Organic functional self-assembly materials, preparation method, application, modified lithium negative electrode and lithium metal battery

Abstract

The application belongs to the field of energy storage materials, and particularly relates to an organic functional self-assembled material, a preparation method, application, a modified lithium negative electrode and a lithium metal battery, wherein the organic functional self-assembled material is a two-dimensional rod-like material with at least one crystal plane of 020, 400 or 022 formed by self-assembly of a compound of formula 1. Researches show that the organic functional self-assembled material can effectively alleviate defects such as dendrite, interface instability and large volume change of metal lithium in the cycle process, can significantly optimize the long-range cycle performance of metal lithium, can still obtain excellent long cycle stability at a high rate, and is suitable for preparing super-fast-charging metal lithium batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery materials, specifically relating to the field of modified lithium anodes for lithium metal batteries. Background Technology

[0002] With the rapid development of high-energy-density energy storage devices, lithium metal has become increasingly popular due to its extremely high theoretical specific capacity (3860 mAh·g). -1 With its low energy density and low electrochemical potential (-3.04 V vs. SHE), lithium metal is considered an ideal anode material for next-generation high-energy-density batteries. However, lithium metal is prone to dendrite growth and volume expansion during charge-discharge cycles, leading to interface instability, electrolyte decomposition, and serious safety hazards. These problems limit the commercialization of lithium metal batteries in practical applications.

[0003] Common strategies for modifying lithium metal anodes include constructing artificial solid-state electrolyte interfaces, surface coating modification, and introducing functional fillers to regulate ion distribution and deposition morphology. Among these, the chemical structure and polarity characteristics of the functional fillers play a decisive role in lithium-ion flux distribution and interfacial stability. While traditional inorganic fillers (such as Al₂O₃, TiO₂, and BaTiO₃) can improve mechanical stability, they have poor chemical compatibility with lithium metal and high interfacial resistance. Although organic covalent frameworks (COFs) or metal-organic frameworks (MOFs) possess tunable pore structures, their synthesis is complex and their stability is limited. Summary of the Invention

[0004] To address the problems existing in the prior art, the primary objective of this invention is to provide an organic functional self-assembly material, which aims to improve the lithium anode interface, suppress dendrite formation, and improve the long-range cycling stability of lithium metal.

[0005] The second objective of this invention is to provide a method for preparing the aforementioned organic functional self-assembly material and its application in the modification of lithium metal.

[0006] A third objective of this invention is to provide a lithium metal battery comprising the aforementioned organic functional self-assembly material and a modified lithium metal anode thereof.

[0007] An organic functional self-assembly material is a two-dimensional rod-shaped material with at least one crystal facet among 020, 400, and 022 formed by the self-assembly of a compound of Formula 1.

[0008] Formula 1.

[0009] The research of this invention shows that the organic functional self-assembled material can effectively alleviate the defects of lithium metal such as dendrite formation, interface instability and large volume change during cycling, and can significantly optimize the long-range cycling performance of lithium metal. It can still obtain excellent long-term cycling stability at high rates and is suitable for preparing super-fast charging lithium metal batteries.

[0010] Preferably, the organic functional self-assembly material is a two-dimensional rod-shaped material with an O20 crystal plane.

[0011] Research shows that organic functional self-assembly materials with 020 crystal planes can unexpectedly and significantly enhance the long-range cycle stability of lithium metal batteries.

[0012] The present invention also provides a method for preparing the organic functional self-assembled material, wherein the compound of Formula 1 is pre-dissolved in a water-soluble solvent to obtain a homogeneous mixed solution, which is then mixed with water for self-assembly, followed by solid-liquid separation to obtain the organic functional self-assembled material.

[0013] This invention demonstrates that the type of water-soluble solvent significantly affects the crystal structure of self-assembled materials, thereby influencing their electrochemical performance in lithium metal.

[0014] In this invention, the water-soluble solvent is at least one of THF, C1-C3 monohydric alcohols, and C2-C4 dihydric alcohols; preferably at least one of THF, methanol, and ethylene glycol.

[0015] In this invention, the water-soluble solvent is THF, and the organic functional self-assembled material with 022 crystal plane is obtained through self-assembly.

[0016] Alternatively, the water-soluble solvent is a monohydric alcohol, which self-assembles to obtain an organic functional self-assembled material with 400 crystal faces;

[0017] Alternatively, the water-soluble solvent is a diol, which self-assembles to obtain an organic functional self-assembled material with a 020 crystal plane.

[0018] In a homogeneous mixed solution, the concentration of compound of formula 1 is 5~10 mg / mL;

[0019] The volume ratio of water-soluble solvent to water is 1:2~6; more specifically, it can be 1:2.5~4.5.

[0020] The temperature for the self-assembly process is 10~40℃, and can be further reduced to 15~25℃;

[0021] The self-assembly process is performed under ultrasound.

[0022] The self-assembly time is 10-40 minutes, and can be further extended to 20-35 minutes.

[0023] This invention also provides an application of an organic functional self-assembly material, which is used as an interface material and composited on the surface of metallic lithium to prepare a modified lithium anode. The organic functional self-assembly material is the organic functional self-assembly material described in this invention.

[0024] In a further application, the modified lithium anode is assembled to prepare a lithium metal battery.

[0025] The present invention also provides a modified lithium anode, comprising lithium metal and a modified interface layer composite thereon on its surface, the modified interface layer comprising the organic functional self-assembly material described in the present invention.

[0026] In this invention, the modified interface layer formed on lithium metal can effectively adjust the lithium-ion deposition morphology, reduce interface impedance, suppress dendrite growth, and significantly improve the cycle stability and safety of the battery.

[0027] Preferably, the lithium metal is lithium foil, or it includes a support material and lithium metal incorporated within the support material. The support material can be a conventional copper foil material.

[0028] The lithium metal is either elemental or a lithium-containing alloy.

[0029] The present invention also provides a method for preparing the modified lithium anode, wherein a slurry containing an organic functional self-assembling material is composited on the surface of lithium metal to obtain the modified lithium anode.

[0030] The slurry contains a dispersant;

[0031] Preferably, the dispersant includes at least one of vegetable oil and mineral oil;

[0032] Preferably, the vegetable oil includes at least one of flaxseed oil, sunflower seed oil, or castor oil;

[0033] Preferably, the slurry contains 1-10 wt% organic functional self-assembly material.

[0034] Preferably, the composite method is roll forming;

[0035] Preferably, the rolling pressure is 1~5 MPa and the rolling speed is 10~50 mm·s. -1 The rolling temperature is 25~60℃.

[0036] The present invention also provides a lithium metal battery comprising the organic functional self-assembly material described herein.

[0037] Furthermore, the lithium metal battery includes the modified lithium anode described in this invention.

[0038] The lithium metal battery of the present invention, except for the modified lithium anode described in the present invention, may have other known components and structural parts.

[0039] Beneficial effects

[0040] This invention provides a novel organic functional self-assembly material, and studies have found that it can effectively alleviate defects of lithium metal during cycling, such as dendrite formation, interfacial instability, and large volume changes, and can significantly optimize the fast charging and long-range cycling performance of lithium metal.

[0041] The present invention also shows that the assembly method described above, especially the auxiliary assembly using diols, can further facilitate the acquisition of materials with the 020 dominant crystal plane and exhibiting excellent long-cycle stability in lithium metal batteries. Attached Figure Description

[0042] Figure 1 The images shown are SEM images of the self-assembled materials prepared in Examples 1 to 3, wherein (a) is an SEM image of modified material A prepared in Example 1; (b) is an SEM image of modified material C prepared in Example 2; and (c) is an SEM image of modified material B prepared in Example 3.

[0043] Figure 2 The graph shows the cycle performance of batteries in Examples 1-3 at 10C. Detailed Implementation

[0044] Example 1 (also known as Case 1): Preparation of lithium metal anode modified with filler A

[0045] Step 1: Preparation of Modified Material A Filler

[0046] Weigh out 80 mg of Formula 1 and dissolve it in 10 mL of tetrahydrofuran (THF) to form a purple solution;

[0047] The solution was slowly added dropwise to 40 mL of deionized water using a burette at a constant speed of 700 r·min. -1 Stir; sonicate the mixture at 15°C for 30 minutes (45 kHz, 500 W); then separate the solid and liquid phases, and vacuum dry at 60°C overnight. Collect the dried powder and label it as modified material A. Organic functional self-assembled material with 022 crystal plane is obtained.

[0048] Step 2: Slurry preparation

[0049] The modified material A filler is uniformly dispersed in mineral oil and thoroughly mixed by magnetic stirring to prepare a modified slurry.

[0050] Step 3: Preparation of modified lithium metal anode

[0051] The slurry is coated onto the surface of a roller press, and a continuous rolling process is used to bond the slurry to a copper-supported lithium metal foil (including the copper foil substrate and the lithium foil laminated on its surface) (the slurry is laminated onto the lithium foil surface). The rolling pressure is 3 MPa and the speed is 20 mm·s. -1 The temperature is 40℃, and the material is rolled and dried to obtain modified lithium metal anode material A.

[0052] Example 2 (also known as Case 2): Preparation of lithium metal anode modified with modified material C filler

[0053] Compared with Example 1, the only difference is that ethylene glycol is used to replace the THF by an equal volume; all other operations and parameters are the same as in Example 1. Organic functional self-assembled materials with 020 crystal planes are obtained.

[0054] Example 3 (also known as Case 3): Preparation of lithium metal anode modified with modified material B filler

[0055] Compared with Example 1, the only difference is that methanol was used to replace the THF by an equal volume; all other operations and parameters are the same as in Example 1. An organic functional self-assembled material with 400 crystal planes was obtained.

[0056] Example 4:

[0057] Compared to Example 2, the only difference is that in step 1, the concentration of the purple solution (Formula 1) is 5 mg / mL, the added water is 3 times the volume of ethylene glycol, and the stirring speed is 600 r·min. -1 Stir; sonicate the mixture at 20°C for 25 minutes; other operations and parameters are the same as in Example 1.

[0058] Performance Characterization and Comparison

[0059] The lithium metal batteries prepared according to the methods of Examples 1, 2, and 3 used common commercial electrolytes (ethylene carbonate (EC): 30 wt.%; propylene carbonate (PC): 20 wt.%; diethyl carbonate (DEC): 20 wt.%; dimethyl carbonate (DMC): 20 wt.%; lithium salt (LiPF6): 10 wt.%), and lithium iron phosphate as the positive electrode (LFP:PVDF:carbon black weight ratio of 8:1:1; LFP surface loading of 6 mg / cm³). -2 Modified lithium metal foil was used as the negative electrode to prepare the battery. The measured cycle performance of the battery at a test temperature of 30℃, a rate of 10 C, and a voltage range of 2.8~4.1V was as follows: Figure 2 As shown in the figure. It can be seen from the graph that the left side of the vertical axis represents the discharge capacity (mAh·g). -1 The right side represents the charge / discharge efficiency (%); the horizontal axis represents the number of cycles, ranging from 0 to 5000 cycles.

[0060] Specific performance: Discharge capacity: The lithium metal battery modified with material C has an initial discharge capacity of approximately 121 mAh·g. -1 As cycling continues, the capacity remains relatively stable, maintaining close to 112 mAh·g even after nearly 5000 cycles at 30°C and 10°C. -1 The battery exhibits excellent cycle stability. Charge / discharge efficiency: The curve remains consistently close to 93%, indicating minimal side reactions and very high coulombic efficiency during long cycles. Overall performance evaluation: This figure shows that the lithium metal anode modified with material C effectively suppresses interfacial side reactions during long cycles, ensuring capacity retention and high energy efficiency of the cathode, demonstrating excellent cycle stability and high coulombic efficiency. Furthermore, the material obtained in Example 4 exhibits similar performance to material C in Example 2, maintaining a capacity of approximately 111 mAh·g after 5000 cycles. -1 .

[0061] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. An application of an organic functional self-assembly material, characterized in that, It is used as an interface material and composited on the surface of metallic lithium to prepare a modified lithium anode. The modified lithium anode is then assembled to prepare a metallic lithium battery. The organic functional self-assembly material is a two-dimensional rod-shaped material with at least one of the crystal planes 020, 400, and 022, formed by the self-assembly of the compound of Formula 1. Formula 1; The preparation method of the organic functional self-assembly material is as follows: the compound of Formula 1 is pre-dissolved in a water-soluble solvent to obtain a homogeneous mixed solution, which is then mixed with water for self-assembly, followed by solid-liquid separation to obtain the organic functional self-assembly material. The water-soluble solvent is at least one of THF, C1-C3 monohydric alcohols, and C2-C4 dihydric alcohols; The volume ratio of water-soluble solvent to water is 1:2~6; The temperature during the self-assembly process is 10~40℃; The self-assembly process is carried out under ultrasound.

2. The application of the organic functional self-assembly material as described in claim 1, characterized in that, The water-soluble solvent is ethylene glycol.

3. The application of the organic functional self-assembly material as described in claim 1, characterized in that, The water-soluble solvent is THF, and the self-assembly yields an organic functional self-assembled material with a 022 crystal plane; Alternatively, the water-soluble solvent is a monohydric alcohol, which self-assembles to obtain an organic functional self-assembled material with 400 crystal faces; Alternatively, the water-soluble solvent is a diol, which self-assembles to obtain an organic functional self-assembled material with a 020 crystal plane.

4. The application of the organic functional self-assembly material as described in any one of claims 1 to 3, characterized in that, In a homogeneous mixed solution, the concentration of compound of formula 1 is 5~10 mg / mL; The self-assembly time is 10~40 min.

5. A modified lithium anode, comprising lithium metal and a modified interface layer composited thereon on its surface, characterized in that, The modified interface layer comprises the organic functional self-assembly material described in any one of claims 1 to 4.

6. A method for preparing the modified lithium anode according to claim 5, characterized in that, The modified lithium anode is prepared by laminating a slurry containing organic functional self-assembling materials onto the surface of lithium metal.

7. The method for preparing the modified lithium anode as described in claim 6, characterized in that, The slurry contains a dispersant; The dispersant includes at least one of vegetable oil and mineral oil; The slurry contains 1-10 wt% organic functional self-assembly material. The composite process is described as roller pressing; The rolling pressure is 1~5 MPa, and the rolling speed is 10~50 mm·s. -1 The rolling temperature is 25~60°C.

8. A lithium metal battery, characterized in that, It includes the organic functional self-assembly material described in any one of claims 1 to 4.

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