Lithium metal battery cell and preparation method therefor, preparation method for positive electrode sheet, battery apparatus and electrical apparatus

Abstract

Provided are a lithium metal battery cell and a preparation method therefor, a preparation method for a positive electrode sheet, a battery apparatus and an electrical apparatus. The lithium metal battery cell comprises a lithium metal negative electrode sheet and a positive electrode sheet; the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material film layer provided on at least one side of the positive electrode current collector; the positive electrode active material film layer comprises a lithium-conducting binder, a lithium salt and a plasticizer; the plasticizer is used for dissociating and / or dispersing the lithium salt; the plasticizer comprises one or more of a sulfone compound, a sulfonamide compound and an aromatic nitrile.

Description

Lithium metal battery cells and their preparation methods, preparation methods of positive electrode sheets, battery devices and electrical devices.

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411214945.3, filed on August 30, 2024, entitled “Lithium Metal Battery Cell and Preparation Method Thereof, Preparation Method of Positive Electrode, Battery Device and Power-Consuming Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of lithium metal battery cell technology, specifically relating to a lithium metal battery cell and its preparation method, a positive electrode preparation method, a battery device, and an electrical device. Background Technology

[0004] As batteries become increasingly widely used, people's demands for their performance are also growing, such as the increasing requirement for higher energy density. Lithium metal batteries are a promising option. Generally speaking, compared to traditional lithium-ion batteries, lithium metal batteries offer higher energy density and longer battery life. With optimized solid-state or semi-solid-state electrolytes, they can operate over a wider temperature range.

[0005] Lithium metal batteries use lithium metal as the negative electrode and employ solid or semi-solid electrolytes instead of traditional liquid electrolytes and separators. This has a certain impact on the dynamic performance of lithium metal batteries, and therefore needs to be addressed. Summary of the Invention

[0006] The purpose of this application is to provide a lithium metal battery cell and its preparation method, as well as a method for preparing a positive electrode sheet. The positive electrode sheet's positive active material film layer includes a lithium-conducting binder, a lithium salt, and a plasticizer, constructing a high-concentration lithium-ion region and a high-speed ion conduction channel, thereby improving the kinetic performance of the lithium metal battery cell and its cycle life. Battery devices and power-consuming devices incorporating this lithium metal battery cell have at least the aforementioned beneficial effects.

[0007] In a first aspect, embodiments of this application provide a lithium metal battery cell, including a lithium metal negative electrode and a positive electrode. The positive electrode includes a positive current collector and a positive active material film layer disposed on at least one side of the positive current collector. The positive active material film layer includes a lithium-conducting binder, a lithium salt, and a plasticizer. The plasticizer is used to dissociate and / or disperse the lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

[0008] In the embodiments of this application, the electron-rich functional groups in plasticizer sulfone compounds, sulfonamide compounds, and aromatic nitriles interact with the lithium salt cations, promoting the dissociation of lithium salt and forming a localized high-concentration lithium ion region in situ, thus constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film. The lithium-conducting binder included in the positive electrode active material film can also participate in the dissociation of lithium salt, and together with the plasticizer, they construct a high-speed ion conduction channel network, thereby improving the kinetic performance of the lithium metal battery cell.

[0009] In the embodiments of this application, the positive electrode active material film layer includes a plasticizer, which is used to dissociate and / or disperse lithium salt. Due to the presence of the plasticizer, the oxidation stability of the positive electrode active material film layer is improved, the interfacial side reactions between the positive electrode sheet and the electrolyte are suppressed, and the cycle life of the lithium metal battery cell is improved.

[0010] Before use, the plasticizer of a lithium metal battery cell needs to be activated or heated to transform it into a gel and / or liquid state. This treatment can be performed at the positive electrode layer or at the lithium metal battery cell layer.

[0011] In some optional embodiments, in order to promote the dissociation of lithium ions in the lithium salt, a region with a local high concentration of lithium ions is formed in situ, a high-speed ion conduction channel is constructed, and the ionic conductivity of the positive electrode active material film is improved. Based on the total mass of the positive electrode active material film, the mass content of the plasticizer is 0.5% to 10%.

[0012] In some optional embodiments, the plasticizer content is 2% to 5% by mass, based on the total mass of the positive electrode active material film. Therefore, an appropriate amount of plasticizer can achieve a balance between battery energy density and the ionic conductivity of the positive electrode active material film. The presence of the plasticizer improves the oxidative stability between the positive electrode active material film and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell.

[0013] In some alternative embodiments, the plasticizer includes one or more of cyano, sulfur-oxygen double bond, and carbonyl.

[0014] In this embodiment, cyano (C≡N bond), sulfur-oxygen double bond (S=O bond), and carbonyl (C=O) groups have high electron density and / or negative charge (lone pair electrons), which can effectively solubilize lithium ions, promote the dissociation of lithium salt, or effectively reduce the lattice energy of lithium salt, making lithium salt easier to dissociate, improving the degree of dissociation of lithium salt, and comprehensively improving the mobility of lithium ions and the dynamic performance of the battery.

[0015] In some alternative embodiments, the plasticizer includes one or more of dimethyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, methanesulfonamide, sulfonamide, ethyl sulfonamide, propyl sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, fluorophenyl sulfone, ethyl methyl sulfone, 3-cyanopyridine, 2-cyanophenylacetonitrile, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0016] In some optional embodiments, the plasticizer is a solid particle with an average volume particle size Dv50 of 0.1 μm to 3 μm.

[0017] In this embodiment, before activation, the plasticizer in the lithium metal battery cell can be solid particles. Solid particles of plasticizer can be more uniformly dispersed in the positive electrode active material film, improving the ionic conductivity of the positive electrode active material film and thus enhancing the kinetic performance of the lithium metal battery cell. The presence of the plasticizer further improves the oxidative stability between the positive electrode active material film and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell.

[0018] In some optional embodiments, the plasticizer is uniformly dispersed in the positive electrode active material film layer. The uniform dispersion of the plasticizer in the positive electrode active material film layer improves the ionic conductivity of the film layer and enhances the kinetic performance of the lithium metal battery cell. The presence of the plasticizer further improves the oxidative stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell.

[0019] In some optional embodiments, the positive electrode active material film layer includes a porous material, which includes one or more of aerogels, molecular sieve porous organic frameworks, and porous metal-organic frameworks.

[0020] The active sites on the surface of porous materials promote the dissociation of lithium salts, which in turn promotes the interaction between plasticizers and lithium salt cations, further promoting the dissociation of lithium salts. This comprehensively constructs high-speed ion conduction channels and improves the ionic conductivity of the positive electrode active material film.

[0021] In the embodiments of this application, the porous characteristics of the porous material can accommodate the activated plasticizer, restrict the flow of the plasticizer, and make at least part of the surface of the porous material in a gel state, which comprehensively improves the stability of the positive electrode active material film and improves the cycle life of the lithium metal battery cell; the plasticizer and dissociated lithium ions in the pores of the porous material also form a high-concentration lithium ion region, constructing a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0022] The active sites on the surface of porous materials promote the dissociation of lithium salts, further facilitating the interaction between plasticizers and lithium salt cations, thus comprehensively constructing high-speed ion conduction channels and improving the ionic conductivity of the positive electrode active material film. For example, amino (-NH2), carboxyl (-COOH), or sulfonic acid (-SO3H) groups on the surface of porous materials can promote the dissociation of lithium ions by forming hydrogen bonds or through acid-base interactions. For instance, metal / non-metal ions (such as zinc, copper, aluminum, silicon, etc.) in MOFs, aerogels, and molecular sieves have different oxidation states and coordination environments. These unsaturated metal sites can interact with lithium salt anions, thereby promoting the dissociation of lithium ions and enhancing their migration ability.

[0023] In the embodiments of this application, the porous characteristics of the porous material can accommodate the activated plasticizer, restrict the flow of the plasticizer, and make at least part of the surface of the porous material in a gel state, which comprehensively improves the stability of the positive electrode active material film and improves the cycle life of the lithium metal battery cell; the plasticizer and dissociated lithium ions in the pores of the porous material also form a high-concentration lithium ion region, constructing a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0024] In some optional embodiments, the mass content of porous material is 0.5% to 3% based on the total mass of the positive electrode active material film. A mass content of porous material within this range can improve the structural stability and porosity of the positive electrode active material film. The active sites on the surface of the porous material promote the dissociation of lithium salt, increasing the ionic conductivity of the positive electrode active material film. The plasticizers and dissociated lithium ions within the pores of the porous material also create high-concentration lithium-ion regions, constructing high-speed ion conduction channels and further improving the kinetic performance of the lithium metal battery cell.

[0025] In some optional embodiments, the average pore size of the porous material is 0.3 nm to 50 nm. An average pore size within this range can effectively confine the activated liquid plasticizer. The plasticizer and dissociated lithium ions in the pores also create a high-concentration lithium-ion region, constructing a high-speed ion conduction channel and further improving the kinetic performance of the lithium metal battery cell.

[0026] In some optional embodiments, the porosity of the porous material is 80% to 99.8%. Therefore, the porous material can accommodate the activated liquid plasticizer and lithium ions, which is beneficial for constructing lithium ion conduction pathways and further improving the kinetic performance of lithium metal battery cells.

[0027] In some optional embodiments, the porous material is in particulate form, and the volume average particle size Dv50 of the porous material is 1 μm to 6 μm. Therefore, the volume average particle size Dv50 of the porous material is within the above range, which can be uniformly dispersed in the positive electrode active material film layer, promote the dissociation of lithium salt, improve the stability of the positive electrode active material film layer, and improve the cycle life of the lithium metal battery cell.

[0028] In some alternative embodiments, the lithium-conducting binder includes one or more of polyacrylonitrile and polycaprolactone.

[0029] Lithium-conducting binders possess high electron density and / or negatively charged (lone pair) groups, such as cyano (C≡N bond) and / or carbonyl (C=O), which can participate in the dissociation of lithium salts, providing conduction channels for lithium ions to jump along these group sites. Furthermore, lithium-conducting binders, lithium salts, and plasticizers together construct a high-concentration lithium-ion region, building a high-speed ion conduction channel and improving the kinetic performance of lithium metal battery cells. Lithium-conducting binders can improve the interfacial stability between the electrode and the electrolyte, reducing electrode surface instability and electrolyte decomposition problems. Thanks to the good oxidation resistance of lithium-conducting binders, they can improve the cycle life and interfacial stability of lithium metal battery cells.

[0030] In some optional embodiments, the mass content of the lithium-conducting binder is 0.5% to 10%, optionally 1% to 3%, based on the total mass of the positive electrode active material film.

[0031] The mass content of lithium-conducting binders in the above range can further improve the kinetic performance of lithium metal battery cells; lithium-conducting binders can improve the interfacial stability between the electrode and the electrolyte, and can improve the cycle life and stability of lithium metal battery cells.

[0032] In some optional embodiments, the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0033] In some optional embodiments, the mass content of lithium salt is 1% to 10%, optionally 2% to 6%, based on the total mass of the positive electrode active material film.

[0034] In some optional embodiments, the positive electrode active material film layer comprises 80% to 96% positive electrode active material, which includes one or more of lithium-containing transition metal oxides and lithium-containing transition metal phosphates.

[0035] In some optional embodiments, the ionic conductivity of the positive electrode is 1×10⁻⁶. -4 The ionic conductivity of the positive electrode is within the range of S / cm to 1S / cm. Therefore, the kinetic performance of the lithium battery cell can be improved when the ionic conductivity of the positive electrode is within the above range.

[0036] In some optional embodiments, the positive electrode active material film layer includes a conductive agent, which includes long-range conductive carbon and short-range conductive carbon.

[0037] Long-range conductive carbon usually refers to carbon materials that have high conductivity and can form a continuous conductive network in electrode materials, such as carbon fibers and carbon nanotubes.

[0038] In this embodiment, long-range conductive carbon provides a long-distance electron conduction path and forms a continuous conductive network, improving the conductivity of the entire electrode. Long-range conductive carbon provides structural support and can reduce the cracking or pulverization of electrode materials caused by volume changes during battery charging and discharging, reduce material loss and capacity decay, and improve the cycle life of lithium metal battery cells.

[0039] Short-range conductive carbon usually refers to carbon materials that have good conductivity but cannot form long-distance conductive networks, such as carbon black and acetylene black.

[0040] In this embodiment, short-range conductive carbon provides local electron conduction, fills the micropores and small gaps in the electrode material, provides additional surface area, facilitates full contact between the electrode material and the electrolyte, improves the local conductivity of the positive electrode, enhances reactivity, increases the rate of electrochemical reaction, improves the uniformity of the electrode material, reduces the uneven distribution of current density, and improves the electrochemical performance of the lithium metal battery cell.

[0041] The combined use of long-range and short-range conductive carbon can provide an overall conductive network, improving the conductivity and mechanical strength of the positive electrode, as well as filling micropores, improving local conductivity, increasing reactivity, and enhancing material uniformity, thereby comprehensively improving the energy density, cycle life, and kinetic performance of lithium metal battery cells.

[0042] In some optional embodiments, the mass content of the conductive agent is 0.5% to 3% based on the total mass of the positive electrode active material film.

[0043] In some optional embodiments, the mass ratio of long-range conductive carbon to short-range conductive carbon is 1:(0.5 to 5).

[0044] In this embodiment, the mass ratio of long-range conductive carbon to short-range conductive carbon is within the above range, which constructs a good conductive network, improves the conductivity and mechanical strength of the positive electrode sheet, fills micropores, improves local conductivity, increases reactivity, improves material uniformity, and comprehensively improves the energy density, cycle life and kinetic performance of lithium metal battery cells.

[0045] In some alternative embodiments, the long-range conductive carbon includes one or more of vapor-grown carbon fibers and carbon nanotubes.

[0046] In some alternative embodiments, the short-range conductive carbon includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, and carbon dots.

[0047] In some optional embodiments, the lithium metal battery cell includes a solid electrolyte, which includes one or more of oxide-based solid electrolytes, sulfide-based solid electrolytes, polyethylene oxide electrolytes, and organic-inorganic composite electrolytes composed of polyethylene oxide and inorganic substances.

[0048] In this embodiment, the solid electrolyte typically possesses high mechanical strength, which can effectively suppress the growth of lithium dendrites and reduce the risk of battery short circuits. The solid component reduces direct contact with lithium metal, minimizing adverse reactions between the electrolyte and lithium metal, improving the interfacial compatibility and stability between the electrolyte and electrode materials, and enhancing the battery's cycle stability. Furthermore, the solid electrolyte exhibits good ionic conductivity, improving the kinetic performance of the lithium metal battery cell.

[0049] In some optional embodiments, the lithium metal battery cell includes a semi-solid electrolyte; the semi-solid electrolyte includes one or more of the following: polyvinylidene fluoride-hexafluoropropylene copolymer gel electrolyte, polyvinylidene fluoride (PVDF) containing liquid organic solvent, polyethylene oxide (PEO) containing liquid organic solvent, polyacrylonitrile (PAN) containing liquid organic solvent, polymethyl methacrylate (PMMA) based gel electrolyte; and covalent organic framework based gel electrolyte containing ionic liquid electrolyte.

[0050] In this embodiment, the semi-solid electrolyte can improve the interfacial compatibility and stability between the electrolyte and electrode materials, improve the cycle stability of the battery, improve the ionic conductivity of the lithium metal battery cell, and improve the kinetic performance of the lithium metal battery cell.

[0051] Secondly, embodiments of this application provide a method for preparing a positive electrode sheet for a lithium metal battery cell, comprising:

[0052] A positive electrode active material slurry is coated on a positive electrode current collector to obtain an initial positive electrode sheet. The positive electrode active material slurry includes a plasticizer, a lithium binder, and a lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

[0053] The initial positive electrode sheet is heated to transform the plasticizer into a gel phase and / or liquid state to obtain the positive electrode sheet.

[0054] In the preparation method of this application embodiment, when the plasticizer is in the gel phase and / or liquid phase, the electron-rich functional groups of the plasticizer interact with the cations of the lithium salt, promoting the dissociation of the lithium salt and forming a region with a local high concentration of lithium ions in situ, thus constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film layer. Furthermore, the lithium-conducting binder, lithium salt, and plasticizer included in the positive electrode active material film layer construct a high-concentration lithium ion region, constructing a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0055] In the embodiments of this application, the positive electrode active material film layer includes a plasticizer, which is used to dissociate and / or disperse lithium salt. Due to the presence of the plasticizer, the oxidation stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell is improved, the interfacial side reactions between the positive electrode and the electrolyte are suppressed, and the cycle life of the lithium metal battery cell is improved.

[0056] In some optional embodiments, the plasticizer is one or more of the following: dimethyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, methanesulfonamide, sulfonamide, ethyl sulfonamide, propyl sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, ethyl methanesulfonate, fluorophenyl sulfone, ethyl methyl sulfone, 3-cyanopyridine, 2-cyanophenylacetonitrile, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0057] In some optional embodiments, the plasticizer is a solid particle with an average volume particle size Dv50 of 0.1 μm to 3 μm.

[0058] In some optional embodiments, the melting point T of the plasticizer satisfies: 25°C < T ≤ 120°C, and the heating temperature is greater than the melting point of the plasticizer.

[0059] In the embodiments of this application, the melting point T of the plasticizer is within the above range, which enables it to be a solid plasticizer at room temperature. However, after heat treatment at a certain temperature, it can be melted into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ. This constructs a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and enhances the dynamic performance of the battery.

[0060] In some alternative embodiments, the plasticizer includes one or more of dimethyl sulfone, diethyl sulfone, methanesulfonamide, sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, and cyanophenylacetonitrile.

[0061] In the embodiments of this application, the solid particulate plasticizer can be solid at room temperature, but after heat treatment at a certain temperature, it can melt into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ, constructing a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and improves the dynamic performance of the battery.

[0062] In the embodiments of this application, high-speed ion conduction channels are combined with solid electrolytes or semi-solid electrolytes to improve battery rate performance.

[0063] Thirdly, embodiments of this application provide a method for preparing a lithium metal battery cell, comprising:

[0064] An initial positive electrode sheet is provided, which includes a positive current collector and an initial positive active material film layer. The initial positive active material film layer includes a plasticizer, a lithium binder, and a lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

[0065] The initial positive electrode sheet is assembled with the lithium metal negative electrode sheet and the electrolyte to obtain the initial lithium metal battery cell.

[0066] The initial lithium metal battery cell is heated to transform the plasticizer into a gel phase and / or liquid phase to obtain the lithium metal battery cell.

[0067] In the preparation method of this application embodiment, when the plasticizer is in the gel phase and / or liquid phase, the electron-rich functional groups of the plasticizer interact with the cations of the lithium salt, promoting the dissociation of the lithium salt and forming a region with a local high concentration of lithium ions in situ, thus constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film layer. Furthermore, the lithium-conducting binder, lithium salt, and plasticizer included in the positive electrode active material film layer construct a high-concentration lithium ion region, construct a high-speed ion conduction channel, suppress the interfacial side reactions between the positive electrode sheet and the electrolyte, and further improve the kinetic performance of the lithium metal battery cell.

[0068] In the embodiments of this application, the positive electrode active material film layer includes a plasticizer, which is used to dissociate and / or disperse lithium salt. Due to the presence of the plasticizer, the oxidation stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell is improved, thereby improving the cycle life of the lithium metal battery cell.

[0069] In some optional embodiments, the melting point T of the plasticizer satisfies: 25℃≤T≤60℃.

[0070] In the embodiments of this application, the plasticizer has a low melting point and can be a solid plasticizer at room temperature. However, after heat treatment at a certain temperature, it can melt into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ. This constructs a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and enhances the dynamic performance of the battery.

[0071] In some alternative embodiments, the plasticizer includes one or more of dipropyl sulfone, sulfolane, fluorophenyl sulfone, ethyl sulfonamide, propyl sulfonamide, ethyl methanesulfonate, cyanopyridine, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0072] In some optional embodiments, the plasticizer is a solid particle with an average volume particle size Dv50 of 0.1 μm to 3 μm.

[0073] In the embodiments of this application, the solid particulate plasticizer can be solid at room temperature, but after heat treatment at a certain temperature, it can melt into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ, constructing a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and improves the dynamic performance of the battery.

[0074] In some optional embodiments, the positive electrode active material film layer includes a porous material, which includes one or more of aerogels, molecular sieve porous organic frameworks, and porous metal-organic frameworks.

[0075] The active sites on the surface of porous materials promote the dissociation of lithium salts, which in turn promotes the interaction between plasticizers and lithium salt cations, further promoting the dissociation of lithium salts. This comprehensively constructs high-speed ion conduction channels and improves the ionic conductivity of the positive electrode active material film.

[0076] In the embodiments of this application, the porous characteristics of the porous material can accommodate the activated plasticizer, restrict the flow of the plasticizer, and make at least part of the surface of the porous material in a gel state, which comprehensively improves the stability of the positive electrode active material film and improves the cycle life of the lithium metal battery cell; the plasticizer and dissociated lithium ions in the pores of the porous material also form a high-concentration lithium ion region, constructing a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0077] The active sites on the surface of porous materials promote the dissociation of lithium salts, further facilitating the interaction between plasticizers and lithium salt cations, thus comprehensively constructing high-speed ion conduction channels and improving the ionic conductivity of the positive electrode active material film. For example, amino (-NH2), carboxyl (-COOH), or sulfonic acid (-SO3H) groups on the surface of porous materials can promote the dissociation of lithium ions by forming hydrogen bonds or through acid-base interactions. For instance, metal / non-metal ions (such as zinc, copper, aluminum, silicon, etc.) in MOFs, aerogels, and molecular sieves have different oxidation states and coordination environments. These unsaturated metal sites can interact with lithium salt anions, thereby promoting the dissociation of lithium ions and enhancing their migration ability.

[0078] In the embodiments of this application, the porous characteristics of the porous material can accommodate the activated plasticizer, restrict the flow of the plasticizer, and make at least part of the surface of the porous material in a gel state, which comprehensively improves the stability of the positive electrode active material film and improves the cycle life of the lithium metal battery cell; the plasticizer and dissociated lithium ions in the pores of the porous material also form a high-concentration lithium ion region, constructing a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0079] In some optional embodiments, the mass content of porous material is 0.5% to 3% based on the total mass of the positive electrode active material film. A mass content of porous material within this range can improve the structural stability and porosity of the positive electrode active material film. The active sites on the surface of the porous material promote the dissociation of lithium salt, increasing the ionic conductivity of the positive electrode active material film. The plasticizers and dissociated lithium ions within the pores of the porous material also create high-concentration lithium-ion regions, constructing high-speed ion conduction channels and further improving the kinetic performance of the lithium metal battery cell.

[0080] In some optional embodiments, the average pore size of the porous material is 0.3 nm to 50 nm. An average pore size within this range can effectively confine the activated liquid plasticizer. The plasticizer and dissociated lithium ions in the pores also create a high-concentration lithium-ion region, constructing a high-speed ion conduction channel and further improving the kinetic performance of the lithium metal battery cell.

[0081] In some optional embodiments, the porosity of the porous material is 80% to 99.8%. Therefore, the porous material can accommodate the activated liquid plasticizer and lithium ions, which is beneficial for constructing lithium ion conduction pathways and further improving the kinetic performance of lithium metal battery cells.

[0082] In some optional embodiments, the porous material is in particulate form, and the volume average particle size Dv50 of the porous material is 1 μm to 6 μm. Therefore, the volume average particle size Dv50 of the porous material is within the above range, which can be uniformly dispersed in the positive electrode active material film layer, promote the dissociation of lithium salt, improve the stability of the positive electrode active material film layer, and improve the cycle life of the lithium metal battery cell.

[0083] Fourthly, embodiments of this application provide a battery device comprising a lithium metal battery cell of the first aspect or a lithium metal battery cell prepared by the preparation method of the second aspect. The battery device of this application comprises a lithium metal battery cell of the first aspect or a lithium metal battery cell prepared by the preparation method of the second aspect, and therefore possesses at least the advantages corresponding to a lithium metal battery cell.

[0084] Fifthly, embodiments of this application provide an electrical device, including the battery device of the fourth aspect.

[0085] The electrical device of this application includes the battery device of the fourth aspect of this application, and therefore has at least the advantages corresponding to the battery device. Attached Figure Description

[0086] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0087] Figure 1 shows a schematic diagram of one embodiment of the lithium metal battery cell of this application.

[0088] Figure 2 shows an exploded schematic diagram of one embodiment of the lithium metal battery cell shown in Figure 1.

[0089] Figure 3 shows an overall schematic diagram of a battery pack according to one embodiment of this application.

[0090] Figure 4 shows an exploded view of a battery pack according to one embodiment of this application.

[0091] Figure 5 shows a positive electrode sheet according to one embodiment of this application.

[0092] Figure 6 shows a schematic diagram of one embodiment of an electrical device that uses a lithium metal battery cell as a power source, incorporating the present application.

[0093] Figure 7 shows the impedance curves of the positive electrode sheets of Embodiment 1 and Comparative Example 2 of this application.

[0094] Figure 8 shows the impedance curve of the positive electrode of Comparative Example 1 of this application.

[0095] The accompanying drawings are not necessarily drawn to scale.

[0096] The reference numerals in the attached diagram are explained as follows: 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Lithium battery cell; 520. Positive electrode sheet; 521. Positive current collector; 522. Positive active material film. Detailed Implementation

[0097] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the lithium metal battery cell and its preparation method, the positive electrode preparation method, the battery device, and the power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0098] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0099] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0100] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0101] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0102] Unless otherwise specified, in this application, the terms "first," "second," "third," "fourth," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0103] Unless otherwise specified, in this application, the term "active ion" refers to ions that can be inserted and extracted back and forth between the positive and negative electrodes of a lithium metal battery cell, including but not limited to lithium ions.

[0104] In this application, "multiple" or "more than" refers to two or more items (including two). In this application, "several items" or "multiple items" refers to two or more items (including two).

[0105] The lithium metal battery cell mentioned in the embodiments of this application may be a lithium metal battery cell, etc., and the embodiments of this application are not limited to this.

[0106] The battery device mentioned in the embodiments of this application may include one or more lithium metal battery cells as a single physical module to provide higher voltage and capacity. For example, the battery device mentioned in this application may include lithium metal battery cells, battery modules, or battery packs.

[0107] In some alternative embodiments, the battery device can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc. The battery device mentioned in the embodiments of this application may include one or more lithium metal battery cell assemblies for providing voltage and capacity. A lithium metal battery cell assembly may include multiple lithium metal battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0108] In some alternative embodiments, a lithium metal battery cell assembly is typically formed by arranging multiple lithium metal battery cells; as an example, a lithium metal battery cell assembly can be a battery module, which is formed by arranging and fixing multiple lithium metal battery cells into a single module. As an example, a battery module can be formed by bundling multiple lithium metal battery cells together with cable ties.

[0109] In some alternative embodiments, the battery device may be a battery pack, which may include a housing and one or more lithium metal battery cell assemblies housed within the housing. In some alternative embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0110] As an example, a lithium metal battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0111] As an example, lithium metal battery cell assemblies can also be housed in a housing by directly fixing multiple lithium metal battery cells to the housing.

[0112] A lithium metal battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A lithium metal battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited to this. Figure 1 shows a cuboid lithium metal battery cell 5 as an example.

[0113] When there are multiple lithium metal battery cells, the multiple lithium metal battery cells are connected in series, parallel, or mixed through a busbar. In some optional embodiments, the battery can be a battery module; when there are multiple lithium metal battery cells, the multiple lithium metal battery cells are arranged and fixed to form a battery module.

[0114] In some optional embodiments, lithium metal battery cells can be assembled into a battery module. The number of lithium metal battery cells in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 2 is a schematic diagram of a battery module 4 as an example. As shown in Figure 2, in the battery module 4, multiple lithium metal battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Furthermore, the multiple lithium metal battery cells 5 can be fixed in place using fasteners.

[0115] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple lithium metal battery cells 5 are received.

[0116] In some alternative embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0117] Figures 3 and 4 are schematic diagrams of a battery pack 1 as an example. As shown in Figures 3 and 4, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 and forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0118] The lithium metal battery cells provided in the embodiments of this application can be secondary batteries, primary batteries, etc. A secondary battery is a lithium metal battery cell that can be recharged after discharge to activate the active materials and continue to be used.

[0119] The lithium metal battery cell provided in this application includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode and a negative electrode. The negative electrode can be a lithium metal negative electrode. The electrode assembly can be a wound structure or a stacked structure; this application does not limit this. In some embodiments, the electrode assembly further includes a separator disposed between the positive and negative electrode. In some embodiments, the separator is a separator membrane. This application does not have a particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. In some embodiments, the electrode assembly may not have a separator, and the electrolyte may function as a separator.

[0120] Lithium metal battery cells may also include an outer packaging, which can be used to encapsulate electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0121] This application provides a lithium metal battery cell, including a lithium metal negative electrode and a positive electrode. The positive electrode includes a positive current collector and a positive active material film layer disposed on at least one side of the positive current collector. The positive active material film layer includes a lithium-conducting binder, a lithium salt, and a plasticizer. The plasticizer is used to dissociate and / or disperse the lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

[0122] In the embodiments of this application, the electron-rich functional groups of the plasticizer interact with the cations of the lithium salt, promoting the dissociation of the lithium salt and forming a region with a local high concentration of lithium ions in situ, thus constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film. Furthermore, the lithium-conducting binder included in the positive electrode active material film can also participate in the dissociation of the lithium salt and, together with the plasticizer, construct a high-speed ion conduction channel network, thereby improving the kinetic performance of the lithium metal battery cell.

[0123] In the embodiments of this application, the positive electrode active material film layer includes a plasticizer, which is used to dissociate and / or disperse lithium salt. Due to the presence of the plasticizer, the oxidation stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell is improved, thereby improving the cycle life of the lithium metal battery cell.

[0124] Before use, the plasticizer of a lithium metal battery cell needs to be activated or heated to transform it into a gel and / or liquid state. This treatment can be performed at the positive electrode layer or at the lithium metal battery cell layer.

[0125] In some optional embodiments, the plasticizer is in a gel and / or liquid state in the positive electrode active material film layer.

[0126] In some optional embodiments, the plasticizer content is 0.5% to 10% by mass, based on the total mass of the positive electrode active material film. Therefore, an appropriate amount of plasticizer promotes the dissociation of lithium ions in the lithium salt, forming locally high-concentration lithium-ion regions in situ, constructing high-speed ion conduction channels, and improving the ionic conductivity of the positive electrode active material film. An appropriate amount of plasticizer can achieve a balance between battery energy density and the ionic conductivity of the positive electrode active material film.

[0127] Optionally, based on the total mass of the positive electrode active material film, the mass content of the plasticizer can be any value or a range of combinations thereof from 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, and 10.0%.

[0128] In some optional embodiments, the plasticizer content is 2% to 5% by mass, based on the total mass of the positive electrode active material film. This further improves the ionic conductivity of the positive electrode active material film and enhances the kinetic performance of the lithium metal battery cell. The presence of the plasticizer also improves the oxidative stability between the positive electrode active material film and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell.

[0129] In some alternative embodiments, the plasticizer includes one or more of cyano, sulfur-oxygen double bond, and carbonyl.

[0130] In this embodiment, cyano (C≡N bond), sulfur-oxygen double bond (S=O bond), and carbonyl (C=O) groups have high electron density and / or negative charge (lone pair electrons), which can effectively solubilize lithium ions and stably dissociate them, thus promoting the dissociation of lithium salts. Alternatively, they can effectively reduce the lattice energy of lithium salts, making them easier to dissociate and increasing the degree of dissociation. This comprehensively improves the mobility of lithium ions and the kinetic performance of the battery.

[0131] Generally, plasticizers are solid at room temperature, typically at 25 degrees Celsius or less. This solid plasticizer allows for more uniform dispersion within the positive electrode active material film, improving the oxidation stability between the positive electrode active material film and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell. In some optional embodiments, the plasticizer includes one or more of the following: dimethyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, sulfonamide, methanesulfonamide, ethylsulfonamide, propylsulfonamide, benzylsulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexylsulfonamide, fluorophenyl sulfone, ethylmethyl sulfone, 3-cyanopyridine, 2-cyanophenylacetonitrile, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0132] The components and their contents in the positive electrode active material film layer of the positive electrode sheet can be determined according to conventional methods in the field. For example, gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), inductively coupled plasma optical emission spectrometry (ICP-OES), infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance, and other methods can be used for detection.

[0133] For example, infrared spectroscopy can be used to identify compounds contained in the film layer of positive electrode active materials, such as the characteristic peak of the sulfur-oxygen double bond in diethyl sulfone at 1060 cm⁻¹. -1 -1040cm -1 Within the specified range, high-resolution gas chromatography-high-resolution mass spectrometry (HPLC-MS / MS) can be used to separate different components in the positive electrode active material film and obtain high-precision molecular weights, thereby determining the atomic composition; then, the specific molecular structure of each component can be confirmed by nuclear magnetic resonance (NMR) spectroscopy results.

[0134] In some optional embodiments, the plasticizer is a solid particle with an average volume particle size Dv50 of 0.1 μm to 3 μm.

[0135] Optionally, the average volumetric particle size Dv50 of the plasticizer can be any value or a range of combinations thereof from 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, and 3.0 μm.

[0136] In this embodiment, the plasticizer in the lithium metal battery cell is in solid particulate form before activation. The solid particulate plasticizer can be more uniformly dispersed in the positive electrode active material film, further improving the ionic conductivity of the positive electrode active material film and enhancing the kinetic performance of the lithium metal battery cell. The presence of the plasticizer further improves the oxidative stability between the positive electrode active material film and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell.

[0137] In some optional embodiments, the plasticizer is uniformly dispersed in the positive electrode active material film layer.

[0138] In this embodiment, the plasticizer is uniformly dispersed in the positive electrode active material film layer, further improving the ionic conductivity of the positive electrode active material film layer and enhancing the kinetic performance of the lithium metal battery cell. The presence of the plasticizer further improves the oxidative stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell, thereby increasing the cycle life of the lithium metal battery cell.

[0139] Figure 5 shows a schematic diagram of a positive electrode sheet in an embodiment of this application. As shown in Figure 5, the positive electrode sheet 520 includes a positive current collector 521 and a positive active material film layer 522. The dots in the positive active material film layer 522 are uniformly dispersed plasticizers.

[0140] In some optional embodiments, the positive electrode active material film layer includes a porous material, which includes one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

[0141] Porous organic frameworks (COFs) and porous metal-organic frameworks (MOFs) are both materials with highly ordered porous structures. The pore network of COFs is linked by strong covalent bonds and typically does not contain metal components. Porous metal-organic frameworks are three-dimensional network structures formed by coordination bonds between metal ions or metal clusters and organic ligands. Aerogels include, but are not limited to, silica aerogels, titanium dioxide aerogels, zirconium dioxide aerogels, alumina aerogels, magnesium oxide aerogels, vanadium oxide aerogels, boron nitride aerogels, or titanium nitride aerogels. Molecular sieves include, but are not limited to, at least one of microporous silica-alumina molecular sieves, mesoporous silica-alumina molecular sieves, or macroporous silica-alumina molecular sieves.

[0142] Porous metal-organic framework materials can include ZIF-8(C8H) 12 N4·Zn), ZIF-67(C8H) 12 N4·Co), MIL-100(C9H6O6·Fe), MIL-101(C 24 H 16 Cr3FO15 One or more of MOF-5.

[0143] MOF-5, i.e., (Zn4O(C8H6O4)3×(HCON(CH3)2)8(C6H5Cl)), can be understood as follows: Zn4O represents a metal cluster formed by zinc (Zn) ions and oxygen (O). (C8H6O4)3 is terephthalic acid (TPA), which is the organic ligand in this framework structure. (HCON(CH3)2)8 is a molecule of dimethylformamide (DMF), which is usually the solvent used in MOF synthesis. (C6H5Cl) is chlorobenzene, which may also be a component in the synthesis process.

[0144] The active sites on the surface of porous materials promote the dissociation of lithium salts, further facilitating the interaction between plasticizers and lithium salt cations, thus comprehensively constructing high-speed ion conduction channels and improving the ionic conductivity of the positive electrode active material film. For example, amino (-NH2), carboxyl (-COOH), or sulfonic acid (-SO3H) groups on the surface of porous materials can promote the dissociation of lithium ions by forming hydrogen bonds or through acid-base interactions. Metal / non-metal ions (such as zinc, copper, aluminum, silicon, etc.) in MOFs, aerogels, and molecular sieves have different oxidation states and coordination environments. These unsaturated metal sites can interact with lithium salt anions, thereby promoting the dissociation of lithium ions and enhancing their migration ability.

[0145] In the embodiments of this application, the porous characteristics of the porous material can accommodate the activated plasticizer, restrict the flow of the plasticizer, and make at least part of the surface of the porous material in a gel state, which comprehensively improves the stability of the positive electrode active material film and improves the cycle life of the lithium metal battery cell; the plasticizer and dissociated lithium ions in the pores of the porous material also form a high-concentration lithium ion region, constructing a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0146] In some optional embodiments, the mass content of the porous material is 0.5% to 3% based on the total mass of the positive electrode active material film. The mass content of the porous material can be any value or range of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%.

[0147] Within the aforementioned mass content range, the porous material can improve the structural stability and porosity of the positive electrode active material film. The active sites on the porous material surface promote the dissociation of lithium salts, increasing the ionic conductivity of the positive electrode active material film. Furthermore, the plasticizers and dissociated lithium ions within the pores of the porous material also create high-concentration lithium-ion regions, constructing high-speed ion conduction channels and further enhancing the kinetic performance of lithium metal battery cells.

[0148] In some optional embodiments, the average pore size of the porous material is 0.3 nm to 50 nm. Optionally, the average pore size of the porous material can be any value or a range of combinations thereof from 0.3 nm, 0.5 nm, 1.0 nm, 1.5 nm, 2.0 nm, 2.5 nm, 3.0 nm, 3.5 nm, 4.0 nm, 4.5 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, and 50 nm.

[0149] The average pore size of the porous material is within the above range, which can effectively bind the activated liquid plasticizer. The plasticizer and dissociated lithium ions in the pores also form a high-concentration lithium ion region, creating a high-speed ion conduction channel and further improving the dynamic performance of lithium metal battery cells.

[0150] In some optional embodiments, the porosity of the porous material is 80% to 99.8%.

[0151] The porosity of porous materials can be 80.0%, 80.5%, 81.0%, 81.5%, 82.0%, 82.5%, 83.0%, 83.5%, 84.0%, 84.5%, 85.0%, 85.5%, 86.0%, 86.5%, 87.0%, 87.5%, 88.0%, 88.5%, 89.0%, 89.5%, and 90.0%. The percentages are any values ​​or ranges of the following: 90.5%, 91.0%, 91.5%, 92.0%, 92.5%, 93.0%, 93.5%, 94.0%, 94.5%, 95.0%, 95.5%, 96.0%, 96.5%, 97.0%, 97.5%, 98.0%, 98.5%, 99.0%, 99.5%, and 99.8%. Therefore, porous materials can accommodate the activated liquid plasticizer and lithium ions, which is beneficial for constructing lithium-ion conduction pathways and further improving the kinetic performance of lithium metal battery cells.

[0152] In some optional embodiments, the porous material is in particulate form, and the volume average particle size Dv50 of the porous material is 1 μm to 6 μm.

[0153] Optionally, the volume average particle size Dv50 of the porous material can be any value or a range thereof from 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, and 6.0 μm. Therefore, a volume average particle size Dv50 within the above range allows the porous material to be uniformly dispersed in the positive electrode active material film, promoting lithium salt dissociation, improving the stability of the positive electrode active material film, and increasing the cycle life of the lithium metal battery cell.

[0154] The volume average particle size D of porous materials v The value of 50 is known in the art and represents the particle size corresponding to a cumulative volume distribution percentage of 50%, which can be determined using instruments and methods known in the art. For example, it can be conveniently determined using a laser particle size analyzer, such as the Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK, according to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0155] In some alternative embodiments, the lithium-conducting binder includes one or more of polyacrylonitrile and polycaprolactone.

[0156] Compared to polyvinylidene fluoride (PVDF), which is mainly used as a binder in batteries, PVDF does not have groups that can interact with lithium ions and anions of lithium salts and cannot participate in the dissociation of lithium salts. Therefore, it cannot promote the conduction of lithium ions in the positive electrode active layer.

[0157] Lithium-conducting binders also possess high electron density and / or negatively charged (lone pair) groups, such as cyano (C≡N bond) and / or carbonyl (C=O), which can participate in the dissociation of lithium salts and provide conduction channels for lithium ions to jump along the aforementioned group sites. Furthermore, lithium-conducting binders, lithium salts, and plasticizers together construct a high-concentration lithium-ion region, building a high-speed ion conduction channel and further improving the kinetic performance of lithium metal battery cells. Lithium-conducting binders can improve the interfacial stability between the electrode and the electrolyte, reducing electrode surface instability and electrolyte decomposition problems. Thanks to the good oxidation resistance of lithium-conducting binders, they can improve the cycle life and interfacial stability of lithium metal battery cells.

[0158] In some optional embodiments, the weight-average molecular weight of polyacrylonitrile is 50,000 to 500,000.

[0159] Optionally, the weight average molecular weight of polyacrylonitrile can be any value or a range of combinations thereof from 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, and 500,000.

[0160] The weight-average molecular weight of polyacrylonitrile is within the above range, which results in a network of appropriate size in the polymer. This facilitates the dissociation of lithium salts and provides a conduction channel for lithium ions to jump along the above-mentioned group sites, thereby further improving the kinetic performance of lithium metal battery cells.

[0161] In some optional embodiments, the weight-average molecular weight of polycaprolactone is from 10,000 to 100,000.

[0162] Optionally, the weight-average molecular weight of polycaprolactone can be any value or a range thereof from 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, and 100,000. Therefore, a weight-average molecular weight of polycaprolactone within the above range allows for a suitable network size in the polymer, which is beneficial for participating in the dissociation of lithium salts and provides a pathway for lithium ions to conduct along the aforementioned group sites or network pores, further improving the kinetic performance of lithium metal battery cells.

[0163] The weight-average molecular weight of polymers such as polyacrylonitrile and polycaprolactone has a well-known meaning in the art and can be determined using instruments and methods known in the art. For example, high-temperature gel permeation chromatography (GPC) can be used. The test can be performed using a gel permeation chromatography (GPC) instrument, such as the Polymer Char GPC-IR high-temperature gel permeation chromatograph. The test can be referenced to the international standard ISO 16014-1-2019.

[0164] In some optional embodiments, the mass content of the lithium-conducting binder is 1% to 10% based on the total mass of the positive electrode active material film.

[0165] Optionally, based on the total mass of the positive electrode active material film, the mass content of the lithium-conducting binder can be any value or a range thereof from 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, and 10.0%. A mass content of lithium-conducting binder within the above range can further improve the kinetic performance of the lithium metal battery cell; the lithium-conducting binder can improve the interfacial stability between the electrode and the electrolyte, thereby increasing the cycle life and stability of the lithium metal battery cell.

[0166] In some optional embodiments, the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0167] In some optional embodiments, the mass content of lithium salt is 1% to 10% based on the total mass of the positive electrode active material film.

[0168] Optionally, based on the total mass of the positive electrode active material film, the mass content of the lithium salt can be any value or a range of combinations thereof from 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, and 10.0%.

[0169] In some optional embodiments, the ionic conductivity of the positive electrode is 1×10⁻⁶. -4 S / cm to 1S / cm.

[0170] Optionally, the ionic conductivity of the positive electrode can be 1×10⁻⁶. -4 S / cm, 1.2×10 -4 S / cm, 1.5×10 -4 S / cm, 1.8×10 -4 S / cm, 2×10 -4 S / cm, 2.5×10 -4 S / cm, 3×10 -4 S / cm, 4×10 -4 S / cm, 5×10 -4 S / cm, 6×10 - 4 S / cm, 7×10 -4 S / cm, 8×10 -4S / cm, 9×10 -4 S / cm, 1×10 -3 S / cm, 2×10 -3 S / cm, 3×10 -3 S / cm, 4×10 -3 S / cm, 5×10 -3 S / cm, 6×10 -3 S / cm, 7×10 -3 S / cm, 8×10 -3 S / cm, 9×10 -3 S / cm, 1×10 -2 S / cm, 2×10 -2 S / cm, 3×10 -2 S / cm, 4×10 -2 S / cm, 5×10 -2 S / cm, 6×10 -2 S / cm, 7×10 -2 Any value or a range thereof from S / cm, 0.1S / cm, 0.5S / cm, 0.8S / cm, and 1S / cm. A positive electrode with an ionic conductivity within this range can improve the kinetic performance of a single lithium-ion battery cell.

[0171] In some optional embodiments, the positive electrode active material film layer comprises 80% to 96% positive electrode active material, which includes one or more of lithium-containing transition metal oxides and lithium-containing transition metal phosphates.

[0172] Examples of lithium transition metal oxides may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium transition metal phosphate cathode active materials may include one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds. This application is not limited to these materials, and other conventionally known materials that can be used as cathode active materials may also be used.

[0173] For example, lithium-containing transition metal oxides may include ternary materials, quaternary materials, etc., and lithium-containing transition metal oxides have relatively high energy density and reversible capacity.

[0174] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0175] Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides, such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0176] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, the molar oxygen (O) content in the examples of positive electrode active materials in this disclosure is only a theoretical value. Lattice oxygen release causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0177] In some optional embodiments, the positive electrode active material film layer includes a conductive agent, which includes long-range conductive carbon and short-range conductive carbon.

[0178] Long-range conductive carbon usually refers to carbon materials that have high conductivity and can form a continuous conductive network in electrode materials, such as carbon fibers and carbon nanotubes.

[0179] In this embodiment, long-range conductive carbon provides a long-distance electron conduction path and forms a continuous conductive network, improving the overall conductivity of the electrode. Long-range conductive carbon also provides structural support, mitigating the cracking or pulverization of electrode materials due to volume changes during battery charging and discharging, reducing material loss and capacity decay, and improving the cycle life of lithium metal battery cells. Short-range conductive carbon typically refers to carbon materials with good conductivity but unable to form a long-distance conductive network, such as carbon black and acetylene black.

[0180] The combined use of long-range and short-range conductive carbon can provide an overall conductive network, improve the conductivity and mechanical strength of the positive electrode, and thus improve the resistance of the positive electrode. Electronic resistance affects charge and discharge polarization, which in turn affects the rate performance of lithium metal battery cells.

[0181] In some optional embodiments, the mass content of the conductive agent is 0.5% to 3% based on the total mass of the positive electrode active material film.

[0182] Optionally, based on the total mass of the positive electrode active material film, the mass content of the conductive agent can be any value or range of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%.

[0183] In some optional embodiments, the mass ratio of long-range conductive carbon to short-range conductive carbon is 1:(0.5 to 5). Optionally, the mass ratio of long-range conductive carbon to short-range conductive carbon can be any ratio or a range thereof from 1:0.5, 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5, 1:4.0, 1:4.5, 1:5.0.

[0184] In this embodiment, the mass ratio of long-range conductive carbon to short-range conductive carbon is within the above range, which constructs a good conductive network, improves the conductivity and mechanical strength of the positive electrode sheet, fills micropores, improves local conductivity, increases reactivity, improves material uniformity, and comprehensively improves the energy density, cycle life and kinetic performance of lithium metal battery cells.

[0185] In some alternative embodiments, the long-range conductive carbon includes one or more of vapor-grown carbon fibers and carbon nanotubes.

[0186] In some alternative embodiments, the short-range conductive carbon includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, and carbon dots.

[0187] In some alternative embodiments, the positive electrode may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0188] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0189] As an example, the positive current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0190] Secondly, embodiments of this application provide a method for preparing a positive electrode sheet for a lithium metal battery cell, comprising:

[0191] A positive electrode active material slurry is coated on a positive electrode current collector to obtain an initial positive electrode sheet. The positive electrode active material slurry includes a plasticizer, a lithium-conducting binder, and a lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

[0192] The initial positive electrode sheet is heated to transform the plasticizer into a gel phase and / or liquid state to obtain the positive electrode sheet.

[0193] In the preparation method of this application embodiment, when the plasticizer is in the gel phase and / or liquid phase, the electron-rich functional groups of the plasticizer and the cations of the lithium salt interact, promoting the dissociation of the lithium salt and forming a region with a local high concentration of lithium ions in situ, thus constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film layer; furthermore, the lithium-conducting binder, lithium salt and plasticizer included in the positive electrode active material film layer construct a high-concentration lithium ion region, construct a high-speed ion conduction channel, and improve the kinetic performance of the lithium metal battery cell.

[0194] In the embodiments of this application, the positive electrode active material film layer includes a plasticizer, which is used to dissociate and / or disperse lithium salt. Due to the presence of the plasticizer, the oxidation stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell is improved, the interfacial side reactions between the positive electrode sheet and the electrolyte are suppressed, and the cycle life of the lithium metal battery cell is improved.

[0195] In some optional embodiments, the plasticizer is one or more of the following: dimethyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, methanesulfonamide, sulfonamide, ethyl sulfonamide, propyl sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, fluorophenyl sulfone, ethyl methyl sulfone, 3-cyanopyridine, 2-cyanophenylacetonitrile, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0196] In some optional embodiments, the plasticizer is a solid particle with an average volume particle size Dv50 of 0.1 μm to 3 μm.

[0197] Optionally, the average volumetric particle size Dv50 of the plasticizer can be any value or a range of combinations thereof from 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, and 3.0 μm.

[0198] Dv50 represents the particle size corresponding to a cumulative volumetric distribution percentage of 50% for the material. It can be measured using a laser particle size analyzer, referring to GB / T19077-2016. During testing, add 1g of the sample to a clean small beaker, along with 20ml of deionized water. Sonicate at 53kHz / 120W for 5 minutes to ensure complete dispersion. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the sonicated solution to ensure uniform dispersion, then place it in the sample cell as required and begin measuring the particle size. A MasterSizer 3000 laser particle size analyzer can be used as the testing instrument.

[0199] In some optional embodiments, the melting point T of the plasticizer satisfies: 25°C ≤ T ≤ 120°C, and the heating temperature is greater than the melting point of the plasticizer.

[0200] Optionally, the melting point T of the plasticizer can be any value or a range of combinations thereof from 25℃, 30℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, and 120℃.

[0201] In the embodiments of this application, the melting point T of the plasticizer is within the above range, which enables it to be a solid plasticizer at room temperature. However, after heat treatment at a certain temperature, it can be melted into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ. This constructs a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and enhances the dynamic performance of the battery.

[0202] In some alternative embodiments, the plasticizer includes one or more of dimethyl sulfone, diethyl sulfone, methanesulfonamide, and cyanophenylacetonitrile.

[0203] In some alternative embodiments, the plasticizer includes one or more of dipropyl sulfone, sulfolane, fluorophenyl sulfone, ethyl methanesulfonate, ethyl sulfonamide, propyl sulfonamide, cyanopyridine, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0204] In the embodiments of this application, the solid particulate plasticizer can be solid at room temperature, but after heat treatment at a certain temperature, it can melt into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ, constructing a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and improves the dynamic performance of the battery.

[0205] In some alternative embodiments, the positive electrode active material slurry includes a porous material, which includes one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

[0206] Porous organic frameworks (COFs) and porous metal-organic frameworks (MOFs) are both materials with highly ordered porous structures. The pore network of COFs is linked by strong covalent bonds and typically does not contain metal components. Porous metal-organic frameworks are three-dimensional network structures formed by coordination bonds between metal ions or metal clusters and organic ligands. Aerogels include, but are not limited to, silica aerogels, titanium dioxide aerogels, zirconium dioxide aerogels, alumina aerogels, magnesium oxide aerogels, vanadium oxide aerogels, boron nitride aerogels, or titanium nitride aerogels. Molecular sieves include, but are not limited to, at least one of microporous silica-alumina molecular sieves, mesoporous silica-alumina molecular sieves, or macroporous silica-alumina molecular sieves.

[0207] Porous metal-organic framework materials can include ZIF-8(C8H) 12 N4·Zn), ZIF-67(C8H) 12 N4·Co), MIL-100(C9H6O6·Fe), MIL-101(C 24 H 16 Cr3FO 15 One or more of MOF-5.

[0208] In the embodiments of this application, high-speed ion conduction channels are combined with solid electrolytes or semi-solid electrolytes to improve battery rate performance.

[0209] [Electrolytes]

[0210] In some embodiments, the battery cell also includes an electrolyte, which generally acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be in a gel state (semi-solid) or a solid state.

[0211] Electrolytes can include electrolyte salts and solvents.

[0212] In some embodiments, 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 dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0213] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0214] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0215] In some optional embodiments, the lithium metal battery cell includes a solid electrolyte, which includes one or more of oxide-based solid electrolytes, sulfide-based solid electrolytes, polyethylene oxide electrolytes, and organic-inorganic composite electrolytes composed of polyethylene oxide and inorganic substances.

[0216] For example, oxide-based solid electrolytes can be lithium lanthanum zirconium oxide and its derivatives; sulfide-based solid electrolytes can be Li3PS4 and its derivatives; and polyoxyethylene electrolytes can be polyoxyethylene / lithium bis(trifluoromethanesulfonyl)imide composite electrolytes.

[0217] In this embodiment, the solid electrolyte typically possesses high mechanical strength, which can effectively suppress the growth of lithium dendrites and reduce the risk of battery short circuits. The solid component reduces direct contact between the electrolyte and lithium metal, minimizing adverse reactions between them, improving the interfacial compatibility and stability between the electrolyte and electrode materials, and enhancing the battery's cycle stability. Furthermore, the solid electrolyte exhibits good ionic conductivity, improving the kinetic performance of the lithium metal battery cell.

[0218] In some optional embodiments, the lithium metal battery cell includes a semi-solid electrolyte; the semi-solid electrolyte includes one or more of the following: polyvinylidene fluoride-hexafluoropropylene copolymer gel electrolyte, polyvinylidene fluoride (PVDF) containing liquid organic solvent, polyethylene oxide (PEO) containing liquid organic solvent, polyacrylonitrile (PAN) containing liquid organic solvent, polymethyl methacrylate (PMMA) based gel electrolyte; and covalent organic framework based gel electrolyte containing ionic liquid electrolyte.

[0219] In this embodiment, the liquid organic solvent can be one or more of sulfone, carbonate, nitrile, and ionic liquid.

[0220] In this embodiment, the semi-solid electrolyte can improve the interfacial compatibility and stability between the electrolyte and electrode materials, improve the cycle stability of the battery, improve the ionic conductivity of the lithium metal battery cell, and improve the kinetic performance of the lithium metal battery cell.

[0221] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0222] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0223] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0224] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium-germanium-phosphorus-sulfur, sulfosilium-germanium), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0225] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0226] [Negative electrode plate]

[0227] In some alternative embodiments, the negative electrode current collector includes one or more of elemental lithium and lithium alloys.

[0228] In some optional embodiments, the negative electrode sheet may include a negative current collector and a first metal layer disposed on at least one surface of the negative current collector, wherein the metal element in the first metal layer may include one or more of alkali metal elements and alkaline earth metal elements.

[0229] In some alternative embodiments, the metal material in the first metal layer may include one or more of elemental lithium and lithium alloys.

[0230] Lithium alloys can be alloys formed from metallic lithium with other metallic or non-metallic elements. For example, other metallic elements in lithium alloys may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements may include one or more of boron, carbon, and silicon.

[0231] In some optional embodiments, the negative electrode current collector may include a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, aluminum mesh, copper foam, nickel foam, and aluminum foam. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0232] [Preparation methods for lithium metal battery cells]

[0233] This application provides a method for preparing a lithium metal battery cell, including:

[0234] An initial positive electrode sheet is provided, which includes a positive current collector and an initial positive active material film layer. The initial positive active material film layer includes a plasticizer, a lithium-conducting binder, and a lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

[0235] The initial positive electrode sheet is assembled with the lithium metal negative electrode sheet and the electrolyte to obtain the initial lithium metal battery cell.

[0236] The initial lithium metal battery cell is heated to transform the plasticizer into a gel phase and / or liquid phase to obtain the lithium metal battery cell.

[0237] In the preparation method of this application embodiment, when the plasticizer is in the gel phase and / or liquid phase, the electron-rich functional groups of the plasticizer and the cations of the lithium salt interact, promoting the dissociation of the lithium salt and forming a region with a local high concentration of lithium ions in situ, thus constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film layer; furthermore, the lithium-conducting binder, lithium salt and plasticizer included in the positive electrode active material film layer construct a high-concentration lithium ion region, construct a high-speed ion conduction channel, and improve the kinetic performance of the lithium metal battery cell.

[0238] In the embodiments of this application, the positive electrode active material film layer includes a plasticizer, which is used to dissociate and / or disperse lithium salt. Due to the presence of the plasticizer, the oxidation stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell is improved, thereby improving the cycle life of the lithium metal battery cell.

[0239] In some optional embodiments, the melting point T of the plasticizer satisfies: 25℃≤T≤60℃.

[0240] In the embodiments of this application, the plasticizer has a low melting point and can be a solid plasticizer at room temperature. However, after heat treatment at a certain temperature, it can melt into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ. This constructs a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and enhances the dynamic performance of the battery.

[0241] In some alternative embodiments, the plasticizer includes one or more of dipropyl sulfone, sulfolane, fluorophenyl sulfone, ethyl methanesulfonate, ethyl sulfonamide, propyl sulfonamide, cyanopyridine, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

[0242] In some optional embodiments, the plasticizer is a solid particle with an average volume particle size Dv50 of 0.1 μm to 3 μm.

[0243] In the embodiments of this application, the solid particulate plasticizer can be solid at room temperature, but after heat treatment at a certain temperature, it can melt into a liquid state. At the same time, the electron-rich functional groups of its molecules interact with the cations of lithium salt, promoting the dissociation of lithium salt and forming a local high-concentration lithium ion region in situ, constructing a high-speed ion conduction channel, which significantly improves the lithium ion conductivity in the positive electrode active material film layer and improves the dynamic performance of the battery.

[0244] In some alternative embodiments, the initial positive electrode active material film layer comprises a porous material, including one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

[0245] Porous organic frameworks (COFs) and porous metal-organic frameworks (MOFs) are both materials with highly ordered porous structures. The pore network of COFs is linked by strong covalent bonds and typically does not contain metal components. Porous metal-organic frameworks are three-dimensional network structures formed by coordination bonds between metal ions or metal clusters and organic ligands. Aerogels include, but are not limited to, silica aerogels, titanium dioxide aerogels, zirconium dioxide aerogels, alumina aerogels, magnesium oxide aerogels, vanadium oxide aerogels, boron nitride aerogels, or titanium nitride aerogels. Molecular sieves include, but are not limited to, at least one of microporous silica-alumina molecular sieves, mesoporous silica-alumina molecular sieves, or macroporous silica-alumina molecular sieves.

[0246] Porous metal-organic framework materials can include ZIF-8(C8H) 12 N4·Zn), ZIF-67(C8H) 12 N4·Co), MIL-100(C9H6O6·Fe), MIL-101(C 24 H 16 Cr3FO 15 One or more of MOF-5.

[0247] The preparation methods of lithium metal battery cells are well known. In some optional embodiments, a positive electrode, a lithium metal negative electrode, and an electrolyte can be assembled to form a lithium metal battery cell. As an example, the positive electrode, electrolyte membrane, and lithium metal negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is then placed in an outer package and subjected to vacuum sealing, settling, formation, and shaping processes to obtain a lithium metal battery cell. Multiple lithium metal battery cells can further be connected in series, parallel, or a combination thereof to form a lithium metal battery cell module. Multiple lithium metal battery cell modules can also be connected in series, parallel, or a combination thereof to form a lithium metal battery cell pack. In some optional embodiments, multiple lithium metal battery cells can also be directly assembled into a lithium metal battery cell pack.

[0248] Electrical appliances

[0249] This application provides an electrical device, including the battery device of any of the above embodiments.

[0250] Lithium metal battery cells can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0251] Electrical devices can be selected from lithium metal battery cells, lithium metal battery cell modules, or lithium metal battery cell packs according to their usage requirements.

[0252] Figure 6 is a schematic diagram of an example electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this device, lithium metal battery packs or lithium metal battery modules can be used.

[0253] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can utilize lithium metal battery cells as their power source.

[0254] Example

[0255] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0256] Example 1

[0257] Preparation of lithium metal battery cells:

[0258] Preparation of positive electrode sheet: Lithium iron phosphate (LiFePO4), conductive agent acetylene black, binder polyacrylonitrile (weight average molecular weight of 150,000), lithium salt bis(fluorosulfonyl)imide, and plasticizer dimethyl sulfone are mixed in a mass ratio of 92:2:2:2:2. N-methylpyrrolidone solvent is added and stirred until the system is homogeneous to obtain a positive electrode slurry. The solid content of the slurry is 75%. The positive electrode slurry is uniformly coated on both sides of the positive electrode current collector aluminum foil and dried at room temperature to obtain the initial positive electrode sheet. The initial positive electrode sheet is transferred to an oven for further drying. The initial positive electrode sheet is heat-treated at 120°C to activate the plasticizer and convert it into a liquid or gel phase. Then the positive electrode sheet is dried and cut into rectangles to obtain the positive electrode sheet.

[0259] Negative electrode: A lithium metal sheet (lithium metal element) with a thickness of 60μm;

[0260] Electrolyte: 30-micron PEO / LTFSI composite electrolyte membrane, wherein the mass ratio of polyethylene oxide (PEO):LiTFSI:lithium lanthanum zirconium oxide is 6:2:2;

[0261] Separating membrane: None; the electrolyte described above provides this separation function.

[0262] Lithium metal battery cell assembly: The positive electrode, electrolyte and negative electrode are assembled and packaged, and hot-pressed at 60℃ and 2000Pa for 10min to improve the interface contact, thus obtaining a lithium metal battery cell.

[0263] Example 2

[0264] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of sulfolane, and the heat treatment temperature is changed to 60°C.

[0265] Example 3

[0266] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of diethyl sulfone, and the heat treatment temperature is changed to 80°C.

[0267] Example 4

[0268] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of methanesulfonamide, and the heat treatment temperature is changed to 90°C.

[0269] Example 5

[0270] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of ethyl sulfonamide, and the heat treatment temperature is changed to 65°C.

[0271] Example 6

[0272] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of fluorophenyl sulfone, and the heat treatment temperature is changed to 60°C.

[0273] Example 7

[0274] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of 3-cyanopyridine, and the heat treatment temperature is changed to 60°C.

[0275] Example 8

[0276] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of 2-cyanophenylacetonitrile, and the heat treatment temperature is changed to 80°C.

[0277] Example 9

[0278] The preparation method is similar to that in Example 1, except that the plasticizer dimethyl sulfone in the positive electrode active material film layer is replaced with an equal mass of p-fluorobenzonitrile, and the heat treatment temperature is changed to 60°C.

[0279] Example 10

[0280] The preparation method is similar to that of Example 9, except that the content of the plasticizer dimethyl sulfone in the positive electrode sheet is different. The mass content of dimethyl sulfone in the positive electrode active material film layer is 5%. During the preparation of the positive electrode sheet: lithium iron phosphate positive electrode active material, acetylene black conductive agent, polyacrylonitrile binder (weight average molecular weight of 150,000), lithium bis(fluorosulfonyl)imide lithium salt, and p-fluorobenzonitrile plasticizer are mixed in a mass ratio of 89:2:2:2:5.

[0281] Example 11

[0282] The preparation method is similar to that of Example 9, except that the content of the plasticizer dimethyl sulfone in the positive electrode sheet is different. The mass content of dimethyl sulfone in the positive electrode active material film layer is 0.5%. During the preparation of the positive electrode sheet: the positive electrode active material lithium iron phosphate, the conductive agent acetylene black, the binder polyacrylonitrile (weight average molecular weight of 150,000), the lithium salt lithium bis(fluorosulfonyl)imide, and the plasticizer p-fluorobenzonitrile are mixed in a mass ratio of 93.5:2:2:2:0.5.

[0283] Example 12

[0284] The preparation method is similar to that of Example 9, except that the content of the plasticizer dimethyl sulfone in the positive electrode sheet is different. The mass content of dimethyl sulfone in the positive electrode active material film layer is 10%. During the preparation of the positive electrode sheet: the positive electrode active material lithium iron phosphate, the conductive agent acetylene black, the binder polyacrylonitrile (weight average molecular weight of 150,000), the lithium salt lithium bis(fluorosulfonyl)imide, and the plasticizer p-fluorobenzonitrile are mixed in a mass ratio of 84:2:2:2:10.

[0285] Example 13

[0286] The preparation method is similar to that in Example 10, except that the content of lithium salt in the positive electrode is different. When preparing the positive electrode, the positive active material lithium iron phosphate, the conductive agent acetylene black, the binder polyacrylonitrile (weight average molecular weight of 150,000), the lithium salt lithium bisfluorosulfonylimide, and the plasticizer p-fluorobenzonitrile are mixed in a mass ratio of 87:2:2:4:5.

[0287] Example 14

[0288] The preparation method is similar to that in Example 10, except that the content of the lithium-conducting binder in the positive electrode sheet is different. When preparing the positive electrode sheet, the positive active material lithium iron phosphate, the conductive agent acetylene black, the binder polyacrylonitrile (weight average molecular weight of 150,000), the lithium salt lithium bisfluorosulfonylimide, and the plasticizer dimethyl sulfone are mixed in a mass ratio of 87:2:4:2:5.

[0289] Example 15

[0290] The preparation method is similar to that in Example 1, except that the binder in the positive electrode sheet is replaced with polycaprolactone.

[0291] Example 16

[0292] The preparation method is similar to that in Example 1, except that the types and mass ratios of raw materials for the positive electrode active material film are different. Lithium iron phosphate (positive electrode active material), acetylene black (conductive agent), polyacrylonitrile (weight-average molecular weight 150,000) (binder), lithium bis(fluorosulfonyl)imide (lithium salt), dimethyl sulfone (plasticizer), and porous material are mixed in a mass ratio of 91:2:2:2:2:1 to obtain the initial positive electrode sheet. The porous material is COFs (polybenzimidazole), where the structural unit is a benzimidazole group. The average pore size of the porous material is 5 nm; the porosity is >85%; and the volume average particle size (Dv50) is 4 μm.

[0293] Example 17

[0294] The preparation method is similar to that in Example 1, except that the types and mass ratios of raw materials for the positive electrode active material film are different. Lithium iron phosphate (PFP), acetylene black (conductive agent), polyacrylonitrile (weight-average molecular weight 150,000) (binder), lithium bis(fluorosulfonyl)imide (lithium salt), dimethyl sulfone (DMSF) (plasticizer), and porous material are mixed in a mass ratio of 91:2:2:2:2:1 to obtain the initial positive electrode sheet. The porous material is ZIF-8, with an average pore size of 10 nm, a porosity >85%, and a volume average particle size (Dv50) of 4 μm.

[0295] Example 18

[0296] The preparation method is similar to that in Example 4, except that the types and mass ratios of raw materials for the positive electrode active material film are different. Lithium iron phosphate (positive electrode active material), acetylene black (conductive agent), polyacrylonitrile (weight-average molecular weight 150,000) (binder), lithium bis(fluorosulfonyl)imide (lithium salt), dimethyl sulfone (plasticizer), and porous material are mixed in a mass ratio of 91:2:2:2:2:1 to obtain the initial positive electrode sheet. The porous material is silica aerogel with an average pore size of 20 nm, a porosity of 85%, and a volume average particle size (Dv50) of 10 μm.

[0297] Example 19

[0298] The preparation method is similar to that of Example 8, except that the types and mass ratios of raw materials for the positive electrode active material film are different. Lithium iron phosphate (positive electrode active material), acetylene black (conductive agent), polyacrylonitrile (weight-average molecular weight 150,000) (binder), lithium bis(fluorosulfonyl)imide (lithium salt), dimethyl sulfone (plasticizer), and porous material are mixed in a mass ratio of 91:2:2:2:2:1 to obtain the initial positive electrode sheet. The porous material is a microporous silica-alumina molecular sieve with an average pore size of 2 nm, a porosity of 85%, and a volume average particle size (Dv50) of 4 μm.

[0299] Comparative Example 1

[0300] The preparation method is similar to that in Example 1, except that no plasticizer is added when preparing the positive electrode sheet; and the binder polyacrylonitrile is replaced with an equal mass of polyvinylidene fluoride.

[0301] Comparative Example 2

[0302] The preparation method is similar to that in Example 1, except that no plasticizer is activated when preparing the positive electrode sheet: when drying the NMP of the positive electrode film, the plasticizer will precipitate in solid form and the plasticizer and lithium salt will separate. Therefore, the initial positive electrode is directly cut into a 40mm*50mm rectangle for use as the positive electrode sheet without activation step, and an unactivated positive electrode sheet is obtained.

[0303] Comparative Example 3

[0304] The preparation method is similar to that in Example 1, except that no plasticizer is added when preparing the positive electrode sheet; and polyacrylonitrile is still used as the binder.

[0305] Comparative Example 4

[0306] The preparation method is similar to that in Example 1, except that when preparing the positive electrode sheet, the binder polyacrylonitrile is replaced with an equal mass of polyvinylidene fluoride.

[0307] Comparative Example 5

[0308] The preparation method is similar to that in Example 11, except that succinic anionyl nitrile is replaced with succinic anionyl nitrile in the preparation of the positive electrode sheet. The mass content of succinic anionyl nitrile in the positive electrode active material film layer is 0.5%.

[0309] Test section

[0310] 1) Positive Electrode Ionic Conductivity Testing: The positive electrode was prepared according to the above examples and comparative examples, with the following differences: other components remained unchanged, but the conductive agent was removed to prevent internal short circuits; the positive electrode slurry was uniformly coated on both sides of the positive current collector aluminum foil, and dried at room temperature to obtain the initial positive electrode; the initial positive electrode was transferred to an oven for further drying, and then heated at 60°C (a temperature higher than the melting point of the corresponding plasticizer) to dry it and obtain the positive electrode. Simultaneously, appropriately sized smooth aluminum foil was cut as the counter electrode, and assembled into an aluminum / aluminum symmetrical battery. An electrochemical workstation was used to test the electrochemical AC impedance spectroscopy to obtain the impedance of the positive electrode active material film. The ionic conductivity of the positive electrode active material film was calculated using the formula: Ionic conductivity = Thickness of one side of the positive electrode active material film / (Area * Impedance value). The electrode area was 20.79 cm². 2 The unit of ionic conductivity is Siemens per centimeter.

[0311] The test results are shown in Table 1.

[0312] Table 1. Test results of the positive electrode sheet.

[0313] As shown in Table 1, the positive electrode sheets of Examples 1-9 contained plasticizers and lithium-conducting binders, while Comparative Examples 1 and 3-5 did not contain at least one of these additives. The positive electrode sheets of Examples 1-9 achieved better ionic conductivity. Compared to Comparative Example 2, the plasticizer in Comparative Example 2 was not activated, while the plasticizer in Example 1 was activated. Therefore, the positive electrode sheet of Example 1 achieved better ionic conductivity.

[0314] Compared to Example 1, Examples 11-15 differ in the type of lithium-conducting binder, the type of electrolyte, the lithium salt content, and the mass content of plasticizer in the positive electrode sheet, which to some extent affects the ionic conductivity of the positive electrode sheet.

[0315] Compared to Example 1, Examples 16-19 incorporate porous materials in the positive electrode, thereby improving the ionic conductivity of the positive electrode.

[0316] 3) Cycle life test of lithium metal battery cells: The ambient temperature for cell cycling was set to 25℃, and charge-discharge cycles were performed using a rate of 0.5C (i.e., 70mA). The cut-off voltages for charge and discharge were set to 4.3V and 2.8V, respectively. The number of cycles completed by the lithium metal battery cell when the discharge capacity decays to 80% of the first discharge capacity is defined as the cycle life of the lithium metal battery cell.

[0317] The test results are shown in Table 2.

[0318] Figure 7 shows the impedance curves of the positive electrode sheets of Embodiment 1 and Comparative Example 2 of this application. Figure 8 shows the impedance curve of the positive electrode sheet of Comparative Example 1 of this application. It is illustrated that the positive electrode sheets of the embodiments contain lithium-conducting additives and plasticizers. After activation of the plasticizers, the impedance of the positive electrode sheets is reduced.

[0319] As shown in Table 1, compared with Comparative Examples 1 and 3-4, Examples 1 to 15 contain lithium-conducting additives and plasticizers in their positive electrode sheets. Activation of the plasticizer improves the cycle life of the lithium battery cells. In Comparative Example 2, the plasticizer was not activated, while in Example 1 it was activated. The lithium battery cells in Example 1 have better cycle life, indicating that activation of the plasticizer is necessary to improve the performance of the lithium battery cells.

[0320] As can be seen from Examples 1 to 15 compared with Comparative Example 5, the addition of plasticizer to the positive electrode sheet of this application improves the cycle life of the lithium battery cell compared with other plasticizers in the prior art.

[0321] Compared with Examples 16 to 19, Examples 1 to 15 show that adding porous materials to the positive electrode further improves the cycle life and ionic conductivity of the battery.

[0322] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A lithium metal battery cell, comprising a lithium metal negative electrode and a lithium metal positive electrode, wherein, The positive electrode includes a positive current collector and a positive active material film layer disposed on at least one side of the positive current collector. The positive active material film layer includes a lithium-conducting binder, a lithium salt, and a plasticizer. The plasticizer is used to dissociate and / or disperse the lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds.

2. The lithium metal battery cell according to claim 1, wherein, Based on the total mass of the positive electrode active material film, the mass content of the plasticizer is 0.5% to 10%.

3. The lithium metal battery cell according to claim 1 or 2, wherein, Based on the total mass of the positive electrode active material film, the mass content of the plasticizer is 2% to 5%.

4. The lithium metal battery cell according to any one of claims 1 to 3, wherein, The plasticizer meets one or more of the following conditions: 1) The plasticizer includes one or more of the following: dimethyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, sulfonamide, methanesulfonamide, ethyl sulfonamide, propyl sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, fluorophenyl sulfone, ethyl methyl sulfone, 3-cyanopyridine, 2-cyanophenylacetonitrile, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile; 2) The plasticizer includes one or more of cyano, sulfur-oxygen double bond, and carbonyl groups; 3) The plasticizer is a solid particle, and the average volume particle size Dv50 of the plasticizer is 0.1 μm to 3 μm; 3) The plasticizer is uniformly dispersed in the positive electrode active material film layer.

5. The lithium metal battery cell according to any one of claims 1 to 4, wherein, The positive electrode active material membrane layer includes a porous material, which includes one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

6. The lithium metal battery cell according to claim 5, wherein, The porous material satisfies one or more of the following conditions: 1) Based on the total mass of the positive electrode active material film, the mass content of the porous material is 0.5% to 3%; 2) The average pore size of the porous material is 0.3 nm to 50 nm; 3) The porosity of the porous material is 80% to 99.8%; 4) The volume average particle size Dv50 of the porous material is 1μm to 6μm.

7. The lithium metal battery cell according to any one of claims 1 to 6, wherein, The positive electrode sheet satisfies one or more of the following conditions: 1) Based on the total mass of the positive electrode active material film, the mass content of the lithium-conducting binder is 0.5% to 10%; 2) The lithium-conducting binder includes one or more of polyacrylonitrile and polycaprolactone; 3) Based on the total mass of the positive electrode active material film, the mass content of the lithium salt is 1% to 10%; 4) The lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate. 5) The ionic conductivity of the positive electrode is 1×10⁻⁶. -4 S / cm to 1S / cm.

8. The lithium metal battery cell according to any one of claims 1 to 7, wherein, The positive electrode active material film layer comprises 80% to 96% positive electrode active material, which includes one or more of lithium-containing transition metal oxides and lithium-containing transition metal phosphates.

9. The lithium metal battery cell according to any one of claims 1 to 8, wherein, The positive electrode active material film layer includes a conductive agent, which includes long-range conductive carbon and short-range conductive carbon.

10. The lithium metal battery cell according to claim 9, wherein, The conductive agent satisfies one or more of the following conditions: 1) Based on the total mass of the positive electrode active material film, the mass content of the conductive agent is 0.5% to 3%; 2) The mass ratio of the long-range conductive carbon to the short-range conductive carbon is 1:(0.5 to 5); 3) The long-range conductive carbon includes one or more of vapor-grown carbon fibers and carbon nanotubes. 4) The short-range conductive carbon includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, and carbon dots.

11. The lithium metal battery cell according to any one of claims 1 to 10, wherein, in, The lithium metal battery cell includes a solid electrolyte, which includes one or more of the following: oxide solid electrolyte, sulfide solid electrolyte, polyoxyethylene electrolyte, and organic-inorganic composite electrolyte composed of polyoxyethylene and inorganic substances.

12. The lithium metal battery cell according to any one of claims 1 to 11, wherein, in, The lithium metal battery cell includes a semi-solid electrolyte; the semi-solid electrolyte includes one or more of the following: polyvinylidene fluoride-hexafluoropropylene copolymer gel electrolyte, polyvinylidene fluoride containing liquid organic solvent, polyethylene oxide containing liquid organic solvent, polyacrylonitrile containing liquid organic solvent, polymethyl methacrylate gel electrolyte containing liquid organic solvent, and covalent organic framework gel electrolyte containing ionic liquid electrolyte.

13. A method for preparing a positive electrode sheet for a lithium metal battery cell, wherein, include: A positive electrode active material slurry is coated on a positive electrode current collector to obtain an initial positive electrode sheet. The positive electrode active material slurry includes a plasticizer, a lithium binder, and a lithium salt. The plasticizer includes one or more of sulfone compounds, sulfonamide compounds, and aromatic nitrile compounds. The initial positive electrode sheet is heated to transform the plasticizer into a gel phase and / or liquid state, thereby obtaining the positive electrode sheet containing a film layer of positive active material.

14. The preparation method according to claim 13, wherein, The plasticizer includes one or more of the following: dimethyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, methyl sulfonamide, sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, fluorophenyl sulfone, ethyl methyl sulfone, 3-cyanopyridine, 2-cyanophenylacetonitrile, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

15. The preparation method according to claim 13 or 14, wherein, The plasticizer meets one or more of the following conditions: 1) The melting point T of the plasticizer satisfies: 25℃<T≤120℃, and the heating temperature is greater than the melting point of the plasticizer; 2) The plasticizer includes one or more of dimethyl sulfone, diethyl sulfone, methanesulfonamide, sulfonamide, benzyl sulfonamide, trifluoromethanesulfonamide, cyclopropanesulfonamide, cyclohexyl sulfonamide, and cyanophenylacetonitrile; 3) The plasticizer is a solid particle, and the average volume particle size Dv50 of the plasticizer is 0.1 μm to 3 μm.

16. A method for preparing a lithium metal battery cell, wherein, include: An initial positive electrode sheet is provided, the initial positive electrode sheet comprising a positive current collector and an initial positive active material film layer, the initial positive active material film layer comprising a plasticizer, a lithium binder and a lithium salt, the plasticizer comprising one or more of sulfone compounds, sulfonamide compounds and aromatic nitrile compounds; The initial positive electrode sheet is assembled with the lithium metal negative electrode sheet and the electrolyte to obtain the initial lithium metal battery cell. The initial lithium metal battery cell is heated to transform the plasticizer into a gel phase and / or liquid phase to obtain the lithium metal battery cell.

17. The preparation method according to claim 16, wherein, The melting point T of the plasticizer satisfies the following condition: 25℃≤T≤60℃.

18. The preparation method according to claim 16 or 17, wherein, The plasticizer includes one or more of dipropyl sulfone, sulfolane, fluorophenyl sulfone, ethyl methanesulfonate, ethyl sulfonamide, propyl sulfonamide, cyanopyridine, p-fluorobenzonitrile, o-bromobenzonitrile, and o-chlorobenzonitrile.

19. The preparation method according to any one of claims 16 to 18, wherein, The plasticizer is a solid particle, and the average volume particle size Dv50 of the plasticizer is 0.1 μm to 3 μm.

20. The preparation method according to any one of claims 13 to 19, wherein, The positive electrode active material membrane layer includes a porous material, which includes one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

21. The preparation method according to claim 20, wherein, The porous material satisfies one or more of the following conditions: 1) Based on the total mass of the positive electrode active material film, the mass content of the porous material is 0.5% to 3%; 2) The average pore size of the porous material is 0.3 nm to 50 nm; 3) The porosity of the porous material is 80% to 99.8%; 4) The volume average particle size Dv50 of the porous material is 1μm to 6μm.

22. A battery device, wherein, It includes lithium metal battery cells according to any one of claims 1 to 12 or lithium metal battery cells prepared by any one of claims 16 to 21.

23. An electrical appliance, wherein, Includes the battery device of claim 22, wherein the power-consuming device is used to store or provide electrical energy.

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