A polymer binder, a physicochemically cross-linked conductive polymeric network, its preparation method and application

Abstract

This invention discloses a polymer binder, a physically-chemically dual-crosslinked conductive polymeric network, its preparation method, and its applications. The invention first discloses the polymer binder and its preparation method, comprising: dissolving polyacrylic acid and tannic acid in N-methylpyrrolidone to obtain a clear, pale yellow solution; adding a rubber containing carboxyl groups and stirring to obtain a suspension; filtering, evaporating, and drying to obtain the final product. The invention further discloses the preparation method and applications of the physically-chemically dual-crosslinked conductive polymeric network. This invention obtains a highly elastic polymer binder rich in catechol groups through a polymer blending and crosslinking process, characterized by multiple physically crosslinked layers. During electrode drying, a novel physically-chemically dual-crosslinked three-dimensional conductive polymeric network is constructed using the amidation reaction of the polymer binder and aminated carbon nanotubes, exhibiting excellent mechanical properties and energy dissipation capabilities, enabling the application of micron-sized silicon or SiO₂. x The negative electrode still exhibits excellent cycle stability under high load.

Description

Technical Field

[0001] This invention relates to the field of high-capacity negative electrode materials for lithium-ion batteries. More specifically, it relates to a polymer binder, a physically-chemically cross-linked conductive polymer network, its preparation method, and its applications. Background Technology

[0002] In recent years, the "range anxiety" of new energy vehicles and the "low battery anxiety" of 3C consumer electronics have highlighted the urgent need to develop high-energy-density lithium-ion batteries. Silicon (Si), due to its high theoretical capacity, abundant natural reserves, and environmental friendliness, has been considered a next-generation anode material for achieving high-performance lithium-ion batteries. However, the volume of Si undergoes a significant change (~400%) during charge and discharge, leading to problems such as Si particle breakage or pulverization, electrode structure collapse, and loss of electrical contact due to electrode material detachment, hindering the large-scale application of silicon materials. Furthermore, the enormous stress generated by the silicon-lithium alloying reaction can cause the solid electrolyte interface (SEI) to crack and repeatedly form, resulting in battery performance far below commercial standards. Developing high-performance binders with simple synthesis processes is considered a simple and effective strategy to alleviate silicon volume expansion.

[0003] Binders, acting as a bridge between conductive agents and Si particles, play an indispensable role in dissipating undesirable mechanical stress and maintaining the integrity of the electrode structure during cycling. However, traditional binders such as polyvinylidene fluoride (PVDF) and carboxymethyl cellulose (CMC) cannot adapt to the volume expansion of Si due to poor intermolecular interactions and their brittle nature. Binders with different polar groups (hydroxyl, catechol, carboxylates, and amino groups) can enhance their adhesion to Si particles through covalent bonds and / or enhanced van der Waals interactions. Furthermore, based on different polar interactions in binders, novel binders with self-healing capabilities, host-guest interactions, multiple crosslinking effects, and energy dissipation capabilities can be designed and prepared. Most of the aforementioned binders are used in nano-silicon anodes, exhibiting excellent mechanical properties and electrochemical stability. Micron-sized silicon anodes experience more severe stress damage during charge and discharge; therefore, a novel physical-chemical double-crosslinked conductive polymer network needs to be designed to fundamentally solve many problems existing in micron-sized silicon-based anodes. Summary of the Invention

[0004] One objective of this invention is to provide a polymer binder PTBR, its preparation method, and its application. PTBR not only has excellent deformability, but the double cross-linked three-dimensional conductive polymer network it forms also has excellent mechanical properties. When applied to silicon-based anodes, it exhibits stable long-cycle performance.

[0005] Another object of the present invention is to provide a physically-chemically cross-linked conductive polymeric network prepared by the above-mentioned polymer binder and its application. The physically-chemically cross-linked conductive polymeric network has high strength and high toughness, and can buffer large volume expansion through the gradual pyrolysis of dynamic physical cross-linking formed by the slippage of rubber segments and multiple hydrogen bonds. It can be used in silicon-based anodes (micron-sized silicon and SiO2). x (etc.) and other high-capacity, large-volume-expansion electrode materials to prepare high-energy-density lithium-ion batteries.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention first provides a method for preparing a polymer adhesive, comprising the following steps:

[0008] A clear, pale yellow solution was obtained by dissolving a high molecular weight polymer containing carboxyl groups and tannic acid in N-methylpyrrolidone.

[0009] After adding carboxyl-containing rubber to the clear, pale yellow solution and stirring, a suspension is obtained.

[0010] The suspension was filtered, evaporated, and dried to obtain a polymer binder, namely PTBR.

[0011] Furthermore, the mass ratio of the carboxyl-containing polymer to tannic acid is 2:1 to 5:1.

[0012] Furthermore, the mass ratio of the carboxyl-containing polymer to the carboxyl-containing rubber is 2:1 to 5:1.

[0013] Furthermore, the carboxyl-containing polymer is one or more of polyacrylic acid and sodium polyacrylate.

[0014] Furthermore, the rubber containing carboxyl groups is one or more of carboxybutadiene rubber, carboxystyrene-butadiene rubber, and carboxynitrile rubber.

[0015] Furthermore, the stirring is first carried out at a low temperature of 80-100℃ for 8-12 hours to ensure that the carboxylated nitrile rubber is fully dissolved, and then the temperature is raised to 150-160℃ and stirring is continued for 2-3 hours.

[0016] Furthermore, the filtration is hot filtration. Since rubber containing carboxyl groups is less soluble in N-methylpyrrolidone, the suspension is filtered while hot, such as by vacuum filtration or natural filtration, to separate the undissolved rubber containing carboxyl groups.

[0017] Furthermore, the evaporation involves rotary evaporating the filtered liquid at 100-120°C to remove most of the N-methylpyrrolidone.

[0018] Furthermore, the drying process is carried out under vacuum at 100-120°C until the product is completely dry.

[0019] The polymer binder prepared by the above method is also within the scope of protection of this invention.

[0020] This invention further provides the above-mentioned polymer binder for the preparation of physicochemically cross-linked conductive polymeric networks and / or micron-sized silicon and / or SiO2 for lithium-ion batteries. x Applications on the negative electrode.

[0021] This invention provides a method for preparing a physically-chemically cross-linked conductive polymeric network, comprising the following steps:

[0022] The above-mentioned polymer binder was formulated into a polymer binder solution. The polymer binder solution was mixed evenly with aminated carbon nanotubes. By means of the amidation reaction between the polymer binder and the aminated carbon nanotubes during the drying process, a physical-chemical double cross-linked three-dimensional conductive polymer network was synthesized.

[0023] Furthermore, the aminated carbon nanotubes are one type of aminated single-walled carbon nanotubes and aminated multi-walled carbon nanotubes.

[0024] Furthermore, the concentration of the polymer binder solution is 20-40 mg / mL. -1 .

[0025] Furthermore, the mass ratio of the aminated carbon nanotubes to the polymer binder is 1:1 to 1:2.

[0026] Furthermore, the amidation reaction between the polymer binder and the aminated carbon nanotubes during the drying process is carried out under vacuum at 120-180°C for 2-3 hours.

[0027] The physical-chemical double-crosslinked conductive polymer network prepared by the above method is also within the scope of protection of this invention.

[0028] This invention further provides the above-mentioned physical-chemical double-crosslinked conductive polymer network for the preparation of micron-sized silicon and / or SiO2. x Applications in negative electrodes or lithium-ion batteries.

[0029] This invention provides a lithium-ion battery micron-sized silicon and / or SiO2. x The method for preparing the negative electrode includes the following steps:

[0030] The above-mentioned polymer binder is formulated into a polymer binder solution, and a slurry coating process is used to coat micron-sized silicon or SiO2. xA polymer binder solution is mixed with aminated carbon nanotubes and coated onto copper foil. During the drying process, the polymer binder undergoes an amidation reaction with the aminated carbon nanotubes to synthesize a physically-chemically cross-linked conductive polymeric network of micron-sized silicon or SiO₂. x Composite electrodes, namely micron-sized silicon and / or SiO2 for lithium-ion batteries. x negative electrode.

[0031] Furthermore, the aminated carbon nanotubes are one type of aminated single-walled carbon nanotubes and aminated multi-walled carbon nanotubes.

[0032] Furthermore, the concentration of the polymer binder solution is 20-40 mg / mL. -1 .

[0033] Furthermore, the mass ratio of the aminated carbon nanotubes to the polymer binder is 1:1 to 1:2; the aminated carbon nanotubes are bonded to micron-sized silicon or SiO2. x The mass ratio is 1:7 to 1:8.

[0034] Furthermore, the amidation reaction between the polymer binder and the aminated carbon nanotubes during the drying process is carried out under vacuum at 120-180°C for 2-3 hours.

[0035] The lithium-ion battery micron-sized silicon and / or SiO2 prepared by the above method x The negative electrode is also within the scope of protection of this invention.

[0036] To address the issues of localized stress concentration and interfacial instability in micron-sized silicon-based anodes, a novel stress-dissipating unit was introduced to construct a novel physical-chemical dual-crosslinked conductive polymer network. This design provides a robust three-dimensional conductive network through chemical crosslinking; simultaneously, the multiple physical crosslinks increase the degree of crosslinking and the binding sites with silicon particles, improving mechanical properties. This physical-chemical dual-crosslinked conductive polymer network exhibits excellent mechanical properties, resulting in the highest load (2.337 mN), hardness (0.0765 GPa), modulus (1.45 GPa), and elastic recovery (43.93%) of the micron-sized silicon-based anode at an indentation depth of ~1000 nm. The prepared μSi / PTBR electrode was tested at 0.6 Ag... -1 With 2Ag -1 It exhibited excellent cyclic performance at all levels, and at 1.103 mg cm⁻¹ -2 With Si loading at 0.6Ag -1 It retains a capacity retention of up to ~90.3% after 50 cycles at current density. This physical-chemical dual crosslinked polymer network was applied to SiO2. x The negative electrode can also achieve excellent long-cycle performance.

[0037] The beneficial effects of this invention are as follows:

[0038] This invention prepares a highly elastic polymer binder (PTBR) rich in catechol groups through a simple polymer blending and crosslinking process, characterized by multiple physical crosslinking. During electrode drying, the conductive agent and binder are chemically crosslinked via an amidation reaction of PTBR and aminated carbon nanotubes (SCNT-NH2), constructing a novel physical-chemical dual crosslinked three-dimensional conductive polymer network (PTBR-SCNT-NH2). PTBR-SCNT-NH2 combines the high strength of polyacrylic acid with the high toughness of carboxylated nitrile rubber, exhibiting excellent mechanical properties and energy dissipation capabilities, making it suitable for silicon-based (micron-sized silicon or SiO2) applications. x The negative electrode still exhibits excellent cycle stability under high load, enabling the fabrication of high-energy-density lithium-ion batteries.

[0039] This invention provides rich and intuitive experience for designing and constructing efficient stress-dissipating polymer binders and conductive polymer networks for use in silicon-based anodes of lithium-ion batteries and other high-capacity anodes with large volume expansion. Attached Figure Description

[0040] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0041] Figure 1 This is a schematic diagram of the chemical structure of the physical-chemical double crosslinked conductive polymer network (PTBR-SCNT-NH2) formed in Examples 4 and 5.

[0042] Figure 2 (a) shows the infrared spectra of the polymer binders (PTBR, PT, PBR and TBR) prepared in Example 1 and Comparative Examples 1-3; (b) shows the infrared fitted spectra of PTBR at 30, 90 and 150 °C in Examples 4 and 5; and (c) shows the high-resolution N element XPS spectra of the single physical / chemical double crosslinked conductive polymer network (XNBR-SCNT-NH2, TA-SCNT-NH2 and PAA-SCNT-NH2) in Comparative Examples 4-6.

[0043] Figure 3 The mechanical properties of the polymer binders (PTBR and PT) in Example 1 and Comparative Example 2 are shown, wherein (a) is the tensile stress-strain curve of the polymer binders (PTBR and PT) in Example 1 and Comparative Example 2, and (b) is the stress-strain curve of the PTBR in Example 1 under cyclic tensile test.

[0044] Figure 4The mechanical properties of the composite electrodes prepared in Example 6 and Comparative Examples 1-3 are shown, wherein (a) is the load-displacement curve of the electrodes in Example 6 and Comparative Examples 1-3, and (b) and (c) are the modulus, hardness and elastic recovery calculated from the load-displacement curve, respectively.

[0045] Figure 5 The figures show the electrochemical performance of the composite electrodes in Example 6 and Comparative Examples 1-3; where (a), (b), and (d) are the first charge-discharge curves and the 0.6Ag half-cell electrochemical curves of the composite electrodes in Example 6 and Comparative Examples 1-3, respectively. -1 and 2Ag -1 Cyclic performance diagrams at current densities, (c) shows the cycling performance of the μSi / PTBR electrode under different Si loads in Example 6.

[0046] Figure 6 The graphs show the half-cell electrochemical performance of the composite electrodes prepared in Example 7 and Comparative Example 7. (a) shows the performance of SiO2. x / PTBR and SiO x The first charge-discharge curve of / PAA, (b) is SiO x / PTBR and SiO x / PAA electrode long-cycle performance diagram.

[0047] Figure 7 The figures show the electrochemical performance of the full cell assembled with μSi / PTBR and a commercial lithium-ion ternary cathode in Example 6. (a) and (b) are the charge-discharge curve and cycle performance of the full cell, respectively. Detailed Implementation

[0048] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1: Preparation of the polymer binder PTBR

[0050] (1) Weigh 2.0g of polyacrylic acid and 1.0g of tannic acid and dissolve them in N-methylpyrrolidone to obtain a clear pale yellow solution;

[0051] (2) Add 1.0g of carboxylated acrylonitrile butadiene rubber (XNBR) to a clear, pale yellow solution and stir at a low temperature of 100℃ for 8h. Then, raise the temperature to 150℃ and stir for 3h to obtain a suspension.

[0052] (3) The suspension was filtered naturally while hot, and after being evaporated at 100°C by rotary evaporation, it was placed at 120°C for vacuum drying overnight to obtain dark brown polymer binder PTBR.

[0053] Example 2: Preparation of the polymer binder PTBR

[0054] (1) Weigh 5.0g of sodium polyacrylate and 1.0g of tannic acid and dissolve them in N-methylpyrrolidone to obtain a clear pale yellow solution;

[0055] (2) Add 1.0g of carboxylated styrene-butadiene rubber to a clear, pale yellow solution and stir at low temperature in an oil bath at 80℃ for 12h. Then raise the temperature to 160℃ and stir for 2h to obtain a suspension.

[0056] (3) The suspension was filtered naturally while hot, and after being evaporated at 120°C by rotary evaporation, it was placed at 100°C for vacuum drying overnight to obtain dark brown polymer binder PTBR.

[0057] Example 3: Preparation of the polymer binder PTBR

[0058] (1) Weigh 2.0g of polyacrylic acid and 1.0g of tannic acid and dissolve them in N-methylpyrrolidone to obtain a clear pale yellow solution;

[0059] (2) Add 0.5g of carboxybutadiene rubber to a clear, pale yellow solution and stir at low temperature in an oil bath at 100℃ for 8 hours. Then, raise the temperature to 150℃ and stir for 3 hours to obtain a suspension.

[0060] (3) The suspension was filtered naturally while hot, and after being evaporated at 100°C by rotary evaporation, it was placed at 120°C for vacuum drying overnight to obtain dark brown polymer binder PTBR.

[0061] Example 4: Preparation of a Physical-Chemical Double-Crossed Three-Dimensional Conductive Polymer Network for Micron-Symbol Silicon Anodes

[0062] The polymer binder PTBR prepared in Example 1 was formulated into a 30 mg / mL solution. -1 A PTBR solution was prepared by mixing PTBR solution with aminated single-walled carbon nanotubes (SCNT-NH2) (PTBR to SCNT-NH2 mass ratio of 2:1) and then vacuum-drying at 150℃ for 3 h to synthesize a physicochemically cross-linked three-dimensional conductive polymeric network (PTBR-SCNT-NH2). The schematic diagram of its chemical structure is shown below. Figure 1 As shown, this double-crosslinked conductive polymer network consists of two parts: a chemically crosslinked three-dimensional conductive polymer network and stress-dissipating units formed by multiple physical crosslinks. The chemical crosslinking achieves chemical bonding between the conductive agent and the binder through the formed amide bonds, providing a robust conductive network for the micron-sized Si particles. The stress-dissipating units with multiple physical crosslinks can buffer the severe stress generated by Si expansion through the slippage of folded molecular chains in the rubber and the stepwise cleavage of hierarchical hydrogen bonds.

[0063] Example 5 for SiO xPreparation of a physical-chemical double-crosslinked three-dimensional conductive polymeric network for the negative electrode

[0064] The polymer binder PTBR prepared in Example 3 was formulated into a 40 mg / mL solution. -1 A physical-chemical double crosslinked three-dimensional conductive polymer network can also be synthesized by mixing a PTBR solution with aminated multi-walled carbon nanotubes (PTBR to SCNT-NH2 mass ratio of 1:1) and drying under vacuum at 180℃ for 2 hours.

[0065] Example 6: Preparation of a physical-chemical double-crosslinked three-dimensional conductive polymer network micron-sized silicon composite electrode

[0066] The polymer binder PTBR prepared in Example 1 was formulated into a 30 mg / mL solution. -1 The PTBR solution was prepared by a slurry coating process. Micron-sized silicon powder, PTBR solution and SCNT-NH2 (the mass ratio of micron-sized silicon powder, PTBR and SCNT-NH2 is 7:2:1) were mixed evenly and coated onto copper foil. The mixture was then vacuum dried at 150℃ for 3 hours to synthesize a physical-chemical double cross-linked three-dimensional conductive polymer network micron-sized silicon composite electrode (μSi / PTBR), which is the micron-sized silicon anode for lithium-ion batteries.

[0067] Example 7: Physical-chemical dual-crosslinked three-dimensional conductive polymer network SiO x Preparation of composite electrodes

[0068] The polymer binder PTBR prepared in Example 3 was formulated into a 20 mg / mL solution. -1 The PTBR solution uses a slurry coating process to coat SiO2. x Powder, PTBR solution and SCNT-NH2(SiO) x The powder, PTBR, and SCNT-NH2 (in a mass ratio of 8:1:1) were mixed evenly and coated onto copper foil. The mixture was then vacuum-dried at 180°C for 2 hours to synthesize a physically-chemically cross-linked three-dimensional conductive polymeric network SiO2. x Composite electrode (SiO) x / PTBR), namely lithium-ion battery SiO x negative electrode.

[0069] Comparative Example 1

[0070] (1) Weigh 2.0g of polyacrylic acid and dissolve it in N-methylpyrrolidone to obtain a clear solution;

[0071] (2) Add 1.0g of carboxylated butadiene-acrylonitrile rubber to the clear solution and stir at low temperature in an oil bath at 100℃ for 8h, then raise the temperature to 150℃ and stir for 3h to obtain a suspension;

[0072] (3) The suspension was filtered naturally while hot, and after being evaporated by rotary evaporation at 100°C, it was placed in a vacuum dryer at 120°C overnight to obtain the polymer binder PBR.

[0073] (4) Prepare PBR to a 30 mg / mL solution. -1 The PBR solution was prepared by a slurry coating process. Micron-sized silicon powder, PBR solution and SCNT-NH2 (mass ratio of micron-sized silicon powder, PBR and SCNT-NH2 is 7:2:1) were mixed evenly and coated onto copper foil. The mixture was then vacuum dried at 150℃ for 3 hours to synthesize a micron-sized silicon composite electrode (μSi / PBR).

[0074] Comparative Example 2

[0075] (1) Weigh 2.0g of polyacrylic acid and 1.0g of tannic acid and dissolve them in N-methylpyrrolidone to obtain a clear pale yellow solution;

[0076] (2) Place the clear, pale yellow solution in a 100°C oil bath and stir at low temperature for 8 hours, then raise the temperature to 150°C and stir for 3 hours to obtain a suspension.

[0077] (3) The suspension was filtered naturally while hot, and after being evaporated by rotary evaporation at 100°C, it was placed in a vacuum dryer at 120°C overnight to obtain polymer binder PT;

[0078] (4) Prepare PT to a concentration of 30 mg / mL. -1 The PT solution was prepared by a slurry coating process. Micron-sized silicon powder, PT solution and SCNT-NH2 (the mass ratio of micron-sized silicon powder, PT and SCNT-NH2 is 7:2:1) were mixed evenly and coated onto copper foil. The mixture was then vacuum dried at 150℃ for 3 hours to synthesize a micron-sized silicon composite electrode (μSi / PT).

[0079] Comparative Example 3

[0080] (1) Weigh 1.0g of tannic acid and dissolve it in N-methylpyrrolidone to obtain a clear pale yellow solution;

[0081] (2) Add 1.0g of carboxylated acrylonitrile rubber to a clear, pale yellow solution and stir at low temperature for 8h in an oil bath at 100℃. Then, raise the temperature to 150℃ and stir for 3h to obtain a suspension.

[0082] (3) The suspension was filtered naturally while hot, and after being evaporated by rotary evaporation at 100°C, it was placed in a vacuum dryer at 120°C overnight to obtain the polymer binder TBR.

[0083] (4) Prepare TBR to a 30 mg / mL solution. -1The TBR solution was prepared by a slurry coating process. Micron-sized silicon powder, TBR solution and SCNT-NH2 (the mass ratio of micron-sized silicon powder, TBR and SCNT-NH2 is 7:2:1) were mixed evenly and coated onto copper foil. The mixture was then vacuum dried at 150℃ for 3 hours to synthesize a micron-sized silicon composite electrode (μSi / TBR).

[0084] Comparative Example 4

[0085] (1) Weigh 1.0g of carboxylated acrylonitrile butadiene rubber (XNBR) into N-methylpyrrolidone and place it in an oil bath at 100℃ and stir at low temperature for 8h to obtain a suspension;

[0086] (2) Filter the suspension naturally while it is hot to obtain a pale yellow clear solution. Take 1 mL of the solution, dry it and calculate its solid content.

[0087] (3) Mix the pale yellow clear solution with aminated single-walled carbon nanotubes (SCNT-NH2) evenly (the mass ratio of XNBR to SCNT-NH2 is 2:1), and dry it under vacuum at 150℃ for 3h to obtain a chemically cross-linked three-dimensional conductive polymer network (XNBR-SCNT-NH2).

[0088] Comparative Example 5

[0089] (1) Weigh 1.0 g of tannic acid (TA) and dissolve it in N-methylpyrrolidone to obtain 30 mg / mL -1 Clear solution;

[0090] (2) The clarified solution was mixed with aminated single-walled carbon nanotubes (SCNT-NH2) (the mass ratio of TA to SCNT-NH2 was 2:1) and then vacuum dried at 150°C for 3 h to obtain a physically cross-linked three-dimensional conductive polymer network (TA-SCNT-NH2).

[0091] Comparative Example 6

[0092] (1) Weigh 2.0 g of polyacrylic acid (PAA) and dissolve it in N-methylpyrrolidone to obtain 30 mg / mL -1 Clear solution;

[0093] (2) The clarified solution was mixed with aminated single-walled carbon nanotubes (SCNT-NH2) (the mass ratio of PAA to SCNT-NH2 was 2:1) and then vacuum dried at 150°C for 3 h to obtain a chemically cross-linked three-dimensional conductive polymer network (PAA-SCNT-NH2).

[0094] Comparative Example 7

[0095] (1) Weigh 2.0g of polyacrylic acid and dissolve it in N-methylpyrrolidone to obtain a clear solution;

[0096] (2) Place the clear solution in an 80℃ oil bath and stir at low temperature for 12 hours, then raise the temperature to 160℃ and stir for 2 hours to obtain a suspension.

[0097] (3) The suspension was filtered naturally while hot, and after being evaporated by rotary evaporation at 120°C, it was placed in a vacuum dryer at 100°C overnight to obtain the polymer binder PAA;

[0098] (4) Prepare PAA to a 30 mg / mL solution. -1 The PAA solution is prepared using a slurry coating process to coat SiO2. x Powder, PAA and SCNT-NH2(SiO) x The powder, PAA and SCNT-NH2 (in a mass ratio of 8:1:1) were mixed evenly and coated onto copper foil. The mixture was then vacuum dried at 180°C for 2 hours to synthesize SiO2. x Composite electrode (SiO) x / PAA).

[0099] The infrared spectra of the polymer binders (PTBR, PT, PBR, and TBR) in Example 1 and Comparative Examples 1-3 were detected, and the results are as follows: Figure 2 As shown in (a), PT is at 1717 cm. -1 The absorption peak is similar to that in PBR at 1720 cm⁻¹ -1 and PTBR 1711cm -1 The absorption peak can be attributed to the stretching vibration of C=O in the carboxyl group. As can be seen from the figure, after the introduction of TA, the PBR absorbs a peak at 1720 cm⁻¹. -1 The C=O absorption peak extends to 1711 cm⁻¹. -1 This indicates that hydrogen bonds formed between the -OH group of TA and the -COOH group of PBR, causing the absorption peak to shift to lower wavenumbers. To further reveal the types of hydrogen bonds present in PTBR, variable-temperature infrared spectroscopy was used to observe the changes in the FT-IR spectrum of PTBR as the temperature increased from 30℃ to 150℃. Figure 2 As can be seen in (b), the C=O deformation vibration region at room temperature can be divided into 1595, 1647 and 1735 cm⁻¹ by infrared peak fitting. -1 Three peaks, at 1647 and 1735 cm -1 The characteristic C=O peak at 1647 cm⁻¹ corresponds to the hydrogen bond formed between C=O in PAA / XNBR and the catechol group in TA (C=O··HO-Ph,I). Additionally, the peaks at 1647 and 1735 cm⁻¹... -1 The characteristic C=O peak at this location gradually shifts to higher wavenumbers with increasing temperature, indicating that C=O··HO-Ph gradually breaks down. At 150℃, the peaks are located at 1653 and 1743 cm⁻¹. -1The characteristic peaks can be attributed to the intramolecular hydrogen bonds (C=O···H-OOC, II) and the free C=O exposed by the breakage of C=O··HO-Ph in PAA / XNBR. Therefore, the polymer binder PTBR has physical crosslinking with multiple hydrogen bonds, mainly C=O··HO-Ph at room temperature. As the temperature increases, this type of hydrogen bond breaks, gradually changing to a combination of intramolecular hydrogen bonds (C=O···H-OOC) and free C=O.

[0100] The photoelectron spectroscopy of single physical / chemical double crosslinked conductive polymer networks (XNBR-SCNT-NH2, TA-SCNT-NH2, and PAA-SCNT-NH2) in Comparative Examples 4-6 was used to determine the interaction between the conductive agent and the binder. The results are as follows: Figure 2 As shown in (c), the crosslinked networks of XNBR-SCNT-NH2 and PAA-SCNT-NH2 both exhibit a characteristic O=CN peak at ~401.8 eV, indicating that an amidation reaction occurs between the -COOH groups of PAA / XNBR and the -NH2 groups of SCNT-NH2 at 150 °C. However, due to the incompleteness of this reaction, a hydrogen bond (C=O···H-NH-Ph) also exists in the complex. Furthermore, after SCNT-NH2 is mixed with TA, the only CN peak in SCNT-NH2 shifts towards a higher binding energy, indicating the existence of a hydrogen bond (Ph-OH···H-NH-Ph) between the two. In summary, the PTBR-SCNT-NH2 in Examples 4-5 exhibits both chemical and physical crosslinking, representing a novel physical-chemical dual-crosslinked three-dimensional conductive polymer network.

[0101] The mechanical properties of the polymer binders (PTBR and PT) in Example 1 and Comparative Example 2 were tested as follows: Figure 3 As shown. Figure 3 Figure (a) shows the tensile stress-strain curves of the polymer binders (PTBR and PT) in Example 1 and Comparative Example 2. It can be seen that the stress-strain curve of the PTBR sample is a non-Hooke type curve, with a Young's modulus of 5.7 MPa and a strain exceeding 560% before fracture, indicating that PTBR has high strength and good toughness. Furthermore, its high strain can fully withstand the nearly 400% volume change of the silicon anode during cycling. Conversely, the PT sample exhibits a Hooke type stress-strain curve, with a strain of only 8.2% at fracture and a large Young's modulus (17 MPa), indicating that PT is highly brittle. In addition, this invention conducted cyclic tensile tests on the PTBR sample alone, further exploring its energy dissipation capability through changes in the sample hysteresis curve. Figure 3Figure (b) shows the stress-strain curves of the PTBR cyclic tensile test in Example 1. It can be seen that the PTBR retains 65% of its strain after the first loading-unloading cycle. After resting for 15 minutes, subsequent loading-unloading cycle tests were conducted. It can be seen that the sample exhibits obvious hysteresis, indicating that its energy dissipation capacity is slightly reduced. Its residual strain is as high as 93.8% compared to the strain after the first cycle, indicating that it has good recovery capacity and energy dissipation capacity in subsequent cycles.

[0102] The mechanical properties of the composite electrodes of Example 6 and Comparative Examples 1-3 were tested, and the results are as follows: Figure 4 As shown, where Figure 4 In Figures (a), (b), and (c), the load-displacement curves, modulus, hardness, and elastic recovery plots of the composite electrodes (μSi / PTBR, μSi / PBR, μSi / PT, and μSi / TBR), respectively, are shown. Figure 4 As shown in Figure (a), when the indentation depth is controlled at ~1000 nm, the μSi / PTBR electrode exhibits the highest load (2.337 mN), significantly higher than that of the μSi / PT (1.048 mN), μSi / TBR (1.213 mN), and μSi / PBR electrodes (0.822 mN), indicating that μSi / PTBR possesses the strongest stress resistance. Furthermore, Figure 4 In (b) and (c), the modulus and hardness of μSi / PTBR were 1.4507 GPa and 0.0765 GPa, respectively, both higher than other composite electrodes, further demonstrating that μSi / PTBR has the strongest deformation resistance. The indentation depth of μSi / PTBR after load removal recovered from 1011.01 nm to 566.91 nm, corresponding to an elastic recovery rate of 43.93%, while the elastic recovery rates of μSi / PT, μSi / TBR, and μSi / PBR electrodes were 27.56%, 34.97%, and 31.18%, respectively. μSi / PTBR exhibits the highest elastic recovery, which is related to... Figure 3 The higher strain results in (a) are consistent with the high strain results, which is beneficial for withstanding the huge stress generated during the cycling of the micron-sized silicon anode, thereby maintaining the integrity of the electrode.

[0103] The electrochemical performance of the composite electrode half-cells in Examples 6, 7, Comparative Examples 1-3, and Comparative Example 7 was tested, and the results are as follows: Figure 5 and 6 As shown, where, Figure 5 In Figures (a), (b), and (d), the first charge-discharge curves (0.6 A g) of the composite electrode μSi / PTBR in Example 6 and the composite electrodes (μSi / PBR, μSi / PT, and μSi / TBR) in Comparative Examples 1-3 are shown. -1 and 2A g -1 Cyclic performance graph at current density, from Figure 5 As can be seen in (a), μSi / PTBR at 100 mA g -1 It has a capacity of 3807.2 mAhg -1 It has an ultra-high reversible capacity, and is higher than μSi / PT (3197mAh g). -1 ), μSi / PBR (3474.9mAh g) -1 ) and μSi / TBR (3542.9mAh g) -1 ). Figure 5 (b) μSi / PTBR electrode at 0.6 A g -1 After 50 cycles, the discharge specific capacity decreased from 3449 mAh g. -1 Decayed to 3173.6 mAh g -1 This corresponds to a capacity retention of approximately 92%. In comparison, the μSi / PT electrode, under the same conditions, exhibited a capacity retention of 3105.1 mAh g⁻¹. -1 Decayed to 2756.2 mAh g -1 The capacity retention rate is ~88.76%; the discharge specific capacity of μSi / PBR is 2840.1 mAh g. -1 Decrease to 2336.5mAh g -1 The capacity retention rate is ~82.2%. When the test current is increased to 2.0 Ag... -1 At times, such as Figure 5 As shown in Figure (d), μSi / PTBR still exhibits the best electrochemical performance, with its discharge capacity increasing from 2027 mAh g⁻¹ after 19 cycles. -1 After 180 cycles, the mAh capacity only decreased to 1968 g. -1 (At the 200th cycle), it exhibits a capacity retention of up to 97%, while μSi / PT retains only 1220.3 mAh g⁻¹ after 160 cycles under the same conditions. -1 The capacity retention rate was only 59.67%. Furthermore, the μSi / PBR and μSi / TBR electrodes at 2.0 Ag... -1 It exhibits severe capacity decay and poor cycle performance. Figure 5 (c) shows the cycling performance of the composite electrode μSi / PTBR in Example 6 under different Si loadings. As can be seen from the figure, the Si loading is 0.675 mg / cm³. -2 At 0.6A g, μSi / PTBR -1 After 50 cycles, the surface area capacity remained at ~2.0 mAh / cm³. -2 It exhibits excellent cycle stability. The Si loading was increased to 1.103 mg cm⁻¹. -2 At that time, the initial areal capacity of the electrode was 3.265 mAh cm⁻¹. -2After 50 cycles, the capacity drops to 2.949 mAh / cm³. -2 Its capacity retention rate is approximately 90.3%; the Si loading is further increased to 1.438 mg / cm³. -2 Although the cycling stability of μSi / PTBR decreases, its areal capacity still remains at 3.6 mAh / cm² after 50 cycles. -2 . Figure 6 In the middle (a), the composite electrode SiOx / PTBR in Example 7 and the composite electrode SiO in Comparative Example 7 are shown. x The first charge-discharge curve of / PAA can be seen from the figure, SiO x / PTBR's initial discharge specific capacity can reach 2450.4 mAh g -1 The initial coulomb efficiency was 68.8%, significantly better than that of SiO. x Electrochemical performance of PAA. Figure 6 (b) is SiO x / PTBR and SiO x / PAA electrode long-cycle performance diagram. From the diagram, it can be seen that SiO x / PTBR at 1.5A g -1 After 1000 cycles, the capacity loss per cycle is approximately 0.012% (from the 25th cycle to the 1000th cycle); while SiO x The / PAA electrode exhibited a capacity retention of only 41.04% after 1000 cycles, with a capacity loss of approximately 0.059% per cycle. Its capacity decay rate was significantly higher than that of SiO₂. x 5 times that of / PTBR.

[0104] The electrochemical performance of the full cell (NCM811 / / μSi / PTBR) assembled with a commercial lithium-ion ternary cathode in Example 6 was tested, and the results are as follows: Figure 7 As shown, where Figure 7 Figures (a) and (b) show the charge-discharge curves and cycle performance of the full cell, respectively. As can be seen from the figures, NCM811 / / μSi / PTBR achieves a cycle performance of [missing data - likely a value] at 20 mAg [missing data - likely a value]. -1 and 40mA g -1 The following exhibit similar discharge specific capacity (197mAh g). -1 The battery has a capacity of 40mA g. -1 The capacity retention rate was 88.4% after 50 current density cycles, indicating good cycle stability of the full cell. In summary, the excellent capacity output and cycle stability of the NCM811 / / μSi / PTBR full cell demonstrate that this physical-chemical dual-crosslinked conductive polymer network is suitable for research on commercial high-performance lithium-ion batteries and has extremely high practical value.

[0105] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a physical-chemical double-crosslinked conductive polymeric network, characterized in that, Includes the following steps: A polymer binder was formulated into a polymer binder solution. The polymer binder solution was mixed evenly with aminated carbon nanotubes. Then, a physical-chemical double cross-linked three-dimensional conductive polymer network was synthesized by means of the amidation reaction between the polymer binder and the aminated carbon nanotubes. The preparation method of the polymer binder includes the following steps: A carboxyl-containing polymer and tannic acid are dissolved in N-methylpyrrolidone to obtain a clear, pale yellow solution; the mass ratio of the carboxyl-containing polymer to tannic acid is 2:1 to 5:1; the carboxyl-containing polymer is one or more of polyacrylic acid and sodium polyacrylate. A carboxyl-containing rubber is added to the clear, pale yellow solution and stirred to obtain a suspension. The stirring is performed by first stirring at a low temperature of 80-100 °C for 8-12 h, and then raising the temperature to 150-160 °C and continuing stirring for 2-3 h. The mass ratio of the carboxyl-containing polymer to the carboxyl-containing rubber is 2:1 to 5:

1. The carboxyl-containing rubber is one or more of carboxyl butadiene rubber, carboxyl styrene-butadiene rubber, and carboxyl acrylonitrile rubber. The suspension is filtered, evaporated, and dried. The evaporation is performed by rotary evaporation of the filtered liquid at 100-120 °C, and the drying is performed by vacuum drying at 100-120 °C until it is completely dry, to obtain a polymer binder.

2. The method for preparing the physical-chemical double-crosslinked conductive polymer network according to claim 1, characterized in that, The aminated carbon nanotubes are one type of aminated long single-walled carbon nanotubes and aminated long multi-walled carbon nanotubes.

3. The method for preparing the physical-chemical double-crosslinked conductive polymer network according to claim 1, characterized in that, The concentration of the polymer binder solution is 20-40 mg·mL. -1 .

4. The method for preparing the physical-chemical double-crosslinked conductive polymer network according to claim 1, characterized in that, The mass ratio of the aminated carbon nanotubes to the polymer binder is 1:1 to 1:

2.

5. The method for preparing the physical-chemical double-crosslinked conductive polymer network according to claim 1, characterized in that, The amidation reaction between the polymer binder and the aminated carbon nanotubes during the drying process involves vacuum drying at 120-180 °C for 2-3 h.

6. The physical-chemical double-crosslinked conductive polymer network prepared by the method according to any one of claims 1 to 5.

7. The physical-chemical double-crosslinked conductive polymer network of claim 6 in the preparation of micron-sized silicon and / or SiO x Applications in negative electrodes or lithium-ion batteries.

8. A lithium-ion battery micron-sized silicon and / or SiO comprising the physical-chemical dual-crosslinked conductive polymer network of claim 6 x The method for preparing the negative electrode is characterized in that, Includes the following steps: The polymer binder is formulated into a polymer binder solution, and a slurry coating process is used to coat micron-sized silicon or SiO2. x A polymer binder solution is mixed with aminated carbon nanotubes and coated onto copper foil. During the drying process, the polymer binder undergoes an amidation reaction with the aminated carbon nanotubes to synthesize a physically-chemically cross-linked conductive polymeric network of micron-sized silicon or SiO₂. x Composite electrodes, namely micron-sized silicon or SiO2 electrodes for lithium-ion batteries. x negative electrode; The preparation method of the polymer binder includes the following steps: A carboxyl-containing polymer and tannic acid are dissolved in N-methylpyrrolidone to obtain a clear, pale yellow solution; the mass ratio of the carboxyl-containing polymer to tannic acid is 2:1 to 5:1; the carboxyl-containing polymer is one or more of polyacrylic acid and sodium polyacrylate. A carboxyl-containing rubber is added to the clear, pale yellow solution and stirred to obtain a suspension. The stirring is performed by first stirring at a low temperature of 80-100 °C for 8-12 h, and then raising the temperature to 150-160 °C and continuing stirring for 2-3 h. The mass ratio of the carboxyl-containing polymer to the carboxyl-containing rubber is 2:1 to 5:

1. The carboxyl-containing rubber is one or more of carboxyl butadiene rubber, carboxyl styrene-butadiene rubber, and carboxyl acrylonitrile rubber. The suspension is filtered, evaporated, and dried. The evaporation is performed by rotary evaporation of the filtered liquid at 100-120 °C, and the drying is performed by vacuum drying at 100-120 °C until it is completely dry, to obtain a polymer binder.

9. The lithium-ion battery micron-sized silicon and / or SiO according to claim 8 x The method for preparing the negative electrode is characterized in that, The aminated carbon nanotubes are one type of aminated long single-walled carbon nanotubes and aminated long multi-walled carbon nanotubes.

10. The lithium-ion battery micron-sized silicon and / or SiO according to claim 8 x The method for preparing the negative electrode is characterized in that, The concentration of the polymer binder solution is 20-40 mg·mL. -1 .

11. The lithium-ion battery micron-sized silicon and / or SiO according to claim 8 x The method for preparing the negative electrode is characterized in that, The mass ratio of the aminated carbon nanotubes to the polymer binder is 1:1 to 1:2; the aminated carbon nanotubes are bonded to micron-sized silicon or SiO2. x The mass ratio is 1:7 to 1:

8.

12. The lithium-ion battery micron-sized silicon and / or SiO according to claim 8 x The method for preparing the negative electrode is characterized in that, The amidation reaction between the polymer binder and the aminated carbon nanotubes during the drying process involves vacuum drying at 120-180 °C for 2-3 h.

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