Pole piece and preparation method and application thereof

Abstract

The invention discloses a pole piece and a preparation method and application thereof, and belongs to the technical field of new energy storage. The preparation method of the pole piece comprises the following steps: mixing an active substance and a conductive agent to form a first mixture; mixing the first mixture with a composite binder, and performing fibrosis treatment to form a second mixture; the composite binder comprises polyhydroxyalkanoate and a non-biodegradable binder; forming a film from the second mixture to form an active layer; and compounding the active layer with a current collector to form the pole piece, in the composite binder, the mass ratio of the polyhydroxyalkanoate is 5%-80%. The polyhydroxyalkanoate and the non-biodegradable binder are compounded to serve as the binder of the active layer, the dosage of the binder is optimized, the film forming property of the active layer can be improved and the loading capacity of the active substance of the pole piece can be improved by forming the film through a dry process, and the cycle life of the prepared pole piece is remarkably prolonged when the prepared pole piece is used for the battery.

Description

Technical Field

[0001] The present application relates to the field of new energy storage technology, and in particular to a pole piece and its preparation method and application. Background Art

[0002] Zinc-manganese batteries have the advantages of high safety, low cost, environmental friendliness, high energy density, moderate operating voltage and long service life. They are widely used in consumer electronics, medical equipment, energy storage systems, military and aerospace, transportation, industry and other fields.

[0003] The positive and negative electrodes of traditional zinc-manganese batteries are mostly produced using a wet process. First, the active material, conductive agent, binder, and solvent are mixed to prepare a slurry, which is then coated on the current collector to form an active layer. When using the wet process, if the active material loading is too high, it is easy to fall off the current collector or crack. Therefore, the active material loading of the electrode plates prepared by the wet process is generally not high. During the charge and discharge process, the effective amount of active material on the positive and negative current collectors that dissolves into the electrolyte is quite limited. The effective amount of manganese or zinc ions that migrate to the active material on the current collector is also insufficient, which seriously degrades the battery's cycle performance. Summary of the Invention

[0004] Based on this, the main purpose of this application is to provide a method for preparing an electrode, using a composite of polyhydroxyalkanoate and non-biodegradable adhesive as the binder for the active layer, and optimizing its dosage. By forming the film through a dry process, the film-forming property of the active layer can be improved, and the loading amount of the active material of the electrode can be increased. The prepared electrode has a significantly improved cycle life for the battery.

[0005] The first aspect of the present application provides a method for preparing a pole piece, comprising the following steps:

[0006] mixing the active material and the conductive agent to form a first mixture;

[0007] The first mixture and a composite binder are mixed and subjected to a fiberizing treatment to form a second mixture; the composite binder comprises polyhydroxyalkanoate and a non-biodegradable binder;

[0008] forming the second mixture into a film to form an active layer;

[0009] Compounding the active layer with the current collector to form the pole piece;

[0010] In the composite binder, the mass proportion of polyhydroxyalkanoate is 5%-80%.

[0011] In some embodiments, one or more of the following conditions are met:

[0012] (1) The electrode is a positive electrode or a negative electrode;

[0013] (2) The non-biodegradable binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene oxide and cellulose binder;

[0014] (3) The conductive agent includes at least one of Super-Li, activated carbon, carbon nanotubes, acetylene black, Ketjen black and graphite;

[0015] (4) The average molecular weight of the polyhydroxyalkanoate is 100,000 to 3,000,000;

[0016] (5) The film forming method includes at least one of roll film forming, extrusion film forming, hot pressing film forming and dry spray film forming.

[0017] In some embodiments, one or more of the following conditions are met:

[0018] (1) The active material of the positive electrode plate includes at least one of manganese dioxide, manganese trioxide and manganese tetraoxide;

[0019] (2) The active material of the negative electrode plate includes zinc metal or manganese metal;

[0020] (3) The non-biodegradable binder includes polytetrafluoroethylene and cellulose binder;

[0021] (4) The cellulose binder includes at least one of sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, microcrystalline cellulose and hydroxyethyl cellulose;

[0022] (5) The conditions for the roll-pressing film formation include: pressure 1T-4T; temperature 80°C-120°C.

[0023] In some embodiments, the mass ratio of the active material to the conductive agent is (4-10): (1-6); the mass ratio of the active material to the composite binder is (3-15):1.

[0024] In some embodiments, the active layer has a thickness of 100 μm to 1000 μm;

[0025] In the active layer, the mass proportion of the active material is 50%-90%.

[0026] The second aspect of the present application provides a pole piece prepared by the preparation method described in the first aspect.

[0027] A third aspect of the present application provides a pole piece, comprising a current collector and an active layer disposed on a surface of the current collector;

[0028] The active layer includes active material, conductive agent and composite binder;

[0029] The composite binder includes polyhydroxyalkanoate and non-biodegradable binder;

[0030] In the composite binder, the mass proportion of polyhydroxyalkanoate is 5%-80%.

[0031] In some embodiments, the dry film forming process includes at least one of roll film forming, extrusion film forming, hot pressing film forming, and dry spray film forming.

[0032] The fourth aspect of the present application provides the use of the electrode described in the second or third aspect in a battery or an electrical device.

[0033] The fifth aspect of the present application provides a battery comprising the electrode described in the second or third aspect.

[0034] The sixth aspect of the present application provides an electrical device comprising the electrode described in the second or third aspect, or the battery described in the fifth aspect.

[0035] Beneficial effects of this application:

[0036] 1. This application uses a composite of polyhydroxyalkanoate and non-biodegradable binder as the binder for the active layer, and optimizes its dosage. Through dry film formation, the film-forming properties of the active layer can be improved, and the loading amount of active substances in the electrode can be increased. The prepared electrode has a significantly improved cycle life for batteries.

[0037] 2. This application adopts a dry process, which does not require the use of solvents or solvent recovery. Compared with the wet process, it is more environmentally friendly, clean and economical. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of this application clearer and to provide a more thorough and comprehensive understanding of the disclosure of this application, the technical solutions of this application will be described clearly and completely below in conjunction with specific embodiments of this application. The described embodiments are only a portion of the embodiments of this application, not all of them.

[0039] The following is a detailed description of the implementation of this application. This embodiment is implemented based on the technical solution of this application, and provides a detailed implementation method and specific operation process, but the protection scope of this application is not limited to the following embodiment.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] the term

[0042] Unless otherwise specified or incompatible therewith, terms and phrases used in this application shall have the following meanings:

[0043] In this application, "a plurality of" or "a plurality of" refers to a number greater than or equal to 2 unless otherwise specified. For example, "at least one" or "at least one" means one or more than or equal to two.

[0044] In this application, "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0045] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0046] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is deemed to be continuous and includes the two numerical endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. "Numerical interval" is broadly allowed to include numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0047] In this application, unless otherwise specified, temperature parameters may be either constant temperature or fluctuating within a certain temperature range. It should be understood that constant temperature processing allows for temperature fluctuations within the precision range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0048] Unless otherwise specified, the percentage contents mentioned in this application refer to mass percentage for solid-liquid mixture and solid-solid mixture, and refer to volume percentage for liquid-liquid mixture.

[0049] In this application, temperature parameters, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control. The room temperature referred to in this application refers to 0-40°C, preferably 10-35°C, and more preferably 20-30°C.

[0050] When using a wet process to prepare electrodes, if the active material loading is too high, it is easy to fall off the current collector or cracks will occur. Therefore, the active material loading of the electrodes prepared by the wet process is usually not high. During the charge and discharge process, the effective amount of active materials on the positive and negative current collectors dissolved into the electrolyte is quite limited, and the effective amount of manganese ions or zinc ions migrating to the active materials on the current collector is also insufficient. This makes it difficult for the battery to fully demonstrate its due performance and the cycle performance is seriously degraded.

[0051] Based on this, the first aspect of the present application provides a method for preparing a pole piece, comprising the following steps:

[0052] mixing the active material and the conductive agent to form a first mixture;

[0053] The first mixture and a composite binder are mixed and subjected to a fiberizing treatment to form a second mixture; the composite binder comprises polyhydroxyalkanoate and a non-biodegradable binder;

[0054] forming the second mixture into a film to form an active layer;

[0055] Compounding the active layer with the current collector to form the pole piece;

[0056] In the composite binder, the mass proportion of polyhydroxyalkanoate is 5%-80%.

[0057] This application uses a composite of polyhydroxyalkanoate and non-biodegradable binder as the binder for the active layer, and optimizes its dosage. Through dry film formation, the film-forming properties of the active layer can be improved, and the loading amount of active substances in the electrode can be increased. The prepared electrode has a significantly improved cycle life for batteries, and does not require the use of solvents or solvent recovery. Compared with the wet process, it is more environmentally friendly, clean and economical.

[0058] Polyhydroxyalkanoates, as biodegradable polyesters, are rich in hydroxyl groups and have good adhesion to current collectors and active substances. However, the processing window of polyhydroxyalkanoates is narrow, and crystallization still occurs after processing, resulting in post-crystallization. Therefore, when dry-film-forming is performed alone, the film-forming property is poor and the film-forming quality cannot be guaranteed. The inventors have found that by combining polyhydroxyalkanoates with non-biodegradable binders such as polytetrafluoroethylene, the post-crystallization and film-forming properties can be greatly improved, the film-forming quality can be guaranteed, and the corresponding battery has a significantly improved cycle life. The reason may be that the addition of the non-biodegradable binder reduces the regularity of the polyhydroxyalkanoate molecular chain through intermolecular interaction, thereby reducing the crystallinity of the polyhydroxyalkanoate and improving the processability of the polyhydroxyalkanoate. In addition, by combining polyhydroxyalkanoates and non-biodegradable binders, the performance advantages of the two can be combined, and synergistic synergy can be achieved to obtain a better cycle life than using polyhydroxyalkanoates or non-biodegradable binders alone.

[0059] In a specific example, in the composite binder, the mass proportion of polyhydroxyalkanoate can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0060] In a specific example, the electrode is a positive electrode or a negative electrode.

[0061] In the present application, the type of active material is not particularly limited, and the corresponding active material can be selected according to the required type of battery and type of electrode. For example, when preparing a positive electrode sheet for a lithium-ion battery, the active material can be selected from at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel cobalt manganese ternary material, and lithium nickel cobalt aluminum oxide; when preparing a negative electrode sheet for a lithium-ion battery, the active material can be selected from at least one of graphite, hard carbon, silicon-based materials, and tin-based materials; when preparing a positive electrode sheet for a sodium-ion battery, the active material can be selected from at least one of sodium ion layered oxides (such as NaCoO2, NaMnO2), polyanionic compounds (such as Na3V2(PO4)3, NaFeSO4F), Prussian blue and its analogues; when preparing a negative electrode sheet for a sodium-ion battery, the active material can be selected from at least one of carbon-based materials (such as graphite, soft carbon, hard carbon, graphene), titanium-based materials (such as TiO2, Na2Ti3O7), organic polymers (such as polyimide), and organic small molecules (such as hydroquinone); when preparing a positive electrode sheet for a zinc-manganese battery, the active material can be at least one of manganese dioxide, manganese trioxide, and manganese tetraoxide.

[0062] In a specific example, the active material of the positive electrode plate includes at least one of manganese dioxide, manganese trioxide and manganese tetraoxide.

[0063] In a specific example, the active material of the negative electrode plate includes zinc metal or manganese metal.

[0064] In one specific example, the non-biodegradable binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene oxide, and a cellulose binder; polytetrafluoroethylene and cellulose binders are optional. When polytetrafluoroethylene and cellulose binders are used as non-biodegradable binders, the film-forming properties of the active layer are further improved, thereby improving the cycle life of the battery. Specifically, the mass ratio of polytetrafluoroethylene to cellulose binder is 18-50:1, for example, 18:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, etc.

[0065] In a specific example, the cellulose-based binder includes at least one of sodium carboxymethylcellulose, hydroxypropyl methylcellulose, microcrystalline cellulose and hydroxyethyl cellulose.

[0066] In one specific example, the conductive agent includes at least one of Super P-Li, activated carbon, carbon nanotubes, acetylene black, Ketjen black, and graphite; Super P-Li and activated carbon are optional. Specifically, the mass ratio of Super P-Li to activated carbon can be 1-10:2, for example, 1:2, 2:2, 3:2, 4:2, 5:2, 6:2, 7:2, 8:2, 9:2, 10:2, etc.

[0067] In a specific example, the average molecular weight of the polyhydroxyalkanoate is 100,000 to 3,000,000, for example, 100,000, 200,000, 500,000, 1,000,000, 1,500,000, 2,000,000, 2,500,000, 3,000,000, etc. The use of polyhydroxyalkanoates with the above molecular weights is beneficial in balancing compatibility with non-biodegradable binders and adhesion with the current collector and active material, thereby improving film-forming properties and increasing the loading amount of active material, thereby improving the cycle life of the battery.

[0068] In a specific example, the film forming includes at least one of roll film forming, extrusion film forming, hot pressing film forming and dry spray film forming.

[0069] In a specific example, the conditions for rolling film formation include: pressure 1T-4T; temperature 80℃-120℃; specifically, the pressure can be 1T, 1.5T, 2T, 2.5T, 3T, 3.5T, 4T, etc.; the temperature can be 80℃, 90℃, 100℃, 110℃, 120℃, etc.

[0070] In a specific example, the mass ratio of the active material to the conductive agent is (4-10): (1-6), for example, 4:1, 6:1, 8:1, 10:1, 4:2, 6:2, 8:2, 10:2, 4:3, 6:3, 8:3, 10:3, 4:4, 6:4, 8:4, 10:4, 4:5, 6:5, 8:5, 10:5, 4:6, 6:6, 8:6, 10:6, etc.

[0071] In a specific example, the mass ratio of the active substance to the composite binder is (3-15):1, for example, 3:1, 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, etc.

[0072] In a specific example, the thickness of the active layer is 100 μm-1000 μm, for example, 100 μm, 200 μm, 400 μm, 600 μm, 800 μm, 1000 μm, etc.

[0073] In a specific example, in the active layer, the mass proportion of the active material is 50%-90%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%.

[0074] In the present application, "fiberization treatment" refers to forming a fibrous structure of the binder and microcrystalline cellulose to achieve bonding and molding of the components. The present application does not particularly limit the process of the fiberization treatment, and it can adopt the conventional fiberization treatment process in the art, for example, placing the components in a high-speed mixing device, using high-speed rotating equipment parts to generate a strong shear force to fiberize the components, or driving the powder by a high-speed airflow to fiberize the components under the high shear force of the airflow. The first mixture and the composite binder are mixed and fiberized, which can be mixed in steps and distributed for fiberization, or mixed in one step and then fiberized in one step, or mixed in steps and then fiberized in one step.

[0075] In a specific example, the conditions of the fiberization treatment include: stirring at 4000-10000 rpm for 1-20 min. For example, the stirring speed can be 4000 rpm, 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, etc., and the stirring time can be 1 min, 5 min, 10 min, 15 min, 20 min, etc.

[0076] In a specific example, the current collector includes at least one of carbon cloth, carbon paper, stainless steel mesh, stainless steel foil, titanium mesh, titanium foil, and nickel foam.

[0077] The second aspect of the present application provides a pole piece prepared by the preparation method described in the first aspect.

[0078] A third aspect of the present application provides a pole piece, comprising a current collector and an active layer disposed on a surface of the current collector;

[0079] The active layer includes active material, conductive agent and composite binder;

[0080] The composite binder includes polyhydroxyalkanoate and non-biodegradable binder;

[0081] In the composite binder, the mass proportion of polyhydroxyalkanoate is 5%-80%.

[0082] In a specific example, in the composite binder, the mass proportion of polyhydroxyalkanoate can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0083] It can be understood that the use of the composite binder enables the active layer to be suitable for dry film formation and the corresponding electrode to be prepared.

[0084] In a specific example, the dry film forming includes at least one of roll film forming, extrusion film forming, hot pressing film forming and dry spray film forming.

[0085] The fourth aspect of the present application provides the use of the electrode described in the second or third aspect in a battery or an electrical device.

[0086] The fifth aspect of the present application provides a battery comprising the electrode described in the second or third aspect.

[0087] In a specific example, the battery includes at least one of a sodium ion battery, a potassium ion battery and a zinc-manganese battery; a zinc-manganese battery can be selected, and an aqueous zinc-manganese battery can be further selected.

[0088] In a specific example, a battery includes positive and negative electrode sheets, a separator and an electrolyte spaced between the positive and negative electrode sheets.

[0089] Among them, the positive and negative electrode sheets can be the electrode sheets described above.

[0090] In the present application, there is no particular limitation on the type of isolation membrane, and any known isolation membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0091] In a specific example, the material of the isolation membrane can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0092] The electrolyte conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0093] In a specific example, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0094] In a specific example, when the battery is a lithium ion battery, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorodioxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0095] In a specific example, when the battery is a lithium-ion battery, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0096] In a specific example, when the battery is a zinc-manganese battery, the electrolyte may be one or more of ammonium chloride, zinc chloride, potassium hydroxide, sodium hydroxide, zinc sulfate, and manganese sulfate, and the solvent may be water.

[0097] In a specific example, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly through a winding process or a lamination process.

[0098] In a specific example, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0099] In a specific example, the outer packaging of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery can also be a soft shell, such as a bag-type soft shell. The material of the soft shell can be plastic. Further, non-limiting examples of plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0100] The sixth aspect of the present application provides an electrical device comprising the electrode described in the second or third aspect, or the battery described in the fifth aspect.

[0101] In a specific example, the power-consuming device may be a mobile phone, a laptop computer, a smartwatch, an electric car, a medical device, a portable charging station, aerospace equipment, a smart home, or an energy storage power station. The energy storage power station may be a photovoltaic energy storage station, a wind power energy storage station, a hydropower energy storage station, a thermal power energy storage station, or the like.

[0102] Unless otherwise specified, the raw materials used in the following experiments can be purchased from the market.

[0103] Polyhydroxyalkanoate (PHA): average molecular weight 500,000, 1.5 million, and 2.66 million, provided by Guangdong Hefeng Biotechnology Co., Ltd.

[0104] PTFE: purchased from Daikin Corporation, Japan;

[0105] Cellulose: 15 μm microcrystalline cellulose, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0106] Polyvinylidene fluoride (PVDF): purchased from Arkema, France;

[0107] Polyethylene oxide: purchased from Sumitomo Corporation of Japan;

[0108] Carbon nanotubes: purchased from Jiangsu Tianxin Innovation Materials Technology Co., Ltd.

[0109] Acetylene black, Ketjen black, and super P Li were purchased from Lion (International) Co., Ltd., Japan;

[0110] Graphite: purchased from Shenzhen Suiheng Technology Co., Ltd.

[0111] Activated carbon: purchased from Toray Industries, Ltd., Japan;

[0112] Current collector: nickel mesh and stainless steel mesh, purchased from Hebei Chaoqun Waterproof Materials Co., Ltd.

[0113] The following are specific examples.

[0114] Example 1

[0115] Preparation method of positive electrode sheet:

[0116] 1) Preparing a first mixture: mixing the active material manganese dioxide, the conductive agent super P Li, and the conductive agent activated carbon in a mass ratio of 35:6:4 (i.e., the mass ratio of the active material to the conductive agent is 7:2, and the mass ratio of super P Li to the activated carbon is 3:2) to obtain a first mixture.

[0117] 2) Preparing a second mixture: adding PHA (average molecular weight 1.5 million) to the first mixture and stirring at 4000 rpm for 2 minutes to uniformly mix; then adding non-biodegradable binders (PTFE and cellulose) and stirring at 4000 rpm for 2 minutes, 6000 rpm for 2 minutes, and 7500 rpm for 5 minutes to uniformly mix and completely fiberize, to obtain a second mixture; wherein PHA, PTFE, and cellulose together constitute a composite binder, and the weight proportions of the three in the composite binder are 49%, 49%, and 2%, respectively; and the mass ratio of the active substance to the composite binder is 10:1;

[0118] 3) Preparation of active layer: The second mixture was placed in a roller press, the temperature of the roller press was controlled to 100°C, the thickness of the roller press was adjusted to 500 μm, and the active layer was obtained by roller pressing (pressure 2T; temperature 100°C).

[0119] 4) Preparation of positive electrode sheet: The formed active layer is composited onto the current collector (stainless steel mesh) by roller pressing, placed in a forced air oven, and dried at 120°C overnight to prepare the positive electrode sheet.

[0120] Example 2

[0121] The mass ratio of active material to conductive agent was 5:4, the mass ratio of active material to composite binder was 12:1, and the mass proportions of PHA (average molecular weight of 2.66 million), PTFE and cellulose in the composite binder were 19.6%, 78.4% and 2%, respectively; and the current collector used nickel mesh, the rest was the same as in Example 1.

[0122] Example 3

[0123] The same procedures as in Example 1 were employed except that the mass ratio of active material to conductive agent was 8:1, the mass ratio of active material to composite binder was 4:1, and the mass proportions of PHA, PTFE, and cellulose in the composite binder were 80% (average molecular weight of 500,000), 19%, and 1%, respectively.

[0124] Example 4

[0125] Except that the biodegradable binder is PTFE, the rest is the same as in Example 1.

[0126] Example 5

[0127] Except that the biodegradable binder is PVDF, the rest is the same as in Example 2.

[0128] Example 6

[0129] The same procedures as in Example 3 were followed except that PVDF (19%) and polyethylene oxide (1%) were used as the non-biodegradable binder.

[0130] Example 7

[0131] The same procedures as in Example 1 were followed except that the conductive agent used carbon nanotubes and acetylene black (mass ratio was 7:1) and the thickness of the active layer was 300 μm.

[0132] Example 8

[0133] The same procedures as in Example 2 were followed except that the conductive agent used graphite and Ketjen black (mass ratio was 7:1) and the thickness of the active layer was 100 μm.

[0134] Example 9

[0135] Preparation of negative electrode sheet:

[0136] Except for using zinc powder as the active material to prepare the negative electrode sheet, the rest is the same as Example 1.

[0137] Comparative Example 1

[0138] Except that the composite binder was replaced by PHA (ie, only PHA with an average molecular weight of 1.5 million was used as the binder), the rest was the same as in Example 4.

[0139] Comparative Example 2

[0140] Except that the composite binder is replaced by PTFE (ie, only PTFE is used as the binder), the rest is the same as Example 4.

[0141] Comparative Example 3

[0142] The same procedures as in Example 4 were followed except that PHA (average molecular weight 1.5 million) accounted for 90% of the composite adhesive.

[0143] Comparative Example 4

[0144] The same procedures as in Example 4 were followed except that PHA (average molecular weight 1.5 million) accounted for 95% of the composite adhesive.

[0145] Test Case

[0146] The positive electrode sheets of the embodiments and comparative examples were made into batteries. The preparation steps were as follows: the positive electrode sheets of the above embodiments 1-8 and comparative examples 1-4 were used as the positive electrode, the negative electrode sheet of embodiment 9 was used as the negative electrode, a glass fiber separator was used as the separator, and an aqueous solution of 2M ZnSO4, 0.5M MnSO4, 0.1M [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide), and 1% PEG-2000 was used as the electrolyte to assemble into an aqueous zinc-manganese battery.

[0147] The assembled batteries were tested for the following performances, and the results are shown in Table 1:

[0148] The cycle test uses the Xinwei battery test system, charging to 1.8V at a constant current of 0.1C, and then discharging to 1.0V, recording the battery's first-cycle discharge capacity Q1; then this is regarded as a cycle, and the cycle is repeated 100 times, recording the discharge capacity Q2 after 100 cycles; the capacity retention rate after 100 cycles is calculated by Q2 / Q1×100%, and the discharge capacity retention rate is calculated.

[0149] Table 1 Summary of performance of examples and comparative examples

[0150]

[0151] As can be seen from Table 1, the batteries of Examples 1-8 of the present application have good cycle life, among which Example 1-4 has the best effect. As can be seen from Examples 1-4 and Examples 5-8, the type of non-biodegradable binder and the type of conductive agent also have a certain impact on the cycle life of the battery.

[0152] Comparison of Example 4 and Comparative Examples 1-2 shows that using a composite of PHA and PTFE as a binder can significantly improve the first-cycle discharge capacity and cycle life of the battery compared to using PHA or PTFE alone as a binder.

[0153] Comparing Example 4 with Comparative Examples 3-4 shows that excessively high PHA content in the composite binder significantly degrades the battery's first-cycle discharge capacity and capacity retention after 100 cycles. This is because the added PTFE is insufficient to improve the PHA's film-forming properties and ensure film quality.

[0154] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing a pole piece, characterized in that: The steps include: mixing the active material and the conductive agent to form a first mixture; The first mixture and a composite binder are mixed and subjected to a fiberizing treatment to form a second mixture; the composite binder comprises polyhydroxyalkanoate and a non-biodegradable binder; forming the second mixture into a film to form an active layer; Compounding the active layer with the current collector to form the pole piece; In the composite binder, the mass proportion of polyhydroxyalkanoate is 5%-80%.

2. The preparation method according to claim 1, wherein One or more of the following conditions are met: (1) The electrode is a positive electrode or a negative electrode; (2) The non-biodegradable binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene oxide and cellulose binder; (3) The conductive agent includes at least one of Super-Li, activated carbon, carbon nanotubes, acetylene black, Ketjen black and graphite; (4) The average molecular weight of the polyhydroxyalkanoate is 100,000 to 3,000,000; (5) The film forming method includes at least one of roll film forming, extrusion film forming, hot pressing film forming and dry spray film forming.

3. The preparation method according to claim 2, wherein One or more of the following conditions are met: (1) The active material of the positive electrode plate includes at least one of manganese dioxide, manganese trioxide and manganese tetraoxide; (2) The active material of the negative electrode plate includes zinc metal or manganese metal; (3) The non-biodegradable binder includes at least one of polytetrafluoroethylene and a cellulose binder; (4) The cellulose binder includes at least one of sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, microcrystalline cellulose and hydroxyethyl cellulose; (5) The conditions for the roll-forming film include: pressure 1T-4T; Temperature 80℃-120℃.

4. The preparation method according to any one of claims 1 to 3, wherein The mass ratio of the active material to the conductive agent is (4-10): (1-6); The mass ratio of the active substance to the composite binder is (3-15):

1.

5. The preparation method according to claim 4, wherein The thickness of the active layer is 100 μm-1000 μm; In the active layer, the mass proportion of the active material is 50%-90%.

6. A pole piece prepared by the preparation method according to any one of claims 1 to 5.

7. A pole piece, characterized in that: It includes a current collector and an active layer arranged on the surface of the current collector; The active layer includes active material, conductive agent and composite binder; The composite binder includes polyhydroxyalkanoate and non-biodegradable binder; In the composite binder, the mass proportion of polyhydroxyalkanoate is 5%-80%.

8. Use of the electrode according to claim 6 or 7 in a battery or an electrical device.

9. A battery, characterized in that: Including the pole piece according to claim 6 or 7.

10. An electrical device, characterized in that: Including the pole piece according to claim 6 or 7 or the battery according to claim 9.

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