Battery and electric device
By filling gas in the confined space of the battery to pressurize the solid-state battery cell, the problems of degradation in performance and internal short circuit during use are solved, and the reliability and service life of the battery are significantly improved.
Patent Information
- Application Number
- CN202421740629.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-22
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-07-22
AI Technical Summary
Existing solid-state batteries are prone to performance degradation or failure during use, and may even have risks such as internal short circuits, resulting in low reliability of the battery and short service life.
By filling the air in the enclosed space of the box, the air pressure in the enclosed space is greater than the air pressure outside the box, the solid battery cell is pressurized, thereby enhancing the contact area and contact effect between the first electrode sheet and the solid electrolyte layer and between the second electrode sheet and the solid electrolyte layer.
This design can effectively reduce the conductivity and fluctuations of the solid-state battery cells at different locations, reduce the risk of internal short circuits, and improve the reliability and service life of the battery.
Smart Images
Figure CN222995455U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of batteries, and more particularly, to a battery and an electrical device using the same. Background Art
[0002] In recent years, new energy vehicles have witnessed a leapfrog development. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. With the strong promotion of new energy vehicles, the demand for power battery products is also increasing day by day. Among them, as the core component of new energy vehicles, the battery has high requirements in terms of use reliability and service life.
[0003] In battery technology, in order to improve the energy density and charging speed of the battery, the battery is usually set as a solid-state battery, that is, the solid-state battery includes a box body and a solid-state battery cell accommodated in the box body. However, the existing solid-state battery cells are prone to performance degradation or failure during use, and even risks such as internal short circuits may occur, resulting in low use reliability and short service life of the battery. Summary of the Utility Model
[0004] The embodiments of the present application provide a battery and an electrical device using the same, which can effectively improve the use reliability and service life of the battery.
[0005] In a first aspect, the embodiments of the present application provide a battery, including a box body and a solid-state battery cell; a sealed space is formed inside the box body; the solid-state battery cell is disposed in the sealed space, and the solid-state battery cell includes a first electrode plate, a solid electrolyte layer, and a second electrode plate, the polarities of the first electrode plate and the second electrode plate are opposite, and the solid electrolyte layer is disposed between the first electrode plate and the second electrode plate to separate the first electrode plate and the second electrode plate; wherein, a gas is filled in the sealed space, and the air pressure in the sealed space is greater than the air pressure outside the box body.
[0006] In the above technical solution, by filling gas in the sealed space of the box body, the air pressure in the sealed space of the box body is made greater than the air pressure outside the box body, so that the gas in the sealed space of the box body can pressurize the solid-state battery cell, so as to increase the contact area and contact effect between the first electrode sheet and the solid electrolyte layer of the solid-state battery cell and between the second electrode sheet and the solid electrolyte layer. On the one hand, the battery with this structure can pressurize the solid-state battery cell from multiple directions, which is beneficial to increasing the contact area and contact effect at any position between the first electrode sheet and the solid electrolyte layer and between the second electrode sheet and the solid electrolyte layer. On the other hand, it can ensure that the external pressure on the solid-state battery cell is not affected by the shrinkage and expansion of the solid-state battery cell, so that the external pressure on the solid-state battery cell can remain constant. Therefore, during use, the phenomenon of reduced contact area or poor contact effect between the first electrode sheet and the solid electrolyte layer of the solid-state battery cell and between the second electrode sheet and the solid electrolyte layer can be alleviated, so as to reduce the phenomenon of different conductivity and fluctuations at different positions of the solid-state battery cell. Moreover, it can also alleviate the pollution phenomenon caused by the filler to the solid-state battery cell, and further effectively reduce the internal short-circuit risk brought by the ion metal deposition in the solid-state battery cell and the breakdown of the solid electrolyte layer. And it can effectively reduce the risk of performance degradation or even failure of the battery during use, which is beneficial to improving the use reliability and service life of the battery.
[0007] In some embodiments, the battery includes a plurality of the solid-state battery cells, and the plurality of solid-state battery cells are arranged at intervals in the sealed space, and a gap for accommodating the gas is formed between two adjacent solid-state battery cells.
[0008] In the above technical solution, by arranging a plurality of solid-state battery cells in the sealed space of the box body and arranging the plurality of solid-state battery cells at intervals, a gap for accommodating gas can be formed between two adjacent solid-state battery cells, so that while increasing the capacitance of the battery, the gas in the sealed space can pressurize the plurality of solid-state battery cells, and the phenomenon of poor pressurization effect of the solid-state battery cells caused by the mutual contact of the plurality of solid-state battery cells can be alleviated, which is beneficial to improving the pressurization effect on the plurality of solid-state battery cells.
[0009] In some embodiments, along a first direction, the solid-state battery cell has two opposite first surfaces, and the first surface is the surface with the largest area among the outer surfaces of the solid-state battery cell; wherein, the plurality of solid-state battery cells are arranged at intervals along the first direction.
[0010] In the above technical solution, the solid-state battery cell has two opposite first surfaces in the first direction, and the first surface is the surface with the largest area among the outer surfaces of the solid-state battery cell, so that the expansion and contraction amplitude of the solid-state battery cell in the first direction is the largest during use. Therefore, by arranging multiple solid-state battery cells at intervals in the first direction, the first surfaces of two adjacent solid-state battery cells can be made not to contact each other, so that the gas in the closed space can pressurize the first surface of the solid-state battery cell in the first direction, which is beneficial to improving the pressurization effect on the solid-state battery cell.
[0011] In some embodiments, the battery further includes a mounting rack; the mounting rack is arranged in the closed space, and multiple solid-state battery cells are mounted on the mounting rack at intervals.
[0012] In the above technical solution, by arranging a mounting rack in the box body of the battery and having a structure in which multiple solid-state battery cells are mounted on the mounting rack at intervals, on the one hand, a battery with this structure can reduce the difficulty of arranging multiple solid-state battery cells at intervals in the closed space. Multiple solid-state battery cells can be assembled on the mounting rack at intervals first and then assembled into the closed space of the box body, which is beneficial to reducing the assembly difficulty of the battery and optimizing the production process of the battery. On the other hand, it can make multiple solid-state battery cells form an integral structure through the mounting rack, which is beneficial to improving the stability and reliability of the assembly of multiple solid-state battery cells in the closed space.
[0013] In some embodiments, the mounting rack is connected to the box body.
[0014] In the above technical solution, by connecting the mounting rack and the box body to each other, it is beneficial to improve the stability of the mounting rack assembled in the closed space, so as to further improve the stability and reliability of the assembly of multiple solid-state battery cells in the closed space, and is beneficial to reducing the phenomenon of shaking or displacement of the solid-state battery cells in the closed space.
[0015] In some embodiments, the mounting rack is made of an insulating material.
[0016] In the above technical solution, by setting the mounting rack as an insulating material, it is beneficial to alleviate the short-circuit risk between the mounting rack and the solid-state battery cell, and can reduce the short-circuit risk between multiple solid-state battery cells.
[0017] In some embodiments, the solid-state battery cell is bonded to the mounting rack.
[0018] In the above technical solution, by using a bonded connection structure to assemble the solid-state battery cell on the mounting rack, on the one hand, it is convenient for the assembly between the solid-state battery cell and the mounting rack, which is beneficial to reducing the connection difficulty between the solid-state battery cell and the mounting rack. On the other hand, it can realize that the connection and assembly between the solid-state battery cell and the mounting rack do not affect the solid-state battery cell, which is beneficial to alleviating the phenomenon that the mounting rack damages the solid-state battery cell.
[0019] In some embodiments, the air pressure in the enclosed space is P, satisfying 0.2 MPa ≤ P ≤ 5 MPa.
[0020] In the above technical solution, by setting the air pressure in the enclosed space to be between 0.2 MPa and 5 MPa, on the one hand, setting the air pressure in the enclosed space to be greater than or equal to 0.2 MPa can improve the pressurizing effect on the solid-state battery cell, which is beneficial to further improving the contact area and contact effect at any position between the first electrode and the solid electrolyte layer and between the second electrode and the solid electrolyte layer. On the other hand, setting the air pressure in the enclosed space to be less than or equal to 5 MPa can reduce the manufacturing difficulty of the battery, and can reduce the requirements for the structural strength and materials of the box body, thereby reducing the manufacturing cost of the battery.
[0021] In some embodiments, a one-way inflation valve is provided on the box body, and the one-way inflation valve is configured to allow gas to enter the enclosed space and prevent gas from escaping from the box body.
[0022] In the above technical solution, by providing a one-way inflation valve on the box body, the one-way inflation valve can be used to inflate the enclosed space of the box body and prevent gas from escaping from the enclosed space, thereby facilitating the inflation and pressurization of the enclosed space of the box body and being beneficial to reducing the manufacturing difficulty of the battery.
[0023] In some embodiments, the box body includes a first box body and a second box body; an assembly cavity with an opening is formed inside the first box body; the second box body covers the opening, and the second box body and the first box body jointly define the enclosed space.
[0024] In the above technical solution, by setting the box body to include a structure of a first box body and a second box body, and the first box body and the second box body jointly form an enclosed space for accommodating the solid-state battery cell after being covered with each other. For a battery with such a structure, on the one hand, the forming difficulty of the enclosed space can be reduced, which is beneficial to reducing the manufacturing difficulty of the battery. On the other hand, the difficulty of assembling the solid-state battery cell into the enclosed space can be reduced, which is beneficial to reducing the assembly difficulty of the battery.
[0025] In some embodiments, the gas filled in the enclosed space is an inert gas.
[0026] In the above technical solution, by setting the gas filled in the enclosed space to be an inert gas, the phenomenon of the gas in the enclosed space reacting with the solid-state battery cell can be alleviated, and the phenomenon of the gas in the enclosed space polluting the solid-state battery cell can be reduced, thereby improving the use stability and service life of the battery.
[0027] In a second aspect, an embodiment of the present application further provides an electrical device, including the above-mentioned battery, and the battery is used to provide electrical energy. Description of the Drawings
[0028] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0029] Figure 1 Structural schematic diagram of a vehicle provided by some embodiments of the present application;
[0030] Figure 2 Structural schematic diagram of a battery provided by some embodiments of the present application;
[0031] Figure 3 Exploded view of the structure of a battery provided by some embodiments of the present application;
[0032] Figure 4 Cross-sectional view of a battery provided by some embodiments of the present application;
[0033] Figure 5 Front view of the battery (removing the second box body) in the second direction provided by some embodiments of the present application.
[0034] Reference numerals: 1000 - vehicle; 100 - battery; 10 - box body; 11 - enclosed space; 12 - first box body; 13 - second box body; 20 - solid-state battery cell; 21 - first surface; 30 - gap; 40 - mounting bracket; 200 - controller; 300 - motor; X - first direction; Y - second direction. Detailed Embodiments
[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.
[0036] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used in the description of this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above-mentioned drawings are used to distinguish different objects and not to describe a specific order or primary-secondary relationship.
[0037] Reference to "embodiment" in this application means that a specific feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.
[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "joined", and "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0039] The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.
[0040] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, etc. of various components in the embodiments of this application shown in the drawings, as well as the overall thickness, length, width, etc. of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.
[0041] The term "plurality" as used in this application refers to two or more (including two).
[0042] In the embodiments of this application, the solid-state battery cell can be a secondary battery, and a secondary battery refers to a solid-state battery cell that can be activated by charging after discharging so as to continue to be used.
[0043] The solid-state battery cell can be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, etc., and the embodiments of the present application are not limited thereto.
[0044] The solid-state battery cell generally includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the solid-state battery cell, active ions (such as lithium ions) are inserted and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can prevent the short circuit between the positive and negative electrodes and allow the active ions to pass through.
[0045] In some embodiments, the positive electrode can be a positive electrode sheet, and the positive electrode sheet can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.
[0046] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
[0047] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum with silver plating on the surface, stainless steel with silver plating on the surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).
[0048] As an example, the positive electrode active material can include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphate can include but are not limited to lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, etc. Examples of lithium transition metal oxides can include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM333 )), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 )), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 )), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 )), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 )), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.
[0049] In some embodiments, the positive electrode can employ a foam metal. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, etc. When the foam metal serves as the positive electrode, the positive electrode active material may not be provided on the surface of the foam metal, and of course, the positive electrode active material can also be provided. As an example, a lithium source material, potassium metal, or sodium metal can also be filled or / and deposited in the foam metal, and the lithium source material is lithium metal and / or lithium-rich material.
[0050] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative electrode current collector.
[0051] As an example, the negative electrode current collector can employ a metal foil, foam metal, or composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. can be used. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).
[0052] As an example, the negative electrode sheet can include a negative electrode current collector and a negative electrode active material provided on at least one surface of the negative electrode current collector.
[0053] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material is provided on any one or both of the two opposite surfaces of the negative electrode current collector.
[0054] As an example, the negative electrode active material can be a negative electrode active material for a solid-state battery cell known in the art. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.
[0055] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.
[0056] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive electrode and the negative electrode, and simultaneously functions to transport ions and isolate the positive and negative electrodes.
[0057] Among them, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.
[0058] As an example, the polymer solid electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, polyionic liquid-lithium salt, cellulose, etc.
[0059] As an example, the inorganic solid electrolyte can include oxide solid electrolytes (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), sulfide solid electrolytes (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and one or more of halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.
[0060] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to the polymer solid electrolyte.
[0061] In some embodiments, the solid-state battery cell is of a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.
[0062] In some embodiments, the solid-state battery cell is of a stacked structure.
[0063] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be respectively provided, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked.
[0064] As an example, multiple positive electrode sheets may be provided. The negative electrode sheet is folded to form multiple stacked folding segments, and a positive electrode sheet is clamped between adjacent folding segments.
[0065] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form multiple stacked folding segments.
[0066] As an example, multiple separators may be provided and are respectively disposed between any adjacent positive electrode sheets or negative electrode sheets.
[0067] As an example, the separators may be continuously provided and are disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.
[0068] In some embodiments, the shape of the solid-state battery cell may be cylindrical, flat, prismatic, or the like.
[0069] As an example, the solid-state battery cell may be a cylindrical solid-state battery cell, a prismatic solid-state battery cell, a soft-pack solid-state battery cell, or a solid-state battery cell of other shapes.
[0070] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more solid-state battery cells to provide higher voltage and capacity.
[0071] In some embodiments, the battery may be a battery module. When there are multiple solid-state battery cells, the multiple solid-state battery cells are arranged and fixed to form a battery module.
[0072] In some embodiments, the battery may be a battery pack. The battery pack includes a box body and solid-state battery cells, and the solid-state battery cells or the battery module are accommodated in the box body.
[0073] In some embodiments, the box body may be part of the chassis structure of a vehicle. For example, a part of the box body may become at least a part of the floor of the vehicle, or a part of the box body may become at least a part of the cross beam and longitudinal beam of the vehicle.
[0074] In some embodiments, the battery may be an energy storage device. The energy storage device includes an energy storage container, an energy storage electrical cabinet, etc.
[0075] The battery has outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide application range, and small self-discharge coefficient, and is an important part of the development of new energy today. The development of battery technology needs to consider various design factors at the same time, such as performance parameters such as energy density, cycle life, discharge capacity, charge and discharge rate, etc.
[0076] In battery technology, in the related art, in order to improve the energy density and charging speed of a battery, the battery is usually set as a solid-state battery, that is, the solid-state battery includes a box body and a solid-state battery cell accommodated in the box body. Among them, the solid-state battery cell includes a positive electrode sheet, a negative electrode sheet, and a solid electrolyte layer disposed between the positive electrode sheet and the negative electrode sheet. However, since the transfer of electrons and ions between the positive electrode sheet, the solid electrolyte layer, and the negative electrode sheet of the solid-state battery cell is carried out through the mutual contact of particles, external pressure needs to be applied to the solid-state battery cell to increase the contact area and contact effect between the positive and negative electrode sheets and the solid electrolyte layer. However, due to the volume shrinkage and expansion effect of the material itself during the charge and discharge process of the solid-state battery cell in the related art, a very large stress accumulation will occur inside the solid-state battery cell, so that the externally applied pressure cannot always remain constant. As a result, during the use of the solid-state battery cell, the contact area between the positive and negative electrode sheets and the solid electrolyte layer will decrease or the contact effect will be poor, resulting in different conductivities and fluctuations at different positions of the solid-state battery cell. On the one hand, it is very easy to cause the phenomenon of ionic metal deposition during the use of the solid-state battery cell. Even after excessive ionic metal deposition, it will cause the breakdown of the solid electrolyte layer, resulting in the risk of internal short circuit during the use of the solid-state battery cell. On the other hand, it is very easy to cause phenomena such as performance degradation or even failure of the battery, which is not conducive to improving the use reliability and service life of the battery.
[0077] Based on the above considerations, in order to solve the problems of low use reliability and short service life of the battery, the embodiment of the present application provides a battery, which includes a box body and a solid-state battery cell. A sealed space is formed inside the box body. The solid-state battery cell is disposed in the sealed space. The solid-state battery cell includes a first electrode sheet, a solid electrolyte layer, and a second electrode sheet. The polarities of the first electrode sheet and the second electrode sheet are opposite. The solid electrolyte layer is disposed between the first electrode sheet and the second electrode sheet to separate the first electrode sheet and the second electrode sheet. The sealed space is filled with gas, and the air pressure in the sealed space is greater than the air pressure outside the box body.
[0078] In the battery with such a structure, by filling gas in the sealed space of the box body, the air pressure in the sealed space of the box body is made greater than the air pressure outside the box body, so that the gas in the sealed space of the box body can pressurize the solid-state battery cell, so as to increase the contact area and contact effect between the first electrode and the solid electrolyte layer of the solid-state battery cell and between the second electrode and the solid electrolyte layer. On the one hand, using a battery with such a structure can pressurize the solid-state battery cell from multiple directions, which is beneficial to increasing the contact area and contact effect at any position between the first electrode and the solid electrolyte layer and between the second electrode and the solid electrolyte layer. On the other hand, it can ensure that the external pressure on the solid-state battery cell is not affected by the contraction and expansion of the solid-state battery cell, so that the external pressure on the solid-state battery cell can remain constant. Thus, during use, it can alleviate the phenomenon that the contact area between the first electrode and the solid electrolyte layer of the solid-state battery cell and between the second electrode and the solid electrolyte layer decreases or the contact effect is poor, so as to reduce the phenomenon of different conductivity and fluctuations at different positions of the solid-state battery cell. Moreover, it can also alleviate the pollution phenomenon caused by the filler to the solid-state battery cell, and further effectively reduce the risk of internal short circuit caused by the deposition of ionic metal on the solid-state battery cell and the breakdown of the solid electrolyte layer. And it can effectively reduce the risk of performance degradation or even failure of the battery during use, which is beneficial to improving the reliability and service life of the battery.
[0079] The battery disclosed in the embodiments of the present application can be but is not limited to being used in power-consuming devices such as vehicles, ships or aircraft. A power supply system of the power-consuming device can be composed of the battery disclosed in the present application. In this way, it is beneficial to alleviate the problems of internal short circuit or performance degradation of the battery during use, so as to improve the reliability and service life of the battery.
[0080] The embodiments of the present application provide a power-consuming device using a battery as a power source. The power-consuming device can be but is not limited to mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, ships, spacecrafts, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys and electric aircraft toys, etc. The spacecraft can include airplanes, rockets, space shuttles and spaceships, etc.
[0081] For the convenience of description, the following embodiments take a power-consuming device of an embodiment of the present application as a vehicle as an example for description.
[0082] Please refer to Figure 1 , Figure 1Schematic structural diagram of vehicle 1000 provided by some embodiments of the present application. Vehicle 1000 can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc. A battery 100 is disposed inside vehicle 1000. The battery 100 can be disposed at the bottom of vehicle 1000, or at the head of vehicle 1000, or at the tail of vehicle 1000. The battery 100 can be used to supply power to vehicle 1000. For example, the battery 100 can be used as the operating power source or the power source for use of vehicle 1000. Vehicle 1000 can further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300. For example, it is used for the working power requirements during the start, navigation, and driving of vehicle 1000.
[0083] In some embodiments of the present application, the battery 100 can not only be used as the operating power source or the power source for use of vehicle 1000, but also be used as the driving power source of vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for vehicle 1000.
[0084] According to some embodiments of the present application, referring to Figure 2 , Figure 3 and Figure 4 , Figure 2 Schematic structural diagram of battery 100 provided by some embodiments of the present application, Figure 3 Exploded view of the structure of battery 100 provided by some embodiments of the present application, Figure 4 Cross-sectional view of battery 100 provided by some embodiments of the present application. The present application provides a battery 100, which includes a box body 10 and a solid-state battery cell 20. A sealed space 11 is formed inside the box body 10. The solid-state battery cell 20 is disposed in the sealed space 11. The solid-state battery cell 20 includes a first electrode plate, a solid electrolyte layer, and a second electrode plate. The polarities of the first electrode plate and the second electrode plate are opposite. The solid electrolyte layer is disposed between the first electrode plate and the second electrode plate to separate the first electrode plate and the second electrode plate. The sealed space 11 is filled with gas, and the air pressure inside the sealed space 11 is greater than the air pressure outside the box body 10.
[0085] Among them, the box body 10 is used to provide an assembly space for the solid-state battery cell 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 may include a first box body 12 and a second box body 13. The first box body 12 and the second box body 13 cover each other, and the first box body 12 and the second box body 13 jointly define a sealed space 11 for accommodating the solid-state battery cell 20. The first box body 12 may be a hollow structure with an opening formed at one end, and the second box body 13 may be a plate-like structure. The second box body 13 covers the opening of the first box body 12 so that the first box body 12 and the second box body 13 jointly define the sealed space 11; the first box body 12 and the second box body 13 may also both be hollow structures with an opening formed at one side, and the opening of the first box body 12 covers the opening of the second box body 13.
[0086] Of course, the box body 10 formed by the first box body 12 and the second box body 13 can be of various shapes, such as, a cylinder, a cuboid or a cube, etc. Exemplarily, in Figure 2 it, the shape of the box body 10 is a cuboid.
[0087] In the battery 100, the solid-state battery cell 20 arranged in the box body 10 can be one or multiple. When there are multiple solid-state battery cells 20 arranged in the box body 10, the multiple solid-state battery cells 20 can be connected in series, in parallel or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple solid-state battery cells 20. The multiple solid-state battery cells 20 can be directly connected in series, in parallel or in a mixed connection together, and then the whole formed by the multiple solid-state battery cells 20 is accommodated in the box body 10; of course, the battery 100 can also be that multiple solid-state battery cells 20 are first connected in series, in parallel or in a mixed connection to form a battery module form, and then multiple battery modules are connected in series, in parallel or in a mixed connection to form a whole and are integrally accommodated in the box body 10.
[0088] In some embodiments, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, and the busbar component is used to connect the multiple solid-state battery cells 20 to achieve electrical connection among the multiple solid-state battery cells 20.
[0089] Optionally, the shape of the solid-state battery cell 20 can be various. For example, the solid-state battery cell 20 can be in the shape of a cuboid, a cylinder, a prism or other shapes, etc. Exemplarily, in Figure 3 it, the solid-state battery cell 20 is of a cuboid structure.
[0090] The solid-state battery cell 20 includes a first electrode, a solid electrolyte layer and a second electrode. The polarities of the first electrode and the second electrode are opposite, that is, the first electrode and the second electrode are respectively used to input or output the positive electrode and the negative electrode of the solid-state battery cell 20. It should be noted that the first electrode, the solid electrolyte layer and the second electrode can be a laminated structure formed by laminating each other, or a wound structure formed by winding each other.
[0091] The solid electrolyte layer is disposed between the first electrode and the second electrode to separate the first electrode and the second electrode. That is to say, the solid electrolyte layer is located between the first electrode and the second electrode, which can not only play the role of transporting ions and electrons, but also separate the first electrode and the second electrode to reduce the risk of short circuit between the first electrode and the second electrode.
[0092] Exemplarily, the solid electrolyte layer can be a polymer solid electrolyte layer, an inorganic solid electrolyte layer, a composite solid electrolyte layer, etc.
[0093] Wherein, the first electrode may include a first current collector and a first active material layer disposed on the surface of the first current collector facing the solid electrolyte layer. Correspondingly, the second electrode includes a second current collector and a second active material layer disposed on the surface of the second current collector facing the solid electrolyte layer, so that the solid electrolyte layer is located between the first active material layer of the first electrode and the second active material layer of the second electrode.
[0094] Exemplarily, if the first electrode is a negative electrode, then the second electrode is a positive electrode. Correspondingly, the first active material layer of the first electrode includes a negative active material, and the second active material layer of the second electrode includes a positive active material. Of course, in other embodiments, the first electrode can also be a positive electrode, and the second electrode is a negative electrode.
[0095] The closed space 11 is filled with gas, and the air pressure in the closed space 11 is greater than the air pressure outside the box body 10. That is to say, the gas filled in the closed space 11 covers the outside of the solid-state battery cell 20, so that the pressure of the gas in the closed space 11 can act on the outer surface of the solid-state battery cell 20 to pressurize the solid-state battery cell 20, thereby increasing the contact effect between the first electrode and the solid electrolyte layer and between the second electrode and the solid electrolyte layer.
[0096] Exemplarily, there can be various gases filled in the closed space 11, such as air, nitrogen, helium, neon, argon, krypton or xenon, etc.
[0097] In this embodiment, by filling a gas in the sealed space 11 of the box body 10, the air pressure in the sealed space 11 of the box body 10 is made greater than the air pressure outside the box body 10, so that the gas in the sealed space 11 of the box body 10 can pressurize the solid-state battery cell 20, in order to increase the contact area and contact effect between the first electrode sheet and the solid electrolyte layer of the solid-state battery cell 20 and between the second electrode sheet and the solid electrolyte layer. With this structure, on the one hand, the battery 100 can pressurize the solid-state battery cell 20 from multiple directions, which is beneficial to increasing the contact area and contact effect at any position between the first electrode sheet and the solid electrolyte layer and between the second electrode sheet and the solid electrolyte layer. On the other hand, it can be ensured that the external pressure received by the solid-state battery cell 20 is not affected by the shrinkage and expansion of the solid-state battery cell 20, so that the external pressure received by the solid-state battery cell 20 can remain constant. Therefore, during use, the phenomenon of reduction in the contact area or poor contact effect between the first electrode sheet and the solid electrolyte layer of the solid-state battery cell 20 and between the second electrode sheet and the solid electrolyte layer can be alleviated, so as to reduce the phenomena such as different conductivity and fluctuations at different positions of the solid-state battery cell 20. Moreover, it can also alleviate the pollution phenomenon caused by the filler to the solid-state battery cell 20, and further can effectively reduce the risk of internal short circuit caused by the deposition of ionic metal on the solid-state battery cell 20 and the breakdown of the solid electrolyte layer. And it can effectively reduce the risk of performance degradation or even failure of the battery 100 during use, which is beneficial to improving the reliability and service life of the battery 100.
[0098] According to some embodiments of the present application, referring to Figure 3 and Figure 4 , and further referring to Figure 5 , Figure 5 is a front view of the battery 100 (removing the second box body 13) provided by some embodiments of the present application in the second direction Y. The battery 100 includes a plurality of solid-state battery cells 20, and the plurality of solid-state battery cells 20 are arranged at intervals in the sealed space 11, and a gap 30 for accommodating gas is formed between two adjacent solid-state battery cells 20.
[0099] Wherein, a gap 30 for accommodating gas is formed between two adjacent solid-state battery cells 20, that is, the plurality of solid-state battery cells 20 are arranged at intervals, and a gap 30 is formed between every two adjacent solid-state battery cells 20. Correspondingly, the gap 30 can accommodate the gas filled in the sealed space 11.
[0100] Exemplarily, in Figure 4 , the plurality of solid-state battery cells 20 are arranged at intervals along the first direction X, and a gap 30 is formed between every two adjacent solid-state battery cells 20 in the first direction X.
[0101] In this embodiment, by arranging a plurality of solid-state battery cells 20 in the enclosed space 11 of the battery case 10, and arranging the plurality of solid-state battery cells 20 at intervals, a gap 30 for accommodating gas can be formed between two adjacent solid-state battery cells 20. Thus, while increasing the capacitance of the battery 100, the gas in the enclosed space 11 can pressurize the plurality of solid-state battery cells 20, and the phenomenon that the pressurizing effect of the solid-state battery cells 20 is poor due to the mutual contact of the plurality of solid-state battery cells 20 can be alleviated, which is beneficial to improving the pressurizing effect on the plurality of solid-state battery cells 20.
[0102] According to some embodiments of the present application, referring to Figure 4 and Figure 5 As shown, along the first direction X, the solid-state battery cell 20 has two opposite first surfaces 21. The first surface 21 is the surface with the largest area among the outer surfaces of the solid-state battery cell 20, and the plurality of solid-state battery cells 20 are arranged at intervals along the first direction X.
[0103] Among them, the solid-state battery cell 20 has a cuboid structure. The first surface 21 is the surface on one side of the solid-state battery cell 20 in the first direction X, and the first surface 21 is the surface with the largest area among the outer surfaces of the solid-state battery cell 20. That is, the first direction X is the thickness direction of the solid-state battery cell 20, and the first surface 21 is the surface on one side of the solid-state battery cell 20 in the thickness direction of the solid-state battery cell 20.
[0104] The plurality of solid-state battery cells 20 are arranged at intervals along the first direction X, that is, the plurality of solid-state battery cells 20 are arranged at intervals along the thickness direction of the solid-state battery cell 20.
[0105] In this embodiment, the solid-state battery cell 20 has two opposite first surfaces 21 in the first direction X, and the first surface 21 is the surface with the largest area among the outer surfaces of the solid-state battery cell 20, so that the expansion and contraction amplitude of the solid-state battery cell 20 in the first direction X is the largest during use. Thus, by arranging the plurality of solid-state battery cells 20 at intervals along the first direction X, the first surfaces 21 of two adjacent solid-state battery cells 20 can be prevented from contacting each other, so that the gas in the enclosed space 11 can pressurize the first surfaces 21 of the solid-state battery cells 20 in the first direction X, which is beneficial to improving the pressurizing effect on the solid-state battery cells 20.
[0106] According to some embodiments of the present application, referring to Figure 3 、 Figure 4 and Figure 5 As shown, the battery 100 may further include a mounting rack 40. The mounting rack 40 is arranged in the enclosed space 11, and the plurality of solid-state battery cells 20 are mounted on the mounting rack 40 at intervals.
[0107] Among them, the mounting rack 40 serves to assemble and fix multiple solid-state battery cells 20. The mounting rack 40 can be made of non-metallic materials. For example, the material of the mounting rack 40 can be ceramics, rubber, silica gel, carbon fiber, or plastic, etc. Of course, the mounting rack 40 can also be made of metallic materials. For example, the material of the mounting rack 40 can be copper, iron, aluminum, or aluminum alloy, etc.
[0108] Similarly, the structure of mounting the solid-state battery cells 20 on the mounting rack 40 can also be various. For example, the solid-state battery cells 20 can be mounted on the mounting rack 40 through structures such as bonding and clamping.
[0109] In this embodiment, by arranging the mounting rack 40 in the box body 10 of the battery 100, and the multiple solid-state battery cells 20 are arranged at intervals on the mounting rack 40. On the one hand, the battery 100 with this structure can reduce the difficulty of arranging the multiple solid-state battery cells 20 at intervals in the closed space 11. It is possible to first assemble the multiple solid-state battery cells 20 at intervals on the mounting rack 40 and then assemble them into the closed space 11 of the box body 10, which is beneficial to reducing the assembly difficulty of the battery 100 and optimizing the production process of the battery 100. On the other hand, it can make the multiple solid-state battery cells 20 form an integral structure through the mounting rack 40, which is beneficial to improving the stability and reliability of the multiple solid-state battery cells 20 assembled in the closed space 11.
[0110] In some embodiments, referring to Figure 4 and Figure 5 as shown, the mounting rack 40 is connected to the box body 10.
[0111] Exemplarily, the structure of connecting the mounting rack 40 to the box body 10 can be various. For example, bonding, clamping, or bolt screwing, etc.
[0112] In this embodiment, by connecting the mounting rack 40 and the box body 10 to each other, it is beneficial to improve the stability of the mounting rack 40 assembled in the closed space 11, so as to further improve the stability and reliability of the multiple solid-state battery cells 20 assembled in the closed space 11, and is beneficial to reducing the phenomenon of shaking or displacement of the solid-state battery cells 20 in the closed space 11.
[0113] In some embodiments, the mounting rack 40 is made of insulating material.
[0114] Exemplarily, the material of the mounting rack 40 can be rubber, silica gel, or plastic, etc.
[0115] In this embodiment, by setting the mounting rack 40 as an insulating material, it is beneficial to alleviate the short-circuit risk between the mounting rack 40 and the solid-state battery cells 20, and can reduce the short-circuit risk between the multiple solid-state battery cells 20.
[0116] In some embodiments, the solid-state battery cells 20 are bonded to the mounting rack 40.
[0117] Exemplarily, the solid-state battery cell 20 can be adhesively connected to the mounting bracket 40 through structures such as double-sided tape, glue, or hot melt adhesive.
[0118] In this embodiment, the solid-state battery cell 20 is assembled on the mounting bracket 40 by an adhesive connection structure. On the one hand, it facilitates the assembly between the solid-state battery cell 20 and the mounting bracket 40, which is beneficial to reducing the connection difficulty between the solid-state battery cell 20 and the mounting bracket 40. On the other hand, it can ensure that the connection and assembly between the solid-state battery cell 20 and the mounting bracket 40 do not affect the solid-state battery cell 20, which is beneficial to alleviating the phenomenon that the mounting bracket 40 damages the solid-state battery cell 20.
[0119] According to some embodiments of the present application, the air pressure in the closed space 11 is P, satisfying 0.2 MPa ≤ P ≤ 5 MPa. That is to say, the pressure of the gas filled in the closed space 11 is from 0.2 MPa to 5 MPa.
[0120] Exemplarily, the air pressure P in the closed space 11 can be 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.5 MPa, 2.8 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, or 5 MPa, etc.
[0121] In this embodiment, by setting the air pressure in the closed space 11 to be from 0.2 MPa to 5 MPa, on the one hand, setting the air pressure in the closed space 11 to be greater than or equal to 0.2 MPa can improve the pressurizing effect on the solid-state battery cell 20, which is beneficial to further improving the contact area and contact effect at any position between the first electrode and the solid electrolyte layer and between the second electrode and the solid electrolyte layer. On the other hand, setting the air pressure in the closed space 11 to be less than or equal to 5 MPa can reduce the manufacturing difficulty of the battery 100, and can reduce the requirements for the structural strength and materials of the box body 10, thereby reducing the manufacturing cost of the battery 100.
[0122] According to some embodiments of the present application, a one-way inflation valve (not shown in the figure) is provided on the box body 10, and the one-way inflation valve is configured to allow gas to enter the closed space 11 and prevent gas from discharging from the box body 10.
[0123] Among them, in the embodiment where the box body 10 includes a first box body 12 and a second box body 13, the one-way inflation valve can be provided on the first box body 12 or on the second box body 13. For the specific structure of the one-way inflation valve, reference can be made to the related art and will not be elaborated here.
[0124] In this embodiment, a one-way inflation valve is provided on the box body 10, so that the closed space 11 of the box body 10 can be inflated through the one-way inflation valve and the gas can be prevented from discharging from the closed space 11, thereby facilitating the inflation and pressurization of the closed space 11 of the box body 10 and being beneficial to reducing the manufacturing difficulty of the battery 100.
[0125] According to some embodiments of the present application, referring to Figure 2 , Figure 3 and Figure 4 as shown, the box body 10 may include a first box body 12 and a second box body 13. An assembly cavity with an opening is formed inside the first box body 12, and the second box body 13 covers the opening. The second box body 13 and the first box body 12 jointly define a closed space 11.
[0126] Exemplarily, in Figure 3 and Figure 4 , the first box body 12 and the second box body 13 are structures arranged along the second direction Y and covering each other. It should be noted that in the embodiment where the battery 100 includes a plurality of solid-state battery cells 20 and the plurality of solid-state battery cells 20 are arranged at intervals along the first direction X, the first box body 12 and the second box body 13 are structures covering each other along the second direction Y, and the second direction Y is perpendicular to the first direction X, so that the arrangement direction of the first box body 12 and the second box body 13 is perpendicular to the arrangement direction of the plurality of solid-state battery cells 20, thereby facilitating the assembly of the plurality of solid-state battery cells 20 into the box body 10 and being beneficial to reducing the assembly difficulty of the battery 100 to improve the production efficiency of the battery 100.
[0127] In this embodiment, by setting the box body to include the first box body 12 and the second box body 13, and the first box body 12 and the second box body 13 jointly form a closed space 11 for accommodating the solid-state battery cells 20 after covering each other. On the one hand, the battery 100 with this structure can reduce the forming difficulty of the closed space 11 and is beneficial to reducing the manufacturing difficulty of the battery 100. On the other hand, it can reduce the difficulty of assembling the solid-state battery cells 20 into the closed space 11 and is beneficial to reducing the assembly difficulty of the battery 100.
[0128] According to some embodiments of the present application, the gas filled in the closed space 11 is an inert gas.
[0129] Exemplarily, the gas filled in the closed space 11 may be helium, neon, argon, krypton or xenon, etc.
[0130] In this embodiment, by setting the gas filled in the sealed space 11 as an inert gas, the phenomenon that the gas in the sealed space 11 reacts with the solid-state battery cell 20 can be alleviated, and the phenomenon that the gas in the sealed space 11 contaminates the solid-state battery cell 20 can be reduced. Furthermore, the service stability and service life of the battery 100 can be improved.
[0131] According to some embodiments of the present application, the present application further provides an electrical device, which includes the battery 100 of any of the above solutions, and the battery 100 is used to provide electrical energy for the electrical device.
[0132] Among them, the electrical device may be any of the aforementioned devices or systems that apply the battery 100.
[0133] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.
[0134] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A battery, characterized in that: include: A box body, with a closed space formed inside; as well as A solid-state battery cell is arranged in the enclosed space, the solid-state battery cell comprises a first pole piece, a solid electrolyte layer and a second pole piece, the first pole piece and the second pole piece have opposite polarities, and the solid electrolyte layer is arranged between the first pole piece and the second pole piece to separate the first pole piece from the second pole piece; The enclosed space is filled with gas, and the air pressure in the enclosed space is greater than the air pressure outside the box.
2. The battery according to claim 1, characterized in that The battery comprises a plurality of the solid-state battery cells, which are arranged at intervals in the enclosed space, and a gap for accommodating the gas is formed between two adjacent solid-state battery cells.
3. The battery according to claim 2, characterized in that Along a first direction, the solid-state battery core has two opposite first surfaces, and the first surface is the surface with the largest area among the outer surfaces of the solid-state battery core; Wherein, a plurality of the solid-state battery cells are arranged at intervals along the first direction.
4. The battery according to claim 2, characterized in that The battery also includes: A mounting frame is arranged in the enclosed space, and a plurality of the solid-state battery cells are installed on the mounting frame at intervals.
5. The battery according to claim 4, characterized in that The mounting frame is connected to the box.
6. The battery according to claim 4, characterized in that The mounting frame is made of insulating material.
7. The battery according to claim 4, characterized in that The solid-state battery core is bonded to the mounting frame.
8. The battery according to any one of claims 1 to 7, characterized in that The air pressure in the enclosed space is P, which satisfies 0.2MPa≤P≤5MPa.
9. The battery according to any one of claims 1 to 7, characterized in that The box body is provided with a one-way inflation valve, and the one-way inflation valve is configured to allow gas to enter the enclosed space and prevent gas from being discharged from the box body.
10. The battery according to any one of claims 1 to 7, characterized in that The box body comprises: A first box body, an assembly cavity with an opening formed therein; The second box body covers the opening, and the second box body and the first box body together define the enclosed space.
11. The battery according to any one of claims 1 to 7, characterized in that The gas filled in the enclosed space is an inert gas.
12. An electrical device, characterized in that: The invention comprises a battery as claimed in any one of claims 1 to 11, wherein the battery is used to provide electrical energy.