodiment of this application. [Figure 10] This is a schematic diagram of the structure of a battery pack according to one embodiment of this application. [Figure 11] Figure 10 is an exploded view. [Figure 12] This is a schematic diagram of one embodiment of a power consumption device that uses a battery as a power source. [Modes for carrying out the invention]

[0022] The present application will be further described below, linking the embodiments for carrying out the invention. It should be understood that these specific embodiments are used solely to illustrate the present application and are not intended to limit the scope of the present application.

[0023] For simplicity, only a few numerical ranges are specifically disclosed in this specification. However, any lower limit and any upper limit may be combined to form an unspecified range, and any lower limit and another lower limit may be combined to form an unspecified range, and similarly, any upper limit and any other upper limit may be combined to form an unspecified range. Furthermore, each point or individual numerical value disclosed individually may be combined with any other point or individual numerical value as a lower or upper limit, or combined with other lower or upper limits to form an unspecified range.

[0024] In this specification, unless otherwise specified, the term "or" is inclusive. That is, the phrase "A or B" means "A, B, or both A and B." More specifically, the conditions A is true (or exists) and B is false (or does not exist), the condition A is false (or does not exist) but B is true (or exists), and the condition both A and B are true (or exist) all satisfy "A or B."

[0025] In this specification, unless otherwise specified, "above" and "below" include the number of items, and "plural" in "one or more" means two and two or more.

[0026] Unless otherwise specified, the terms used in this application have the meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of each parameter mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods shown in the embodiments of this application).

[0027] In recent years, new energy vehicles have developed dramatically, and in the electric vehicle sector, batteries play an irreplaceable and crucial role as the power source for electric vehicles. As a core component of new energy vehicles, batteries have relatively high demands in terms of both safety and cycle life.

[0028] In the early stages of the battery cycle, dendrites are concentrated on a large surface area of ​​the negative electrode plate. Later in the cycle, dendrites that have formed on a large surface area of ​​the negative electrode plate can pierce the separator and cause a short circuit in the battery, thus posing a safety risk.

[0029] Based on the above considerations, in order to reduce the risk of dendrites generated on the negative electrode plate piercing the separator and causing a short circuit in the battery later in the battery cycle, a first aspect of this application provides a negative electrode plate, for example, referring to Figure 1, wherein the edge of the negative electrode plate 100 is provided with a coating 11, the coating 11 comprising a functional compound, the functional compound being capable of reacting with sodium metal or lithium metal to generate a gas.

[0030] It should be explained that, in this application, the "edge of the negative electrode plate 100" refers to the area on the negative electrode plate 100 that is not covered by the positive electrode plate after the electrode assembly is constructed by laminating the negative electrode plate 100, the separator, and the positive electrode plate, i.e., the area where the length and / or width of the negative electrode plate 100 exceeds that of the positive electrode plate.

[0031] In the early stages of the battery cycle, non-uniform deposition appears on the negative electrode plate, followed by the formation of dendrites on a broad surface of the negative electrode plate. As the battery cycle progresses, in the later stages of the cycle, the dendrites grow along their tips, which can pierce the separator and cause a short circuit in the battery. Because the anisotropy of dendrite growth is greater than the isotropy, in the later stages of the cycle, dendrites simultaneously grow along a direction parallel to the surface of the negative electrode plate, and the tendency for dendrites to grow along this direction is greater than the tendency for growth at the tip. This application describes how, by placing a coating 11 containing a functional compound that can react with sodium metal or lithium metal to generate gas on the edge of the negative electrode plate 100, the battery avoids the risk of dendrites piercing the separator and causing a short circuit in the battery later in the cycle, because the tendency of dendrites to grow parallel to the surface of the negative electrode plate 100 is greater than the tendency of their tips to grow. When dendrites growing parallel to the surface of the negative electrode plate 100 extend to the coating 11 of the negative electrode plate 100, these dendrites come into contact with the functional compound in the coating 11 and react, generating gas and opening an explosion-proof valve.

[0032] In some embodiments, the functional compound in the coating 11 includes at least one of an alcohol compound, a carboxylic acid compound, a phenolic compound, an amine compound, a thiol compound, a benzophenone compound, and a cycloolefin compound. Specifically, the hydroxyl groups on the alcohol compound, carboxylic acid compound, and phenolic compound react with dendrites, such as sodium dendrite or lithium dendrite, to generate hydrogen gas; the amino groups on the amine compound react with dendrites, such as sodium dendrite or lithium dendrite, to generate ammonia gas; the thiol groups on the thiol compound react with dendrites, such as sodium dendrite or lithium dendrite, to generate hydrogen gas; the benzophenone compound reacts with dendrites, such as sodium dendrite or lithium dendrite, to generate hydrogen gas; and the cycloolefin compound reacts with dendrites, such as sodium dendrite or lithium dendrite, to generate hydrogen gas. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery by allowing them to react with such functional compounds in the coating 11 during the later stages of the battery cycle, generating gas that opens the explosion-proof valve.

[0033] In some embodiments, the number of carbon atoms on the main chain of the functional compound in the coating 11 is 4 or more, for example 4-15, 5-14, 6-13, 7-12, 8-11, or 9-10, and in some other embodiments, the number of carbon atoms on the main chain of the functional compound is 4-12.

[0034] For example, alcohol compounds include, but are not limited to, n-butanol, 2-butanol, n-pentanol, isoamyl alcohol, 2-pentanol, n-hexanol, 2-hexanol, n-heptanol, 2-heptanol, decanol, butanediol, etc.; carboxylic acid compounds include, but are not limited to, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, etc.; amine compounds include, but are not limited to, butylamine, pentylamine, hexylamine, heptylamine, etc.; thiol compounds include, but are not limited to, n-butyl mercaptan, 1-pentyl mercaptan, n-hexyl mercaptan, 1-heptyl mercaptan, etc.; phenolic compounds include, but are not limited to, phenol, cresol, hydroquinone, etc.; benzophenone compounds include, but are not limited to, benzophenone, acetophenone, etc.; and cycloolefin compounds include, but are not limited to, cyclopentadiene, cyclobutadiene, etc.

[0035] In some embodiments, the mass percentage of the functional compound in the coating 11 is 70% to 90%, for example, 72% to 90%, 72% to 88%, 74% to 86%, 75% to 85%, 78% to 82%, 78% to 80%, etc. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery when, in the later stages of the battery cycle, dendrites growing parallel to the surface of the negative electrode plate 100 extend to the coating 11, come into contact with and react with the functional compound in the coating 11, generating sufficient gas to open the explosion-proof valve.

[0036] Furthermore, the coating 11 further includes an adhesive; that is, a slurry containing a functional compound and an adhesive is applied to the edge of the negative electrode plate 100, and after drying and solidification, a coating 11 containing the functional compound is formed on the edge of the negative electrode plate 100.

[0037] For example, the adhesive may be one or more of the following: styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0038] In some embodiments, the thickness of the coating 11 is 5 μm to 60 μm, for example, 7 μm to 58 μm, 10 μm to 55 μm, 12 μm to 53 μm, 15 μm to 50 μm, 17 μm to 48 μm, 20 μm to 45 μm, 22 μm to 43 μm, 25 μm to 40 μm, 27 μm to 38 μm, 30 μm to 35 μm, 30 μm to 32 μm, etc. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery by reacting with the functional compound in the coating 11 in the later stages of the battery cycle, generating sufficient gas to open the explosion-proof valve.

[0039] It should be explained that in this application, "the thickness of the coating 11" refers to the thickness of the coating 11 on one side of the negative electrode plate 100.

[0040] In some embodiments, the width of the coating 11 is 3 mm or more, for example, 3 mm to 10 mm, 4 mm to 9 mm, 5 mm to 8 mm, 6 mm to 7 mm, etc. In some other embodiments, the width of the coating 11 is 3 mm to 6 mm. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery by allowing them to come into contact with the functional compound in the coating 11 and react, generating enough gas to open the explosion-proof valve.

[0041] In some embodiments, referring to Figure 2, the coating 11 extends to form an annular shape along the outer circumference of the negative electrode plate 100. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery by reacting with the functional compounds in the coating in the later stages of the battery cycle, generating sufficient gas to open the explosion-proof valve.

[0042] In some embodiments, referring to Figure 3, the coating 11 is provided on opposing sides of the negative electrode plate 100 in the width direction. By providing the coating 11 on opposing sides of the negative electrode plate 100 in the width direction, the distance to reach both ends of the negative electrode plate 100 in the width direction is smaller than the distance to both ends of the length direction. Therefore, in the later stages of the battery cycle, dendrites growing parallel to the surface of the negative electrode plate 100 preferentially extend to the coating 11 at both ends of the negative electrode plate 100 in the width direction. These dendrites come into contact with and react with the functional compounds in the coating, generating sufficient gas to open the explosion-proof valve, thus avoiding the risk of the dendrites piercing the separator and causing a short circuit in the battery.

[0043] In some embodiments, referring to Figure 4, the negative electrode plate 100 includes a negative electrode current collector 12, and the coating 11 is provided on the edge of the negative electrode current collector 12. This prevents the risk of the dendrites piercing the separator and causing a short circuit in the battery when, later in the battery cycle, dendrites growing parallel to the surface of the negative electrode plate 100 extend to the coating 11 of the negative electrode plate 100, come into contact with and react with the functional compound in the coating, generating sufficient gas to open an explosion-proof valve.

[0044] It should be explained that in this application, the "edge of the negative electrode current collector 12" refers to the area on the negative electrode current collector 12 that is not covered by the positive electrode plate after the electrode assembly is constructed by stacking the negative electrode plate 100, the separator, and the positive electrode plate, i.e., the area where the length and / or width of the negative electrode current collector 12 exceeds the positive electrode plate.

[0045] In some embodiments, referring to Figure 5, the negative electrode plate 100 includes a negative electrode current collector 12 and a negative electrode active material layer 13, the negative electrode active material layer 13 is provided on at least one side of the negative electrode current collector 12, and the coating 11 is provided on the edge of the negative electrode active material layer 13.

[0046] It should be explained that, in this application, "the edge of the negative electrode active material layer 13" refers to the region of the negative electrode plate 100 on the negative electrode active material layer 13 that is not covered by the positive electrode plate after the electrode assembly is constructed by laminating the negative electrode plate 100, the separator, and the positive electrode plate, i.e., the region where the length and / or width of the negative electrode active material layer 13 exceeds that of the positive electrode plate.

[0047] For example, the negative electrode current collector 12 may be a conventional metal foil sheet or a composite current collector (for example, a composite current collector may be formed by placing a metal material on a polymer substrate). For example, the negative electrode current collector 12 may be made of copper foil.

[0048] The specific type of negative electrode active material in the negative electrode active material layer 13 is not limited, and known active materials available for battery negative electrodes in the art may be used, and those skilled in the art can select them according to their actual needs. For example, the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicon-based materials, and tin-based materials. The silicon-based material may include one or more of elemental silicon, silicon oxide (e.g., silicon suboxide), silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may include one or more of elemental tin, tin oxide, and tin alloy. All of these materials are commercially available.

[0049] In some embodiments, the negative electrode active material may include a silicon-based material in order to further improve the energy density of the battery.

[0050] The negative electrode active material layer 13 generally further selectively includes an adhesive, a conductive agent, and other selective additives.

[0051] For example, the conductive agent may include one or more of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0052] For example, the adhesive may contain one or more of the following: styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0053] For example, other selective additives may include thickeners, dispersants (e.g., sodium carboxymethylcellulose CMC-Na), and PTC thermistor materials.

[0054] A second aspect of this application provides an electrode assembly, referring to Figure 6, the electrode assembly 1000 includes a positive electrode plate 200, a negative electrode plate 100, and a separator 300, the separator 300 being provided between the positive electrode plate 200 and the negative electrode plate 100, and the negative electrode plate 100 including the negative electrode plate described in the first aspect of this application. Thus, the electrode assembly has relatively high safety performance during the charge-discharge cycle process.

[0055] In some embodiments, referring to Figure 6, the orthographic projection of the coating 11 on the negative electrode plate 100 onto the positive electrode plate 200 is located outside the positive electrode plate 200, i.e., the coating 11 is located in an area of ​​the negative electrode plate 100 that is not covered by the positive electrode plate. Thereafter, in the later stages of the cycle, the dendrites tend to grow parallel to the surface of the negative electrode plate 100 more than their tip growth tendency, so when a dendrite growing parallel to the surface of the negative electrode plate 100 extends to the coating 11 of the negative electrode plate 100, before the dendrite tip breaks through the separator and causes a short circuit in the battery, this dendrite comes into contact with and reacts with the functional compound in the coating 11, generating a gas that opens an explosion-proof valve, thereby avoiding the risk of the dendrite breaking through the separator and causing a short circuit in the battery.

[0056] In some embodiments, referring to Figure 7, a ceramic coating 21 is provided on the longitudinal end of the positive electrode plate 200. By providing the ceramic coating 21 on the longitudinal end of the positive electrode plate 200, an insulating effect is achieved, preventing burrs formed during the cutting process of the positive electrode plate 200 from piercing the separator and forming a minute short circuit, while preventing dendrites generated on the negative electrode plate 100 from crossing the edge of the negative electrode plate 100 and coming into contact with the positive electrode plate 200 and forming a minute short circuit.

[0057] Furthermore, the thickness of the ceramic layer 21 is 5 μm to 60 μm, for example, 7 μm to 58 μm, 10 μm to 55 μm, 12 μm to 53 μm, 15 μm to 50 μm, 17 μm to 48 μm, 20 μm to 45 μm, 22 μm to 43 μm, 25 μm to 40 μm, 27 μm to 38 μm, 30 μm to 35 μm, 30 μm to 32 μm, etc. This thickness of ceramic layer 21 prevents burrs formed during the cutting process of the positive electrode plate 200 from piercing the separator and forming a minute short circuit, and at the same time prevents dendrites generated on the negative electrode plate 100 from crossing the edge of the negative electrode plate 100 and coming into contact with the positive electrode plate 200 and forming a minute short circuit.

[0058] For example, the ceramic layer 21 may contain one or more of the following: boehmite (γ-AlOOH), aluminum oxide (A12O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon dioxide (SiO2), tin dioxide (SnO2), titanium oxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), nickel oxide (NiO), cerium oxide (CeO2), zirconium titanate (SrTiO3), barium titanate (BaTiO3), and magnesium fluoride (MgF2).

[0059] The positive electrode plate 200 generally includes a positive electrode current collector and a positive electrode active material layer installed on the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0060] The positive electrode current collector may be a conventional metal foil sheet or a composite current collector (a composite current collector may be formed by placing metal materials on a polymer substrate). For example, the positive electrode current collector may be made of aluminum foil.

[0061] The specific type of positive electrode active material is not limited, and any active material known in the art that can be used in battery positive electrodes may be used, and those skilled in the art can select it according to their actual needs.

[0062] For example, when the battery is a lithium-ion battery, as an example, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates having an olivine structure, and modified compounds thereof. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof. Examples of lithium-containing phosphates having an olivine structure may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and modified compounds thereof. These materials can all be commercially available.

[0063] For example, when the battery is a sodium-ion battery, as an example, the positive electrode active material may include, but is not limited to, at least one of layered transition metal oxides, polyanion compounds, and Prussian blue analogs.

[0064] Examples of the above-mentioned layered transition metal oxides include, for example, the following: Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 < x ≦ 0.33, 0 < h ≦ 0.24, 0 ≦ k ≦ 0.32, 0 < l ≦ 0.68, 0 ≦ m < 0.1, h + k + l + m = 1, 0 ≦ y < 0.2, and Na 0.67 Mn 0.7 Ni z M2 0.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, and Ba, 0 < z ≦ 0.1, Na a Li b Ni c Mn d Fe e O2, where 0.67 < a ≦ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0065] Examples of the above polyanion compound include, for example, the following: A 1 f M 3 g (PO4) i O j X 1 3-j , where A is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≦ 4, 0 < g ≦ 2, 1 ≦ i ≦ 3, 0 ≦ j ≦ 2, Na n M 4 PO4X 2 where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≦ 2, Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≦ 2, and 0 < q ≦ 2, Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≦ 4 and 0 ≦ t ≦ 3. For example, t is 0, 1, 1.5, 2, or 3.

[0066] Examples of the above Prussian blue analogs include, for example, the following: A u M 6 v [M 7 (CN)6] w ·xH2O, where A is one or more of H + , NH 4+ , an alkali metal cation, and an alkaline earth metal cation, and M 6 and M 7 are each independently one or more of transition metal cations, and 0 < u ≦ 2, 0 < v ≦ 1, 0 < w ≦ 1, 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , and Ra 2+ and one or more of M 6 and M 7 are each independently cations of one or more transition metal elements of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W.

[0067] The modified compound of each of the above materials may perform doping modification and / or surface coating modification on the material.

[0068] The positive electrode active material layer generally further selectively contains an adhesive, a conductive agent, and other selective auxiliaries.

[0069] As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers.

[0070] For example, the adhesive may contain one or more of the following: styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0071] A third aspect of this application provides a battery comprising the electrode assembly described in the second aspect of this application, thereby providing a relatively high level of safety performance.

[0072] The battery may contain an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte may contain an electrolyte salt and a solvent.

[0073] If the battery is a lithium-ion battery, the electrolyte salt may, for example, include one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0074] If the battery is a sodium-ion battery, for example, the electrolyte sodium salt includes at least one of sodium hexafluorophosphate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, and sodium bis(trifluoromethanesulfone)imide.

[0075] For example, the solvent may include one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0076] In some embodiments, the electrolyte further includes additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and further additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature performance.

[0077] The embodiments of this application are not particularly limited to the shape of the battery, which may be cylindrical, rectangular, or any other shape. Figure 8 shows a rectangular battery 1 as an example.

[0078] In some embodiments, the battery may include an casing. This casing is used to package a positive electrode plate, a negative electrode plate, and an electrolyte.

[0079] In some embodiments, the exterior may include a case and a cover plate. Here, the case may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates enclose and form a housing cavity. The case has an opening that communicates with the housing cavity, and the cover plate can cover the opening to seal the housing cavity.

[0080] The positive electrode plate, negative electrode plate, and separator may form an electrode assembly by a winding or lamination process. The electrode assembly is packaged in the housing cavity. The electrolyte may be a liquid electrolyte, which is impregnated into the electrode assembly. The number of electrode assemblies included in the battery may be one or more and can be adjusted according to the requirements.

[0081] In some embodiments, the battery casing may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case.

[0082] The battery casing may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and may include one or more of the following: polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0083] In some embodiments, the batteries may be assembled into battery modules, and the number of batteries included in a battery module may be multiple, with the specific number being adjusted according to the application and capacity of the battery module.

[0084] Figure 9 shows an example of a battery module 2. Referring to Figure 9, in the battery module 2, the multiple batteries 1 may be arranged sequentially along the longitudinal direction of the battery module 2. Of course, they may be arranged in any other manner. Furthermore, these multiple batteries 1 may be fixed in place with fasteners.

[0085] The battery module 2 may further include a housing having a housing space, in which a plurality of secondary batteries 1 are housed. In some embodiments, the battery modules may further be assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0086] Figures 10 and 11 show an example of a battery pack 3. Referring to Figures 10 and 11, the battery pack 3 may include a battery box and a plurality of battery modules 2 installed in the battery box. The battery box includes an upper housing 4 and a lower housing 5, the upper housing 4 covering the lower housing 5 and forming a sealed space for housing the battery modules 2. The plurality of battery modules 2 may be arranged in the battery box in any manner.

[0087] [Power consumption equipment] This application further provides a power consumption device, the power consumption device including the battery, the battery being used to provide electrical energy. Specifically, the battery may serve as a power source for the power consumption device, or as an energy storage unit for the power consumption device. The power consumption device may be, but is not limited to, mobile devices (e.g., mobile phones, laptop computers), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, or energy storage systems.

[0088] Figure 12 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0089] Other examples of power-consuming devices may include mobile phones, tablet computers, and laptop computers. These power-consuming devices generally require a thin profile and may use batteries as their power source.

[0090] To clarify the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application, the embodiments will be described in more detail below, linking them to the drawings. Clearly, the embodiments described are only some, and not all, embodiments of this application. The following description of at least one exemplary embodiment is for illustrative purposes only and does not in any way limit this application or its applications. All other embodiments that can be obtained by a person skilled in the art without creative effort based on the embodiments of this application are all within the scope of protection of this application.

[0091] I. Examples Example 1 1. Manufacturing of positive electrode plates A positive electrode slurry was prepared by thoroughly dissolving polyvinylidene fluoride adhesive in N-methylpyrrolidone, and then adding carbon black conductive agent and positive electrode active material Na4Fe3(PO4)2P2O7 and dispersing them uniformly (the mass ratio of polyvinylidene fluoride, carbon black conductive agent, and positive electrode active material Na4Fe3(PO4)2P2O7 was 10:10:80). The positive electrode slurry was then uniformly applied to two surfaces of aluminum foil, transferred to a vacuum drying box for complete drying, roll-pressed the resulting electrode plate, and finally punch-diced it to obtain a positive electrode plate.

[0092] 2. Manufacturing of the negative electrode plate A negative electrode slurry was obtained by uniformly mixing artificial graphite as the negative electrode active material, carbon black (Super P) as the conductive agent, and styrene-butadiene rubber (SBR) and sodium carboxymethylcellulose (CMC-Na) as adhesives in a mass ratio of 96.4:0.7:1.8:1.1 with an appropriate amount of deionized water as the solvent. The negative electrode slurry was applied to two surfaces of the copper foil of the negative electrode current collector, and after drying, a negative electrode active material layer was formed on the negative electrode current collector. Then, a slurry containing the functional compound n-butanol and the adhesive styrene-butadiene rubber (in a mass ratio of 80:20) was applied to the two opposing edges in the width direction of the negative electrode active material layer on both sides, and after drying, a coating with a width of 5 mm and a thickness of 20 μm was formed on the edges of the negative electrode active material layer to form a negative electrode plate.

[0093] 3. Separator The separator is made of polyethylene film.

[0094] 4. Manufacturing of electrolyte Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:70 to obtain an organic solvent. The electrolyte salt NaPF6, which had been thoroughly dried, was dissolved in the above mixed solvent to make the electrolyte salt concentration 1.0 mol / L. After homogeneous mixing, an electrolyte solution was obtained.

[0095] 5. Battery manufacturing The positive electrode plate, separator, and negative electrode plate are stacked in order (the positive projection of the coating on the negative electrode plate on the positive electrode plate is located on the outer circumference of the positive electrode plate, and the size of the separator and the negative electrode plate are equal), the separator is positioned between the positive and negative electrode plates to provide isolation, and the assembly is wound up to obtain the electrode assembly. The electrode assembly is placed in an outer casing, the manufactured electrolyte is injected into the dried sodium-ion battery, and the sodium-ion battery is obtained through vacuum packaging, settling, chemical conversion, and shaping processes.

[0096] The manufacturing methods for sodium-ion batteries in Examples 2 to 20 are the same as in Example 1, with the differences shown in Table 1.

[0097] [Table 1]

[0098] The manufacturing method for sodium-ion batteries in Examples 21 to 40 is the same as in Example 1, the only difference being that the negative electrode active material layer is not coated onto the negative electrode current collector; rather, a coating is formed on the opposing edges at both ends in the width direction on both sides of the negative electrode current collector, and the coating parameters are as shown in Table 2.

[0099] [Table 2]

[0100] The manufacturing method for the sodium-ion battery in Comparative Example 1 is the same as in Example 1, the only difference being that there is no coating on the edge of the negative electrode active material layer, and the positive electrode plate and the negative electrode plate are of equal size. The manufacturing method for the sodium-ion battery in Comparative Example 2 is the same as in Example 21, the only difference being that the negative electrode current collector does not have a coating on its edge, and the positive electrode plate and the negative electrode plate are of equal size.

[0101] 2. Battery performance testing The batteries of Examples 1-40 and Comparative Examples 1-2 were each charged at 25°C with a constant current at a multiplier of 1C to a voltage of 3.65V, then charged at a constant voltage of 3.65V with a current of 0.05C, and then discharged with a constant current at a multiplier of 1C to a voltage of 2.5V. This constituted one charge-discharge cycle, and this charge-discharge cycle was repeated. After 500 cycles, the gas generation rate of the battery (the average value of the gas generation rate after 500 cycles) was detected, and the ignition status of the battery when the internal pressure of the battery reached 0.65Mpa (the limit value for breaching the explosion-proof valve is 0.65Mpa) was observed. The relevant test results are shown in Table 3.

[0102] The test method for the gas generation rate of a battery includes the following:

[0103] (1) An already assembled battery was taken, fired, then electrolyte was injected, the battery injection hole was sealed, and after activation at room temperature, metal composite tape was welded to the positive and negative electrodes of the battery to obtain the activated battery to be measured.

[0104] (2) The battery insertion holes were sealed using OPP beige tape. Aluminum tape was welded to the positive electrode of the battery, and nickel tape was welded to the negative electrode. The aluminum tape was welded using an ultrasonic welding machine, and the nickel tape was welded using an internal resistance spot welding machine.

[0105] (3) The activated battery is fixed to the jig, and the battery metal composite tape is connected to the positive and negative electrodes of the charge / discharge device with a wire, the wire being 2.5 mm 2 The copper wire is bonded to one end of a metal tape with an alligator clip welded to it. The charging and discharging equipment is a sodium battery chemical formation test cabinet, and the charging and discharging equipment is placed in a dry workspace with a dew point of ≤5°C, humidity of ≤20RH%, and temperature of ≤28°C.

[0106] (4) Turn on the power, pre-charge the activated battery, and record the values ​​of the digital pressure gauge at each necessary point in time before and during charging. (5) Based on the values ​​of the digital pressure gauge recorded before and after charging, the internal pressure of the battery at each point in time (i.e., the internal pressure of the battery) was calculated to analyze the amount of gas generated by the battery, and the average value of the gas generation rate after 500 cycles was calculated.

[0107] [Table 3] TIFF0007893974000004.tif150168

[0108] As can be seen from the data in Table 3, after 500 cycles, gas generation of sodium-ion batteries in Examples 1-40 rateThe fact that this was clearly higher than in Comparative Examples 1-2 indicates that after 500 battery cycles, the dendrites that formed on the negative electrode plate reacted with the functional compound in the coating on the negative electrode plate edge to generate gas, and that no ignition occurred in the sodium-ion batteries of Examples 1-40 when the internal pressure reached 0.65 MPa, indicating that the explosion-proof valve had already opened before a short circuit occurred in the battery. In contrast, the batteries of Comparative Examples 1-2 had already ignited before the internal pressure reached 0.65 MPa, thus demonstrating that by adopting the negative electrode plate of this application, in the later stages of the battery cycle, when dendrites growing parallel to the surface of the negative electrode plate extend to the coating, these dendrites come into contact with such functional compound in the coating and react, generating gas and opening the explosion-proof valve, thereby avoiding the risk of the dendrites piercing the separator and causing a short circuit in the battery.

[0109] Finally, it should be noted that the above embodiments are merely illustrative of the technical concepts of this application and do not limit them. While the application has been described in detail with reference to the embodiments described above, those skilled in the art will understand that they may still modify the technical concepts described in the embodiments above, or replace some or all of their technical features with equivalent ones, but such modifications or replacements will not deviate the essence of the relevant technical concepts from the scope of the technical concepts in the embodiments of this application, and that they should all be included within the scope of the claims and specification of this application. In particular, unless there is a structural conflict, the technical features referred to in each embodiment may be combined in any manner. This application is not limited to the specific embodiments disclosed herein, but includes all technical concepts included within the claims. [Explanation of symbols]

[0110] 1000: Electrode assembly, 100: Negative electrode plate, 11: Coating, 12: Negative electrode current collector, 13: Negative electrode active material layer, 200: Positive electrode plate, 21: Ceramic layer, 300: Separator 1: Rechargeable battery, 2: Battery module, 3: Battery pack, 4: Upper casing, 5: Lower casing.

Claims

1. A negative electrode plate, wherein the edge of the negative electrode plate is provided with a coating, the coating contains a functional compound, and the functional compound can react with sodium metal or lithium metal to generate a gas.

2. The functional compound comprises at least one of the following: an alcohol compound, a carboxylic acid compound, a phenol compound, an amine compound, a thiol compound, a benzophenone compound, and a cycloolefin compound. The alcohol compound comprises n-butanol, 2-butanol, n-pentanol, isoamyl alcohol, 2-pentanol, n-hexanol, 2-hexanol, n-heptanol, 2-heptanol, decanol, and butanediol. The carboxylic acid compound comprises butyric acid, pentanoic acid, hexanoic acid, and heptanoic acid. The negative electrode plate according to claim 1, comprising an acid, wherein the amine compound comprises butylamine, pentylamine, hexylamine, and heptylamine, the thiol compound comprises n-butyl mercaptan, 1-pentyl mercaptan, n-hexyl mercaptan, and 1-heptyl mercaptan, the phenol compound comprises phenol, cresol, and hydroquinone, the benzophenone compound comprises benzophenone and acetophenone, and the cycloolefin compound comprises cyclopentadiene and cyclobutadiene.

3. The negative electrode plate according to claim 1, wherein the number of carbon atoms on the main chain of the functional compound is 4 or more.

4. The negative electrode plate according to claim 1, wherein the mass ratio of the functional compound in the coating is 70% to 90%.

5. The negative electrode plate according to claim 1, wherein the thickness of the coating is 5 μm to 60 μm.

6. The negative electrode plate according to claim 1, wherein the width of the coating is 3 mm or more.

7. The negative electrode plate according to claim 1, wherein the coating extends to form an annular shape along the outer circumference of the negative electrode plate.

8. The negative electrode plate according to claim 1, wherein the coating is provided on both opposing sides in the width direction of the negative electrode plate.

9. The negative electrode plate according to claim 1, wherein the negative electrode plate includes a negative electrode current collector, and the coating is provided on the edge of the negative electrode current collector.

10. The negative electrode plate according to claim 1, wherein the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is provided on at least one side of the negative electrode current collector, and the coating is provided on the edge of the negative electrode active material layer.

11. An electrode assembly comprising a positive electrode plate, a negative electrode plate, and a separator, wherein the separator is provided between the positive electrode plate and the negative electrode plate, and the negative electrode plate includes the negative electrode plate described in claim 1.

12. The electrode assembly according to claim 11, wherein the orthographic projection of the coating on the negative electrode plate onto the positive electrode plate is located outside the positive electrode plate.

13. The electrode assembly according to claim 11, wherein a ceramic coating is provided on the longitudinal end of the positive electrode plate.

14. A battery comprising the electrode assembly according to any one of claims 11 to 13.

15. A power consumption device comprising a battery as described in claim 14, wherein the battery is used to provide electrical energy.

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