Active material thread, preparation method, and use

Abstract

Disclosed in the present disclosure are an active material thread, a preparation method, and a use. The active material thread is formed by an electrode active material, polyester, a conductive agent, and a binder, the active material thread is woven on a filamentous carrier using the textile technology to form an electrode, and because the active material thread has good mechanical properties, the electrode of such a structure has good conformality, so that material pulverization caused by a volume change of the electrode in the charging and discharging process is inhibited to a certain extent, and cracking of an electrode sheet is inhibited. Compared with a traditional electrode manufactured by direct coating, a mesh electrode can improve the stability of the electrode, and can also improve the conductivity of ions, thereby ensuring the lithium ion transmission rate in the electrochemical process.

Description

Active material thread, preparation method and application Technical Field

[0001] The present disclosure relates to the field of electrode material technology, and in particular to active material wires, preparation methods, and applications. Background Art

[0002] Lithium-ion batteries, due to their high specific energy, high operating voltage, long cycle life, no memory effect, low self-discharge, and zero pollution, have been widely used in portable electronic devices such as mobile phones, cameras, and laptops. They are also listed as a candidate power source for electric vehicles, aerospace, military, and large-scale energy storage equipment. With the development of lithium-ion batteries, the requirements for battery safety performance and cycle life are becoming increasingly stringent. Improving the cycle life and safety of lithium-ion batteries has always been a technical focus.

[0003] The existing technology for preparing lithium-ion battery electrodes is to apply a slurry to an electrode sheet, and then subject the electrode sheet to rolling, slitting, winding, liquid injection, and chemical formation, ultimately making a lithium-ion battery. The electrode sheet coating method generally involves mixing an active material, a conductive agent, an adhesive, and a solvent to form a slurry, which is then applied to a current collector, followed by drying and rolling to form an electrode. Electrodes produced by this method are prone to deformation due to volume expansion during the charge and discharge process, which can lead to cracking of the electrode sheet or pulverization of the active material, fragmentation of material particles, and the continuous formation of an SEI film, which greatly deteriorates the battery's cycle performance. This is a problem that urgently needs to be solved in the current field of lithium-ion battery applications.

[0004] CN111490228A, a lithium battery electrode, preparation method thereof, and lithium battery containing the electrode, addresses the aforementioned issues. The invention proposes using a lithium ion exchange polymer as a modifying layer to coat the electrochemically active layer of the electrode, thereby providing the electrode with improved conformal properties, thereby ensuring the lithium ion transfer rate during the electrochemical process and reducing the coating's impact on impedance. However, this technology still uses a coating method to coat the electrode with a repair layer, which is difficult to achieve a good conformal effect on the electrode.

[0005] In view of this, the present disclosure is proposed.

[0006] Summary of the Invention

[0007] The purpose of the present disclosure is to provide active material wires, preparation methods and applications. The application of active material wires in electrodes is beneficial to improving the shape retention of the electrodes and suppressing the problems of material pulverization and electrode cracking caused by volume changes of the electrodes during charging and discharging.

[0008] The present disclosure is achieved as follows:

[0009] In a first aspect, the present disclosure provides an active material thread comprising an electrode active material, a binder, a conductive agent, and polyester.

[0010] In some embodiments, the electrode active material includes a positive electrode active material or a negative electrode active material.

[0011] In some embodiments, the positive electrode active material includes at least one of lithium iron phosphate and nickel-cobalt-manganese ternary material.

[0012] In some embodiments, the negative electrode active material includes at least one of graphite and carbon fiber.

[0013] In some embodiments, the average particle size of the electrode active material is 0.5 μm-15 μm.

[0014] In some embodiments, the adhesive is polyvinylidene fluoride.

[0015] In some embodiments, the conductive agent is at least one of acetylene black and conductive carbon black.

[0016] In some embodiments, the polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate.

[0017] In some embodiments, the mass ratio of the electrode active material, the binder, the conductive agent and the polyester is (45-50):(3-4):(2-3):(46-52).

[0018] In some embodiments, the active material thread has a diameter of 20 μm to 30 μm.

[0019] In a second aspect, the present disclosure provides a method for preparing the active material wire as described in any one of the aforementioned embodiments, wherein a slurry obtained by mixing electrode active material, adhesive, conductive agent, polyester and solvent in proportion is subjected to spinning to obtain the active material wire.

[0020] In some embodiments, the ratio of the mass of the solvent to the total mass of the electrode active material, the binder, the conductive agent and the polyester in the slurry is 100:(20-30).

[0021] In some embodiments, the solvent is N-methylpyrrolidone.

[0022] In some embodiments, the filament making step includes discharging the slurry from small holes of a spinning box into a coagulation bath to form solid filaments, and then drying the filaments to obtain active material filaments.

[0023] In some embodiments, the oxygen content in the spinning box is less than the limiting oxygen content of the added slurry.

[0024] In some embodiments, the oxygen content in the spinning box is ≤16 vol%.

[0025] In some embodiments, the coagulation bath comprises sulfuric acid, sodium sulfate, and water.

[0026] In some embodiments, the concentration of sulfuric acid in the coagulation bath is 10 g / L-15 g / L, and the concentration of sodium sulfate in the coagulation bath is 20 g / L-25 g / L.

[0027] In some embodiments, the drying temperature is 110° C.-125° C., and the drying time is 3.5 h-4.5 h.

[0028] In some embodiments, the temperature of the slurry in the spinning box is 220°C-230°C.

[0029] In a third aspect, the present disclosure provides a battery pole piece prepared using textile technology, comprising a filamentous carrier frame and a pattern woven on the filamentous carrier frame using active material threads according to any one of the aforementioned embodiments.

[0030] In some embodiments, the diameter of the filamentous carrier is 18 μm-22 μm.

[0031] In some embodiments, the filamentous carrier is a copper wire or an aluminum wire.

[0032] In some embodiments, in the battery pole piece, the number of active material threads within 10 cm in the longitudinal direction is 4500-6000, and the number of active material threads within 10 cm in the latitudinal direction is 4500-6000.

[0033] In a fourth aspect, the present disclosure provides a method for preparing a battery pole piece using textile technology as described in any of the aforementioned embodiments, comprising building a filamentous carrier into a frame of a preset shape, and then using active material silk threads to weave a preset pattern on the filamentous carrier to obtain a battery pole piece.

[0034] In some embodiments, the active material threads are braided onto the filamentous carrier using a braiding machine.

[0035] In some embodiments, the knitting method is computerized flat knitting.

[0036] In a fifth aspect, the present disclosure provides a battery, comprising the battery electrode sheet described in any one of the aforementioned embodiments or the battery electrode sheet obtained by the method described in any one of the aforementioned embodiments.

[0037] In a sixth aspect, the present disclosure provides an electrical device comprising the battery described in the aforementioned embodiment.

[0038] The present disclosure has the following beneficial effects:

[0039] The electrode active material disclosed in the present invention, together with polyester, a conductive agent, and an adhesive, constitutes an active material thread. The active material thread is woven onto a filamentous carrier using textile technology to form an electrode. Since the active material thread has good mechanical properties (such as high tensile strength, high elasticity, and high elongation at break), the electrode structure has good conformal properties, thereby, to a certain extent, suppressing the material pulverization caused by the volume change of the electrode during the charge and discharge process, and can also play a role in suppressing the cracking of the electrode piece. Compared with the traditional electrode made by direct coating, this mesh electrode can improve the stability of the electrode, and can also improve the ionic conductivity, ensuring the lithium ion transmission rate during the electrochemical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0041] FIG1 is a cross-sectional view of the electrode produced in Example 1. DETAILED DESCRIPTION

[0042] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0043] The present disclosure provides an active material thread including an electrode active material, a binder, a conductive agent, and polyester.

[0044] Polyester is a general term for polymers obtained by the condensation of polyols and polyacids, and can be made into polyester fibers. The present invention utilizes the property of polyester that is easy to prepare fibers, combines electrode active materials with polyester, and prepares them into silk threads for use in electrodes. Compared with coating the electrode active materials on the electrode sheets, the electrode active materials are wrapped in polyester. The binding force of polyester can inhibit the volume expansion of the electrode active materials, while also protecting the electrode active materials and improving the cycle stability.

[0045] Since polyester has poor electrical conductivity, a conductive agent is introduced into the wire to ensure the electrical conductivity of the electrode.

[0046] Although polyester has good silk-forming properties, it has poor adhesion to the electrode active material. The electrode active material on the polyester surface is easy to fall off during use. Therefore, an adhesive is also introduced into the active material thread. The adhesive can improve the adhesion between the electrode active material and the adhesive. The adhesive and polyester are combined to make the adhesive and polyester stably wrapped on the surface of the electrode active material, preventing the electrode active material from being exposed on the thread surface and preventing the electrode active material from falling off.

[0047] In some embodiments, the electrode active material includes a positive electrode active material or a negative electrode active material, which can be selected according to needs. That is, if applied to the positive electrode, the electrode active material is selected as a positive electrode active material, and if applied to the negative electrode, the electrode active material is selected as a negative electrode active material.

[0048] In some embodiments, the positive electrode active material includes at least one of lithium iron phosphate and nickel-cobalt-manganese ternary material.

[0049] In some embodiments, the negative electrode active material includes at least one of graphite and carbon fiber.

[0050] In some embodiments, the average particle size of the electrode active material is 0.5 μm-15 μm, specifically 0.5 μm, 1 μm, 3 μm, 5 μm, 10 μm, 15 μm, or any value between 0.5 μm and 15 μm.

[0051] The electrode active material has poor deformability, and the silk thread will inevitably bend when it is woven into an electrode. If the particle size of the electrode active material is too large, the electrode active material will also be subjected to greater stress when the silk thread is bent, which may cause the electrode active material to crack or even break. At the same time, the electrode active material with poor deformability will separate from the polyester and adhesive in contact with it, causing the silk thread to affect the battery's cycle performance after being used in the battery.

[0052] In some embodiments, the adhesive is polyvinylidene fluoride.

[0053] In some embodiments, the conductive agent is at least one of acetylene black and conductive carbon black, which is more conducive to improving the conductive properties of the electrode active material wire.

[0054] In some embodiments, the polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate.

[0055] In some embodiments, the mass ratio of the electrode active material, binder, conductive agent, and polyester is (45-50):(3-4):(2-3):(46-52). Specifically, the electrode active material can be 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, or any value between 45-50; the binder can be 3 parts, 3.5 parts, 4 parts, or any value between 3-4; the conductive agent can be 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, or any value between 2-3; and the polyester can be 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, or any value between 46-52.

[0056] In order to prepare silk threads containing electrode active materials while ensuring the achieved strength, toughness and other properties, the polyester content must be reasonably selected. If the polyester content is too high, the relative content of electrode active materials will be reduced, reducing the battery energy density; if the polyester content is too low, it will not meet the needs of silk making, and the achieved strength, toughness, etc. will be reduced, and it will be easy to crack or even break.

[0057] Considering the introduction of polyester, a material with poor conductivity, into the yarn, the conductive agent content is higher than that required for electrode preparation using a coating method to ensure the yarn's conductivity. Furthermore, since the introduction of polyester significantly changes the slurry composition, the binder must not only adhere to the electrode active material but also strengthen the adhesion between the electrode active material, the polyester, and the conductive agent. Therefore, the binder content in this embodiment should not be too low.

[0058] In some embodiments, the diameter of the active material thread is 20 μm-30 μm, specifically 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, or any value between 20 μm and 30 μm.

[0059] If the diameter of the active material thread is too small, the thread is prone to cracking or even breaking; if the diameter of the active material thread is too large, the stress it is subjected to when it bends during the weaving process is greater, and the active material is more likely to separate from the contact points with polyester, adhesive and conductive agent at the bend, making the active material thread more likely to crack or even break.

[0060] The present disclosure provides a method for preparing the active material thread according to any one of the aforementioned embodiments, wherein a slurry obtained by mixing an electrode active material, a binder, a conductive agent, polyester and a solvent in proportion is subjected to silk making to obtain the active material thread.

[0061] In some embodiments, the ratio of the mass of the solvent to the total mass of the electrode active material, the binder, the conductive agent and the polyester in the slurry is 100:(20-30), specifically 100:20, 100:22, 100:24, 100:26, 100:28, 100:30 or any value between 100:(20-30).

[0062] In this application, since the adhesive and polyester have relatively high viscosity even in the molten state, the dispersion effect of the conductive agent and the electrode active material is poor. Therefore, a solvent is added to the slurry to allow the electrode active material and the conductive agent to be evenly dispersed in the conductive agent.

[0063] In this embodiment, the slurry contains a large amount of solvent. During the subsequent drying process of the silk thread, the solvent gradually evaporates, leaving holes, which are conducive to the migration of lithium ions.

[0064] In some embodiments, the solvent is N-methylpyrrolidone.

[0065] In some embodiments, the filament making step includes discharging the slurry from small holes of a spinning box into a coagulation bath to form solid filaments, and then drying the filaments to obtain active material filaments.

[0066] In some embodiments, the oxygen content in the spinning box is less than the limit oxygen content of the added slurry to avoid explosion.

[0067] In some embodiments, the oxygen content in the spinning box is ≤16 vol%, and other components may be inert gases such as nitrogen.

[0068] In some embodiments, the coagulation bath comprises sulfuric acid, sodium sulfate, and water.

[0069] In some embodiments, the concentration of sulfuric acid in the coagulation bath is 10 g / L-15 g / L, specifically 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L or any value between 10 g / L and 15 g / L; the concentration of sodium sulfate in the coagulation bath is 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, 25 g / L, specifically 20 g / L-25 g / L or any value between 20 g / L and 25 g / L.

[0070] In some embodiments, the drying temperature is 110°C-125°C, specifically 110°C, 115°C, 120°C, 125°C or any value between 110°C-125°C, and the drying time is 3.5h-4.5h, specifically 3.5h, 4h, 4.5h or any value between 3.5h-4.5h. This allows the solvent to be fully removed, and the rate of solvent evaporation can be adjusted by adjusting the temperature, thereby avoiding excessive drying that results in excessively large pores inside that affect battery performance. N-methylpyrrolidone has a boiling point above 200 degrees Celsius, so the drying speed at 110°C-125°C is relatively slow, and the gaps left by the slow evaporation of the solvent are smaller and more evenly distributed, which is more conducive to ion migration.

[0071] In some embodiments, the temperature of the slurry in the spinning box is 220°C-230°C, specifically 220°C, 230°C or any value between 220°C and 230°C.

[0072] The temperature of the slurry will affect the viscosity, fluidity, etc. of the slurry, which in turn will affect the achieved formability, strength, toughness, etc. The mechanical properties of the electrode material wire obtained under this temperature condition are better.

[0073] The present disclosure provides a battery pole piece prepared by using textile technology, comprising a filamentous carrier frame and a pattern woven on the filamentous carrier frame using active material threads according to any one of the aforementioned embodiments.

[0074] In this embodiment, the battery pole pieces are woven on a filamentary carrier frame, and gaps are inevitably left between the active material threads. Even if the volume of the electrode active material expands slightly, it will not affect the adjacent threads, and even if such volume expansion occurs, it will not accumulate like the electrodes prepared by the coating method. At the same time, since the filamentary carrier frame and the active material threads are not bonded and fixed, the filamentary carrier frame and the active material threads can move relative to each other within a certain range. The volume expansion of the electrode active material at some positions will not compress the active material threads at other positions, or even if the active material threads are compressed, they can slowly move under the action of pressure, so that the forces on the active material threads and the filamentary carrier frame are relatively balanced, which is beneficial to improving the stability of the electrode.

[0075] In some embodiments, the diameter of the filamentous carrier is 18 μm-22 μm, which plays a stable supporting role. Specifically, it can be 18 μm, 19 μm, 20 μm, 21 μm, 22 μm or any value between 18 μm and 22 μm.

[0076] In some embodiments, the filamentous carrier is a copper wire or an aluminum wire.

[0077] In some embodiments, in the battery electrode, the number of active material threads within 10 cm in the longitudinal direction is 4500-6000, specifically 4500, 5000, 5500, 6000 or any value between 4500-6000, and the number of active material threads within 10 cm in the latitudinal direction is 4500-6000, specifically 4500, 5000, 5500, 6000 or any value between 4500-6000.

[0078] Active materials can only have a certain strength when they reach a certain density. However, if the density is too high, the active material threads will squeeze each other. The different deformability of the electrode active material and polyester will also make it easy for the electrode active material to separate from the contact point with the thread, causing the active material thread to crack or even break.

[0079] The present disclosure provides a method for preparing a battery pole piece using textile technology as described in any of the aforementioned embodiments, comprising: building a filamentous carrier into a frame of a preset shape, and then using active material silk threads to weave a preset pattern on the filamentous carrier to obtain a battery pole piece.

[0080] The specific shapes of the frame and pattern can be selected by those skilled in the art as needed.

[0081] In some embodiments, a braiding machine is used to weave the active material threads onto the filamentous carrier. Machine weaving is conducive to mass production and thus to industrial applications. The specific braiding machine model can be selected by technicians in the field according to the existing technology as needed. It mainly affects the efficiency and has little effect on product performance under the same parameter settings.

[0082] In some embodiments, the knitting method is computerized flat knitting.

[0083] The present disclosure provides a battery, comprising the battery pole piece described in any one of the aforementioned embodiments or the battery pole piece obtained by the method described in any one of the aforementioned embodiments.

[0084] The present disclosure provides an electrical device, comprising the battery described in the aforementioned embodiment.

[0085] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0086] Example 1

[0087] A method for preparing a battery electrode in combination with textile technology, comprising:

[0088] (1) Mixing of raw materials:

[0089] Lithium iron phosphate positive electrode material, PVDF binder, conductive carbon black and polyethylene terephthalate are mixed together in a ratio of 45:3:2:52, and N-methylpyrrolidone (NMP) is used as a solvent. The mixture is stirred evenly to form a slurry. The average particle size of the lithium iron phosphate positive electrode material is 0.8 μm, and the ratio of the solvent mass to the total mass of the slurry is 100:120.

[0090] (2) Slurry silk making:

[0091] The slurry prepared in (1) is subjected to silk making by solution spinning technology.

[0092] S1: nitrogen is introduced into the spinning beam to make the oxygen content in the spinning beam 16 vol%;

[0093] The specific operation of S2 is to spit the slurry from a tiny hole in a spinning box at 220°C into a coagulation bath, and the slurry precipitates into solid filaments. The coagulation bath includes sulfuric acid, sodium sulfate and water, wherein the concentration of sulfuric acid is 10g / L, and the concentration of sodium sulfate is 20g / L. After drying at 110°C for 3.5h, the required slurry filaments can be obtained; the diameter of the filaments produced in this step is 20μm.

[0094] (3) Braided electrodes:

[0095] S1 uses aluminum wire with a diameter of about 20μm as a carrier and builds the aluminum wire into a circular skeleton according to the shape of the electrode required for the cylindrical battery;

[0096] S2 uses a complete set of garment knitting machines - a fully automatic 2-52 12G dual-system computer flat knitting machine. The pattern for weaving a circular electrode is set on the computer program. Starting from one of the aluminum wires, the filamentous slurry is mesh-woven on the carrier to obtain the circular electrode shown in Figure 1. In this electrode, the number of active material threads within 10 cm in the longitudinal direction is 4500, and the number of active material threads within 10 cm in the latitudinal direction is 6000.

[0097] Example 2:

[0098] A method for preparing a battery electrode in combination with textile technology, comprising:

[0099] (1) Mixing of raw materials:

[0100] The lithium iron phosphate positive electrode material, PVDF binder, conductive carbon black and polyethylene terephthalate are mixed together in a ratio of 50:4:2:46, and N-methylpyrrolidone (NMP) is used as a solvent. The mixture is stirred evenly to prepare a slurry. The average particle size of the lithium iron phosphate positive electrode material is 1.3 μm, and the ratio of the solvent mass to the total mass of the slurry is 100:130;

[0101] (2) Slurry silk making:

[0102] The slurry prepared in (1) is subjected to silk making by solution spinning technology.

[0103] S1: non-combustible gas is introduced into the spinning beam. In this embodiment, the oxygen content in the spinning beam is set to 14 vol%.

[0104] The specific operation of S2 is to spit the slurry from a tiny hole in a spinning box at 230°C into a coagulation bath, and the slurry precipitates into solid filaments. The coagulation bath includes sulfuric acid, sodium sulfate and water, wherein the concentration of sulfuric acid is 15g / L, and the concentration of sodium sulfate is 25g / L. After drying at 125°C for 4 hours, the required slurry filaments can be obtained; the diameter of the filaments produced in this step is 30μm.

[0105] (3) Braided electrodes:

[0106] S1 uses aluminum wire with a diameter of about 20μm as a carrier and builds the aluminum wire into a circular skeleton according to the shape of the electrode required for the cylindrical battery;

[0107] S2 uses a complete set of garment knitting machines - a fully automatic 2-52 12G dual-system computer flat knitting machine. The pattern for weaving a circular electrode is set on the computer program. Starting from one of the aluminum wires, the filamentous slurry is mesh-woven on the carrier to obtain the circular electrode shown in Figure 1. In this electrode, the number of active material threads within 10 cm in the longitudinal direction is 6000, and the number of active material threads within 10 cm in the latitudinal direction is 4500.

[0108] Example 3

[0109] This embodiment provides a method for preparing battery pole pieces by combining textile technology. The only difference from Example 1 is that the adhesive content is lower: lithium iron phosphate positive electrode material, PVDF binder, conductive carbon black and polyethylene terephthalate are mixed together in a ratio of 45:2:2:52.

[0110] Example 4

[0111] This embodiment provides a method for preparing battery pole pieces in combination with textile technology. The only difference from Example 1 is that the adhesive content is higher: lithium iron phosphate positive electrode material, PVDF binder, conductive carbon black and polyethylene terephthalate are mixed together in a ratio of 45:4:2:52.

[0112] Example 5

[0113] This embodiment provides a method for preparing battery pole pieces by combining textile technology. The only difference from Example 1 is that the polyethylene terephthalate content is lower: lithium iron phosphate positive electrode material, PVDF binder, conductive carbon black and polyethylene terephthalate are mixed together in a ratio of 45:3:2:44.

[0114] Example 6

[0115] This embodiment provides a method for preparing battery pole pieces by combining textile technology. The only difference from Example 1 is that the polyethylene terephthalate content is higher: lithium iron phosphate positive electrode material, PVDF binder, conductive carbon black and polyethylene terephthalate are mixed together in a ratio of 45:3:2:55.

[0116] Example 7

[0117] This embodiment provides a method for preparing battery electrodes in combination with textile technology. The only difference from Example 1 is that the electrode active material adopts a ternary positive electrode material (nickel, cobalt and manganese ratio of 8:1:1): the average particle size of the ternary positive electrode material is 10um.

[0118] Example 8

[0119] This embodiment provides a method for preparing a battery electrode in combination with textile technology. The only difference from Example 1 is that the diameter of the active material thread is larger: the diameter of the active material thread is 40 um.

[0120] Example 9

[0121] This embodiment provides a method for preparing battery electrodes in combination with textile technology. The only difference from Example 1 is the drying temperature and time: the desired slurry filaments can be obtained after drying at 100°C for 5 hours.

[0122] Example 10

[0123] This embodiment provides a method for preparing battery pole pieces in combination with textile technology. The only difference from Example 1 is the drying temperature and time: the desired slurry filaments can be obtained after drying at 130°C for 3 hours.

[0124] Example 11

[0125] This embodiment provides a method for preparing a battery electrode in combination with textile technology. The only difference from Example 1 is that the active material threads are denser: in the battery electrode, the number of active material threads within 10 cm in the longitude direction is 6000, and the number of active material threads within 10 cm in the latitude direction is 6000.

[0126] Example 12

[0127] This embodiment provides a method for preparing battery pole pieces by combining textile technology. The only difference from Example 1 is that the diameter of the filamentous carrier is 25 μm.

[0128] Comparative Example 1

[0129] Compared with Example 1, the comparative example adopts a coating method to prepare the electrode, specifically including:

[0130] (1) Mixing of raw materials:

[0131] The lithium iron phosphate positive electrode material, PVDF, conductive carbon black, and N-methylpyrrolidone were mixed together in a mass ratio of 50:4:46:500, stirred and dispersed thoroughly, and prepared into a slurry;

[0132] (2) Electrode coating:

[0133] The slurry was intermittently and evenly coated on both sides of the aluminum foil current collector, with a single-side coating thickness of 30 μm, and then the current collector was dried at 80°C for 8 hours to prepare a positive electrode sheet;

[0134] (3) Pole piece rolling:

[0135] The roller pressing is carried out by cold pressing, with a cold pressing speed of 10m / min, a cold pressing pressure of 50MP, and a cold pressing gap of 60μm;

[0136] (4) Prepare the positive electrode of lithium battery.

[0137] Comparative Example 2

[0138] This comparative example provides a method for preparing battery pole pieces by combining textile technology. The only difference from Example 1 is that the electrode weaving step is different: an aluminum sheet is selected as a carrier, and PVDF is used to bond the woven circular electrode pattern to the aluminum sheet.

[0139] Batteries were assembled using the electrodes prepared in the examples and comparative examples. Specifically, the positive electrode, separator, and negative electrode were stacked layer by layer, and electrolyte was filled between the positive and negative electrodes to form a battery. The cycle performance of the battery was tested at 25°C (1C / 1C 2.0-4.3V). The results are shown below: Industrial Applicability

[0140] The electrode active material disclosed in the present invention, together with polyester, a conductive agent, and an adhesive, constitutes an active material thread. The active material thread is woven onto a filamentous carrier using textile technology to form an electrode. Since the active material thread has good mechanical properties (such as high tensile strength, high elasticity, and high elongation at break), the electrode structure has good conformal properties, thereby, to a certain extent, suppressing the material pulverization caused by the volume change of the electrode during the charge and discharge process, and can also play a role in suppressing the cracking of the electrode piece. Compared with the traditional electrode made by direct coating, this mesh electrode can improve the stability of the electrode, and can also improve the ionic conductivity, ensuring the lithium ion transmission rate during the electrochemical process.

Claims

1. An active material thread, characterized in that: It includes electrode active material, adhesive, conductive agent and polyester.

2. The active material thread according to claim 1, characterized in that The electrode active material includes a positive electrode active material or a negative electrode active material.

3. The active material thread according to claim 2, characterized in that The positive electrode active material includes at least one of lithium iron phosphate and nickel-cobalt-manganese ternary material.

4. The active material thread according to claim 2 or 3, characterized in that: The negative electrode active material includes at least one of graphite and carbon fiber.

5. The active material thread according to any one of claims 1 to 4, characterized in that: The average particle size of the electrode active material is 0.5 μm-15 μm.

6. The active material thread according to any one of claims 1 to 4, characterized in that: The adhesive is polyvinylidene fluoride.

7. The active material thread according to any one of claims 1 to 4, characterized in that: The conductive agent is at least one of acetylene black and conductive carbon black.

8. The active material thread according to any one of claims 1 to 4, characterized in that: The polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate.

9. The active material thread according to any one of claims 1 to 4, characterized in that: The mass ratio of the electrode active material, the binder, the conductive agent and the polyester is (45-50):(3-4):(2-3):(46-52).

10. The active material thread according to any one of claims 1 to 4, characterized in that: The diameter of the active material wire is 20 μm-30 μm.

11. A method for preparing active material threads according to any one of claims 1 to 10, characterized in that: The electrode active material, the adhesive, the conductive agent, the polyester and the solvent are mixed in proportion to obtain the slurry, and the slurry is subjected to silk making to obtain the active material silk thread.

12. The method for preparing active material threads according to claim 11, characterized in that: The ratio of the mass of the solvent to the total mass of the electrode active material, the adhesive, the conductive agent and the polyester in the slurry is 100:(20-30).

13. The method for preparing active material threads according to claim 11 or 12, characterized in that: The solvent is N-methylpyrrolidone.

14. The method for preparing active material threads according to any one of claims 11 to 13, characterized in that: The filament making step includes discharging the slurry from the small holes of the spinning box into a coagulation bath to form solid filaments, and then drying the filaments to obtain active material filaments.

15. The method for preparing active material wire according to claim 14, characterized in that: The oxygen content in the spinning box is less than the limiting oxygen content of the added slurry.

16. The method for preparing active material threads according to claim 15, characterized in that: The oxygen content in the spinning box is ≤16 vol%.

17. The method for preparing active material thread according to any one of claims 14 to 16, characterized in that: The coagulation bath includes sulfuric acid, sodium sulfate and water.

18. The method for preparing active material threads according to claim 17, characterized in that: The concentration of sulfuric acid in the coagulation bath is 10 g / L-15 g / L, and the concentration of sodium sulfate in the coagulation bath is 20 g / L-25 g / L.

19. The method for preparing active material thread according to any one of claims 14 to 18, characterized in that: The drying temperature is 110℃-125℃, and the drying time is 3.5h-4.5h.

20. The method for preparing active material threads according to any one of claims 14 to 19, characterized in that: The temperature of the slurry in the spinning box is 220°C-230°C.

21. A battery pole piece prepared using textile technology, characterized in that: The invention comprises a filamentous carrier frame and a pattern in which the active material threads according to any one of claims 1 to 9 are woven on the filamentous carrier frame.

22. The battery pole piece prepared by textile technology according to claim 21, characterized in that: The diameter of the filamentous carrier is 18 μm-22 μm.

23. The battery pole piece prepared by textile technology according to claim 21 or 22, characterized in that: The filamentous carrier is a copper wire or an aluminum wire.

24. The battery pole piece prepared by textile technology according to any one of claims 21 to 23, characterized in that: In the battery pole piece, the number of active material threads within 10 cm in the longitude direction is 4500-6000, and the number of active material threads within 10 cm in the latitude direction is 4500-6000.

25. A method for preparing a battery electrode according to any one of claims 21 to 24, characterized in that: The method comprises building a filamentous carrier into a frame of a preset shape, and then using active material threads to weave a preset pattern on the filamentous carrier to obtain a battery pole piece.

26. The method for producing a battery pole piece according to claim 25, characterized in that: The active material threads are braided on the filamentous carrier by using a braiding machine.

27. The method for producing a battery pole piece according to claim 26, characterized in that: The knitting method is computerized flat knitting machine knitting.

28. A battery, characterized in that: Including the battery pole piece described in any one of claims 21-24 or the battery pole piece obtained by the method described in any one of claims 25-27.

29. An electrical equipment, characterized in that: Comprising the battery of claim 28.

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