Gas sensing material and preparation method thereof, sensor, battery and electric equipment

Abstract

The invention discloses a gas sensing material and a preparation method thereof, a sensor, a battery and electric equipment. Wherein the gas sensing material comprises an M / MXene composite material, and the M / MXene composite material comprises a metal (M) single atom and an MXene material; and / or the M / MXene composite material comprises a metal (M) cluster and an MXene material. The gas sensing material provided by the invention can realize detection of target gas in an oxygen-free or low-oxygen environment, and can realize detection of gas produced in a battery. Furthermore, the sensitivity and selectivity of gas detection can be improved, the response and recovery speed is accelerated, and the detection limit of gas is reduced.

Description

Technical Field

[0001] This application relates to the field of new energy technologies, and particularly to gas sensing materials and their preparation methods, sensors, batteries, and electrical equipment. Background Art

[0002] With the continuous exacerbation of global energy and environmental problems, new energy, as one of the fields of sustainable development, is developing rapidly. Batteries are being used more and more widely as a new energy source. Among them, the problem of gas production in batteries has always been a concern. The gases generated by batteries are prone to cause safety problems such as explosions and fires. By detecting the gas conditions inside the battery, early warnings can be given in a timely manner. The sensing principle of existing gas sensors generally requires oxygen, which limits their application in detecting gases under anaerobic conditions. However, most of the inside of a battery monomer is an anaerobic or low-oxygen environment. Therefore, there is an urgent need to develop new materials and sensors that can respond to gases under non-oxygen conditions. The above statements are only used to provide background technical information related to this application, and do not necessarily constitute prior art. Summary of the Invention

[0003] The main technical problem to be solved by this application is to provide a gas sensing material and its preparation method, sensor, battery, and electrical equipment that can achieve gas detection in an anaerobic or low-oxygen environment.

[0004] To solve the above technical problem, a technical solution adopted by this application is: to provide a gas sensing material, including an M / MXene composite material. The composite material includes metal (M) single atoms and MXene material, or in other words, in the M / MXene composite material, metal M is combined with the MXene material in the form of single atoms; and / or the M / MXene composite material includes metal (M) clusters and MXene material, or in other words, in the M / MXene composite material, metal M is combined with the MXene material in the form of clusters. This gas sensing material is a chemiresistive sensing material, which relies on the change in conductivity when the gas sensing material adsorbs and desorbs gases to achieve the detection purpose, enabling the gas sensing material to detect gases in an anaerobic or low-oxygen environment.

[0005] Furthermore, due to the tunability of the electronic structure of metal M and the exposure of active sites, it can serve as a reaction center for binding with gas molecules, accelerating the charge transfer rate between the gas molecules and the M / MXene composite material, increasing the active sites for gas-solid surface reactions, improving the response sensitivity of the gas sensing material, reducing the detection limit, enhancing the selectivity, and enabling rapid response and recovery.

[0006] In one embodiment, the M / MXene composite material includes a metal (M) carbonitride, and the metal carbonitride is loaded on the surface of the MXene material. Or, in the M / MXene composite material, the metal M is loaded on the surface of the MXene material in the form of a metal carbonitride. With this arrangement, a strong interaction can be formed between the metal M and the carrier (MXene). Therefore, the metal M can be stably fixed on the surface of the MXene material to form a stable M / MXene composite material.

[0007] In one embodiment, each metal atom M in the metal carbonitride is bonded to four nitrogen atoms respectively. With this arrangement, the metal carbonitride has the electronic structure characteristics of noble metals, can form an interfacial confinement structure with MXene, and enhance the sensing performance through the electron spillover effect, making the composite material have a higher active sensing performance, high sensitivity, good selectivity, and a simple preparation process.

[0008] In one embodiment, the metal carbonitride includes a graphite structure, and the nitrogen atoms bonded with metal atoms are embedded in the graphite layer and bonded to the carbon atoms of the graphite layer, and the graphite is combined on the surface of the MXene material. Or, the carbon atoms in the metal carbonitride exist in the form of graphite, the nitrogen atoms bonded with metal atoms are embedded in the graphite layer and bonded to the carbon atoms of the graphite layer, and the graphite is combined on the surface of the MXene material. By using the graphite layer as the carbon material carrier, a connection skeleton can be provided for the metal groups, enabling the metal groups to be loaded. The hierarchical pore structure of the graphite layer can also provide more binding sites for gas molecules, increasing the sites where gas binding reactions occur.

[0009] In one embodiment, the metal carbonitride is doped with element X, and X includes one or more of sulfur, phosphorus, and boron. Due to the difference in electronegativity of the doping elements, the conductivity and gas adsorption characteristics of the gas sensing material can be adjusted by doping.

[0010] In one embodiment, each metal atom M in the metal carbonitride is bonded to four nitrogen atoms respectively, and one or more of the four nitrogen atoms bonded to the metal atom M are replaced by the doped element X. With this arrangement, the structure of the central metal atom can be optimized, thereby improving the sensitivity, selectivity, and stability of the sensor.

[0011] In one embodiment, the metal (M) single atoms in the M / MXene composite material are embedded in the structure of the MXene material; that is to say, the metal M in the M / MXene composite material is embedded in the structure of the MXene material in the form of single atoms. Through this setting, the metal M is pinned at the defect sites of MXene in the form of single atoms, which is conducive to the existence of the metal in the form of single atoms and not easy to agglomerate. The active sites exist at the atomic level, and the quantum effect can be exerted, with the characteristics of high sensitivity and high selectivity.

[0012] In one embodiment, the metal M includes one or more of Fe, Co, Ni, Mn, Cu, Zn, Cr, Pd, Pt, Au, Ag, Ir, Ru; optionally, the metal M includes one or more of Fe, Co, Ni. By selecting different metals M, the response sensitivity and selectivity of gas sensing can be regulated.

[0013] In one embodiment, the size of the metal single atoms in the M / MXene composite material is less than 1 nm; and / or the size of the metal clusters in the M / MXene composite material is 1 - 50 nm. By setting the sizes of the metal single atoms and metal clusters within the nanoscale range, it is beneficial to increase the adsorption sites, improve the activity of the adsorption sites, enhance the efficiency of binding with gas molecules, and improve the sensitivity of the gas sensing material.

[0014] In one embodiment, based on the total number of atoms in the M / MXene composite material, the atomic content (at%) of the metal M element is less than or equal to 15%; optionally, the atomic content (at%) of the metal M element is less than or equal to 10%; optionally, the atomic content (at%) of the M element is less than or equal to 5%. By selecting the atomic content of the M element, the sensitivity and selectivity of the gas sensing material can be adjusted, and a trade-off can be made between sensitivity priority or selectivity priority according to different application scenarios to meet the requirements of specific applications.

[0015] In one embodiment, the MXene material includes M’ n+1 X’ n T x , where M’ is an early transition metal element, X’ n is carbon or nitrogen element, and T x is any one of the OH - 、O 2- 、F - groups. By selecting the MXene material as the substrate of the composite material, a broad binding site can be provided for the metal M, and a large number of surface functional groups of the MXene material can provide rich active sites for gas adsorption and surface reactions.

[0016] In one embodiment, the response gases of the gas sensing material include CO, NO 2 , NO, H 2 , CH 4 , H 2 S, ethylene, ethane, one or more of volatile organic compounds, volatile electrolytes; optionally, the volatile organic compound includes any one of methanol, formaldehyde, toluene, styrene, phenol, benzene; optionally, the volatile electrolyte includes any one of polyether electrolytes, polyester electrolytes. By responding to the above gases, the gas sensing material can adaptively meet different gas detection requirements, thereby expanding the application range of the gas sensing material.

[0017] In one embodiment, the gas sensing material has a sensing response to gases in the range of -55°C to 65°C. In this case, the gas sensing material can adapt to the operating temperatures of most batteries, reduce the problem of gas sensing material failure caused by environmental temperature, and is beneficial for the gas sensing material to adapt to different working environments.

[0018] To solve the above technical problems, another technical solution adopted in this application is: to provide a preparation method of a gas sensing material, including: providing a composite of MXene and a metal-organic complex, where the metal-organic complex is a complex of metal M and an organic ligand; calcining the composite to obtain an M / MXene composite material, in which metal M in the M / MXene composite material is combined with the MXene material in the form of single atoms; and / or metal M in the M / MXene composite material is combined with the MXene material in the form of clusters. The gas sensing material prepared by the above method can perform gas detection in an anaerobic or low-oxygen environment.

[0019] In one embodiment, the calcining of the composite includes: the calcining temperature is 700 - 1000°C, preferably 850 - 950°C; and / or the calcining time is 1 - 4 h. Within this temperature and time range, the organic component in the metal-organic complex can undergo pyrolytic carbonization to form porous carbon with a graphite phase structure, and at the same time, some metal ions in the metal-organic complex framework volatilize at high temperature to form defects and active sites.

[0020] In one embodiment, the calcining of the composite includes: calcining the composite in an inert gas atmosphere, optionally, the inert gas includes one or more of argon, hydrogen, nitrogen. By introducing an inert gas in the calcining step, it is beneficial to reduce the oxidation reaction during the reaction, protect the activity of the surface active sites of the material, and improve the product quality.

[0021] In one embodiment, the composite is calcined in a doping gas atmosphere. Optionally, the doping gas includes one or more of ammonia gas and hydrogen sulfide. While providing protection for the reaction, doping elements can also be introduced to optimize the sensing performance of the gas sensing material and enhance its adaptability to different application requirements.

[0022] In one embodiment, providing the composite of MXene and metal-organic complex includes: mixing the metal-organic complex solution with the MXene solution, and stirring and reacting to obtain the composite. Through the above reaction, the composite of MXene and metal-organic complex is prepared, which is the precursor of the M / MXene composite material and the prerequisite for finally obtaining the M / MXene composite material.

[0023] In one embodiment, mixing the metal-organic complex solution with the MXene solution includes: dropping the MXene solution into the stirred metal-organic complex solution; optionally, the dropping rate of the MXene solution is 1 - 20 drops per second. The stirring state is conducive to the full contact between the MXene solution and the metal-organic complex solution, accelerating the reaction rate; by controlling the dropping rate, the local solution concentration of the reaction can be adjusted, which is conducive to the formation of well-dispersed and uniform-sized crystals.

[0024] In one embodiment, before mixing the metal-organic complex solution with the MXene solution includes: combining the metal-organic complex with a surfactant; and / or combining the MXene material with a surfactant. By combining a surfactant in the metal-organic complex or MXene, it is beneficial to improve the interfacial affinity between the metal-organic complex and MXene, promoting a more effective reaction; in addition, it is beneficial to the uniform dispersion of the metal-organic complex and MXene in the solution, thus facilitating the uniformity and stability of the reaction.

[0025] In one embodiment, the surfactant includes cetyltrimethylammonium bromide. By using cetyltrimethylammonium bromide as the surfactant, it is beneficial to the combination of the metal-organic complex and MXene. At the same time, the positive ion part of cetyltrimethylammonium bromide can attract the negative charge functional groups (such as -OH, -F) on MXene and the negative charges on the surface of the metal-organic complex, thus being conducive to improving the stability of the connection.

[0026] In one embodiment, combining the metal-organic complex with the surfactant includes: providing a metal-organic complex precursor and cetyltrimethylammonium bromide; mixing and reacting the metal-organic complex precursor and cetyltrimethylammonium bromide to obtain a metal-organic complex combined with cetyltrimethylammonium bromide. The positive ion part of cetyltrimethylammonium bromide can be attracted to the surface negative charge of the metal-organic complex to form an adsorption layer, and the hydrophobic alkyl chain of cetyltrimethylammonium bromide can interact with the hydrophobic region of the metal-organic complex, thereby further stabilizing the adsorption layer; this binding method can help disperse and stabilize the metal-organic complex and regulate its properties.

[0027] In one embodiment, doping and modifying the metal-organic complex includes: providing a metal-organic complex precursor and a doping precursor; mixing and reacting the metal-organic complex precursor and the doping precursor to obtain a doped and modified metal-organic complex. Through this setting, the doping purpose can be effectively achieved, doping of multiple elements can be realized, and thus the gas sensing material can be modified purposefully to broaden the application range of the gas sensing material.

[0028] To solve the above technical problems, another technical solution adopted by this application is: providing a gas sensor, which includes the gas sensing material of any one of the above; or includes the gas sensing material prepared by any one of the above methods. Through the above setting, gas detection can be carried out in an anaerobic or low-oxygen environment.

[0029] To solve the above technical problems, another technical solution adopted by this application is: providing a battery, and the battery includes the gas sensor of any one of the above. Through the above setting, the detection of gas in the battery monomer can be realized.

[0030] To solve the above technical problems, another technical solution adopted by this application is: providing an electrical device, including the above battery. The electrical device has at least the same advantages as the battery.

[0031] The above description is only an overview of the technical solution of this application. In order to be able to understand the technical means of this application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of this application more obvious and understandable, the specific embodiments of this application are specifically given below. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images of gas sensing materials according to one or more embodiments;

[0034] Figure 2 Transmission electron microscopy (TEM) images of gas sensing materials according to one or more embodiments;

[0035] Figure 3 Energy-dispersive spectroscopy (EDS) images of high-angle annular dark-field scanning transmission electron microscopy of gas sensing materials according to one or more embodiments;

[0036] Figure 4 Synchrotron radiation X-ray absorption spectroscopy (XAFS) diagrams of gas sensing materials according to one or more embodiments;

[0037] Figure 5 Synchrotron radiation X-ray absorption spectroscopy (XAFS) of gas sensing materials according to one or more embodiments;

[0038] Figure 6 Synchrotron radiation X-ray absorption spectroscopy (XAFS) diagrams of gas sensing materials according to one or more embodiments;

[0039] Figure 7 X-ray diffraction images (XRD) of gas sensing materials according to one or more embodiments;

[0040] Figure 8 Reaction schematic diagrams prepared from gas sensing materials according to one or more embodiments;

[0041] Figure 9 Schematic diagrams of gas sensing performance tests according to one or more embodiments;

[0042] Figure 10 Gas response schematic diagrams of the gas sensing material Ni / MXene according to one or more embodiments;

[0043] Figure 11 Gas response schematic diagrams of the gas sensing material Ni / MXene according to one or more embodiments;

[0044] Figure 12 Gas response schematic diagrams of the gas sensing material Ni / MXene according to one or more embodiments;

[0045] Figure 13 Gas response schematic diagrams of the gas sensing material Ni / MXene according to one or more embodiments;

[0046] Figure 14 Schematic diagram of gas response of gas sensing material Fe / MXene according to one or more embodiments;

[0047] Figure 15 Schematic diagram of gas response of gas sensing material Co / MXene according to one or more embodiments;

[0048] Figure 16 Schematic diagram of gas response of gas sensing material Ni / MXene according to one or more embodiments;

[0049] Figure 17 Schematic diagram of exploded structure of a battery according to one or more embodiments;

[0050] Figure 18 Schematic diagram of exploded structure of a battery cell according to one or more embodiments;

[0051] Figure 19 Schematic diagram of the structure of a vehicle according to one or more embodiments.

[0052] In the drawings:

[0053] 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, box body; 11, first part; 12, second part; 20, battery cell; 21, end cover; 21a, electrode terminal; 22, housing; 23, electrode assembly. Detailed implementation manners

[0054] To make the objectives, technical solutions and effects of this application clearer and more definite, the following will describe in detail the embodiments of the technical solutions of this application with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of this application more clearly, so they are only examples and cannot be used to limit the protection scope of this application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein 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 specification and claims of this application and the above accompanying drawings are intended to cover non-exclusive inclusion.

[0056] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces), unless otherwise specifically defined.

[0057] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and is not necessarily meant to refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0058] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0059] Quantities, ratios, and other numerical values are presented herein in a range format. It should be understood that such range formats are for convenience and brevity, and should be understood flexibly, including not only the numerical values explicitly specified as range limits, but also all individual numerical values or sub-ranges subsumed within the stated range, as if each numerical value and sub-range were explicitly specified.

[0060] If there is no special indication, all steps of the present application can be carried out sequentially, randomly, or in parallel, and preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) carried out sequentially, or steps (b) and (a) carried out sequentially, or steps (a) and (b) carried out in parallel simultaneously. For example, it is mentioned that the method may further include step (c), indicating that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0061] Batteries are widely used in the new energy field, mainly including electric vehicles, energy storage systems, and renewable energy. In the field of electric vehicles, lithium-ion batteries are the mainstream technology. Their high energy density, long lifespan, and fast charging characteristics enable electric vehicles to achieve longer driving ranges and higher performance. In terms of energy storage systems, batteries are widely used for large-scale and distributed energy storage. They can balance the power grid load, store renewable energy such as solar and wind energy, and release the stored energy during peak periods. In addition, small rechargeable batteries are also widely adopted in applications such as wearable devices, drones, and smart homes. The development of battery technology aims to improve energy density, extend lifespan, reduce costs, and focus on environmental friendliness. With the growing demand for clean energy and sustainable development, the application of batteries in the new energy field will continue to expand and drive the further development of the energy transition.

[0062] During the charge and discharge process of the battery, some side reactions will generate gases. If the gases generated by the battery are not discharged in time, it will lead to an increase in the internal pressure of the battery, exceeding the normal level. Excessive internal pressure will have a negative impact on the performance and appearance of the battery. For example, in severe cases, it will have a destructive impact on the performance and appearance of the battery, such as leakage, bulging, an increase in the internal resistance of the battery, a shorter discharge time, and a shorter cycle life. In addition, there are some abnormal operations during the use of the battery, including overcharging, over-discharging, internal faults, etc. In this case, the chemical reactions inside the battery may get out of control, accompanied by a violent release of gases, and even trigger battery thermal runaway. Battery thermal runaway refers to a chain reaction phenomenon triggered by various inducements. The large amount of heat and harmful gases emitted during thermal runaway can cause the battery to catch fire and explode.

[0063] In order to monitor the gas production of the battery in a timely manner, it has been found that gas sensors can be installed inside the battery. Specifically, characteristic gases are generated when the battery is working or in thermal runaway. For example, ethylene carbonate, a component of the electrolyte in a lithium battery, will produce carbon monoxide and carbon dioxide during oxidation decomposition on the positive electrode side, and carbon monoxide and methane during reduction reaction on the negative electrode side. By detecting the characteristic gases exceeding the concentration threshold and issuing an alarm in a timely manner, measures can be taken in the initial stage when the internal pressure of the battery exceeds the normal level, reducing the occurrence of safety accidents. However, existing gas sensors have defects in the detection of battery gas production. For example, for electrochemical sensors, because their working principle is based on reversible oxidation-reduction reactions, they must be used in an oxygen-containing environment. In the actual scenario of battery gas detection, the inside of the battery is generally oxygen-free or low-oxygen, restricting the application of this type of gas sensor. Another example is infrared sensors. Their working process does not depend on oxygen, but the detection sensitivity for low-concentration gases needs to be improved.

[0064] Based on the above considerations, in order to solve the problems of gas generation monitoring in batteries relying on oxygen and low sensitivity in detecting low-concentration gases, the present application designs a gas sensing material. By combining metal element M in the form of single atoms or clusters with MXene material, an M / MXene composite material is prepared. This gas sensing material is a chemiresistive sensing material, which relies on the change in conductivity during the adsorption and desorption of gas by the gas sensing material to achieve the detection purpose, enabling the gas sensing material to respond to one or more gases including carbon monoxide (CO), nitrogen dioxide (NO 2 ), nitric oxide (NO), hydrogen (H 2 ), methane (CH 4 ), hydrogen sulfide (H 2 S), ethylene, ethane, volatile organic compounds, and volatile electrolytes in an anaerobic or hypoxic environment.

[0065] According to some embodiments of the present application, the present application discloses a gas sensing material, which is an M / MXene composite material. In the M / MXene composite material, metal M is combined with MXene material in the form of single atoms; and / or metal M is combined with MXene material in the form of clusters. That is, all metal M in the M / MXene composite material can exist in the form of single atoms, or all metal M in the M / MXene composite material can exist in the form of clusters, or some metal M in the M / MXene composite material exists in the form of single atoms and some metal M exists in the form of clusters. The gas sensing material can be one or a mixture of multiple such M / MXene composite materials.

[0066] Among them, the MXene material includes M’ n+1 X’ n T x , where M’ is an early transition metal element, X’ is carbon or nitrogen element, and T x is any one of hydroxyl (OH - ), oxygen anion (O 2- ), and fluoride ion (F - ) groups.

[0067] Among them, n = 1 - 3, and the early transition metal elements include titanium (Ti), zirconium (Zr), vanadium (V), molybdenum (Mo), etc., and T xRepresent surface functional groups. MXene materials are a class of two-dimensional inorganic compounds composed of transition metal carbides, nitrides, or carbonitrides with a thickness of several atomic layers. MXene is usually prepared by selectively etching the A-layer element from the MAX phase as a precursor through solution or molten salt method. The MAX phase is a class of ternary layered compounds, where M in the MAX phase represents a transition metal element, A represents elements in Group IIIA or IVA such as aluminum (Al), silicon (Si), tin (Sn), etc., and X represents carbon or nitrogen. Due to its graphene-like two-dimensional layered structure, MXene exhibits advantages such as a high specific surface area, excellent electrical conductivity, and stable mechanical properties. MXene can be Ti 3 C 2 T x 、Ti 2 CT x 、Nb 2 CT x 、Ti 3 CNT x 、TiVCT x and so on.

[0068] By selecting MXene materials as the substrate of the composite material, the extremely high specific surface area and excellent electrical conductivity characteristics of the MXene matrix, as well as the abundant active sites on the MXene surface, can be utilized to provide a broad binding site for metal M; at the same time, a large number of surface functional groups of the MXene material can provide abundant active sites for gas adsorption and surface reactions.

[0069] The composite of metal M with MXene materials in the form of single atoms means that the metal is loaded on the surface of the carrier (MXene) in the form of single atoms, or pinned and embedded inside the carrier (MXene) in the form of single atoms. It can be connected to the surface of the carrier (MXene) through a bonding method with heteroatoms, or pinned at the defect sites of the carrier (MXene).

[0070] Please refer to Figure 1 , Figure 1 for the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images of the gas sensing material according to one or more embodiments. Figure 1 It shows that metal atoms exist in a monodispersed state, and bright isolated metal single-atom dots are shown in the figure. In this composite material, the metal component is reduced to the single-atom scale, and the size of the metal single atoms can be less than 1 nm; it has the characteristics of maximizing atomic utilization and isolating active sites, which can increase the adsorption sites and the adsorption area, thereby improving the gas response sensitivity and reducing the response time. Further, when the size of the active sites is reduced to the single-atom size, the quantum effect can be exerted, and it has the characteristics of high sensitivity and high selectivity.

[0071] An atomic cluster refers to a relatively stable microscopic and sub-microscopic aggregate composed of several to thousands of atoms through physical or chemical bonding. The composite of metal M and MXene material in the form of clusters means that in the composite material, the metal components are not necessarily all single-atom dispersed, but can also be atomic clusters composed of multiple atoms.

[0072] Please refer to Figure 2 , Figure 2 which is the transmission electron microscope (TEM) image of the gas sensing material according to one or more embodiments, Figure 2 in which multiple metal atoms exist in the form of clusters, specifically manifested as the nanoclusters circled in the figure. The metal atoms can exist in multiple clusters, and the sizes of the multiple atomic clusters are different, and their sizes can be 1 - 50 nm; for example, they can be 2 nm, 5 nm, 8 nm, 10 nm, 20 nm, 30 nm, 50 nm, etc. In this way, the metal atomic clusters have a very high specific surface area and surface energy, making the surface atoms highly active. Therefore, their chemical properties are extremely unstable and they are very easy to combine with other atoms, thus easily combining with gas molecules, and ultimately being able to improve the sensitivity of the gas sensing material. At the same time, due to the atomic clusters, the loading amount of metal M in the composite material can also be increased.

[0073] By using the M / MXene composite material as the gas sensing material, in which metal M is combined with the MXene material in the form of single atoms and / or clusters, the electrochemical performance of the MXene material can be improved. At the same time, the tunability of the electronic structure of metal M and the exposure of active sites can serve as reaction centers for binding with gas molecules, accelerating the charge transfer rate between gas molecules and the M / MXene composite material, increasing the active sites of the gas-solid surface reaction, making the response sensitivity of the gas sensing material increased, the detection limit decreased, and the selectivity enhanced. When applied to a battery, it can improve the safety performance of the battery and extend the service life of the battery.

[0074] According to some embodiments of the present application, metal M in the M / MXene composite material is embedded in the structure of the MXene material in the form of single atoms. Specifically, metal M can be pinned at the defect sites of MXene in the state of single atoms.

[0075] Among them, due to the high surface free energy, single atoms tend to agglomerate. To overcome the tendency of single-atom agglomeration, single atoms can be anchored by forming strong chemical interactions between single atoms and supports. On the one hand, defect engineering can be used to create defects on the support and utilize the defects to fix metal single atoms. This is because compared with the complete carbon lattice, intrinsic defects, such as edge sites and in-plane topological defects, will lead to charge localization by forming more electronic states near the Fermi level. Therefore, intrinsic defects are also considered as an important type of anchoring sites to obtain single-atom materials. Polyatomic vacancies can capture transition metal atoms with larger radii and maintain stability. Based on this, in one embodiment of the present application, defect sites can be created on MXene and then combined with metal M so that metal M is pinned at the defect sites of MXene in the form of single atoms.

[0076] On the other hand, doped hetero-nonmetal atoms can be used to anchor metal single atoms. Hetero-nonmetal atoms can serve as additional coordination sites to anchor single metal atoms to achieve a high loading amount. The surface unsaturated sites on metal compounds can stabilize atoms by forming strong chemical bonds with atoms, and the type, quantity, uniformity, etc. of the surface unsaturated sites affect the loading amount of metal single atoms. Different characteristics of the anchoring sites directly affect the electronic structure of single metal sites, thereby affecting the gas response performance of single atoms.

[0077] Heteroatoms can realize the regulation of the electronic structure of active metal center sites and can also significantly change the long-range atomic arrangement and electronic structure of the support. Hetero-nonmetal atoms can be oxygen (O), carbon (C), nitrogen (N), sulfur (S), phosphorus (P), etc., which can act as linking atoms to form chemical bonds with single metal atoms to form stable single metal atom sites. Based on this, in one embodiment of the present application, metal atoms can be connected to the surface of the support by bonding with coordination atoms on the support. According to some embodiments of the present application, metal M in the M / MXene composite material is loaded on the surface of the MXene material in the form of a metal nitrogen-carbon compound.

[0078] Please refer to Figure 3 and Figure 4 , Figure 3 which are energy-dispersive spectroscopy (HAADF-STEM EDS) images of a high-angle annular dark-field scanning transmission electron microscope of a gas sensing material according to one or more embodiments. Figure 4 which is a synchrotron radiation X-ray absorption spectrum (XAFS) diagram of a gas sensing material according to one or more embodiments. In this embodiment, metal nickel (Ni) and MXene (Ti 3 C 2 T x) composite material as an example, using a JEOL ARM 200F instrument, an energy-dispersive spectroscopy (EDS) map was taken under the condition of 200 kV. As can be seen from the Figure 3 shown EDS map, the composite material contains nickel (Ni), nitrogen (N), carbon (C) and titanium (Ti) elements, and the nickel (Ni) element is evenly distributed. Further, XAFS spectra at the Ni K-edge were collected in fluorescence mode on the XAFCA beamline of the Singapore Synchrotron Light Source (SSLS), using Ni foil, nickel oxide (NiO), Ni nanoparticles (Ni NPs / N-C), and Ni-N-C reference (a compound formed by a known metal M in the form of a metal-nitrogen-carbon compound) as references. Among them, the reference examples of Ni foil and Ni nanoparticles (Ni NPs / N-C) are to provide references for the absorption peaks of Ni-Ni bonds to prove whether there are Ni-Ni bonds in the composite material; the reference example of nickel oxide (NiO) is to provide a reference for the absorption peak of Ni-O bonds to prove whether there are Ni-O bonds in the composite material; the reference example of Ni-N-C reference is to provide a reference for the absorption peak of Ni-N / C bonds to prove whether there are Ni-N / C bonds in the composite material. As can be seen from Figure 4 , compared with Ni foil, nickel oxide and Ni nanoparticles, at the peak positions of Ni-Ni and Ni-O bonds, the Ni / MXene composite material has no absorption peaks, indicating that there are no Ni-Ni bonds in the Ni / MXene composite material and Ni exists in the form of single atoms; while compared with Ni-N-C, the Ni / MXene composite material has obvious absorption peaks at the peak position of Ni-N bonds, indicating that Ni and N are bonded in the Ni / MXene composite material to form metal nitrides, hereinafter referred to as MN x for representation.

[0079] By bonding the metal M with nitrogen atoms, the metal M can form a strong interaction with the carrier, so the metal M can be stably fixed on the surface of the MXene material to form a stable M / MXene composite material.

[0080] According to some embodiments of the present application, each metal atom M in the metal-nitrogen-carbon compound is bonded to four nitrogen atoms respectively.

[0081] Please refer to Figures 3 to 6 , Figure 5 , which is the synchrotron radiation X-ray absorption near-edge structure (XANES) spectrum of the gas sensing material according to one or more embodiments. As can be seen from Figure 5 , the valence state of Ni is between 0 and +2. It shows that nickel compounds are formed and do not exist in the form of clusters (0 valence). In nickel compounds, nickel atoms will lose two 4s electrons to form Ni 2+Ions with an electronic structure of [Ar]3d ^ 8. Figure 6 is the synchrotron radiation X-ray absorption spectrum (XAFS) diagram of the gas sensing material according to one or more embodiments. From the Figure 6 absorption peak of the Ni-N bond in, it can be seen that the coordination number of Ni with N is 4, that is, each metal atom M is bonded to four nitrogen atoms respectively, which is hereinafter represented by MN 4 . At the same time, according to the Figure 6 chemical structure in, the XAFS spectrum of Ni-N-C / Ti 3 C 2 T x was theoretically fitted, and the actual test results coincide with the theoretical fitting results, proving that the configuration of Ni in the composite material is as shown in the Figure 6 chemical structure, and each Ni is bonded to four single atoms respectively. Different numbers of atoms and coordination structure environments can induce changes in the electronic structure of metal active sites, thus bringing differences in gas sensing responsiveness and selectivity.

[0082] In this embodiment, the metal nitride (MN 4 ) has the electronic structure characteristics of noble metals (Pd, Pt). Through the platinum-like electronic structure, the MN 4 active sites form an interfacial confinement structure with the substrate MXene (Ti 3 C 2 T x ), and then a confinement effect is formed between the substrates. At the same time, it has the sensing mechanisms of chemical sensitization and electronic sensitization, and enhances the sensing performance through the electron spill-over effect. Specifically, in the electron spill-over effect, the electrons on the metal center can be transferred to the molecules adsorbed on the surface, making the composite material have a higher active sensing performance, high sensitivity and good selectivity.

[0083] The occurrence of the electron spill-over effect is usually related to the electron density of the metal center, the adsorption mode of gas molecules, and the interaction between the metal and gas molecules. This makes the metal nitride carbon compound have a highly tunable electronic structure. Therefore, the gas sensing performance can be optimized and regulated by adjusting the electron density of the metal center and the adsorption mode of gas molecules, and the selectivity and sensitivity of the gas sensing material to the response gas can be improved.

[0084] According to some embodiments of the present application, the carbon atoms in the metal nitride carbon compound exist in the form of graphite. The nitrogen atoms bonded with metal atoms are embedded in the graphite layer and bonded to the carbon atoms of the graphite layer, and the graphite is combined on the surface of the MXene material.

[0085] Please refer to Figure 7 , Figure 7XRD image of the gas sensing material according to one or more embodiments. In this embodiment, a composite material of metallic nickel (Ni) and MXene (Ti 3 C 2 T x ) is taken as an example for X-ray diffraction test. N-C, Ni-N-C, and Ni NPs / N-C are used as references; among them, N-C is an N-C material without Ni doping, and the synthesis process is direct calcination of ZIF-8 material; Ni-N-C is a nickel-nitrogen atomic nitrogen-carbon compound, and the synthesis process is calcination of nickel nitrate + ZIF-8; Ni NPs / N-C is nickel nanoparticles / nitrogen-carbon compound, and the synthesis process is calcination of nickel nitrate + ZIF-8, and the difference from Ni-N-C is the proportion of nickel nitrate.

[0086] From Figure 7 it can be seen that the spectrum of the Ni / MXene composite material includes a characteristic diffraction peak of Ti 3 C 2 T x at about 2θ = 6.2°, and a characteristic diffraction peak of graphite appears at about 2θ = 26.4°.

[0087] By using the graphite layer as the carbon material carrier, it can provide a connection framework for the MN 4 groups, enabling the MN 4 groups to be loaded, and then combined with MXene through graphite. Further, the hierarchical pore structure of the graphite layer can also provide more binding sites for gas molecules, increasing the sites for gas binding reactions. In addition, graphite can improve the volume density, conductivity, corrosion resistance, and machining performance of the carbon material carrier, thereby improving the conductivity of the gas sensing material.

[0088] According to some embodiments of the present application, the metal nitrogen-carbon compound is doped with element X, and X includes one or more of sulfur (S), phosphorus (P), and boron (B).

[0089] The doped element X is a non-metal element, and this non-metal element can coordinate and bond with metal M and carbon (C) atoms, and can capture atomically dispersed metal sites, making it not easy to lose or release. The electronegativity of elements such as sulfur, phosphorus, and boron has a large difference from the electronegativity between carbon and nitrogen, which means that their addition can introduce additional charge distribution or polar properties, change the electronic structure of the material, and achieve the modification of single-atom performance. In addition, due to the difference in electronegativity, the conductivity and gas adsorption characteristics of the material can be adjusted, and then the response performance of gas sensing can be adjusted.

[0090] Furthermore, in the metal nitrogen carbide, each metal atom M is bonded to four nitrogen atoms respectively, and the doped X element replaces one or more of the four nitrogen atoms bonded to the metal atom M.

[0091] According to the ligand field theory, the bonding of metal complexes is similar to the interaction between positive and negative ions in an ionic crystal: First, the interaction between the metal and the ligand is an electrostatic interaction, and the ligand is regarded as a point charge; Second, the role of the ligand is to establish a negative charge potential field. Under the perturbation of the negative charge potential field, the d orbitals of the metal undergo energy level splitting; Third, the electrons of the metal fill the split d orbitals from low to high, causing the total energy to decrease and generating an additional bonding effect. Therefore, the ligand has an impact on the d orbitals of the central metal atom M surrounded by it. The strength of the interaction between the metal atom and the ligand determines the rise and fall of different d orbitals in terms of energy level. Therefore, the electronic structure and gas sensing performance of the metal nitrogen carbide material can be regulated by adjusting the ligands around the metal atom center.

[0092] The doped element replaces some or all of the nitrogen atoms in MN as the coordinating atom of the metal atom center. By constructing different ligand types, the structure of the central metal atom can be optimized, thereby improving the sensitivity, selectivity, and stability of the sensor. x

[0093] According to some embodiments of the present application, the metal M includes one or more of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), iridium (Ir), ruthenium (Ru); optionally, the metal M includes one or more of Fe, Co, Ni.

[0094] The elemental type of the metal M belongs to transition metal elements. Transition metal elements have a special electronic structure, with unfilled valence layer d orbitals and a relatively high charge / radius ratio, and are prone to forming stable coordination compounds with ligands. In addition, different metal species have different electronic structures, resulting in differences in the binding to gas molecules.

[0095] Among them, the metal M is dispersed in the composite material in the form of single atoms or clusters. The metal single atoms and their local coordination environments constitute metal single atom sites. The active sites of each metal single atom are not necessarily completely identical. The non-uniformity of the carrier surface, etc., will lead to the non-uniformity of the coordination environment around the single atom and the difference in intrinsic activity. The atomically dispersed metal and its adjacent coordination environment play a crucial role in determining activity, selectivity, and stability. The response sensitivity and selectivity of gas sensing can be regulated by selecting different metal elements.

[0096] In one embodiment, a composite material can contain multiple different types of metal atoms simultaneously, such as Fe and Ni. Different metals can be dispersed on the carrier in the form of single atoms or clusters respectively; or single-atom alloys can be formed, where the non-metal carrier in the single-atom alloy is replaced by a metal support, and the active metal single atoms interact with the metal support in the form of metal-metal bonds.

[0097] According to some embodiments of the present application, based on the total number of atoms in the M / MXene composite material, the atomic content (at%) of the M element is less than or equal to 15%; optionally, the atomic content (at%) of the M element is less than or equal to 10%; optionally, the atomic content (at%) of the M element is less than or equal to 5%. For example, it can be 0.1%-2%, 2%-5%, 5%-8%, 8%-10%, 10%-12%, 12%-15%, etc.

[0098] The atomic content of an element refers to the percentage of the number of atoms of that element in the total number of atoms of the material. The atomic content of the M element refers to the percentage of the number of atoms of the M element in the total number of atoms of the M / MXene composite material. M atoms serve as active centers for binding gas molecules. Increasing the content of M atoms can increase the number of active adsorption sites, thereby increasing the detection sensitivity of the sensor to the target gas. As the content of M atoms increases, it is easier to agglomerate into clusters, which may instead reduce the sensing performance.

[0099] By selecting the atomic content of the M element, the sensitivity and selectivity of the gas sensing material can be adjusted. According to different application scenarios, prioritize sensitivity or selectivity, and make a trade-off between the two to meet the requirements of specific applications.

[0100] In some embodiments of the present application, the response gases of the gas sensing material include CO, NO 2 , NO, H 2 , CH 4 , H 2 , H₂S, ethylene, ethane, volatile organic compounds, any one of volatile electrolytes; optionally, the volatile organic compounds include any one of methanol, formaldehyde, toluene, styrene, phenol, benzene; optionally, the volatile electrolytes include any one of polyether electrolytes, polyester electrolytes.

[0101] During the normal charging and discharging processes of batteries and when battery thermal runaway occurs, different types of batteries produce different gases. For example, lead-acid batteries produce hydrogen, lithium-ion batteries produce carbon monoxide, carbon dioxide, and hydrocarbon gases including methane, ethane, and ethylene, sodium-ion batteries also produce hydrogen, and lithium-sulfur batteries may produce hydrogen and hydrogen sulfide gases. In addition, volatile electrolytes are a commonly used electrolyte in batteries or energy storage devices. They have high volatility and are usually organic compounds. In the case of battery failures, volatile electrolytes may volatilize and thermally decompose, producing gases including carbon monoxide, carbon dioxide, and nitric oxide. The gas sensor provided by this application can be applied to the above different batteries to detect different gases.

[0102] In some embodiments of this application, the gas sensing material has a sensing response to gases in the range of -55°C to 65°C. This is beneficial for the gas sensing material to adapt to different working environments and reduce the problem of gas sensing material failure caused by temperature. In particular, the gas sensing material can still have a sensing response to gases at a relatively low temperature, indicating that the gas sensing material has high activity and can adapt to the working environment under extremely cold conditions. This is of great significance for the safety performance of some batteries applied to special environments.

[0103] The working temperature of conventional lithium-ion batteries is between -20°C and 60°C. However, generally, the performance of lithium batteries will decline after the temperature is lower than 0°C, and the discharge capacity will decrease accordingly. Therefore, the common working temperature range for the complete performance of lithium-ion batteries is 0°C to 40°C; lead-acid batteries usually work in a relatively wide temperature range, roughly between -20°C and 50°C; lithium polymer batteries are similar to lithium-ion batteries and usually work between -20°C and 60°C. The typical working temperature range of sodium-ion batteries is approximately between -10°C and 60°C. The typical working temperature range of lithium-sulfur batteries is usually between -20°C and 60°C. Similar to lithium-ion batteries, the performance of lithium-sulfur batteries may be limited under extreme temperature conditions.

[0104] Most of the existing other gas sensing materials only have a gas response effect at temperatures of 80 - 90°C or even higher and cannot be applied to the battery system. However, the gas sensing material provided by this application has a good response effect at low temperatures and has a gas response temperature range that can match the working temperatures of most batteries.

[0105] In the above embodiments, by selecting a composite of metal single atoms or clusters and a carrier as the gas sensing material, gas detection can be achieved in an anaerobic or low-oxygen environment, with high response sensitivity, low detection limit, strong selectivity, and rapid response and recovery. The composite of metal single atoms or clusters and a carrier can be prepared by physical methods such as atomic layer deposition, physical / chemical vapor deposition; or by chemical methods such as co-deposition, pyrolysis method.

[0106] In some embodiments of the present application, there is also provided a method for preparing a gas sensing material, including: providing a composite of MXene and a metal-organic complex, the metal-organic complex being a complex of metal M and an organic ligand; calcining the composite to obtain an M / MXene composite material, in which metal M in the M / MXene composite material is combined with the MXene material in the form of single atoms; and / or metal M in the M / MXene composite material is combined with the MXene material in the form of clusters.

[0107] The metal-organic complex is a precursor of metal single atoms and metal clusters. The precursor containing metal nodes can be used to prepare single-atom composites through pyrolysis. During the calcination process, metal single atoms and / or metal clusters are formed by pyrolysis. During the high-temperature pyrolysis process, there is a strong interaction between the single atoms and the pyrolysis products, forming a composite.

[0108] The metal-organic complex is usually a complex formed by metal ions and organic ligands, such as organic complexes of metal acetates, metal nitrates, metal chlorides, or metal-organic framework materials. During the calcination process, the metal ions will be decomposed or reduced to become metal atoms or metal clusters.

[0109] Among them, the organic ligand is a molecule or ion in an organic compound, usually containing elements such as carbon, hydrogen, oxygen, nitrogen, etc. Common organic ligands such as ethylenediamine, dimethylimidazole, etc. They can form coordination bonds with metal atoms, thus constituting a metal-organic complex. Further, when preparing a metal single-atom composite, the metal-organic complex can also provide hetero non-metal atoms (such as carbon, nitrogen, etc.) to anchor metal single atoms and metal clusters, so as to form stable metal atom sites.

[0110] In some embodiments of the present application, the metal M in the M / MXene composite material is loaded on the surface of the MXene material in the form of a metal nitride carbide, and this type of composite is hereinafter referred to as the M-N-C / MXene composite material. Specifically, each metal atom M in the metal nitride carbide may be bonded to four nitrogen atoms respectively. The carbon atoms in the metal nitride carbide exist in the form of graphite. The nitrogen atoms bonded with the metal atoms are embedded in the graphite layer and bonded to the carbon atoms in the graphite layer, and the graphite is combined on the surface of the MXene material. The M-N-C / MXene composite material can be prepared by calcining the composite of MXene and a metal-organic complex.

[0111] In some embodiments of the present application, first prepare the composite of MXene and a metal-organic complex. Specifically, the metal-organic complex solution can be mixed with the MXene solution and stirred to react to obtain the composite of MXene and the metal-organic complex.

[0112] In some embodiments of the present application, before mixing the metal-organic complex solution with the MXene solution, it includes: combining the metal-organic complex with a surfactant; and / or combining the MXene material with a surfactant.

[0113] A surfactant refers to a substance that can significantly reduce the surface tension of the target solution. A surfactant has a fixed hydrophilic-lipophilic group and can be oriented on the surface of the solution. The molecular structure of a surfactant has amphoteric properties: one end is a hydrophilic group, and the other end is a hydrophobic group. The hydrophilic group is often a polar group, such as carboxylic acid, sulfonic acid, sulfuric acid, amino or amine group and its salts, and hydroxyl group, amide group, ether bond, etc. can also be used as polar hydrophilic groups; while the hydrophobic group is often a non-polar hydrocarbon chain, such as a hydrocarbon chain with more than 8 carbon atoms. Surfactants are divided into ionic surfactants (including cationic surfactants and anionic surfactants), non-ionic surfactants, amphoteric surfactants, compound surfactants, other surfactants, etc.

[0114] By mixing the surfactant with at least one of them before mixing the metal-organic complex solution with the MXene solution, the surfactant is first connected to the metal-organic complex or MXene. The presence of the surfactant can connect the metal-organic complex and MXene through the hydrophilic-lipophilic groups during the mixing reaction between the metal-organic complex and MXene, acting as a bridge for their combination, which is beneficial to improving the interfacial affinity between the metal-organic complex and MXene and promoting a more effective reaction. In addition, the surfactant has the function of a dispersant, which is beneficial to the uniform dispersion of the metal-organic complex and MXene in the solution, thus being beneficial to the uniformity and stability of the reaction.

[0115] In one embodiment, the surfactant includes cetyltrimethylammonium bromide. Cetyltrimethylammonium bromide (CTAB) belongs to cationic surfactants and has a hydrophilic-lipophilic balance value (HLB) of 15.8. In the CTAB molecular structure, there is a hydrophobic alkyl chain (cetyl group), which has lipophilic properties. At the same time, the ammonium bromide ion part in the CTAB molecule has hydrophilic properties. This molecular structure enables CTAB to have both hydrophilic and lipophilic amphoteric properties. The hydrophilic group of CTAB is connected to MXene, and the lipophilic group is connected to the metal-organic complex, realizing the composite of the metal-organic complex and MXene.

[0116] In addition, the CTAB molecule carries a positive charge because the ammonium ion (NH 4+ ) in the ammonium bromide ion carries a positive charge, and this positive charge can interact with a negatively charged surface or particles. By using CTAB as the surfactant, the positive ion part of CTAB can attract the negatively charged functional groups (such as -OH, -F) on MXene and the negative charges on the surface of the metal-organic complex, which is beneficial to improving the stability of the connection.

[0117] Furthermore, in some embodiments of the present application, it is preferred to combine the metal-organic complex with the surfactant, specifically including: providing a metal-organic complex precursor and cetyltrimethylammonium bromide; mixing and reacting the metal-organic complex precursor and cetyltrimethylammonium bromide to obtain a metal-organic complex combined with cetyltrimethylammonium bromide.

[0118] As mentioned above, the positive ion part of CTAB can attract the negative charges on the surface of the metal-organic framework material to form an adsorption layer, and this adsorption is usually achieved through electrostatic interaction. The hydrophobic alkyl chain of CTAB can interact with the hydrophobic region of the metal-organic complex, further stabilizing the adsorption layer. This binding method can help disperse and stabilize the metal-organic complex and regulate its properties.

[0119] Next, the composite of the metal-organic complex solution and the MXene solution can be carried out by mixing the metal-organic complex combined with cetyltrimethylammonium bromide and the MXene solution, stirring and reacting to obtain a composite.

[0120] In the composite of the metal-organic complex and the MXene solution, the surfactant plays a key role. As mentioned above, the surfactant serves as a bridge for the combination between the metal-organic complex and the MXene solution, improving the interfacial affinity between the metal-organic complex and MXene and promoting a more effective reaction.

[0121] According to some embodiments of the present application, mixing the metal-organic complex solution with the MXene solution includes: dropping the MXene solution into the metal-organic complex solution in a stirred state; optionally, the dropping rate of the MXene solution is 1-20 seconds per drop. The stirred state is conducive to the full contact between the MXene solution and the metal-organic complex solution, accelerating the reaction rate; by controlling the dropping rate, the local solution concentration of the reaction can be adjusted, and dropping one by one can form a relatively uniform reaction concentration field, which is conducive to the formation of well-dispersed and uniform-sized crystals.

[0122] Specifically, while stirring, the MXene solution is dropped into the metal-organic complex solution, the dropping rate of the MXene solution is 2 seconds per drop. After the dropping is completed, stirring is continued for 24 hours. After the reaction is completed, the product is washed with methanol and vacuum dried at 60 °C to obtain a composite of MXene and metal-organic complex.

[0123] Through the above reaction, a composite of MXene and metal-organic complex is prepared, which is the precursor of the M / MXene composite material and the prerequisite for finally obtaining the M / MXene composite material.

[0124] Furthermore, the composite of MXene and metal-organic complex prepared is calcined. According to some embodiments of the present application, the composite of MXene and metal-organic complex is calcined to obtain the M / MXene composite material.

[0125] The calcination step is a process of converting the metal-organic complex precursor into a metal single atom or metal cluster complex. A metal-nitrogen-carbon (M-N-C) structure can also be formed during calcination. At high temperatures, the metal-organic complex precursor will undergo decomposition or reduction reactions to generate metal single atoms or metal clusters; at the same time, at high temperatures, the volatile elements in the metal-organic complex precursor volatilize, forming a porous carbon with a graphite phase structure. For example, when the metal-organic complex precursor is zeolitic imidazolate framework-8 (ZIF-8), at a pyrolysis carbonization temperature of 900 °C, the volatile zinc at high temperatures is removed from the structure of ZIF-8, and finally a non-metal nitrogen-doped graphitized porous carbon material is obtained. This material retains the regular rhombic dodecahedron morphology of ZIF-8, has a high nitrogen content, a high specific surface area and a hierarchical pore structure.

[0126] Please refer to Figure 8 , Figure 8 for the reaction schematic diagram of the preparation of the gas sensing material according to one or more embodiments. Using metal nickel (Ni) and MXene (Ti 3 C 2 T x) composite material as an example, in this case the metal-organic complex is nickel-based zeolitic imidazolate framework-8 (Ni-ZIF-8). The metal-organic complex Ni-ZIF-8 first connects with the surfactant CTAB to form Ni-ZIF-8-CTAB. ZIF-8 is a metal-organic framework material with a network porous crystal structure. CTAB wraps ZIF-8 to form active sites on the surface of ZIF-8; next, Ni-ZIF-8-CTAB connects with Ti 3 C 2 T x through the active sites formed by CTAB to complete the self-assembly of the metal-organic complex Ni-ZIF-8 and MXene Ti 3 C 2 T x . Then it is calcined and pyrolyzed to form Ni-N-C / Ti 3 C 2 T x composite material. In the Ni-N-C / Ti 3 C 2 T x composite material, Ni forms bonds with four Ns respectively to form a NiN 4 structure, the structure shown in the black central area of the upper structure in the figure, and then the NiN 4 structure bonds with the graphite structure formed by carbonization, the upper structure in the figure, and finally the graphite structure composites with MXene (Ti 3 C 2 T x ).

[0127] According to some embodiments of the present application, the calcination temperature is 700 - 1000 °C, preferably 850 - 950 °C; and / or the calcination time is 1 - 4 h.

[0128] Within this temperature and time range, the organic components in the metal-organic complex can undergo pyrolytic carbonization to form porous carbon with a graphite phase structure. At the same time, some metal ions in the metal-organic complex framework volatilize at high temperature to form defects and active sites.

[0129] Please continue to refer to Figure 8 , taking the metal-organic complex Ni-ZIF-8 as an example. When the calcination temperature is lower than 500 °C, the sample retains the structure and morphology of ZIF-8; when the temperature reaches 600 °C, ZIF-8 begins to decompose and carbonize; as the temperature further increases, Zn in ZIF-8 2+ volatilizes above 750 °C, and ZIF-8 carbonizes into porous carbon with a graphite phase structure. Under anaerobic conditions, MXene has very little mass loss within this temperature range, and its structure and composition hardly change.

[0130] Through the pyrolytic carbonization and metal ion volatilization occurring during the calcination process, metal M is loaded on the surface of the MXene material in the form of a metal-nitrogen-carbon compound, where carbon atoms exist in the form of graphite, and nitrogen atoms bonded with metal atoms are embedded in the graphite layers and bonded to the carbon atoms of the graphite layers.

[0131] According to some embodiments of the present application, calcining the composite includes: calcining the composite in an atmosphere of a protective gas. Optionally, the protective gas includes one or more of argon, hydrogen, and nitrogen.

[0132] The protective gas is a gas with stable properties, and its main function is to prevent oxidation reactions during the calcination process. Among them, argon is an inert gas with inactive chemical properties. Using it as a protective gas can isolate air and prevent oxidation. Nitrogen has stable properties and can also isolate air and prevent oxidation. In addition to the above functions, hydrogen also has a certain reducing effect to further prevent oxidation. The above protective gas can be a single gas or a mixed gas of two or more gases.

[0133] By introducing a protective gas in the calcination step, first, it can reduce the oxidation reaction during the preparation of the gas sensing material, which is beneficial to reducing the oxidation of MXene, protecting the activity of the active sites on the material surface, maintaining the normal progress of the reaction, and improving the product quality.

[0134] The gas sensing material prepared by the above method has a MXene and M-N-C interfacial confinement structure, thereby forming a confinement effect between the substrates, and at the same time has a sensing mechanism of chemical sensitization and electronic sensitization, and enhances the sensing performance through the electron spillover effect.

[0135] According to some embodiments of the present application, the M / MXene composite material can also be doped. Specifically, during the preparation process of the M / MXene composite material, doping elements can be introduced at different process stages.

[0136] According to some embodiments of the present application, in the calcination step, the composite can be calcined in an atmosphere of a doping gas to introduce doping elements through the gas atmosphere. Optionally, the doping gas includes one or more of ammonia and hydrogen sulfide.

[0137] Different from the protective gas, the doping gas can participate in the reaction while protecting the reaction. For example, ammonia can introduce nitrogen atoms into the metal atom ligands of the M / MXene composite material, and hydrogen sulfide can introduce sulfur atoms, that is, a coordination bond is formed between the metal atom M and the nitrogen atom or sulfur atom, replacing one or more of the four single atoms bonded to the metal atom M, so as to optimize the sensing performance of the gas sensing material and enhance the adaptability of the gas sensing material to different application requirements.

[0138] According to some embodiments of the present application, the doping element can also be introduced at the metal-organic complex stage. Specifically, the metal-organic complex is doped and modified before mixing the metal-organic complex solution with the MXene solution.

[0139] The doped and modified ligand can be a ligand containing chalcogen elements such as O and S, such as -O, -OH, -S. Due to the differences in the chemical properties of non-metallic elements such as N, O, and S themselves, when they coordinate and bond with the metal atom center to form a special configuration, they can adjust the electrical properties such as the spin state and d-band center of the metal center, and then regulate the binding energy between the active center and gas molecules, ultimately achieving the regulation of the intrinsic activity of the gas sensing material. It can also be halogen elements such as F, Cl, Br, and I. Due to the differences in electronegativity between ligand elements, different ligands can regulate the electronic structure of the metal atom center to different degrees, and ultimately can achieve the regulation of the responsiveness, selectivity, etc. of the gas sensing material.

[0140] In some embodiments of the present application, before mixing the metal-organic complex solution with the MXene solution, it includes: providing a metal-organic complex precursor and a doping precursor; mixing and reacting the metal-organic complex precursor and the doping precursor to obtain a doped and modified metal-organic complex.

[0141] The doping precursor refers to a compound used to introduce a doping element. It can be a single compound or a product obtained by specific treatment or modification of the metal-organic complex precursor. The choice of the doping precursor depends on the desired doping element and the specific application requirements of the material.

[0142] The doping precursors mainly include the following types. One is metal salts, such as metal nitrates, metal chlorides, metal acetates, etc. By reacting the metal salt with the metal-organic complex precursor, the doping process can be achieved. The second is organic compounds, which contain the target doping element and can be functional ligands, such as organic acids, ketones, alcohols, etc. containing specific functional groups. The third is a gas source, such as the doping gas atmosphere in the calcination step mentioned above. Introducing the doping gas into the reaction system of the metal-organic complex precursor can achieve the introduction of the doping element. In one embodiment of the present application, the doping precursor is thiourea, an organic sulfur-containing compound with the chemical formula CH 4 N 2 S, which can provide sulfur element as the doping element. The specific doping steps are detailed in the specific examples later.

[0143] By mixing a doping precursor and a metal-organic complex precursor to carry out a reaction, a doped and modified metal-organic complex is obtained. By preferably selecting a suitable doping precursor, the doping purpose can be effectively achieved, and doping of multiple elements can be realized. Furthermore, it is beneficial to modify the gas sensing material purposefully and broaden the application range of the gas sensing material.

[0144] In the above embodiments, through doping modification, it is possible to adaptively design the gas sensing material starting from specific gas types and response effects for specific application scenarios, which is beneficial to modify the gas sensing material purposefully and broaden the application range of the gas sensing material.

[0145] In some embodiments of the present application, a metal single-atom composite material can also be prepared by using the defect vacancy anchoring method. By utilizing the lattice defects of the MXene support material, metal atoms M are anchored. The metal atoms M coordinate or form bonds with surrounding support atoms (usually C atoms) and become part of the lattice structure. Due to the existence of chemical bonds and the influence of the nanoconfinement effect, the doped metal atoms M have high stability. It can be that during the process of etching the MAX-phase precursor to prepare MXene, some adjacent metal atoms in the MAX phase will fall off, resulting in the generation of metal vacancy defects. These defects have high reduction activity and can spontaneously reduce and adsorb metal ions to fix single metal atoms without adding any reducing agent, so that isolated metal atoms stably exist on the MXene support. In the metal single-atom composite material prepared by this method, the metal M is embedded in the structure of the MXene material in the form of single atoms.

[0146] Specifically, in an embodiment of the present application, lithium fluoride (LiF) and hydrochloric acid (HCl) solution are used to etch aluminum titanium carbide (Ti 3 AlC 2 ) to prepare Ti 3 C 2 T x nanosheets. During this process, the Ti-Al bond is broken, causing the etching of adjacent Ti atoms and resulting in the formation of Ti single vacancies or vacancy clusters. These vacancies can adsorb Ni 2+ and reduce it in-situ to prepare a single-atom Ni-modified Ni-Ti 3 C 2 T x MXene composite material. The specific preparation method is described in detail in the specific embodiments below.

[0147] In some embodiments of the present application, a gas sensor is also provided. The gas sensor includes the gas sensing material of any one of the above; or includes the gas sensing material prepared by using any one of the above methods.

[0148] Specifically, an M / MXene composite material is used as a gas sensing material. Based on the change in surface conductivity during the adsorption and desorption of gas on the material surface, the material can respond to the sensed gas and can achieve gas response under anaerobic conditions. A gas sensor that can quickly respond to gas and has high detection sensitivity under anaerobic conditions is prepared. The gas sensor can respond to one or more gases including CO, NO 2 、NO、H 2 、CH 4 、H 2 S, ethylene, ethane, volatile organic compounds, and volatile electrolytes.

[0149] In order to make the technical problems, technical solutions, and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail in combination with embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on the present application and its application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0150] I. Preparation of Gas Sensing Material

[0151] Example 1

[0152] 1. Dissolve 0.96 g of zinc nitrate hexahydrate in 67 mL of methanol, and then add 50 mg of nickel nitrate hexahydrate and stir evenly to obtain solution A;

[0153] 2. Dissolve 0.4 g of cetyltrimethylammonium bromide (CTAB) and 2.19 g of dimethylimidazole in 67 mL of methanol solution, and stir until completely dissolved as solution B;

[0154] 3. While stirring, slowly drip solution B into solution A at a rate of 2 seconds per drop. After the dripping is completed, continue stirring for 2 h. Take 35 mL of the mixed solution as solution C;

[0155] 4. Dissolve 0.2 g of MXene in 5 mL of methanol solution and ultrasonically dissolve it completely as solution D;

[0156] 5. While stirring, slowly drip solution D into solution C at a rate of 2 seconds per drop. After the dripping is completed, continue stirring for 24 h, wash with methanol and dry in vacuum at 60 °C. Place the product in a tube furnace and calcine it at 900 °C for 2 h in a nitrogen atmosphere to obtain the (Ni-N-C / MXene)-1 composite material, in which Ni is combined with the MXene material in the form of single atoms.

[0157] Examples 2 - 3

[0158] On the basis of Example 1, the preparation of Solution A was changed. The difference is that nickel nitrate hexahydrate was replaced with iron nitrate hexahydrate and cobalt nitrate hexahydrate respectively, and the (Fe-N-C / MXene)-2 composite material and the (Co-N-C / MXene)-3 composite material were prepared. Fe and Co were respectively combined with the MXene material in the form of single atoms. The specific reaction conditions are shown in Table 1, and Table 1 lists the types of metal M and the forms of metal M in each example.

[0159] Example 4

[0160] On the basis of Example 1, the preparation of Solution A was changed. The difference is that the mass of nickel nitrate hexahydrate was replaced from 50 mg to 500 mg, and the (Ni-N-C / MXene)-4 composite material was prepared. Ni was combined with the MXene material in the form of clusters. The specific reaction conditions are shown in Table 1.

[0161] Example 5

[0162] 1. Add 1 g of lithium fluoride (LiF) to 10 mL of hydrochloric acid (HCl) solution, stir for 1 h, and then add 1 g of titanium aluminum carbide (Ti 3 AlC 2 ) powder, heat in a water bath at 35 °C, and react for 24 h; repeatedly wash the solution obtained after the water bath with deionized water by centrifugation until the pH ≥ 5.5, the centrifugation rate is 9000 rpm, and the centrifugation time for each time is 5 min; add 40 mL of deionized water to the centrifuged product, and ultrasonicate for 30 min to obtain a suspension, and obtain a Ti 3 C 2 T x MXene solution, and take 8 mL of the suspension as Solution A;

[0163] 2. Weigh 0.002 g of ferric chloride hexahydrate and add it to 50 mL of deionized water, and ultrasonicate for 30 min to obtain Solution B;

[0164] 3. Slowly add Solution B to Solution A, the dropping rate of Solution B is 2 seconds / drop, stir for 8 h, then add 50 mL of acetone, let it stand overnight, wash with acetone and vacuum dry at 60 °C to obtain the (Ni / MXene)-5 composite material, and Ni is combined with the MXene material in the form of single atoms.

[0165] Example 6

[0166] On the basis of Example 1, the preparation of Solution A was changed. The difference is that 50 mg of nickel nitrate hexahydrate was replaced with 25 mg of nickel nitrate hexahydrate and 25 mg of iron nitrate hexahydrate, and the (Ni-Fe-N-C / MXene)-6 composite material was prepared. Ni and Fe were combined with the MXene material in the form of single atoms. The specific reaction conditions are shown in Table 1.

[0167] Example 7

[0168] On the basis of Example 1, the preparation of Solution A was changed. The difference was that 0.5 g of thiourea was added while adding nickel nitrate hexahydrate, and the (Ni-N-S-C / MXene)-7 composite material was prepared. Ni was combined with the MXene material in the form of single atoms. The specific reaction conditions are shown in Table 1.

[0169] II. Preparation of Gas Sensor

[0170] The gas sensing material was dispersed in ethanol at a concentration of 10 mg / L and ultrasonicated for 10 min at 40 KHz to make the composite material uniformly dispersed in ethanol. The gold electrodes were prepared by micromachining technology, and the distance between the positive and negative electrodes was controlled to be 800 μm, and the distance between adjacent electrodes was 300 μm. Take 5 μL of the above dispersion and drop it on the interdigital electrodes, and dry it in vacuum at 60 °C for 1 h to obtain the gas sensor.

[0171] III. Gas Sensing Performance Test

[0172] Please refer to Figure 9 , Figure 9 , which is a schematic diagram of the gas sensing performance test according to one or more embodiments. The gas sensor was placed in the test chamber. At room temperature, the target gas was introduced by the static gas distribution method, and a constant working voltage of 500 mV was applied between the sensor electrodes. The resistance change of the sensor in the inert gas and target gas environments was detected by an Agilent 4156C semiconductor parameter analyzer. Among them, before introducing the target gas, the chamber was purified with dry compressed nitrogen (MFC3) to stabilize the baseline signal, and compressed nitrogen (MFC2) was used as the carrier gas to dilute the target gas, and the target gas was controlled by a mass flow controller (MFC1). The difference between the resistance of the sensor in dry nitrogen and the target gas and the resistance ratio in dry nitrogen (|R a -R g | / R a ×100%) is the response value of the device to the target gas, and the response and recovery times are defined by reaching 90% saturation of the response and recovery curves.

[0173] Table 1 Reaction Parameters and Performance Parameters of Each Example

[0174]

[0175] Note: In Example 5, metal M was embedded in MXene in the form of single atoms, and in the examples other than Example 5, metal M was loaded on the surface of the MXene material in the form of metal nitride carbon compounds; in the column of response values, the gas concentration tested in Examples 1-7 was 20 ppm; the same applies to the column of response time / recovery time.

[0176] Please refer to Figures 11 to 13 , Figure 11 which is a schematic diagram of the gas response of the gas sensing material Ni / MXene according to one or more embodiments, Figure 12 which is a schematic diagram of the gas response of the gas sensing material Ni / MXene according to one or more embodiments, Figure 13 which is a schematic diagram of the gas response of the gas sensing material Ni / MXene according to one or more embodiments. Figure 11 The response of (Ni-N-C / MXene)-1 to CO gas at different concentrations was tested, Figure 12 and the cyclic response performance of (Ni-N-C / MXene)-1 to 1, 5, and 10 ppm CO gases was tested, Figure 13 and the response of (Ni-N-C / MXene)-1 to different gases at a concentration of 5 ppm was tested. In Figure 11 and Figure 12 , the abscissa is the acquisition time and the ordinate is the device sensitivity.

[0177] It can be seen from Figure 11 that the response value of the (Ni-N-C / MXene)-1 composite sensor to 50 ppm carbon monoxide reached 50.2%. The lowest detectable carbon monoxide concentration reached 1 ppm, and the corresponding response value was 10.4%. As the carbon monoxide concentration increased, the response value of the sensor to the gas also increased. When the carbon monoxide gas concentration was 5 ppm, the response time was 40 s and the recovery time was 120 s, and the response and recovery speeds were relatively fast. Therefore, the (Ni-N-C / MXene)-1 gas sensing material provided in this application has high sensitivity for gas detection, low detection limit, and fast response and recovery speeds.

[0178] It can be seen from Figure 12 that after five response-recovery cycles at three different gas concentrations, the response value and response time of the (Ni-N-C / MXene)-1 composite sensor remained basically unchanged, indicating that the (Ni-N-C / MXene)-1 gas sensing material provided in this application has good cyclic stability in gas response.

[0179] It can be seen from Figure 13 that the (Ni-N-C / MXene)-1 composite material responded to 5 ppm carbon monoxide, nitric oxide, nitrogen dioxide, methane, hydrogen, and ammonia, but except for carbon monoxide, the response values to other gases were very small. This indicates that the (Ni-N-C / MXene)-1 gas sensing material provided in this application shows good selectivity to carbon monoxide.

[0180] Please refer to Figures 14 to 16 ,Figure 14 Schematic diagram of gas response of gas sensing material Fe / MXene according to one or more embodiments Figure 15 Schematic diagram of gas response of gas sensing material Co / MXene according to one or more embodiments Figure 16 Schematic diagram of gas response of gas sensing material Ni / MXene according to one or more embodiments. The abscissa is the acquisition time and the ordinate is the device sensitivity

[0181] In Figure 14 , the response of the (Fe-N-C / MXene)-2 composite material to different concentrations of NH 3 gas was tested. The response value of the (Fe-N-C / MXene)-2 composite material sensor to 20 ppm ammonia reached 30.9%. The lowest detectable ammonia concentration reached 1 ppm, and the corresponding response value was 25.6%. As the ammonia concentration increased, the response value of the sensor to the gas also increased. When the ammonia gas concentration was 20 ppm, the response time was 80 s and the recovery time was 100 s. Therefore, the (Fe-N-C / MXene)-2 gas sensing material provided in this application has high sensitivity for gas detection, low detection limit, and fast response and recovery speed

[0182] In Figure 15 , the response of the (Co-N-C / MXene)-3 composite material to 20 ppm NO 2 gas was tested. The response value of the (Co-N-C / MXene)-3 composite material sensor to 20 ppm nitrogen dioxide was 6.4%, the response time was 60 s, and the recovery time was 80 s. At the same time, the response value and response time remained basically unchanged within two cycles. Therefore, the (Co-N-C / MXene)-3 gas sensing material provided in this application can be applied to nitrogen dioxide gas detection

[0183] In Figure 16 , the response of the (Ni-N-C / MXene)-4 composite material to 20 ppm CO gas was tested. The response value of the (Ni-N-C / MXene)-4 composite material sensor to 20 ppm carbon monoxide was 5.5%, the response time was 40 s, and the recovery time was 90 s. At the same time, the response value and response time remained basically unchanged within five cycles. Therefore, the (Ni-N-C / MXene)-4 composite material provided in this application can be applied to carbon monoxide gas detection and has good gas response cycle stability

[0184] Please refer to Table 1. In Examples 1-3, (Ni-N-C / MXene)-1 composite material, (Fe-N-C / MXene)-2 composite material, and (Co-N-C / MXene)-3 composite material were prepared. The types of metal M in these three composite materials are different, so the types of gases to which the three composite materials respond are also different, which are CO, NH 3 and NO 2 . It shows that there are differences in the binding of different metal types to gas molecules. Therefore, the selectivity of gas sensing can be regulated by selecting different metal elements.

[0185] In addition, compared with (Fe-N-C / MXene)-2 composite material and (Co-N-C / MXene)-3 composite material, (Ni-N-C / MXene)-1 composite material has a higher response value and a shorter response time under the same concentration of the gas to be detected, indicating that the gas sensing material prepared with nickel element has a higher response sensitivity among the three. Therefore, the response sensitivity of gas sensing can be regulated by selecting different metal elements.

[0186] In Example 1 and Example 4, (Ni-N-C / MXene)-1 composite material and (Ni-N-C / MXene)-4 composite material were prepared. Metal Ni was combined with MXene material in the form of single atoms and clusters respectively. It can be seen that the response value of (Ni-N-C / MXene)-1 to 20 ppm CO is 43.1%, while the response value of (Ni-N-C / MXene)-4 to 20 ppm CO is only 5.5%. It shows that even though (Ni-N-C / MXene)-4 has more Ni atomic active sites, the Ni atoms in the cluster form still reduce the sensing performance.

[0187] In Example 1 and Example 5, (Ni-N-C / MXene)-1 and (Ni / MXene)-5 composite materials were prepared. Metal Ni single atoms were embedded in MXene in the form of single atoms or loaded on the surface of MXene material in the form of metal carbonitride. Please refer to Figure 10 , Figure 10 for the gas response schematic diagram of the gas sensing material Ni / MXene according to one or more embodiments. The abscissa is the acquisition time, and the ordinate is the device sensitivity. It can be seen that the response value of (Ni-N-C / MXene)-1 to 20 ppm CO is 43.1%, while the response value of (Ni / MXene)-5 to 20 ppm CO is only 0.6%. It shows that the metal carbonitride form optimizes the sensing performance of the gas sensing material.

[0188] In Example 1 and Example 6, the (Ni-N-C / MXene)-1 and (Ni-Fe-N-C / MXene)-6 composite materials were prepared. These two composite materials are metal single-atom composite material and metal dual-atom composite material respectively. It can be seen that the response value of (Ni-N-C / MXene)-1 to 20 ppm CO is 43.1%, while the response value of (Ni-Fe-N-C / MXene)-6 to 20 ppm CO is 37.5%; at the same time, the response time of (Ni-Fe-N-C / MXene)-6 is longer, but the recovery time is shorter. It shows that after a part of Ni atoms in the composite material are replaced by Fe atoms, the gas sensing performance for CO is not improved. The reason is that Ni atoms have a good selective response effect on CO, while the response of Fe atoms to CO is not as good as that of Ni atoms.

[0189] In Example 1 and Example 7, the (Ni-N-C / MXene)-1 and (Ni-N-S-C / MXene)-7 composite materials were prepared. Sulfur element was doped in the (Ni-N-S-C / MXene)-7 composite material. It can be seen that the response value of (Ni-N-C / MXene)-1 to 20 ppm CO is 43.1%, while the response value of (Ni-N-S-C / MXene)-7 to 20 ppm CO is 45.6%; at the same time, the recovery time of (Ni-N-S-C / MXene)-7 is shortened. It shows that the NiN 3 S active sites have higher reactivity than NiN 4 Therefore, the gas sensing material can be purposefully modified by adding doping elements.

[0190] The above examples show that the gas sensing material provided by this application has good response sensitivity and selectivity to gases. Further, the above gas sensing material was tested for gas sensing in an oxygen-free environment at room temperature. Compared with the existing materials that require high temperature and the participation of oxygen to have gas response, the conditions are milder and the application range is wider.

[0191] In some embodiments of this application, the gas sensor provided by this application can be used for detecting the gas inside the battery. That is, this application provides a battery, and the battery includes the gas sensor of the above embodiments.

[0192] Please refer to Figure 17 , Figure 17Exploded structural schematic diagram of a battery according to one or more embodiments. The battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are accommodated in the box body 10. Among them, the box body 10 is used to provide an accommodation space for the battery cells 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define an accommodation space for accommodating the battery cells 20. The second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure. The first part 11 covers the open side of the second part 12 so that the first part 11 and the second part 12 jointly define an accommodation space; the first part 11 and the second part 12 may also both be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc. The gas sensor can be installed inside the box body 10.

[0193] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 can be connected in series, parallel, or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells 20 is accommodated in the box body 10; of course, the battery 100 can also be that multiple battery cells 20 are first connected in series, parallel, or in a mixed connection to form a battery module form, and then multiple battery modules are connected in series, parallel, or in a mixed connection to form a whole and are accommodated in the box body 10. The battery 100 may further include other structures. For example, the battery 100 may further include a busbar component for realizing the electrical connection among the multiple battery cells 20.

[0194] Among them, each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc.

[0195] Please refer to Figure 18 , Figure 18 for an exploded structural schematic diagram of a battery cell according to one or more embodiments. The battery cell 20 refers to the smallest unit that makes up a battery. As Figure 18 shown, the battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0196] The end cap 21 refers to a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the housing 22 to cooperate with the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 21 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminals 21a can be used for electrical connection with the electrode assembly 23 to output or input the electrical energy of the battery cell 20. In some embodiments, a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold can also be provided on the end cap 21. The material of the end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this. In some embodiments, an insulating member can also be provided on the inner side of the end cap 21, and the insulating member can be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0197] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, the electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 is covered on the opening to form the internal environment of the battery cell 20. Without limitation, the end cap 21 and the housing 22 can also be integrated. Specifically, the end cap 21 and the housing 22 can first form a common connection surface before other components are put into the housing, and when it is necessary to encapsulate the inside of the housing 22, the end cap 21 is then covered on the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this.

[0198] The electrode assembly 23 is a component in the battery cell 100 where an electrochemical reaction occurs. The housing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or laminating a positive electrode sheet and a negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute the main body of the electrode assembly, and the portions of the positive electrode sheet and the negative electrode sheet without active materials respectively constitute the electrode tabs 23a. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the electrode tabs 23a are connected to the electrode terminals to form a current loop.

[0199] In one embodiment, the positive electrode plate includes a current collector and a positive electrode active layer provided on the current collector.

[0200] The positive electrode active layer includes a positive electrode active material, and the positive electrode active material may include at least one of the following materials: lithium phosphate with an olivine structure, lithium transition metal oxides, 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 transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), 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 O 2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (which can also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn0.1 O 2 (which can also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ), etc., and at least one of its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (which can also be abbreviated as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), composites of lithium manganese phosphate and carbon, lithium manganese iron phosphate, composites of lithium manganese iron phosphate and carbon, etc.

[0201] In one embodiment, the positive electrode active layer further includes a conductive agent to endow the electrode with conductivity. The positive electrode conductive material can include any conductive material as long as it does not cause chemical changes. Non-limiting examples of the positive electrode conductive material include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof. Optionally, the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, Ketjen black, and acetylene black.

[0202] In one embodiment, the positive electrode active layer further includes a binder to improve the adhesion stability of the active layer and reduce the probability of powder falling off. The binder can be one or several of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). Optionally, the binder includes one or several of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

[0203] In one embodiment, the positive electrode active layer further includes other optional additives, and the other optional additives can be thickening and dispersing agents (such as sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.

[0204] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer provided on at least one surface of the negative electrode current collector, and the negative electrode active layer includes a negative electrode active material. In this embodiment, the battery cell is an ion battery. During the charge and discharge process of the battery, active ions (such as Li + , Na+ )Inserted / extracted in the negative electrode active material.

[0205] 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 layer can be disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0206] In one embodiment, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be obtained 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 a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0207] The negative electrode active layer includes a negative electrode active material, and the negative electrode active material includes but is not limited to carbon-based negative electrode materials, silicon-based negative electrode materials, tin-based negative electrode materials, lithium titanate negative electrode materials, metallic lithium negative electrode materials, etc.; specifically includes but is not limited to graphite materials, silicon-carbon materials, graphite-silicon monoxide materials, nanosilicon materials, silicon monoxide materials, and tin-based materials; more specifically includes natural graphite, artificial graphite, mesocarbon microbeads (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO 2 , lithiated TiO with a spinel structure 2 -Li 4 Ti 5 O 12 , one or several of Li-Al alloys.

[0208] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a carbon-containing coating disposed on at least one surface of the negative electrode current collector. In this embodiment, the battery cell is a metal battery. During the charge and discharge process of the battery, active ions are deposited / stripped at the negative electrode sheet. The metal battery can be an alkali metal battery, such as one of a lithium metal battery, a sodium metal battery, a potassium metal battery, a zinc metal battery, and an aluminum metal battery. This type of battery can also be called a "non-negative electrode battery". During charging, relying on the active ions (such as Na + ) extracted from the positive electrode active material are deposited on the negative electrode current collector to form sodium metal. The setting of the carbon-containing coating is beneficial to make the metal deposition more uniform. The carbon-containing material includes one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes.

[0209] In some other embodiments, a conductive film layer may also be deposited on the negative electrode current collector. For example, alloy materials, titanium-based materials, active metals (such as sodium metal), carbon-based materials deposited with metals, metal-containing composite materials, metal-containing alloy materials, etc. The above alloy materials include but are not limited to sodium-tin alloy, sodium-germanium alloy, and sodium-antimony alloy. The above titanium-based materials include but are not limited to titanium dioxide, titanate, and titanium phosphate.

[0210] In some embodiments, the negative electrode active layer may further include a binder, a conductive agent, and other optional additives. As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. As an example, the binder may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). As an example, other optional additives may be thickening and dispersing agents (such as sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.

[0211] In some embodiments, the material of the separator may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0212] In one embodiment, the electrolyte includes one or more of carbonate solvents and ether solvents.

[0213] Carbonates are usually small-molecule cyclic or chain carbonates; including but not limited to one or more of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methyl propyl carbonate, dipropyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and fluorinated carbonate; it may also be at least one ester solvent of γ-butyrolactone, dimethyl sulfite, ethyl acetate, methyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate, and fluorinated carboxylate.

[0214] Ether solvents include, but are not limited to, one or more of dimethyl ether, diethyl ether, tetrahydrofuran, methyltetrahydrofuran, ethylene oxide, 1,3-dioxolane, fluoroethers, DME (ethylene glycol dimethyl ether), DEE (ethylene glycol diethyl ether), DEGDME (diethylene glycol dimethyl ether), TRGDME (triethylene glycol dimethyl ether), TEGDME (tetraethylene glycol dimethyl ether), dipropyl ether, and dibutyl ether.

[0215] In other embodiments, the electrolyte may further include a mixture composed of any one or several of amine solvents, sulfone solvents, and nitrile solvents. Amine solvents include at least one of N-methylacetamide, N-methylformamide, dimethylformamide, and diethylformamide. Sulfone solvents include at least one of dimethyl sulfoxide, sulfolane, diphenyl sulfoxide, thionyl chloride, and dipropyl sulfone. Nitrile solvents include at least one of acetonitrile, succinonitrile, adiponitrile, and glutaronitrile. The electrolyte preferably is a high-voltage-resistant electrolyte, whose acidity weakens under high voltage, which is beneficial to the transport of active ions, significantly reduces side reactions on the electrode surface, and improves battery stability.

[0216] In some embodiments, the electrolyte further includes an electrolyte salt, and the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0217] In some embodiments, the electrolyte may optionally further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performances, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0218] The battery disclosed in the embodiments of the present application can be used in electrical equipment using the battery as a power source or various energy storage systems using the battery as an energy storage element. That is, the present application provides an electrical equipment, and the electrical equipment includes the battery of the above embodiments. In some embodiments, the electrical equipment of the present application can be used in, but is not limited to, laptop computers, pen input computers, mobile computers, e-book players, mobile phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, liquid crystal TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, motorized bicycles, bicycles, ships, spacecrafts, lighting appliances, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries, and lithium-ion capacitors, etc.

[0219] The electrical equipment can select battery cells, battery modules or battery packs according to its usage requirements.

[0220] Please refer to Figure 19 , Figure 19 which is a schematic structural diagram of a vehicle according to one or more embodiments. The 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 or an extended-range vehicle, etc. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to supply power to the vehicle 1000. For example, the battery 100 can be used as the operating power source of the vehicle 1000. The vehicle 1000 may 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 the vehicle 1000.

[0221] In some embodiments of the present application, the battery 100 can not only be used as the operating power source of the vehicle 1000, but also be used as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000. In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0222] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A gas sensing material, characterized in that, it comprises: an M / MXene composite material, wherein the M / MXene composite material includes metal (M) single atoms and MXene material; and / or the M / MXene composite material includes metal (M) clusters and MXene material.

2. The gas sensing material according to claim 1, characterized in that, the M / MXene composite material includes metal (M) carbonitride, and the metal carbonitride is loaded on the surface of the MXene material.

3. The gas sensing material according to claim 2, characterized in that, each metal atom M in the metal carbonitride is respectively bonded to four nitrogen atoms.

4. The gas sensing material according to claim 3, characterized in that, the metal carbonitride includes a graphite structure, the nitrogen atoms bonded with the metal atoms M are embedded in the graphite structure and are bonded to the carbon atoms of the graphite structure, and the graphite structure is combined on the surface of the MXene material.

5. The gas sensing material according to any one of claims 2 to 4, characterized in that, the metal carbonitride is doped with element X, and X includes one or more of sulfur, phosphorus, and boron.

6. The gas sensing material according to claim 5, characterized in that, each metal atom M in the metal carbonitride is respectively bonded to four nitrogen atoms, and the doped element X replaces one or more of the four nitrogen atoms bonded to the metal atom M.

7. The gas sensing material according to claim 1, characterized in that, the metal (M) single atoms in the M / MXene composite material are embedded in the structure of the MXene material.

8. The gas sensing material according to any one of claims 1 to 7, characterized in that, the metal M includes one or more of Fe, Co, Ni, Mn, Cu, Zn, Cr, Pd, Pt, Au, Ag, Ir, Ru; optionally, the metal M includes one or more of Fe, Co, Ni.

9. The gas sensing material according to any one of claims 1 to 8, characterized in that, the size of the metal (M) single atoms in the M / MXene composite material is less than 1 nm, optionally less than 0.5 nm; and / or the size of the metal (M) clusters in the M / MXene composite material is 1 - 50 nm, optionally 10 - 30 nm.

10. The gas sensing material according to any one of claims 1 to 9, characterized in that, based on the total number of atoms of the M / MXene composite material, the atomic content (at%) of the metal M element is less than or equal to 15%; optionally, the atomic content (at%) of the metal M element is less than or equal to 10%; optionally, the atomic content (at%) of the metal M element is less than or equal to 5%.

11. The gas sensing material according to any one of claims 1 to 10, characterized in that, The MXene material includes M’ n+1 X’ n T x , where M’ is an early transition metal element, X’ is carbon or nitrogen element, and T x is OH - 、O 2- 、F - or any one of the groups.

12. The gas sensing material according to any one of claims 1 to 11, characterized in that, The response gases of the gas sensing material include CO, NO 2 , NO, H 2 , CH 4 , H 2 S, ethylene, ethane, volatile organic compounds, one or more of volatile electrolytes; Optionally, the volatile organic compound includes at least one of methanol, formaldehyde, toluene, styrene, phenol, and benzene; Optionally, the volatile electrolyte includes at least one of polyether electrolytes and polyester electrolytes.

13. The gas sensing material according to any one of claims 1 to 12, characterized in that the gas sensing material has a sensing response to gases in the range of -55°C to 65°C.

14. A method for preparing a gas sensing material, characterized in that it includes: providing a composite of MXene and a metal-organic complex, where the metal-organic complex is a complex of metal M and an organic ligand; calcining the composite to obtain an M / MXene composite material, where the M / MXene composite material includes single atoms of metal (M) and MXene material; and / or the M / MXene composite material includes clusters of metal (M) and MXene material.

15. The method for preparing a gas sensing material according to claim 14, characterized in that the calcining of the composite includes: the temperature of the calcining is 700 - 1000°C, preferably 850 - 950°C; and / or the time of the calcining is 1 - 4 h.

16. The method for preparing a gas sensing material according to claim 14 or 15, characterized in that the calcining of the composite includes: calcining the composite in an atmosphere of a protective gas, optionally, the protective gas includes one or more of argon, hydrogen, and nitrogen; and / or calcining the composite in an atmosphere of a doping gas, optionally, the doping gas includes one or more of ammonia and hydrogen sulfide.

17. The method for preparing a gas sensing material according to any one of claims 14 to 16, characterized in that the providing of the composite of MXene and a metal-organic complex includes: mixing a metal-organic complex solution and an MXene solution, and stirring and reacting to obtain the composite.

18. The method for preparing a gas sensing material according to claim 17, characterized in that the mixing of the metal-organic complex solution and the MXene solution includes: dropping the MXene solution into the stirring metal-organic complex solution; optionally, the dropping rate of the MXene solution is 1 - 20 drops / second.

19. The method for preparing a gas sensing material according to claim 17 or 18, characterized in that before the mixing of the metal-organic complex solution and the MXene solution includes: combining the metal-organic complex with a surfactant; and / or combining the MXene solution with a surfactant.

20. The method for preparing a gas sensing material according to claim 19, characterized in that the surfactant includes cetyltrimethylammonium bromide.

21. The method for preparing a gas sensing material according to claim 20, characterized in that the combining of the metal-organic complex with the surfactant includes: providing a metal-organic complex precursor and cetyltrimethylammonium bromide; Mix the metal-organic complex precursor with cetyltrimethylammonium bromide and react to obtain a metal-organic complex combined with cetyltrimethylammonium bromide.

22. The preparation method of the gas sensing material according to any one of claims 17 to 21, characterized in that, before mixing the metal-organic complex solution with the MXene solution, it includes: providing a metal-organic complex precursor and a doping precursor; mixing the metal-organic complex precursor with the doping precursor and reacting to obtain a metal-organic complex with a doping element.

23. A preparation method of a gas sensing material, characterized in that, it includes: etching the MXene material precursor to obtain an MXene material with defect vacancies; composite-reacting a metal-organic complex with the MXene material with defect vacancies to obtain an M / MXene composite material, and the M / MXene composite material includes metal (M) single atoms and MXene materials; and / or the M / MXene composite material includes metal (M) clusters and MXene materials.

24. A gas sensor, characterized in that, it includes the gas sensing material according to any one of claims 1 to 13; or it includes the gas sensing material prepared by using the method according to any one of claims 14 to 23.

25. A battery, characterized in that, it includes the gas sensor according to claim 24.

26. An electrical device, characterized in that, it includes the battery according to claim 25.

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