Composite cell, secondary battery, and electric device

Abstract

The invention relates to a composite battery cell, a secondary battery and a power utilization device, the composite battery cell comprises a battery cell body and a current sensitive coating, the surface, adjacent to other battery cells, of the battery cell body is coated with the current sensitive coating, and the current sensitive coating comprises a current sensitive material; by arranging the current sensitive coating containing the current sensitive material, when the battery cell body reaches a certain current / voltage, the current sensitive coating begins to expand, the thickness is increased, and gas is absorbed, so that the thermal diffusion of the battery cell can be improved from the level of the battery cell material, the separation between the battery cells is realized under a large current, and the service life of the battery cell is prolonged. The high temperature of the defective battery cell is prevented from being transferred to the adjacent battery cell, and the thermal diffusion reaction is inhibited at the initial stage.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a composite battery cell, a secondary battery and an electrical device. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] In recent years, as the application scope of secondary batteries becomes wider and wider, secondary batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. With the development of secondary battery technology, people have also put forward higher requirements for its safety. For example, thermal runaway of battery packs caused by heat diffusion between battery cells eventually leads to safety problems.

[0004] In the related art, physical components are often used to prevent the high temperature and heat of the problematic battery cell from being transferred to the adjacent battery cells, which is an external hemostasis method. Therefore, how to improve the thermal diffusion of the battery cell from the battery cell material level is an urgent problem to be solved. Summary of the invention

[0005] The present application provides a composite battery cell, a secondary battery, and an electrical device to improve the thermal diffusion of the battery cell at the battery cell material level, and effectively prevent the high temperature and heat of the problematic battery cell from being transferred to adjacent battery cells.

[0006] In order to achieve the above object, the first aspect of the present application provides a composite battery cell, comprising:

[0007] Battery cell body; and

[0008] A current sensitive coating coated on the surface of the battery body adjacent to other battery cells, wherein the current sensitive coating comprises a current sensitive material

[0009] Therefore, in the present application, a current-sensitive coating containing a current-sensitive material is provided. When the battery cell body reaches a certain current / voltage, the current-sensitive coating begins to expand, increase in thickness, and absorb gas, thereby improving the thermal diffusion of the battery cell from the battery cell material level, achieving isolation between battery cells under large currents, preventing the high temperature and heat of the problem battery cell from being transferred to adjacent battery cells, and suppressing the thermal diffusion reaction in the initial stage.

[0010] In some embodiments, the piezoelectric strain coefficient of the current sensitive material is 100 pC / N-1000 pC / N;

[0011] Optionally, the piezoelectric strain coefficient of the current sensitive material is 400 pC / N-1000 pC / N.

[0012] In some embodiments, the relative molecular mass of the current sensitive material is 150-1000; optionally 150-500.

[0013] In some embodiments, the current sensitive material comprises an inorganic piezoelectric material;

[0014] Optionally, the current sensitive material includes one or more of barium titanate piezoelectric materials, lead zirconate titanate piezoelectric materials and lead magnesium niobate piezoelectric materials.

[0015] In some embodiments, the ratio of the thickness of the coating to the thickness of the battery cell body is 0.01-0.1, and can be optionally 0.05-0.08.

[0016] In some embodiments, the current sensitive coating further comprises a carrier, and the current sensitive material is dispersed in the carrier.

[0017] In some embodiments, the mass ratio of the current sensitive material to the carrier is (7-27):3.

[0018] In some embodiments, the carrier includes one or more of a silicone resin, an epoxy resin, and a PE resin.

[0019] In some embodiments, the surface of the battery cell body except where the tabs are located is coated with the current sensitive coating.

[0020] A second aspect of the present invention provides a secondary battery comprising the composite battery cell according to the first aspect of the present invention.

[0021] In some embodiments, the secondary battery includes one or more of a lithium ion battery, a lithium metal battery, a sodium ion battery, and a sodium metal battery.

[0022] In some embodiments, the secondary battery includes one or more of a solid-state battery and a liquid battery.

[0023] The third aspect of the present invention provides an electrical device, which includes one or more of the composite battery cell of the first aspect of the present invention and the secondary battery of the second aspect of the present invention.

[0024] The electric device of the present application includes the secondary battery provided by the present application, and thus has at least the same advantages as the secondary battery.

[0025] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to better describe and illustrate the embodiments or examples provided by the present application, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes of these applications currently understood. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0027] Figure 1 It is a schematic diagram of a battery cell according to an embodiment of the present application.

[0028] Figure 2 for Figure 1 An exploded view of a battery cell according to an embodiment of the present application is shown.

[0029] Figure 3 It is a schematic diagram of a battery module according to one embodiment of the present application.

[0030] Figure 4 A schematic diagram of a battery pack according to an embodiment of the present application.

[0031] Figure 5 for Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0032] Figure 6 FIG. 1 is a schematic diagram of an electrical device using a secondary battery according to an embodiment of the present application as a power source.

[0033] Description of reference numerals:

[0034] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 cover plate; 6 electrical device. DETAILED DESCRIPTION

[0035] Below, some embodiments of the battery cell, secondary battery and electrical device of the present application are described in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure 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.

[0036] "Scope" disclosed in the present application can be limited in the form of lower limit and upper limit, and a 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 a special range. The scope limited in this way can be including end values ​​or excluding end values, and any end value can be included or not included independently, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are also listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present 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 real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation for these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to listing the parameter as, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0037] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0038] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0039] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. The "implementation methods" mentioned herein have a similar understanding.

[0040] Those skilled in the art will appreciate that, in the methods of each embodiment or example, the order in which each step is written does not mean a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can 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 steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0041] In the present application, in the open technical features or technical solutions described by the words "contain", "include", "comprise", etc., unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2 and a3. Unless otherwise specified, it may also include other members or may not include additional members. It can be regarded as providing both the feature or solution of "A consists of a1, a2 and a3" and the feature or solution of "A not only includes a1, a2 and a3, but also includes other members". In the present application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0042] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "option" is independent.

[0043] Generally, the heat sources of the battery cell usually include the following aspects: 1. Heat from the surrounding external objects, such as heat radiation, heat convection, heat transfer, hybrid internal combustion engine, battery heater with heating function or heat generated by the combustion of combustible gas leaked from the battery cell, etc.; 2. Heat generated by the action of current, such as heat generated by high resistance in the circuit outside the battery cell; 3. Heat generated by short circuit, such as heat generated by external short circuit in the circuit outside the battery cell, heat generated by internal short circuit of the battery cell itself (for example, dendrites, particles in the manufacturing process, short circuit between current collectors, etc.); 4. Heat generated by electrochemical reaction; for example, heat generated under overcharge conditions or low voltage and high current charging; 5. Heat generated by simple chemical reaction, such as heat generated by the reaction of positive and negative electrode materials with oxygen, etc.; 6. Heat generated by other expansion, etc. When the battery cell temperature is higher than 200°C, the positive active material decomposes to produce oxygen; thereafter, if the heat increases sharply, the battery cell will enter a thermal runaway state (such as fire, explosion, etc.); more serious is the occurrence of local high temperature and battery pack heat spread.

[0044] In the related art, in order to prevent the heat generated by the problematic battery cell from spreading to the adjacent battery cells, physical components are usually used (for example, adding a heat insulation pad outside the battery cell), which is an external hemostasis method. How to improve the heat diffusion of the battery cell from the battery cell material level is an urgent problem to be solved.

[0045] In addition, although adding thermal insulation pads can prevent high temperature and heat from being transferred to adjacent battery cells, it significantly affects battery performance and energy density.

[0046] Based on the above problems, the present application applies a current-sensitive coating containing current-sensitive materials to at least the surface of the battery cell adjacent to other battery cells. When the battery cell reaches a certain current / voltage, the current-sensitive coating begins to expand, the thickness increases, and the gas is absorbed, thereby improving the thermal diffusion of the battery cell from the battery cell material level and preventing the transfer of high temperature and heat between battery cells. And by adjusting the thickness of the current-sensitive coating, the effect of the coating on the battery cell performance and energy density can be controlled.

[0047] A first aspect of the present application provides a composite battery cell, comprising a battery cell body and a current-sensitive coating coated on a surface of the battery cell body adjacent to other battery cells, wherein the current-sensitive coating contains a current-sensitive material.

[0048] It should be noted that the current sensitive material refers to a material that expands in volume when a certain current or voltage is applied. The current sensitive coating refers to a material that contains the current sensitive material and expands in volume when a certain current or voltage is applied.

[0049] The "surface adjacent to other battery cells" mentioned above refers to the surface of the battery cell body that can transfer high temperature and heat to the adjacent battery cells. The "other battery cells" mentioned above can be battery cell bodies without current sensitive coatings, or composite battery cells coated with current sensitive coatings.

[0050] It can be understood that in the present application, a current-sensitive coating containing a current-sensitive material is provided. When the battery cell body reaches a certain current / voltage, the current-sensitive coating begins to expand, increase in thickness, and absorb gas, thereby improving the thermal diffusion of the battery cell from the battery cell material level, achieving isolation between battery cells under large currents, preventing the high temperature and heat of the problem battery cell from being transferred to adjacent battery cells, and suppressing the thermal diffusion reaction in the initial stage.

[0051] By setting a current-sensitive coating, the cascade reaction of thermal runaway of the battery pack can be avoided, and the fire or explosion of the battery pack can be suppressed. In addition, the current-sensitive coating has the advantages of high chemical stability, non-corrosiveness, low cost and good processing performance.

[0052] In some embodiments, the piezoelectric strain coefficient of the current sensitive material is 100pC / N-1000pC / N; for example, it can be but not limited to 100pC / N, 150pC / N, 200pC / N, 250pC / N, 300pC / N, 350pC / N, 400pC / N, 450pC / N, 500pC / N, 550pC / N, 600pC / N, 650pC / N, 700pC / N, 750pC / N, 800pC / N, 850pC / N, 900pC / N, 950pC / N, 1000pC / N or a range between any two of the above values. When the piezoelectric strain coefficient of the current sensitive material is within the above range, it can effectively expand and isolate high temperature and high heat transfer.

[0053] In some optional embodiments, the piezoelectric strain coefficient of the current sensitive material is 400 pC / N-1000 pC / N.

[0054] It should be noted that the piezoelectric strain coefficient refers to the ratio of the strain of the current sensitive material in a plane perpendicular to the direction of the electric field to the electric field intensity when an electric field is applied in the direction.

[0055] As an example, the piezoelectric strain coefficient of the current sensitive material mentioned above can be measured by the force-charge method, specifically: when the pressure applied to the sample changes suddenly, the charge generated on the sample will change, and the charge Q is measured by an impact galvanometer, then the piezoelectric strain coefficient d33 = Q / F, F is the applied pressure.

[0056] In some embodiments, the relative molecular mass of the current sensitive material is 150-1000; for example, it can be but not limited to 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000 or a range between any two of the above values. When the relative molecular mass of the current sensitive material is within the above range, it can effectively expand and isolate high temperature and high heat transfer, while having little effect on the weight increase of the battery.

[0057] In some optional embodiments, the relative molecular mass of the current sensitive material is 150-500.

[0058] In some embodiments, the current sensitive material includes an inorganic piezoelectric material.

[0059] In some optional embodiments, the current sensitive material includes one or more of a barium titanate-based piezoelectric material, a lead zirconate titanate-based piezoelectric material, and a lead magnesium niobate-based piezoelectric material.

[0060] It should be noted that there is an "inverse piezoelectric effect" in piezoelectric materials, that is, the electric field can cause the piezoelectric material to deform. Due to the piezoelectric effect, when voltage is applied, the piezoelectric material will stretch and expand in the direction of the voltage, and the polarization field strength will weaken. The inverse piezoelectric effect is partly an intrinsic effect formed by the piezoelectric displacement of ions in the material lattice, and partly an extrinsic effect based on the reversible ferroelectric redirection of the material unit cell. The extrinsic effect increases with the increase of the driving field strength. Within a certain range, there is a linear relationship between the elastic deformation of the piezoelectric material and the electric field or electric flux density. Therefore, the elastic deformation of the piezoelectric material can be controlled by applying a certain current or voltage to the piezoelectric material.

[0061] As a possible implementation, the ratio of the thickness of the current-sensitive coating to the thickness of the battery body is 0.01-0.1; for example, it can be but not limited to 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 or a range between any two of the above values. When the ratio of the thickness of the current-sensitive coating to the thickness of the battery body is within the above range, a good high-temperature and high-heat isolation effect can be achieved without significantly occupying the internal space of the battery; at the same time, since the current-sensitive coating does not significantly occupy the internal space of the battery, the impact on the performance and energy density of the battery cell is small. Optionally, the ratio of the thickness of the current-sensitive coating to the thickness of the battery body is 0.05-0.08.

[0062] Depending on the thickness of the battery cell body, the thickness of the current sensitive coating can be 0.3mm-2mm, 0.5mm-1mm, 0.3mm-0.5mm or 1mm-1.5mm, etc., without specific limitation.

[0063] It should be noted that, in practical applications, the thickness of the current sensitive coating can be appropriately adjusted according to the thickness of the battery body.

[0064] As an example, the thickness of the current sensitive coating and the ratio of the thickness of the current sensitive coating to the thickness of the battery cell body mentioned above can be measured using a leading packaging machine.

[0065] In some embodiments, the current sensitive coating further comprises a carrier, and the current sensitive material is dispersed in the carrier. By coating the current sensitive material and the carrier together on the surface of the battery body, the current sensitive material can be evenly dispersed on the surface of the battery body, thereby improving the blocking effect against high temperature and heat.

[0066] As a possible implementation, the mass ratio of the current sensitive material to the carrier in the current sensitive coating is (7-27):3; for example, it may be, but is not limited to, 7:3, 8:3, 7:3, 9:3, 10:3, 11:3, 12:3, 13:3, 14:3, 15:3, 16:3, 17:3, 18:3, 19:3, 20:3, 21:3, 22:3, 23:3, 24:3, 25:3, 26:3, 27:3 or a range between any two of the above ratios. When the mass ratio of the current sensitive material to the carrier is within the above range, it can effectively expand and isolate high temperature and high heat transfer, and the current sensitive material has a better adhesion effect on the battery surface.

[0068] In some embodiments, the carrier includes one or more of a silicone resin, an epoxy resin, and a PE resin.

[0069] In some optional embodiments, the surface of the battery cell body except where the tabs are located is coated with a current-sensitive coating, which can improve the barrier effect against high temperature and heat.

[0070] The second aspect of the present application provides a secondary battery, comprising the composite battery cell of the first aspect. The secondary battery comprising the composite battery cell of the present application can effectively prevent the transmission of high temperature and high heat, thereby improving safety.

[0071] In some embodiments, the secondary battery includes one or more of a lithium ion battery, a lithium metal battery, a sodium ion battery, and a sodium metal battery.

[0072] In some embodiments, the secondary battery includes one or more of a solid-state battery and a liquid battery.

[0073] In addition, the secondary battery and the electric device of the present application will be described below with reference to the drawings as appropriate.

[0074] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0075] Positive electrode

[0076] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material.

[0077] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0078] In some of the embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0079] In some optional embodiments, the positive electrode active material includes lithium nickel cobalt manganese oxide, wherein the chemical formula of the lithium nickel cobalt manganese oxide is Li x (Ni a Co b Mn c ) 1-d M d O2-yA y ; Wherein, 0.2≤x≤1.2, a≥0.6, b≤0.12, c≥0.08. Using high nickel material as positive electrode active material is beneficial to improving the energy density of secondary batteries.

[0080] In some optional embodiments, the positive electrode active material includes lithium manganese iron phosphate material Li a Mn1-yB y P1 z O4-D n (a is 0-1.1) and / or Lia A x Mn1-yB y P1 z O4-D n (where a+x is 0-1.1).

[0081] It should be noted that the above definition of x includes the molar content of Li under different charge and discharge states of the battery (usually the battery voltage is between 2-5V).

[0082] It is understandable that the battery will be accompanied by lithium (Li) deintercalation and consumption during the charging and discharging process, and the content of Li in the positive electrode plate is different when the battery is discharged to different states. In the list of positive electrode materials in this application, unless otherwise specified, the content of Li is the initial state of the material. The positive electrode material is applied to the positive electrode plate in the battery system, and after the charge and discharge cycle, the content of Li in the positive electrode material contained in the plate usually changes. Among them, the content of Li can be measured by molar content, but is not limited to this. Regarding "the content of Li is the initial state of the material", the initial state of the material refers to the state before the material is added to the positive electrode slurry. It is understandable that the new material obtained by appropriate modification on the basis of the listed positive electrode materials is also within the scope of the positive electrode material. The aforementioned appropriate modification refers to the acceptable modification method for the positive electrode material, and non-limiting examples include coating modification.

[0083] In the list of positive electrode materials in this application, the content of oxygen (O) is only a theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will fluctuate. Among them, the content of O can be measured by molar content, but is not limited to this.

[0084] In some of the embodiments, the positive electrode active material may be a positive electrode active material for a battery known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), 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 their modified compounds. Non-limiting examples of lithium-containing phosphates with 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 iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.85 Co 0.15 Al 0.05 O2.

[0085] In some embodiments, the positive electrode active material includes a sodium ion active material.

[0086] As an example, the sodium ion active material may include one or more of the following materials: one or more of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium ion batteries may also be used.

[0087] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Non-limiting examples of sodium transition metal oxides may include Na x MO2, wherein M may include one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0<x≤1.

[0088] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. Transition metals may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y may be one or more of P, S and Si; n represents (YO4) n- valence state.

[0089] Polyanionic compounds can also be those with sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. Transition metals may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y may be one or more of P, S and Si, and n represents (YO4) n- valence state; the halogen can be one or more of F, Cl and Br.

[0090] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedral unit (ZO y ) m+ and an optional halogen anion. Y can be one or more of P, S and Si, and n represents (YO4) n- valence state; Z represents a transition metal, which may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; m represents (ZO y ) m+ valence state; the halogen can be one or more of F, Cl and Br.

[0091] Polyanionic compounds may include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, referred to as NVP), Na4Fe3(PO4)2 (P2O7), NaM'PO4F and Na3(VO y )2(PO4)2F 3-2y (0≤y≤1) or more. Wherein, M' in NaM'PO4F may include one or more of V, Fe, Mn and Ni.

[0092] Prussian blue compounds can be sodium ions, transition metal ions and cyanide ions (CN - ). The transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Non-limiting examples of Prussian blue compounds may include Na a Me b Me' c (CN)6, wherein Me and Me' can be independently one or more of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0093] In some of these embodiments, the positive electrode active material layer may also optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0094] In some embodiments, the positive electrode active material layer may further include a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0095] In some of the embodiments, the positive electrode sheet can be prepared in the following manner: 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 to form a positive electrode slurry; the positive electrode slurry is coated on at least one side of the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained. The type of solvent can be selected from but not limited to any one of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector. The solid content of the positive electrode slurry can be 40wt% to 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000-25000mPa·s. When applying the positive electrode slurry, the coating unit area density based on dry weight (excluding solvent) can be 15-35 mg / cm 2 The compaction density of the positive electrode sheet can be 3.0 to 3.6 g / cm 3 , can be selected as 3.3~3.5g / cm 3 .

[0096] Negative electrode

[0097] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0098] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0099] In some of the embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0100] In some of the embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include one or more of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0101] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0102] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0103] In some of the embodiments, the negative electrode active material layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0104] In some of the embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the surface of the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode collector coated with the negative electrode slurry can be on a single surface of the negative electrode collector or on both surfaces of the negative electrode collector. The solid content of the negative electrode slurry can be 40wt% to 60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000-10000mPa·s. When coating the negative electrode slurry, the coating unit surface density on a dry weight basis (excluding the solvent) can be 75-220g / m 2 The compaction density of the negative electrode sheet can be 1.0g / cm 3 ~1.8g / cm 3 .

[0105] Electrolytes

[0106] The electrolyte has the function of conducting ions between the positive electrode and the negative electrode. The present application has no particular restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0107] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0108] In some of the embodiments, the electrolyte salt may include one or more of 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 difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0109] In some embodiments, the solvent may include 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 One or more of fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0110] In some embodiments, the electrolyte may further include additives, such as 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, additives that improve battery high or low temperature performance, etc.

[0111] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0112] Isolation film

[0113] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0114] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0115] In some embodiments, the isolation film has a thickness of 6-40 μm, and optionally 12-20 μm.

[0116] In some of the embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly by a winding process or a lamination process.

[0117] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0118] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and further, non-limiting examples of plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0119] The secondary battery includes at least one battery cell. The secondary battery may include one or more battery cells.

[0120] In this application, unless otherwise specified, "battery cell" refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy, and further, generally speaking, at least includes a positive electrode sheet, a negative electrode sheet and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet.

[0121] The present application has no particular restrictions on the shape of the battery cell, which can be cylindrical, square or any other shape. For example, Figure 1 The battery cell 5 is a square structure as an example.

[0122] In some of these embodiments, reference Figure 2, the outer packaging may include a shell 51 and a cover plate 53. Among them, 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 form 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 battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.

[0123] The secondary battery may be a battery module 4 or a battery pack 1 .

[0124] The battery module includes at least one battery cell. The number of battery cells contained in the battery module can be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery module.

[0125] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0126] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0127] In some of the embodiments, the battery modules may be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select a suitable number according to the application and capacity of the battery pack.

[0128] Figure 4 and Figure 5 1 is a battery pack 1 as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0129] In addition, the present application also provides an electrical device, which includes a secondary battery provided by the present application. The secondary battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto. Among them, the mobile device may be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but are not limited thereto.

[0130] As an electrical device, a secondary battery can be selected according to its usage requirements.

[0131] Figure 6 The power consumption device 6 is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of secondary batteries, a battery pack or a battery module can be used.

[0132] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0133] Example

[0134] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If the 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. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0135] 1. Preparation of composite battery cells

[0136] Example 1

[0137] Barium titanate (as current sensitive material) and N-methylpyrrolidone (NMP) were mixed evenly at a weight ratio of 30:1, and silicone resin (CAS67763-03-5) (as carrier) was added and stirred to form a slurry. The slurry was coated on the large surfaces of both sides of the battery body (such as Figure 2 The film was pressed into a film by NI-Y1 machine with a pressure of 7000±300kgF and a time of 70s to form a current sensitive coating with a thickness of 1mm.

[0138] Among them, the mass ratio of the current sensitive material to the carrier is 8:2; the silicone resin is purchased from Hubei Fangde New Materials Co., Ltd., model CAS67763-03-5; the thickness of the battery cell body is 50 mm.

[0139] Example 2-15

[0140] The preparation method of the composite battery cell in Examples 2-15 is basically similar to the preparation method of the composite battery cell in Example 1, and the main difference lies in: at least one of the type of current sensitive material, the mass ratio of the current sensitive material to the carrier, the type of carrier, and the thickness of the current sensitive coating is different, as shown in Table 1.

[0141] Comparative Example 1

[0142] The difference between Comparative Example 1 and Example 1 is that no current sensitive coating is applied, and the other aspects are the same.

[0143] The parameter settings of the above embodiments and comparative examples are shown in Table 1.

[0144] Table 1

[0145]

[0146] In Table 1, N1 represents the mass ratio of the current sensitive material to the carrier; d represents the thickness of the current sensitive coating; N2 represents the ratio of the thickness of the current sensitive coating to the thickness of the battery cell; the epoxy resin was purchased from Merck Reagent Co., Ltd., model 1675-54-3; the PE resin was purchased from ExxonMobil Chemical, model Exceed TM S

[0147] 2. Performance Test

[0148] On the large surface of the battery cell (such as Figure 2 The following thermal abuse test was carried out: the temperature was raised to 250°C at a rate of 3°C / min in a HE-REJ-72 constant temperature furnace and the temperature was maintained at the set temperature for 2 hours. The changes in the battery cells were monitored. The results are shown in Table 2.

[0149] The performance test results of the above embodiments and comparative examples are shown in Table 2.

[0150] Table 2

[0151]

[0152] From the comparison of the results of Examples 1-15 and the comparative example in Table 2, it can be seen that by coating the current sensitive coating on the surface of the battery cell body, the high temperature heat insulation of the problematic battery cell can be effectively blocked from being transferred to the adjacent battery cells.

[0153] The above description of various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced to each other, and for the sake of brevity, they will not be repeated herein.

[0154] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A composite battery cell, characterized in that: include: Battery cell body; and A current sensitive coating is coated on the surface of the battery cell body adjacent to other battery cells, wherein the current sensitive coating contains a current sensitive material.

2. The composite battery cell according to claim 1, characterized in that: The piezoelectric strain coefficient of the current sensitive material is 100pC / N-1000pC / N; Optionally, the piezoelectric strain coefficient of the current sensitive material is 400 pC / N-1000 pC / N.

3. The composite battery cell according to any one of claims 1 to 2, characterized in that: The relative molecular mass of the current sensitive material is 150-1000; optionally 150-500.

4. The composite battery cell according to any one of claims 1 to 3, characterized in that: The current sensitive material includes an inorganic piezoelectric material; Optionally, the current sensitive material includes one or more of barium titanate piezoelectric materials, lead zirconate titanate piezoelectric materials and lead magnesium niobate piezoelectric materials.

5. The composite battery cell according to any one of claims 1 to 4, characterized in that: The ratio of the thickness of the current sensitive coating to the thickness of the battery body is 0.01-0.1, and can be optionally 0.05-0.

08.

6. The composite battery cell according to any one of claims 1 to 5, characterized in that: The current sensitive coating further comprises a carrier, and the current sensitive material is dispersed in the carrier.

7. The composite battery cell according to claim 6, characterized in that: The mass ratio of the current sensitive material to the carrier is (7-27):

3.

8. The composite battery cell according to any one of claims 6 to 7, characterized in that: The carrier includes one or more of silicone resin, epoxy resin and PE resin.

9. The composite battery cell according to any one of claims 1 to 8, characterized in that: The surface of the battery body except the tabs is coated with the current sensitive coating.

10. A secondary battery, characterized in that: Comprising the composite battery cell as claimed in any one of claims 1 to 9.

11. The secondary battery according to claim 10, characterized in that: The secondary battery includes one or more of a lithium ion battery, a lithium metal battery, a sodium ion battery, and a sodium metal battery.

12. The secondary battery according to claim 10, characterized in that The secondary battery includes one or more of a solid-state battery and a liquid battery.

13. An electrical device, characterized in that: The invention comprises one or more of the composite battery cell according to any one of claims 1 to 9 and the secondary battery according to any one of claims 10 to 12.

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