Dispersing agent for ternary positive electrode material, ternary positive electrode slurry and ternary positive electrode plate

Abstract

The invention relates to a dispersing agent for a ternary positive electrode material, ternary positive electrode slurry and a ternary positive electrode plate. The dispersing agent for the ternary positive electrode material comprises a component A, a component B and an organic solvent. The dispersing agent for the ternary positive electrode material provided by the invention can effectively reduce the initial viscosity of the positive electrode slurry in the mixing preparation process of the positive electrode slurry, and after the positive electrode slurry is stored for a period of time, the positive electrode slurry is still kept stable, the phenomenon of slurry gelatinization is avoided, and the viscosity rise is also avoided; and the flexibility of the ternary positive pole piece prepared from the positive pole slurry can be effectively improved, so that the bending resistance of the ternary positive pole piece is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ternary positive electrode slurry, and in particular to a dispersant for a ternary positive electrode material, a ternary positive electrode slurry and a ternary positive electrode sheet. Background Art

[0002] At present, with the rapid development of 3C electronic products, new energy vehicles and wearable electronic products, the development of lithium-ion batteries has received widespread attention. Ternary positive electrode active materials have become one of the research hotspots for scientific researchers because of their high theoretical specific capacity (for example, the theoretical specific capacity of NCM can reach 278mAh / g), high reaction platform voltage (3.0V-4.4V) and low cost.

[0003] In the process of processing the battery core of ternary lithium-ion battery, the ternary positive electrode material powder, conductive agent, binder and NMP need to be prepared into slurry and coated on aluminum foil. In order to increase the capacity of the battery, the industry has gradually adopted NCM811 with a higher nickel content to replace the previously common NCM111 or NCM523. This leads to an increase in the viscosity of the positive electrode slurry during processing, and as time goes by, the positive electrode slurry itself is very easy to gel, which will seriously affect the coating effect; at the same time, in order to improve processing efficiency, the process method of increasing the solid content in the positive electrode slurry will be selected, which will inevitably lead to problems such as cracking during the coating and drying process, and poor flexibility.

[0004] CN118507730A discloses a dispersant for stabilizing viscosity and reducing electrode sheet resistance for lithium iron phosphate positive electrode slurry, a preparation method and an application thereof. The dispersant mainly comprises the following components, based on the total weight as 100%, 5-30% of sodium dodecyl polyoxyethylene ether sulfate, 5-30% of polyethylene glycol octylphenyl ether, 1-10% of defoaming agent polydimethylsiloxane, 1-10% of emulsifier monolauric acid glyceride, 0.1-5% of pH regulator and 30-60% of organic solvent. The composite effect of anionic surfactant and nonionic surfactant can enhance the dispersion effect. The addition of defoaming agent and emulsifier can reduce surface tension and improve the stability of the composite dispersant. Although the viscosity of the output material is low, the viscosity of the positive electrode slurry still increases after 12h and 18h, and some can even reach more than 8000mPa·s. In addition, its dispersant system is only for lithium iron phosphate positive electrode materials, and the applicable positive electrode materials are single, with low universality. In addition, due to voltage window or matching issues, it cannot be generally used in lithium battery ternary positive electrode materials.

[0005] CN114843516A discloses a dispersant for positive electrode slurry of lithium ion battery, which comprises the following components, based on the total weight of 100wt%, 5-15wt% of component A (one or a combination of at least two of polyvinyl pyrrolidone, polyacrylic amine, hydroxyethyl cellulose and polyoxyethylene copolymer), 15-60wt% of polyether polyurethane containing comb structure, 0.01-1wt% of component B (one or a combination of at least two of hexamethylenediamine and ethanolamine), 0.001-0.1wt% of component C (one or a combination of at least two of polysiloxane, polyether compound and modified organic silicon), and the balance is organic solvent. The positive electrode slurry prepared by the above dispersant has a higher solid content and a lower viscosity. After coating, the obtained positive electrode slurry can also effectively overcome the problems of wrinkles, broken belts or scratches and leakage of foil, and has good flexibility. However, under conditions of high solid content, such as >60% solid content, the viscosity of the corresponding positive electrode slurry is still high, and the problem of high viscosity that still exists at a solid content of 65% or even higher cannot be solved well.

[0006] Therefore, how to develop a dispersant product that can effectively reduce the viscosity of the ternary positive electrode slurry and has high stability, while also improving the flexibility of the ternary positive electrode electrode sheet, has become a problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a dispersant for a ternary positive electrode material, a ternary positive electrode slurry and a ternary positive electrode sheet. The dispersant for a ternary positive electrode material provided by the present invention can effectively reduce the initial viscosity of the positive electrode slurry during the mixing and preparation process of the positive electrode slurry, and after the positive electrode slurry is stored for a period of time, the positive electrode slurry remains stable, the slurry gelation phenomenon does not occur, and the viscosity does not increase. In addition, the flexibility of the ternary positive electrode sheet obtained from the positive electrode slurry can be effectively improved, thereby improving its anti-bending ability.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a dispersant for a ternary positive electrode material, wherein the dispersant for a ternary positive electrode material comprises component A, component B and an organic solvent;

[0010] The structural formula of component A is shown in Formula I:

[0011]

[0012] Wherein, R1 and R2 are each independently selected from substituted or unsubstituted benzamide, substituted or unsubstituted C1-C10 straight chain or branched alkyl, such as C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10 straight chain or branched alkyl, and at least one of said R1 and said R2 is a group containing a benzene ring, and the value range of n is 2-200, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 150, 180 or 200, etc.;

[0013] The structural formula of component B is shown in Formula II:

[0014]

[0015] Wherein, R3 and R4 are each independently selected from any one of substituted or unsubstituted benzoyl, substituted or unsubstituted benzoate, substituted or unsubstituted C1-C20 straight or branched alkyl (for example, C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19 or C20, etc.), and at least one of R3 and R4 is a group containing a benzene ring, and the value range of m is 1-100, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100, etc.

[0016] In the present invention, component A and component B are coordinated, and the benzene ring structure in component A and component B can physically react with the carbon-containing material (conductive agent material) with excessive surface adsorption in the positive electrode slurry and adsorb on its surface. At the same time, the polyether block has an affinity for organic solvents such as N-methylpyrrolidone, thereby being able to generate sufficient steric hindrance to disperse the carbon-containing material. In addition, the repulsive force between component A and component B and the carbon-containing material is sufficient to avoid mutual attraction between the carbon-containing materials, so that the viscosity of the initial slurry is relatively low.

[0017] Generally, in the positive electrode slurry system containing polyvinylidene fluoride (PVDF), the mixed carbon-containing material (conductive material, such as carbon black) will interact with PVDF, and a strong adsorption force will gradually form between the two. When the conductive material with excessive surface adsorption adsorbs different PVDF segments, it will cause the PVDF in the slurry to undergo a state change similar to aggregation, and in severe cases, gel will be formed. The addition of component A can play the role of a dispersant. Specifically, the benzene ring structure in component A has a π-π interaction force inside it, which can make it have strong adsorption performance, and can form a stable adsorption with carbon-containing materials such as conductive carbon black. Further, through the solvated side chain to form a steric hindrance, the carbon-containing materials such as conductive carbon black are in a free state in the slurry, which weakens its surface adsorption, avoids excessive adsorption and excessive binding force to PVDF, and thus avoids the gelation of the positive electrode slurry, and can also maintain the stability of the slurry for a long time.

[0018] In addition, component B of the present invention also has the function of increasing flexibility. Its end group is a group containing a benzene ring structure, which can interact with the lone pair of electrons of the fluorine atoms in PVDF. Therefore, in the drying and film-forming stage, this type of molecule can interact with the fluorine atoms in the PVDF molecules and embed into the crystalline region of PVDF, thereby improving the stretching state of the PVDF molecules and increasing the effective space of the PVDF binder, thereby greatly increasing the flexibility of the ternary positive electrode plate and further improving its anti-bending ability.

[0019] In the present invention, by regulating the value range of n to be 2-200, the influence of component A itself on the viscosity can be avoided. If the value range of m is greater than 200, its own molecular weight is relatively large, which will seriously increase the viscosity of the positive electrode slurry and affect the system stability of the ternary positive electrode slurry; by regulating the value range of m to be 1-100, it is possible to avoid the excessive molecular weight causing the molecular chain length to be too long, resulting in the inability of some areas of the molecule to stretch linearly, affecting the supporting space role of the molecule embedded in the PVDF binder structure, and resulting in reduced flexibility.

[0020] As a preferred technical solution of the present invention, the substituents substituted in R1 and R2 are each independently selected from at least one of a formaldehyde group, an amino group, an amino group protected by a protecting group, a carboxyl group or a hydroxyl group.

[0021] Preferably, in the amino group protected by the protecting group, the protecting group includes tert-butyloxycarbonyl or methyl methylene ether.

[0022] As a preferred technical solution of the present invention, the R1 is selected from Wherein, “*” represents the connection site.

[0023] Preferably, said R2 is selected from Wherein, “*” represents the connection site.

[0024] Preferably, the value range of n is 2-100.

[0025] In the present invention, by further adjusting the value range of n to 2-100, the molecular weight can be adjusted within a suitable range, and the viscosity and stability of the ternary positive electrode slurry system can be more effectively controlled.

[0026] Preferably, the component A comprises

[0027] It should be noted that the component A corresponding to different n values ​​of the present invention can be used alone, or can be used in combination of at least two components A corresponding to different n values.

[0028] As a preferred technical solution of the present invention, the substituents substituted in R3 and R4 are independently selected from any one of halogen, formaldehyde, amino, carboxyl or hydroxyl.

[0029] Preferably, the halogen includes any one of the F element, the Cl element, the Br element or the I element or a combination of at least two of them, preferably the F element.

[0030] As a preferred technical solution of the present invention, the R3 is selected from Wherein, “*” represents the connection site.

[0031] Preferably, said R4 is selected from Wherein, “*” represents the connection site.

[0032] Preferably, the value range of m is 1-10.

[0033] In the present invention, by further regulating the value range of m to 1-10, the chain length can be regulated within a suitable range, effectively controlling its linear stretching in the slurry system, so that the effective space of the PVDF binder is further increased, thereby making the flexibility of the ternary positive electrode sheet better.

[0034] Preferably, the component B comprises

[0035] It should be noted that the component B corresponding to different m values ​​of the present invention can be used alone, or can be used in combination of at least two components B corresponding to different m values.

[0036] Preferably, the component B comprises

[0037] Any one or a combination of at least two of the following.

[0038] As a preferred technical solution of the present invention, based on the total mass of the dispersant for the ternary positive electrode material as 100wt%, the mass of component A is 30wt%-45wt%, for example, 30wt%, 32wt%, 35wt%, 38wt%, 40wt%, 42wt% or 45wt%, etc.

[0039] Preferably, based on the total mass of the dispersant for the ternary positive electrode material as 100wt%, the mass of component B is 5wt%-20wt%, for example, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt% or 20wt%, etc.

[0040] Preferably, based on the total mass of the component A and the component B as 100wt%, the mass of the component A is ≥60wt%, for example, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt% or 90wt%, etc.

[0041] In the present invention, the mass of the component A is regulated to be 30wt%-45wt%, and the mass of the component B is 5wt%-20wt%. Taking the total mass of the components A and B as 100wt%, the mass of the component A is ≥60wt%. The contents of the two are matched to ensure that the dispersant for the ternary positive electrode material is applied to the ternary positive electrode slurry, better maintain the initial viscosity of the slurry and the viscosity after storage for a period of time, maintain the stability of the positive electrode slurry system, and also take into account that the ternary positive electrode sheet has better flexibility, so that the ternary positive electrode slurry and the obtained ternary positive electrode sheet have better performance.

[0042] Preferably, based on the total mass of the dispersant for the ternary positive electrode material being 100wt%, the mass of the organic solvent is 30wt%-70wt%, for example, 30wt%, 40wt%, 50wt%, 60wt% or 70wt%.

[0043] Preferably, the organic solvent comprises N-methylpyrrolidone.

[0044] In a second aspect, the present invention further provides a ternary positive electrode slurry, which comprises the dispersant for the ternary positive electrode material described in the first aspect, a positive electrode active material, a conductive agent, a binder and a solvent.

[0045] As a preferred technical solution of the present invention, the solid content of the ternary positive electrode slurry is ≥70%, for example, 70%, 72%, 75%, 78%, 80% or 90%, etc.

[0046] As a preferred technical solution of the present invention, the ternary positive electrode slurry includes the following components in parts by mass:

[0047]

[0048]

[0049] Specifically, the ternary positive electrode slurry includes the following components in parts by mass:

[0050] The mass fraction of the positive electrode active material is 58 parts to 62 parts, for example, 58 parts, 59 parts, 60 parts, 61 parts or 62 parts.

[0051] The mass proportion of the conductive agent is 0.5 parts to 2.5 parts, for example, 0.5 parts, 1 parts, 1.5 parts, 2 parts or 2.5 parts.

[0052] The mass proportion of the binder is 1.5 parts to 3.5 parts, for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts or 3.5 parts.

[0053] The mass fraction of the dispersant for the ternary positive electrode material is 0.1 part to 0.5 part, for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part or 0.5 part.

[0054] The mass parts of the solvent are 20 parts to 50 parts, for example, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 40 parts or 50 parts.

[0055] In the present invention, only a small amount of dispersant for ternary positive electrode materials needs to be added to the system of ternary positive electrode slurry to achieve good dispersion of the positive electrode slurry and enable the prepared ternary positive electrode sheet to have better flexibility. If too much is added, it will not only fail to further improve the performance of the ternary positive electrode slurry and the ternary positive electrode sheet, but will also bring other adverse effects.

[0056] It should be noted that the present invention does not impose any specific requirements or special limitations on the type of the positive electrode active material. As long as it is a type commonly used by those skilled in the art, it is applicable to the present invention, for example, it may be an NCM system or an NCA system.

[0057] It should be noted that the present invention does not impose any specific requirements or special limitations on the type of the binder. As long as it is a type commonly used by those skilled in the art, it is applicable to the present invention, for example, it may be polyvinylidene fluoride.

[0058] It should be noted that the present invention does not make any specific requirements or special limitations on the type of the conductive agent. As long as it is a type commonly used by technicians in this field, it is applicable to the present invention. For example, it can be any one of conductive carbon black, carbon nanotubes or graphene, or a combination of at least two of them.

[0059] It should be noted that the present invention does not make any specific requirements or special limitations on the type of the solvent. As long as it is a type commonly used by those skilled in the art, it is applicable to the present invention, for example, it can be N-methylpyrrolidone.

[0060] In a third aspect, the present invention further provides a ternary positive electrode plate, comprising a current collector and a positive electrode active material layer disposed on at least one side surface of the current collector, wherein the positive electrode active material layer is prepared from the ternary positive electrode slurry described in the second aspect.

[0061] Compared with the prior art, the present invention has at least the following beneficial effects:

[0062] 1) The dispersant for ternary positive electrode material provided by the present invention is applied to the ternary positive electrode slurry, which can ensure that even in the ternary positive electrode slurry system with a higher solid content (≥70%), it still has a lower viscosity. Specifically, the viscosity of the positive electrode slurry can be reduced from the general 18000mPa·s or more (without adding any dispersant) to the processable range of less than 8000mPa·s.

[0063] 2) The dispersant for ternary positive electrode material provided by the present invention is applied in the ternary positive electrode slurry, which can stabilize the viscosity of the positive electrode slurry. Compared with the positive electrode slurry system with the same solid content, the positive electrode slurry system of the present invention can be maintained for 18 hours or more without gelation of the positive electrode slurry and a significant increase in viscosity.

[0064] 3) The dispersant for ternary positive electrode material provided by the present invention is used in ternary positive electrode slurry. Compared with the ternary positive electrode slurry system with the same solid content, the ternary positive electrode sheet obtained by the ternary positive electrode slurry system of the present invention has extremely high flexibility. When the solid content is 70%, the bending resistance can reach 167 times or more, and when the solid content is 72% and 75%, it can also reach 169 times and 160 times. DETAILED DESCRIPTION

[0065] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0066] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0067] Part of the raw material models and manufacturers of the specific implementation methods of the present invention are as follows:

[0068] The polyvinylidene fluoride binder model is Solvay 5130.

[0069] The ternary cathode material NCM811 was purchased from Ningbo Rongbai New Energy Technology Co., Ltd., model number S8303.

[0070] p-Formylbenzoyl-pentapolyethylene glycol-tert-butyloxycarbonyl (A1), p-Formylbenzoyl-tetrapolyethylene glycol-tert-butyloxycarbonyl (A2), and p-Formylbenzoyl-tripolyethylene glycol-tert-butyloxycarbonyl (A3) were purchased from Shenzhen Meiluo Technology Co., Ltd. with catalog numbers 760505, 760504, and 760503, respectively.

[0071] α-Benzoyl-ω-benzoyloxy-polyoxyethylene (B1) was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd. with a CAS number of 9004-86-8.

[0072] Conductive carbon black model Super P Li is produced by Swiss company Termeco.

[0073] PEG1000 and PEG300 were purchased from Jiangsu Haian Petrochemical Plant.

[0074] The remaining raw materials can be prepared by known methods.

[0075] Example 1

[0076] This embodiment provides a dispersant for a ternary positive electrode material, wherein the dispersant for a ternary positive electrode material comprises 35 wt % of Al 15wt% B1 50 wt% N-methylpyrrolidone.

[0077] The components and contents of the dispersants for the ternary positive electrode materials of Examples 2-7 and Comparative Examples 1-4 are modified based on those of Example 1. The specific modified parameters of Examples 2-7 and Comparative Examples 1-4 are shown in Table 1.

[0078] Table 1

[0079]

[0080] Note: “ / ” indicates that the corresponding raw materials were not added;

[0081] In A2, n is 4, and the structural formula is In A3, n is 3, and the structural formula is In A4, n is 110, and the structural formula is In B6, m is 15, and the structural formula is

[0082] Application Example 1

[0083] This application example provides a ternary positive electrode slurry and a ternary positive electrode sheet, wherein the ternary positive electrode slurry is NCM811 positive electrode slurry, wherein the ternary positive electrode slurry comprises the following components, in parts by mass: 60 parts of NCM811 material, 1.5 parts of conductive carbon black, 2.5 parts of polyvinylidene fluoride, 0.19 parts of the dispersant for the ternary positive electrode material of Example 1, and 27.37 parts of N-methylpyrrolidone, with a solid content of 70%;

[0084] The ternary positive electrode plate is obtained by the following method: first, a polyvinylidene fluoride binder and N-methylpyrrolidone are mixed evenly to obtain a glue A, then a dispersant for the ternary positive electrode material is added to the glue A and mixed evenly to obtain a glue B, then conductive carbon black is added to the glue B and mixed evenly to obtain a glue C, then NCM811 material is added to the glue C and mixed evenly to obtain NCM811 positive electrode slurry, and after scraping and drying at 100° C. for 30 minutes, a ternary positive electrode plate is obtained.

[0085] The components and contents of the ternary positive electrode slurries of Application Examples 2-13 and Comparative Application Examples 1-4 are modified based on the parameters of Application Example 1. The specific modified parameters of Application Examples 2-13 and Comparative Application Examples 1-4 are shown in Table 2. The preparation methods of the ternary positive electrode sheets of Application Examples 2-13 and Comparative Application Examples 1-4 are consistent with those of Application Example 1.

[0086] The positive electrode slurry and ternary positive electrode sheet provided by Application Example 1-13 and Comparative Application Example 1-4 were tested, and the test method was as follows:

[0087] 1) Viscosity of positive electrode slurry (initial viscosity and viscosity after 18 hours of storage)

[0088] Reference standard: GB / T10247-2008.

[0089] Testing instrument and conditions: Rotational viscometer, model Brookfield, rotor No. 4, rotation speed 15rpm-30rpm, test temperature 25℃.

[0090] 2) The number of times the ternary positive electrode sheet can withstand bending

[0091] Manually cut aluminum foil to a size of 12cm×30cm, lay it flat on a glass plate and fix it on four sides; take appropriate positive electrode slurry and evenly apply it to a film using a 400μm film scraper; dry it at 100℃ for 30min; remove it, cut it into strips (12cm×2cm), fold it in half, flatten it, unfold it 180 degrees on the flat surface, and observe whether there is cracking at the crease, which is counted as one time; repeat the rolling and unfolding steps until cracks are observed and count them.

[0092] The specific test results are shown in Table 2.

[0093] Table 2

[0094]

[0095] The test results show that:

[0096] (1) It can be seen from Application Examples 1-3 and 10-11 that the content of each component in the dispersant for ternary positive electrode materials in the present invention is regulated within a suitable addition range, and the content of the dispersant for ternary positive electrode materials in the ternary positive electrode slurry is also within a suitable addition range, which can effectively reduce the viscosity of the slurry and can be maintained for 18 hours or more without the occurrence of the phenomenon of gelation of the positive electrode slurry, and can also make the prepared ternary positive electrode sheet have better flexibility;

[0097] It can be seen from Application Examples 8-9 and Application Example 1 that in the present invention, even in a ternary positive electrode slurry system with a higher solid content (≥70%), it still has a lower viscosity, and the initial viscosity and the viscosity after 18 hours are both lower than 8000mPa·s, and the flexibility of the ternary positive electrode sheet is also relatively high.

[0098] (2) It can be seen from Application Examples 4 and 5 that the mass of component A in the dispersant for ternary positive electrode materials regulated by the present invention is 30wt%-45wt%, the mass of component B is 5wt%-20wt%, and the mass of component A is ≥60wt% based on the total mass of component A and component B as 100wt%. The content of the two components is matched to ensure that the dispersant for ternary positive electrode materials is applied to the ternary positive electrode slurry, and the initial viscosity of the slurry and the viscosity after storage for 18h are better maintained, the stability of the positive electrode slurry system is maintained, and the ternary positive electrode sheet has better flexibility;

[0099] If the quality of component A is too high (Example 4 corresponding to Application Example 4), although it helps to reduce the viscosity, it cannot take into account the better flexibility of the positive electrode sheet; in addition, since component A has a major contribution to the viscosity control of the ternary positive electrode slurry and the overall uniformity control of the slurry, if the quality of component A is too low (Example 5 corresponding to Application Example 5), even if the content of component B is increased, due to the reduced uniformity inside the ternary positive electrode sheet, its anti-bending ability will still be affected, and it cannot show a better anti-bending effect, and the number of anti-bending times is greatly reduced compared to Application Examples 1-3.

[0100] (3) It can be seen from Application Examples 6 and 7 that the value of n in component A is between 50 and 100, which can regulate the molecular weight of component A within a suitable range and effectively control the viscosity and stability of the ternary positive electrode slurry system; the value of m in component B is between 1 and 10, which can regulate its chain length within a suitable range and effectively control its linear stretching in the slurry system, thereby further increasing the effective space of the PVDF binder and making the flexibility of the ternary positive electrode sheet better.

[0101] (4) It can be seen from Application Examples 12-13 and Application Example 1 that the present invention regulates the content of the dispersant for the ternary positive electrode material in the ternary positive electrode slurry to be between 0.1 and 0.5 parts. When the content of the dispersant for the ternary positive electrode material is too much, the slurry viscosity is still reduced and the flexibility of the electrode sheet is improved, but the range of change is small. Compared with the 0.5 parts of the dispersant for the ternary positive electrode material used in Application Example 11, there is no further promotion effect on the improvement of viscosity and flexibility. Instead, it will occupy too much battery mass and affect the energy density of the battery. In addition, from the perspective of material ratio and use cost, it is not recommended to have too high a content; when the content of the dispersant for the ternary positive electrode material is too low, the viscosity control and anti-bending performance of the ternary positive electrode slurry are significantly reduced.

[0102] (5) By comparing Application Example 1, Application Example 3 and Application Example 1, it can be seen that when component A is omitted from the dispersant for the ternary positive electrode material, since component A has a major contribution to the viscosity control of the ternary positive electrode slurry and the overall uniformity control of the slurry, the viscosity and stability of the ternary positive electrode slurry and the anti-bending ability of the ternary positive electrode sheet will be greatly reduced when component A is omitted; when component B is omitted from the dispersant for the ternary positive electrode material, although the viscosity of the ternary positive electrode slurry can be effectively reduced, the anti-bending ability of the ternary positive electrode sheet is greatly reduced.

[0103] (6) By comparing application examples 2, 4 and 1, it can be seen that when PEG1000 is used to replace component A or when PEG300 is used to replace component B, since they do not contain the corresponding benzene ring groups that play a dispersing role, the viscosity of the ternary positive electrode slurry cannot be further reduced, and gelation is severe, and the bending resistance of the ternary positive electrode sheet is greatly reduced.

[0104] In summary, the dispersant for the ternary positive electrode material provided by the present invention can effectively reduce the initial viscosity of the positive electrode slurry during the mixing and preparation process of the positive electrode slurry, and after the positive electrode slurry is stored for a period of time, the positive electrode slurry remains stable, and the slurry gelation phenomenon will not occur, and the viscosity will not increase. In addition, it can also effectively improve the flexibility of the ternary positive electrode sheet obtained from the positive electrode slurry, thereby improving its anti-bending ability.

[0105] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A dispersant for a ternary positive electrode material, characterized in that: The dispersant for the ternary positive electrode material comprises component A, component B and an organic solvent; The structural formula of component A is shown in Formula I: Wherein, R1 and R2 are each independently selected from a substituted or unsubstituted benzamide group, a substituted or unsubstituted C1-C10 straight chain or branched alkyl group, and at least one of the R1 and R2 is a group containing a benzene ring, and the value of n ranges from 2 to 200; The structural formula of component B is shown in Formula II: Wherein, R3 and R4 are each independently selected from any one of a substituted or unsubstituted benzoyl group, a substituted or unsubstituted benzoate group, and a substituted or unsubstituted C1-C20 straight chain or branched alkyl group, and at least one of the R3 and the R4 is a group containing a benzene ring, and the value range of m is 1-100.

2. The dispersant for ternary positive electrode material according to claim 1, characterized in that: The substituents in R1 and R2 are each independently selected from at least one of a formaldehyde group, an amino group, an amino group protected by a protecting group, a carboxyl group or a hydroxyl group; Preferably, in the amino group protected by the protecting group, the protecting group includes tert-butyloxycarbonyl or methyl methylene ether.

3. The dispersant for ternary positive electrode material according to claim 1 or 2, characterized in that: The R1 is selected from Among them, "*" represents the connection site; Preferably, said R2 is selected from Among them, "*" represents the connection site; Preferably, the value range of n is 2-100; Preferably, the component A comprises 4. The dispersant for ternary positive electrode material according to any one of claims 1 to 3, characterized in that: The substituents in R3 and R4 are each independently selected from any one of halogen, formaldehyde, amino, carboxyl or hydroxyl.

5. The dispersant for ternary positive electrode material according to any one of claims 1 to 4, characterized in that: The R3 is selected from Among them, "*" represents the connection site; Preferably, said R4 is selected from Among them, "*" represents the connection site; Preferably, the value range of m is 1-10; Preferably, the component B comprises 6. The dispersant for ternary positive electrode material according to any one of claims 1 to 5, characterized in that: Based on the total mass of the dispersant for the ternary positive electrode material being 100wt%, the mass of the component A is 30wt%-45wt%; Preferably, based on the total mass of the dispersant for the ternary positive electrode material being 100wt%, the mass of the component B is 5wt%-20wt%; Preferably, based on the total mass of the component A and the component B being 100wt%, the mass of the component A is ≥ 60wt%; Preferably, based on the total mass of the dispersant for the ternary positive electrode material being 100wt%, the mass of the organic solvent is 30wt%-70wt%; Preferably, the organic solvent comprises N-methylpyrrolidone.

7. A ternary positive electrode slurry, characterized in that: The ternary positive electrode slurry comprises a dispersant for a ternary positive electrode material according to any one of claims 1 to 6, a positive electrode active material, a conductive agent, a binder and a solvent.

8. The ternary positive electrode slurry according to claim 7, characterized in that: The solid content of the ternary positive electrode slurry is ≥70%.

9. The ternary positive electrode slurry according to claim 7 or 8, characterized in that: The ternary positive electrode slurry comprises the following components in parts by mass:

10. A ternary positive electrode plate, characterized in that: The ternary positive electrode plate comprises a current collector and a positive electrode active material layer disposed on at least one side surface of the current collector, and the positive electrode active material layer is prepared from the ternary positive electrode slurry according to any one of claims 7-9.

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