A cathode active material for a lithium metal battery, a preparation method thereof, and an application thereof

Abstract

The present invention discloses a positive electrode active material for lithium metal batteries, and its preparation method and application. The positive electrode active material includes a basic active material, an energy-replenishing active material, and an energy-limiting material. The energy-limiting material is applied by combining chemistry and physics. On the basis of improving the microstructure and apparent morphology of the basic active material and the energy-replenishing active material, a composite hybrid is performed to form a multi-state composite active material based on the basic active material, effectively breaking through the inherent defects of the active material and the battery prepared therefrom, and realizing the energy limitation of the positive electrode active material of the electrochemical system. Then, a conductive agent and a positive electrode binding material are added, and after coating or rolling on the positive electrode current collector, it is successfully applied to the development and production of the positive electrode of a wide-temperature, high-energy lithium metal primary battery. The positive electrode active material of the present invention is applied to lithium metal primary batteries and reserve batteries, maximizing the coulombic efficiency of the battery positive electrode, and is suitable for mass production and application.

Description

Technical Field

[0001] The present invention is based on a lithium fluoride carbon electrochemical system and belongs to the technical field of primary batteries. It particularly relates to a metal lithium battery positive electrode active material, a preparation method and application thereof, and a metal lithium battery using the positive electrode sheet. Background Art

[0002] Lithium carbon fluoride batteries are the electrochemical system batteries with the highest mass-to-energy ratio today (theoretically 2180Wh / kg). They not only achieve battery miniaturization and lightweighting, but also have the advantages of high safety and long storage life (>10 years). They can meet the needs of high-end civilian and military power supplies and have extremely high application value.

[0003] Carbon fluoride active materials suffer from inherent drawbacks such as voltage hysteresis, low discharge potential, severe discharge polarization, and the mutual restriction of specific energy and rate performance (the "low faradaic charge" phenomenon). These drawbacks have severely hampered the development and application of these materials, limiting their use to instrumentation and electronic equipment with medium and low discharge rates, or medical implantable power supplies. Breaking through the high-current discharge performance of lithium carbon fluoride batteries and enabling their application in high-energy, high-power applications has been a persistent research priority both domestically and internationally.

[0004] In order to improve the electrochemical performance, domestic researchers have used various methods to fluorinate various nano-scale carbon materials such as carbon nanofibers, carbon nanotubes, fullerenes and ordered mesoporous carbon, or adopted other methods such as polypyrrole coating, elemental sulfur coating, metal and oxide coating, carbon heat treatment and graphene / SVO ball milling to modify the fluorinated carbon active material. However, the rate enhancement capability is still limited, and is either achieved with extremely low discharge efficiency and discharge platform, or compensated by increasing the capacity of the battery (simultaneous increase in volume and mass).

[0005] Chinese invention patent application CN108054404A discloses a novel lithium / carbon fluoride battery. This battery utilizes a novel carbon fluoride material, Ketjen black fluoride, as the positive electrode material. The excellent electrical conductivity of Ketjen black fluoride reduces the internal resistance of the battery during operation, thereby increasing the operating voltage and energy density. This application, considered a new carbon fluoride material, has the potential to improve the battery's discharge capacity, reportedly reaching a high-rate discharge of 0.5C.

[0006] Chinese invention patent application publication number CN109216698A discloses a method for preparing fluorinated nanographite, a positive electrode material for lithium-carbon fluoride batteries. The method uses a magnetic stirring milling method to prepare nanographite as a precursor. Using a direct fluorination method, fluorine gas and nanographite react at high temperature to form an intercalation compound of carbon and fluorine to obtain the fluorinated nanographite material. This method is considered a novel fluorinated carbon material for research and application, and has the potential to improve the battery's voltage platform, specific capacity, and hysteresis voltage.

[0007] The Chinese invention patent application with publication number CN105680047B discloses a nano-semiconductor modified lithium-carbon fluoride battery positive electrode material, a cylindrical battery and its preparation method. Nano-semiconductors are used to improve the conductivity of the fluorinated graphite-based positive electrode material by grinding and modification. At the same time, the fiberization process is optimized and combined with the rolling process to obtain a better density state, thereby improving the problems of poor battery power and low-temperature discharge performance of lithium-carbon fluoride batteries. It can improve the discharge capacity of batteries below 0.5C. The Chinese invention patent application with publication number CN108565430A discloses a method for preparing a high-energy-density primary battery positive electrode material. Carbon fluoride powder and elemental nano-sulfur powder are ground, and solvent CS2 is added and continued to grind, and then heat treated to obtain a fluorinated carbon-sulfur composite positive electrode material. Although it is shown that the carbon fluoride-sulfur primary battery can achieve a discharge specific capacity of 833.9 mAh / g under constant current discharge (100 mAh / g) at a cut-off voltage of 1.5 V, based on the 190 mAh capacity of its button BR2032 battery, it is only 0.53C, and CS2 is harmful to the human body and the environment.

[0008] Chinese invention patent application publication number CN110380013A discloses a cathode material for ultra-high power density lithium-carbon fluoride batteries, as well as its preparation method and application. The material is improved by mixing fluorinated graphene with a fluorine content of 48-54% by weight (a medium- to high-fluorine-content carbon fluoride), one or more of fluorinated graphite, fluorinated carbon nanotubes, fluorinated carbon black, and fluorinated carbon fibers, with a two-step mixing method using a conductive agent. This material is a mixture of substances with different characteristics within the same electrochemical system, and while the discharge current density reaches 40 A / g, the voltage-specific capacity curve does not reflect the discharge efficiency.

[0009] Chinese invention patent application publication number CN109546105B discloses a power-type lithium fluoride carbon battery and its manufacturing method. The delithiated material, obtained by heating a lithium-rich manganese-based, high-nickel ternary, or lithium nickel manganese oxide in H₂SO₄, is then ball-milled and sintered at high temperature to produce a high-voltage material-modified carbon fluoride. While this method improves the battery's power performance, the commercial product only has a charge / discharge rate of approximately 0.7C. Furthermore, relying solely on high-voltage material modification increases the battery's self-discharge, which in turn affects its performance.

[0010] To date, the lithium fluoride carbon active materials and batteries prepared therefrom reported in domestic patents, except for theoretical design and laboratory test data, have not yet achieved a discharge rate exceeding 0.7C (1C = battery nominal capacity) while maintaining high capacity (or high energy density), and the theoretical design and laboratory test data are based on a single aspect of the active material, rather than on the battery product. In summary, with a view to fully realizing the development and production of high-end metal lithium batteries, it is indeed necessary to develop a new active material with sustained high-rate discharge performance without reducing energy density, so as to overcome the inherent defects of carbon fluoride active materials, comprehensively improve battery performance, meet the needs of batteries in high-tech fields, and at the same time enable large-scale and stable production of metal lithium battery positive electrodes. Summary of the Invention

[0011] The purpose of the present invention is to design and process a multi-state active material based on the actual design, manufacture and application of batteries, targeting the inherent defects of existing fluorinated carbon active materials, in accordance with the design ideas and principles of filling in the gaps and increasing activity, with a basic active material as the matrix and an energy-supplementing active material as the supplement, to achieve the energy and performance limit of the positive electrode active material (also known as the maximization of both energy and performance), and facilitate large-scale production.

[0012] Another object of the present invention is to provide a lithium metal positive electrode to improve the comprehensive electrical performance of metal lithium batteries.

[0013] The present invention also relates to the use of the multi-state active material as a positive electrode of a lithium metal battery in a lithium metal battery.

[0014] In order to overcome the inherent defects and bottleneck problems of lithium fluoride carbon electrochemical system batteries, the present invention designs and adopts the following technical solutions to achieve the purpose of the invention.

[0015] On one hand, the present invention provides a positive electrode active material for a metal lithium battery, characterized in that the composition of the positive electrode active material for a metal lithium battery is as follows: 65% to 90% of a fluorinated carbon positive electrode basic active material, 5% to 30% of an energy replenishing active material, and 5% to 20% of an energy limiting material.

[0016] The basic active material is a fluorinated carbon positive electrode basic active material; the energy replenishing active material includes but is not limited to MnO2, Li(NiCoMn)O2 and Ag2V4O 11 At least one of the energy-limiting materials includes but is not limited to at least one of NaOH, KOH, AgOH, (NH4)2S2O8, Na2S2O8 and K2S2O8.

[0017] Preferably, the composition of the positive electrode active material of the metal lithium battery is as follows: 70% to 80% of the fluorinated carbon positive electrode basic active material, 10% to 20% of the energy replenishing active material, and 10% to 15% of the energy limiting material;

[0018] Preferably, the basic active material includes but is not limited to any one of fluorinated graphite with an F content of 54.27 wt% to 65 wt%, fluorinated Ketjen black, fluorinated carbon fiber, fluorinated carbon nanotube, and fluorinated graphene.

[0019] Another aspect of the present invention provides a method for preparing the above-mentioned positive electrode active material for a lithium metal battery, which is characterized by comprising the following specific steps:

[0020] Step 1: Select the basic active material: Based on the battery's special performance technical indicators, comprehensively design and analyze the battery's volumetric energy and mass energy, and on the basis of determining the battery's electrochemical system, select the basic active material for the electrochemical system;

[0021] Preferably, the basic active material includes but is not limited to any one of fluorinated carbon positive electrode active materials such as fluorinated graphite with an F content of 54.27 wt% to 65 wt%, fluorinated Ketjen black, fluorinated carbon fiber, fluorinated carbon nanotube, fluorinated graphene, etc.

[0022] Step 2: Selecting the energy-replenishing active material: Analyze the discharge hysteresis voltage, discharge platform voltage, and inherent defects of the basic active material selected in step 1. Design, select, or process the energy-replenishing active material based on the battery volumetric energy and mass specific energy design.

[0023] Furthermore, the energy-replenishing active materials are divided into pressure-boosting active materials and polarization internal resistance-reducing active materials. The pressure-boosting active materials are selected to have a standard voltage difference of 0V to 0.5V compared to the standard voltage of the base active material selected in step 1 of the present invention, based on the considerations of filling the hysteresis voltage trough, increasing the initial discharge voltage, or both. The polarization internal resistance-reducing active materials are selected to have an electrochemical reaction product that increases the positive electrode conductivity during battery operation or adsorbs the electrochemical reaction products of the base active material.

[0024] Preferably, the energy replenishing active materials include but are not limited to MnO2, Li(NiCoMn)O2 and Ag2V4O in other electrochemical systems. 11 At least one active substance.

[0025] Furthermore, the Ag2V4O 11 The compound is synthesized from one of Ag2CO3 and Ag2O and one of NH4VO3 and V2O5 in a protective atmosphere by a hydrothermal treatment method and a rheological phase reaction method in steps.

[0026] Step 3: Improving the basic active material and the energy-replenishing active material: Analyze the impact of the microstructure and surface morphology of the basic active material and the energy-replenishing active material on their electrical properties, as well as the coordination and adaptability of the energy-replenishing active material and the basic active material to the standard voltage. Select corresponding energy-limiting materials and use hydrothermal treatment and redox methods to improve the basic active material and the energy-replenishing active material.

[0027] Preferably, the energy-limiting material includes but is not limited to at least one of NaOH, KOH, AgOH, (NH4)2S2O8, Na2S2O8 and K2S2O8.

[0028] Step 4, preparing a multi-state composite hybrid metal lithium battery positive electrode active material: the improved basic active material prepared in step 3 is composite-hybridized with the energy replenishing active material to obtain a multi-state composite hybrid metal lithium battery positive electrode active material, thereby achieving energy limit of the active material.

[0029] Preferably, the basic active substance accounts for 70% to 90% of the total active substance, and the energy-replenishing active substance accounts for 10% to 30% of the total active substance.

[0030] Preferably, the composite hybridization method in step 4 includes at least one of a rheological phase reaction method, a chemical reduction method, a mechanical ball milling method, and a high-temperature sintering method.

[0031] Preferably, in step 4, for the composite of the energy-replenishing active substance containing a metal Ag ion compound and the basic active substance, wet ball milling is first performed, and then the mixture is placed in a polytetrafluoroethylene tank, and hybrid composite is performed by chemical reduction and rheological phase reaction method; for the composite of at least one energy-replenishing active substance containing a metal ion compound such as MnO2, Li(NiCoMn)O2 and the basic active substance, dry ball milling is first performed, and then the mixture is placed in a stainless steel container, and high-temperature sintering is performed for hybrid composite.

[0032] Another aspect of the present invention further provides a use of the above-mentioned metal lithium battery positive electrode active material, characterized in that the metal lithium battery positive electrode active material is used to prepare a lithium metal battery positive electrode sheet.

[0033] Preferably, the method for preparing a battery positive electrode sheet using the metal lithium battery positive electrode active material is as follows: the multi-state composite hybrid metal lithium battery positive electrode active material is stirred and dispersed with a conductive agent, a binder, and a solvent to form a material mass or slurry, which is then rolled or coated on a current collector to form a battery positive electrode sheet, which is then assembled into a battery.

[0034] Preferably, the battery is assembled, and the prepared battery positive electrode sheet, metal lithium negative electrode sheet and separator are processed in a stacking or winding manner, and the electrolyte is injected to make button-type, cylindrical, soft-pack or special-shaped metal lithium primary batteries and reserve batteries.

[0035] In summary, the positive electrode active material energy limit method and application according to the embodiments of the present invention can achieve the following beneficial effects:

[0036] 1. The study proposes design ideas and principles for filling in the gaps and increasing activity. By combining chemistry and physics and applying energy-limiting materials, the basic active substances and energy-replenishing active substances are improved from the two directions of microstructure and surface morphology. On the basis of maximizing the electrical properties of the basic active substances and energy-replenishing active substances, composite hybridization is carried out to effectively solve the inherent defects of fluorinated carbon positive electrode active substances, improve the positive electrode resistance and power transmission efficiency of lithium metal batteries, optimize and enhance the comprehensive electrical performance of lithium batteries, and especially make it possible to develop and manufacture high-end batteries (a wide-temperature, high-energy metal lithium battery).

[0037] 2. Based on the volumetric energy and mass specific energy of the battery, as well as the coordinated adaptability of active materials in different electrochemical systems, the combination of basic active materials and energy-supplementing active materials was formulated and implemented, maximizing the comprehensive performance of batteries of the same electrochemical system and specifications, especially achieving sustained high-rate discharge performance with slightly or no reduction in energy density.

[0038] 3. Based on the actual design and manufacturing of the battery, the materials, instruments and equipment involved in the implementation of the present invention are all commercial products, which facilitates the large-scale production of metal lithium batteries with positive electrode active materials and fluorinated carbon electrochemical systems.

[0039] 4. The present invention can theoretically achieve a discharge rate of 5C to 20C, with the specific energy of the positive electrode active material of the multi-state composite hybrid metal lithium battery greater than 700mAh / g (cut-off voltage 1.5V) and the discharge efficiency greater than 87% (0.025C). This is affected by the understanding of the microstructure of the active material, process control, and raw material prices. Although the design, manufacture, and testing of 4C and 5C batteries have been achieved and have met expectations, further practice is needed, especially the manufacturing process control needs to be continuously optimized and improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the preparation process of the multi-state composite hybrid metal lithium battery positive electrode active material of the present invention.

[0041] Figure 2 This is a discharge curve diagram of a fluorinated carbon-based metal lithium battery prepared from the multi-state composite hybrid metal lithium battery positive electrode active material of the present invention. DETAILED DESCRIPTION

[0042] To further illustrate the above and other objects, features, and beneficial effects of the present invention, a specific embodiment of a wide-temperature, high-energy 653665 lithium primary battery positive electrode is described in detail below. However, the embodiments of the present invention are not limited thereto. In other words, the specific examples described below are merely illustrative of the present invention and are not intended to limit the present invention. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer shall prevail.

[0043] In one aspect, the present invention provides a positive electrode active material for a lithium metal battery. The positive electrode active material for a lithium metal battery comprises: 65% to 90% of a fluorinated carbon positive electrode base active material, 5% to 30% of an energy-replenishing active material, and 5% to 20% of an energy-limiting material. Preferably, the fluorinated carbon positive electrode base active material comprises 70% to 80%, the energy-replenishing active material comprises 10% to 20%, and the energy-limiting material comprises 10% to 15%.

[0044] The basic active material is a fluorinated carbon positive electrode basic active material; the energy replenishing active material includes but is not limited to MnO2, Li(NiCoMn)O2 and Ag2V4O 11 At least one of the energy-limiting materials includes but is not limited to at least one of NaOH, KOH, AgOH, (NH4)2S2O8, Na2S2O8 and K2S2O8.

[0045] The basic active material includes but is not limited to any one of fluorinated graphite with an F content of 54.27 wt% to 65 wt%, fluorinated Ketjen black, fluorinated carbon fiber, fluorinated carbon nanotube, and fluorinated graphene.

[0046] Another aspect of the present invention provides a method for preparing the above-mentioned positive electrode active material for a lithium metal battery, the specific steps of which are as follows:

[0047] Step 1, selecting a basic active material: Based on the technical indicators of the battery's special performance, comprehensively design and analyze the volume specific energy and mass specific energy of the battery, and on the basis of determining the battery's electrochemical system, select the basic active material for the electrochemical system; preferably, the basic active material includes but is not limited to any one of fluorinated carbon positive electrode active materials such as fluorinated graphite, fluorinated Ketjen black, fluorinated carbon fiber, fluorinated carbon nanotubes, fluorinated graphene, etc., with a F content of 54.27wt% to 65wt%.

[0048] Step 2, select the energy replenishing active material: for the basic active material selected in step 1, analyze its discharge hysteresis voltage, discharge platform voltage and inherent defects, and design or process the energy replenishing active material according to the volume energy ratio and mass energy ratio of the battery; preferably, the energy replenishing active material is divided into a boosting active material and a polarization internal resistance reducing active material. Among them, the boosting active material is selected from the analysis of filling the hysteresis voltage trough or increasing the initial discharge voltage or both, and the difference between its standard voltage and the standard voltage of the basic active material selected in step 1 of the present invention is 0V to 0.5V; the polarization internal resistance reducing active material is selected, and its electrochemical reaction product can increase the positive electrode conductivity during battery operation or adsorb the electrochemical reaction product of the basic active material. Preferably, the energy replenishing active material includes but is not limited to MnO2, Li(NiCoMn)O2 and Ag2V4O in other electrochemical systems. 11 Preferably, the Ag2V4O 11 The compound is synthesized from one of Ag2CO3 and Ag2O and one of NH4VO3 and V2O5 in a protective atmosphere by a hydrothermal treatment method and a rheological phase reaction method in steps.

[0049] Step 3, improving the basic active substance and the energy-replenishing active substance: analyzing the influence of the microstructure and surface morphology of the basic active substance and the energy-replenishing active substance on the electrical properties, as well as the coordinated adaptability of the energy-replenishing active substance and the standard voltage of the basic active substance, selecting corresponding energy-limiting materials, and using hydrothermal treatment and redox methods to improve the basic active substance and the energy-replenishing active substance; preferably, the energy-limiting material includes but is not limited to at least one of NaOH, KOH, AgOH, (NH4)2S2O8, Na2S2O8 and K2S2O8.

[0050] Step 4: Preparing a multi-element composite hybrid metal lithium battery positive electrode active material: The improved base active material prepared in Step 3 is composite-hybridized with an energy-replenishing active material to produce a multi-element composite hybrid metal lithium battery positive electrode active material, achieving energy-limited active material. Preferably, the base active material accounts for 70% to 90% of the total active material, and the energy-replenishing active material accounts for 10% to 30% of the total active material. Preferably, the composite-hybridization method in Step 4 includes at least one of rheological phase reaction, chemical reduction, mechanical ball milling, and high-temperature sintering. Preferably, in Step 4, for composite-hybridization of the energy-replenishing active material containing a metal Ag ion compound with the base active material, wet ball milling is first performed, followed by placement in a polytetrafluoroethylene container and composite-hybridization performed using chemical reduction and rheological phase reaction. For composite-hybridization of at least one energy-replenishing active material containing a metal ion compound, such as MnO2 or Li(NiCoMn)O2, with the base active material, dry ball milling is first performed, followed by placement in a stainless steel container and composite-hybridization performed using high-temperature sintering.

[0051] Another aspect of the present invention further provides a use of the above-mentioned metal lithium battery positive electrode active material, characterized in that the metal lithium battery positive electrode active material is used to prepare a lithium metal battery positive electrode sheet.

[0052] Preferably, the method for preparing a battery positive electrode sheet using the metal lithium battery positive electrode active material is as follows: the multi-state composite hybrid metal lithium battery positive electrode active material is stirred and dispersed with a conductive agent, a binder, and a solvent to form a material mass or slurry, which is then rolled or coated on a current collector to form a battery positive electrode sheet, which is then assembled into a battery.

[0053] Preferably, the battery is assembled, and the prepared battery positive electrode sheet, metal lithium negative electrode sheet and separator are processed in a stacking or winding manner, and the electrolyte is injected to make button-type, cylindrical, soft-pack or special-shaped metal lithium primary batteries and reserve batteries.

[0054] The embodiments of the present invention are as follows:

[0055] Example (see attached Figure 1 )

[0056] In the first step, according to the technical indicators of battery special performance, the volume energy of the battery is 230Ah / L and the mass energy is 1.75Ah / g, and fluorinated graphite microspheres with an F content of 60% (wt) are selected as the basic active material.

[0057] In the second step, MnO2, Li(NiCoMn)O2 and Ag2V4O were selected based on the device operating voltage (>2.2V) and operating current (constant current 13A). 11 At least one of the active substances is used as an energy replenishing active substance.

[0058] In the third step, KOH is selected as the energy-limiting material of the basic active substance. 1 part of KOH, 45 parts of fluorinated graphite microspheres and 100 parts of alcohol (concentration 50%) are taken in a mass ratio, dispersed and stirred, and then subjected to hydrothermal treatment, cooling, cleaning and drying to obtain polarized fluorinated graphite microspheres.

[0059] In the third step, K2S2O8 is selected as the energy-limiting material of the energy-replenishing active substance. 1 part of K2S2O8, 1.68 parts of Li(NiCoMn)O2 and 3.1 parts of deionized water are taken in a mass ratio, dispersed and stirred, and then washed and dried to obtain a polarized energy-replenishing active substance.

[0060] In the third step, 10 parts of polarized fluorinated graphite microspheres, 0.87 parts of Ag2CO3, 1.48 parts of NH4VO3 and 4.5 parts of deionized water are weighed according to the mass ratio, and after wet ball milling or grinding, they are compounded step by step by hydrothermal treatment and rheological phase reaction method in a protective atmosphere, cleaned and dried to obtain a binary active material.

[0061] In the fourth step, 94 parts of binary active material and 6 parts of polarized energy replenishing active material are weighed according to the mass ratio, placed in a dispersion stirring barrel, and dispersed and stirred at high speed for 8h to 12h to obtain a multi-state composite hybrid metal lithium battery positive electrode active material.

[0062] The fifth step is to stir and disperse the multi-state composite hybrid metal lithium battery positive electrode active material with a conductive agent, a binder, and a solvent to form a material mass or slurry, and then roll or apply it to a current collector to form a battery positive electrode sheet.

[0063] The present invention further carried out 6 groups of examples (Examples 1 to 5) and 2 groups of comparative examples (Comparative Examples 1 to 2). The material composition of the positive electrode sheets of each example and comparative example is shown in Table 1:

[0064] Table 1 Material composition of positive electrode

[0065] Types of positive electrode active materials for lithium metal batteries Active ingredient ratio Example 1 Polarized graphite fluoride microspheres 1 Comparative Example 1 Graphite fluoride microspheres 1 Example 2 <![CDATA[Polarized fluorinated graphite microspheres + MnO2]]> 4:1 Example 3 <![CDATA[Polarized fluorinated graphite microspheres + Li(NiCoMn)O2]]> 4:1 Example 4 <![CDATA[Polarized fluorinated graphite microspheres + Ag2V4O 11 > 4:1 Example 5 <![CDATA[Polarized fluorinated graphite microspheres + Ag2V4O 11 + Li(NiCoMn)O2]]> 4:0.5:0.5 Comparative Example 2 <![CDATA[Graphite fluoride microspheres + Ag2V4O 11 + Li(NiCoMn)O2]]> 4:0.5:0.5

[0066] The present invention respectively uses the positive electrode sheets prepared in Examples 1 to 5 and Comparative Examples 1 to 2 above, with metallic lithium as the negative electrode, a PEP diaphragm, and 1 mol / L lithium perchlorate / propylene carbonate + ethylene glycol dimethyl ether (volume ratio 1:1) as the electrolyte. 513666 (10 batteries per example), 2.5Ah batteries are assembled in a glove box with a dew point below -30°. The open circuit voltage (V), static internal resistance (Ω), and maximum constant current discharge performance (rate and discharge efficiency at 1.0V cutoff) of the battery are tested. The test results are shown in Table 2.

[0067] Table 2 Electrical performance test

[0068]

[0069] From the data of Examples 1 to 4 in Table 2, it can be seen that the positive electrode sheet prepared by adopting the technical solution of the multi-state composite hybrid metal lithium battery positive electrode active material of the present invention can effectively reduce the static internal resistance of the battery and significantly improve the battery discharge rate and efficiency.

[0070] The embodiments described above are only part of the embodiments of the present invention, but not all of the embodiments.

[0071] Based on the disclosure and explanation of the above description, those skilled in the art to which the present invention belongs can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above. Any obvious improvements, substitutions or modifications made by those skilled in the art on the basis of the present invention fall within the scope of protection of the present invention, including but not limited to the widest scope consistent with the principles and novel features disclosed herein. In addition, although some specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for preparing a positive electrode active material for a metal lithium battery, characterized in that: The composition of the positive electrode active material of the metal lithium battery is as follows: the mass percentage of the carbon fluoride positive electrode basic active material is 65% to 90%, the mass percentage of the energy replenishing active material is 5% to 30%, and the mass percentage of the energy limiting material is 5% to 20%. The specific steps of the preparation method are as follows: Step 1: Selecting a basic active material: The basic active material is a fluorinated carbon-based positive electrode basic active material; the fluorinated carbon-based positive electrode basic active material includes any one of fluorinated graphite, fluorinated Ketjen black, fluorinated carbon fiber, fluorinated carbon nanotube, and fluorinated graphene; the F content in the fluorinated carbon-based positive electrode basic active material is 54.27 wt% to 65 wt%; Step 2: Selecting active energy replenishing substances: The active energy replenishing substances include MnO2, Li(NiCoMn)O2 and Ag2V4O 11 At least one of the following; Step 3, respectively improving the basic active substance and the energy-replenishing active substance: selecting a corresponding energy-limiting material, and using a hydrothermal treatment method to improve the basic active substance to obtain an improved basic active substance; selecting a corresponding energy-limiting material to improve the energy-replenishing active substance to obtain an improved energy-replenishing active substance; the energy-limiting material includes at least one of NaOH, KOH, AgOH, (NH4)2S2O8, Na2S2O8, and K2S2O8; Step 4, preparing a multi-state composite hybrid metal lithium battery positive electrode active material: the improved basic active material prepared in step 3 is composite-hybridized with the improved energy-replenishing active material to obtain a multi-state composite hybrid metal lithium battery positive electrode active material, thereby achieving energy limit of the active material.

2. The method for preparing a positive electrode active material for a lithium metal battery according to claim 1, wherein: The composition of the metal lithium battery positive electrode active material is as follows: the mass percentage of the carbon fluoride positive electrode basic active material is 70% to 80%, the mass percentage of the energy replenishing active material is 10% to 20%, and the mass percentage of the energy limiting material is 10% to 15%.

3. The method for preparing a positive electrode active material for a lithium metal battery according to claim 1, wherein: The basic active material accounts for 80% to 100% of the total mass of the positive electrode active material, and the energy supplement active material accounts for 10% to 30% of the total mass of the positive electrode active material.

4. The method for preparing a positive electrode active material for a lithium metal battery according to claim 1, wherein: The composite hybridization method in step 4 includes at least one of a rheological phase reaction method, a chemical reduction method, a mechanical ball milling method, and a high-temperature sintering method.

5. The method for preparing a positive electrode active material for a lithium metal battery according to claim 1 or 4, wherein: In the step 4, for the composite of the energy-replenishing active substance containing a metal Ag ion compound and the basic active substance, wet ball milling is first performed, and then placed in a polytetrafluoroethylene tank, and hybrid composite is performed by chemical reduction and rheological phase reaction method; for the composite of at least one energy-replenishing active substance containing a metal ion compound of MnO2 and Li(NiCoMn)O2 and the basic active substance, dry ball milling is first performed, and then placed in a stainless steel container, and high-temperature sintering is performed for hybrid composite.

6. The method for preparing a positive electrode active material for a metal lithium battery according to claim 1, wherein: The lithium metal battery positive electrode active material is used to prepare lithium metal battery positive electrode plates.

7. The method for preparing a positive electrode active material for a lithium metal battery according to claim 1, wherein: The method for preparing a battery positive electrode sheet using the metal lithium battery positive electrode active material is as follows: the multi-state composite hybrid metal lithium battery positive electrode active material is stirred and dispersed with a conductive agent, a binder, and a solvent to form a material mass or slurry, which is then rolled or coated on a current collector to form a battery positive electrode sheet, which is then assembled into a battery.

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