Electrode sheet and method for manufacturing electrode sheet

Abstract

The invention provides an electrode sheet and a manufacturing method of the electrode sheet. Tensile strength is maintained and resistance is reduced in an electrode sheet. This method for manufacturing an electrode sheet is provided with: a step for preparing first cover active material particles by mixing at least a binder with a plurality of first active material particles; a step for preparing second covering active material particles by mixing at least a conductive auxiliary agent with the plurality of second active material particles; a step in which the first covering active material particles and the second covering active material particles are mixed to produce an electrode composite material mixture; and a step for forming the electrode composite material mixture in the form of a sheet.

Description

TECHNICAL FIELD

[0001] The technology disclosed in this specification relates to an electrode sheet and a manufacturing method of an electrode sheet. BACKGROUND

[0002] An electrode sheet and a manufacturing method of an electrode sheet are described in Patent Literature 1. The electrode sheet includes active material particles and a binder. The manufacturing method of the electrode sheet includes a step of preparing an electrode composite mixture by mixing the active material particles and the binder, and a step of preparing the electrode sheet from the electrode composite mixture.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2021-504877 SUMMARY

[0006] By adding a conductive aid to the electrode sheet as described above, the conductivity of the electrode sheet can be improved. The conductive aid is, for example, carbon black, a carbon nanotube, and forms a conductive path extending between the active material particles. However, when the conductive aid and the binder are mixed together into the active material particles, there is a possibility that the conductive aid is taken into the binder. In this case, the conductive aid extending between the active material particles decreases, and thus the conductivity of the electrode sheet cannot be sufficiently improved.

[0007] To avoid the above problem, it is considered to reduce the mixing amount of the binder. However, when the mixing amount of the binder is reduced, there is a possibility that the tensile strength of the electrode sheet decreases. Therefore, to improve the tensile strength of the electrode sheet, for example, it is considered to use a binder such as polytetrafluoroethylene (PTFE) that can be fibrillated. However, when the binder is fibrillated, the conductive aid is easily entangled with the binder. As a result, more conductive aid is taken into the binder, and the conductive aid extending between the active material particles further decreases.

[0008] In view of the above, the present specification provides a technology for maintaining the tensile strength and improving the conductivity in an electrode sheet.

[0009] The technology disclosed in this specification is embodied as a manufacturing method of an electrode sheet. In a first mode thereof, the manufacturing method of the electrode sheet includes a step of preparing a first active material particle-covered active material particle by mixing at least a binder to a plurality of first active material particles, a step of preparing a second active material particle-covered active material particle by mixing at least a conductive aid to a plurality of second active material particles, a step of preparing an electrode composite mixture by mixing the first active material particle-covered active material particle and the second active material particle-covered active material particle, and a step of forming the electrode composite mixture in a sheet shape.

[0010] The aforementioned manufacturing method includes a step of producing first covering active material particles and a step of producing second covering active material particles. Furthermore, an electrode composite material mixture is produced by mixing the first and second covering active material particles. In the step of producing the first covering active material particles, the mixing of the first active material particles and the binder can be carried out without considering the influence on the conductive additive. On the other hand, in the step of producing the second covering active material particles, the conductive additive can adhere to the second active material particles without being affected by the binder. Therefore, in the step of producing the electrode composite material mixture, when the first and second covering active material particles are mixed, the conductive additive is prevented from being absorbed into the binder. Thus, without reducing the amount of binder mixed, a relatively large amount of conductive additive can extend between the active material particles to form conductive paths, thereby enabling the manufacture of an electrode sheet with excellent tensile strength and conductivity.

[0011] The second method, as described in the first method, may also include a step of fabricating the first coating active material particles by applying at least a shear force to the adhesive to fibrillate the adhesive. This structure further enhances the tensile strength of the electrode sheet.

[0012] In the third method, as described in the first or second method, the shear force applied to the adhesive during the process of fibrillating the adhesive is at least greater than the shear force applied to the plurality of second active material particles and the conductive additive during the process of producing the second covering active material particles. According to this structure, the adhesion between the first covering active material particles and the adhesive can be improved.

[0013] In the fourth method, in any of the first to third methods, the conductive additive may also include at least one selected from the group consisting of carbon nanotubes and acetylene black. The carbon nanotubes have a tubular shape, and the acetylene black has a chain-like structure. When using a conductive additive with such a shape or structure, the conductive additives are easily entangled with each other, facilitating the formation of conductive paths. On the other hand, when the conductive additive has a tubular shape or a chain-like structure, it is easy for the conductive additive to be incorporated into the adhesive. However, in this technology, during the process of producing the second covering active material particles, the conductive additive is pre-attached to the second active material particles, thus effectively preventing the conductive additive from being incorporated into the adhesive.

[0014] In the fifth method, any of the methods from the first to the fourth, the electrode sheet can also be a freestanding electrode sheet. This structure can improve the energy density of the electrode. Furthermore, a freestanding electrode sheet refers to an electrode sheet that is self-supporting and does not require a support (e.g., a current collector).

[0015] The technology disclosed in this specification is further embodied in an electrode sheet. This electrode sheet can be manufactured using the manufacturing method described above. For example, in the sixth embodiment, the electrode sheet comprises a plurality of active material particles, a binder, and a conductive additive. The plurality of active material particles include a plurality of first active material particles whose surface is covered by the binder, and a plurality of second active material particles whose surface is covered by the conductive additive. As described above, the electrode sheet manufactured using this technology possesses excellent tensile strength and conductivity.

[0016] In the seventh method, as described in the sixth method, the adhesive can also be a fibrillated resin. This structure further improves the tensile strength of the electrode sheet.

[0017] In the eighth embodiment, as described in the sixth or seventh embodiment, the conductive additive may also include at least one selected from the group consisting of carbon nanotubes and acetylene black. According to this structure, the conductivity of the electrode sheet is improved by the conductive additive having a tubular or chain-like structure.

[0018] In the ninth method, any of the methods from the sixth to the eighth, the electrode sheet can also be a freestanding electrode sheet. This structure improves the energy density of the electrode. Attached Figure Description

[0019] Figure 1 This is a diagram that schematically shows the structure of the electrode body 100 employing the electrode sheet 10.

[0020] Figure 2 This is a diagram that roughly shows the structure of the electrode sheet 10.

[0021] Figure 3 This is a flowchart illustrating the manufacturing method of electrode sheet 10.

[0022] Figure 4 This diagram illustrates the process of producing first coated active material particles by mixing PTFE into a mixture of NCM single crystals and NCM polycrystals (NCM-1) using a mixer 104.

[0023] Figure 5 This diagram illustrates the process of fibrillating PTFE by applying shear force to PTFE using a kneader 110.

[0024] Figure 6 This diagram illustrates the process of using a pressing device 116 to form an electrode composite material mixture into a sheet shape.

[0025] Figure 7A This is a flowchart illustrating the manufacturing method of the electrode sheet 10 in Example 1.

[0026] Figure 7B This is a flowchart illustrating the manufacturing method of the electrode sheet in Comparative Example 1.

[0027] Figure 7C This is a flowchart illustrating the manufacturing method of the electrode sheet in Comparative Example 2.

[0028] Figure 8A The results of tensile strength determination are shown for Example 1 and Comparative Examples 1 and 2.

[0029] Figure 8B The resistance measurement results are shown for Example 1 and Comparative Examples 1 and 2. Detailed Implementation

[0030] Referring to the accompanying drawings, the electrode sheet 10 of this embodiment will be described. The electrode sheet 10 of this embodiment is used in the electrode body 100. The electrode body 100 is used, for example, as the positive electrode of a lithium-ion secondary battery.

[0031] like Figure 1 As shown, the electrode body 100 includes an electrode sheet 10 and a current collector 102. The current collector 102 is a conductive sheet. The current collector 102 is, for example, an aluminum foil or a copper foil. The thickness of the current collector 102 is, for example, 5 μm or more and 50 μm or less. The electrode sheet 10 is disposed on the current collector 102. The electrode sheet 10 is a freestanding electrode sheet. A freestanding electrode sheet, as referred to here, means an electrode sheet that is self-supporting without the need for a support such as the current collector 102. Therefore, the electrode body 100 does not necessarily need to include a current collector 102. That is, as another embodiment, the electrode sheet 10 may also constitute the electrode body 100 independently. The thickness of the electrode sheet 10 is, for example, 10 μm or more and 500 μm or less.

[0032] like Figure 2 As shown, the electrode sheet 10 includes a plurality of active material particles 12, 14, an adhesive 16, and a conductive additive 18. The plurality of active material particles 12, 14 include a plurality of first active material particles 12 and a plurality of second active material particles 14. At least a portion of the surface of each first active material particle 12 is covered by the adhesive 16. At least a portion of the surface of each second active material particle 14 is covered by the conductive additive 18.

[0033] As described above, the electrode sheet 10 of this embodiment is used as the positive electrode of a lithium-ion secondary battery, so each active material particle 12, 14 is a positive electrode active material particle. Examples of active material particles 12, 14 include, for example, lithium composite oxides. Examples of lithium composite oxides include, for example, lithium-nickel composite oxides, lithium-cobalt composite oxides, lithium-manganese composite oxides, and lithium-nickel-manganese composite oxides (e.g., LiNi). 1 / 2 Mn 3 / 2 O4), lithium nickel manganese cobalt composite oxides (e.g., LiNi)1 / 3Mn 1 / 3 Co 1 / 3 O2), etc. Each active substance particle 12, 14 can be composed of a single type of material or multiple types of materials. In addition, the compound used as the first active substance particle 12 can be the same as or different from the compound used as the second active substance particle 14.

[0034] The adhesive 16 binds the active material particles 12 and 14 together. Examples of adhesives 16 include carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), acrylic resin, and ultra-high molecular weight polyethylene. The adhesive 16 can be composed of a single type of material or multiple types of materials. In this embodiment, the adhesive 16 is a fibrillable resin, which is fibrillated in the electrode sheet 10. Furthermore, the term "fibrillable resin" as used herein refers to a resin that can be fibrillated by applying shear force. Examples of fibrillable resins include cellulose, acrylic resin, ultra-high molecular weight polyethylene, and PTFE.

[0035] The conductive additive 18 can form conductive paths extending between the active material particles 12 and 14 within the electrode sheet 10. Examples of conductive additives 18 include carbon nanotubes, carbon black (e.g., acetylene black, furnace black, Ketjen black, etc.), coke, and graphite. The conductive additive 18 can be composed of a single type of material or multiple types of materials.

[0036] Next, refer to Figures 3-6 This describes a method for manufacturing the electrode sheet 10. In this method, the electrode sheet 10 can be manufactured without the use of solvents. That is, this manufacturing method is a so-called dry process.

[0037] like Figure 3 As shown, the manufacturing method includes a step (S10) of mixing adhesive 16 into a plurality of first active material particles 12 to form first covered active material particles. In this step, as... Figure 4As shown, for example, a mixer 104 is used. The mixer 104 mixes the first active material particles 12 and the adhesive 16, which are fed into the container 108, by rotating the blade 106. This creates a first covering active material particle to which the adhesive 16 is attached to the first active material particles 12. That is, in the first covering active material particle, at least a portion of the surface of the first active material particle 12 is covered by the adhesive 16. In this process, other necessary materials may also be mixed in addition to the first active material particles 12 and the adhesive 16. However, the conductive additive 18 is not mixed in this process. Since the conductive additive 18 is absent, there is no need to consider its effect on the conductive additive 18, and the mixing of the first active material particles 12 and the adhesive 16 can be carried out.

[0038] In this embodiment, the mixer 104 increases the rotational speed of the blade 106 in stages, mixing the first active material particles 12 and the binder 16 through two different rotational speeds. However, the mixer 104 need not necessarily increase the rotational speed of the blade 106 in two stages. In other embodiments, the rotational speed of the blade 106 can be constant or increased in three or more stages. Furthermore, in S10, the mixer 104 is not necessarily required. In other embodiments, other mixers such as blenders or grinders can be used instead of the mixer 104.

[0039] like Figure 3 As shown, the manufacturing method further includes a step (S12) of fibrillating the adhesive 16 by applying shear force to the first covering active material particles. In this step, as... Figure 5 As shown, for example, a kneader 110 is used. The kneader 110 applies shear force to the first covering active material particles present between the blade 112 and the wall 114a of the container 114 by rotating the blade 112. As described above, the adhesive 16 in this embodiment is a fibrillable resin, so by applying shear force to the adhesive 16 constituting the first covering active material particles, the adhesive 16 is fibrillated. As a result, the tensile strength of the electrode sheet 10 can be further improved. In addition, it is not necessary to use the kneader 110 in S12. In other embodiments, other mixers such as mixers and grinders may be used instead of the kneader 110. Furthermore, although not particularly limited, the processing in S12 may also be performed while the container 114 of the kneader is heated at a predetermined temperature.

[0040] like Figure 3 As shown, the manufacturing method further includes a step (S14) of producing a second coated active material particle by mixing a conductive additive 18 into the second active material particle 14. In this step, as... Figure 4As shown, for example, a mixer is used. The mixer mixes the second active material particles 14 and the conductive additive 18, which are added to the container, by rotating the blades. This creates a second covering active material particle to which the conductive additive 18 adheres to the second active material particles 14. That is, in the second covering active material particle, at least a portion of the surface of the second active material particle 14 is covered by the conductive additive 18. In this process, other necessary materials may also be mixed in addition to the second active material particles 14 and the conductive additive 18. As an example, in this embodiment, PVdF is mixed in. PVdF is an additive used to bind the second active material particles 14 and the conductive additive 18 together in the mixing of the second active material particles 14 and the conductive additive 18. That is, the PVdF used in this process is not intended to bind the active material particles 12 and 14 together in the electrode sheet 10, as the adhesive 16 used in S10. Therefore, the amount of PVdF mixed is relatively small, and the conductive additive 18 is not incorporated into the PVdF. Materials other than PVdF can be used as such additives, but resins that can be fibrillated, such as PTFE, should be avoided.

[0041] like Figure 3 As shown, the manufacturing method further includes a step (S16) of mixing first covering active material particles and second covering active material particles to prepare an electrode composite material mixture. In this step, as... Figure 4 As shown, for example, a mixer is used. By rotating the blades of the mixer, the first and second covering active material particles, which are introduced into the container, are mixed. This produces an electrode composite material mixture. In producing the electrode composite material mixture in this way, for example, compared to producing the electrode composite material mixture by mixing each of the active material particles 12, 14, the binder 16, and the conductive additive 18 at once, the conductive additive 18 is inhibited from being incorporated into the binder 16.

[0042] like Figure 3 As shown, the manufacturing method further includes a step (S18) of forming the electrode composite material mixture into a sheet shape. In this step, as... Figure 6 As shown, for example, a pressing device 116 is used. The pressing device 116 includes a pair of rollers 118 configured to roll an electrode composite material mixture passing between the pair of rollers 118. Therefore, the electrode composite material mixture is formed into a sheet shape by rolling it with the pair of rollers 118. Thus, an electrode sheet 10 is produced. As described above, the produced electrode sheet 10 is a freestanding electrode sheet. Furthermore, although not particularly limited, the processing in S18 can also be performed while the pair of rollers 118 are heated at a predetermined temperature.

[0043] According to the above manufacturing method, without reducing the amount of binder 16 mixed, a relatively large amount of conductive additive 18 can be extended between active material particles 12 and 14 to form a conductive path, so it is possible to manufacture an electrode sheet 10 with excellent tensile strength and conductivity.

[0044] The average particle size of each active material particle 12, 14 used to fabricate the electrode sheet 10 is, for example, 1 μm or more and 25 μm or less, and for example, 1.5 μm or more and 20 μm or less. Furthermore, the average particle size referred to herein means the particle size (D50) at the cumulative 50% of the particle size distribution on a volume basis determined by laser diffraction / scattering. There is no particular limitation on the relationship between the average particle size of the first active material particle 12 and the average particle size of the second active material particle 14. Additionally, each active material particle 12, 14 can be a single type of positive electrode active material particle having any average particle size, or multiple types of positive electrode active material particles with different average particle sizes can be used in combination.

[0045] The content of the first active material particles 12 and the second active material particles 14 in the electrode composite material mixture is, for example, 90% by weight or more and 99% by weight or less, and for example, 95% by weight or more and 98.5% by weight or less. The weight ratio of the content of the first active material particles 12 to the content of the second active material particles 14 in the electrode composite material mixture is, for example, 3:7, and for example, 4:6, and for example, 5:5, and for example, 6:4, and for example, 7:3.

[0046] The binder 16 in the electrode composite material mixture contains, for example, 0.5% by weight or more and 5% by weight or less, and for example, 1% by weight or more and 3% by weight or less. The conductive additive 18 in the electrode composite material mixture contains, for example, 0.25% by weight or more and 3% by weight or less, and for example, 0.5% by weight or more and 2% by weight or less. The additive in the electrode composite material mixture contains, for example, 0.1% by weight or more and 2% by weight or less, and for example, 0.25% by weight or more and 1% by weight or less.

[0047] In the above manufacturing method, the shear force applied to the adhesive 16 in the step of fibrillating the adhesive 16 (S12) is greater than the shear force applied to the plurality of second active material particles 14 and the conductive additive 18 in the step of making the second covering active material particles (S14). According to this structure, the adhesion between the first active material particles 12 and the adhesive 16 can be improved in the first covering active material particles. Therefore, the tensile strength of the electrode sheet 10 can be improved.

[0048] As an example, the conductive additive 18 used in the above manufacturing method comprises at least one selected from the group consisting of carbon nanotubes and acetylene black. The carbon nanotubes have a tubular shape, and the acetylene black has a chain-like structure. When using a conductive additive 18 having such a shape or structure, the conductive additives 18 are easily entangled with each other, facilitating the formation of conductive paths. On the other hand, when the conductive additive 18 has a tubular shape or a chain-like structure, the conductive additive 18 is easily incorporated into the adhesive 16. However, in this technology, in the step (S14) of producing the second covering active material particles, the conductive additive 18 is pre-attached to the second active material particles 14, thus effectively preventing the conductive additive 18 from being incorporated into the adhesive 16.

[0049] The following describes embodiments related to this technology, but it is not intended to limit this technology to the examples shown in the related embodiments.

[0050] (Example 1)

[0051] <Preparation of Raw Materials>

[0052] As for the active material particles 12 and 14, LiCo was used. 1 / 3 Ni 1 / 3 Mn 1 / 3 O2 single crystal (hereinafter referred to as NCM single crystal, average particle size: 3μm) and LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 A mixture of O2 polycrystalline material (hereinafter referred to as NCM polycrystalline material, average particle size: 10 μm). Polytetrafluoroethylene (PTFE, Chemours) powder is used as the binder 16. Carbon nanotube (CNT, LG Chem) powder is used as the conductive additive 18. Polyvinylidene fluoride (PVdF, Arkema) powder is used as the additive. The weight ratio of NCM single crystal / NCM polycrystalline material / PTFE / CNT / PVdF is 48.7 / 48.7 / 1.4 / 0.75 / 0.5. That is, each active material particle 12, 14 is a mixture of NCM single crystal and NCM polycrystalline material, and the weight ratio of the first active material particle 12 to the second active material particle 14 is 5:5. Hereinafter, the mixture of NCM single crystal and NCM polycrystalline material used as the first active material particle 12 will be referred to as NCM-1, and the mixture of NCM single crystal and NCM polycrystalline material used as the second active material particle 14 will be referred to as NCM-2.

[0053] <First part: Production of active material particles and fibrillation of PTFE>

[0054] like Figure 7AAs shown, firstly, NCM-1 and PTFE were added to a mixer (MP5B, manufactured by Nippon Coke Co., Ltd.) and mixed at 300 rpm for 180 seconds, followed by mixing at 5000 rpm for 500 seconds. This produced the first covering active material particles. The first covering active material particles were then added to a kneader (DSI-5, manufactured by Spindle Manufacturing Co., Ltd., Japan) and mixed at 100°C and 10 rpm for 180 seconds. This imparted a relatively large shear force to the first covering active material particles, causing the PTFE to be fibrillated.

[0055] <The Production of the Second Covering Active Material Particle>

[0056] NCM-2, CNT, and PVdF were added to a mixer (MP5B, manufactured by Nippon Coke Co., Ltd.) and mixed at 10,000 rpm for 10 minutes. This produced the second layer of active material particles.

[0057] <Preparation of Electrode Composite Material Mixture>

[0058] The first and second covering active material particles were added to a mixer (MP5B, manufactured by Nippon Coke Co., Ltd.) and mixed at 300 rpm for 1 minute. This produced an electrode composite material mixture.

[0059] <Electrode Fabrication>

[0060] Electrode sheet 10 was fabricated by rolling the electrode composite material mixture at 160°C and a linear pressure of 0.4 t / cm using a roller press (Tester Industrial Co., Ltd., SA-602). The thickness of electrode sheet 10 is 110 μm.

[0061] (Comparative Example 1)

[0062] In Comparative Example 1, the raw materials were mixed together to prepare an electrode composite material mixture. That is, as shown in... Figure 7B As shown, NCM-1, NCM-2, PTFE, CNT, and PVdF were added to the aforementioned mixer (MP5B, manufactured by Nippon Coke Co., Ltd.), mixed at 300 rpm for 180 seconds, and then mixed at 5000 rpm for 500 seconds. This produced an electrode composite material mixture. The method for preparing electrode sheets from the electrode composite material mixture was the same as in Example 1.

[0063] (Comparative Example 2)

[0064] Comparative Example 2 is an example that adds a kneading machine to Comparative Example 1. That is, as... Figure 7CAs shown, the mixture prepared in Comparative Example 1 using a mixer was added to the kneader described above and mixed at 100°C and 10 rpm for 180 seconds. This produced an electrode composite material mixture. The method for preparing electrode sheets from the electrode composite material mixture was the same as in Example 1.

[0065] (tensile strength)

[0066] Using a punching die, holes were punched in the electrode sheets prepared by the methods of Example 1 and Comparative Examples 1 and 2 to produce dog-bone shaped sample sheets with a width of 4 mm. The thickness of the sample sheet was approximately 5.6 mm. As the measuring apparatus, a Shimadzu AGS-X, a 50 N load cell, and a 50 N clamping fixture were used, with a clamping distance of approximately 4.0 mm and an initial strain rate of 0.33 / s (tensile speed of 1.3 mm / s). Figure 8A The measurement results are shown.

[0067] from Figure 8A The results show that the tensile strength of the electrode sheet 10 in Example 1 is higher than that of the electrode sheet in Comparative Example 1. Furthermore, the tensile strength of the electrode sheet in Comparative Example 2 is higher than that of the electrode sheet in Comparative Example 1. Therefore, by including fibrillated PTFE in the electrode composite material mixture, it can be said that the tensile strength of the electrode sheet made from the electrode composite material mixture is improved.

[0068] (resistance)

[0069] The electrode resistance of the sample plates prepared by the methods of Example 1 and Comparative Examples 1 and 2 was measured using an electrode resistance measuring system (Hioki Electric Co., Ltd., RM2610). The resistance of ). Figure 8B The measurement results are shown.

[0070] from Figure 8B The results show that the resistance of electrode sheet 10 in Example 1 is lower than that of electrode sheet in Comparative Example 2. Therefore, it can be said that when PTFE is fibrillated during the fabrication of the electrode composite material mixture, mixing NCM-1 and PTFE separately, as well as NCM-2, CNTs, and PVdF separately, is more advantageous from the viewpoint of electrode sheet conductivity compared to mixing them all at once. This is believed to be because suppressing the incorporation of CNTs into PTFE results in a larger number of CNTs extending between the NCMs, thereby forming sufficient conductive paths within electrode sheet 10.

[0071] The results above show that the electrode sheet 10 of Example 1 has better tensile strength and conductivity (hereinafter referred to as resistance) than the electrode sheets of Comparative Examples 1 and 2.

[0072] The specific examples of the present invention have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations to the specific examples described above. Hereinafter, variations of the above embodiments are listed.

[0073] In the above embodiment, the present technology was described using electrode 100, which is used as the positive electrode of a lithium-ion secondary battery, as an example. However, the technology disclosed in this specification is not necessarily limited to the positive electrode of a lithium-ion secondary battery, and can also be used as an electrode body used as the negative electrode of a lithium-ion secondary battery. In this case, the active material particles 12 and 14 can be replaced with negative electrode active material particles. Examples of negative electrode active material particles include, for example, carbon materials such as graphite, hard carbon, and soft carbon. Furthermore, regarding the present technology, electrode 100 is not limited to lithium-ion secondary batteries, and can be used similarly for electrode bodies (positive or negative electrodes) of any type of secondary battery.

[0074] In the above embodiments, such as Figure 3 As shown, the manufacturing method of electrode body 100 includes a step of fibrillating adhesive 16 (S12). However, in a modified example, the step of fibrillating adhesive 16 may be omitted, in which case a material that cannot be fibrillated may be used as adhesive 16.

[0075] In the above embodiments, such as Figure 3 As shown, in the method for manufacturing the electrode body 100, after the first covering active material particles are formed (S10), the second covering active material particles are formed (S14). However, in a modified example, the first covering active material particles may be formed after the second covering active material particles are formed. That is, in Figure 3 In the manufacturing method of the electrode body 100 shown, S14 may also be performed before S10.

[0076] Furthermore, the technical elements described in this specification or drawings are technically useful individually or in various combinations, and are not limited to the combinations recited in the claims at the time of application. Additionally, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful.

[0077] (Symbol Explanation)

[0078] 10: Electrode sheet; 12: First active material particle; 14: Second active material particle; 16: Adhesive; 18: Conductive additive; 100: Electrode body; 102: Current collector; 104: Mixer; 106: Blade; 108: Container; 110: Kneader; 112: Blade; 114: Container; 114a: Wall; 116: Pressing device; 118: Roller.

Claims

1. A manufacturing method, which is a method for manufacturing an electrode sheet, wherein, The manufacturing method comprises: The process of producing the first covering active material particles involves mixing an adhesive into at least a plurality of first active material particles. The process of producing a second coated active material particle by mixing at least a conductive additive into a plurality of second active material particles; The process of mixing the first covering active material particles and the second covering active material particles to prepare an electrode composite material mixture; and The electrode composite material mixture is formed into a sheet shape.

2. The manufacturing method according to claim 1, wherein, The process of producing the first covering active material particles includes the process of fibrillating the adhesive by applying at least a shear force to the adhesive.

3. The manufacturing method according to claim 2, wherein, In the process of fibrillating the adhesive, the shear force applied to the adhesive is at least greater than the shear force applied to the plurality of second active material particles and the conductive additive in the process of making the second covering active material particles.

4. The manufacturing method according to claim 1, wherein, The conductive additive comprises at least one selected from the group consisting of carbon nanotubes and acetylene black.

5. The manufacturing method according to claim 1, wherein, The electrode sheet is a freestanding electrode sheet.

6. An electrode sheet, It contains multiple active material particles, binders, and conductive additives. The plurality of active material particles include a plurality of first active material particles covering at least a portion of the surface with the adhesive and a plurality of second active material particles covering at least a portion of the surface with the conductive additive.

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