Conductive binder for silicon-based negative electrode of lithium ion battery as well as preparation method and application of conductive binder
By preparing a conductive binder crosslinked with silver nanowires, the conductivity and stability issues of silicon-based anode materials for lithium-ion batteries were solved, achieving high-capacity and long-cycle-life lithium-ion battery performance.
Patent Information
- Application Number
- CN202511833763.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-03-03
AI Technical Summary
Existing silicon-based anode materials for lithium-ion batteries suffer from poor electronic conductivity and ion diffusion coefficients due to their large volume changes, which affects charge transfer kinetics. The addition of traditional binders reduces battery energy density and results in poor cycle stability.
Quaternary ammonium salts were prepared by reacting 9-bromo-1-nonanol and 2-[2-(dimethylamino)ethoxy]ethanol, and then crosslinked with polyacrylic acid and silver nanowires to form a conductive binder. The high electrical conductivity and mechanical flexibility of the silver nanowires enhanced the interfacial bonding ability between the binder and SiOx particles.
This improved the conductivity and cycle stability of the silicon-based anode, enhanced the mechanical strength and electrochemical performance of the electrode, and achieved high-capacity and long-cycle-life lithium-ion battery performance.
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Figure CN121592280A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery technology, and more specifically relates to a conductive binder for silicon-based anodes of lithium-ion batteries, its preparation method, and its application. Background Technology
[0002] Lithium-ion batteries possess advantages such as high capacity, no memory effect, rapid reversible charge and discharge, and high coulombic efficiency. They are currently widely used in commercial products such as mobile phones, laptops, digital cameras, and new energy vehicles. In the application of anode materials for lithium-ion batteries, silicon is considered the most promising next-generation anode material, with a theoretical capacity as high as 4200 mAh / g, far exceeding the 372 mAh / g capacity of commercial graphite. However, due to the enormous volume change (approximately 300%) of silicon-based anode materials, the electronic conductivity and ion diffusion coefficient of silicon particles are approximately ~10⁻⁶. −3 S cm −1 and 10 −12 cm 2 S −1 Poor electronic conductivity and ion diffusion coefficient lead to slow charge transfer kinetics, which is detrimental to the full utilization of silicon active particles at high current densities.
[0003] As a crucial component of electrodes, binders play a vital role in maintaining electrode stability and enhancing the electrical contact between active materials and current collectors. Developing strong binders is an effective means of solving the problems of silicon anodes. However, traditional non-conductive binders and conductive additives are both inactive substances, and their excessive addition reduces battery energy density. Furthermore, when particulate conductive carbon is used as a conductive additive, the drastic volume change of the active material during cycling can easily lead to loss of contact, resulting in broken electronic connections and rapid capacity decay. Therefore, developing high-capacity composite binders for silicon anodes remains a pressing technical challenge. Summary of the Invention
[0004] The purpose of this invention is to provide a conductive binder for silicon-based anodes of lithium-ion batteries, its preparation method, and its application, so as to solve the problems existing in the prior art.
[0005] To achieve the above objectives, the present invention provides the following solution:
[0006] One of the technical solutions of this invention: provides a method for preparing a conductive binder for a silicon-based anode in lithium-ion batteries, comprising the following steps:
[0007] Using 9-bromo-1-nonanol and 2-[2-(dimethylamino)ethoxy]ethanol as reactants, a quaternary ammonium salt was obtained via a nucleophilic substitution reaction;
[0008] The conductive adhesive is obtained by cross-linking reaction using the quaternary ammonium salt, polyacrylic acid, and silver nanowires as reactants.
[0009] Furthermore, the molar ratio of 9-bromo-1-nonanol and 2-[2-(dimethylamino)ethoxy]ethanol is 1:1-1.2.
[0010] Furthermore, the nucleophilic substitution reaction is carried out at a temperature of 60-70°C for 12 hours.
[0011] Furthermore, the mass ratio of the quaternary ammonium salt to polyacrylic acid is 1:1-9.
[0012] Furthermore, the polyacrylic acid has a molecular weight of 240,000 to 3,000,000 and is added in the form of an aqueous solution at a concentration of 5 to 10 wt%.
[0013] Furthermore, the amount of silver nanowires used is 10-30 wt% of the sum of the mass of the quaternary ammonium salt and polyacrylic acid.
[0014] Furthermore, the cross-linking reaction takes 0.5-2 hours.
[0015] The second technical solution of the present invention provides a conductive binder for a silicon-based anode of a lithium-ion battery, wherein the conductive binder for the silicon-based anode of a lithium-ion battery is prepared by the above-described preparation method.
[0016] The third technical solution of the present invention provides an electrode modification material for lithium-ion batteries, wherein the electrode modification material includes the conductive binder used for silicon-based anodes of lithium-ion batteries.
[0017] Furthermore, the electrode modification material also includes active substances and conductive agents.
[0018] Optionally, the active material is SiO2. x , of which 0 <x<2。
[0019] Optionally, the conductive agent includes conductive carbon black, carbon nanotubes, highly conductive carbon black, or conductive graphite.
[0020] Optionally, the mass ratio of the active material, the conductive agent, and the conductive binder for the silicon-based anode of the lithium-ion battery is 7-8:1-2:1.
[0021] The fourth technical solution of the present invention provides an electrode for a lithium-ion battery, wherein the electrode for a lithium-ion battery is obtained by modifying the current collector with the above-mentioned electrode modification material for lithium-ion batteries.
[0022] Optionally, the current collector may include copper foil.
[0023] Optionally, the loading of the electrode modification material for lithium-ion batteries in the electrode is 0.9-1 mg / cm³. 2 .
[0024] The fifth technical solution of the present invention provides the application of the above-mentioned conductive binder for silicon-based negative electrodes of lithium-ion batteries, or the above-mentioned electrode modification material for lithium-ion batteries, or the above-mentioned electrode for lithium-ion batteries in the preparation of lithium-ion batteries.
[0025] The sixth technical solution of the present invention: a lithium-ion battery, wherein the negative electrode of the lithium-ion battery is the electrode used in the above-mentioned lithium-ion battery.
[0026] The present invention discloses the following technical effects:
[0027] The slurry (electrode modification material) prepared by the binder provided by this invention has advantages such as good dispersibility and strong conductivity, and can effectively improve the SiO₂ process during electrode charging and discharging. x The poor conductivity of the negative electrode material makes SiO₂... x The anode exhibits good cycle stability, significantly improving the electrochemical performance of silicon-based anodes in lithium-ion batteries.
[0028] This invention prepares a small-molecule quaternary ammonium salt through a nucleophilic substitution reaction of 9-bromo-1-nonanol and 2-[2-(dimethylamino)ethoxy]ethanol, and then crosslinks it with polyacrylic acid and silver nanowires to synthesize a conductive binder with excellent mechanical strength, enabling the cycling stability of silicon-based anodes. The polyacrylic acid used in this binder has a linear structure rich in carboxyl groups, resulting in good bonding performance. The conductive binder utilizes non-covalent interactions between molecules (hydrogen bonds, van der Waals forces, and ionic interactions, etc.) to achieve efficient adhesion. The addition of silver nanowires endows the electrode modification material with an excellent conductive network, facilitating electron and ion transport and significantly improving the conductivity of the electrode modification material, enabling the electrode to maintain stable electrochemical performance during cycling. Silver nanowires possess ultra-high conductivity and a high aspect ratio; their one-dimensional linear structure can "bridge" between silicon particles, forming a three-dimensional conductive network that runs through the electrode. Simultaneously, silver nanowires exhibit good mechanical flexibility and ductility, accommodating the significant volume expansion during the charging and discharging process of the silicon anode. Small molecule quaternary ammonium salts have quaternary ammonium salt cations, which can form hydrogen bonds or electrostatic interactions with hydroxyl groups and polyacrylic acid on the surface of silicon anodes, thereby strengthening the conductive network.
[0029] In the electrode modification material provided by this invention, the conductive binder and SiO x The particles have abundant binding sites, allowing the binder to bind with SiO₂. x The particles have strong interfacial bonding ability, SiO xThe negative electrode can better withstand volume changes during electrode charging and discharging. Therefore, based on its good adhesion and mechanical strength, SiO2 using this binder is preferred. x The negative electrode achieves stable long-cycle performance. Attached Figure Description
[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0031] Figure 1 Cycle performance of CR2032 coin cells prepared using the binder of Example 2.
[0032] Figure 2 Comparison of cycle performance of CR2032 coin cells prepared with binders from Examples 1-3.
[0033] Figure 3 Comparison of cycle performance of CR2032 coin cells prepared with binders from Example 2 and Comparative Examples 1-2. Detailed Implementation
[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0037] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0038] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0039] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products. The polyacrylic acid used in the specific embodiments of this invention has a molecular weight between 240,000 and 3,000,000, and the silver nanowires used have a diameter of 50 nm and a length of 100 µm.
[0040] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.
[0041] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0042] In some specific embodiments, the present invention provides a method for preparing a conductive binder for a silicon-based anode in a lithium-ion battery, comprising the following steps:
[0043] S1. Mix 9-bromo-1-nonanol and 2-[2-(dimethylamino)ethoxy]ethanol at a molar ratio of 1:1-1.2, add tetrahydrofuran, heat to 60-70℃, start magnetic stirring, react for 12h to obtain a yellow transparent liquid, cool at room temperature, then add diethyl ether to wash and remove impurities by rotary evaporation, cool to room temperature, collect the product to obtain quaternary ammonium salt;
[0044] S2. Mix the quaternary ammonium salt obtained in step S1 with polyacrylic acid at a mass ratio of 1:1-9, then add silver nanowires at a mass ratio of 10-30 wt% of the sum of the mass of the quaternary ammonium salt and polyacrylic acid, stir and react for 0.5-2 h to obtain a conductive binder for silicon-based anodes of lithium-ion batteries.
[0045] Polyacrylic acid is added in the form of an aqueous solution at a concentration of 5-10 wt%.
[0046] In some specific embodiments, the present invention provides a method for preparing a negative electrode for a lithium-ion battery, the steps of which include:
[0047] active material SiO xWhen \(0 < x < 2\), a conductive agent (electrical carbon black, carbon nanotubes, super conductive carbon black or conductive graphite) and the above conductive binder for the silicon-based anode of a lithium-ion battery are mixed in a mass ratio of 7 - 8:1 - 2:1 to obtain a mixed system. Then, an appropriate amount of deionized water is added to make the solid content of the system 40 - 50%. Subsequently, it is placed in a defoaming blender and stirred for 6 - 8 h to obtain a uniformly dispersed electrode modification material for a lithium-ion battery. The uniformly dispersed electrode modification material for a lithium-ion battery is coated on a copper foil and vacuum dried at 100 - 140 °C for 12 - 36 h to obtain a negative electrode for a lithium-ion battery with a loading of 0.9 - 1 mg / cm 2 of the lithium-ion battery.
[0048] The conductive binder provided by the present invention can combine the functions of adhesion and conductivity. When used for electrode preparation, on the one hand, the proportion of non-active components can be reduced, and the loading of active materials can be increased to improve the specific energy density of the battery; on the other hand, silver nanowires can serve as an electron transport bridge between particles, and as long as the active particles are in contact with the conductive binder, the electrochemical activity can be maintained, which is more conducive to the full utilization of capacity.
[0049] Example 1
[0050] The preparation steps of the conductive binder for the silicon-based anode of a lithium-ion battery include:
[0051] S1. Add 5 g of 9-bromo-1-nonanol and 3.15 g of 2-[2-(dimethylamino)ethoxy]ethanol into a flask, then add 60 mL of tetrahydrofuran. After heating to 70 °C, start magnetic stirring and react for 12 h to obtain a yellow transparent liquid. Cool it at room temperature, then add ether for washing and rotary evaporation to remove impurities. Then pour the liquid mixture into a glass dish and cool it to room temperature to obtain a quaternary ammonium salt;
[0052] S2. Mix the quaternary ammonium salt obtained in step S1 with polyacrylic acid (with a molecular weight of 450,000) in a mass ratio of 1:7. Then add 10 wt% of silver nanowires based on the sum of the masses of the quaternary ammonium salt and polyacrylic acid, and stir and react for 1 h to obtain a conductive binder for the silicon-based anode of a lithium-ion battery;
[0053] Polyacrylic acid is added in the form of an aqueous solution with a concentration of 5 wt%.
[0054] Example 2
[0055] The preparation steps of the conductive binder for the silicon-based anode of a lithium-ion battery include:
[0056] S1. Add 5g of 9-bromo-1-nonanol and 3.15g of 2-[2-(dimethylamino)ethoxy]ethanol to a flask, then add 60mL of tetrahydrofuran. Heat to 70℃ and start magnetic stirring. React for 12h to obtain a yellow transparent liquid. Cool at room temperature, then add diethyl ether to wash and remove impurities by rotary evaporation. Then pour the liquid mixture into a glass dish and cool to room temperature to obtain a quaternary ammonium salt.
[0057] S2. The quaternary ammonium salt obtained in step S1 is mixed with polyacrylic acid (molecular weight of 450,000) at a mass ratio of 1:7. Then, 20 wt% of silver nanowires (the sum of the mass of the quaternary ammonium salt and polyacrylic acid) are added and the mixture is stirred for 1 hour to obtain a conductive binder for silicon-based anodes of lithium-ion batteries.
[0058] Polyacrylic acid was added in the form of an aqueous solution at a concentration of 5 wt%.
[0059] Example 3
[0060] The preparation steps of the conductive binder for silicon-based anodes in lithium-ion batteries include:
[0061] S1. Add 5g of 9-bromo-1-nonanol and 3.15g of 2-[2-(dimethylamino)ethoxy]ethanol to a flask, then add 60mL of tetrahydrofuran. Heat to 70℃ and start magnetic stirring. React for 12h to obtain a yellow transparent liquid. Cool at room temperature, then add diethyl ether to wash and remove impurities by rotary evaporation. Then pour the liquid mixture into a glass dish and cool to room temperature to obtain a quaternary ammonium salt.
[0062] S2. The quaternary ammonium salt obtained in step S1 is mixed with polyacrylic acid (molecular weight of 450,000) at a mass ratio of 1:7. Then, 30 wt% of silver nanowires (the sum of the mass of the quaternary ammonium salt and polyacrylic acid) are added and the mixture is stirred for 1 hour to obtain a conductive binder for silicon-based anodes of lithium-ion batteries.
[0063] Polyacrylic acid was added in the form of an aqueous solution at a concentration of 5 wt%.
[0064] Comparative Example 1
[0065] The preparation steps of the adhesive include:
[0066] Adding 0.5 g of polyacrylic acid powder with a molecular weight of 450,000 to 9.5 g of deionized water yields a 5% (w / w) binder.
[0067] Comparative Example 2
[0068] The preparation steps of the adhesive include:
[0069] S1. Add 5 g of 9-bromo-1-nonanol and 3.15 g of 2-[2-(dimethylamino)ethoxy]ethanol into a flask, then add 60 mL of tetrahydrofuran. After heating to 70 °C, start magnetic stirring and react for 12 h to obtain a yellow transparent liquid. Cool it at room temperature, then add ether for washing and rotary evaporation to remove impurities. Then pour the liquid mixture into a glass dish and cool it to room temperature to obtain the quaternary ammonium salt;
[0070] S2. Mix the quaternary ammonium salt obtained in step S1 and polyacrylic acid (with a molecular weight of 450,000) in a mass ratio of 1:7, and stir and react for 1 h to obtain the binder;
[0071] Polyacrylic acid is added in the form of an aqueous solution with a concentration of 5 wt%.
[0072] Test Example
[0073] Preparation of the negative electrode:
[0074] Mix the active substance SiO x (0 < x < 2), the conductive agent (superconductive carbon black Super P), and the binder (Examples 1-2 and Comparative Example 1) in a mass ratio of 7:2:1 to obtain a mixed system. Add an appropriate amount of deionized water to make the solid content of the system between 40% and 50%. Then put it into a defoaming mixer and stir for 6 h to obtain a uniformly dispersed electrode modification material for lithium-ion batteries. Coat the uniformly dispersed electrode modification material for lithium-ion batteries onto a copper foil, dry it in vacuum at 140 °C for 12 h, and cut it into circular negative electrode sheets with a diameter of 12 mm to obtain a negative electrode for lithium-ion batteries with a loading of 1 mg / cm 2 of lithium-ion batteries.
[0075] Preparation of CR2032 coin cells:
[0076] Transfer the above negative electrode into a glove box filled with argon. Use a lithium sheet as the counter electrode. The electrolyte uses LiPF6 with a solute of 1.0 mmol / L and solvents of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1. Among them, 10 wt% fluoroethylene carbonate (FEC) and 1 wt% vinylene carbonate (VC) are used as additives. Assemble using CR2032 coin cells, and let the assembled coin cells stand at 28 °C for 10 h. Test the electrochemical performance of the standing cells in a Neware test system under constant current.
[0077] The test conditions are: current density 500 mA / g; voltage window 0.01 - 1.5 V.
[0078] The batteries prepared with the binders in Examples 1-3 are denoted as SiO x @PQA; the batteries prepared with the binder in Comparative Example 1 are denoted as SiOx @PAA; The battery prepared with the binder in Comparative Example 2 is denoted as SiO. x @PQ.
[0079] Figure 1 Cycle performance of CR2032 coin cells prepared using the binder of Example 2. As can be seen from the figure, the SiO2 cells prepared using the conductive binder of Example 2 exhibit... x At a current density of 1000 mA / g, the electrode exhibits an initial discharge specific capacity of over 2000 mAh / g and an initial coulombic efficiency of over 60%. After 600 cycles, the capacity remains at 964.45 mAh / g, with a capacity retention of 88.07%, demonstrating excellent cycle stability.
[0080] Figure 2 The graph shows a comparison of the cycle performance of CR2032 coin cells prepared with the binders in Examples 1-3. As can be seen from the graph, the coin cell prepared in Example 1 exhibits a capacity decay of 1034.88 mAh / g after 150 cycles at a current density of 500 mA / g, while the coin cell prepared in Example 3 exhibits a capacity decay of 986.8 mAh / g after 150 cycles at the same current density. The coin cell prepared in Example 2 maintains a capacity of 1174 mAh / g, demonstrating higher discharge capacity and better cycle stability. This indicates that using a conductive binder with a silver nanowire content of 20% can effectively bind SiO2. x The negative electrode exhibits good cycle stability.
[0081] Figure 3 The graph shows a comparison of the cycle performance of CR2032 coin cells prepared using the binders of Examples 2 and Comparative Examples 1-2. As can be seen from the graph, the coin cell prepared in Comparative Example 1 exhibits a capacity decay of 927 mAh / g after 150 cycles at a current density of 500 mA / g, while the coin cell prepared in Comparative Example 2 exhibits a capacity decay of 1031 mAh / g after 150 cycles at the same current density. The coin cell prepared in Example 2 maintains a capacity of 1173 mAh / g, demonstrating higher discharge capacity and better cycle stability. This indicates that the conductive binder used in this application can effectively bind SiO2. x The negative electrode exhibits good cycle stability.
[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0083] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a conductive binder for a silicon-based anode in a lithium-ion battery, characterized in that the steps include... include: Using 9-bromo-1-nonanol and 2-[2-(dimethylamino)ethoxy]ethanol as reactants, a quaternary ammonium salt was obtained via a nucleophilic substitution reaction; The conductive adhesive is obtained by cross-linking reaction using the quaternary ammonium salt, polyacrylic acid, and silver nanowires as reactants.
2. The preparation method according to claim 1, characterized in that, The molar ratio of 9-bromo-1-nonanol to 2-[2-(dimethylamino)ethoxy]ethanol is 1:1-1.2; And / or, the mass ratio of the quaternary ammonium salt to polyacrylic acid is 1:1-9; And / or, the polyacrylic acid has a molecular weight of 240,000 to 3,000,000 and is added in the form of an aqueous solution at a concentration of 5-10 wt%. And / or, the amount of silver nanowires used is 10-30 wt% of the sum of the mass of the quaternary ammonium salt and polyacrylic acid.
3. The preparation method according to claim 1, characterized in that, The nucleophilic substitution reaction was carried out at a temperature of 60-70℃ for 12 hours. And / or, the crosslinking reaction takes 0.5-2 hours.
4. A conductive binder for silicon-based anodes in lithium-ion batteries, characterized in that, The conductive binder for the silicon-based anode of lithium-ion batteries is prepared by the preparation method according to any one of claims 1-3.
5. An electrode modification material for lithium-ion batteries, characterized in that, The electrode modification material includes the conductive binder for silicon-based anodes of lithium-ion batteries as described in claim 4.
6. The electrode modification material as described in claim 5, characterized in that, The electrode modification material also includes active substances and conductive agents.
7. The electrode modification material as described in claim 6, characterized in that, The active material is SiO₂. x , of which 0 <x<2; And / or, the conductive agent includes conductive carbon black, carbon nanotubes, highly conductive carbon black, or conductive graphite; And / or, the mass ratio of the active material, the conductive agent, and the conductive binder for the silicon-based negative electrode of the lithium-ion battery is 7-8:1-2:
1.
8. An electrode for a lithium-ion battery, characterized in that, The electrode for the lithium-ion battery is obtained by modifying the current collector with the electrode modification material for the lithium-ion battery as described in any one of claims 5-7.
9. The application of the conductive binder for a silicon-based negative electrode of a lithium-ion battery as described in claim 4, or the electrode modification material for a lithium-ion battery as described in any one of claims 5-7, or the electrode for a lithium-ion battery as described in claim 8, in the preparation of a lithium-ion battery.
10. A lithium-ion battery, characterized in that, The negative electrode of the lithium-ion battery is the electrode for a lithium-ion battery as described in claim 8.