A polysaccharide-based adhesive, its preparation method and application
By grafting polysaccharide segments and polyacrylic acid segments onto the polysaccharide backbone, the problems of volume change and interfacial reaction regulation in zinc-based batteries were solved, improving the stability and safety of the batteries and achieving efficient ion transport and mechanical strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN UNIV
- Filing Date
- 2026-03-18
- Publication Date
- 2026-06-09
Smart Images
Figure CN122168206A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of zinc-ion battery materials technology, and in particular to a polysaccharide-based binder, its preparation method and application. Background Technology
[0002] Currently, aqueous zinc-ion batteries have attracted widespread attention due to their high safety, low cost, and environmental friendliness. The zinc-based battery electrode has a specific capacity of 820 mAh / g and a specific capacity of 5855 mAh / cm³. 3 Compared to the standard hydrogen electrode, the redox potential is -0.762V. Based on this, zinc-based battery electrodes, when paired with high-voltage cathode materials, can provide battery-level energy densities ranging from 70Wh / kg to 140Wh / kg. Therefore, although zinc-based anode materials have a lower energy density compared to lithium-ion batteries, they are still considered a potential alternative for large-scale energy storage applications. Current industry research on aqueous zinc-ion batteries focuses on developing electrodes with a thickness of 10μm or less, equivalent to a capacity of 5.9mAh / cm². 2 While zinc foil, with its large area capacity, is used in batteries, the production of ultra-thin zinc foil is technically challenging and costly. In contrast, zinc-based battery electrodes made from zinc powder are easier to adjust in terms of area capacity, are more compatible with current battery production lines, have the potential for large-scale processing, and are inexpensive, attracting increasing attention from researchers.
[0003] However, zinc powder electrodes with high specific surface areas undergo significant volume changes during long-term cyclic use. Binders, as a crucial component of battery electrodes, enable zinc-based battery electrodes to exhibit superior electrochemical performance. Therefore, binders not only need broad adhesion to various electrode components but also require high mechanical strength and a certain degree of viscoelasticity to enhance the stability of the electrode structure, thereby adapting to volume changes during repeated deposition / stripping processes. Currently, binders widely used in the industry are mainly divided into two categories: organic binders represented by polyvinylidene fluoride (PVDF) and aqueous binders represented by carboxymethyl cellulose (CMC). However, these two traditional binders are mostly electrochemically inert materials, making it difficult to adapt to the volume changes and interfacial reaction control requirements of zinc-based battery electrodes in aqueous environments.
[0004] At this time, polysaccharide-based materials, due to their rich content of polar functional groups such as hydroxyl groups in their molecular chains, possess excellent film-forming properties, adhesion properties, and interfacial compatibility with metal surfaces, thus attracting widespread attention and being widely used in electrode binder systems. Furthermore, polysaccharides are widely available and environmentally friendly, exhibiting good chemical stability in aqueous electrolyte environments, which is beneficial for maintaining the long-term stability of the electrode structure. However, traditional polysaccharide binders still have certain limitations in ion transport regulation and electrochemical interfacial stability, making it difficult to simultaneously achieve both mechanical strength and electrochemical performance under high current density or long cycling conditions. Therefore, there is an urgent need to develop a binder that can simultaneously improve the electrochemical performance and mechanical strength of zinc-based battery electrodes, thereby developing battery electrodes with good structural stability and long-term service stability. Summary of the Invention
[0005] One objective of this application is to provide a polysaccharide-based binder, its preparation method and application. By using the polysaccharide-based binder and electrode slurry provided in this application, it is beneficial to improve the stability and service life of battery electrodes, and further enhance the stability and safety during long-term cyclic use.
[0006] One objective of this application is to provide a polysaccharide-based binder, its preparation method, and its application, which helps to regulate zinc deposition behavior, suppress dendrite growth and hydrogen evolution reaction while ensuring the structural integrity of battery electrodes, thereby improving the cycle stability and safety of zinc-ion batteries.
[0007] To achieve the above objectives, this application provides a polysaccharide-based binder comprising: (a) a polysaccharide backbone; and (b) grafted side chains, wherein the grafted side chains are grafted onto the polysaccharide backbone, and the grafted side chains include a first grafted side chain and a second grafted side chain, wherein the first grafted side chain includes a polyionic liquid segment and the second grafted side chain includes a polyacrylic acid segment.
[0008] In some embodiments, the polysaccharide-based binder satisfies at least one of the following conditions: (a) the polyionic liquid segment comprises an aromatic group and a conductive polymeric group, wherein the aromatic group comprises at least one of phenyl, styryl, benzyl or a derivative thereof, and the conductive polymeric group comprises at least one of imidazolium, pyridinium, pyrrolidineium or quaternary ammonium cations; (b) the content ratio of the polyionic liquid segment to the polyacrylic acid segment is in the range of (3~5):1; (c) the polysaccharide backbone is at least one of chitin backbone, cellulose backbone, and starch backbone.
[0009] To achieve the above objectives, this application also provides a method for preparing a polysaccharide-based binder, the method comprising the following steps: S100, dissolving polysaccharide in an ionic liquid and reacting it with an acyl bromide compound to obtain a bromine-containing initiator; S200, reacting the bromine-containing initiator, carbon disulfide, and a thiol compound under an alkaline environment to obtain a chain transfer agent; S300, quaternizing an N-substituted imidazole with a monomer including an aromatic group or its derivative group to obtain an ionic liquid monomer including an aromatic group; S400, mixing the chain transfer agent, the ionic liquid monomer, an acrylic monomer, and a free radical polymerization initiator in the liquid phase to carry out a reversible addition-fragmentation chain transfer polymerization reaction to obtain an intermediate product; S500, subjecting the intermediate product to an anion exchange reaction with a bis(trifluoromethanesulfonyl)imide salt, collecting the precipitate, washing and drying it to obtain the polysaccharide-based binder.
[0010] To achieve the above objectives, this application also provides the application of the aforementioned polysaccharide-based binder or the polysaccharide-based binder prepared by the aforementioned preparation method as a zinc-based negative electrode binder for zinc-ion batteries.
[0011] To achieve the above objectives, this application also provides an electrode paste, which includes the aforementioned polysaccharide-based binder and organic solvent, and further includes at least one of zinc powder and a conductive agent.
[0012] In some embodiments, the electrode paste satisfies at least one of the following conditions: (a) the conductive agent is at least one of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black; (b) the organic solvent is at least one of N-methylpyrrolidone, acetone, dimethyl sulfoxide, and N,N-dimethylformamide; and (c) the mass ratio of the zinc powder, the conductive agent, and the polysaccharide-based binder is (6~9):(0.5~2):(0.5~2).
[0013] In some embodiments, the electrode slurry includes the polysaccharide-based binder, the organic solvent, the zinc powder, and the conductive agent. The solid content of the electrode slurry is ≤60%. The conductive agent is at least two of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black. When the conductive agent is two of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black, the conductive agent includes a first conductive agent and a second conductive agent. The first conductive agent and the second conductive agent are different, and the mass ratio of the first conductive agent to the second conductive agent is 1:(0.5~2).
[0014] To achieve the above objectives, this application provides a battery electrode sheet, comprising the dried electrode slurry as described above.
[0015] In some embodiments, the battery electrode sheet is prepared by any of the following methods: (a) providing a current collector, coating the electrode paste onto the current collector, and drying the electrode paste to obtain the battery electrode sheet, wherein the current collector is aluminum foil, the drying temperature is 50°C to 100°C, and the drying time is 5h to 15h; (b) providing a substrate, printing the electrode paste onto the substrate, and drying the electrode paste to obtain a screen-printed flexible battery electrode sheet, wherein the drying process... The temperature is 50℃~100℃; the drying time is 5h~15h; the substrate is at least one of leaves, thin wood chips, and polyimide film; (c) after the electrode slurry is sprayed onto the polymer substrate, the electrode slurry is dried to obtain a sprayed zinc-based battery electrode sheet, the drying temperature is 50℃~100℃; the drying time is 5h~15h; the polymer substrate is at least one of polyvinyl chloride film, polyethylene terephthalate film, and polyimide film.
[0016] To achieve the above objectives, this application provides a battery comprising at least one battery electrode as described above.
[0017] Compared with the prior art, the beneficial effects of this application are as follows: (1) By grafting polyionic liquid segments and polyacrylic acid segments onto the polysaccharide backbone, it is beneficial to improve the stability and service life, and further enhance the stability and safety during long-term cyclic use. On this basis, when the polysaccharide-based binder provided in this application is applied to the battery electrode, the structural integrity of the battery electrode is improved, and the zinc deposition behavior is regulated, inhibiting dendrite growth and hydrogen evolution reaction, thereby improving the cycle stability and safety of the application in zinc-ion batteries. It is worth mentioning that, since the polyionic liquid segments have high ionic conductivity and wide electrochemical window, grafting them onto the polysaccharide backbone is equivalent to introducing an ionic conductivity pathway into the polysaccharide-based binder, thereby promoting the rapid migration of ions inside the electrode and reducing electrode polarization. On the one hand, the polyacrylic acid segments containing a large number of carboxyl groups have good mechanical flexibility and adhesion ability, while improving the polymerization reaction efficiency and giving the material a certain degree of hydrophilicity. This hydrophilicity allows the polysaccharide-based binder to undergo limited swelling in an aqueous electrolyte environment, thereby providing a channel for the transport of working ions and alleviating the hindering effect of traditional binders on zinc ion transport.
[0018] (2) Polysaccharide-based materials are rich in polar functional groups such as hydroxyl groups on their molecular chains, exhibiting good film-forming properties, adhesion properties, and interfacial compatibility with metal surfaces. Therefore, they have received widespread attention and are widely used in electrode binder systems. Furthermore, polysaccharides are widely available and environmentally friendly, exhibiting good chemical stability in aqueous electrolyte environments, which is beneficial for maintaining the long-term stability of the electrode structure. Based on this, this application uses polysaccharide-based polymers as raw materials for grafting, which is beneficial for improving the stability of use when polysaccharide-based binders are used as binders for zinc-based battery electrodes. This further enhances the stability and lifespan of the battery when polysaccharide-based binders are applied in batteries. Attached Figure Description
[0019] Figure 1 This is a photograph of the zinc-based battery electrode prepared in Example 1 of this application.
[0020] Figure 2 The polysaccharide-based adhesive prepared in Example 1 of this application was divided into four pieces, two of which were stained dark with Coomassie Brilliant Blue, and then stretched after self-healing for 12 hours at room temperature.
[0021] Figure 3 The tensile stress-strain curves of the film prepared by the polysaccharide-based binder in Example 2 of this application before and after self-healing are shown.
[0022] Figure 4 This is a scanning electron microscope image of the cross-section of the zinc-based battery electrode prepared in Example 1 of this application.
[0023] Figure 5 The images show scanning electron microscope (SEM) images of the zinc powder electrode surfaces of a Zn||Zn symmetric battery assembled using the zinc-based battery electrode sheet (left) prepared in Example 1 of this application and the zinc-based battery electrode sheet (right) prepared in Comparative Example 1 as negative electrodes, disassembled after cycling.
[0024] Figure 6 The peel adhesion test curves at 180° are for the zinc-based battery electrodes prepared in Example 1 and Comparative Example 1 of this application.
[0025] Figure 7 The graphs show the cycle life test results of Zn||Zn symmetric batteries assembled as negative electrodes in Embodiment 1, Comparative Example 1, and Comparative Example 2 of this application.
[0026] Figure 8 This is a comparison chart of the coulombic efficiency and cycle life of Zn||Cu asymmetric batteries assembled as negative electrodes in Example 1, Comparative Example 1, and Comparative Example 2 of this application.
[0027] Figure 9The graphs show the discharge specific capacity and capacity retention of the Zn||V2O5 full cells assembled as negative electrodes in Example 1 and Comparative Example 1 of this application.
[0028] Figure 10 The graphs show the specific capacity and capacity retention of Zn||V2O5 full cells assembled as negative electrodes in Example 1 and Comparative Example 1 of this application at different current densities under different discharge rates.
[0029] Figure 11 This is a physical image of a Zn||V2O5 pouch cell assembled using Example 1 of this application as the negative electrode.
[0030] Figure 12 These are photographs showing the Zn||V2O5 pouch cell assembled as the negative electrode in Example 1 of this application, providing stable power supply under various harsh operating conditions.
[0031] Figure 13 The infrared spectra of the polysaccharide-based binder provided in Example 1 of this application and the elastomer materials provided in Comparative Examples 5-8 are shown.
[0032] Figure 14 The tensile stress-strain curves are those of the film prepared by the polysaccharide-based binder provided in Example 2 of this application and the elastomer materials provided in Comparative Examples 5 to 8.
[0033] Figure 15 Tensile stress-strain curves of the film prepared with the polysaccharide-based binder provided in Example 2 of this application and the polysaccharide-based binder film after swelling provided in Example 3.
[0034] Figure 16 Bar charts showing the tensile strength, toughness, and Young's modulus of the film prepared with the polysaccharide-based binder provided in Example 2 of this application and the swollen polysaccharide-based binder film provided in Example 3.
[0035] Figure 17 The ionic conductivity test curves (left) and the corresponding calculated ionic conductivity bar charts (right) of the film prepared with the polysaccharide-based binder provided in Example 2 of this application and the swollen polysaccharide-based binder film provided in Example 3.
[0036] Figure 18 This is a comparison of the cycle life of Zn||Zn symmetric cells assembled as negative electrodes in Comparative Example 3 and Comparative Example 9 of this application.
[0037] Figure 19 The infrared spectra of the cellulose-based binder provided in Example 4 and the starch-based binder provided in Example 5 of this application are shown.
[0038] Figure 20These are photographs showing the general adhesion of the polysaccharide-based binder provided in Example 1 of this application to various types of electrode assemblies. The test objects, from left to right, are polytetrafluoroethylene, aluminum foil, zinc foil, graphite, and alumina.
[0039] Figure 21 These are photographs showing the ultrasonic stability test results of the zinc-based battery electrodes prepared in Example 1 and Comparative Example 1 of this application in the electrolyte.
[0040] Figure 22 These are photographs of the screen-printed flexible electrodes obtained in Examples 6-8 of this application. From left to right, the substrates are fresh leaves, thin wood chips, and polyimide films, respectively.
[0041] Figure 23 This is a photograph of the zinc-based battery electrode sheet prepared in Example 9 of this application, with a polyvinyl chloride film as the substrate.
[0042] Figure 24 The chemical structural formula of the polysaccharide-based binder prepared in Example 1 of this application is shown.
[0043] Figure 25 Photographs of zinc-based battery electrodes with different areal capacities prepared using polysaccharide-based binders in Example 1 of this application.
[0044] Figure 26 Cycle life diagram of Zn||Zn symmetrical battery assembled using the battery electrodes provided in Embodiments 4 and 5 of this application as negative electrodes. Detailed Implementation
[0045] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0046] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variation thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements and may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.
[0047] When a quantity, concentration, or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range is disclosed as “1 to 5”, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range includes its endpoints and all integers and fractions within that range.
[0048] The approximate terms used in the specification and claims to modify quantities indicate that the application is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. Correspondingly, the use of "about," "approximately," etc., to modify a numerical value means that the application is not limited to that precise value. In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In the specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.
[0049] This application provides a polysaccharide-based binder comprising: (a) a polysaccharide backbone; and (b) grafted side chains, the grafted side chains being grafted onto the polysaccharide backbone, the grafted side chains comprising a first grafted side chain and a second grafted side chain, the first grafted side chain comprising a polyionic liquid segment, and the second grafted side chain comprising a polyacrylic acid segment.
[0050] By grafting polyionic liquid segments and polyacrylic acid segments onto the polysaccharide backbone, it is beneficial to improve the stability and service life, and further enhance the stability and safety during long-term cycling. Based on this, when the polysaccharide-based binder provided in this application is applied to battery electrodes, it improves the structural integrity of the battery electrodes, regulates zinc deposition behavior, and inhibits dendrite growth and hydrogen evolution reaction, thereby improving the cycle stability and safety in zinc-ion batteries. It is worth mentioning that, due to the high ionic conductivity and wide electrochemical window of the polyionic liquid segments, grafting them onto the polysaccharide backbone is equivalent to introducing an ion-conducting pathway into the polysaccharide-based binder, thereby promoting rapid ion migration within the electrode and reducing electrode polarization. On the one hand, the polyacrylic acid segments containing a large number of carboxyl groups have good mechanical flexibility and adhesion ability, while improving polymerization efficiency and imparting a certain degree of hydrophilicity to the material. This hydrophilicity allows the polysaccharide-based binder to undergo limited swelling in an aqueous electrolyte environment, thereby providing a channel for the transport of working ions and alleviating the hindering effect of traditional binders on zinc ion transport. It is understandable that when polysaccharide-based binders swell, they can simultaneously improve their mechanical strength and ionic conductivity, which is beneficial for constructing battery electrodes with high ionic conductivity and high operational stability, thereby improving the electrochemical performance of the electrodes.
[0051] Because polysaccharide-based materials are rich in polar functional groups such as hydroxyl groups on their molecular chains, they possess excellent film-forming properties, adhesion properties, and interfacial compatibility with metal surfaces, thus attracting widespread attention and being widely used in electrode binder systems. Furthermore, polysaccharides are widely available and environmentally friendly, exhibiting good chemical stability in aqueous electrolyte environments, which is beneficial for maintaining the long-term stability of the electrode structure. Based on this, this application uses polysaccharide-based polymers as raw materials for grafting, which helps improve the stability of polysaccharide-based binders when used as binders for zinc-based battery electrodes, thereby further enhancing the stability and lifespan of the battery electrodes when applied in their application. On the one hand, polysaccharides are extremely abundant in nature, aligning with the overall requirements of sustainable development and green manufacturing. On the other hand, polysaccharide-based binders possess good flexibility and viscoelasticity, effectively mitigating volume changes in zinc-based battery electrodes during cycling and preventing electrode pulverization and detachment.
[0052] Furthermore, the polysaccharide backbone forms a brush-like structure through grafting, and the polar groups in the brush-like structure can coordinate with zinc ions, uniformly regulating zinc deposition and inhibiting the growth of zinc dendrites. On the one hand, the brush-like polysaccharide-based adhesive has a three-dimensional spatial topology, allowing for relative slippage and orientation between the backbone and side chains, which is beneficial for improving the flexibility and elasticity of the adhesive. On the other hand, after penetrating into the interparticle gaps and curing, the brush-like polysaccharide-based adhesive not only increases the bonding area and forms a three-dimensional network, but also increases the interfacial bonding force between the polysaccharide-based adhesive and the material to be bonded, reducing the risk of debonding.
[0053] In some embodiments, the polysaccharide backbone is at least one of chitin backbone, cellulose backbone, and starch backbone. Because the molecular chains of polysaccharide-based materials are rich in polar functional groups such as hydroxyl groups, they exhibit excellent film-forming properties, adhesion properties, and interfacial compatibility with metal surfaces, thus attracting widespread attention and being applied in electrode binder systems. Furthermore, polysaccharides are widely available and environmentally friendly, exhibiting good chemical stability in aqueous electrolyte environments, which is beneficial for maintaining the long-term stability of the electrode structure. Moreover, due to the high modulus of the polysaccharide backbone and its rich content of hydroxyl (-OH) functional groups that can be further modified, coupled with its low cost and environmental friendliness, it has been proven to be a functionalized platform molecule suitable for battery binder design.
[0054] In some embodiments, the polyionic liquid segment includes an aromatic group and a conductive polymeric group. The aromatic group includes at least one of phenyl, styrene, benzyl, or derivatives thereof, and the conductive polymeric group includes at least one of imidazolium, pyridinium, pyrrolidineium, or quaternary ammonium cations.
[0055] Because the polyionic liquid segments simultaneously include aromatic and conductive polymer groups, multiple monomers are not required for copolymerization; a single monomer can be used to achieve a good composite effect. It is worth noting that the benzene ring structure in the aromatic groups of the grafted side chains can combine with sp... 2 The carbon-based conductive material with a hybrid six-membered carbon ring generates π–π stacking interactions, thereby reducing the electron percolation threshold inside the electrode. Meanwhile, the conductive polymer groups located near the benzene ring endow the binder with self-healing capabilities and strong adhesion to various electrode components through dynamic and reversible electrostatic interactions, thus buffering the volume change stress during the charge and discharge process.
[0056] Further preferably, the conductive polymer group is located adjacent to the benzene ring, wherein the conductive polymer group is composed of an imidazolium cation and a bis(trifluoromethanesulfonyl)imide anion (TFSI). - Composed of various components, the adhesive possesses self-healing capabilities and strong adhesion to multiple electrode components through dynamic and reversible electrostatic interactions, thereby buffering the volume change stress during the charging and discharging process.
[0057] It is understandable that aromatic groups and conductive polymer groups work synergistically in structure, and the absence of either component would significantly weaken its overall function as a binder for zinc powder anodes. Based on the synergistic effect of multiple functional groups in the polysaccharide-based binder, zinc-based battery electrodes prepared using this binder exhibit significant improvements in mechanical stability, electrochemical cycle life, and high current density operation capability, outperforming zinc powder anode systems using zinc foil electrodes or commercial polymer binders. These performance improvements stem from the adaptive characteristics of this binder under actual battery operating conditions; its ion conductivity and mechanical strength can be simultaneously optimized during electrolyte swelling.
[0058] In some embodiments, the content ratio of polyionic liquid segments to polyacrylic acid segments ranges from (3~5):1. It is worth noting that, since the acrylic acid units, after copolymerization with hydrophobic monomers, are beneficial to improving the mechanical flexibility and adhesion of polysaccharide-based binders, while also improving polymerization efficiency and imparting a certain degree of hydrophilicity to the material. Polysaccharide-based binders with hydrophilic properties can undergo limited swelling in aqueous electrolyte environments, thereby providing channels for the transport of working ions and increasing zinc ion transport performance compared to traditional binders.
[0059] The ratio of polyionic liquid segments to polyacrylic acid segments can range from 3:1, 3.5:1, 4:1, 4.5:1, to 5:1. More preferably, the ratio is 4:1, where the polyacrylic acid segments and polyionic liquid segments achieve good synergistic effects. The resulting binder can achieve stable bonding in the electrolyte of zinc-ion batteries, ensuring excellent conductivity while also possessing high mechanical strength and the ability to self-heal without external stimulation.
[0060] This application also provides a method for preparing a polysaccharide-based binder, comprising the following steps: S100, dissolving polysaccharide in an ionic liquid and reacting it with an acyl bromide compound to obtain a bromine-containing initiator; S200, reacting the bromine-containing initiator, carbon disulfide, and a thiol compound under an alkaline environment to obtain a chain transfer agent; S300, quaternizing an N-substituted imidazole with a monomer including an aromatic group or its derivative group to obtain an ionic liquid monomer including an aromatic group; S400, mixing the chain transfer agent, ionic liquid monomer, acrylic monomer, and free radical polymerization initiator in the liquid phase to carry out a reversible addition-fragmentation chain transfer polymerization reaction to obtain an intermediate product; S500, subjecting the intermediate product to an anion exchange reaction with a bis(trifluoromethanesulfonyl)imide salt, collecting the precipitate, washing and drying it to obtain a polysaccharide-based binder, wherein the polysaccharide-based binder is grafted with polyionic liquid segments and polyacrylic acid segments.
[0061] Due to the strong hydrogen bond network and crystalline structure between natural polysaccharides such as chitin and cellulose, they are extremely difficult to dissolve or are insoluble in common water or organic solvents. Ionic liquids, as special molten salts composed of ions, can effectively break these hydrogen bonds, disrupt the regular arrangement of polysaccharides, and allow their molecular chains to fully unfold and dissolve, forming a homogeneous and stable solution. On the other hand, the dissolution process is not only a physical dispersion; ionic liquids can also interact with functional groups such as hydroxyl groups on the polysaccharide chains, activating the polysaccharide backbone and making the reaction sites on it easier to contact the grafting monomers, further improving the efficiency and uniformity of subsequent grafting reactions.
[0062] This application also provides the application of the aforementioned polysaccharide-based binder or the polysaccharide-based binder prepared by the aforementioned method as a binder for zinc-based negative electrode sheets in zinc-ion batteries. In other words, this application synthesizes a binder for zinc-based negative electrodes in zinc-ion batteries through graft polymerization. This application adopts a modular molecular engineering design strategy, with each structural unit being collaboratively designed to address different key issues faced by zinc-based negative electrodes, thereby achieving a high degree of integration of structure and function. The polysaccharide-based binder provided by this application can effectively bind various electrode components such as zinc powder and conductive agents, constructing a mechanically stable integrated electrode structure and forming continuous ion and electron transport channels.
[0063] This application provides an electrode paste comprising a polysaccharide-based binder and an organic solvent as described above, and further comprising at least one of zinc powder and a conductive agent. Using the polysaccharide-based binder provided in this application facilitates the preparation of a stable and processable electrode paste. Furthermore, the electrode paste containing the polysaccharide-based binder is suitable for various zinc powder electrode manufacturing processes, such as blade coating, spraying, and screen printing, exhibiting good adaptability.
[0064] In some embodiments, the conductive agent is at least one of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black. Selecting a suitable conductive agent is beneficial for obtaining an electrode paste with good operational stability.
[0065] In some embodiments, the organic solvent is at least one selected from N-methylpyrrolidone, acetone, dimethyl sulfoxide, and N,N-dimethylformamide. Choosing a suitable organic solvent is beneficial for obtaining an electrode paste with good stability in use.
[0066] In some embodiments, the mass ratio of zinc powder, conductive agent, and polysaccharide-based binder is (6~9):(0.5~2):(0.5~2). Selecting a suitable mass ratio of zinc powder, conductive agent, and polysaccharide-based binder is beneficial for obtaining electrode pastes with good performance stability.
[0067] In some embodiments, the electrode slurry comprises a polysaccharide-based binder, an organic solvent, zinc powder, and a conductive agent. The solid content of the electrode slurry is ≤60%, and the conductive agent is at least two of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black. Using a compounded conductive agent facilitates the construction of a multi-dimensional conductive network of points, lines, and surfaces, thereby increasing the conductivity of the electrode slurry. In other words, simultaneously using at least two types of granular conductive carbon black, one-dimensional tubular carbon nanotubes, and one-dimensional fibrous vapor-grown carbon fibers facilitates the construction of a three-dimensional network-like conductive framework. This provides support for the entire electrode structure while enhancing the integrity of the conductive network, thereby further improving the overall energy density of the battery when applied in a battery.
[0068] In some embodiments, when the conductive agent is two of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black, the conductive agent includes a first conductive agent and a second conductive agent, which are different from each other, and the mass ratio of the first conductive agent to the second conductive agent is 1:(0.5~2). Using a compounded conductive agent facilitates the construction of a multi-dimensional conductive network of points, lines, and surfaces, thereby increasing the conductivity of the electrode slurry. In other words, simultaneously using two types of granular conductive carbon black, one-dimensional tubular carbon nanotubes, and one-dimensional fibrous vapor-grown carbon fibers facilitates the construction of a three-dimensional network-like conductive framework. This provides support for the entire electrode structure while enhancing the integrity of the conductive network, thereby further improving the overall energy density of the battery when applied in a battery.
[0069] This application provides a battery electrode sheet comprising the electrode paste as described above. By using the polysaccharide-based binder and electrode paste provided in this application, it is advantageous to produce a battery electrode sheet that can be stably processed. Furthermore, using a battery electrode sheet with a highly conductive electrode paste is beneficial for reducing polarization and improving rate performance.
[0070] In some embodiments, the battery electrode sheet is prepared by: providing a current collector, coating an electrode slurry onto the current collector, drying the electrode slurry, and obtaining the battery electrode sheet. The current collector is aluminum foil, the drying temperature is 50°C to 100°C, and the drying time is 5 hours to 15 hours. It is understood that, due to the good self-healing ability and bonding properties of the polysaccharide-based binder, it exhibits universal adhesion to the current collector and various electrode components, thus protecting the zinc powder electrode from structural damage.
[0071] In some embodiments, the areal loading of zinc powder in the battery electrode is 4 mg / cm³. 2 ~24mg / cm 2It is understandable that when the areal loading of zinc powder is too high, it can easily lead to obstructed ion transport and / or electrode cracking, while when the areal loading of zinc powder is too low, it reduces the energy density of the battery. Therefore, when the areal loading of zinc powder is within a suitable range, it is beneficial to obtain battery electrodes with good electrochemical performance.
[0072] In some embodiments, the method for preparing the battery electrode sheet includes: providing a substrate, printing electrode paste onto the substrate, drying the electrode paste, and obtaining a screen-printed flexible battery electrode sheet. The preparation method satisfies at least one of the following conditions: the drying temperature is 50°C to 100°C; the drying time is 5 hours to 15 hours; and the substrate is at least one of leaves, thin wood chips, and polyimide film. Because the polysaccharide-based binder has good self-healing ability and bonding properties, and exhibits universal adhesion to the current collector and various electrode components, it can protect the zinc powder electrode from structural damage.
[0073] In some embodiments, the battery electrode preparation method includes: spraying an electrode slurry onto a polymer substrate, drying the electrode slurry to obtain a sprayed zinc-based battery electrode, and the preparation method satisfies at least one of the following conditions: the drying temperature is 50°C to 100°C; the drying time is 5 hours to 15 hours; and the polymer substrate is at least one of polyvinyl chloride film, polyethylene terephthalate film, and polyimide film. Because the polysaccharide-based binder has good self-healing ability and bonding performance, and exhibits universal adhesion to the current collector and various electrode components, it can protect the zinc powder electrode from structural damage.
[0074] This application also provides a battery, which includes at least one battery electrode as described above. By using the battery electrode provided in this application, it is beneficial to improve the energy density of the battery.
[0075] Example 1 A method for preparing a polysaccharide-based binder, electrode slurry, zinc-based battery electrode, and battery, comprising the following steps: (1) Synthesis of chain transfer agent: First, 3 g of chitin was dissolved in 150 g of 1-allyl-3-methylimidazolium bromide ionic liquid at 105 °C, and 159.3 g of 2-bromopropionyl bromide was added. The mixture was stirred at room temperature for 48 hours. The resulting solution was precipitated in water, and the product was dried at 60 °C to obtain the initiator. 2 g of the initiator was dissolved in 40 mL of dimethyl sulfoxide, while 225.5 mg of 1-butanethiol, 253 mg of triethylamine, and 571.1 mg of carbon disulfide were dissolved in 5 mL of dimethyl sulfoxide at room temperature. After 10 minutes, this solution was added to the initiator solution, and the mixture was stirred overnight. The resulting solution was precipitated in water to obtain the chain transfer agent.
[0076] (2) Synthesis of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride monomer: 8.24 g of 1-butylimidazolium and 11.02 g of 4-chloromethylstyrene monomer were dissolved in 30 mL of acetonitrile and stirred overnight at 45 °C. The resulting solution was precipitated in ethyl acetate to obtain 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride.
[0077] (3) Preparation of polysaccharide-based binder: 54 mg of chain transfer agent, 5.54 g of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride, 0.36 g of acrylic acid, 1.64 mg of azobisisobutyronitrile, and 5 mL of N,N-dimethylformamide were added to a flask and immersed in an oil bath at 70 °C under vacuum. After 5 days, the polymerization was terminated, and the solution was precipitated in ethyl acetate. The product polymer A was collected and vacuum dried overnight at 60 °C. 2 g of polymer A was dissolved in deionized water. Subsequently, 2.05 g of lithium bis(trifluorosulfonyl)imide was dissolved in water and added to the polymer A solution. The precipitate was collected, washed thoroughly with water, and the final product polysaccharide-based binder (i.e., chitosan-based binder) was collected and vacuum dried overnight at 60 °C.
[0078] (4) Preparation of electrode slurry and zinc-based battery electrode: 3.2g zinc powder, 0.4g chitosan-based binder, 0.2g carbon nanotubes and 0.2g vapor-grown carbon fibers were dispersed in 3.75mL of N-methylpyrrolidone to prepare electrode slurry. Zinc-based battery electrode was prepared by blade coating with 20μm thick aluminum foil as current collector, and then dried overnight at 60℃.
[0079] (5) Battery preparation: CR2032 button cells were assembled in air using glass fiber as the separator and 4 mol / kg zinc trifluoromethanesulfonate solution as the electrolyte for electrochemical testing.
[0080] Example 2 A method for preparing a polysaccharide-based adhesive film includes the following steps: (1) Synthesis of chain transfer agent: First, 3 g of chitin was dissolved in 150 g of 1-allyl-3-methylimidazolium bromide ionic liquid at 105 °C, and 159.3 g of 2-bromopropionyl bromide was added. The mixture was stirred at room temperature for 48 hours. The resulting solution was precipitated in water, and the product was dried at 60 °C to obtain the initiator. 2 g of the initiator was dissolved in 40 mL of dimethyl sulfoxide, while 225.5 mg of 1-butanethiol, 253 mg of triethylamine, and 571.1 mg of carbon disulfide were dissolved in 5 mL of dimethyl sulfoxide at room temperature. After 10 minutes, this solution was added to the initiator solution, and the mixture was stirred overnight. The resulting solution was precipitated in water to obtain the chain transfer agent.
[0081] (2) Synthesis of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride monomer: 8.24 g of 1-butylimidazolium and 11.02 g of 4-chloromethylstyrene monomer were dissolved in 30 mL of acetonitrile and stirred overnight at 45 °C. The resulting solution was precipitated in ethyl acetate to obtain 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride.
[0082] (3) Preparation of polysaccharide-based binder: 54 mg of chain transfer agent, 5.54 g of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride, 0.36 g of acrylic acid, 1.64 mg of azobisisobutyronitrile, and 5 mL of N,N-dimethylformamide were added to a flask and immersed in an oil bath at 70 °C under vacuum. After 5 days, the polymerization was terminated. The solution was precipitated in ethyl acetate, and the product polymer A was collected and vacuum dried overnight at 60 °C. 2 g of polymer A was dissolved in deionized water. Subsequently, 2.05 g of lithium bis(trifluorosulfonyl)imide was dissolved in water and added to the polymer A solution. The precipitate was collected, thoroughly washed with water, and the final product polysaccharide-based binder was collected and vacuum dried overnight at 60 °C.
[0083] (4) Preparation of polysaccharide-based adhesive film: 1g of polysaccharide-based adhesive is placed in a mold and pressed into a film of 0.22mm to prepare polysaccharide-based adhesive film.
[0084] Example 3 The difference between Example 3 and Example 2 is that step (4) is: 1g of polysaccharide-based adhesive is placed in a mold and pressed into a film of 0.22mm. Then the film is immersed in a 4mol / kg zinc trifluoromethanesulfonate solution at room temperature for 24h to obtain a swollen polysaccharide-based adhesive film.
[0085] Example 4 The difference between Example 4 and Example 1 is that chitosan is replaced with cellulose.
[0086] Example 5 The difference between Example 5 and Example 1 is that chitin is replaced with starch.
[0087] Example 6 The difference between Example 6 and Example 1 is that steps (4) and (5) are replaced by: dispersing 3.2g zinc powder, 0.4g polysaccharide-based binder, 0.2g carbon nanotubes, and 0.2g vapor-grown carbon fibers in 18.75mL of N-methylpyrrolidone to prepare a screen-printed electrode paste. Using a screen printing process with fresh leaves as the substrate, a flexible battery electrode was prepared and then dried at 60°C for 8 hours.
[0088] Example 7 The difference between Example 7 and Example 6 is that fresh leaves are replaced with thin wood chips.
[0089] Example 8 The difference between Example 8 and Example 6 is that fresh leaves are replaced with a polyimide film.
[0090] Example 9 The difference between Example 9 and Example 1 is that steps (4) and (5) are replaced by: dispersing 3.2g of zinc powder, 0.4g of polysaccharide-based binder, 0.2g of carbon nanotubes, and 0.2g of vapor-grown carbon fibers in 37.5mL of N-methylpyrrolidone to prepare a sprayed electrode slurry. A zinc-based battery electrode is prepared using a spraying process with a polyvinyl chloride film as a substrate, and then dried at 60°C for 6 hours.
[0091] Comparative Example 1 A method for preparing a zinc-based battery electrode and battery includes the following steps: dispersing 3.2g of zinc powder, 0.4g of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), 0.2g of carbon nanotubes, and 0.2g of vapor-grown carbon fibers in 3.75mL of N-methylpyrrolidone to prepare an electrode slurry. A zinc-based battery electrode is prepared using a doctor blade coating process with a 20μm thick aluminum foil as the current collector, and then dried overnight at 60℃. A CR2032 button cell is assembled in air using glass fiber as the separator and a 4mol / kg zinc trifluoromethanesulfonate solution as the electrolyte for electrochemical testing.
[0092] Comparative Example 2 A method for preparing a battery includes the following steps: using a 100μm high-purity zinc foil with a surface polished by 2000-mesh sandpaper as the negative electrode, glass fiber as the separator, and a 4mol / kg zinc trifluoromethanesulfonate solution as the electrolyte, assembling a CR2032 button cell in air for electrochemical testing.
[0093] Comparative Example 3 A method for preparing a zinc-based battery electrode and battery includes the following steps: dispersing 3.2 g of zinc powder, 0.4 g of polyvinylidene fluoride (PVDF) powder, 0.2 g of carbon nanotubes, and 0.2 g of vapor-grown carbon fibers in 3.75 mL of N-methylpyrrolidone to prepare an electrode slurry. A zinc-based battery electrode is prepared using a doctor blade coating process with a 20 μm thick aluminum foil as the current collector, followed by drying at 60 °C overnight. A CR2032 coin cell is assembled in air using glass fiber as the separator and a 4 mol / kg zinc trifluoromethanesulfonate solution as the electrolyte for electrochemical testing.
[0094] Comparative Example 4 A method for preparing a zinc-based battery electrode and battery includes the following steps: dispersing 3.2g zinc powder, 0.267g carboxymethyl cellulose (CMC), 0.133g styrene-butadiene rubber (SBR), 0.2g carbon nanotubes, and 0.2g vapor-grown carbon fibers in 3.74mL of pure water to prepare an electrode slurry. A zinc-based battery electrode is prepared using a doctor blade coating process with a 20μm thick aluminum foil as the current collector, and then dried overnight at 60℃. A CR2032 button cell is assembled in air using glass fiber as the separator and a 4mol / kg zinc trifluoromethanesulfonate solution as the electrolyte for electrochemical testing.
[0095] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that step (3) is as follows: 54 mg of chain transfer agent, 5.54 g of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride, 1.8 g of acrylic acid, 1.64 mg of azobisisobutyronitrile and 5 mL of N,N-dimethylformamide are added to a flask, immersed in an oil bath at 70 °C under vacuum, and the polymerization is terminated after 5 days. The solution is precipitated in ethyl acetate, and the product polymer 2 is collected and vacuum dried overnight at 60 °C. 2 g of polymer 2 is dissolved in deionized water. Subsequently, 2.05 g of lithium bis(trifluorosulfonyl)imide is dissolved in water and added to the polymer 2 solution. The precipitate is collected, thoroughly washed with water, and the final product binder 2 is collected and vacuum dried overnight at 60 °C.
[0096] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that step (3) is as follows: 54 mg of chain transfer agent, 2.08 g of styrene, 0.36 g of acrylic acid, 1.64 mg of azobisisobutyronitrile and 5 mL of N,N-dimethylformamide are added to a flask, immersed in an oil bath at 70 °C and vacuumed. After 5 days, the polymerization is terminated, the solution is precipitated in ethyl acetate, the product binder 3 is collected, and it is vacuum dried at 60 °C overnight.
[0097] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that step (3) is as follows: 5.54 g of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride, 0.36 g of acrylic acid, 1.64 mg of azobisisobutyronitrile, and 5 mL of N,N-dimethylformamide are added to a flask, immersed in an oil bath at 70 °C under vacuum, and the polymerization is terminated after 5 days. The solution is precipitated in ethyl acetate, and the product polymer 3 is collected and vacuum dried overnight at 60 °C. 2 g of polymer 3 is dissolved in deionized water. Subsequently, 2.05 g of lithium bis(trifluorosulfonyl)imide is dissolved in water and added to the polymer 3 solution. The precipitate is collected, thoroughly washed with water, and the final product binder 4 is collected and vacuum dried overnight at 60 °C.
[0098] Comparative Example 8 The difference between Comparative Example 8 and Example 1 is that step (3) is as follows: 54 mg of chain transfer agent, 6.925 g of 1-[(4-vinylphenyl)methyl]-3-butyl-imidazolium chloride, 1.64 mg of azobisisobutyronitrile and 5 mL of N,N-dimethylformamide are added to a flask, immersed in an oil bath at 70 °C under vacuum, and the polymerization is terminated after 5 days. The solution is precipitated in ethyl acetate, and the product polymer 4 is collected and vacuum dried overnight at 60 °C. 2 g of polymer 4 is dissolved in deionized water. Subsequently, 2.05 g of lithium bis(trifluorosulfonyl)imide is dissolved in water and added to the polymer 4 solution. The precipitate is collected, thoroughly washed with water, and the final product binder 5 is collected and vacuum dried overnight at 60 °C.
[0099] Comparative Example 9 The difference between Comparative Example 9 and Example 1 is that step (4) involves dispersing 3.2 g of zinc powder, 0.4 g of chitosan-based binder, and 0.4 g of carbon nanotubes in 3.75 mL of N-methylpyrrolidone to prepare an electrode slurry. A zinc-based battery electrode was prepared using a doctor blade coating process with a 20 μm thick aluminum foil as the current collector, and then dried overnight at 60°C.
[0100] Performance testing The battery cycle performance was tested using the Xinwei and Landian battery testing systems, the electrochemical performance was tested using the Shanghai Chenhua electrochemical workstation, and the tensile and adhesive properties were tested using a universal tensile testing machine.
[0101] The elastomer structure composition of the polysaccharide-based adhesives prepared in Example 1 and Comparative Examples 5-8 was statistically analyzed, and the statistical results are shown in Table 1. In Table 1, “√” represents the presence of the relevant structure and “×” represents the absence of the relevant structure.
[0102] Table 1. Structural composition of polysaccharide-based binder elastomers
[0103] The performance of the polysaccharide-based adhesives prepared in Example 1 and Comparative Examples 5-8 was statistically analyzed, and the results are shown in Table 1. In Table 1, “√” indicates that the relevant performance is present, and “×” indicates that the relevant performance is not present.
[0104] Table 2. Performance Tests of Polysaccharide-Based Binders
[0105] As shown in Tables 1 and 2, only when the polysaccharide-based binder contains the polysaccharide backbone, conductive polymer groups, styrene groups, and acrylic groups can the polysaccharide-based binder simultaneously achieve electrolyte insolubility, high strength, room temperature self-healing, and universal adhesion in zinc-based battery electrodes.
[0106] Table 3 shows the relevant preparation conditions and parameters of the products prepared in Examples 1, 6-9 and Comparative Example 10, and their electrochemical performance was tested.
[0107] Table 3. Relevant preparation condition parameters for the products prepared in some examples and comparative examples.
[0108] Electrochemical performance testing (1) Sample preparation: The zinc-based battery electrode prepared in Example 1 was used as the negative electrode to assemble aqueous zinc-ion symmetric cells, aqueous zinc-ion asymmetric cells, and aqueous zinc-ion full cells, and electrochemical performance was tested. The zinc-based battery electrodes prepared by Comparative Example 1 and Comparative Example 2 were assembled into aqueous zinc-ion symmetric cells, aqueous zinc-ion asymmetric cells, and aqueous zinc-ion full cells, respectively. The aqueous zinc-ion symmetric cells assembled by the zinc-based battery electrodes prepared by Comparative Example 3 and Comparative Example 9 were used as control groups.
[0109] (2) Cycle life test of aqueous zinc-ion symmetric battery: The zinc-based battery electrodes prepared in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 9 were used as positive and negative electrodes, respectively. A zinc trifluoromethanesulfonate solution with a concentration of 4 mol / kg was used as the electrolyte, and glass fiber was used as the separator to assemble a button-type aqueous zinc-ion symmetric battery. The current density was 1 mA cm⁻¹. -2 The single-cycle deposition / stripping time was 1 hour / 1 hour, and the cycle life of the aqueous zinc-ion symmetric cell was tested. The test results are as follows: Figure 7 and Figure 18 As shown, the cycle life of the aqueous zinc-ion symmetric battery (Zn||Zn battery) prepared by Example 1 is about 400 hours, while the cycle life of the Zn||Zn batteries prepared by Comparative Examples 1 to 3 is less than 100 hours. The Zn||Zn battery prepared by Comparative Example 9 has a very large polarization voltage at the beginning of cycling, indicating that the Zn||Zn battery prepared by Example 1 has good cycle stability. Furthermore, vapor-grown carbon fibers play an indispensable role in achieving the long cycle life of zinc-based battery electrodes. At the same time, the use of long-range conductive agents (vapor-grown carbon fibers) and short-range conductive agents (carbon nanotubes) is beneficial to increasing the number of electron transport paths during battery operation.
[0110] (3) Cycle life test of aqueous zinc-ion full battery: The zinc-based battery electrodes prepared in Example 1 and Comparative Example 1 were used as negative electrodes, and V2O5 electrodes (V2O5, carbon nanotubes and bacterial cellulose nanofibers were mixed with water in a mass ratio of 75:20:5, filtered on a stainless steel mesh and dried to prepare the positive electrode) were used as positive electrodes. A zinc trifluoromethanesulfonate solution with a concentration of 4 mol / kg was used as the electrolyte, and glass fiber was used as the separator to assemble a button-type aqueous zinc-ion full battery (Zn||V2O5 battery). The current density was 1 A / g (based on the active material), and the operating voltage range was 0.2V~1.6V. The cycle life of the aqueous zinc-ion full battery was tested. The test results are as follows: Figure 9 As shown, the Zn||V₂O₅ battery prepared in Example 1 still retains 10⁹ mAh g⁻¹ after 800 cycles. -1 The capacity of the Zn||V2O5 battery in Comparative Example 1 dropped sharply to near zero after about 400 cycles.
[0111] (4) Specific capacity test of aqueous zinc-ion full battery: The zinc-based battery electrodes prepared in Example 1 and Comparative Example 1 were used as negative electrodes, and V2O5 electrodes (V2O5, carbon nanotubes, and bacterial cellulose nanofibers were mixed with water in a mass ratio of 75:20:5, filtered on a stainless steel mesh, and dried to prepare the positive electrode) were used as positive electrodes. A zinc trifluoromethanesulfonate solution with a concentration of 4 mol / kg was used as the electrolyte, and glass fiber was used as the separator to assemble a button-type aqueous zinc-ion full battery (Zn||V2O5 battery). The current densities were 0.1 A / g, 0.2 A / g, 0.5 A / g, 1 A / g, 2 A / g, and 3 A / g (based on the active material), and the working voltage range was 0.2 V to 1.6 V. The specific capacity of the aqueous zinc-ion full battery was tested. The test results are as follows: Figure 10 As shown, the Zn||V₂O₅ battery prepared in Example 1 consistently exhibits a significantly higher specific capacity at current densities above 0.5 A / g. At a current density of 3 A / g, the specific discharge capacity of the Zn||V₂O₅ battery prepared in Example 1 is 132 mAh g. -1 The specific discharge capacity of Comparative Example 1 was only 102 mAh g. -1 When the current density was 0.1 A / g, the Zn||V2O5 battery prepared in Example 1 recovered its initial capacity and operated stably for the next dozens of cycles, while the Zn||V2O5 battery in Comparative Example 1 showed rapid capacity decay.
[0112] (5) Deposition stripping cycle efficiency test: The zinc-based battery electrodes prepared in Example 1, Comparative Example 1, and Comparative Example 2 were used as negative electrodes, copper foil as positive electrodes, and zinc trifluoromethanesulfonate solution with a concentration of 4 mol / kg as electrolyte. Glass fiber was used as the separator to assemble a button-type aqueous zinc-ion asymmetric battery (Zn||Cu asymmetric battery). The efficiency was tested at 1 mA cm⁻¹. -2 At the given current density, the deposition time per cycle is 1 hour, and the stripping cutoff voltage is 0.8V (relative to Zn / Zn). 2+ The deposition stripping cycle efficiency was tested. The test results are as follows: Figure 8 As shown, the average coulombic efficiency of the Zn||Cu asymmetric battery prepared by Example 1 is about 99.51%, and the number of cycles exceeds 300. In contrast, the average coulombic efficiency of the Zn||Cu asymmetric batteries prepared by Comparative Examples 1 and 2 is less than 99%, and the number of cycles does not exceed 60. This indicates that the zinc ions in the zinc-based battery electrode prepared by Example 1 have good deposition and stripping cycle efficiency.
[0113] (6) Photographs of the aqueous zinc-ion soft-pack battery: The zinc-based battery electrode sheet prepared in Example 1 was used as the negative electrode, and a V2O5 electrode (V2O5, carbon nanotubes and bacterial cellulose nanofibers were mixed with water in a mass ratio of 75:20:5, filtered on a stainless steel mesh and dried to make the positive electrode) was used as the positive electrode. A zinc trifluoromethanesulfonate solution with a concentration of 4 mol / kg was used as the electrolyte, and glass fiber was used as the separator. An aqueous zinc-ion soft-pack battery (Zn||V2O5 battery) was assembled. The photographs are shown below. Figure 11 As shown.
[0114] Tensile property test (1) Tensile strength test before and after self-healing: The polysaccharide-based adhesive film prepared in Example 2 was subjected to stress-strain mechanical testing at room temperature with a tensile speed of 50 mm / min. The tensile strength of the film was tested in its original state, after 1 h of self-healing, after 4 h of self-healing, after 8 h of self-healing, and after 12 h of self-healing. The test results curves are shown below. Figure 3 As shown, the polysaccharide-based binder film achieved near-complete self-healing (approximately >95%) within 12 hours, indicating that the polysaccharide-based binder has excellent self-healing ability, thus maintaining the structural integrity of the zinc-based battery electrode during the cycling process of aqueous zinc-ion batteries.
[0115] (2) Tensile strength test: The polysaccharide-based adhesive films prepared in Examples 2, 3, and Comparative Examples 5-8 were subjected to stress-strain mechanical tests at room temperature, with a tensile speed of 50 mm / min. The test results are as follows: Figure 14As shown, Comparative Example 5 exhibits high tensile strength but low strain; Comparative Example 6 displays low-strength brittleness and cannot be tested; Comparative Examples 7 and 8 exhibit high strain but low tensile strength. In contrast, the polysaccharide-based binder film of Example 2 exhibits high stress and strain, reaching a stable equilibrium state, indicating that the polysaccharide-based binder has good tensile strength and is suitable as a binder for use in the battery field. Based on this, as... Figure 15 As shown, the mechanical properties of Example 3 are further improved compared to Example 2, indicating that polysaccharide-based binders with swelling properties are beneficial to improving the mechanical properties of the binder.
[0116] Adhesion performance test (1) Peel strength test: At room temperature, the zinc-based battery electrodes prepared in Example 1 and Comparative Example 1 were subjected to a peel test at 180° with a tensile speed of 50 mm / min. The test results are as follows: Figure 6 As shown, the zinc-based battery electrode prepared in Example 1 exhibits a peel strength greater than 3.26 ± 0.78 N / cm, and no interfacial or cohesive damage occurs on the electrode surface. In contrast, the zinc-based battery electrode prepared in Comparative Example 1 has an extremely low peel strength of only 0.05 N / cm, and the electrode surface is damaged. This indicates that the polysaccharide-based binder synthesized in Example 1 possesses rapid self-healing ability and good bonding performance, which is beneficial for increasing the structural stability of the zinc-based battery electrode.
[0117] (2) Universal adhesion test of various electrode components: At room temperature, universal adhesion tests were conducted on various types of electrode components of the zinc-based battery electrode sheet prepared in Example 1. The test materials were polytetrafluoroethylene, aluminum foil, zinc foil, graphite and alumina. The test results are as follows: Figure 20 As shown, the zinc-based battery electrode sheet prepared in Example 1 has good adhesion to various types of electrode components.
[0118] (3) Ultrasonic stability test in electrolyte: At room temperature, the zinc-based battery electrodes prepared in Example 1 and Comparative Example 1 were subjected to ultrasonic stability tests in electrolyte. The test results are as follows: Figure 21 As shown, the zinc-based battery electrode prepared in Comparative Example 1 was completely peeled off from the current collector after 5 minutes, while the zinc-based battery electrode prepared in Example 1 still maintained the complete electrode structure.
[0119] pass Figures 1-26The test results show that the polymer grafted with polyacrylic acid segments alone (Comparative Example 5) dissolves in the electrolyte of zinc-ion batteries and cannot be used as a binder for zinc powder negative electrodes. The polymer grafted with polyionic liquid segments alone (Comparative Example 8), although insoluble in water and possessing good conductivity, has weak strength due to the lack of an additional hydrogen bond network provided by the polyacrylic acid segments, and cannot achieve self-healing. Comparing Examples 1 and 4-5, it is evident that the polysaccharide-based binder prepared using chitin, cellulose, and starch as the polysaccharide backbone exhibits good stability and lifespan when applied to batteries.
[0120] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.
Claims
1. A polysaccharide-based binder, characterized in that, The polysaccharide-based binder comprises: (a) Polysaccharide backbone; (b) Grafted side chains, wherein the grafted side chains are grafted onto the polysaccharide backbone, and the grafted side chains include a first grafted side chain and a second grafted side chain, wherein the first grafted side chain includes a polyionic liquid segment and the second grafted side chain includes a polyacrylic acid segment.
2. The polysaccharide-based binder according to claim 1, characterized in that, The polysaccharide-based binder satisfies at least one of the following conditions: (a) The polyionic liquid segment comprises an aromatic group and a conductive polymeric group, wherein the aromatic group comprises at least one of phenyl, styryl, benzyl or a derivative thereof, and the conductive polymeric group comprises at least one of imidazolium, pyridinium, pyrrolidineium or quaternary ammonium cations; (b) The content ratio of the polyionic liquid segment to the polyacrylic acid segment is in the range of (3~5):1; (c) The polysaccharide backbone is at least one of chitin backbone, cellulose backbone, and starch backbone.
3. A method for preparing a polysaccharide-based binder, characterized in that, Including the following steps: S100. Dissolve polysaccharides in ionic liquids and react them with acyl bromide compounds to prepare bromine-containing initiators; S200. Under alkaline conditions, the bromine-containing initiator, carbon disulfide, and thiol compound are reacted to prepare a chain transfer agent. S300: An ionic liquid monomer containing an aromatic group is prepared by quaternizing an N-substituted imidazole with a monomer including an aromatic group or its derivative group. S400, the chain transfer agent, the ionic liquid monomer, the acrylic monomer and the free radical polymerization initiator are mixed in the liquid phase to carry out a reversible addition-fragmentation chain transfer polymerization reaction to obtain an intermediate product; S500. The intermediate product is subjected to anion exchange reaction with bis(trifluoromethanesulfonyl)imide salt, the precipitate is collected, washed and dried to obtain polysaccharide-based binder.
4. The application of the polysaccharide-based binder according to any one of claims 1 to 2 or the polysaccharide-based binder prepared by the preparation method according to claim 3 as a zinc-based negative electrode binder for zinc-ion batteries.
5. An electrode paste, characterized in that, The electrode paste comprises the polysaccharide-based binder and organic solvent as described in claim 1 or 2, and the electrode paste further comprises at least one of zinc powder and conductive agent.
6. The electrode paste according to claim 5, characterized in that, At least one of the following conditions must be met: (a) The conductive agent is at least one of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black; (b) The organic solvent is at least one of N-methylpyrrolidone, acetone, dimethyl sulfoxide, and N,N-dimethylformamide; (c) The mass ratio of the zinc powder, the conductive agent and the polysaccharide-based binder is (6~9):(0.5~2):(0.5~2).
7. The electrode paste according to claim 5 or 6, characterized in that, The electrode paste comprises the polysaccharide-based binder, the organic solvent, the zinc powder, and the conductive agent; the solid content of the electrode paste is ≤60%; the conductive agent is at least two of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black; and When the conductive agent is two of carbon nanotubes, vapor-grown carbon fibers, and conductive carbon black, the conductive agent includes a first conductive agent and a second conductive agent. The first conductive agent and the second conductive agent are different, and the mass ratio of the first conductive agent to the second conductive agent is 1:(0.5~2).
8. A battery electrode, characterized in that, Includes the dried electrode slurry as described in any one of claims 5 to 7.
9. The battery electrode according to claim 8, characterized in that, The battery electrode is prepared by any of the following methods: (a) Provide a current collector, coat the electrode slurry onto the current collector, and dry the electrode slurry to obtain the battery electrode sheet, wherein the current collector is aluminum foil, the drying temperature is 50°C to 100°C, and the drying time is 5h to 15h; (b) A substrate is provided, the electrode paste is printed on the substrate, and the electrode paste is dried to obtain a screen-printed flexible battery electrode sheet. The drying temperature is 50°C to 100°C, and the drying time is 5h to 15h. The substrate is at least one of leaves, thin wood chips, and polyimide film. (c) After the electrode slurry is sprayed onto the polymer substrate, the electrode slurry is dried to obtain a sprayed zinc-based battery electrode sheet. The drying temperature is 50°C to 100°C and the drying time is 5h to 15h. The polymer substrate is at least one of polyvinyl chloride film, polyethylene terephthalate film, and polyimide film.
10. A battery, characterized in that, It includes at least one battery electrode as described in claim 8 or 9.