Method for evaluating air stability of sulfide solid-state battery

Abstract

The application discloses a sulfide solid-state battery air stability evaluation method, comprising the following steps: providing a sulfide solid-state battery; disassembling the sulfide solid-state battery package to obtain an electrode assembly; placing the electrode assembly in a closed environment, and standing for a target time under a target humidity; and determining the hydrogen sulfide content in the closed environment statically. The sulfide solid-state battery air stability evaluation method provided by the application can be applied to the air stability detection of different types of sulfide solid-state batteries.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a method for evaluating the air stability of sulfide solid-state batteries. Background Technology

[0002] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0003] When solid-state batteries use sulfide electrolytes, the sulfides are prone to deliquescence in humid air, generating H2S, which leads to a decline in electronic and ionic conductivity. Different formulations of sulfide electrolytes exhibit vastly different conductivity properties, making it impossible to evaluate their air stability using conductivity alone. Therefore, providing a method to evaluate the air stability of various types of sulfide solid-state batteries is a pressing issue that needs to be addressed. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for evaluating the air stability of sulfide solid-state batteries, comprising the following steps:

[0005] Provides sulfide solid-state batteries;

[0006] The electrode assembly is obtained by removing the sulfide solid-state battery package.

[0007] The electrode assembly is placed in a closed environment and left to stand at the target humidity for the target time.

[0008] The hydrogen sulfide content in the enclosed environment was statically measured.

[0009] The air stability evaluation method for sulfide solid-state batteries provided in this application uses the content of hydrogen sulfide gas produced after the sulfide solid electrolyte reacts with humid air as an indicator to evaluate the air stability of the sulfide solid-state battery. This determines whether the hydrogen sulfide solid electrolyte reacts with humid air and the extent of the reaction. If the hydrogen sulfide content in the closed environment is high, it indicates that the sulfide solid electrolyte reacts severely with humid air, and the air stability of the sulfide solid-state battery is poor. Conversely, if the hydrogen sulfide content in the closed environment is low, it indicates that the reaction between the sulfide solid electrolyte and humid air is low, and the air stability of the sulfide solid-state battery is good. Therefore, the air stability of the sulfide solid-state battery can be directly reflected by the hydrogen sulfide content, providing data support for the performance evaluation of the sulfide solid-state battery.

[0010] In some embodiments, the step of placing the electrode assembly in a closed environment and allowing it to stand at a target humidity for a target time includes:

[0011] The electrode assembly is placed in a closed environment and left to stand, and moisture is introduced until the closed environment reaches the target humidity.

[0012] The gas in the enclosed environment is disturbed to allow moisture to fully contact the electrode assembly until the target time is reached.

[0013] In some embodiments, the moisture includes one or more of nitrogen, helium, and argon containing water.

[0014] In some embodiments, the oxygen content in the moisture is less than or equal to 1 ppm.

[0015] In some embodiments, the humidity difference between different areas of the enclosed environment is less than or equal to 5% RH%.

[0016] In some embodiments, the target humidity is 10%-90% RH%.

[0017] In some embodiments, the target humidity is 45%-85%RH%.

[0018] In some embodiments, the target time is 5 min to 30 min.

[0019] In some embodiments, the hydrogen sulfide content of the enclosed environment in its initial state is less than or equal to 0.5 ppm.

[0020] In some embodiments, the vacuum level of the enclosed environment in its initial state is between -101 kPa and -70 kPa.

[0021] In some embodiments, the humidity of the enclosed environment in its initial state is less than or equal to 0.03% RH.

[0022] In some embodiments, the air pressure of the enclosed environment at the target humidity is -10 kPa to 600 kPa.

[0023] In some embodiments, the step of statically determining the hydrogen sulfide content in the closed environment includes: detecting the hydrogen sulfide content once every 2 min to 10 min until the range of three consecutive tests of hydrogen sulfide content is less than 0.1 ppm, and taking the last test value as the final value. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0025] Figure 1The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0026] Figure 2 This is an exploded schematic diagram of a battery provided for some embodiments of this application.

[0027] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0028] Figure 4 This is a schematic diagram of the exploded structure of the air stability evaluation device for sulfide solid-state batteries in some embodiments of this application.

[0029] Figure 5 This is a schematic diagram of the fan compartment in the air stability evaluation device for sulfide solid-state batteries.

[0030] Figure 6 This is a schematic diagram of the material tank in the air stability evaluation device for sulfide solid-state batteries.

[0031] The accompanying drawings are not necessarily drawn to scale.

[0032] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Reception space; 6. Battery module; 7. Battery cell; 8. Evaluation device; 81. Testing chamber; 82. Chamber cover; 83. Moisture pipe; 84. Fan chamber; 85. Fan; 86. Material tank; 87. Detector; 88. Material tank flow channel; 9. Electrode assembly. Detailed Implementation

[0033] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0034] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0036] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0037] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0038] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0039] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0040] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0042] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0043] The battery device mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0044] A single battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. When there are multiple battery cells, they are connected in series, parallel, or mixed connections through a busbar.

[0045] In some embodiments, the battery device may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0046] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0047] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0048] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0049] The technical solutions described in the embodiments of this application are applicable to battery devices and electrical devices that use battery devices.

[0050] Battery devices can be used as the power source for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0051] Electrical devices can choose the type of battery device according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0052] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0053] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0054] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0055] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0056] In some embodiments, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0057] Figure 2 This is a schematic diagram of a battery explosion provided for some embodiments of this application. For example... Figure 2 As shown, the battery device 2 includes a housing 5 and battery cells (not shown), with the battery cells housed within the housing 5.

[0058] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0059] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0060] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0061] In battery device 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, in parallel, or in a mixed configuration, and then the whole assembly of multiple battery cells is housed in housing 5. Alternatively, multiple battery cells can first be connected in series, in parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a mixed configuration to form a whole assembly, which is then housed in housing 5.

[0062] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0063] like Figure 3 As shown, in some embodiments, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0064] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0065] The battery cells mentioned in the embodiments of this application may include lithium-ion battery cells or sodium-ion battery cells.

[0066] The battery cell includes an electrode assembly. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0067] Electrode assemblies generally include a positive electrode, a negative electrode, and a separator.

[0068] Solid-state batteries are batteries that use solid materials as electrolytes. A typical solid-state battery cell includes a casing and an electrode assembly within the casing. The electrode assembly generally includes a positive electrode, a negative electrode, and a solid electrolyte membrane. The solid electrolyte membrane is located between the positive and negative electrodes, serving to isolate the positive and negative electrodes and transport active ions. The solid electrolyte membrane includes a solid electrolyte, which can include one or more of the following: sulfide-based solid electrolytes, oxide-based solid electrolytes, and organic solid electrolytes.

[0069] Sulfide solid-state batteries use sulfide solid electrolytes to form solid electrolyte membranes. Because sulfide solid electrolytes are prone to deliquescence in humid air, they can fail and produce large amounts of hydrogen sulfide gas, affecting the electrochemical performance of the solid-state battery. Therefore, improving the air stability of sulfide solid-state batteries and reducing the deliquescence reaction of the sulfide solid electrolyte is one of the effective methods to improve their performance. Whether the air stability of sulfide solid-state batteries can be improved needs to be evaluated using specific methods. Currently, the air stability of sulfide solid-state batteries is generally determined by conductivity. Changes in conductivity reflect whether the sulfide solid electrolyte has undergone deliquescence or other reactions, thus determining its air stability. However, different types of sulfide solid electrolytes have significantly different conductivities, making it difficult to evaluate the air stability of all types of sulfide solid-state batteries using only conductivity.

[0070] Therefore, this application provides a method for evaluating the air stability of sulfide solid-state batteries, which can quantitatively determine the air stability of different types of sulfide solid-state electrolytes.

[0071] The air stability evaluation method for sulfide solid-state batteries provided in this application includes the following steps:

[0072] S10 offers sulfide solid-state batteries;

[0073] S20, the electrode assembly is obtained by removing the sulfide solid-state battery package;

[0074] S30, place the electrode assembly in a closed environment and leave it at the target humidity for the target time;

[0075] S40, static determination of hydrogen sulfide content in a closed environment.

[0076] The air stability evaluation method for sulfide solid-state batteries provided in this application uses the content of hydrogen sulfide gas produced after the sulfide solid electrolyte reacts with humid air as an indicator to evaluate the air stability of the sulfide solid-state battery. This determines whether the hydrogen sulfide solid electrolyte reacts with humid air and the extent of the reaction. If the hydrogen sulfide content in the closed environment is high, it indicates that the sulfide solid electrolyte reacts severely with humid air, and the air stability of the sulfide solid-state battery is poor. Conversely, if the hydrogen sulfide content in the closed environment is low, it indicates that the reaction between the sulfide solid electrolyte and humid air is low, and the air stability of the sulfide solid-state battery is good. Therefore, the air stability of the sulfide solid-state battery can be directly reflected by the hydrogen sulfide content, providing data support for the performance evaluation of the sulfide solid-state battery.

[0077] In this application, the sulfide solid battery in step S10 can be a fresh sulfide solid battery obtained through packaging, that is, a sulfide solid battery that has not undergone charge-discharge cycles after packaging. Such batteries have not undergone electrochemical reactions inside, so they can better maintain the initial characteristics of the sulfide solid electrolyte.

[0078] In this application, the sulfide solid-state battery can be a solid-state battery obtained by encapsulation under certain conditions.

[0079] In some embodiments, the step of providing a sulfide solid-state battery in step S10 may include: encapsulating the electrode assembly in an encapsulation environment to obtain a solid-state battery, wherein the encapsulation environment may be a nitrogen environment, the water content may be less than or equal to 1 ppm, and the oxygen content may be less than or equal to 1 ppm. By limiting the water and oxygen content in the encapsulation environment, the impact of the encapsulation process on the performance of the sulfide solid-state battery can be effectively reduced, thereby reducing the impact on the air stability evaluation results.

[0080] In some embodiments, step S30, which involves placing the electrode assembly in a closed environment and allowing it to stand at a target humidity for a target time, may include: placing the electrode assembly in a closed environment to achieve the target humidity, and allowing the sulfide solid electrolyte in the electrode assembly to react with water within the target time.

[0081] In some embodiments, step S30 may include:

[0082] S31, Place the electrode assembly in a closed environment and let it stand, then introduce moisture until the closed environment reaches the target humidity;

[0083] S32, disturbs the gas in the enclosed environment, allowing moisture to fully contact the electrode assembly until the target time is reached.

[0084] In this application, a closed environment refers to an environmental space that is not connected to the outside atmosphere, and the parameters (humidity, temperature, and gas composition, etc.) in the closed environment can be freely adjusted. This can reduce the influence of the external environment on the test results.

[0085] In some implementations, a closed environment can be provided by Figure 4 The apparatus shown is configured for evaluating the air stability of sulfide solid-state batteries. (Refer to...) Figure 4 The evaluation device may include a detection chamber 81 and a cover 82. The detection chamber 81 has an inner cavity for accommodating the electrode assembly 9. The cover 82 is used to seal the inner cavity of the detection chamber, thus isolating the interior of the detection chamber 81 from the external atmospheric environment to form a closed environment. A moisture pipe 83 is provided on the cover 82, which communicates with the inner cavity of the detection chamber 81 to introduce moisture into the detection chamber 81.

[0086] In some embodiments, refer to Figure 4 The evaluation device may also include a fan 85 chamber 84 disposed in the detection chamber 81, wherein a fan 85 is disposed in the fan 85 chamber 84, and the fan 85 rotates to disturb the air in the detection chamber 81, thereby allowing the moisture in the detection chamber 81 to better contact the electrode assembly 9.

[0087] In some embodiments, refer to Figure 5 The detection chamber 81 is equipped with a material tank 86 for fixing the electrode assembly 9 and a detector 87 for detecting the concentration of hydrogen sulfide gas; refer to Figure 6 Multiple material channels 88 are provided on the material trough 86, and the moisture entering the detection chamber 81 can flow through the material channels 88 and fully contact the electrode assembly 9.

[0088] In this embodiment of the application, when evaluating the air stability of sulfide solid-state batteries, the electrode assembly is placed in the material tank inside the test chamber and left to stand. Then, the chamber cover is closed, and moisture is introduced into the inner cavity of the test chamber through the moisture channel until the target humidity is reached. Then, the fan is turned on to agitate the moisture so that it can fully contact the electrode assembly. After the target time is reached, the fan is turned off, and the concentration of hydrogen sulfide gas in the test chamber is measured.

[0089] In some embodiments, moisture may include one or more of nitrogen, helium, and argon containing water.

[0090] In some embodiments, the oxygen content in the moisture may be less than or equal to 1 ppm. By limiting the oxygen content in the moisture to the above range, the reaction between oxygen and the sulfide solid electrolyte can be reduced, thereby reducing the impact on the measurement results and improving the accuracy of the evaluation results.

[0091] In some embodiments, the target humidity can be from 10RH% to 90RH%. Exemplarily, the target humidity can be 10RH%, 15RH%, 20RH%, 25RH%, 30RH%, 35RH%, 40RH%, 45RH%, 50RH%, 55RH%, 60RH%, 65RH%, 70RH%, 75RH%, 80RH%, 85RH%, 90RH%, or any range of the above values. Optionally, the target humidity can be from 45RH% to 85RH%.

[0092] By limiting the target humidity to the above range, sufficient contact can be made between the sulfide solid electrolyte in the electrode assembly and the moisture in the air.

[0093] In some embodiments, the air pressure of the enclosed environment at the target humidity can be from -10 kPa to 600 kPa.

[0094] In some embodiments, the humidity difference between different areas in an enclosed environment may be less than or equal to 5% RH%.

[0095] The fan's agitation can make the moisture distribution in the enclosed environment more uniform, and the humidity in different locations in the enclosed environment is more similar. This allows the sulfide solid electrolyte in the electrode assembly to come into more sufficient contact with the moisture, thereby improving the stability of the evaluation results.

[0096] In this embodiment of the application, the difference in humidity between different areas of the enclosed environment can be measured using methods known in the art. For example, humidity detectors can be set in different areas of the enclosed environment, such as the upper, middle, and bottom of the detection chamber, and the humidity values ​​in the upper, middle, and bottom of the detection chamber can be measured respectively to obtain the difference in data from each location.

[0097] In some embodiments, the target time can be 5 min to 30 min. For example, the target time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, or any range of the above values.

[0098] In some embodiments, the enclosed environment inside the detection chamber can be evacuated before moisture is introduced, so that the enclosed environment has a suitable initial state.

[0099] In some embodiments, the hydrogen sulfide content in the enclosed environment in its initial state is less than or equal to 0.5 ppm.

[0100] In some embodiments, the vacuum level of the enclosed environment in its initial state is between -101 kPa and -70 kPa.

[0101] In some embodiments, the humidity of the enclosed environment in its initial state is less than or equal to 0.03% RH.

[0102] By controlling the initial state of the target environment to meet the above conditions, the impact of environmental factors on the test results can be further reduced, and the accuracy of the evaluation results can be improved.

[0103] In some embodiments, step S40, the step of statically determining the hydrogen sulfide content in a closed environment, includes: detecting the hydrogen sulfide content once every 2 min to 10 min until the range of three consecutive tests of hydrogen sulfide content is less than 0.1 ppm, and taking the last test value as the final value.

[0104] In this embodiment, static measurement refers to measuring after the fan is turned off, air disturbance is stopped, and the environment has returned to static stability in a closed environment. This allows for more accurate measurement results. By continuously detecting and calculating the range of each measurement result, errors can be reduced, making the evaluation results more accurate.

[0105] [Positive electrode plate]

[0106] In some embodiments, the positive electrode includes a positive current collector and a positive film layer located on at least one surface of the positive current collector.

[0107] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0108] In some embodiments, the positive electrode active material includes one or more of lithium phosphate, layered lithium transition metal oxide, Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide.

[0109] If the positive electrode active material is one or more of lithium phosphate and layered lithium transition metal oxide, then the positive electrode active material can be used in lithium-ion battery cells; if the positive electrode active material is one or more of Prussian blue compounds, polyanionic compounds, and sodium transition metal oxide, then the positive electrode material can be used in sodium-ion battery cells.

[0110] Lithium-containing phosphates may include one or more of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.

[0111] Examples of layered lithium-containing transition metal oxides may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds.

[0112] In some embodiments, the layered lithium-containing transition metal oxide may include Ni. The molar amount of Ni may account for more than 70% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; optionally, the molar amount of Ni may account for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide; more preferably, the molar amount of Ni may account for more than 90% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0113] The higher the Ni content in layered lithium-containing transition metal oxides, the higher the energy density of the battery cell.

[0114] In some embodiments, layered lithium-containing transition metal oxides may include Li a Ni b Co c M d O e A f Wherein, 0 < a ≤ 1.2; 0.8 ≤ b < 1; 0 < c < 1; 0 < d < 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1; M includes, but is not limited to, one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B; A includes, but is not limited to, one or more of N, F, S, and Cl. This can further improve the energy density of individual battery cells.

[0115] In some embodiments, as an example, layered lithium-containing transition metal oxides may include, but are not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.06 Mn 0.04 O2, LiNi 0.92 Co 0.06 Mn 0.02 O2, LiNi 0.96 Co 0.02 Mn 0.02 One or more of O2.

[0116] During the charging and discharging process of a battery cell, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar Li content may change when the positive electrode active material is applied to the battery cell.

[0117] In some embodiments, as an example, sodium transition metal oxides may include, but are not limited to:

[0118] Na 1-x Cu h Fe k Mn l M 1 m O 2-y M 1 It is one or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn, and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0119] Na 0.67 Mn 0.7 Ni z M 2 0.3-z O2, where M 2 It is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 <z≤0.1;

[0120] Na a Li b Ni c Mn d Fe e O2, of which 0.67 <a≤1,0<b<0.2,0<c<0.3,

[0121] 0.67 <d+e<0.8,b+c+d+e=1。

[0122] In some embodiments, as an example, the polyanionic compound may include, but is not limited to:

[0123] A 1 f M 3 g (PO4) i O j X 1 3-j, where A is one or more of H, Li, Na, K, and NH₄, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, 0 ≤ j ≤ 2;

[0124] Na n M 4 PO₄X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, 0 < n ≤ 2;

[0125] Na p M 5 q (SO₄)₃, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, 0 < q ≤ 2;

[0126] Na s Mn t Fe 3-t (PO₄)₂(P₂O₇), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example t is 0, 1, 1.5, 2, or 3.

[0127] In some embodiments, by way of example, Prussian blue compounds may include but are not limited to:

[0128] A u M 6 v [M 7 (CN)₆] w ·xH₂O, where A is H + , NH₄ + , an alkali metal cation, and an alkaline earth metal cation, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + , Li + , Na + , K + , NH₄ + , Rb + , Cs + , Fr + , Be 2+ , Mg 2+ , Ca 2+ , Sr2+ Ba 2+ and Ra 2+ One or more of them, M 6 and M 7 Each is an independently selected cation of one or more transition metal elements chosen from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W. Optionally, A is Li. + Na + and K + One or more of them, M 6 It is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni, and Cu, M 7 It is a cation of one or more transition metal elements selected from Mn, Fe, Co, Ni and Cu.

[0129] In the examples of positive electrode active materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause the molar content of O to change, and the actual molar content of O will fluctuate.

[0130] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0131] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0132] In some implementations, the weight percentage of the binder in the positive electrode film layer is greater than or equal to 0.5%, which is beneficial for obtaining good adhesion performance.

[0133] In some embodiments, the positive electrode film layer further includes a conductive agent. As an example, 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.

[0134] In some embodiments, the positive 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 substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be made by forming a metal material, such as aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, on the polymer substrate. The polymer substrate may include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and other substrates.

[0135] In some embodiments, the thickness of the positive current collector is from 4 μm to 20 μm. It is optionally from 6 μm to 18 μm, and more preferably from 8 μm to 16 μm.

[0136] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0137] [Negative electrode plate]

[0138] In some embodiments, the negative electrode film layer comprises a negative electrode active material.

[0139] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector can be made of materials such as metal foil, carbon-coated metal foil, or porous metal plate, and copper foil is optional.

[0140] As an example, the negative electrode active material may include one or more of the following: artificial graphite, natural graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, and silicon-carbon composites.

[0141] Silicon-based composite materials can be prepared by methods known in the art. For example, they can be prepared by vapor deposition using graphite and silicon materials as raw materials.

[0142] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0143] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0144] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0145] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one side of the polymeric material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymeric material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0146] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer sandwiched between the negative electrode current collector and the negative electrode film layer and located on the surface of the negative electrode current collector, which may be composed of a conductive agent and a binder; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0147] The negative electrode sheet can be prepared as follows: The negative electrode active material, negative electrode binder, negative electrode conductive agent, and optional other additives are dispersed in a solvent and stirred evenly to form a negative electrode slurry; the negative electrode slurry is coated onto a negative electrode current collector, and after drying, rolling, and other processes, a negative electrode sheet is formed. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0148] [Solid electrolyte membrane]

[0149] Solid electrolyte membranes include solid electrolytes, which may include sulfide-based solid electrolytes.

[0150] Sulfide solid electrolytes have high 10 -2 S / cm to 10 -3 A lithium-ion conductivity of S / cm facilitates the formation of contact interfaces between electrodes and exhibits high mechanical strength and flexibility. In this application embodiment, there are no particular limitations on the type of sulfide-based solid electrolyte, and all known sulfide materials used in the battery field are acceptable. In this application embodiment, the sulfide-based solid electrolyte may include Li6PS5Cl (LPSCl), Thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S11 , LiI-Li2S-B2S3, Li3PO4-Li2S-Si2S, Li3PO4-Li2S-SiS2, LiPO4-Li2S-SiS, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and Li7P3S 11 One or more of them.

[0151] In some embodiments, the solid electrolyte may also include one or more of oxide solid electrolytes and organic solid electrolytes.

[0152] Oxide-based solid electrolytes exhibit high safety in air and have a 10 -3 S / cm to 10 -4 The lithium-ion conductivity (S / cm) is lower than that of sulfide-based solid electrolytes, but relatively higher. Furthermore, oxide-based solid electrolytes exhibit high electrochemical safety and mechanical strength. However, oxide-based solid electrolytes have high oxidation voltage. Additionally, solid electrolytes have high grain boundary resistance, making it difficult to form a contact interface between the electrode and electrolyte, requiring high-temperature heat treatment processes of 1000°C or higher, and these processes are difficult to scale up. In the embodiments of this application, the oxide-based solid electrolyte can be any known oxide material used in the field of lithium batteries. In the embodiments of this application, the oxide-based solid electrolyte includes perovskite solid electrolyte, sodium superionic conductor solid electrolyte (NASICON), lithium superionic conductor solid electrolyte (LISICON), and lithium lanthanum zirconium oxide solid electrolyte (LLZO).

[0153] Organic solid electrolytes (OSEs) are a type of solid electrolyte. OSEs can readily form electrode interfaces and minimize dendrite growth, thus ensuring stable reactions between OSEs and lithium metal. The disadvantages of OSEs are their relatively low lithium-ion conductivity and the fact that they typically require high-temperature operation. In this embodiment, the OSE comprises polyethylene oxide (PEO).

[0154] The thickness of the solid electrolyte membrane can be selected differently depending on the properties of the desired all-solid-state battery. Specifically, in some embodiments, the thickness of the solid electrolyte membrane can be from 0.1 μm to 1000 μm; in other embodiments, the thickness of the solid electrolyte membrane can be from 1 μm to 500 μm; in still other embodiments, the thickness of the solid electrolyte membrane can be from 20 μm to 30 μm; this application does not limit it in this regard.

[0155] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for evaluating the air stability of sulfide solid-state batteries, characterized in that, Includes the following steps: Provides sulfide solid-state batteries; The electrode assembly is obtained by removing the sulfide solid-state battery package. The electrode assembly is placed in a closed environment and left to stand at the target humidity for the target time. The hydrogen sulfide content in the enclosed environment was statically measured.

2. The method according to claim 1, characterized in that, The step of placing the electrode assembly in a closed environment and allowing it to stand at a target humidity for a target time includes: The electrode assembly is placed in a closed environment and left to stand, and moisture is introduced until the closed environment reaches the target humidity. The gas in the enclosed environment is disturbed to allow moisture to fully contact the electrode assembly until the target time is reached.

3. The method according to claim 2, characterized in that, The moisture includes one or more of nitrogen, helium, and argon containing water.

4. The method according to claim 2 or 3, characterized in that, The oxygen content in the moisture is less than or equal to 1 ppm.

5. The method according to any one of claims 2 to 4, characterized in that, The humidity difference between different areas in the enclosed environment is less than or equal to 5% RH%.

6. The method according to any one of claims 1 to 5, characterized in that, The target humidity is 10%-90%RH%.

7. The method according to claim 6, characterized in that, The target humidity is 45%-85%RH%.

8. The method according to any one of claims 1 to 7, characterized in that, The target time is 5 min-30 min.

9. The method according to any one of claims 1 to 8, characterized in that, The enclosed environment satisfies at least one of the following conditions: (1) The hydrogen sulfide content of the enclosed environment in the initial state is less than or equal to 0.5 ppm; (2) The vacuum degree of the enclosed environment in the initial state is -101kPa to -70kPa; (3) The humidity of the enclosed environment in its initial state is less than or equal to 0.03RH%. (3) The air pressure of the enclosed environment at the target humidity is -10 kPa to 600 kPa.

10. The method according to any one of claims 1 to 9, characterized in that, The steps for statically determining the hydrogen sulfide content in the closed environment include: measuring the hydrogen sulfide content once every 2-10 minutes until the range of three consecutive tests of hydrogen sulfide content is less than 0.1 ppm, and taking the last test value as the final value.

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