Lithium metal battery monomer and preparation method thereof, preparation method of positive pole piece, battery device and power utilization device

Abstract

The invention provides a lithium metal battery monomer and a preparation method thereof, a preparation method of a positive pole piece, a battery device and a power utilization device. The lithium metal battery monomer comprises a lithium metal negative pole piece, an electrolyte and the positive pole piece, the positive pole piece comprises a positive current collector and a positive active material film layer arranged on at least one side of the positive current collector, and the positive active material film layer comprises a lithium-conducting binder, a lithium salt and a liquid plasticizer; and the film-shaped liquid plasticizer is arranged between the positive electrode active material film layer and the electrolyte. The lithium metal battery cell provided by the embodiment of the invention has improved dynamic performance and cycle life.

Description

Technical Field

[0001] 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

[0002] As batteries are used more widely, people's demands for them are also increasing, such as the growing requirement for higher energy density. Lithium metal battery cells are a promising type of battery. Generally speaking, compared to traditional lithium-ion batteries, lithium metal battery cells offer higher energy density, longer battery life, and greater reliability. With the right electrolyte, they can operate over a wider temperature range.

[0003] Lithium metal battery cells use lithium metal as the negative electrode and employ an electrolyte instead of the traditional liquid electrolyte and separator. This has a certain impact on the dynamic performance of lithium metal battery cells, and therefore needs to be addressed. Summary of the Invention

[0004] 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 liquid plasticizer, constructing a high-concentration lithium-ion region and a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell; it also improves the cycle life of the lithium metal battery cell. Battery devices and power-consuming devices incorporating this lithium metal battery cell have at least the above-mentioned beneficial effects.

[0005] In a first aspect, embodiments of this application provide a lithium metal battery cell, including a lithium metal negative electrode, an electrolyte, 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-conductive binder, a lithium salt, and a liquid plasticizer.

[0006] The liquid plasticizer is present in a membrane form between the positive electrode active material film layer and the electrolyte.

[0007] In this embodiment, the electron-rich functional groups or electron-rich structures of the liquid plasticizer can interact with lithium salt, promoting the dissociation of lithium salt and forming a region with a local high concentration of lithium ions in situ. The liquid plasticizer is distributed in the positive electrode active material film layer, constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film layer. The lithium-conducting binder has a high electron density and / or has negatively charged (lone pair electron) groups, which can participate in the dissociation of lithium salt and provide a conduction channel for lithium ions to jump along the above-mentioned group sites. The lithium-conducting binder and plasticizer included in the positive electrode active material film layer jointly construct a high-speed ion conduction channel network. The liquid plasticizer in a film form between the positive electrode active material film layer and the electrolyte is beneficial to the transport of lithium ions and comprehensively improves the dynamic performance of the lithium metal battery cell.

[0008] In the embodiments of this application, the positive electrode active material film layer includes a liquid plasticizer. Due to the presence of the liquid plasticizer, the liquid plasticizer has oxidation-resistant functional groups, which inhibit the interfacial side reactions between the positive electrode sheet and the electrolyte, improve the stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell, and improve the cycle life of the lithium metal battery cell.

[0009] In this embodiment, at least a portion of the surface of the electrolyte near the positive electrode sheet includes the liquid plasticizer. The liquid plasticizer at this location allows the electrolyte to have better contact with the positive electrode active material film layer, increases the active ion transport path, and improves the kinetic performance of the lithium metal battery cell.

[0010] In some alternative embodiments, the concentration of liquid plasticizer in at least a portion of the positive electrode active material film layer decreases along the direction from the positive electrode current collector.

[0011] In this embodiment, along the direction from the positive electrode active material film to the positive electrode current collector, the concentration of liquid plasticizer in at least a portion of the positive electrode active material film decreases. This facilitates the uniform distribution of a relatively large number of active ions on the surface of the positive electrode active material film within the liquid plasticizer (where the liquid plasticizer content is relatively high). Conversely, a relatively small number of active ions are distributed within the liquid plasticizer near the positive electrode current collector (where the liquid plasticizer content is relatively low). This arrangement fully utilizes the liquid plasticizer, improves the uniform distribution of active ions along the thickness of the positive electrode active material film, increases the cycle life of the lithium metal battery cell, reduces the likelihood of incomplete reaction and lithium plating due to a large number of surface-mounted active ions, and lowers the probability or proportion of dead lithium.

[0012] 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 liquid plasticizer is 0.5% to 10%.

[0013] In some optional embodiments, the liquid plasticizer content is 2% to 5% by mass, based on the total mass of the positive electrode active material film. Therefore, an appropriate proportion 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 liquid plasticizer improves the 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.

[0014] In some optional embodiments, the liquid plasticizer includes one or more of carbonates, phosphate esters, nitrile compounds, and ionic liquids. These liquid plasticizers possess high electron density and / or negative charge (lone pairs of electrons), enabling them to effectively solubilize lithium ions, stably dissociate lithium ions, promote the dissociation of lithium salts, or effectively reduce the lattice energy of lithium salts, making them easier to dissociate and thus improving the overall lithium ion mobility and the kinetic performance of lithium metal battery cells.

[0015] In some optional embodiments, the nitrile compounds include one or more of monocyano nitrile compounds and aromatic nitrile compounds.

[0016] Monocyano compounds typically exhibit high chemical stability, reducing side reactions when in contact with electrolytes and cathode materials, thereby improving the long-term stability of lithium metal battery cells. Monocyano compounds can also reduce interfacial impedance, thus improving the kinetic performance of lithium metal battery cells. In some optional embodiments, the monocyano nitrile compound includes one or more of acetonitrile, propionitrile, and isopropionitrile.

[0017] Aromatic nitrile compounds possess π electrons, exhibiting good electronic conductivity. Aromatic monocyano compounds can enhance interfacial contact with electrode materials through π-π interactions and hydrogen bonding, thereby improving battery conductivity. Aromatic nitrile compounds typically possess good thermal stability, which contributes to improving the structural stability and high-temperature resistance of lithium metal battery cells. In some optional embodiments, the aromatic nitrile compound includes one or more of benzonitrile, o-phthalonitrile, and terephthalonitrile. In some optional embodiments, the nitrile compound is a monocyano aromatic nitrile compound.

[0018] In summary, the specific structure of nitrile compounds can improve the conductivity and thermal stability of the positive electrode, thereby enhancing the cycle life and kinetic performance of lithium metal battery cells.

[0019] In some alternative embodiments, the carbonate includes one or more of dimethyl carbonate, diethyl carbonate, propylene carbonate, and methyl ethyl carbonate.

[0020] Carbonate can be understood as liquid carbonate at room temperature. Liquid carbonate has a wide operating temperature range, can remain liquid at room temperature, and exhibits good stability in high or low temperature environments, improving battery cycle life and reliability. Compared to succinic anhydride, liquid carbonate has a wider operating temperature range and better ionic conductivity.

[0021] In some optional embodiments, the phosphate ester includes one or more of tri(ethyl) phosphate, tri(butyl) phosphate, tri(isooctyl) phosphate, tri(2-ethylhexyl) phosphate, and diisopropyl phosphate.

[0022] Liquid phosphate esters typically offer superior chemical stability, ionic conductivity, interfacial modification effects, and temperature adaptability. Specifically, phosphate esters generally exhibit high chemical stability and low reactivity, demonstrating good resistance to chemical corrosion under battery operating conditions and being less prone to side reactions with electrodes or electrolytes. Phosphate esters are compatible with many electrolyte and electrode materials, forming stable battery structures. Their high ionic conductivity effectively enhances the ionic conductivity of the electrolyte. They help reduce the electrolyte impedance of the battery, thereby increasing the battery's power density and charge / discharge rate.

[0023] In some optional embodiments, the ionic liquid includes one or more of imidazole ionic liquids, ammonium ionic liquids, pyridine ionic liquids, pyrrolidine ionic liquids, piperidine ionic liquids, amino acid ionic liquids, and phosphate ester ionic liquids.

[0024] Ionic liquids are liquids composed of two or more ions that are liquid at or near room temperature, for example, between 20 and 35°C. Ionic liquids typically consist of an organic cation and an inorganic or organic anion.

[0025] Phosphate esters are esterified derivatives of phosphoric acid. Phosphate ester ionic liquids consist of a phosphate ester group combined with a cation and an anion. For example, tributyl phosphate (TnBP) acts as a cation and combines with different anions (such as BF4-, PF6-) to form an ionic liquid. Phosphate esters and phosphate ester ionic liquids are two different types of substances.

[0026] In some alternative embodiments, the liquid plasticizer includes one or more of cyano, sulfur-oxygen double bond, and carbonyl.

[0027] 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 lithium ions, promoting the dissociation of lithium salts, or effectively reducing the lattice energy of lithium salts, making lithium salts easier to dissociate, increasing the degree of dissociation of lithium salts, and comprehensively improving the mobility of lithium ions and the kinetic performance of lithium metal battery cells.

[0028] In some optional embodiments, the positive electrode active material film layer comprises a porous material, which includes one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

[0029] 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.

[0030] 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.

[0031] 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. 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 salts, increasing the ionic conductivity of the positive electrode active material film. The plasticizers and dissociated lithium ions in 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.

[0032] 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.

[0033] 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.

[0034] In some optional embodiments, the porous material is granular, 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.

[0035] In some optional embodiments, the mass content of the lithium salt is 1% to 10% based on the total mass of the positive electrode active material film.

[0036] 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.

[0037] In some alternative embodiments, the lithium-conducting binder includes one or more of polyacrylonitrile and polycaprolactone.

[0038] 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 a conduction channel for lithium ions to jump along the aforementioned group sites. Furthermore, the lithium-conducting binder, lithium salt, and plasticizer 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 the lithium-conducting binder, it can improve the cycle life and interfacial stability of lithium metal battery cells.

[0039] 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.

[0040] 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.

[0041] In some optional embodiments, the positive electrode active material film layer comprises a positive electrode active material with a mass content of 80% to 98%, wherein the positive electrode active material comprises one or more of lithium-containing transition metal oxides and lithium-containing transition metal phosphates.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In some optional embodiments, the mass ratio of the long-range conductive carbon to the short-range conductive carbon is 1:(0.5 to 5).

[0048] 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.

[0049] In some alternative embodiments, the long-range conductive carbon includes one or more of vapor-grown carbon fibers and carbon nanotubes.

[0050] In some optional embodiments, the short-range conductive carbon includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, and carbon dots.

[0051] In some optional embodiments, the solid electrolyte includes one or more of oxide-based solid electrolytes, sulfide-based solid electrolytes, polyoxyethylene electrolytes, and organic-inorganic composite electrolytes composed of polyoxyethylene and inorganic substances.

[0052] 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.

[0053] In some optional embodiments, 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.

[0054] 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.

[0055] Secondly, embodiments of this application provide a method for preparing a positive electrode sheet for a lithium metal battery cell, comprising:

[0056] A positive electrode active material slurry is coated onto a positive electrode current collector to obtain an initial positive electrode sheet, wherein the positive electrode active material slurry includes a lithium binder and a lithium salt;

[0057] The liquid plasticizer is implanted into the initial positive electrode sheet by any one or more of the following methods: immersion, dripping, coating, and spraying, to obtain the positive electrode sheet.

[0058] In the preparation method of this application embodiment, a liquid plasticizer is implanted into the initial positive electrode sheet. The electron-rich functional groups of the liquid 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. This constructs a high-speed ion conduction channel and improves the ionic conductivity of the positive electrode active material film layer. Furthermore, the lithium-conducting binder, lithium salt, and liquid plasticizer included in the positive electrode active material film layer further promote the dissociation of the lithium salt, further improving the kinetic performance of the lithium metal battery cell.

[0059] In the embodiments of this application, the positive electrode active material film layer includes a liquid plasticizer, which is used to dissociate and / or disperse the lithium salt. Due to the presence of the liquid plasticizer, the 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.

[0060] Thirdly, embodiments of this application provide a method for preparing a lithium metal battery cell, comprising:

[0061] A positive electrode sheet is provided, the positive electrode sheet comprising 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 comprising a lithium-conductive binder, a lithium salt and a liquid plasticizer or the positive electrode sheet is prepared by the preparation method of the second aspect;

[0062] The positive electrode is assembled with a lithium metal negative electrode and an electrolyte to obtain the lithium metal battery cell, wherein the positive active material film and the electrolyte contain a film-like liquid plasticizer.

[0063] In the preparation method of this application embodiment, the liquid plasticizer is located on the positive electrode sheet. The electron-rich functional groups of the liquid 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. This constructs a high-speed ion conduction channel and improves the ionic conductivity of the positive electrode active material film. The lithium-conducting binder has a high electron density and / or has negatively charged (lone pair electron) groups, which can participate in the dissociation of the lithium salt and provide a conduction channel for lithium ions to jump along the above-mentioned group sites. The lithium-conducting binder and plasticizer included in the positive electrode active material film jointly construct a high-speed ion conduction channel network, thereby improving the dynamic performance of the lithium metal battery cell.

[0064] Fourthly, embodiments of this application provide a battery device comprising a lithium metal battery cell as described in the first aspect or a lithium metal battery cell prepared by the method described in the third aspect. The battery device of this application comprises the lithium metal battery cell of the first aspect of this application, and therefore possesses at least the advantages corresponding to the lithium metal battery cell.

[0065] Fifthly, embodiments of this application provide an electrical device including the battery device described in the fourth aspect, for storing or providing electrical energy. The electrical device of this application includes the aforementioned lithium metal battery cell, and therefore possesses at least the advantages corresponding to a battery device. Attached Figure Description

[0066] 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.

[0067] Figure 1 A schematic diagram of one embodiment of the lithium metal battery cell of this application is shown.

[0068] Figure 2 It shows Figure 1 An exploded view of one embodiment of a lithium metal battery cell is shown.

[0069] Figure 3 A schematic diagram of the battery pack according to one embodiment of this application is shown.

[0070] Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0071] Figure 5 A schematic diagram of one embodiment of an electrical device incorporating the lithium metal battery cell of this application as a power source is shown.

[0072] Figure 6 Impedance curves of the positive electrode sheets of Embodiment 1 and Comparative Examples 1-2 of this application are shown.

[0073] Figure 7 The circuit capacity retention curve of the battery cell of Embodiment 1 of this application is shown.

[0074] The accompanying drawings are not necessarily drawn to scale.

[0075] 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 metal battery cell. Detailed Implementation

[0076] The following detailed description, with appropriate reference to the accompanying drawings, discloses the electrolyte for lithium metal battery cells, methods for preparing the electrolyte therefrom, embodiments of the lithium metal battery cells, and power-consuming devices. However, unnecessary details may be omitted. For example, detailed descriptions of well-known facts 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 a full understanding of this application by those skilled in the art and are not intended to limit the subject matter of the claims.

[0077] 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 the 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 specific parameters, 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, characterized in that a and b are both 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.

[0078] 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.

[0079] 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.

[0080] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, if a 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 it is mentioned that 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.

[0081] 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.

[0082] 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.

[0083] 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).

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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 This is an example of a rectangular lithium metal battery cell 5.

[0091] 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.

[0092] In some alternative embodiments, lithium metal battery cells can be assembled into battery modules, and the number of lithium metal battery cells contained in a battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 2 This is a schematic diagram of battery module 4 as an example. Figure 2 As shown, in battery module 4, multiple lithium metal battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple lithium metal battery cells 5 can be fixed in place using fasteners.

[0093] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple lithium metal battery cells 5 are received.

[0094] 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.

[0095] Figure 3 and Figure 4 This is a schematic diagram of battery pack 1 as an example. Figure 3 and Figure 4 As shown, 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. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0096] 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.

[0097] 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.

[0098] 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).

[0099] According to some optional embodiments provided in this application, a lithium metal battery cell is provided, including a lithium metal negative electrode, an electrolyte 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 liquid plasticizer.

[0100] The liquid plasticizer is present in a membrane form between the positive electrode active material film layer and the electrolyte.

[0101] In this embodiment, the electron-rich functional groups or electron-rich structures of the liquid plasticizer can interact with lithium salt, promoting the dissociation of lithium salt and forming a region with a local high concentration of lithium ions in situ. The liquid plasticizer is distributed in the positive electrode active material film layer, constructing a high-speed ion conduction channel and improving the ionic conductivity of the positive electrode active material film layer. The lithium-conducting binder has a high electron density and / or has negatively charged (lone pair electron) groups, which can participate in the dissociation of lithium salt and provide a conduction channel for lithium ions to jump along the above-mentioned group sites. The liquid plasticizer in a film form is included between the positive electrode active material film layer and the electrolyte, which is beneficial to the transport of lithium ions and comprehensively improves the dynamic performance of the lithium metal battery cell.

[0102] In the embodiments of this application, the positive electrode active material film layer includes a liquid plasticizer. Due to the presence of the liquid plasticizer, the liquid plasticizer has oxidation-resistant functional groups, which inhibit the interfacial side reactions between the positive electrode sheet and the electrolyte, improve the stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell, and improve the cycle life of the lithium metal battery cell.

[0103] In the embodiments of this application, the positive electrode active material film layer includes a liquid plasticizer. Due to the presence of the liquid plasticizer, it has oxidation-resistant functional groups, such as C≡N bonds and S=O bonds, which suppress interfacial side reactions between the positive electrode sheet and the electrolyte, improve the stability between the positive electrode active material film layer and the electrolyte of the lithium metal battery cell, and improve the cycle life of the lithium metal battery cell.

[0104] Generally, it is difficult for the electrolyte to adhere completely and tightly to the positive electrode active material film layer, resulting in limited pathways for active ions. In the embodiments of this application, at least a portion of the surface of the electrolyte near the positive electrode sheet includes the liquid plasticizer. The liquid plasticizer at this location allows for better contact between the electrolyte and the positive electrode active material film layer, increasing the active ion transport pathways and improving the kinetic performance of the lithium metal battery cell.

[0105] In some alternative embodiments, the concentration of liquid plasticizer in at least a portion of the positive electrode active material film layer decreases along the direction from the positive electrode current collector.

[0106] Generally, during the cycling process of a lithium metal battery cell, the surface of the positive electrode active material film layer will come into contact with and accommodate more active ions, while the positive electrode active material film layer closer to the positive electrode current collector will accommodate fewer active ions compared to its surface.

[0107] In this embodiment, along the direction from the positive electrode active material film to the positive electrode current collector, the concentration of liquid plasticizer in at least a portion of the positive electrode active material film decreases. This facilitates the uniform distribution of a relatively large number of active ions on the surface of the positive electrode active material film within the liquid plasticizer (where the liquid plasticizer content is relatively high). Conversely, a relatively small number of active ions are distributed within the liquid plasticizer near the positive electrode current collector (where the liquid plasticizer content is relatively low). This arrangement fully utilizes the liquid plasticizer, improves the uniform distribution of active ions along the thickness of the positive electrode active material film, increases the cycle life of the lithium metal battery cell, reduces the likelihood of incomplete reaction and lithium plating due to a large number of surface-mounted active ions, and lowers the probability or proportion of dead lithium.

[0108] 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 liquid plasticizer is 0.5% to 10%.

[0109] Optionally, based on the total mass of the positive electrode active material film, the mass content of the liquid 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%.

[0110] In some optional embodiments, the liquid plasticizer content is 2% to 5% by mass, based on the total mass of the positive electrode active material film. Therefore, an appropriate proportion 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 liquid plasticizer improves the 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.

[0111] In some optional embodiments, the liquid plasticizer includes one or more of carbonates, phosphate esters, nitrile compounds, and ionic liquids. These liquid plasticizers possess high electron density and / or negative charge (lone pairs of electrons), enabling them to effectively solubilize lithium ions, stably dissociate lithium ions, promote the dissociation of lithium salts, or effectively reduce the lattice energy of lithium salts, making them easier to dissociate and thus improving the overall lithium ion mobility and the kinetic performance of lithium metal battery cells.

[0112] 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 this field. For example, liquid plasticizers can be detected by methods such as gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), inductively coupled plasma optical emission spectrometry (ICP-OES), infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance.

[0113] For example, infrared spectroscopy can be used to identify compounds contained in the positive electrode active material film layer, such as the characteristic peak of the cyano group in nitrile compounds at 2240 cm⁻¹. -1 -2260cm -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.

[0114] In some optional embodiments, the nitrile compounds include one or more of monocyano nitrile compounds and aromatic nitrile compounds.

[0115] Nitrile compounds can be understood as nitrile compounds that are liquid at room temperature.

[0116] Monocyano compounds typically exhibit high chemical stability, reducing side reactions when in contact with electrolytes and cathode materials, thereby improving the long-term stability of lithium metal battery cells. Monocyano compounds can also reduce interfacial impedance, thus improving the kinetic performance of lithium metal battery cells. In some optional embodiments, the monocyano nitrile compound includes one or more of acetonitrile, propionitrile, and isopropionitrile.

[0117] Aromatic nitrile compounds possess π electrons, exhibiting good electronic conductivity. Aromatic monocyano compounds can enhance interfacial contact with electrode materials through π-π interactions and hydrogen bonding, thereby improving battery conductivity. Aromatic nitrile compounds typically possess good thermal stability, which contributes to improving the structural stability and high-temperature resistance of lithium metal battery cells. In some optional embodiments, the aromatic nitrile compound includes one or more of benzonitrile, o-phthalonitrile, and terephthalonitrile.

[0118] In summary, the specific structure of nitrile compounds can improve the conductivity and thermal stability of the positive electrode, thereby enhancing the cycle life and kinetic performance of lithium metal battery cells.

[0119] In some alternative embodiments, the carbonate includes one or more of dimethyl carbonate, diethyl carbonate, propylene carbonate, and methyl ethyl carbonate.

[0120] Carbonate can be understood as a liquid carbonate at room temperature, such as below 25 degrees Celsius. Liquid carbonate has a wide operating temperature range, can remain liquid at room temperature, and exhibits good stability in high or low temperature environments, improving battery cycle life and reliability. Compared to succinic anhydride, liquid carbonate has a wider operating temperature range and better ionic conductivity.

[0121] In some optional embodiments, the phosphate ester includes one or more of tri(ethyl) phosphate, tri(butyl) phosphate, tri(isooctyl) phosphate, tri(2-ethylhexyl) phosphate, and diisopropyl phosphate.

[0122] Phosphate esters can be understood as phosphate esters that are liquid at room temperature.

[0123] Liquid phosphate esters typically offer superior chemical stability, ionic conductivity, interfacial modification effects, and temperature adaptability. Specifically, phosphate esters generally exhibit high chemical stability and low reactivity, demonstrating good resistance to chemical corrosion under battery operating conditions and being less prone to side reactions with electrodes or electrolytes. Phosphate esters are compatible with many electrolyte and electrode materials, forming stable battery structures. Their high ionic conductivity effectively enhances the ionic conductivity of the electrolyte. They help reduce the electrolyte impedance of the battery, thereby increasing the battery's power density and charge / discharge rate.

[0124] In some optional embodiments, the ionic liquid includes one or more of imidazole ionic liquids, ammonium ionic liquids, pyridine ionic liquids, pyrrolidine ionic liquids, piperidine ionic liquids, amino acid ionic liquids, and phosphate ester ionic liquids.

[0125] Ionic liquids are liquids composed of two or more ions that are liquid at or near room temperature, such as 20 to 25°C. Ionic liquids typically consist of an organic cation and an inorganic or organic anion.

[0126] Phosphate esters are esterified derivatives of phosphoric acid. Phosphate ester ionic liquids consist of a phosphate ester group combined with a cation and an anion. For example, tributyl phosphate (TnBP) acts as a cation, combined with various anions such as BF4-, PF6-, and FSI. - TFSI - These substances combine to form ionic liquids. Phosphate esters and phosphate ester ionic liquids are two different types of substances.

[0127] For example, the ionic liquid state can be 1-propyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethylpyridine bis(trifluoromethanesulfonyl)imide, tributylmethylammonium bis(trifluoromethanesulfonyl)imide, etc.

[0128] In some alternative embodiments, the liquid plasticizer includes one or more of cyano, sulfur-oxygen double bond, and carbonyl.

[0129] 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 lithium ions, promoting the dissociation of lithium salts, or effectively reducing the lattice energy of lithium salts, making lithium salts easier to dissociate, increasing the degree of dissociation of lithium salts, and comprehensively improving the mobility of lithium ions and the kinetic performance of lithium metal battery cells.

[0130] In some optional embodiments, the positive electrode active material film layer comprises a porous material, which includes one or more of aerogels, molecular sieves, porous organic framework materials, and porous metal-organic frameworks.

[0131] The active sites on the surface of porous materials promote the dissociation of lithium salts, further promoting the interaction between liquid plasticizers and lithium salt cations, thus accelerating lithium salt dissociation and comprehensively constructing high-speed ion conduction channels to improve 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 lithium ion dissociation by forming hydrogen bonds or through acid-base interactions. Metal ions (such as zinc, copper, and aluminum) in MOFs have different oxidation states and coordination environments; these metal centers can interact with lithium ions, aiding in lithium ion dissociation.

[0132] In the embodiments of this application, the porous characteristics of the porous material can accommodate the activated liquid plasticizer, restrict the flow of the liquid plasticizer, and make at least part of the surface of the porous material gel-like, thereby comprehensively improving the stability of the positive electrode active material film and increasing the cycle life of the lithium metal battery cell; the liquid plasticizer and dissociated lithium ions in the pores of the porous material also form a high-concentration lithium ion region, creating a high-speed ion conduction channel, further improving the kinetic performance of the lithium metal battery cell.

[0133] Porous organic frameworks (COFs) and porous metal-organic frameworks (MOFs) are both materials with highly ordered porous structures. The pore network of COFs is connected 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.

[0134] 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 aluminosilicate molecular sieves, mesoporous aluminosilicate molecular sieves, or macroporous aluminosilicate molecular sieves.

[0135] 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.

[0136] 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.

[0137] 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. 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 salts, increasing the ionic conductivity of the positive electrode active material film. The plasticizers and dissociated lithium ions in 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.

[0138] 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.

[0139] 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.

[0140] In some optional embodiments, the porous material is granular, 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.

[0141] In some optional embodiments, the mass content of the lithium salt is from 1% to 10% based on the total mass of the positive electrode active material film. Optionally, 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% based on the total mass of the positive electrode active material film.

[0142] 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.

[0143] In some alternative embodiments, the lithium-conducting binder includes one or more of polyacrylonitrile and polycaprolactone.

[0144] 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.

[0145] 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, the lithium-conducting binder, lithium salt, and plasticizer together construct a high-concentration lithium-ion region, creating a high-speed ion conduction channel and improving the kinetic performance of lithium metal battery cells. The lithium-conducting binder 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 the lithium-conducting binder, it can improve the cycle life and interfacial stability of lithium metal battery cells.

[0146] 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. Optionally, 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% based on the total mass of the positive electrode active material film. 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 improving the cycle life and stability of the lithium metal battery cell.

[0147] In some alternative embodiments, the weight-average molecular weight of polyacrylonitrile is from 50,000 to 500,000.

[0148] 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.

[0149] 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.

[0150] In some optional embodiments, the weight-average molecular weight of polycaprolactone is from 10,000 to 100,000.

[0151] 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.

[0152] In some optional embodiments, the ionic conductivity of the positive electrode is 1×10⁻⁶. -4 S / cm to 1S / cm.

[0153] 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 -4 S / 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 -2S / 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.

[0154] In some optional embodiments, the positive electrode active material film layer comprises a positive electrode active material with a mass content of 80% to 98%, wherein the positive electrode active material comprises one or more of lithium-containing transition metal oxides and lithium-containing transition metal phosphates.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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 LiNi0.5 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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. Optionally, the mass content of the conductive agent can be any value or a range of combinations thereof from 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0% based on the total mass of the positive electrode active material film.

[0166] In some optional embodiments, the mass ratio of the long-range conductive carbon to the short-range conductive carbon is 1:(0.5 to 5).

[0167] 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, and 1:5.0.

[0168] 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.

[0169] In some alternative embodiments, the long-range conductive carbon includes one or more of vapor-grown carbon fibers and carbon nanotubes.

[0170] In some optional embodiments, the short-range conductive carbon includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, and carbon dots.

[0171] 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.

[0172] 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.

[0173] 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.).

[0174] [Preparation method of positive electrode sheet]

[0175] This application provides a method for preparing a positive electrode sheet for a lithium metal battery cell, comprising:

[0176] A positive electrode active material slurry is coated onto a positive electrode current collector to obtain an initial positive electrode sheet, wherein the positive electrode active material slurry includes a lithium binder and a lithium salt;

[0177] The liquid plasticizer is implanted into the initial positive electrode sheet by any one or more of the following methods: immersion, dripping, coating, and spraying, to obtain the positive electrode sheet.

[0178] In the preparation method of this application embodiment, a liquid plasticizer is implanted into the initial positive electrode sheet. The electron-rich functional groups of the liquid 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. This constructs a high-speed ion conduction channel and improves the ionic conductivity of the positive electrode active material film. The lithium-conducting binder has a high electron density and / or has negatively charged (lone pair electron) groups, which can participate in the dissociation of the lithium salt and provide a conduction channel for lithium ions to jump along the above-mentioned group sites. The lithium-conducting binder and plasticizer included in the positive electrode active material film jointly construct a high-speed ion conduction channel network, thereby improving the dynamic performance of the lithium metal battery cell.

[0179] In the embodiments of this application, the positive electrode active material film layer includes a liquid plasticizer, which is used to dissociate and / or disperse the lithium salt. Due to the presence of the liquid plasticizer, the 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.

[0180] [Electrolytes]

[0181] 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.

[0182] Electrolytes can include electrolyte salts and solvents.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] In some optional embodiments, the solid electrolyte includes one or more of oxide-based solid electrolytes, sulfide-based solid electrolytes, polyoxyethylene electrolytes, and organic-inorganic composite electrolytes composed of polyoxyethylene and inorganic substances.

[0187] 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.

[0188] 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.

[0189] In some optional embodiments, 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.

[0190] In this embodiment, the liquid organic solvent can be one or more of carbonates, nitriles, and ionic liquids.

[0191] 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.

[0192] Semi-solid electrolytes can be understood as gel electrolytes, which may include polymers as a backbone network and can be used in conjunction with ionic liquids—lithium salts.

[0193] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0194] 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.

[0195] 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.

[0196] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0197] [Negative electrode plate]

[0198] In some alternative embodiments, the negative electrode current collector includes one or more of elemental lithium and lithium alloys.

[0199] 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.

[0200] In some alternative embodiments, the metal material in the first metal layer may include one or more of elemental lithium and lithium alloys.

[0201] 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.

[0202] 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).

[0203] [Preparation methods for lithium metal battery cells]

[0204] This application provides a method for preparing a lithium metal battery cell, including:

[0205] A positive electrode sheet is provided, the positive electrode sheet comprising 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 comprising a lithium-conductive binder, a lithium salt and a liquid plasticizer, or the positive electrode sheet is prepared by the above preparation method;

[0206] The positive electrode is assembled with a lithium metal negative electrode and an electrolyte to obtain the lithium metal battery cell, wherein the positive active material film and the electrolyte contain a film-like liquid plasticizer.

[0207] In the preparation method of this application embodiment, the liquid plasticizer is located on the positive electrode sheet. The electron-rich functional groups of the liquid 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 liquid plasticizer included in the positive electrode active material film layer further promote the dissociation of the lithium salt, further improving the kinetic performance of the lithium metal battery cell.

[0208] 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 and the lithium metal negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer package, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a lithium metal battery cell is obtained. Multiple lithium metal battery cells can be further connected in series, parallel, or in a mixed configuration to form a lithium metal battery cell module. Multiple lithium metal battery cell modules can also be connected in series, parallel, or in a mixed configuration 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.

[0209] Electrical appliances

[0210] This application provides an electrical device, including the battery device described above, for storing or providing electrical energy.

[0211] 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.

[0212] 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.

[0213] Figure 5 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, lithium metal battery packs or lithium metal battery modules can be used.

[0214] 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.

[0215] This application provides an electrical device, which may also include any one or more of an energy storage device or energy storage system for storing or providing electrical energy.

[0216] Example

[0217] 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.

[0218] Example 1

[0219] Preparation of lithium metal battery cells:

[0220] Preparation of positive electrode sheet: Lithium iron phosphate (LiFePO4), conductive agent acetylene black, binder polyacrylonitrile (weight average molecular weight of 150,000), and lithium bis(fluorosulfonyl)imide are mixed in a mass ratio of 93:2:2:3. 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. After drying at room temperature, it is cold-pressed to obtain the initial positive electrode sheet, which includes an initial positive electrode active layer.

[0221] Liquid plasticizer propylene carbonate was added to the initial positive electrode sheet by drop coating, so that the mass ratio of plasticizer to initial positive electrode active layer was 5wt%:95wt%. Then it was cut into rectangles to form the positive electrode sheet. The mass content of propylene carbonate in the final positive electrode active material film layer was 5%.

[0222] Negative electrode: A lithium metal sheet (lithium metal element) with a thickness of 60μm;

[0223] Electrolyte: 30μm PEO / LTFSI composite electrolyte membrane, wherein the mass ratio of polyethylene oxide (PEO):LiTFSI:lithium lanthanum zirconium oxide is 6:2:2;

[0224] Separating membrane: None; the electrolyte described above provides this separation function.

[0225] 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.

[0226] Examples 2-6

[0227] The preparation method is similar to that of Example 1, except that the plasticizer propylene carbonate in the positive electrode active material film layer of Examples 2 to 6 is replaced by equal masses of 1-propyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 1-ethylpyridine bis(trifluoromethanesulfonyl)imide salt ionic liquid, tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt ionic liquid, and N-methyl-N-propylpiperidine bis(trifluoromethanesulfonyl)imide salt ionic liquid.

[0228] Examples 7-8

[0229] The preparation method is similar to that of Example 1, except that the plasticizer propylene carbonate in the positive electrode active material film layer in Examples 7 to 8 is replaced by equal masses of isopropionitrile and terephthalonitrile.

[0230] Examples 9-10

[0231] The preparation method is similar to that of Example 1, except that the plasticizer propylene carbonate in the positive electrode active material film layer in Examples 9 to 10 is replaced by equal masses of dimethyl carbonate and ethyl methyl carbonate.

[0232] Examples 11 to 12

[0233] The preparation method is similar to that of Example 1, except that the plasticizer propylene carbonate in the positive electrode active material film layer in Examples 11 to 12 is replaced by equal masses of tris(isooctyl) phosphate and tris(2-ethylhexyl) phosphate.

[0234] Example 13

[0235] The preparation method is similar to that in Example 1, except that the content of propylene carbonate plasticizer in the positive electrode sheet is different. The mass content of propylene carbonate in the final positive electrode active material film is 10%.

[0236] Example 14

[0237] The preparation method is similar to that in Example 1, except that the content of propylene carbonate plasticizer in the positive electrode sheet is different. The mass content of propylene carbonate in the positive electrode active material film layer is 0.5%.

[0238] Example 15

[0239] The preparation method is similar to that in Example 1, except that the content of propylene carbonate plasticizer in the positive electrode sheet is different. The mass content of propylene carbonate in the positive electrode active material film layer is 2.5%.

[0240] Example 16

[0241] The preparation method is similar to that in Example 1, except that the electrolyte is replaced with a 30-micron polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) gel electrolyte, wherein the mass ratio of PVDF-HFP:LiTFSI:ionic liquid is 5:2:3, and the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid.

[0242] Example 17

[0243] The preparation method is similar to that in Example 1, except that the binder in the positive electrode sheet is replaced with polycaprolactone.

[0244] Example 18

[0245] 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 (LiFePO4), acetylene black (conductive agent), polyacrylonitrile (weight-average molecular weight 150,000), lithium bis(fluorosulfonyl)imide, and porous material are mixed in a mass ratio of 92:2:2:3:1 to obtain the initial positive electrode sheet. Liquid plasticizer propylene carbonate is added to the initial positive electrode sheet using a drop-coating method, so that the mass ratio of plasticizer to the positive electrode active layer is 5 wt%:95 wt%. 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.

[0246] Example 19

[0247] The preparation method is similar to that in Example 18, except that the porous material is replaced with ZIF-8, with an average pore size of 10 nm, a porosity of >85%, and a volume average particle size Dv50 of 4 μm.

[0248] Example 20

[0249] The preparation method is similar to that in Example 18, except that the porous material is replaced with silica aerogel. The average pore size of the porous material is 20 nm, the porosity is 98%, and the volume average particle size Dv50 is 10 μm.

[0250] Example 21

[0251] The preparation method is similar to that in Example 18, except that the porous material is replaced with a microporous silica-alumina molecular sieve. The average pore size of the porous material is 2 nm, the porosity is 85%, and the volume average particle size Dv50 is 4 μm.

[0252] Example 22

[0253] The preparation method is similar to that in Example 1, except that the conductive agent in the positive electrode is different, the total mass fraction of the conductive agent remains the same, and the conductive agent includes long-range conductive carbon vapor-grown carbon fiber and the short-range conductive carbon superconducting carbon, with a mass ratio of 1:0.5 between the vapor-grown carbon fiber and the superconducting carbon.

[0254] Example 23

[0255] The preparation method is similar to that in Example 1, except that the conductive agent in the positive electrode is different, the total mass fraction of the conductive agent remains the same, and the conductive agent includes long-range conductive carbon vapor-grown carbon fiber and the short-range conductive carbon superconducting carbon, with a mass ratio of 1:5 between the vapor-grown carbon fiber and the superconducting carbon.

[0256] Example 24

[0257] The preparation method is similar to that in Example 1, except that the conductive agent in the positive electrode is different, the total mass fraction of the conductive agent remains the same, and the conductive agent includes long-range conductive carbon vapor-grown carbon fiber and the short-range conductive carbon superconducting carbon, with a mass ratio of 1:2 between the vapor-grown carbon fiber and the superconducting carbon.

[0258] Comparative Example 1

[0259] 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.

[0260] Comparative Example 2

[0261] 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.

[0262] Comparative Example 3

[0263] 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.

[0264] Test section

[0265] 1) Positive electrode ionic conductivity testing: The positive electrode was prepared according to the above examples and comparative examples, with the following differences: the conductive agent was removed to prevent internal short circuits; the positive electrode slurry was uniformly coated on both sides of the positive electrode current collector aluminum foil, and after drying to remove the slurry solvent, an initial positive electrode was obtained. A plasticizer was introduced into the initial positive electrode using a drop-coating method, ensuring a plasticizer to positive electrode active layer mass ratio of 5wt%:95wt%. Appropriately sized smooth aluminum foil was cut as the counter electrode, and assembled into an aluminum / aluminum symmetric battery. Electrochemical impedance spectroscopy was tested at 25°C using an electrochemical workstation to obtain the impedance of the positive electrode active material film layer; the ionic conductivity of the positive electrode active material film layer was calculated using the formula: ionic conductivity = positive electrode active material film layer thickness / (area * impedance value). The electrode area was 20.79 cm². 2 The thickness of Example 1 is 0.0056 cm.

[0266] The test results are shown in Table 1.

[0267]

[0268]

[0269] As shown in Table 1, the positive electrode sheets of Examples 1-12 contained plasticizers and lithium-conducting binders, while at least one of them was not added in Comparative Examples 1-3. The positive electrode sheets of Examples 1-12 achieved better ionic conductivity.

[0270] Compared to Example 1, Examples 13-15 show different plasticizer contents in the positive electrode sheet. When the plasticizer content is between 5% and 10%, the ionic conductivity of the positive electrode sheet is better than when the plasticizer content is between 0.5% and 2.5%. Compared to Example 1, Examples 16-17 show different types of lithium-conductive binders and electrolytes, which to some extent affect the ionic conductivity of the positive electrode sheet.

[0271] Compared to Example 1, Examples 18-21 incorporate porous materials in the positive electrode, thereby improving the ionic conductivity of the positive electrode compared to the positive electrode of Example 1.

[0272] 2) Cycle life test of lithium metal battery cells: The ambient temperature for cell cycling was set to 60℃, and charge-discharge cycles were performed using a rate of 0.1C (i.e., 7mA). The cut-off voltages for charging and discharging were set to 3.8V-2.0V 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 the cycle life of the lithium metal battery cell.

[0273] The test results are shown in Table 2.

[0274]

[0275]

[0276] Figure 6 Impedance curves of the positive electrode sheets of Example 1 and Comparative Examples 1-2 of this application are shown. This illustrates that the positive electrode sheet of Example 1, with the addition of lithium-conducting additives and plasticizers, exhibits lower impedance and improved ionic conductivity compared to Comparative Examples 1-2, which did not contain lithium-conducting additives or plasticizers.

[0277] Figure 7 The diagram shows the cycle capacity retention curve of the lithium metal battery cell of Example 1 of this application, illustrating that the addition of polyacrylonitrile and propylene carbonate in Example 1 gives the lithium metal battery cell good cycle life.

[0278] As shown in Table 1, compared with Comparative Examples 1-3, Examples 1 to 12 have added lithium-conducting additives and liquid plasticizers to their positive electrode sheets, which improves the cycle life of lithium metal battery cells.

[0279] Compared to Example 1, Examples 13-15 show different plasticizer contents in the positive electrode sheet. When the plasticizer content is between 5% and 10%, the cycle life of the lithium metal battery cell is better than when the plasticizer content is between 0.5% and 2.5%. Compared to Example 1, Examples 16-17 show different types of lithium-conducting binders and electrolytes, which to some extent affect the cycle life of the lithium metal battery cell.

[0280] Compared to Example 1, Examples 18-21 incorporated porous materials into the positive electrode, thereby improving the cycle life of the lithium metal battery cell compared to the lithium battery cell of Example 1. Examples 22-24, compared to Example 1, incorporated long-range conductive carbon and short-range conductive carbon into the positive electrode, further improving the cycle life of the lithium metal battery cell compared to the lithium battery cell of Example 1.

[0281] 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, characterized in that, The application relates to a lithium metal negative electrode sheet, an electrolyte and a positive electrode sheet, characterized in that the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material film layer arranged on at least one side of the positive electrode current collector, the positive electrode active material film layer comprising a lithium-conducting binder, a lithium salt and a liquid plasticizer; and the electrolyte comprises a solid electrolyte or a semi-solid electrolyte. The positive electrode active material film layer and the electrolyte comprise the film-shaped liquid plasticizer.

2. The lithium metal battery cell of claim 1, wherein, In the direction from the positive electrode active material film layer to the positive electrode current collector, the liquid plasticizer concentration of at least part of the positive electrode active material film layer has a decreasing trend.

3. The lithium metal battery cell according to claim 1 or 2, c h a r a c t e r i z e d in that The mass content of the liquid plasticizer is 0.5% to 10% based on the total mass of the positive electrode active material film layer.

4. The lithium metal battery cell according to any one of claims 1 to 3, characterized in that The mass content of the liquid plasticizer is 2% to 5% based on the total mass of the positive electrode active material film layer.

5. The lithium metal battery cell according to any one of claims 1 to 4, characterized in that, The liquid plasticizer comprises one or more of carbonates, phosphates, nitrile compounds and ionic liquids.

6. The lithium metal battery cell of claim 5, wherein, The liquid plasticizer satisfies one or more of the following conditions: 1) the nitrile compound comprises one or more of monocyano nitrile compounds and aromatic nitrile compounds; 2) the carbonate comprises one or more of dimethyl carbonate, diethyl carbonate, propylene carbonate and methyl ethyl carbonate; 3) the phosphate comprises one or more of phosphate tri(ethyl) phosphate, tri(butyl) phosphate, tri(isooctyl) phosphate, tri(2-ethylhexyl) phosphate and diisopropyl phosphate; 4) the ionic liquid comprises one or more of imidazole ionic liquid, ammonium ionic liquid, pyridine ionic liquid, pyrrolidine ionic liquid, piperidine ionic liquid, amino acid ionic liquid and phosphate ionic liquid; 5) the liquid plasticizer comprises one or more of cyano, sulfur-oxygen double bond and carbonyl.

7. The lithium metal battery cell according to any one of claims 1 to 6, characterized in that The positive electrode active material film layer comprises a porous material, and the porous material comprises one or more of aerogel, molecular sieve porous organic framework material and porous metal organic framework.

8. The lithium metal battery cell of claim 7, wherein, The porous material satisfies one or more of the following conditions: 1) the mass content of the porous material is 0.5% to 3% based on the total mass of the positive electrode active material film layer; 2) the average pore size of the porous material is 0.3nm to 50nm; 3) the porosity of the porous material is 80% to 99.8%; 4) the volume average particle size Dv50 of the porous material is 1um to 6um.

9. The lithium metal battery cell of any one of claims 1-8, wherein, The positive electrode sheet satisfies one or more of the following conditions: 1) the mass content of the lithium salt is 1% to 10% based on the total mass of the positive electrode active material film layer; 2) the lithium salt comprises one or more of lithium bisfluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium bisoxalate borate, lithium difluoro oxalate borate, lithium difluoro bisoxalate phosphate and lithium tetrafluoro oxalate phosphate; 3) the lithium-conducting binder comprises one or more of polyacrylonitrile and polycaprolactone; 4) the mass content of the lithium-conducting binder is 1% to 10% based on the total mass of the positive electrode active material film layer. 5) the positive electrode tab has an ionic conductivity of 1 x 10 -4 S / cm to 1 S / cm.

10. The lithium metal battery cell of any one of claims 1-9, wherein, The positive electrode active material film layer comprises 80% to 98% of positive electrode active material, and the positive electrode active material comprises one or more of lithium-containing transition metal oxide and lithium-containing transition metal phosphate.

11. The lithium metal battery cell of any one of claims 1-10, wherein, The positive electrode active material film layer comprises conductive agent, and the conductive agent comprises long-range conductive carbon and short-range conductive carbon.

12. The lithium metal battery cell of claim 11, wherein, The conductive agent satisfies one or more of the following conditions: 1) The mass content of the conductive agent is 0.5% to 3% based on the total mass of the positive electrode active material film layer; 2) The mass ratio of the long-range conductive carbon to the short-range conductive carbon is 1:(0.5-5); 3) The long-range conductive carbon comprises one or more of vapor-grown carbon fiber and carbon nanotube; 4) The short-range conductive carbon comprises one or more of superconducting carbon, acetylene black, carbon black, ketjen black and carbon dots.

13. The lithium metal battery cell of any one of claims 1-12, characterized in that, The solid-state electrolyte comprises one or more of oxide-based solid-state electrolyte, sulfide-based solid-state electrolyte, polyethylene oxide-based electrolyte and organic-inorganic composite electrolyte composed of polyethylene oxide and inorganic matter.

14. The lithium metal battery cell of any one of claims 1-12, characterized in that, The semi-solid-state electrolyte comprises one or more of polyvinylidene-hexafluoropropylene copolymer gel electrolyte, polyvinylidene fluoride containing liquid organic solvent, polyethylene oxide containing liquid organic solvent, polyacrylonitrile containing liquid organic solvent, polymethyl methacrylate-based gel electrolyte containing liquid organic solvent and covalent organic framework-based gel electrolyte containing ionic liquid electrolyte.

15. A method for making a positive electrode sheet for a lithium metal battery cell, characterized by, The method comprises: coating positive electrode active material slurry on positive electrode current collector to obtain initial positive electrode sheet, wherein the positive electrode active material slurry comprises lithium-based binder and lithium salt; implanting liquid plasticizer into the initial positive electrode sheet by any one or more of infiltration, drop coating, coating and spraying to obtain the positive electrode sheet.

16. A method of producing a lithium metal battery cell, characterized by, The method comprises: providing positive electrode sheet, wherein the positive electrode sheet comprises positive electrode current collector and positive electrode active material film layer arranged on at least one side of the positive electrode current collector, and the positive electrode active material film layer comprises lithium-based binder, lithium salt and liquid plasticizer or is prepared by the preparation method of claim 15; assembling the positive electrode sheet with lithium metal negative electrode sheet and electrolyte to obtain the lithium metal battery cell, wherein the positive electrode active material film layer and the electrolyte comprise film-shaped liquid plasticizer.

17. The production method according to claim 15 or 16, characterized in that, The positive electrode active material film layer comprises porous material, and the porous material comprises one or more of aerogel, molecular sieve, porous organic framework material and porous metal organic framework.

18. The method of claim 17, wherein, The porous material satisfies one or more of the following conditions: 1) The mass content of the porous material is 0.5% to 3% based on the total mass of the positive electrode active material film layer; 2) The average pore size of the porous material is 0.3nm-50nm; 3) The porosity of the porous material is 80%-99.8%; 4) The volume average particle size Dv50 of the porous material is 1μm-6μm. 5) the positive electrode tab has an ionic conductivity of 1 x 10 -4 S / cm to 1 S / cm.

19. A battery device characterized by comprising: The lithium metal battery cell prepared by the preparation method of any one of claims 15-18.

20. An electrical device, comprising: The battery device of claim 19, for storing or providing electrical energy.

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