Organic lithium supplement agent and preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to an organic lithium supplement agent and a preparation method and application thereof. Provided is an organic lithium supplement comprising: a lithium source three-dimensional skeleton; the lithium source core is connected to the lithium source three-dimensional framework through a chemical bond; the voltage sensitive molecules are grafted to the lithium source three-dimensional framework through chemical bonds; and the lithium source core is stacked and surrounded. According to the organic lithium supplement agent, a lithium source core is stably connected to a lithium source three-dimensional framework through chemical bonds, and meanwhile voltage-sensitive molecules are introduced to be grafted to the framework and surround the lithium source core. According to the structural design, the core of the lithium source is stably fixed, the loss of the lithium source in the charging and discharging process of the battery is avoided, and the continuity of lithium supplement is guaranteed; the voltage-sensitive molecules are stacked around the lithium source core, the release process of the lithium source can be regulated and controlled according to the voltage change of the battery, on-demand lithium supplementation is realized, and the charge-discharge efficiency and the cycle stability of the battery are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to an organic lithium supplementing agent and a preparation method and application thereof. BACKGROUND

[0002] During the first charge-discharge process of a lithium ion battery, a solid electrolyte interface film (SEI film) is generated by the reaction between the surface of a negative electrode material and an electrolyte, which irreversibly consumes 5%-20% of lithium ions deintercalated from a positive electrode, resulting in a significant decrease in the first coulombic efficiency of the battery (usually < 90%). In addition, the continuous rupture and regeneration of the SEI film during cycling will exacerbate the dissolution of transition metal elements in the positive electrode material, causing the oxidative decomposition of the electrolyte and uneven lithium deposition, and ultimately leading to accelerated capacity decay of the battery (capacity retention rate < 80% after 500 cycles).

[0003] The currently used lithium supplementing agents include inorganic lithium supplementing agents or organic lithium supplementing agents. The inorganic lithium supplementing agents (such as Li5FeO4, Li2O) have a too high decomposition voltage to match the deintercalation potential of a high-nickel positive electrode, and the dissolution of transition metals will catalyze the decomposition of the electrolyte, generating > 10 mL / Ah of gas and posing a safety hazard. The organic lithium supplementing agents (such as polyether amine-based materials) include carboxylate groups (-COOLi), which are prone to decarboxylation under high pressure, releasing CO2 and generating electrochemically inert residues, resulting in a sharp decrease in the lithium supplementing efficiency with cycling. At the same time, the lithium transport of the organic lithium supplementing agents depends on a single ion hopping path, and the capacity loss rate is high at high rates. Moreover, the structural degradation leads to the disordered release of active lithium and the occurrence of side reactions.

[0004] Therefore, the above problems will limit the application of lithium supplementing agents in high-voltage and high-energy-density battery systems. There is an urgent need to develop a new type of organic lithium supplementing agent with high lithium content, controllable decomposition voltage, zero metal dissolution, and long-term structural stability, to directly compensate for the loss of active lithium, improve the energy density and cycle life, and avoid the safety hazards and performance degradation problems of existing technologies. SUMMARY

[0005] The application aims to provide an organic lithium supplementing agent and a preparation method and application thereof, and aims to solve the problem that the lithium supplementing agents in the prior art cannot achieve full-cycle lithium supplementing.

[0006] To achieve the above application purposes, the technical solutions adopted by the application are as follows: In a first aspect, the application provides an organic lithium supplementing agent, which comprises: a lithium source three-dimensional framework; a lithium source core connected to the lithium source three-dimensional framework by a chemical bond; a voltage-sensitive molecule grafted to the lithium source three-dimensional framework by a chemical bond, and accumulated around the lithium source core.

[0007] In some embodiments, the organic lithiation supplement includes a decomposition voltage as follows: The decomposition voltage of the first stage ranges from 2.5 to 3.5 V; The decomposition voltage of the second stage ranges from 3.5 to 4.2 V; The decomposition voltage of the third stage is greater than 4.2 V.

[0008] In some embodiments, the lithium source core includes a phosphonate lithium compound containing a six-membered ring, and the six-membered ring is composed of carbon, hydrogen, oxygen, or nitrogen elements.

[0009] In some embodiments, the molar ratio of the lithium source core and the lithium source three-dimensional framework is 1:(0.5-2).

[0010] In some embodiments, the voltage-sensitive molecule includes a fused ring imide compound.

[0011] In some embodiments, the lithium source three-dimensional framework includes one or both of a lithium heterocycle containing oxygen or nitrogen and a lithium complex.

[0012] In some embodiments, the lithium source three-dimensional framework includes a lithium heterocycle containing oxygen or nitrogen and a lithium complex, and the molar ratio of the lithium heterocycle containing oxygen or nitrogen and the lithium complex is 1:(0.3-3).

[0013] In some embodiments, the lithium heterocycle containing oxygen or nitrogen and the lithium complex are connected to each other by hydrogen bonds.

[0014] In some embodiments, the lithium source core is connected to the lithium heterocycle containing oxygen or nitrogen by a covalent bond, and the binding energy is 3.5-4.9 eV.

[0015] In some embodiments, the lithium source core is connected to the lithium complex by a non-covalent bond, and the binding energy is 1.2-2.3 eV.

[0016] In some embodiments, the organic lithiation supplement further includes a free radical trapping molecule, and the free radical trapping molecule is connected to the voltage-sensitive molecule by a covalent bond.

[0017] In some embodiments, the phospholipid group on the surface of the lithium source core is combined with the phosphorus-containing molecule through a phosphorus-oxygen bond between the phosphonic groups to form a phospholipid bilayer coating arranged in a direction, and the phospholipid bilayer coating is connected to the lithium source core by hydrogen bonds.

[0018] In some embodiments, the thickness of the phospholipid bilayer coating is 5-8 nm.

[0019] In a second aspect, the embodiments of the present application provide a preparation method of the organic lithiation supplement described above, including the following steps: Mixing and reacting the lithium source core and the lithium source three-dimensional framework in a solvent to form a "lithium source-framework" complex; The organic lithium supplementing agent is prepared by mixing a lithium source-core and a lithium source three-dimensional framework to form a lithium source-framework complex, and then mixing the complex with a voltage-sensitive molecule precursor and performing a grafting reaction to connect the voltage-sensitive molecule to the lithium source three-dimensional framework.

[0020] In a third aspect, the embodiments of the present application provide a positive electrode comprising the organic lithium supplementing agent or the organic lithium supplementing agent prepared by the preparation method of the organic lithium supplementing agent.

[0021] In a fourth aspect, the embodiments of the present application provide an electrolyte comprising the organic lithium supplementing agent or the organic lithium supplementing agent prepared by the preparation method of the organic lithium supplementing agent.

[0022] In a fifth aspect, the embodiments of the present application provide a secondary battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises the positive electrode, or the electrolyte comprises the electrolyte.

[0023] The organic lithium supplementing agent provided in the first aspect of the present application has a lithium source core stably connected to a lithium source three-dimensional framework through a chemical bond, and a voltage-sensitive molecule grafted to the framework and surrounding the lithium source core. This structural design stabilizes the lithium source core and avoids loss of the lithium source during charging and discharging of the battery, ensuring the sustainability of lithium supplementing. The voltage-sensitive molecule surrounds the lithium source core and can regulate the lithium source release process according to the change in the battery voltage, achieving on-demand lithium supplementing and significantly improving the charging and discharging efficiency and cycle stability of the battery. Moreover, there is no transition metal elution in the whole system, avoiding oxidation and decomposition of the electrolyte, and the organic lithium supplementing agent has high lithium content, controllable decomposition voltage, zero metal elution and long-term structural stability, which is conducive to wide application.

[0024] The preparation method of the organic lithium supplementing agent provided in the second aspect of the present application uses a step-by-step reaction method, in which a lithium source core and a lithium source three-dimensional framework are first mixed to form a lithium source-framework complex, and then a grafting reaction is performed on the complex with a voltage-sensitive molecule precursor. This method is simple to operate and has mild reaction conditions, and can precisely control the combination mode and proportion of each component to ensure that the prepared organic lithium supplementing agent has a stable and uniform structure, which is conducive to realizing large-scale industrial production, reducing production costs, and ensuring the consistency and stability of product quality.

[0025] The positive electrode provided in the third aspect of the present application introduces the organic lithium supplementing agent provided in the present application, which can effectively compensate for the loss of lithium during charging and discharging of the positive electrode material, and improve the specific capacity and cycle stability of the positive electrode material. The stage-by-stage decomposition characteristics and voltage-sensitive characteristics of the organic lithium supplementing agent enable the positive electrode to maintain good electrochemical performance in different voltage intervals, improve the overall energy density and charging and discharging efficiency of the battery, and prolong the service life of the battery.

[0026] The electrolyte provided in the fourth aspect of the present application has the advantages of the organic lithium supplementing agent. The lithium source structure can efficiently supplement lithium, improve the capacity and service life of the battery; the voltage-sensitive molecules can sensitively respond to voltage changes, optimize the charge and discharge performance, and enhance the safety; at the same time, the three-dimensional structure of the organic lithium supplementing agent can improve the compatibility of the electrolyte with the electrode material and reduce the interface impedance; the stable molecular structure also ensures the consistency and stability of the performance of the electrolyte under different conditions, and comprehensively improves the reliability and environmental adaptability of the battery.

[0027] The secondary battery provided in the fifth aspect of the present application has the advantages of the organic lithium supplementing agent. The secondary battery can effectively improve the capacity decay problem caused by lithium loss, improve the cycle performance of the battery; the regulation effect of the organic lithium supplementing agent on the battery voltage and the free radical capture ability enhance the safety of the battery and reduce the risk of thermal runaway of the battery; at the same time, the optimization of the lithium ion transmission and the charge and discharge process improves the energy density and the charge and discharge efficiency of the battery, so that the secondary battery has better comprehensive performance and market competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 is a structural schematic diagram of the organic lithium supplementing agent provided in the embodiments of the present application.

[0030] In the drawings, various reference signs represent: 1—lithium source three-dimensional skeleton; 2—lithium source core; 3—voltage-sensitive molecule; 4—free radical capture molecule; 5—phospholipid bilayer coating. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0032] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which means that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0033] In this application, "at least one" means one or more, "multiple" means two or more. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0034] It should be understood that the size of the sequence number of the above-mentioned processes in various embodiments of the present application does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0035] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0036] The weight of the related components mentioned in the embodiments of the present application can not only refer to the specific content of each component, but also represent the weight ratio relationship between each component, therefore, as long as the content of the related components in the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiments of the present application. Specifically, the mass in the embodiments of the present application can be µg, mg, g, kg, and other mass units commonly known in the chemical field.

[0037] The terms "first", "second" are only for the purpose of description, used to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. For example, without departing from the scope of the embodiments of the present application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features.

[0038] The first aspect of the embodiments of the present application provides an organic lithium supplementing agent, such as Figure 1 As shown in the formula, the organic lithium supplementing agent comprises: A lithium source three-dimensional skeleton 1; A lithium source core 2 connected to the lithium source three-dimensional skeleton 1 by a chemical bond; A voltage-sensitive molecule 3 grafted to the lithium source three-dimensional skeleton 1 by a chemical bond, and accumulated around the lithium source core 2.

[0039] The organic lithium replenisher provided in the first aspect of this application has a lithium source core 2 firmly connected to the three-dimensional lithium source framework 1 by chemical bonds, and a voltage-sensitive molecule 3 grafted onto the framework and surrounding the lithium source core 2. This structural design ensures that the lithium source core 2 is stably fixed, preventing lithium loss during battery charging and discharging and ensuring continuous lithium replenishment. The voltage-sensitive molecule 3, stacked around the lithium source core 2, can regulate the lithium release process according to changes in battery voltage, achieving on-demand lithium replenishment and significantly improving the battery's charging and discharging efficiency and cycle stability. Furthermore, the entire system has no transition metal dissolution, avoiding electrolyte oxidation and decomposition, resulting in an organic lithium replenisher with high lithium content, controllable decomposition voltage, zero metal dissolution, and long-term structural stability, which is beneficial for wide application.

[0040] In some embodiments, the organic lithium supplement includes the following decomposition voltage: The decomposition voltage range for the first stage is 2.5-3.5V. Under the action of the decomposition voltage in the first stage, the electron cloud of the voltage-sensitive molecule 3 unit will rearrange, which can activate the lithium source three-dimensional framework 1 to release lithium ions.

[0041] The decomposition voltage range for the second stage is 3.5-4.2V. Under the action of the decomposition voltage in the second stage, the voltage-sensitive molecule 3 unit will be oxidized and open the ring, triggering the decomposition of the lithium source core 2 and releasing lithium ions.

[0042] The decomposition voltage in the third stage is greater than 4.2V. Under the action of the decomposition voltage in the third stage, the phospholipid bilayer will disintegrate, and the remaining lithium ions will be completely released.

[0043] Therefore, the organic lithium replenisher provided in this application, by combining its components, can achieve phased lithium ion release under the action of decomposition voltages at three different stages, thus realizing a full-cycle lithium replenishment effect.

[0044] The organic lithium supplement includes a three-dimensional lithium source framework 1; in some embodiments, the three-dimensional lithium source framework 1 includes one or two of oxygen- or nitrogen-containing lithium heterocycles and lithium complexes.

[0045] In some embodiments, the three-dimensional framework 1 of the lithium source is composed of lithium heterocycles containing oxygen or nitrogen and lithium complexes interconnected by coordination bonds and hydrogen bonds. This composite structure endows the framework with good flexibility and stability, enabling it to adapt to the complex electrochemical environment inside the battery.

[0046] In some embodiments, the three-dimensional framework of the lithium source comprises an oxygen- or nitrogen-containing lithium heterocycle and a lithium complex, and the molar ratio of the oxygen- or nitrogen-containing lithium heterocycle to the lithium complex is 1:0.3 to 3. In some specific embodiments, the molar ratio of the oxygen- or nitrogen-containing lithium heterocycle to the lithium complex includes, but is not limited to, typical but non-limiting values ​​such as 1:0.3, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, and 1:3.

[0047] In some embodiments, the oxygen- or nitrogen-containing lithium heterocycle and the lithium complex are interconnected by hydrogen bonds. In some embodiments, the oxygen- or nitrogen-containing lithium heterocycle serves as a rigid framework, providing lithium-ion storage sites through dynamic recombination of oxygen- or nitrogen-containing bond energies; the lithium complex serves as a flexible ligand, and the two are connected through synergistic hydrogen bonding to jointly form a dynamic lithium transport network.

[0048] In some implementations, the oxygen- or nitrogen-containing lithium heterocycles include, but are not limited to, lithium-boron-oxygen six-membered rings or lithium-boron-nitrogen six-membered rings; the lithium complexes include, but are not limited to, any one of crown ethers, thiocrown ethers, and azacrown ethers.

[0049] In some specific implementations, when the oxygen- or nitrogen-containing lithium heterocycle is selected from a lithium boron-oxygen six-membered ring, and the lithium complex is selected from a crown ether, the oxygen atom of the lithium boron-oxygen six-membered ring forms a hydrogen bond (bond length approximately 0.2-0.3 nm) with the ether oxygen atom of the crown ether, while the Li in the crown ether... + Coordination sites and Li of the boron-oxygen ring + Storage sites share electron density, where the oxygen atom in the lithium boron oxygen six-membered ring interacts with Li. + The binding energy of the oxygen atom in the crown ether binds with the Li through lone pair electrons. + Different binding energies create a coordination intensity gradient from weak to strong, enabling the preparation of multi-level coordination channels.

[0050] Furthermore, the lithium source core 2 is connected to the lithium source three-dimensional framework 1 by chemical bonds.

[0051] In some embodiments, the lithium source core 2 includes a lithium phosphate compound containing a six-membered ring, wherein the six-membered ring is composed of carbon, hydrogen, oxygen or nitrogen.

[0052] In some embodiments, the lithium source core 2 includes, but is not limited to, compounds such as lithium 1,3,5-triazine phosphate, lithium phenoxy phosphate (C6H5-O-PO3Li2), and lithium tricyanate phosphate.

[0053] In some embodiments, the lithium source core 2 comprises lithium 1,3,5-triazine phosphate, with each molecule carrying two releasable lithium ions.

[0054] The structural formula of lithium 1,3,5-triazine phosphate is as follows: The provided lithium 1,3,5-triazine phosphate can release 2 Li₂ molecules per molecule. + Therefore, it is beneficial to provide lithium replenishment capacity.

[0055] In some embodiments, the molar ratio of the lithium source core 2 to the lithium source three-dimensional framework 1 is 1:(0.5-2). Specifying a molar ratio of 1:(0.5-2) for the lithium source core 2 and the lithium source three-dimensional framework 1 ensures an optimal composite structure, guaranteeing that the lithium source core 2 is firmly bonded to the framework while maximizing the release efficiency of the lithium source. In some specific implementations, the molar ratio of the lithium source core 2 to the lithium source three-dimensional framework 1 includes, but is not limited to, typical but non-limiting values ​​such as 1:0.5, 1:1, 1:1.5, and 1:2.

[0056] In some embodiments, the lithium source core 2 is covalently bonded to an oxygen- or nitrogen-containing lithium heterocycle with a binding energy of 3.5–4.9 eV; the lithium source core 2 is also non-covalently bonded to a lithium complex with a binding energy of 1.2–2.3 eV. The covalent bonding between the lithium source core 2 and the oxygen- or nitrogen-containing lithium heterocycle, and the non-covalent bonding with the lithium complex, allows the lithium source core 2 to exist stably within the framework while also enabling controllable release of lithium under appropriate conditions. Furthermore, the range of covalent and non-covalent bond binding energies ensures controllable migration of lithium ions during charging and discharging, achieving precise control of the battery's lithium balance and improving the battery's cycle life and safety.

[0057] Furthermore, the organic lithium supplement also includes: voltage-sensitive molecule 3, which is chemically grafted onto the three-dimensional framework 1 of the lithium source and stacked around the core 2 of the lithium source.

[0058] In some embodiments, the voltage-sensitive molecule 3 comprises a fused-ring imide compound. In some embodiments, the fused-ring imide compound includes naphthiimide (NDI), perylene diimide, or derivatives thereof. Choosing a fused-ring imide compound (such as naphthiimide, perylene diimide, or derivatives thereof) as the voltage-sensitive molecule 3 provides a rigid framework for electron transport and delocalization, exhibiting excellent π-π stacking ability and voltage response characteristics. This allows for precise sensing of voltage changes, effective regulation of lithium source release, and further improvement of the battery's voltage adaptability and charge / discharge performance. In specific embodiments, the voltage-sensitive molecule can be intermittently stacked around the lithium source core or continuously and densely stacked.

[0059] In some specific embodiments, naphthaleneimide (NDI) is generated by the condensation reaction of naphthalenetetracarboxylic acid dianhydride and cyclohexanediamine, and its chemical formula is as follows: .

[0060] In some specific embodiments, when a crown ether is selected, the molar ratio of naphthalimide to crown ether is 1:(0.5-4). By limiting the molar ratio of naphthalimide to crown ether, it is beneficial to control the overall content and effect of voltage-sensitive molecule 3 in the organic lithium supplement.

[0061] In some embodiments, such as Figure 1 As shown, the organic lithium supplement also includes a free radical scavenging molecule 4, which is covalently linked to the voltage-sensitive molecule 3. The free radical scavenging molecule 4 includes phosphorus atoms, which capture electrolyte free radicals via lone pair electrons. The phosphorus atoms in the free radical scavenging molecule 4 utilize lone pair electrons to capture electrolyte free radicals, effectively suppressing side reactions caused by free radicals within the battery, reducing active material loss, and lowering the rate of increase in battery internal resistance. This improves the battery's cycle stability and lifespan, while also reducing safety risks such as thermal runaway caused by side reactions.

[0062] In some embodiments, the free radical scavenging molecule 4 includes any one of diphenylphosphonate (DPPA), distearate, and myristoyl phosphatidyl, whose phosphate groups can provide similar free radical scavenging capabilities.

[0063] In some specific implementations, when a lithium-boron-oxygen six-membered ring is selected, the molar ratio of diphenylphosphonate to lithium-boron-oxygen six-membered ring is 1:5 to 1:10. Controlling the amount of free radical scavenging molecule 4 added can both capture electrolyte free radicals and ensure that the overall structure of the organic lithium supplement is not affected.

[0064] In some embodiments, such as Figure 1 As shown, the phospholipid groups on the surface of the lithium source core 2 are bonded to phosphorus-containing molecules through phosphorus-oxygen bonds between phosphate groups, forming a directionally aligned phospholipid bilayer coating 5. This phospholipid bilayer coating 5 is connected to the lithium source core 2 via hydrogen bonds. This coating effectively isolates the lithium source core 2 from the electrolyte, preventing unnecessary side reactions and protecting the stability of the lithium source. Simultaneously, the directional alignment of the phospholipid bilayer facilitates the directional transport of lithium ions, improving the migration efficiency of lithium ions within the battery and thus enhancing the battery's charge and discharge performance.

[0065] In some embodiments, the thickness of the phospholipid bilayer coating 5 is 5-8 nm. Limiting the thickness of the phospholipid bilayer coating 5 to 5-8 nm ensures effective protection of the lithium source core 2 by the coating layer, preventing electrolyte erosion, while avoiding excessive thickness that could affect the lithium-ion transport rate. This suitable thickness ensures that lithium ions can smoothly pass through the coating layer and react with the lithium source core 2, maintaining good charge-discharge performance and cycle life of the battery while ensuring lithium source stability.

[0066] In some embodiments, the hydrophilic head of the phospholipid bilayer 5 forms a Li group with a diameter of 0.4-0.6 nm. + The lithium transport channel contains oxygen atoms in its phosphate groups. These oxygen atoms can form hydrogen bonds with the amino and hydroxyl groups in the lithium source core 2, thereby self-assembling into a cell membrane-like structure. The formed phospholipid bilayer 5 has a certain membrane fluidity, which determines the lithium-ion diffusion rate. Increased membrane fluidity improves lithium-ion transport efficiency. Unsaturated fatty acids further increase membrane fluidity and promote lithium transport. + Lateral diffusion; saturated fatty acids enhance membrane rigidity and suppress ion transport efficiency; charge distribution: negatively charged surfaces preferentially adsorb Li + This reduces the transmembrane energy barrier and promotes lithium-ion transport.

[0067] A second aspect of this application provides a method for preparing the above-mentioned organic lithium supplement, comprising the following steps: S01. The lithium source core 2 and the lithium source three-dimensional framework 1 are mixed and reacted in a solvent to form a "lithium source-framework" composite. S02. Provide a voltage-sensitive molecule 3 precursor, mix the "lithium source-backbone" complex and the voltage-sensitive molecule 3 precursor in a solvent, and carry out a grafting reaction to attach the voltage-sensitive molecule 3 to the lithium source three-dimensional framework 1 to obtain an organic lithium supplement.

[0068] The method for preparing the organic lithium supplement provided in the second aspect of this application employs a stepwise reaction method. First, a lithium source core 2 and a lithium source three-dimensional framework 1 are mixed and reacted to form a "lithium source-framework" complex. Then, the complex is grafted with a voltage-sensitive molecule 3 precursor. This method is simple to operate, has mild reaction conditions, and can precisely control the binding mode and ratio of each component, ensuring that the prepared organic lithium supplement has a stable and uniform structure. This facilitates large-scale industrial production, reduces production costs, and ensures the consistency and stability of product quality.

[0069] In step S01, the lithium source core 2 and the lithium source three-dimensional framework 1 are mixed and reacted in a solvent to form a "lithium source-framework" composite.

[0070] In some embodiments, the lithium source core 2 comprises lithium 1,3,5-triazine phosphate, and the specific preparation method includes the following steps: Provide the following raw materials in the following quantities: cyanuric acid C3H3N3O3 (5.0 g), lithium phosphate (Li3PO4, 3.2 g), ionic liquid: [EMIM]TFSI (10 mL); The raw materials are mixed and then microwaved (220℃, 300 W, 20 minutes) to form a three-dimensional cross-linked network. LiCl (1.0 g) was added and ultrasonically dispersed in NMP to promote Li... + The lithium 1,3,5-triazine phosphate was obtained by coordination with the -NH2 group of cyanuric acid.

[0071] Cyanuric acid and lithium phosphate undergo condensation polymerization under microwave conditions to form a three-dimensional cross-linked network; the specific reaction formula is as follows: 3C3H3N3O3 (cyanuric acid) + Li3PO4 → [C3H2N3Li2PO4]_m (cross-linked polymer) + H2O.

[0072] In some embodiments, the lithium source three-dimensional framework 1 provides a boron-oxygen lithium ring ([B3O3Li3]n) and a crown ether (lithium complex) ([15-C-5-Li]k). The preparation method includes the following steps: synthesis of boron-oxygen six-membered ring: boric acid (H3BO3) and LiOH (molar ratio 1:1) are refluxed in ethanol to generate B3O3Li3 crystals; synthesis of lithium crown ether-lithium coordination complex: 15-crown-5 ether (0.5 g) and LiPF6 (0.3 g) are stirred in THF for 12 hours to form [15-C-5·Li + Complex.

[0073] Furthermore, the lithium source core 2 and the lithium source three-dimensional framework 1 are mixed and reacted in a solvent to form a "lithium source-framework" complex. The specific steps include: 1) Adding 1 mol of lithium source core 2 and 1 mol of lithium source three-dimensional framework to tetrahydrofuran, heating to 40°C and stirring for 8 hours; 2) Pumping the reacted mixture into an organic spray dryer for drying, with a feed rate of 5 mL / min, an inlet air temperature of 100°C, and an inlet air velocity of 1 L / min.

[0074] In step S02, a voltage-sensitive molecule 3 precursor is provided. The "lithium source-backbone" complex and the voltage-sensitive molecule 3 precursor are mixed in a solvent and a grafting reaction is carried out to attach the voltage-sensitive molecule 3 to the lithium source three-dimensional framework 1 to obtain an organic lithium supplement.

[0075] In some embodiments, the voltage-sensitive molecule 3 is selected from NDI, and the NDI precursor is prepared by hydrothermal synthesis, specifically including: Provide the following raw material of the following quality: 1,4,5,8-naphthalenetetracarboxylic anhydride C 14 H6O6 (5.0 g), cyclohexanediamine C6H 14 N2 (3.2g, molar ratio 1:1.5), deionized water (50 mL); The above raw materials were added to a hydrothermal reactor and reacted at 135°C and 3.5 MPa for 4 hours to generate naphthalimide precursor (NDI-N). Add 2.5 mL of 3-aminopropanol and continue the reaction for 1 hour to introduce terminal hydroxyl groups (diol-NDI). The diol-NDI crystals with a purity ≥99% were obtained by recrystallization with a mixed solvent of ethanol / water (7:3) and vacuum drying.

[0076] In this process, naphthalene dicarboxylic anhydride and cyclohexanediamine undergo a condensation reaction to generate a naphthalimide (NDI) precursor. The reaction involves the amidation of the carboxylic anhydride and the amine. The specific chemical reaction formula is as follows: C 14 H6O6 (naphthalenedicarboxylic anhydride) + C6H 14 N2 (cyclohexanediamine) → C 20 H 16 N2O4 (NDI precursor) + H2O.

[0077] In some embodiments, the step of mixing the "lithium source-backbone" complex and the voltage-sensitive molecule 3 precursor in a solvent includes: dispersing the components of the "lithium source-backbone" complex and the voltage-sensitive molecule 3 precursor in NMP, utilizing the π-π stacking of NDI to form a charge gradient network with the electron-deficient region of the boron oxylithium ring and the electron-rich region of the crown ether; coating into a film (thickness 25 μm), using water / ethanol (1:1) as the coagulation bath, and vacuum drying at 60°C.

[0078] In some embodiments, the method further includes providing a radical scavenging molecule 4, wherein the radical scavenging molecule 4 is diphenyl azidophosphate (DPPA), and the method for synthesizing DPPA includes the following steps: The following raw materials are provided in the following quantities: diphenyl chlorophosphate (47.9 g, 0.178 mol), sodium azide (20.7 g, 0.32 mol), and tetrabutylammonium bromide (2.5 g, phase transfer catalyst). The raw materials were added to a three-necked flask and stirred vigorously at room temperature for 10 hours; then filtered to obtain a slightly viscous liquid DPPA.

[0079] Among them, the chlorine atom (Cl) in DPPCl - ) by azide group (N3) -The substitution of ) produces DPPA: The specific chemical reaction formula is as follows: (C6H5O)2P(O)Cl+NaN3→(C6H5O)2P(O)N3+NaCl.

[0080] In some embodiments, the preparation of DPPA-NDI covalent grafts includes the following steps: Raw materials provided: gradient membrane (1.0 g), diol-NDI (0.5 g), DPPA (C 12 H 10 N3O2P 0.3 g), AIBN (0.05 g); UV-initiated grafting: Under nitrogen protection, 365 nm UV light was irradiated for 30 minutes, AIBN initiated a free radical reaction, and the phosphate group of DPPA formed a POC covalent bond with the hydroxyl group of NDI; Purification process: Wash with ethanol to remove unreacted substances, and dry under vacuum at 60°C for 12 hours.

[0081] In this process, the azide group (-N3) of DPPA undergoes nucleophilic substitution with the hydroxyl group (-OH) of diol-NDI under ultraviolet light initiation to generate a POC bond. The specific chemical reaction formula is as follows: diol-NDI-OH + DPPA-N3 → diol-NDI-OP(O)(C6H5)2 + HN3↑.

[0082] Furthermore, it also includes the formation of a phospholipid bilayer 5, specifically including: providing an organic lithium supplement precursor, DOPC (C 44 H 84 NO8P and NMP; both are dispersed in an NMP solution and induced to form a bilayer by constant voltage of 1.5V.

[0083] A third aspect of this application provides a positive electrode comprising the above-described organic lithium supplement or an organic lithium supplement prepared by the above-described method for preparing the organic lithium supplement.

[0084] The positive electrode provided in the third aspect of this application introduces the organic lithium replenishing agent provided in this application into the positive electrode, which can effectively compensate for the lithium loss of the positive electrode material during charging and discharging, and improve the specific capacity and cycle stability of the positive electrode material; the staged decomposition characteristics and voltage-sensitive characteristics of the organic lithium replenishing agent enable the positive electrode to maintain good electrochemical performance in different voltage ranges, improve the overall energy density and charge and discharge efficiency of the battery, and extend the battery life.

[0085] The fourth aspect of this application provides an electrolyte comprising the above-described organic lithium supplement or an organic lithium supplement prepared by the above-described method for preparing the organic lithium supplement.

[0086] The electrolyte provided in the fourth aspect of this application includes the aforementioned organic lithium replenisher, which offers significant advantages due to its unique structural design. Its lithium source structure enables efficient lithium replenishment, improving battery capacity and lifespan; the voltage-sensitive molecule 3 responds sensitively to voltage changes, optimizing charge-discharge performance and enhancing safety; simultaneously, the three-dimensional structure of the organic lithium replenisher improves the compatibility between the electrolyte and electrode materials, reducing interfacial impedance; and the stable molecular structure ensures the consistency and stability of the electrolyte's performance under different conditions, comprehensively improving battery reliability and environmental adaptability.

[0087] The fifth aspect of this application provides a secondary battery, including a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode includes the aforementioned positive electrode sheet.

[0088] The secondary battery provided in the fifth aspect of this application, because the positive electrode uses a positive electrode sheet containing the organic lithium replenishing agent, can effectively improve the capacity decay problem caused by lithium loss and enhance the cycle performance of the battery; the regulating effect of the organic lithium replenishing agent on battery voltage and its free radical capture ability enhance the safety of the battery and reduce the risk of battery thermal runaway; at the same time, its optimization of lithium ion transport and charge / discharge process improves the energy density and charge / discharge efficiency of the battery, giving the secondary battery better overall performance and market competitiveness.

[0089] The following description is based on specific embodiments.

[0090] Example A1 An organic lithium supplement and its preparation method Organic lithium supplements include: Three-dimensional framework of lithium source 1 (composite of boron-oxygen lithium ring ([B3O3Li3]n) and crown ether); The lithium source core 2 (lithium 1,3,5-triazine phosphate) is chemically bonded to the lithium source three-dimensional framework 1; Voltage-sensitive molecule 3 (naphthalimide (NDI)) is chemically grafted onto the three-dimensional framework 1 of the lithium source; and it surrounds the core 2 of the lithium source through π-π stacking.

[0091] The free radical trapping molecule 4 (diphenyl azidophosphate (DPPA)) is covalently linked to the voltage-sensitive molecule 3.

[0092] The phospholipid bilayer 5 is connected to the lithium source core 2 via hydrogen bonds and has a thickness of 5 nm.

[0093] Preparation methods include: In step S01, the lithium source core 2 and the lithium source three-dimensional framework 1 are mixed and reacted in a solvent to form a "lithium source-framework" composite.

[0094] (1) The lithium source core 2 includes lithium 1,3,5-triazine phosphate, and the specific preparation method includes the following steps: Provide the following raw materials in the following quantities: cyanuric acid C3H3N3O3 (5.0 g), lithium phosphate (Li3PO4, 3.2 g), ionic liquid: [EMIM]TFSI (10 mL); The raw materials are mixed and then microwaved (220℃, 300 W, 20 minutes) to form a three-dimensional cross-linked network. LiCl (1.0 g) was added and ultrasonically dispersed in NMP to promote Li... + The lithium 1,3,5-triazine phosphate was obtained by coordination with the -NH2 group of cyanuric acid.

[0095] Cyanuric acid and lithium phosphate undergo condensation polymerization under microwave conditions to form a three-dimensional cross-linked network; the specific reaction formula is as follows: 3C3H3N3O3 (cyanuric acid) + Li3PO4 → [C3H2N3Li2PO4]_m (cross-linked polymer) + H2O.

[0096] (2) In the three-dimensional framework 1 of the lithium source, a boron-oxygen lithium ring ([B3O3Li3]n) and a crown ether (lithium complex) ([15-C-5-Li]k) are provided. The preparation method includes the following steps: synthesis of boron-oxygen lithium six-membered ring: boric acid (H3BO3) and LiOH (molar ratio 1:1) are refluxed in ethanol to generate B3O3Li3 crystals; synthesis of lithium crown ether-lithium coordination complex: 15-crown-5 ether (0.5 g) and LiPF6 (0.3 g) are stirred in THF for 12 hours to form [15-C-5·Li + Complex.

[0097] (3) The lithium source core 2 and the lithium source three-dimensional framework 1 are mixed and reacted in a solvent to form a "lithium source-framework" complex. The specific steps include: 1) Adding 1 mol of lithium source core 2 and 1 mol of lithium source three-dimensional framework to tetrahydrofuran and heating to 40°C and stirring for 8 hours. 2) Pumping the reaction mixture into an organic spray drying device for drying, with a feed rate of 5 mL / min, an air inlet temperature of 100°C, and an air inlet speed of 1 L / min.

[0098] In step S02, a voltage-sensitive molecule 3 precursor is provided. The "lithium source-backbone" complex and the voltage-sensitive molecule 3 precursor are mixed in a solvent and a grafting reaction is carried out to attach the voltage-sensitive molecule 3 to the lithium source three-dimensional framework 1 to obtain an organic lithium supplement.

[0099] (1) Voltage-sensitive molecule 3 is selected from NDI. The NDI precursor is prepared by hydrothermal synthesis, specifically including: providing the following raw materials by mass: 1,4,5,8-naphthalenetetracarboxylic anhydride C 14H6O6 (5.0 g), cyclohexanediamine C6H 14 N2 (3.2 g, molar ratio 1:1.5), deionized water (50 mL); the above raw materials were added to a hydrothermal reactor and reacted at 135 °C and 3.5 MPa for 4 hours to generate naphthalene diimide precursor (NDI-N); 3-aminopropanol (2.5 mL) was added and the reaction continued for 1 hour to introduce terminal hydroxyl groups (diol-NDI); then recrystallized in a mixed solvent of ethanol / water (7:3), and vacuum dried to obtain diol-NDI crystals with a purity ≥99%.

[0100] In this process, naphthalene dicarboxylic anhydride and cyclohexanediamine undergo a condensation reaction to generate a naphthalimide (NDI) precursor. The reaction involves the amidation of the carboxylic anhydride and the amine. The specific chemical reaction formula is as follows: C 14 H6O6 (naphthalenedicarboxylic anhydride) + C6H 14 N2 (cyclohexanediamine) → C 20 H 16 N2O4 (NDI precursor) + H2O.

[0101] (2) Mix the “lithium source-backbone” complex and voltage-sensitive molecule 3 precursor in a solvent. The steps include: dispersing the components of the “lithium source-backbone” complex and voltage-sensitive molecule 3 precursor in NMP, and using the π-π stacking of NDI to form a charge gradient network with the electron-deficient region of the boron-oxygen lithium ring and the electron-rich region of the crown ether; coating into a film (thickness 25 μm), using water / ethanol (1:1) as the coagulation bath, and vacuum drying at 60℃.

[0102] In step S03, a radical scavenging molecule is provided. First, a radical scavenging molecule (DPPA) is synthesized, and then it is grafted onto a voltage-sensitive molecule.

[0103] (1) Provide radical scavenging molecule 4, wherein radical scavenging molecule 4 is diphenyl azidophosphate (DPPA). The synthesis method of DPPA includes the following steps: providing the following raw materials by mass: diphenyl chlorophosphate (47.9 g, 0.178 mol), sodium azide (20.7 g, 0.32 mol), tetrabutylammonium bromide (2.5 g, phase transfer catalyst); adding the raw materials to a three-necked flask and stirring vigorously at room temperature for 10 hours; then filtering to obtain a slightly viscous liquid DPPA. Wherein, the chlorine atom (Cl) in DPPCl... - ) by azide group (N3) - The substitution of ) produces DPPA: The specific chemical reaction formula is as follows: (C6H5O)2P(O)Cl+NaN3→(C6H5O)2P(O)N3+NaCl.

[0104] (2) Preparation of DPPA-NDI covalent grafting, the specific steps include: providing raw materials: gradient membrane (1.0 g), diol-NDI (0.5 g), DPPA (C 12 H 10 0.3 g of N3O2P and 0.05 g of AIBN were used for UV-initiated grafting: under nitrogen protection, the mixture was irradiated with 365 nm UV light for 30 minutes. AIBN initiated a free radical reaction, and the phosphate group of DPPA formed a POC covalent bond with the hydroxyl group of NDI. Purification was then performed: unreacted substances were removed by washing with ethanol, and the mixture was vacuum dried at 60 °C for 12 hours. Specifically, the azide group (-N3) of DPPA and the hydroxyl group (-OH) of diol-NDI under UV initiation underwent nucleophilic substitution to generate a POC bond. The specific chemical reaction is as follows: diol-NDI-OH + DPPA-N3 → diol-NDI-OP(O)(C6H5)2 + HN3↑.

[0105] In step S04, a phospholipid bilayer is formed with a thickness of 5 nm.

[0106] (1) Specific steps include: providing 5g of organic lithium supplement precursor, 0.1g of DOPC (C 44 H 84 NO8P and 10 mL of NMP were dispersed in the NMP solution, and a bilayer was induced by constant voltage at 1.5V.

[0107] Example A2 An organic lithium supplement and its preparation method Organic lithium supplements include: Three-dimensional framework of lithium source 1 (composite of boron nitrogen lithium ring ([B3N3Li3]n) and crown ether); The lithium source core 2, voltage-sensitive molecule 3, free radical capturing molecule 4, and phospholipid bilayer 5 are all the same as in Example A1.

[0108] Preparation methods include: In step S01, the lithium source core 2 and the lithium source three-dimensional framework 1 are mixed and reacted in a solvent to form a "lithium source-framework" composite.

[0109] (1) The lithium source core 2 is the same as in Example A1.

[0110] (2) In the lithium source three-dimensional framework 1, a boron-nitrogen lithium ring ([B3N3Li3]n) and a crown ether (lithium complex) ([15-C-5-Li]k) are provided. Specific preparation method: Synthesis of boron-nitrogen lithium six-membered ring: Weigh high-purity lithium nitride and boron nitride powders in a 1:1 molar ratio, mix the two powders thoroughly and uniformly in a mortar or small ball mill, press the uniformly mixed powder into tablets, place them in a tube furnace, program the temperature to 750°C, and keep them at this temperature for 12 hours. The boron-nitrogen lithium ring can then be obtained. The preparation of the crown ether is the same as in Example A1. (3) Mix the lithium source core 2 and the lithium source three-dimensional framework 1 in a solvent to form a "lithium source-framework" complex. The specific steps are the same as in Example A1.

[0111] Steps S02, S03 and S04 are the same as in Example A1.

[0112] Example A3 An organic lithium supplement and its preparation method Organic lithium supplements include: The lithium source three-dimensional framework 1, lithium source core 2, free radical capturing molecule 4, and phospholipid bimolecular coating layer 5 are all the same as in Example A1.

[0113] Voltage-sensitive molecule 3 (perylene diimide) is chemically grafted onto the three-dimensional framework 1 of the lithium source; and it surrounds the core 2 of the lithium source through π-π stacking.

[0114] Preparation methods include: Step S01 is the same as in Example A1.

[0115] In step S02, a voltage-sensitive molecule 3 precursor is provided. The “lithium source-backbone” complex and the voltage-sensitive molecule 3 precursor are mixed in a solvent and a grafting reaction is carried out to attach the voltage-sensitive molecule 3 to the lithium source three-dimensional framework 1. (1) Voltage-sensitive molecule 3 is selected from perylene diimide. The preparation methods of its precursor include: 1) Preparation of perylene tetracarboxylic dianhydride (PTCDA): 1 mol of perylene is dispersed or dissolved in molten base. Air or oxygen is introduced at 200°C, and the 3, 4, 9, 10-positions of perylene are oxidized to generate perylene tetracarboxylate. After the reaction is completed, the melt is dissolved in water and then acidified with 1 mol / L hydrochloric acid to precipitate perylene tetracarboxylic dianhydride (PTCDA). Then, it is purified by recrystallization in DMF solvent. 2) Condensation reaction of perylene tetracarboxylic dianhydride (PTCDA) with amine: In NMP, PTCDA, amine (usually in excess of 1.2-2 equivalents) and catalyst are mixed and heated under reflux. After the reaction is completed, the mixture is cooled, filtered, and the resulting solid is repeatedly washed with solvents such as methanol and water to remove excess amine, catalyst and solvent. Finally, it is purified by column chromatography, recrystallization or sublimation.

[0116] (2) Mix the “lithium source-backbone” complex and voltage-sensitive molecule 3 precursor in a solvent, and follow the same steps as step S02 in Example A1.

[0117] Steps S03 and S04 are the same as in Example A1.

[0118] Example A4 An organic lithium supplement and its preparation method The lithium source three-dimensional framework 1, lithium source core 2, voltage-sensitive molecule 3, and phospholipid bimolecular coating layer 5 are all the same as in Example A1.

[0119] Free radical scavenging molecule 4 (distearate phosphate) is covalently linked to voltage-sensitive molecule 3.

[0120] Preparation methods include: Steps S01 and S02 are the same as in Example A1. In step S03, a free radical scavenging molecule 4 is provided. First, a free radical scavenging molecule (distearate phosphate) is synthesized, and then it is grafted onto a voltage-sensitive molecule.

[0121] (1) A free radical scavenging molecule 4 (distearate phosphate) is provided. The preparation steps include: adding 1 mol of stearyl alcohol to a reaction vessel and heating it to 60°C to melt. Under vigorous stirring, 1 mol of phosphorus pentoxide powder is slowly added in batches. The temperature is controlled at 60-80°C. After the addition is complete, the temperature is raised to 80-100°C and the reaction is maintained for 3-6 hours until P2O5 is completely dissolved and the reaction tends to be complete. After the reaction is completed, a viscous paste or waxy product is directly obtained, which is distearate phosphate.

[0122] (2) Distearate phosphate-NDI covalent grafting, the preparation steps include: gradient film (1 g), diol-NDI (1 g), distearate phosphate (0.9 g), AIBN (0.1 g); ultraviolet light initiation grafting: under nitrogen protection, irradiate with 365 nm ultraviolet light for 1 h, AIBN initiates free radical reaction, the phosphate group of distearate phosphate forms POC covalent bond with the hydroxyl group of NDI; purification treatment: wash with ethanol to remove unreacted substances, vacuum dry at 60℃ for 12 hours.

[0123] Step S04 is the same as in Example A1.

[0124] Example A5 An organic lithium supplement and its preparation method Organic lithium supplements include: The lithium source three-dimensional framework 1, lithium source core 2, voltage-sensitive molecule 3, and phospholipid bimolecular coating layer 5 are all the same as in Example A1.

[0125] Free radical scavenging molecule 4 (dimyristicoyl phosphate) is covalently linked to voltage-sensitive molecule 3.

[0126] Preparation methods include: Steps S01 and S02 are the same as in Example A1. In step S03, a free radical scavenging molecule 4 is provided. First, a free radical scavenging molecule (dimyristicoyl phosphate) is synthesized, and then it is grafted onto a voltage-sensitive molecule.

[0127] (1) Provide radical scavenging molecule 4 (dimyristicoyl phosphate), the preparation steps include: 1) Dissolve 1 mol of 1,2-dimyristicoyl-sn-glycerol in 100 mL of anhydrous chloroform, add it to a four-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel and drying tube, and add a measured amount of anhydrous pyridine (usually in excess relative to POCl3). 2) Place the entire system in an ice-water bath and cool to 0-5°C. Under vigorous stirring, slowly add the POCl3 solution dissolved in anhydrous chloroform through the constant pressure dropping funnel. 3) Transfer the reaction mixture to water at 0°C for hydrolysis. After hydrolysis, continue stirring for 0.5-1 h. 4) Purification treatment: Wash the organic phase sequentially with dilute hydrochloric acid (to remove excess pyridine), saturated sodium bicarbonate solution and brine. After drying with anhydrous sodium sulfate, filter, remove the solvent under reduced pressure to obtain the crude product. The crude product is purified by column chromatography.

[0128] (2) Covalent grafting of dimyristic phosphate-NDI. The preparation steps include: gradient film (1g), diol-NDI (0.8g), dimyristic phosphate (0.7g), and AIBN (0.15g); UV-initiated grafting: under nitrogen protection, irradiated with 365nm UV light for 2 h, AIBN initiated free radical reaction, and the phosphate group of dimyristic phosphate formed a POC covalent bond with the hydroxyl group of NDI; purification treatment: washing with ethanol to remove unreacted substances, and vacuum drying at 60℃ for 12 h.

[0129] Step S04 is the same as in Example A1.

[0130] Example A6 An organic lithium supplement and its preparation method Organic lithium supplements include: The lithium source three-dimensional framework 1, lithium source core 2, voltage-sensitive molecule 3, and free radical capturing molecule 4 are all the same as in Example A1.

[0131] The thickness of the phospholipid bilayer 5 is changed to 8 nm, and the rest is the same as in Example A1.

[0132] Preparation methods include: Steps S01, S02 and S03 are the same as in Example A1.

[0133] In step S04, a phospholipid bilayer 5 is provided, which is connected to the lithium source core 2 via hydrogen bonds. Preparation method: 5g of organic lithium supplementation precursor and 0.15g of DOPC (C 44 H 84 NO8P and 10 mL of NMP were dispersed in the NMP solution, and a bilayer was induced by constant voltage at 1.5V.

[0134] Comparative Example A1 An organic lithium supplement and its preparation method It contains only the lithium source core (lithium 1,3,5-triazine phosphate) and no other components. Its preparation method is the same as in Example A1.

[0135] Comparative Example A2 An organic lithium supplement and its preparation method It contains only a lithium source core and a lithium source three-dimensional framework. The two components and their preparation methods are the same as in Example A1.

[0136] Comparative Example A3 An organic lithium supplement and its preparation method It contains only a lithium source core, a lithium source three-dimensional framework, and a voltage-sensitive molecule. The above three components and their preparation methods are the same as in Example A1.

[0137] Comparative Example A4 An organic lithium supplement and its preparation method It contains only a lithium source core, a lithium source three-dimensional framework, a voltage-sensitive molecule, and a free radical trapping molecule. The above four components and their preparation methods are the same as in Example A1.

[0138] Table 1

[0139] 2. Example of a lithium-ion battery: Examples B1 to B6 and Comparative Examples B1 to B4 each provide a lithium-ion battery. Each lithium-ion battery is assembled according to the following method: 1) Positive electrode plate: The positive electrode of the lithium-ion battery in Examples B1 to B6: In Examples B1 to B6, the positive electrode sheets of the lithium-ion batteries used the composite organic lithium-replenishing additives provided in Examples A1 to A6 as the positive electrode lithium-replenishing additives. Under the same conditions, the positive electrode material (NCM811), Super P conductive agent, PVDF binder, and positive electrode lithium-replenishing additives were mixed in an appropriate amount of NMP at a specific mass ratio (92:1.5:2:4.5) to prepare a positive electrode slurry. Subsequently, the positive electrode sheets were processed through homogenization, coating, drying, and cutting to complete the fabrication. Finally, the positive electrode sheets were baked in a 100°C vacuum oven to remove residual moisture.

[0140] 2) Negative Electrode Sheet: A negative electrode slurry is prepared by uniformly mixing graphite (the negative electrode active material), Super P (the conductive agent), carboxymethyl cellulose (CMC) (the thickener), and styrene-butadiene rubber (SBR) (the binder) in deionized water, wherein the mass ratio of graphite:Super P:CMC:SBR is 95:2:0.5:2.5. The negative electrode slurry is coated onto the current collector copper foil, and after drying-rolling-secondary drying processes, the negative electrode sheet is formed.

[0141] 3) Diaphragm: Polyethylene (PE) diaphragm is used.

[0142] 4) Electrolytes of lithium-ion batteries in Examples B1 to B6 and Comparative Examples B1 to B4: The electrolyte is a 1 mol / L LiPF6 solution, and the solvent is composed of EC (ethylene carbonate) and DEC (diethyl carbonate) in a volume ratio of 1:1. 5) Assembly of secondary batteries: The above-mentioned positive electrode, negative electrode, electrolyte and separator are assembled into a lithium-ion battery (soft pack battery) according to the lithium-ion battery assembly requirements.

[0143] Performance testing The following performance tests were performed on the assembled lithium-ion batteries of each embodiment and comparative example. The specific testing methods are as follows: (1) Initial Coulomb efficiency test Under a constant temperature of 25℃, the battery was placed in a voltage range of 2.0 V to 4.1 V. It was first charged with a 0.1 C current until the voltage reached 4.1 V, then charged at a constant voltage of 4.1 V until the current dropped to 0.01 C. The capacity at this point was recorded as C1. The battery was then allowed to rest for 5 minutes, and then discharged with a 0.1 C current until the voltage dropped to 2.0 V. The capacity at this discharge rate was recorded as D1. The initial cycle coulombic efficiency was calculated using the formula "Initial Coulombic Efficiency = D1 / C1".

[0144] (2) Capacity retention rate test The battery was subjected to its first charge-discharge cycle at a constant temperature of 25°C. First, it was charged at a constant current of 1C until the voltage reached the upper limit of 4.1V. Then, it was charged at a constant voltage until the current dropped to 0.05C. After resting for 5 minutes, it was discharged at a constant current of 1C until the voltage dropped to 2.0V. The discharge capacity at this point was recorded as the first cycle discharge capacity. Subsequently, the charge-discharge cycle was repeated continuously, and the capacity retention rate of the battery after 2000 cycles at 25°C was calculated using the formula: "Capacity retention rate after 2000 cycles = (Cycle discharge capacity at 2000th cycle / First cycle discharge capacity) × 100%".

[0145] (3) Full-cycle lithium replenishment test 1) Lithium replenishment capacity test: Under a constant temperature environment of 25℃, the lithium replenisher was first charged at a constant current of 0.1 C until the voltage reached 3.5V, then charged at a constant voltage of 3.5V until the current dropped to 0.01C, recorded as stage A. Then, it was charged at a constant current of 0.1C until the voltage reached 4.2V, then charged at a constant voltage of 4.2V until the current dropped to 0.01C, recorded as stage B. Then, it was charged at a constant current of 0.05C until the voltage reached 4.5V, then charged at a constant voltage of 4.5V until the current dropped to 0.01C, recorded as stage C. The specific capacity of the lithium replenisher in each stage (A, B, C) was calculated.

[0146] 2) High-Temperature Storage Gas Generation Test: 1. Carefully place the prepared 100% SOC battery into the constant-volume chamber. Ensure the battery does not violently collide with the inner wall of the chamber, and secure the leads (if any). 2. Strictly follow the operating procedures to seal the chamber cover, ensuring the sealing ring is intact. 3. At room temperature (T0, e.g., 25°C), wait for the pressure sensor reading to stabilize and record the initial pressure P0. Place the entire sealed chamber into a pre-set temperature constant-temperature oven, setting the test temperature to 60°C. The data recording system will automatically and continuously record the pressure P(t) and temperature T(t) within the chamber, allowing the test to proceed uninterrupted at high temperature until the preset storage time (28 days) is reached. After reaching the preset time, remove the chamber from the oven and allow it to cool naturally to room temperature at ambient temperature. When the chamber temperature has completely returned to room temperature, record the stable final pressure P. f 4. Calculate the gas production rate according to the formula. 3) DCR test: Perform a constant current discharge or charge on a battery with a fixed SOC for 30 seconds, and record the voltage (V1, V2) and current (I) at the beginning and end. The calculation formula is: R=|V1-V2| / I. Results Analysis The lithium-ion batteries in each embodiment and comparative example were subjected to relevant performance tests, and the results are shown in Table 2 below.

[0147] Table 2

[0148] As can be seen, Examples B1-B6 exhibited high lithium replenishment rates across all voltage ranges, with significantly higher initial coulombic efficiency and capacity retention than all comparative groups. Furthermore, they showed lower gas production and DC resistance (DCR) during high-temperature storage. This is attributed to the unique and well-designed composition and structure of the lithium replenishing agent. All five components (lithium source core, lithium source three-dimensional framework, voltage-sensitive molecule, free radical scavenging molecule, and phospholipid bilayer) played their respective roles, collectively enhancing the performance of the lithium replenishing agent.

[0149] Specifically, the high-temperature storage gas production and DCR of Example B1 were significantly lower than those of Comparative Example B4. The difference lies in the phospholipid bilayer. The phospholipid bilayer can better protect the lithium supplement and prevent it from undergoing side reactions with the electrolyte, thus resulting in superior high-temperature storage performance. In addition, the phospholipid bilayer can help form a more stable interface, with a higher internal lithium-ion migration rate, which helps reduce the DCR. This is further demonstrated in the comparison between Example B1 and Example B6. The phospholipid bilayer in Example B6 is thicker (8 nm), and the corresponding high-temperature storage gas production is lower than that in Example B1, while the DCR is slightly increased. This indicates that the amount of phospholipid bilayer needs to be just right, neither too thick nor too thin.

[0150] The difference between Comparative Examples B3 and B4 lies in the free radical scavenging molecules. Comparative Example B4 exhibits lower high-temperature storage gas generation and DCR than Comparative Example B4 because the free radical scavenging molecules can capture free radicals in the electrolyte, suppressing free radical-induced side reactions, thereby improving high-temperature storage stability and reducing battery internal resistance.

[0151] The difference between comparative examples B2 and B3 lies in the voltage-sensitive molecule. Comparative example B3 exhibits a significantly higher lithium replenishment capacity than comparative example B2 because the voltage-sensitive molecule can regulate the lithium source release process according to voltage changes, achieving full lithium release. Furthermore, due to the presence of the voltage-sensitive molecule, the capacity differences between the two are more pronounced in stages A, B, and C.

[0152] The difference between Comparative Examples B1 and B2 lies in the three-dimensional lithium source framework. It can be seen that the lithium replenishment capacity of Comparative Example B2 is higher than that of Comparative Example B1, and its initial coulombic efficiency and cycle stability are also better than those of Comparative Example B1. This is because the three-dimensional lithium source framework in Comparative Example B2 can provide a certain amount of lithium replenishment, and the introduction of the three-dimensional lithium source framework stabilizes and fixes the lithium source core, preventing the loss of lithium source and ensuring the continuity of lithium replenishment.

[0153] In summary, the organic lithium replenisher provided in this application embodiment has a lithium source core 2 firmly connected to the three-dimensional lithium source framework 1 by chemical bonds, while introducing voltage-sensitive molecules 3 grafted onto the framework and surrounding the lithium source core 2. This structural design ensures that the lithium source core 2 is stably fixed, preventing lithium loss during battery charging and discharging and ensuring continuous lithium replenishment. The accumulation of voltage-sensitive molecules 3 around the lithium source core 2 can regulate the lithium release process according to changes in battery voltage, achieving on-demand lithium replenishment and significantly improving the battery's charging and discharging efficiency and cycle stability. Furthermore, the entire system exhibits no transition metal dissolution, avoiding electrolyte oxidation and decomposition. This results in an organic lithium replenisher with high lithium content, controllable decomposition voltage, zero metal dissolution, and long-term structural stability, which is beneficial for widespread application.

[0154] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An organic lithium supplement, characterized in that, The organic lithium supplement includes: Three-dimensional framework of lithium source; The lithium source core is connected to the three-dimensional framework of the lithium source via chemical bonds; Voltage-sensitive molecules are chemically grafted onto the three-dimensional framework of the lithium source and stacked around the core of the lithium source.

2. The organic lithium supplement agent according to claim 1, characterized in that, The organic lithium supplement includes the following decomposition voltage: The decomposition voltage range for the first stage is 2.5-3.5V; The decomposition voltage range for the second stage is 3.5-4.2V; The decomposition voltage range for the third stage is greater than 4.2V.

3. The organic lithium supplement agent according to claim 1, characterized in that, The lithium source core comprises a lithium phosphate compound containing a six-membered ring, wherein the six-membered ring is composed of carbon, hydrogen, oxygen, or nitrogen; and / or, The molar ratio of the lithium source core to the lithium source three-dimensional framework is 1:(0.5~2); and / or, The voltage-sensitive molecule includes fused-ring imide compounds; and / or, The three-dimensional framework of the lithium source includes one or both of the following: lithium heterocycles containing oxygen or nitrogen, and lithium complexes.

4. The organic lithium supplement according to claim 3, characterized in that, The three-dimensional framework of the lithium source includes an oxygen- or nitrogen-containing lithium heterocycle and a lithium complex, and the molar ratio of the oxygen- or nitrogen-containing lithium heterocycle to the lithium complex is 1:(0.3~3).

5. The organic lithium supplement according to claim 4, characterized in that, The oxygen- or nitrogen-containing lithium heterocycle and the lithium complex are interconnected by hydrogen bonds, and / or, The lithium source core is covalently connected to the oxygen- or nitrogen-containing lithium heterocycle, with a binding energy of 3.5~4.9 eV; and / or, The lithium source core is connected to the lithium complex via non-covalent bonds, with a binding energy of 1.2~2.3 eV.

6. The organic lithium supplement according to claim 1, characterized in that, The organic lithium supplement also includes a free radical scavenging molecule, which is covalently linked to the voltage-sensitive molecule.

7. The organic lithium supplement according to claim 1, characterized in that, The phospholipid groups on the surface of the lithium source core are bonded to phosphorus-containing molecules through phosphorus-oxygen bonds between phosphate groups, forming a directionally arranged phospholipid bimolecular coating layer. The phospholipid bimolecular coating layer is connected to the lithium source core through hydrogen bonds.

8. The organic lithium supplement according to claim 7, characterized in that, The thickness of the phospholipid bilayer is 5-8 nm.

9. A method for preparing an organic lithium supplement as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The lithium source core and the lithium source three-dimensional framework are mixed and reacted in a solvent to form a "lithium source-framework" composite. A voltage-sensitive molecule precursor is provided. The "lithium source-backbone" complex and the voltage-sensitive molecule precursor are mixed in a solvent and a grafting reaction is carried out to attach the voltage-sensitive molecule to the three-dimensional lithium source backbone to obtain an organic lithium supplement.

10. A secondary battery, characterized in that, The device includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode comprises the organic lithium supplement agent according to any one of claims 1 to 8 or the organic lithium supplement agent prepared by the preparation method according to claim 9; or, the electrolyte comprises the organic lithium supplement agent according to any one of claims 1 to 8 or the organic lithium supplement agent prepared by the preparation method according to claim 9.

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