Composite lithium supplement and preparation method thereof, and battery

Abstract

The application relates to a composite lithium supplementing agent, a preparation method thereof and a battery. The composite lithium supplementing agent comprises an organic lithium supplementing agent, a MOF and a Mxene, wherein the organic lithium supplementing agent comprises a compound with a general formula of Li2C n O n (n>=2) and / or a general formula of Li2C n O n+2 (n>=2); the MOF is synthesized by a transition metal element and a dicarboxylic acid ligand; the MOF and the Mxene undergo a complexing reaction to generate a complex with a three-dimensional structure; and the organic lithium supplementing agent is loaded on the complex. The composite lithium supplementing agent can effectively avoid the problem of battery performance degradation caused by gas generation of the organic lithium supplementing agent, and improves the cycle performance of the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a composite lithium replenishing agent, its preparation method, and a battery. Background Technology

[0002] Because of the formation of an SEI film during the first charge and discharge of the battery, lithium ions are irreversibly consumed, which leads to a decrease in battery capacity and a deterioration in cycle performance. Therefore, in order to improve the energy density of the battery, lithium replenishment materials are usually used to pre-replenish the battery with lithium.

[0003] Traditional lithium replenishment materials have two main problems: first, they require a high delithiation potential, meaning the battery needs to be charged to a high potential before decomposition, which places high demands on equipment and manufacturing processes; second, after delithiation, the replenishing agent leaves behind inactive substances with low conductivity inside the cell, affecting the overall conductivity of the electrodes. Since organic lithium replenishing agents have the advantage of leaving no residue compared to other replenishing agents, research on organic lithium replenishing agents has gradually shifted. However, current organic lithium replenishing agents still have the following drawbacks: high impedance, slow lithium ion delithiation, and a tendency to generate gases such as CO2 during decomposition, which can affect battery cycle life and high-temperature performance. Summary of the Invention

[0004] Based on this, and in response to the above problems, this application provides a composite lithium replenishing agent, its preparation method, and a battery to solve the aforementioned technical issues.

[0005] The first aspect of this application provides a composite lithium supplement agent, comprising an organic lithium supplement agent, a MOF, and Mxene, wherein the organic lithium supplement agent comprises a compound of the general formula Li2C. n O n (n≥2) and / or the general formula is Li2C n O n+2 Compounds with n≥2;

[0006] MOFs are synthesized from transition metal elements and dicarboxylic acid ligands;

[0007] MOF and Mxene undergo a complexation reaction to generate a complex with a three-dimensional structure;

[0008] Organic lithium supplements are loaded onto complexes.

[0009] In some embodiments, the mass ratio of the organic lithium supplement, Mxene, and MOF is 1:(1.5~2):(1.5~2.2).

[0010] In some implementations, Li2C n O n(n≥2) are cyclic, including at least one of compounds with structures of formulas (I) to (IV).

[0011] , , , .

[0012] In some implementations, Li2C n O n+2 (n≥2) are chain-like, including at least one of compounds with structures of formulas (V) to (VII).

[0013] , , .

[0014] In some embodiments, the MOF includes one or more of MIL-53Cr, MIL-100Cr, MIL-101Cr, MIL-100Fe, MIL-177-LT, MIL-177-HT, MIL-45Co, MIL-45Fe, MIL-53Al, MIL-53Sc, MIL-88Sc, MIL-8, MIL-9, MIL-47, MIL-51, MIL-59, MIL-69, MIL-88, MIL-91, MIL-96, MIL-101, MIL-103, MIL-102, MIL-110, and MIL-125.

[0015] In some implementations, the general chemical formula of Mxene is M n+1 X n T m Where M is one or more of the elements such as chromium, molybdenum, manganese, iron, cobalt, copper, aluminum, silver, nickel, palladium, platinum, and ruthenium, and n = 1, 2, or 3; X is carbon or nitrogen; and Tm is one or more of the elements such as hydroxyl, -O-, and halogen groups.

[0016] The second aspect of this application provides a method for preparing the composite lithium supplement agent described in the first aspect above, comprising the following steps:

[0017] S1. Dissolve monolayer Mxene in water and stir at room temperature to obtain a colloidal solution with a mass fraction of 1%~2%;

[0018] S2. Add the organic lithium supplement to the colloidal solution and stir at 15℃~30℃ to obtain the first mixture;

[0019] S3. Add MOF to the first mixture, dilute and ultrasonically stir to obtain the second mixture, and perform vacuum freeze-drying on the second mixture to obtain the organic lithium supplement - Mxene / MOF material, i.e., composite lithium supplement;

[0020] The layer thickness of Mxene is 1nm to 2nm, and the length and width dimensions of Mxene are both 0.5μm to 1.5μm.

[0021] The mass ratio of organic lithium supplement, Mxene, and MOF is 1:(1.5~2):(1.5~2.2).

[0022] In some implementations, the room temperature stirring treatment time in step S1 is 4h to 8h.

[0023] In some embodiments, in step S2, the stirring time is 12h to 24h, and the stirring rate is 500 r / min to 800 r / min.

[0024] In some embodiments, in step S3, the temperature of the ultrasonic stirring treatment is -5℃ to 0℃, the ultrasonic power is 200KW to 300KW, and the time is 10min to 30min.

[0025] In some embodiments, in step S3, the vacuum degree of the vacuum freeze-drying process is 1.3 Pa to 13 Pa, and the temperature is -50°C to -10°C.

[0026] A third aspect of this application provides a battery including a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode and / or the separator includes a composite lithium supplement agent as provided in the first aspect above, or a composite lithium supplement agent prepared according to the preparation method provided in the second aspect above.

[0027] In some embodiments, the positive electrode includes a composite lithium supplement agent, and the composite lithium supplement agent accounts for 2% to 10% of the mass of the positive electrode (100% by mass).

[0028] In this application, MOF and Mxene are added to a composite lithium replenisher. MOF and Mxene can undergo a complexation reaction through their respective surface functional groups to generate a three-dimensional complex, on which the organic lithium replenisher is loaded. Specifically, the metal cations on MOF and the anions on Mxene, such as hydroxyl groups and halide ions, complex. On the one hand, the three-dimensional structure has a larger specific surface area and more conductive sites, allowing the organic lithium replenisher to be uniformly dispersed on the positive electrode and / or separator. Simultaneously, it effectively reduces the impedance of the organic lithium replenisher, increases the delithiation rate of the composite lithium replenisher, and achieves rapid lithium replenishment. On the other hand, it also prevents the aggregation of Mxene or MOF.

[0029] Furthermore, the transition metal elements in MOF can catalyze the decomposition of organic lithium supplements. Simultaneously, MOF can adsorb gases such as CO2 produced during the decomposition of organic lithium supplements, effectively preventing battery performance degradation caused by gas generation from organic lithium supplements and improving battery cycle performance. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of the preparation method of the composite lithium supplement in one embodiment of this application. Detailed Implementation

[0031] A detailed reference is now provided to embodiments of this application, one or more of which are described below. Each embodiment is provided for explanation and not for limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0032] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0033] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0034] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0035] In this article, when referring to units for data ranges, if the unit is only followed by the right endpoint, it means that the units for the left and right endpoints are the same. For example, 100~150 nm means that the units for the left endpoint "100" and the right endpoint "150" are both nm (nanometers).

[0036] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0037] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0038] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates 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.

[0039] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0040] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0041] The first aspect of this application provides a composite lithium supplement agent, comprising an organic lithium supplement agent, a MOF, and Mxene. The organic lithium supplement agent comprises an organic lithium supplement agent with the general formula Li2C. n O n (n≥2) and / or the general formula is Li2C n O n+2 Compounds with n≥2. MOFs are synthesized from different transition metal elements and dicarboxylic acid ligands such as succinic acid and glutaric acid. MOFs and Mxenes can undergo complexation reactions through their respective surface functional groups to form complexes with three-dimensional structures. Organic lithium supplements are loaded onto the complexes.

[0042] In some embodiments, the mass ratio of the organic lithium supplement, Mxene, and MOF is 1:(1.5~2):(1.5~2.2).

[0043] In some implementations, Li2C n O n (n≥2) are cyclic, including at least one of compounds with structures of formulas (I) to (IV).

[0044] , , , .

[0045] In some implementations, Li2C n O n+2 (n≥2) are chain-like, including at least one of compounds with structures of formulas (V) to (VII).

[0046] , , .

[0047] In some embodiments, the MOF includes one or more of MIL-53Cr, MIL-100Cr, MIL-101Cr, MIL-100Fe, MIL-177-LT, MIL-177-HT, MIL-45Co, MIL-45Fe, MIL-53Al, MIL-53Sc, MIL-88Sc, MIL-8, MIL-9, MIL-47, MIL-51, MIL-59, MIL-69, MIL-88, MIL-91, MIL-96, MIL-101, MIL-103, MIL-102, MIL-110, and MIL-125.

[0048] In some implementations, the general chemical formula of Mxene is M n+1 X n T m Where M is one or more of the elements such as chromium, molybdenum, manganese, iron, cobalt, copper, aluminum, silver, nickel, palladium, platinum, and ruthenium, and n = 1, 2, or 3; X is carbon or nitrogen; and Tm is one or more of the elements such as hydroxyl, -O-, and halogen groups.

[0049] In this application, MOF and Mxene are added to a composite lithium replenisher. MOF and Mxene can undergo a complexation reaction through their respective surface functional groups to generate a three-dimensional complex, on which the organic lithium replenisher is loaded. Specifically, the metal cations on MOF and the anions on Mxene, such as hydroxyl groups and halide ions, complex. On the one hand, the three-dimensional structure has a larger specific surface area and more conductive sites, allowing the organic lithium replenisher to be uniformly dispersed on the positive electrode and / or separator. Simultaneously, it effectively reduces the impedance of the organic lithium replenisher, increases the delithiation rate of the composite lithium replenisher, and achieves rapid lithium replenishment. On the other hand, it also prevents the aggregation of Mxene or MOF.

[0050] Furthermore, the transition metal elements in MOF can catalyze the decomposition of organic lithium supplements. Simultaneously, MOF can adsorb gases such as CO2 produced during the decomposition of organic lithium supplements, effectively preventing battery performance degradation caused by gas generation from organic lithium supplements and improving battery cycle performance.

[0051] like Figure 1 As shown, a second aspect of this application provides a method for preparing the composite lithium supplement described in the first aspect, comprising the following steps:

[0052] S1. Dissolve monolayer Mxene in water and stir at room temperature to obtain a colloidal solution with a mass fraction of 1%~2%.

[0053] S2. Add the organic lithium supplement to the colloidal solution and stir at 15℃~30℃ to obtain the first mixture.

[0054] S3. Add MOF to the first mixture, dilute and ultrasonically stir to obtain the second mixture, and perform vacuum freeze-drying on the second mixture to obtain the organic lithium supplement - Mxene / MOF material, i.e., composite lithium supplement.

[0055] In some implementations, the layer thickness of Mxene is 1nm to 2nm, including but not limited to 1nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, and 2nm.

[0056] In some implementations, the length and width dimensions of Mxene are both 0.5μm to 1.5μm, including but not limited to 0.5μm, 0.7μm, 0.9μm, 1.1μm, 1.3μm, and 1.5μm.

[0057] In some embodiments, the mass ratio of the organic lithium supplement, Mxene, and MOF is 1:(1.5~2):(1.5~2.2).

[0058] In some embodiments, the room temperature stirring treatment time in step S1 is 4h to 8h, including but not limited to 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, and 8h.

[0059] In some embodiments, the stirring time in step S2 is 12h to 24h, including but not limited to 12h, 12.5h, 13h, 13.5h, 14h, 14.5h, 15h, 15.5h, 17h, 18h, 19h, 20h, 22h, and 24h.

[0060] In some embodiments, in step S2 above, the stirring rate is 500 r / min to 800 r / min, including but not limited to 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min, and 800 r / min.

[0061] In some embodiments, the temperature of the ultrasonic stirring treatment in step S3 is -5℃ to 0℃, including but not limited to -5℃, -4℃, -3℃, -2℃, -1℃, and 0℃.

[0062] In some embodiments, the ultrasonic power of the ultrasonic stirring process in step S3 is 200KW~300KW, including but not limited to 200KW, 220KW, 240KW, 260KW, 280KW, and 300KW.

[0063] In some embodiments, the ultrasonic stirring time in step S3 is 10 min to 30 min, including but not limited to 10 min, 15 min, 20 min, 25 min, and 30 min.

[0064] In some embodiments, the vacuum degree of the vacuum freeze-drying process in step S3 is 1.3 Pa to 13 Pa, including but not limited to 1.3 Pa, 2 Pa, 3 Pa, 4 Pa, 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa, 10 Pa, 11 Pa, 12 Pa, and 13 Pa.

[0065] In some embodiments, the temperature of the vacuum freeze-drying process in step S3 is -50℃ to -10℃, including but not limited to -50℃, -40℃, -30℃, -20℃, and -10℃.

[0066] It is understood that the solvent used for dilution in step S3 is not particularly limited in this application. Without departing from the inventive concept of this application, any known solvent that can be used for dilution can be applied to this application. The following are merely illustrative examples and not a limitation on the scope of protection. The solvent used for dilution can be distilled water, deionized water, purified water, etc.

[0067] A third aspect of this application provides a battery including a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode and / or the separator includes a composite lithium supplement agent as provided in the first aspect above, or a composite lithium supplement agent prepared according to the preparation method provided in the second aspect above.

[0068] In some embodiments, the positive electrode includes a composite lithium supplement agent, and the mass percentage of the composite lithium supplement agent is 2% to 10% based on 100% of the mass of the positive electrode, including but not limited to 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%.

[0069] In some embodiments, the positive electrode further includes a positive electrode active material, which is a compound capable of reversibly inserting and deintercalating lithium. The continuous oxidative decomposition voltage of the positive electrode active material is ≥4.5V. For example, the positive electrode active material is lithium nickel manganese oxide.

[0070] In some embodiments, the positive electrode also includes a positive electrode binder, a positive electrode conductive agent, and a positive electrode current collector.

[0071] Understandably, this application does not impose any particular restrictions on the positive electrode current collector, as long as it is conductive and does not cause chemical changes in the solid-state battery. Specifically, copper, stainless steel, aluminum, nickel, titanium, or metal current collectors with surfaces treated with carbon or other substances can be used.

[0072] Positive electrode binders are primarily used to bond the positive electrode active material, positive electrode conductive agent, and positive electrode current collector together. Positive electrode binders include, but are not limited to, one or more of the following: polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyoxymethylene (POM), polycarbonate (PC), polyamide (PA), acrylic plastics, other polyolefins and their copolymers, polysulfone, polyphenylene oxide (PPO), and carboxymethyl cellulose (CMC). Further, the binder is either polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF).

[0073] The positive electrode conductive agent is mainly used to assist and improve the conductivity in secondary batteries, and there are no particular limitations on it in this application, as long as it is conductive and does not cause chemical changes. Specifically, the positive electrode conductive agent may contain graphite, such as natural graphite or artificial graphite; carbon materials, such as conductive carbon black (super P), acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal cracking black; conductive fibers, such as carbon fibers and metal fibers; conductive tubes, such as carbon nanotubes; metal powders, such as fluorocarbon powders, aluminum powders, and nickel powders; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxides; and polyphenylene derivatives. From the perspective of improving conductivity, the positive electrode conductive agent is preferably carbon black.

[0074] In some embodiments, the positive electrode can be manufactured by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and rolling, wherein the positive electrode slurry includes a solvent and positive electrode active material and / or positive electrode binder and positive electrode conductive agent dissolved in the solvent.

[0075] The solvent may include an organic solvent, such as N-methyl-2-pyrrolidone (NMP), and the amount used may be such that a preferred viscosity is obtained when the positive electrode active material is included and, selectively, a positive electrode binder, a positive electrode conductive agent, etc. are included. For example, the amount of solvent included in the positive electrode slurry may be such that the concentration of the solids containing the positive electrode active material and, selectively, the positive electrode binder and the positive electrode conductive agent is 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.

[0076] In some embodiments, the positive electrode can be prepared by a dry method, that is, by mixing the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder. Alternatively, the positive electrode active material and the positive electrode conductive agent can be mixed first, and then the positive electrode binder can be added. Under the action of high shear force, the binder changes from a powder state to a fibrous state, which binds the positive electrode active material and the positive electrode conductive agent together. The positive electrode active layer is formed by rolling, and finally the positive electrode active layer and the positive electrode current collector are rolled together to obtain the positive electrode.

[0077] It is understood that the negative electrode is not specifically limited in this application. As long as it can function as the negative electrode of the battery, it is acceptable, provided it conforms to the overall inventive concept of this application. As an example only, the negative electrode includes a negative electrode current collector, a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder.

[0078] In some embodiments, the shape of the negative electrode current collector includes any one of a foil shape, a plate shape, or a grid shape;

[0079] Furthermore, the negative electrode current collector includes, but is not limited to, any one of aluminum, copper, nickel or zinc; optionally, the negative electrode current collector is copper, such as copper foil.

[0080] Furthermore, the negative electrode current collector includes any one of aluminum, copper, nickel, or zinc alloys.

[0081] In some embodiments, the negative electrode active material includes, but is not limited to, one or more of graphite, silicon, silicon oxide, silicon carbon, lithium titanate, hard carbon, soft carbon, tin oxide, and titanium dioxide.

[0082] In some embodiments, the negative electrode conductive agent includes, but is not limited to, carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, super-P, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene)polysulfonated styrene, etc.

[0083] In some embodiments, the negative electrode binder includes, but is not limited to, one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyoxymethylene (POM), polycarbonate (PC), polyamide (PA), acrylic plastics, other polyolefins and their copolymers, polysulfone, polyphenylene ether (PPO), and carboxymethyl cellulose (CMC). Further, the binder is polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF).

[0084] It is understood that no particular limitation is made to the battery preparation method in this application. Any known process method that can be used to prepare batteries can be applied to this application without departing from the inventive concept of this application.

[0085] The present application will be further described below with reference to specific embodiments and comparative examples.

[0086] Example 1

[0087] Preparation of composite lithium supplement

[0088] The organic lithium supplement (Li2C2O4), MOF (MIL-53Cr), and Mxene (Cr3C2OH) were weighed according to a mass ratio of 1:1.8:1.8. The chromium ions on MIL-53Cr and the OH functional groups on Cr3C2OH form a complex, creating a three-dimensional structure.

[0089] S1. Dissolve monolayer Mxene in water and stir at room temperature for 6 hours to obtain a colloidal solution with a mass fraction of 1.5%; wherein the layer thickness of Mxene is 1.5 nm and the length and width dimensions of Mxene are both 1 μm.

[0090] S2. Add the organic lithium supplement to the Mxene solution and stir for 18 hours at a temperature of 20℃ and a rotation speed of 600 r / min to obtain the first mixture.

[0091] S3. Add MOF to the first mixture, dilute with distilled water, and ultrasonically stir for 20 min to obtain the second mixture. Perform vacuum freeze-drying on the second mixture to obtain powdered organic lithium supplement - Mxene / MOF material, i.e., composite lithium supplement.

[0092] The ultrasonic stirring treatment was carried out under ice bath conditions at a temperature of 0℃ and an ultrasonic power of 200KW; the vacuum freeze-drying treatment was carried out at a temperature of -20℃ and a vacuum degree of 5Pa.

[0093] Preparation of positive electrode

[0094] A composite lithium supplement agent is added to the positive electrode slurry to prepare a mixed slurry. The mass ratio of the composite lithium supplement agent to the positive electrode material in the positive electrode slurry is 5:95. The positive electrode material includes lithium nickel manganese oxide (CPMA) as the positive electrode active material, PVDF (PVDF) as the positive electrode binder, and Super P (Super P) as the positive electrode conductive agent (the mass ratio of the positive electrode active material, positive electrode binder, and positive electrode conductive agent is 94:3:3). The mixed slurry is coated onto aluminum foil, dried, and then rolled to obtain the positive electrode.

[0095] The negative electrode is a graphite negative electrode, the separator is a PE membrane (self-made), and the electrolyte is EC:DMC = 1:1 vol.

[0096] Battery manufacturing

[0097] The positive electrode, negative electrode, and separator are wound / stacked to form a cell. Electrolyte is injected into the cell, and the cell is then vacuum-sealed, left to stand, and formed to produce a battery.

[0098] Example 2

[0099] The difference between this embodiment and Example 1 is that the mass ratio of the organic lithium supplement, Mxene, and MOF is different.

[0100] Example 3

[0101] The difference between this embodiment and Example 1 is that the mass ratio of the organic lithium supplement, Mxene, and MOF is different.

[0102] Example 4

[0103] The difference between this embodiment and Example 1 is that the mass ratio of the organic lithium supplement, Mxene, and MOF is different.

[0104] Example 5

[0105] The difference between this embodiment and Embodiment 1 is that the types of organic lithium supplement, Mxene, and MOF selected are different.

[0106] Example 6

[0107] The difference between this embodiment and Example 1 is that the mass ratio of the organic lithium supplement, Mxene, and MOF is different.

[0108] Comparative Example 1

[0109] The difference between Comparative Example 1 and Example 1 is that Mxene and MOF were not added to the positive electrode.

[0110] Comparative Example 2

[0111] The difference between Comparative Example 1 and Example 1 is that Mxene was not added to the positive electrode.

[0112] Comparative Example 3

[0113] The difference between Comparative Example 1 and Example 1 is that MOF was not added to the positive electrode.

[0114] Comparative Example 4

[0115] The difference between Comparative Example 1 and Example 1 is that no organic lithium supplement, Mxene, and MOF were added to the positive electrode.

[0116] The experimental parameters of the examples and comparative examples are summarized in Table 1 below:

[0117]

[0118] Test case

[0119] (1) Determination of cycle performance

[0120] The prepared battery was subjected to cycle testing. At a temperature of 45℃±2℃, the first step involved charging at 0.1C to a termination voltage of 4.95V and a cutoff current of 0.05C, followed by a resting period of 30 minutes. The second step involved discharging at 0.1C to a final discharge voltage (3.5V), recording the discharge capacity, and then resting for 30 minutes. This process of first and second steps was repeated for 100 cycles to test the battery's cycle performance. The test results are shown in Table 2.

[0121] (2) Battery thickness change test

[0122] After 100 battery cycles, the battery thickness change rate was tested. The test results are shown in Table 2.

[0123] (3) Testing of battery internal resistance

[0124] After the battery was prepared using the above method, its internal resistance was measured using a voltage internal resistance meter. The test results are shown in Table 2.

[0125]

[0126] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A composite lithium supplement, characterized in that, This includes organic lithium supplements, MOFs, and Mxene, wherein the organic lithium supplements include those with the general formula Li2C. n O n and / or with the general formula Li2C n O n+2 The compound, the Li2C n O n The Li2C satisfies n≥3 n O n+2 Satisfying n≥2; The MOF is synthesized from transition metal elements and dicarboxylic acid ligands; The MOF and the Mxene undergo a complexation reaction to generate a complex with a three-dimensional structure. The organic lithium supplement is loaded onto the complex; The mass ratio of the organic lithium supplement, the Mxene, and the MOF is 1:(1.5~2):(1.5~2.2).

2. The composite lithium supplement agent according to claim 1, characterized in that, The Li2C n O n n≥3 are cyclic, including at least one of compounds with structures of formulas (I) to (IV). 、 、 、 。 3. The composite lithium supplement agent according to claim 1, characterized in that, The Li2C n O n+2 n≥2 are chain-like, including at least one of compounds with structures of formulas (V) to (VII). 、 、 。 4. The composite lithium supplement agent according to claim 1, characterized in that, The MOF includes one or more of MIL-53Cr, MIL-100Cr, MIL-101Cr, MIL-100Fe, MIL-177-LT, MIL-177-HT, MIL-45Co, MIL-45Fe, MIL-53Al, MIL-53Sc, MIL-88Sc, MIL-8, MIL-9, MIL-47, MIL-51, MIL-59, MIL-69, MIL-88, MIL-91, MIL-96, MIL-101, MIL-103, MIL-102, MIL-110, and MIL-125.

5. The composite lithium supplement agent according to claim 1, characterized in that, The general chemical formula of the Mxene is M n+1 X n T m Where M is one or more of the elements chromium, molybdenum, manganese, iron, cobalt, copper, silver, nickel, palladium, platinum, and ruthenium, and n = 1, 2, or 3; X is carbon or nitrogen; and Tm is one or more of the elements hydroxyl, -O-, and halogen groups.

6. A method for preparing a composite lithium supplement as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Dissolve monolayer Mxene in water and stir at room temperature to obtain a colloidal solution with a mass fraction of 1%~2%; S2. Add the organic lithium supplement to the colloidal solution and stir at 15℃~30℃ to obtain the first mixture; S3. Add MOF to the first mixture, dilute and ultrasonically stir to obtain a second mixture, and perform vacuum freeze-drying on the second mixture to obtain organic lithium supplement - Mxene / MOF material, i.e., composite lithium supplement; The layer thickness of the Mxene is 1nm to 2nm, and the length and width dimensions of the Mxene are both 0.5μm to 1.5μm. The mass ratio of the organic lithium supplement, the Mxene, and the MOF is 1:(1.5~2):(1.5~2.2).

7. The method for preparing the composite lithium supplement according to claim 6, characterized in that, In step S1, the room temperature stirring treatment time is 4h~8h; And / or in step S2, the stirring treatment time is 12h~24h, and the stirring treatment rate is 500 r / min~800 r / min; And / or in step S3, the temperature of the ultrasonic stirring treatment is -5℃ to 0℃, the ultrasonic power is 200KW to 300KW, and the time is 10min to 30min; And / or in step S3, the vacuum degree of the vacuum freeze-drying process is 1.3 Pa to 13 Pa, and the temperature is -50 °C to -10 °C.

8. A battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode and / or the separator comprises a composite lithium supplement as described in any one of claims 1-5, or a composite lithium supplement prepared by the preparation method according to claim 6 or 7.

9. The battery according to claim 8, characterized in that, The positive electrode includes the composite lithium supplement agent, and the mass percentage of the composite lithium supplement agent is 2% to 10% based on the mass of the positive electrode being 100%.

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