A battery monomer, a preparation method thereof, a battery device, and an energy storage device

Abstract

The application relates to the technical field of energy storage, and provides a battery monomer, a preparation method of the battery monomer, a battery device and an energy storage device. The battery monomer comprises: an electrode core assembly, the electrode core assembly comprises a negative electrode sheet, a diaphragm and a positive electrode sheet which are arranged in a stack; a shell, the electrode core assembly is located in the shell; and an electrolyte, the electrolyte is located in the shell; the positive electrode sheet comprises a lithium supplementing material, and a molecular formula of the lithium supplementing material is Li x MO4@A, wherein M is Mo or Al, A is S, Se or Te, and x=2 or 5. The technical scheme provided by the application has at least the following advantages: through combination of positive electrode lithium supplementing material design and in-situ interface polymerization of electrolyte, the problems of active lithium loss, electrolyte dryness and insufficient interface stability in a liquid lithium iron phosphate battery are effectively solved.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a battery cell and its preparation method, a battery device, and an energy storage device. Background Technology

[0002] Traditional liquid lithium iron phosphate batteries suffer from continuous loss of active lithium during cycling due to the formation and thickening of the solid electrolyte interphase (SEI) film, leading to capacity decay. Simultaneously, the liquid electrolyte is prone to evaporation, leakage, or localized drying during long-term cycling or storage, causing deterioration of the electrode-electrolyte interface and affecting the battery's long-term stability and safety. Although studies have attempted improvements through cathode pre-lithiation or electrolyte additives, problems remain, including low lithium replenishment efficiency, poor polymerization controllability, and high patent barriers in material systems. Summary of the Invention

[0003] This application provides a battery cell and its preparation method, battery device, and energy storage device, which helps to solve the problem of continuous loss of active lithium caused by the formation and thickening of the solid electrolyte interface (SEI) film, thus resulting in capacity decay.

[0004] In a first aspect, this application provides a battery cell, comprising: A battery cell assembly, the battery cell assembly comprising a negative electrode, a separator and a positive electrode stacked together; The housing, in which the battery cell assembly is located; Electrolyte, wherein the electrolyte is located within the housing; The positive electrode includes a lithium replenishing material, the molecular formula of which is Li. x MO4@A, where M is Mo or Al, A is S, Se or Te, and x=2 or 5.

[0005] Optionally, the positive electrode sheet further includes a positive electrode active material, a conductive agent, and a binder, and the amount of the lithium replenishing material is 0.5% to 5% of the total mass of the positive electrode active material, the lithium replenishing material, the conductive agent, and the binder.

[0006] Optionally, the positive electrode active material includes at least one of LiFePO4, LiNiO2, and LiCoO2.

[0007] Secondly, this application provides a method for preparing a battery cell as described above, comprising: A battery cell assembly is provided, the battery cell assembly comprising a negative electrode, a separator and a positive electrode stacked together; A housing is provided to house the battery cell assembly within the housing; Provide electrolyte and inject the electrolyte into the housing; A formation process is performed to obtain battery cells; The positive electrode includes a lithium replenishing material with the molecular formula Li2MO4@A, where M is Mo or Al, A is S, Se or Te, and x=2 or 5.

[0008] Optionally, the method for preparing the lithium supplementation material includes: The lithium source and the M source are dissolved in a solvent to form a sol; Nanoparticles of element A are added to the sol, dispersed, dried, and calcined in an inert atmosphere to obtain the lithium supplement material. The M source is an aluminum source or a molybdenum source.

[0009] Optionally, the lithium source includes lithium acetate.

[0010] Optionally, the molybdenum source includes ammonium molybdate, and the aluminum source includes at least one of aluminum nitrate, aluminum isopropoxide, aluminum chloride, and aluminum sulfate.

[0011] Optionally, the calcination temperature is 300℃~600℃.

[0012] Thirdly, this application provides a battery device, including a battery cell as described above, or a battery cell obtained by the preparation method described above, wherein the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0013] Fourthly, this application provides an energy storage device, which includes a battery device as described above, the battery device being used to store electrical energy.

[0014] The technical solution provided in this application has at least the following advantages: This application effectively solves the problems of active lithium loss, electrolyte drying and insufficient interface stability in liquid lithium iron phosphate batteries by combining the design of positive electrode lithium replenishment materials with in-situ interfacial polymerization of electrolyte.

[0015] The battery cells provided in this application can be widely used in battery fields requiring high energy density and long cycle life, including high-end electric vehicle battery systems, portable electronic devices, and large-scale energy storage power stations. The battery cells provided in this application can achieve large-capacity energy storage, comprehensively improving energy density, cycle life, and safety performance. They can meet the needs of long-term energy storage, achieving 4 hours or more of long-term energy storage, for example, in energy storage scenarios of 5 hours, 6 hours, and 8 hours. Long-term energy storage refers to the ability to continuously discharge at rated power for 4 hours or even longer, or to achieve large-scale, low-cost energy storage for several days or months. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced 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 these drawings without creative effort.

[0017] Figure 1 A flowchart corresponding to the method for preparing a single battery cell provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the battery device provided in the embodiments of this application; Figure 3 for Figure 2 A schematic diagram of the decomposition process; In the diagram: 100, battery assembly; 10, housing; 20, individual battery cell; 11, first part; 12, second part. Detailed Implementation

[0018] As the background technology indicates, elements such as Te have certain biotoxicity, and their production, processing, battery recycling, and waste disposal require stricter environmental regulations, increasing the cost and complexity of the entire life cycle. Li5AlO4, Li2MoO4, Se, and Te are not currently mainstream raw materials for lithium-ion batteries, and their large-scale preparation processes, cost control, and quality standards are not mature. Introducing them into existing mature battery production lines requires additional equipment modifications and process verification.

[0019] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0022] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0023] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0024] In the description of embodiments of this application, the terms "about," "approximately," "roughly," or "about" for a numerical value referring to a specific parameter include the numerical value, and those skilled in the art will understand that the deviation from the numerical value is within the acceptable tolerance of the specific parameter. For example, "about" or "about" for a numerical value may include additional numerical values ​​that are in the range of 90.0% to 110.0% of the numerical value, such as in the range of 95.0% to 105.0%, 97.5% to 102.5%, 99.0% to 101.0%, 99.5% to 100.5%, or 99.9% to 100.1%.

[0025] In the accompanying drawings corresponding to the embodiments of this application, the thickness and / or area of ​​layers, films, panels, regions, etc., are enlarged for better understanding and ease of description. Throughout the specification, the same reference numerals denote the same elements. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0026] In the description of embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be an intermediate component between the two components. Conversely, when describing a component on the surface of another component, or a component "directly" on another component, or a component surface on which another component is formed or disposed, it indicates that there is no intermediate component between the two components. For simplicity and clarity, various components may be drawn at any scale. In the drawings, some components may be omitted for simplicity.

[0027] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "the component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0028] The “components” mentioned above can refer to layers, membranes, regions, parts, plates, or structures, etc.

[0029] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0030] In a first aspect, this application provides a battery cell, comprising: A battery cell assembly, the battery cell assembly comprising a negative electrode, a separator and a positive electrode stacked together; The housing, in which the battery cell assembly is located; Electrolyte, wherein the electrolyte is located within the housing; The positive electrode includes a lithium replenishing material, the molecular formula of which is Li. x MO4@A, where M is Mo or Al, A is S, Se or Te, and x=2 or 5.

[0031] Using Li x The MO4@A composite serves as a novel lithium supplement, replacing conventional lithium silicate-based materials. During battery cycling, this material, through its core component Li, [achieves lithium ionization / regeneration]. x The slow decomposition of MO4 releases active lithium ions to continuously compensate for the lithium consumed by SEI formation and repair. The alumina element coated in the shell can undergo controlled oxidation at the positive electrode potential, participating in subsequent interfacial gelation reactions and achieving coupling of material functions.

[0032] In particular, Li₂MoO₄@Te was chosen because of its decomposition voltage (~3.8V vs. Li₂MoO₄). + The / Li) voltage is slightly higher than the LFP (lithium iron phosphate) plateau voltage, ensuring slow decomposition during cycling along with the cathode delithiation process, rather than a concentrated reaction during the first charge. The oxidation potential of Te (~3.5-4.0V) overlaps with this range, causing its oxidation and lithium replenishment decomposition to be kinetically coupled in time and potential.

[0033] Traditional sulfur-induced polymerization produces complex byproducts. This system utilizes the high conductivity and moderate solubility of Te to propose a novel reaction pathway: Positive electrode: intermediates generated by the oxidation of Te (such as HTeO3) - Analogs) and oxidized EC (ethylene carbonate) (possibly EC) + (Free radical) reactions have a clearer pathway and fewer byproducts.

[0034] Anode: Polyselen / telluride / Te n 2-It is a stronger nucleophile and reducing agent, capable of more efficiently initiating the ring-opening decarboxylation of EC and preferentially copolymerizing with FEC (fluoroethylene carbonate). The introduction of the -F group into FEC gives the resulting polymer higher lithium-ion transference number and antioxidant / reduction stability.

[0035] The localized alkaline microenvironment provided by the decomposition of lithium supplements may catalyze the transformation of Te species; while the resulting gel layer stabilizes the interface, which in turn protects the lithium supplement particles and slows down their rapid decomposition. This positive feedback synergistic model is something that existing isolated additive systems cannot achieve.

[0036] Optionally, the positive electrode sheet further includes a positive electrode active material, a conductive agent, and a binder. The amount of the lithium replenishing material is 0.5% to 5% of the total mass of the positive electrode active material, the lithium replenishing material, the conductive agent, and the binder, specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, and 5%.

[0037] Optionally, the positive electrode active material includes at least one of LiFePO4, LiNiO2, and LiCoO2.

[0038] Optionally, the positive electrode may also include a positive current collector, a binder, and / or a conductive agent.

[0039] The positive electrode current collector can be a metal foil or a composite current collector. For example, the metal foil may include, but is not limited to, aluminum foil. The composite current collector may include a base layer and a metal layer located on at least one surface of the base layer. For example, the base layer may be a polymer material base layer, including but not limited to polypropylene (PP) base layer, polyethylene terephthalate (PET) base layer, polybutylene terephthalate (PBT) base layer, polystyrene (PS) base layer, or polyethylene (PE) base layer. The material of the metal layer may include, but is not limited to, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy.

[0040] The binder may be selected from one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), or polyacrylic acid (PAA). The conductive agent may be selected from one or more of conductive carbon black, superconducting carbon, Ketjen black, carbon dots, acetylene black, graphene, carbon nanotubes, carbon nanofibers, or graphite.

[0041] Optionally, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer comprising a negative electrode active material. As an example, the negative electrode current collector has two opposing surfaces, and the negative electrode film layer is disposed on either or both of the opposing surfaces of the negative electrode current collector.

[0042] The negative electrode current collector can be a metal foil or a composite current collector. For example, the metal foil may include, but is not limited to, copper foil. Composite and three-dimensional current collectors may include a base layer and a metal layer located on at least one surface of the base layer. For example, the base layer may be a polymer material base layer, including but not limited to polypropylene (PP) base layer, polyethylene terephthalate (PET) base layer, polybutylene terephthalate (PBT) base layer, polystyrene (PS) base layer, or polyethylene (PE) base layer. The material of the metal layer may include, but is not limited to, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy.

[0043] The negative electrode active material can be any negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material can be at least one of the following materials, including but not limited to: graphite, carbon materials, silicon-based materials, tin-based materials, or lithium titanate. Graphite can be artificial graphite or natural graphite. Carbon materials can be soft carbon or hard carbon. Silicon-based materials can be selected from at least one of elemental silicon, silicon oxide, silicon-carbon compounds, silicon-nitrogen compounds, and silicon alloys. Tin-based materials can be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other materials that can be used as negative electrode active materials for battery cells can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0044] The negative electrode film may also include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0045] The negative electrode film layer may also include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0046] The negative electrode film may also include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0047] Optionally, the membrane material can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. This application does not impose any particular limitation on the type of membrane; for example, a porous membrane with chemical and mechanical stability can be selected.

[0048] The separator can be a single-layer thin film or a multi-layer composite thin film; there are no particular restrictions. When the separator is a multi-layer composite thin film, the materials of each layer can be the same or different; there are no particular restrictions.

[0049] In some specific examples, the separator can include polypropylene (PP) separators, polyethylene (PE) separators, PP / PE / PP three-layer composite separators, ceramic-coated separators, high-strength polymer separators, or functionalized composite separators. PP and PE separators typically have a thickness of 12μm to 25μm and a porosity of 30% to 50%, exhibiting good mechanical strength and chemical stability. Ceramic-coated separators, with a coating of ceramic materials such as Al2O3, SiO2, and TiO2 (coating thickness 2μm to 5μm) on a polyolefin-based membrane, improve high-temperature resistance (thermal shut-off temperature >160℃) and puncture resistance. High-strength polymer separators (such as polyimide (PI), polyethylene terephthalate (PET), and aramid nanofiber separators) possess excellent mechanical properties and high-temperature resistance. Functionalized composite separators (such as separators containing solid electrolyte coatings or lithiophilic coatings) can further enhance lithium deposition stability.

[0050] The electrolyte 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. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0051] For example, the electrolyte is an electrolyte solution. The electrolyte solution consists of an electrolyte salt and a solvent.

[0052] For example, 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.

[0053] For example, solvents may be selected from 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 At least one of butyrolactone, sulfolane, dimethyl sulfone, methyl sulfone, and diethyl sulfone.

[0054] For example, the electrolyte may also include additives. These 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 performance of the battery cell, or additives that improve the high-temperature or low-temperature performance of the battery cell.

[0055] Secondly, this application provides a method for preparing a battery cell as described above, such as... Figure 1 As shown, it includes: S1. Provide a battery cell assembly, the battery cell assembly including a negative electrode sheet, a separator and a positive electrode sheet stacked together; S2. Provide a housing and place the battery cell assembly inside the housing; S3. Provide electrolyte and inject the electrolyte into the casing; S4. Perform the formation step to obtain battery cells; The positive electrode includes a lithium replenishing material with the molecular formula Li2MO4@A, where M is Mo or Al, A is S, Se or Te, and x=2 or 5.

[0056] Optionally, the method for preparing the lithium supplementation material includes: The lithium source and the M source are dissolved in a solvent to form a sol; Nanoparticles of element A are added to the sol, dispersed, dried, and calcined in an inert atmosphere to obtain the lithium supplement material. The M source is an aluminum source or a molybdenum source.

[0057] Optionally, the lithium source includes lithium acetate.

[0058] Optionally, the molybdenum source includes ammonium molybdate, and the aluminum source includes at least one of aluminum nitrate, aluminum isopropoxide, aluminum chloride, and aluminum sulfate.

[0059] Optionally, the calcination temperature is 300℃~600℃, specifically 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, or 600℃.

[0060] Thirdly, this application provides a battery device, such as Figure 2 and Figure 3 As shown, the battery device includes the battery cell as described above, or the battery cell obtained by the preparation method described above, and the battery device includes one or more of the following: battery module, battery pack, and energy storage battery.

[0061] Specifically, the battery device 100 includes a housing 10 and individual battery cells 20, with the individual battery cells 20 housed within the housing 10. The housing 10 provides space for the individual battery cells 20, and the housing 10 can have various structures.

[0062] In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, and together define a receiving space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, with the first portion 11 covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the receiving space; alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0063] In the battery device 100, the battery cell 20 can be a single cell or multiple cells. Multiple battery cells 20 can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or a combination thereof to form battery modules, which are then connected in series, parallel, or a combination thereof to form a whole, which is also housed within the housing 10.

[0064] The battery device 100 may also include other structures, for example, the battery device 100 may also include a busbar for realizing electrical connection between multiple battery cells 20.

[0065] Fourthly, this application provides an energy storage device, which includes a battery device as described above, the battery device being used to store electrical energy.

[0066] Energy storage devices include, but are not limited to, residential energy storage cabinets, commercial energy storage cabinets, energy storage containers, energy storage racks, energy storage power stations, energy storage battery packs, or portable energy storage systems. Energy storage devices may also include energy management systems (EMS), battery management systems (BMS), and power conversion systems (PCS).

[0067] Example 1 This embodiment provides a method for preparing a single battery cell, such as... Figure 1 As shown, it includes: S1. Provide a battery cell assembly, which includes a negative electrode, a separator, and a positive electrode stacked together; S2. Provide a housing to place the battery cell assembly inside the housing; S3. Provide electrolyte and inject electrolyte into the casing; S4. Perform the formation step to obtain battery cells; The methods for preparing the positive electrode include: LiFePO4, lithium supplement material, acetylene black, and polyvinylidene fluoride were added to N-methylpyrrolidone in a mass ratio of 96:1.2:1:1.8 and thoroughly mixed in a planetary mixer to form a homogeneous slurry. The above slurry is uniformly coated on the aluminum foil current collector, and the areal density is controlled to meet the design capacity. The solvent is completely removed by staged baking (e.g., initial baking at 80°C and vacuum drying at 120°C). The electrode sheet is compacted to increase its density, and then cut into the required size to obtain the positive electrode sheet; When calculating capacity, the following formula is used: Capacity = Positive electrode specific capacity × Positive electrode coating mass; Given a fixed number of layers that can be packed into the casing, the higher the areal density, the higher the capacity. The molecular formula of the lithium supplement material is Li2MoO4@Te, and the preparation methods include: Lithium acetate and ammonium molybdate are dissolved in deionized water to form a sol; After dispersing Te nanoparticles in the sol, the mixture was dried and calcined at 550°C in an inert atmosphere to obtain Li2MoO4@Te.

[0068] Methods for preparing negative electrode sheets include: Ingredients: Mix graphite, conductive carbon black, and sodium carboxymethyl cellulose in a mass ratio of 97:0.6:2.4, add deionized water, and stir evenly to form a negative electrode slurry; Coating: The negative electrode slurry is uniformly coated on one or both sides of the negative electrode current collector (such as copper foil), and the coating thickness is controlled. Drying: Place the coated electrode in an oven and dry at 90°C; Roll pressing: The dried electrode sheets are compacted to the target compaction density using a roller press; Slitting / Die-cutting: The rolled electrode sheets are slitting or die-cutting into the required size to obtain the negative electrode sheets; The diaphragm is made of commercially available polypropylene film; Battery assembly Verification tests were conducted using a 24Ah stacked small pouch cell with a single-layer stacked structure. The negative electrode (or a separator with a protective coating) treated with an interface protection layer was stacked sequentially with the positive electrode and separator, and then encapsulated using an aluminum-plastic film. Battery assembly was performed in a dry room with a dew point below -40°C. After assembly, the cells were dried in an 80°C vacuum oven for 12 hours to ensure the internal moisture content was below 50ppm.

[0069] The steps involved in the transformation include: The packaged battery is placed in an environment of 45℃ and left to stand for 4h~24h to allow the electrolyte to fully wet the battery and the Te nanoparticles to partially dissolve and diffuse.

[0070] The cathode was initially charged to 3.65V with a small current of 0.1C (this voltage is sufficient to oxidize Te but avoids violent solvent decomposition relative to the lithium iron phosphate platform), and then kept at a constant voltage for 8 hours within this voltage range. During this stage, the cathode undergoes oxidation and initial polymerization of Te.

[0071] Continue charging to the upper limit voltage (e.g., 3.65V), then discharge to the cutoff voltage to complete the first cycle. During this process, the Te species that diffuse to the negative electrode are reduced, initiating the reduction polymerization of EC / FEC and other substances on the negative electrode surface.

[0072] Example 2 This embodiment provides a method for preparing a battery cell. The difference from Embodiment 1 is that the mass ratio of LiFePO4, lithium replenishment material, acetylene black, and polyvinylidene fluoride is 97:1:1:1.

[0073] Example 3 This embodiment provides a method for preparing a battery cell, differing from Example 1 only in that the lithium supplementation material is Li₂MoO₄@Se. The preparation method is as follows: lithium acetate and ammonium molybdate are dissolved in a solvent to form a sol, then elemental Se nanoparticles are added, dispersed, dried, and calcined at 500°C in an inert atmosphere to obtain Li₂MoO₄@Se. The mass ratios of the components in the positive electrode and subsequent steps are the same as in Example 1.

[0074] Example 4 This embodiment provides a method for preparing a battery cell, differing from Example 1 only in that the lithium supplement material is Li5AlO4@S. The preparation method is as follows: lithium acetate and an aluminum source (aluminum nitrate Al(NO3)3·9H2O) are dissolved in a solvent to form a sol; elemental sulfur nanoparticles are added, dispersed, dried, and calcined at 500°C in an inert atmosphere to obtain Li5AlO4@S. The mass ratio of each component in the positive electrode and subsequent steps are the same as in Example 1.

[0075] Example 5 This embodiment provides a method for preparing a battery cell, differing from Embodiment 1 only in that the negative electrode active material uses a silicon-carbon composite material (graphite to SiO mass ratio of 9:1). The batching steps in the negative electrode preparation method are as follows: the silicon-carbon composite material (containing 10wt% SiO), conductive carbon black, SBR, and CMC are mixed in a mass ratio of 94:2:2:2, and deionized water is added and stirred evenly to form a negative electrode slurry. The remaining coating, drying, rolling, and slitting steps are the same as in Embodiment 1.

[0076] Comparative Example 1 This embodiment provides a method for preparing a battery cell, which differs from Embodiment 1 only in that the mass ratio of LiFePO4, lithium replenishment material, acetylene black, and polyvinylidene fluoride is 96.8:0.4:1:1.8.

[0077] Comparative Example 2 This embodiment provides a method for preparing a battery cell, which differs from Embodiment 1 only in that the mass ratio of LiFePO4, lithium replenishment material, acetylene black, and polyvinylidene fluoride is 92.2:5:1:1.8.

[0078] Comparative Example 3 This comparative example provides a method for preparing a single battery cell, which differs from Example 1 only in that: No lithium-supplementing material is added to the positive electrode. The positive electrode formulation is: LiFePO4, acetylene black, and polyvinylidene fluoride mixed in a mass ratio of 97.2:1:1.8 (after removing the lithium-supplementing material, the total amount of positive electrode active material is kept similar to that in Example 1). The remaining steps are the same as in Example 1.

[0079] Table 1

[0080] The performance parameters of each embodiment and comparative example in Table 1 are analyzed from four aspects below: 1. The impact of lithium supplementation materials and dosage A comparison of the performance data from Examples 1-4 with Comparative Example 3 shows that adding an appropriate amount of lithium replenishing material (Li2MoO4@Te, Li2MoO4@Se, or Li5AlO4@S) to the positive electrode slurry can significantly improve the initial coulombic efficiency and cycle stability of the battery. Compared to Comparative Example 3 (without lithium replenishing material), its initial coulombic efficiency was only 87.2%, and its capacity retention after 500 cycles was 72.3%. In contrast, Example 1 (with 1.2 parts of lithium replenishing material) achieved an initial coulombic efficiency of 97.7% and a capacity retention of 92.5%. This is because the lithium replenishing material can provide an additional lithium source during the formation stage, compensating for the active lithium consumed in the formation of the solid electrolyte interphase (SEI) on the negative electrode surface. Simultaneously, the dissolution-redeposition process of Te, Se, or S species can regulate the composition and structure of the SEI, forming a more stable interfacial film with higher ionic conductivity.

[0081] Comparing Comparative Example 1 (0.4 parts), Comparative Example 2 (5 parts), and Example 1 (1.2 parts) with different amounts of lithium replenishment material, it can be seen that there is an optimal range for lithium replenishment amount. Due to insufficient lithium replenishment, Comparative Example 1 had lower initial discharge specific capacity (148.7 mAh / g) and initial coulombic efficiency (94.5%) than Example 1. While Comparative Example 2 had the highest initial charge specific capacity (163.5 mAh / g), its initial discharge specific capacity was only 150.2 mAh / g, its initial coulombic efficiency dropped to 91.9%, and its capacity retention rate after 500 cycles was only 78.5%. This indicates that excessive lithium replenishment material may lead to excessive residual inactive components in the positive electrode, or excessive dissolution of Te species during the formation process, forming an excessively thick or highly impedance interface layer on the negative electrode surface, which in turn deteriorates the cycle performance. Example 2 (1.0 part of lithium replenishment) had similar performance to Example 1, further verifying that 1.0 to 1.2 parts is the optimal range.

[0082] 2. Comparison of different lithium replenishment materials (Te, Se, S coating) Examples 1 (Li2MoO4@Te), 3 (Li2MoO4@Se), and 4 (Li5AlO4@S) used Te, Se, and S as surface modification or doping elements, respectively. The performance order was: Te (initial discharge specific capacity 158.5 mAh / g, initial coulombic efficiency 97.7%, 500-cycle capacity retention 92.5%) > Se (initial discharge specific capacity 157.4 mAh / g, initial coulombic efficiency 97.5%, 500-cycle capacity retention 91.2%) > S (initial discharge specific capacity 155.0 mAh / g, initial coulombic efficiency 97.4%, 500-cycle capacity retention 90.5%). The possible reason is that Te has high electronic conductivity and a moderate dissolution potential, allowing it to partially dissolve and diffuse controllably to the negative electrode during formation. After reduction, it catalyzes the polymerization reaction of EC / FEC, forming a tough SEI film rich in organic polymers. Se exhibits similar chemical behavior but slightly higher reactivity, potentially leading to slightly faster dissolution-deposition kinetics and slightly poorer interfacial uniformity. While S can participate in interfacial film formation, its intermediate products (polysulfides) in the electrolyte are prone to shuttle, potentially causing side reactions, thus resulting in slightly inferior performance. Furthermore, the difference between the matrix materials Li₂MoO₄ and Li₅AlO₄ may also affect lithium-ion release kinetics, but the results of this study show that the choice of coating element has a more significant impact on performance.

[0083] 3. Influence of negative electrode material Example 5 used a silicon-carbon composite material (containing 10 wt% SiO) to replace the graphite anode, and was paired with the same cathode lithium replenishment formulation as Example 1. The results showed that the initial charge specific capacity was as high as 178.6 mAh / g (higher than 162.3 mAh / g in Example 1), attributed to the higher lithium storage capacity of the silicon-based material. However, its initial discharge specific capacity was only 163.2 mAh / g, the initial coulombic efficiency dropped to 91.4%, and the capacity retention rate after 500 cycles was 85.3%, all lower than that of the graphite system in Example 1. This is because the silicon-based anode undergoes severe volume expansion during the initial lithiation process, and the SEI formation consumes more active lithium. Simultaneously, volume changes during cycling lead to repeated interface rupture and regeneration, accelerating capacity decay. Although the cathode lithium replenishment material provided an additional lithium source, the compensation was still insufficient to fully match the high irreversible capacity of the silicon-based anode. These results suggest that for high-capacity anode systems, further optimization of the type and amount of lithium replenishment material or the introduction of a pre-lithiation step is needed.

[0084] 4. The comprehensive mechanism of action of lithium supplementation materials Based on the above results, the designed lithium supplementation material (such as Li2MO4@Te) plays a dual role in the battery: Chemical lithium replenishment: During the first charge, Li₂MoO₄ decomposes to release active Li. + This compensates for lithium loss caused by the formation of the negative electrode SEI, thereby improving the first coulombic efficiency (from 87.2% to 97.7%, compared to Example 1 and Comparative Example 3).

[0085] Interfacial catalytic film formation: During the formation stage (low current charging to 3.6V~3.8V and constant voltage), Te (or Se, S) species partially dissolve and migrate to the negative electrode surface. After reduction, they catalyze the reduction polymerization of solvents such as EC / FEC to form a stable SEI film rich in organic polymers. This film has good flexibility, high ionic conductivity, and can adapt to volume changes during charge and discharge, thus significantly improving long-cycle stability (retention rate increased from 72.3% to 92.5% after 500 cycles).

[0086] In contrast, Comparative Example 1, due to insufficient lithium replenishment, could not fully compensate for lithium loss and had limited interface modification effect; Comparative Example 2, due to excessive lithium replenishment, may lead to an excess of Te species, forming an excessively thick or uneven interface layer on the negative electrode, increasing polarization and accelerating capacity decay.

[0087] This application demonstrates that adding an appropriate amount (approximately 1.0%~1.2% by mass) of lithium replenishment material to the lithium iron phosphate cathode, combined with a specific formation process (pre-charging to 3.6V~3.8V with a small current and maintaining constant voltage), can simultaneously achieve efficient lithium replenishment and interface regulation, increasing the initial coulombic efficiency of the graphite anode system to 97.7% and the capacity retention rate after 500 cycles to 92.5%. Te shows better performance than Se and S. For high-capacity anodes such as silicon-carbon, this lithium replenishment strategy remains effective, but further optimization of the lithium replenishment amount or combination with other pre-lithiation technologies is needed. This application provides a feasible material and process solution for developing high initial efficiency and long lifespan lithium-ion batteries.

[0088] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A battery cell, characterized in that, include: A battery cell assembly, the battery cell assembly comprising a negative electrode, a separator and a positive electrode stacked together; The housing, in which the battery cell assembly is located; Electrolyte, wherein the electrolyte is located within the housing; The positive electrode includes a lithium replenishing material, the molecular formula of which is Li. x MO4@A, where M is Mo or Al, A is S, Se or Te, and x=2 or 5.

2. The battery cell according to claim 1, characterized in that, The positive electrode sheet also includes a positive electrode active material, a conductive agent, and a binder, and the amount of the lithium replenishing material is 0.5% to 5% of the total mass of the positive electrode active material, the lithium replenishing material, the conductive agent, and the binder.

3. The battery cell according to claim 1 or 2, characterized in that, The positive electrode active material includes at least one of LiFePO4, LiNiO2, and LiCoO2.

4. A method for preparing a battery cell as described in any one of claims 1 to 3, characterized in that, include: A battery cell assembly is provided, the battery cell assembly comprising a negative electrode, a separator and a positive electrode stacked together; A housing is provided to house the battery cell assembly within the housing; Provide electrolyte and inject the electrolyte into the housing; A formation process is performed to obtain battery cells; The positive electrode includes a lithium replenishing material, the molecular formula of which is Li. x MO4@A, where M is Mo or Al, A is S, Se or Te, and x=2 or 5.

5. The method for preparing a single battery cell according to claim 4, characterized in that, The method for preparing the lithium supplementation material includes: The lithium source and the M source are dissolved in a solvent to form a sol; Nanoparticles of element A are added to the sol, dispersed, dried, and calcined in an inert atmosphere to obtain the lithium supplement material. The M source is an aluminum source or a molybdenum source.

6. The method for preparing a battery cell according to claim 5, characterized in that, The lithium source includes lithium acetate.

7. The method for preparing a battery cell according to claim 5, characterized in that, The molybdenum source includes ammonium molybdate, and the aluminum source includes at least one of aluminum nitrate, aluminum isopropoxide, aluminum chloride, and aluminum sulfate.

8. The method for preparing a battery cell according to claim 5, characterized in that, The calcination temperature is 300℃~600℃.

9. A battery device, characterized in that, The battery device includes a battery cell as described in any one of claims 1 to 3, or a battery cell obtained by the preparation method as described in any one of claims 4 to 8, and the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

10. An energy storage device, characterized in that, The energy storage device includes the battery device as described in claim 9, the battery device being used to store electrical energy.

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