Dispersing agent, positive electrode slurry, positive electrode sheet, battery and electric device

Abstract

The present application relates to a dispersing agent, a positive electrode slurry, a positive electrode sheet, a battery and an electric device. The dispersing agent comprises an anionic organic chain segment and a non-ionic organic chain segment, wherein the anionic organic chain segment comprises a carbon-carbon main chain and a first group connected to the carbon-carbon main chain; and the non-ionic organic chain segment is connected to the carbon-carbon main chain and comprises a second group, with the polarity of the second group being lower than that of the first group. In the embodiments of the present application, the dispersing agent has excellent dispersing performance and can effectively disperse particles in a positive electrode slurry.

Description

Dispersion agent, positive electrode slurry, positive electrode sheet, battery, and electric device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202410457875.8, filed on April 16, 2024, entitled “Dispersion agent, positive electrode slurry, positive electrode sheet, battery, and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to a dispersion agent, a positive electrode slurry, a positive electrode sheet, a battery, and an electric device. BACKGROUND

[0004] Batteries have characteristics such as high capacity, and are therefore widely used in electronic devices such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, and electric tools, among others.

[0005] Batteries include positive electrode sheets formed by drying and the like of a positive electrode slurry provided on a positive electrode current collector, however, the positive electrode active particles in the positive electrode slurry are prone to agglomeration, resulting in poor performance uniformity and poor leveling of the positive electrode slurry, which affects the performance of the positive electrode sheet and further affects the performance of the battery.

[0006] SUMMARY

[0007] The present application provides a dispersion agent, a positive electrode slurry, a positive electrode sheet, a battery, and an electric device. The dispersion agent of the present application has excellent dispersion performance and can effectively disperse the particles in the positive electrode slurry.

[0008] In a first aspect, the present application provides a dispersion agent, the dispersion agent comprising an anionic organic segment and a nonionic organic segment, the anionic organic segment comprising a carbon-carbon main chain and a first group connected to the carbon-carbon main chain, the nonionic organic segment being connected to the carbon-carbon main chain, and the nonionic organic segment comprising a second group, the second group having a polarity smaller than the first group.

[0009] Thus, the present application provides a dispersion agent by providing an anionic organic segment and a nonionic organic segment in the same compound, wherein one segment plays the role of anchoring to the surface of the positive electrode active particles, and the other plays the role of dispersion, which can anchor the dispersion agent to the surface of the positive electrode active particles while playing the role of dispersing the positive electrode active particles, thereby stabilizing the performance of the positive electrode slurry and making the performance uniform and the leveling better. Moreover, the dispersion agent can also effectively disperse the conductive agent, the binder, and other additives, making the performance of the positive electrode slurry more uniform and the leveling on the positive electrode current collector further improved.

[0010] In some embodiments, the anionic organic segment comprises a segment represented by Formula I,

[0011] R1, R2, and R3 each independently comprise a hydrogen atom, a C1 to C3 alkyl group;

[0012] R4 comprises a single bond or a C1 to C3 alkylene group;

[0013] R5 is a first group, R5 comprises a carboxylic acid or an anion thereof, a sulfonic acid or an anion thereof, a phosphoric acid or an anion thereof, a pyrrolidone or an anion thereof, an amide or an anion thereof, or a carboxylate group;

[0014] n represents a degree of polymerization, and n is greater than or equal to 2.

[0015] In some embodiments, R1, R2, and R3 each independently comprise a hydrogen atom or a methyl group; and / or

[0016] R4 comprises a single bond or a methylene group.

[0017] Thus, the anionic organic segment in the embodiments of the present application can interact with the positive active particles through hydrogen bonds, and bind to the surface of the positive active particles; the anionic organic segment can also play a role in dispersing particles through electrostatic repulsion.

[0018] In some embodiments, the segment represented by Formula I comprises one or more of a segment represented by Formula I-1 to a segment represented by Formula I-14,

[0019] In some embodiments, the second group comprises one or more of an ether bond, a phenyl group, and a hydroxyl group. The second group has relatively weak polarity, and a relatively uniform charge distribution; the second group can interact with non-polar groups in the positive active particles, and bind to the surface of the positive active particles.

[0020] In some embodiments, the non-ionic organic segment containing an ether bond comprises one or more of a polyethylene glycol segment, a polyglycerol segment, and a polypropylene oxide segment. The non-ionic organic segment containing an ether bond is mainly a linear segment, and the segment comprises a carbon-oxygen main chain. The carbon-oxygen main chain has relatively weak polarity, and is easy to interact with non-polar groups on the surface of the positive active particles; moreover, the linear segment is not prone to entanglement, and can effectively play a role of the second group, and play an excellent dispersion role.

[0021] In some embodiments, the non-ionic organic segment containing a phenyl group includes one or more of a polystyrene segment, a polyaniline segment. The non-ionic organic segment is mainly a linear segment, and the segment includes a carbon-carbon main chain and a phenyl group connected to the carbon-carbon main chain. The polarity of the phenyl group is relatively weak, and the phenyl group is easy to interact with the non-polar group on the surface of the positive active particles. Moreover, the linear segment is not easy to entangle, and the second group of the segment can effectively play a role and effectively disperse the particles.

[0022] In some embodiments, the non-ionic organic segment containing a hydroxyl group includes a polyvinyl alcohol segment. The non-ionic organic segment is mainly a linear segment, and the segment is easy to interact with the non-polar group on the surface of the positive active particles. Moreover, the linear segment is not easy to entangle, and the second group of the segment can effectively play a role and effectively disperse the particles.

[0023] In some embodiments, the polyvinyl alcohol segment includes one or more of a polyvinyl alcohol segment and a polypropylene alcohol segment.

[0024] In some embodiments, the non-ionic organic segment includes one or more of a polyethylene glycol segment and a polystyrene segment. The non-ionic organic segment and the anionic organic segment described above cooperate to make the dispersing performance of the dispersant more excellent.

[0025] In some embodiments, the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the non-ionic organic segment is 0.4 to 2.3. When the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the non-ionic organic segment is in the above range, the dispersant can effectively anchor to the surface of the positive active particles and effectively disperse the particles.

[0026] In some embodiments, the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the non-ionic organic segment is 0.7 to 1.5. When the ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the non-ionic organic segment is in the above range, the particles can be further effectively dispersed.

[0027] In some embodiments, the number average molecular weight of the dispersant is 1000 to 20000. When the number average molecular weight of the dispersant is in the above range, the dispersant has excellent suspension capacity and can effectively disperse the particles. Moreover, the dispersant has relatively excellent steric hindrance effect and can effectively disperse the particles.

[0028] In some embodiments, the number average molecular weight of the dispersant is 2000 to 5000. When the number average molecular weight of the dispersant is in the above range, the particles can be effectively dispersed.

[0029] In a second aspect, the embodiments of the present application also provide a positive slurry including the dispersant according to any one of the embodiments of the first aspect of the present application and positive active particles.

[0030] Therefore, the embodiments of the present application can anchor the dispersant to the surface of the positive active particles while playing a good role in dispersing the positive active particles by arranging anionic organic segments and nonionic organic segments in the same compound, so that the performance of the positive slurry is uniform and the leveling property is good.

[0031] In some embodiments, the mass content of the dispersant is 0.3% to 1.1% based on the solid content in the positive slurry. When the mass content of the dispersant is in the above range, the dispersant can basically cover all the positive active particles, so as to effectively disperse the positive active particles; and the molecular chains of the dispersant basically do not intertwine with each other, reducing the risk of flocculation of the positive slurry.

[0032] In some embodiments, the positive active particles include olivine-type phosphate active materials. The olivine-type phosphate active materials are prone to agglomeration and other phenomena, and when the above dispersant is used, the dispersion effect of the olivine-type phosphate active materials can be effectively improved.

[0033] In some embodiments, the olivine-type phosphate active material includes phosphate particles and a carbon coating layer coated on the surface of the phosphate particles. When the carbon coating layer is arranged on the surface, it can play a role in improving the electrical conductivity of the phosphate particles and improving the capacity.

[0034] In some embodiments, the mass content of the carbon coating layer is 3% to 3.6% based on the total mass of the olivine-type phosphate active material. In the case of complete coating or incomplete coating, the dispersant can play an excellent dispersion role on the particles, and the compatibility is high.

[0035] In some embodiments, the olivine-type phosphate active material includes a compound with a general formula of Li x A y Me a M b P 1-c X c Y z , wherein 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or more of S, Si, Cl, B, C, N; and Y includes one or more of O, F.

[0036] In some embodiments, the volume average particle size D50 of the positive electrode active particles is 0.5 μm to 10 μm. v When the particle size of the olivine-type phosphate active material is in the above range, the dispersing effect of the olivine-type phosphate active material can be effectively improved by using the dispersing agent.

[0037] In some embodiments, the volume average particle size D50 of the positive electrode active particles is 0.5 μm to 10 μm. v When the particle size of the olivine-type phosphate active material is in the above range, the dispersing effect of the olivine-type phosphate active material can be effectively improved by using the dispersing agent.

[0038] In a third aspect, the embodiments of the present application further provide a positive electrode tab, which comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, and the positive electrode film layer comprises the dispersing agent and the positive electrode active particles according to any one of the embodiments of the first aspect of the present application.

[0039] In some embodiments, the mass content of the dispersing agent is 0.3% to 1.1% based on the mass of the positive electrode film layer. When the mass content of the dispersing agent is in the above range, the dispersing agent can basically cover all the positive electrode active particles, thereby effectively dispersing the positive electrode active particles; the molecular chains of the dispersing agent basically do not intertwine with each other, thereby reducing the risk of flocculation of the positive electrode slurry, and making the performance of the positive electrode film layer formed by the positive electrode slurry uniform.

[0040] In some embodiments, the positive electrode active particles comprise olivine-type phosphate active materials. The olivine-type phosphate active materials are prone to agglomeration and other phenomena, and the dispersing effect of the olivine-type phosphate active materials can be effectively improved by using the dispersing agent.

[0041] In a fourth aspect, the embodiments of the present application further provide a battery, which comprises the positive electrode tab according to any one of the embodiments of the third aspect of the present application.

[0042] In a fifth aspect, the embodiments of the present application further provide a device using electricity, which comprises the battery cell according to any one of the embodiments of the fourth aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0044] FIG. 1 is a schematic diagram of an embodiment of the battery cell of the present application.

[0045] FIG. 2 is an exploded schematic view of an embodiment of the battery cell of FIG. 1.

[0046] FIG. 3 is a schematic view of an embodiment of a battery module of the present application.

[0047] FIG. 4 is a schematic view of an embodiment of a battery pack of the present application.

[0048] FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4.

[0049] FIG. 6 is a schematic view of an embodiment of an electrical device containing the battery cell of the present application as a power source.

[0050] The accompanying drawings are not necessarily drawn to scale.

[0051] Reference signs are explained as follows: 1, battery pack; 2, upper case; 3, lower case; 4, battery module; 5, battery cell; 51, case; 52, electrode assembly; 53, cover plate; 6, electrical device. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the dispersant, the positive electrode slurry, the positive electrode sheet, the battery, and the electrical device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there can be cases where unnecessary detailed description is omitted. For example, there can be cases where detailed description of matters well known, repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0053] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges are also intended to include any and all sub-ranges of the same, wherein any statement of a range can be read to include any and all sub-ranges within the original stated range. For example, a stated range of 60% to 120% should be considered to include any and all sub-ranges between (and including) the minimum value of 60% and the maximum value of 120%, that is, all sub-ranges beginning with a minimum value of 60% or more and ending with a maximum value of 120% or less, e.g., 60% to 120%, 60% to 121%, 61% to 120%, 62% to 120%, 63% to 120%, 64% to 120%, 65% to 120%, and so forth; the same applies to a stated range of 80% to 110% as well. In other words, a stated range of a-a should be considered to include any and all sub-ranges between (and including) the minimum of "a" and the maximum of "a", that is, all sub-ranges beginning with a minimum value of a or more and ending with a maximum value of a or less, e.g., a-a, a-a, a-a, a-a, a-a, a-a, a-a, a-a, and so forth. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the minimum of 1 and the maximum of 10, that is, all sub-ranges having a minimum of 1 or more and a maximum of 10 or less, e.g., 1 to 10, 3 to 7, 5 to 6, and so forth; as will be apparent to one skilled in the art, other ranges of this type are disclosed herein, and are intended to be implicitly disclosed. In addition, when a range or numeric value is recited herein, unless otherwise stated, the end values of the range are included in the range (e.g., ranges of 0-10 are intended to include the end values 0 and 10). Also, it will be further understood by those within the art that any term in the description and / or the claims that

[0054] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0055] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0056] Unless otherwise specified, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, it is mentioned that the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0057] The battery cell comprises an electrode assembly and an electrolyte, the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator film, the separator film is located between the positive electrode sheet and the negative electrode sheet to isolate the positive electrode sheet and the negative electrode sheet.

[0058] The positive pole piece is formed by coating and drying positive pole slurry on the positive pole current collector, the positive pole slurry comprises positive pole active material, conductive agent, binder and solvent, the positive pole active material in the positive pole slurry may agglomerate, etc., so that the dispersion of the positive pole active material in the positive pole slurry is poor, the performance of the positive pole slurry is uneven, and the flow leveling property of the positive pole slurry on the positive pole current collector is poor.

[0059] In view of this, the embodiments of the present application add a dispersant to the positive pole slurry, the dispersant is provided with anionic organic segment and nonionic organic segment in the same compound, can anchor the dispersant to the surface of the positive pole active particle while playing a good role in dispersing the positive pole active particle, so that the performance of the positive pole slurry is stable, uniform and has good flow leveling property.

[0060] Dispersant

[0061] The embodiments of the present application propose a dispersant.

[0062] The dispersant comprises anionic organic segment and nonionic organic segment, the anionic organic segment comprises carbon-carbon main chain and first group connected to the carbon-carbon main chain, the nonionic organic segment is connected to the carbon-carbon main chain, and the nonionic organic segment comprises second group, the polarity of the second group is smaller than that of the first group.

[0063] The polarity of the first group is stronger, and the first group can be understood as a polar group; the polarity of the second group is weaker, and the second group can comprise weakly polar group or non-polar group. The polarity of the group can be obtained by consulting organic chemistry manual or guide book.

[0064] When the dispersant is applied to the positive pole slurry, in the case that the polarity of the surface of the positive pole active particle is relatively strong, the first group in the anionic organic segment can act on the positive pole active particle through hydrogen bond; the surface of the positive pole active particle is easy to adsorb charged particles due to the strong polarity, which can further enhance the combination with the anionic organic segment, so that the anionic organic segment is anchored to the surface of the positive pole active particle; since the anionic organic segment and the nonionic organic segment are located in the same compound, the nonionic organic segment is distributed outside the positive pole active particle together with the anionic organic segment combined with the surface of the positive pole active particle, the nonionic organic segment can form steric hindrance between particles, reduce the agglomeration between particles, and is beneficial to improve the dispersion performance of the particles, so that the performance of the positive pole slurry is uniform and has good flow leveling property.

[0065] When the dispersant is applied to the positive electrode slurry, in the case that the positive electrode active particle surface mainly includes non-polar groups, the non-ionic organic segment can be anchored to the positive electrode active particle surface due to the second group included in the non-ionic organic segment and the weaker polarity of the second group. Since the non-ionic organic segment and the anionic organic segment are located in the same compound, the anionic organic segment will also be distributed on the surface of the positive electrode active material to form a negative layer as the non-ionic organic segment is combined with the surface of the positive electrode active particle. The particles repel each other by electrostatic repulsion, reducing the attraction between the particles, which is beneficial to improve the dispersion performance of the particles, making the performance of the positive electrode slurry uniform and the leveling better.

[0066] In the case that the positive electrode active particle surface is mainly polar and non-polar, the polar region is anchored to the surface of the positive electrode active particle by the anionic organic segment, and the non-ionic organic segment plays a role in dispersing particles by steric hindrance. The non-polar region is anchored to the surface of the positive electrode active particle by the non-ionic organic segment, and the anionic organic segment plays a role in dispersing particles by electrostatic repulsion. The dispersant is easily and uniformly distributed on the periphery of the positive electrode active particle, and plays an excellent dispersing role on the positive electrode active particle.

[0067] In the case that the positive electrode active particle surface is mainly polar and non-polar, the polar region is anchored to the surface of the positive electrode active particle by the anionic organic segment, and the non-ionic organic segment plays a role in dispersing particles by steric hindrance. The non-polar region is anchored to the surface of the positive electrode active particle by the non-ionic organic segment, and the anionic organic segment plays a role in dispersing particles by electrostatic repulsion. The dispersant is easily and uniformly distributed on the periphery of the positive electrode active particle, and plays an excellent dispersing role on the positive electrode active particle.

[0068] The dispersant in the related art can include two types of polymers, which are mixed by physical means, for example, one type includes anionic polymers, and the other type includes non-ionic polymers. Although the above two types of polymers can also play a dispersing role, when one type of polymer occupies the surface of the particles, it will interfere with the other type of polymer, making the other type of polymer unable to play a good dispersing effect, and the positive electrode slurry still has problems such as agglomeration.

[0069] The anionic organic segment and the non-ionic organic segment of the present application can be located at both ends of the molecular chain, and one type of segment plays the role of anchoring to the surface of the positive electrode active particle, and the other type plays the role of dispersion. Therefore, by arranging the anionic organic segment and the non-ionic organic segment in the same compound, the dispersant can be anchored to the surface of the positive electrode active particle while playing a good dispersing role on the positive electrode active particle, thereby making the performance of the positive electrode slurry stable and uniform, and the leveling better.

[0070] And the dispersant can also effectively disperse the conductive agent, the binder and other auxiliary agents, so that the performance of the positive electrode slurry is more uniform, and the leveling on the positive electrode current collector is further improved.

[0071] [Anionic organic segment]

[0072] The anionic organic segment can interact with the positive active particles through hydrogen bonds and be combined on the surface of the positive active particles; the anionic organic segment can also play a role in dispersing particles through electrostatic repulsion.

[0073] In some embodiments, the anionic organic segment includes a segment shown in Formula I,

[0074] R1, R2 and R3 each independently include a hydrogen atom, a C1 to C3 alkyl group;

[0075] R4 includes a single bond or a C1 to C3 alkylene group;

[0076] R5 is a first group, R5 includes a carboxylic acid or an anion thereof, a sulfonic acid or an anion thereof, a phosphoric acid or an anion thereof, a pyrrolidone or an anion thereof, an amide or an anion thereof, or a carboxylic ester group; the corresponding anion, the cation in the system can include one or more of lithium ion, sodium ion, potassium ion, calcium ion, etc.

[0077] n represents the number of structural units in the segment shown in Formula I, or the degree of polymerization of the segment shown in Formula I, n is any positive integer greater than or equal to 2.

[0078] The C1 to C3 alkyl group can include a methyl group, an ethyl group or a propyl group; optionally, R1, R2 and R3 each independently include a hydrogen atom or a methyl group; further optionally, R1, R2 and R3 each independently include a hydrogen atom. The shorter the length of the branched chain, the higher the content ratio of the first group R5, and the stronger the combination of the first group and the positive active particles.

[0079] The C1 to C3 alkylene group can include a methylene group, an ethylene group or a propylene group; optionally, R4 includes a single bond or a methylene group. The shorter the length of the branched chain, the higher the content ratio of the first group R5, and the stronger the combination of the first group and the positive active particles.

[0080] n represents the number of structural units in the segment shown in Formula I,

[0081] Exemplarily, the segment shown in Formula I includes one or more of a segment shown in Formula I-1 to a segment shown in Formula I-14,

[0082] [Nonionic organic segment]

[0083] The non-ionic organic segment can interact with the positive active particles via the second group and bind to the surface of the positive active particles; the non-ionic organic segment can also play a role in dispersing the particles via steric hindrance.

[0084] In some embodiments, the non-ionic organic segment can have a polymerization degree m greater than or equal to 2, where the polymerization degree refers to the number of repeating units in the non-ionic organic segment, in other words, the non-ionic organic segment is a polymeric organic segment.

[0085] In some embodiments, the second group includes one or more of an ether bond, a phenyl group, and a hydroxyl group. The second group has relatively weak polarity and a relatively uniform charge distribution; the second group can interact with non-polar groups in the positive active particles and bind to the surface of the positive active particles.

[0086] The non-ionic organic segment including an ether bond is mainly a linear segment, and the segment includes a carbon-oxygen main chain. The carbon-oxygen main chain has relatively weak polarity and is easy to interact with non-polar groups on the surface of the positive active particles. Moreover, the linear segment is not prone to entanglement, and can effectively play a role of the second group and achieve excellent dispersion.

[0087] Exemplarily, the non-ionic organic segment including an ether bond includes one or more of a polyethylene glycol segment, a polyglycerol segment, and a polypropylene oxide segment.

[0088] In some embodiments, the non-ionic organic segment including a phenyl group includes one or more of a polystyrene segment and a polyaniline segment. The non-ionic organic segment is mainly a linear segment, and the segment includes a carbon-carbon main chain and an aromatic group such as a phenyl group connected to the carbon-carbon main chain. The phenyl group has relatively weak polarity and is easy to interact with non-polar groups on the surface of the positive active particles. Moreover, the linear segment is not prone to entanglement, and can effectively play a role of the second group and achieve excellent dispersion.

[0089] In some embodiments, the non-ionic organic segment including a hydroxyl group includes a polyvinyl alcohol segment. The non-ionic organic segment is mainly a linear segment, and is easy to interact with non-polar groups on the surface of the positive active particles. Moreover, the linear segment is not prone to entanglement, and can effectively play a role of the second group and achieve excellent dispersion.

[0090] Exemplarily, the polyvinyl alcohol segment includes one or more of a polyvinyl alcohol segment and a polypropylene alcohol segment.

[0091] In some embodiments, the non-ionic organic segment includes one or more of a polyethylene glycol segment and a polystyrene segment, and optionally, the non-ionic organic segment includes a polyethylene glycol segment. The non-ionic organic segment and the anionic organic segment described above cooperate to make the dispersion performance of the dispersant more excellent.

[0092] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-1 and the nonionic organic segment includes a polyethylene glycol segment.

[0093] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-2 and the nonionic organic segment includes a polyethylene glycol segment.

[0094] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by I-3 and the nonionic organic segment includes a polyethylene glycol segment.

[0095] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by I-5 and the nonionic organic segment includes a polyethylene glycol segment.

[0096] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by I-7 and the nonionic organic segment includes a polyethylene glycol segment.

[0097] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by I-11 and the nonionic organic segment includes a polyethylene glycol segment.

[0098] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-1 and the nonionic organic segment includes a polypropylene oxide segment.

[0099] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-2 and the nonionic organic segment includes a polypropylene oxide segment.

[0100] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-1 and the nonionic organic segment includes a polystyrene segment.

[0101] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-1 and the nonionic organic segment includes a glycerol segment.

[0102] As a specific embodiment of the dispersant of the present application, the anionic organic segment of the dispersant can include a segment represented by Formula I-1 and the nonionic organic segment includes a polyvinyl alcohol segment.

[0103] In some embodiments, the ratio of the polymerization degree n of the anionic organic segment to the polymerization degree m of the nonionic organic segment is 0.4 to 2.3, optionally 0.7 to 1.5, for example 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, or a range defined by any two of the aforementioned values.

[0104] When the ratio of the polymerization degree n of the anionic organic segment to the polymerization degree m of the nonionic organic segment is within the aforementioned range, the dispersant can be effectively anchored to the surface of the positive active particles and effectively disperse the particles.

[0105] In some embodiments, the number average molecular weight of the dispersant is 1000 to 20000, optionally 2000 to 5000. For example, the number average molecular weight of the dispersant can be 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, or a range defined by any two of the aforementioned values.

[0106] When the number average molecular weight of the dispersant is within the aforementioned range, the dispersant has excellent suspending ability and can effectively disperse the particles; the dispersant has excellent steric hindrance and can effectively disperse the particles.

[0107] The groups of the organic segment in the embodiments of the present application can be detected by infrared spectrophotometry IR. Specifically, the organic segment is tested by ThermoNicolet Nexus 670 attenuated total reflection Fourier transform infrared spectrometer (FTIR-ATR), and then tested by referring to the standard GB / T 6040-2002, the test range: ATR method 600-4000 cm -1 ; repeatability: ±2 cm -1 ; resolution: better than 4 cm -1 ; transmission depth 0.2-0.6 μm.

[0108] The monomer type of the organic segment in the embodiments of the present application (especially suitable for monomers with a small proportion in the organic segment) can be determined by pyrolysis-gas chromatography-mass spectrometry, and the specific test steps are as follows: accurately weigh 0.5 mg of the sample into a sample cup, fix it on the sample rod, install the pyrolyzer near the gas chromatography GC sample inlet, after the pyrolyzer temperature reaches the set temperature, press the sample button, the sample cup quickly falls into the pyrolysis furnace core by free fall, the volatile components are instantly gasified in the inert gas N2 atmosphere, carried into the gas chromatography column by the carrier gas for separation, finally detected by the flame ionization detector FID or mass spectrometer MS, so as to obtain the gas chromatogram or total ion chromatogram.

[0109] The number average molecular weight of the dispersant in the embodiments of the present application is the meaning known in the art, which can be determined by using the equipment and methods commonly used in the art. The gel permeation chromatography GPC method can be used for testing, and the specific test steps are as follows: take an appropriate amount of sample to be tested (the sample concentration is guaranteed to be 8%-12% obscuration), add 20 ml of deionized water, and simultaneously super 5 min (53 KHz / 120 W) to ensure that the sample is completely dispersed, and then determine the sample according to the GB / T19077-2016 / ISO13320:2009 standard.

[0110] The dispersant in the embodiments of the present application can be formed by block polymerization; for example, the preparation method of the dispersant comprises:

[0111] Step S100, providing a first monomer, initiating the polymerization conditions of the first monomer, so that the first monomer is polymerized into an anionic organic segment;

[0112] Step S200, providing a second monomer, and block polymerizing the second monomer and the anionic organic segment, the anionic organic segment can contain a free radical terminal, on this basis, the second monomer is further polymerized, the second monomer is polymerized to form a nonionic organic segment, and the main chain of the nonionic organic segment is connected with the main chain of the anionic organic segment.

[0113] In the embodiments of the present application, the conditions of block polymerization can be selected according to the conditions known in the art, and the initiators, emulsifiers, chain transfer agents and the like required for block polymerization can be selected according to the materials known in the art, for example, the initiators include ammonium sulfate and the like.

[0114] Exemplarily, the preparation steps of the dispersant can comprise:

[0115] The first monomer, the first initiator and the solvent are added to a container, heated to 40-100°C under the protection of a protective gas such as nitrogen, and stirred for 4-8h to obtain a first part of the polymer segment;

[0116] The second monomer and the second initiator are added to a container, heated to 40-100°C under the protection of a protective gas such as nitrogen, stirred for 4-8 hours, and then treated by dialysis, vacuum distillation, or the like to obtain the desired dispersant.

[0117] For example, the first initiator and the second initiator can each independently include one or more of potassium persulfate, ammonium persulfate, dibenzoyl peroxide, azobisisobutyronitrile, or the like.

[0118] For example, the solvent can include one or more of water, ethanol, dichloromethane, acetone, toluene, N’N’ dimethylformamide, or the like.

[0119] Positive electrode slurry

[0120] The present application also provides a positive electrode slurry.

[0121] The positive electrode slurry includes positive electrode active particles and a dispersant, and the dispersant includes the dispersant of any one of the preceding embodiments.

[0122] The present application can anchor the dispersant to the surface of the positive electrode active particles while effectively dispersing the positive electrode active particles by providing an anionic organic segment and a nonionic organic segment in the same compound, thereby making the performance of the positive electrode slurry uniform and the leveling better.

[0123] In some embodiments, the mass content of the dispersant is 0.3-1.1%, for example 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, or a range between any two of the foregoing values, based on the solid content of the positive electrode slurry. Based on the solid content of the positive electrode slurry means that the total mass of the solid content of the positive electrode slurry is 100%. The solid content does not include volatile components such as solvents, and mainly includes the total content of positive electrode active particles, dispersants, optional conductive agents, and optional binders.

[0124] When the mass content of the dispersant is in the above range, the dispersant can basically cover all the positive electrode active particles, thereby effectively dispersing the positive electrode active particles; and the molecular chains of the dispersant do not substantially entangle with each other, thereby reducing the risk of flocculation of the positive electrode slurry.

[0125] In some embodiments, the mass content of the positive electrode active particles is 80-99%, for example 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or a range between any two of the foregoing values, based on the solid content of the positive electrode slurry.

[0126] The positive electrode active particles and the dispersant described above are used in combination, and in particular, the dispersant in the mass content described above and the positive electrode active particles in the mass content described above are used in combination, which can effectively disperse the positive electrode active particles, improve the performance uniformity of the positive electrode slurry, and improve the leveling property of the positive electrode slurry.

[0127] In some embodiments, the positive electrode active particles can employ materials known in the art for use in battery cells. As an example, the positive electrode active particles can include at least one of the following materials: active materials of a layered structure (such as materials of a ternary, lithium / sodium nickelate, lithium / sodium cobaltate, lithium / sodium manganate, lithium / sodium-rich layered, and rock salt phase layered, etc.), olivine-type phosphate active materials, positive electrode active materials of a spinel structure (such as spinel lithium manganate, spinel lithium nickel manganate, lithium-rich spinel lithium manganate, and lithium nickel manganate, etc.). Alternatively, the positive electrode active particles can include olivine-type phosphate active materials.

[0128] Exemplarily, the general formula of the positive electrode active material of a layered structure is: Li x A y Ni a Co b Mn c M (1-a-b-c) Y z , 0≤x≤2.1, 0≤y≤2.1, and 0.9≤x+y≤2.1; 0≤a≤1, 0≤b≤1, 0≤c≤1, and 0.1≤a+b+c≤1; 1.8≤z≤3.5; A includes one or more of Na, K, Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; Y includes one or more of O, F. Alternatively, y=0.

[0129] Specifically, the positive electrode active material of a layered structure can include one or more of lithium cobaltate LCO, lithium nickelate LNO, lithium manganate LMO, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), and LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523).

[0130] Exemplarily, the general formula of the olivine-type phosphate active material is: Li x A y Me a Mb P 1-c X c Y z wherein 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A comprises one or more of Na, K, Mg; Me comprises one or more of Mn, Fe, Co, Ni; M comprises one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X comprises one or more of S, Si, Cl, B, C, N; Y comprises one or more of O, F. Specifically, the olivine-type phosphate active material comprises one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0131] Exemplarily, the general formula of the spinel-structured positive electrode active material is: Li x A y Mn a M 2-a Y z wherein 0≤x≤2, 0≤y≤1, and 0.9≤x+y≤2; 0.5≤a≤2; 3≤z≤5; A comprises one or more of Na, K, Mg; M comprises one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; Y comprises one or more of O, F. Specifically, the spinel-structured positive electrode active material comprises one or more of LiMn2O4, LiNi 0.5 Mn 1.5 O4, LiCr 0.3 Mn 1.7 O4, Li 1.1 Al 0.1 Mn 1.9 O4, Li2Mn2O4, and Li 1.5 Mn2O4.

[0132] The battery cell will be accompanied by the de-intercalation and consumption of active ions such as Li during the charging and discharging process, and the molar content of Li is different when the battery cell is discharged to different states. In the enumeration of the positive electrode active material in the embodiments of the present application, the molar content of Li is the initial state of the material, i.e. the state before feeding, and the positive electrode active material is applied to the battery system, and the molar content of Li may change after charging and discharging cycles.

[0133] In the enumeration of the positive electrode active material in the embodiments of the present application, the molar content of oxygen O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen O to change. In fact, the molar content of oxygen O will fluctuate.

[0134] Alternatively, the positive electrode active particles can include olivine-type phosphate active materials. When water is used as the solvent, the olivine-type phosphate active materials are prone to agglomeration and other phenomena. When the above dispersing agent is used in combination, the dispersion effect of the olivine-type phosphate active materials can be effectively improved.

[0135] In the embodiments of the present application, each of the above positive electrode active particles can also be a modified compound. The modified compound can be a doping modification and / or a surface coating modification of the positive electrode active material. For example, doping modification can be performed by doping a transition metal element, and coating modification can be performed by coating a carbon layer on the surface of the material.

[0136] For example, the olivine-type phosphate active material can include a carbon coating layer, or can not include a carbon coating layer. When a carbon coating layer is provided on the surface, the carbon coating layer can coat the phosphate particles and improve the electrical conductivity of the phosphate particles, thereby improving the capacity.

[0137] When the olivine-type phosphate active material is coated with a carbon coating layer, the mass content of the carbon coating layer is 3% to 3.6%, for example, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, or a range composed of any two of the above values, based on the total mass of the olivine-type phosphate active material. The carbon coating layer can be completely coated or incompletely coated. In the case of complete coating or incomplete coating, the dispersing agent can have excellent dispersion effect on the particles and has high compatibility.

[0138] In the case of complete coating, the surface properties of the olivine-type phosphate active material are determined by the carbon coating layer. The carbon coating layer is mainly non-polar structure, and the carbon coating layer is not easy to adsorb charged particles. It is easy to combine with non-ionic organic segments. The anionic organic segments are anchored on the carbon surface of the positive electrode active particles, and the anionic organic segments play a role in dispersing the particles through electrostatic repulsion.

[0139] The carbon coating can also be incomplete, in which case part of the phosphate located in the core is exposed, the surface properties of the olivine-type phosphate active material are determined by the carbon coating layer and the exposed phosphate, the carbon coating layer surface is easy to combine with non-ionic organic segments, the non-ionic organic segments are anchored on the carbon surface of the positive active particles, and the anionic organic segments play a role in dispersing particles through electrostatic repulsion. The exposed phosphate surface is easy to combine with through anionic organic segments, and non-ionic organic segments play a role in dispersing particles through steric hindrance, thereby playing an excellent dispersion effect on the positive active particles.

[0140] Of course, the surface of the olivine-type phosphate active material can not contain a carbon coating layer, and the surface thereof is determined by the phosphate, the phosphate surface is easy to combine with through anionic organic segments, and non-ionic organic segments play a role in dispersing particles through steric hindrance, thereby playing an excellent dispersion effect on the positive active particles.

[0141] In some embodiments, the olivine-type phosphate active material is in a particulate form, and the volume average particle size D v 50 is 0.5 μm to 10 μm, optionally 0.5 μm to 2 μm, and further optionally 1.20 μm to 1.40 μm, for example 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range composed of any two of the above values. When the particle size of the olivine-type phosphate active material is in the above range, especially when the particle size is relatively small, agglomeration and other problems are likely to occur during the mixing and dispersion of the slurry; and the use of the above dispersant can effectively improve the dispersion effect of the olivine-type phosphate active material.

[0142] In the embodiments of the present application, the volume average particle size D v 50 is the meaning known in the art, and the volume average particle size D v 50 of the material refers to the particle size corresponding to 50% in the volume distribution, which can be detected by using devices and methods known in the art. A certain amount of olivine-type phosphate active material is taken as a sample, or olivine-type phosphate active material in the positive slurry is washed with water and dried to obtain a sample. According to the test standard GB / T 19077-2016, the volume average particle size D v 50 is tested by a Mastersizer 2000E laser particle size analyzer.

[0143] In some embodiments, the positive electrode slurry further optionally comprises a positive electrode conductive agent. The present embodiments do not have particular limitations on the type of positive electrode conductive agent, which may, for example, include at least one of super-p carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is ≤5% based on the total mass of the solid content in the positive electrode slurry being 100%.

[0144] In some embodiments, the positive electrode slurry further optionally comprises a positive electrode binder. The present embodiments do not have particular limitations on the type of positive electrode binder, which may, for example, include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin. In some embodiments, the mass percentage of the positive electrode binder is ≤5% based on the total mass of the solid content in the positive electrode slurry being 100%.

[0145] Positive electrode tab

[0146] The present embodiments further provide a positive electrode tab.

[0147] The positive electrode tab comprises a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer comprising positive electrode active particles and a dispersant, the dispersant comprising the dispersant of any of the preceding embodiments. The positive electrode tab can be formed by disposing the positive electrode slurry of any of the preceding embodiments on the positive electrode current collector.

[0148] The present embodiments can anchor the dispersant to the surface of the positive electrode active particles while effectively dispersing the positive electrode active particles by disposing an anionic organic segment and a nonionic organic segment in the same compound, thereby making the performance of the positive electrode slurry uniform and the leveling property better, and making the performance of the positive electrode film layer uniform and the leveling property better.

[0149] In some embodiments, the mass content of the dispersant is 0.3% to 1.1%, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, or a range between any two of the foregoing values, based on the mass of the positive electrode film layer.

[0150] When the mass content of the dispersant is within the foregoing range, the dispersant can substantially cover all of the positive electrode active particles, thereby effectively dispersing the positive electrode active particles; the molecular chains of the dispersant are substantially unlikely to intertwine with each other, thereby reducing the risk of flocculation of the positive electrode slurry, and making the performance of the positive electrode film layer formed by the positive electrode slurry uniform.

[0151] In some embodiments, the cathode active particles have a mass content of 80% to 99%, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or a range between any two of the aforementioned values, based on the mass of the cathode film layer.

[0152] The cathode active particles and the dispersant described above, especially the dispersant having the mass content described above and the cathode active particles having the mass content described above, can effectively disperse the cathode active particles, improve the performance uniformity of the cathode slurry, and make the cathode film layer formed by the cathode slurry have uniform performance.

[0153] In some embodiments, the cathode active particles can be made of materials commonly known in the art for use in battery cells. As an example, the cathode active particles can include at least one of the following materials: active materials having a layered structure (such as materials having a ternary, lithium / sodium nickelate, lithium / sodium cobaltate, lithium / sodium manganate, lithium / sodium-rich layered, and rock salt phase layered structure), olivine-type phosphate active materials, and cathode active materials having a spinel structure (such as spinel lithium manganate, spinel lithium nickel manganate, lithium-rich spinel lithium manganate, and lithium nickel manganate). Alternatively, the cathode active particles can include olivine-type phosphate active materials, which are prone to agglomeration and other phenomena when water is used as a solvent. In combination with the dispersant described above, the dispersing effect of the olivine-type phosphate active materials can be effectively improved.

[0154] In some embodiments, the cathode electrode sheet includes a cathode current collector and a cathode film layer disposed on at least one surface of the cathode current collector and including a cathode active material. For example, the cathode current collector has two opposite surfaces in the thickness direction of the cathode current collector, and the cathode film layer is disposed on either one or both of the two opposite surfaces of the cathode current collector.

[0155] In some embodiments, the cathode current collector can be a metal foil or a composite current collector. As an example of the metal foil, an aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material of the metal material layer can include at least one of aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0156] The positive electrode film layer is usually formed by coating a positive electrode slurry on a positive electrode current collector, and then drying and rolling, etc. The positive electrode slurry is usually formed by dispersing and uniformly stirring a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0157] Optionally, the coating method is extrusion coating, transfer coating, blade coating, spray coating, etc.

[0158] Optionally, the drying method is air blowing, infrared heating, microwave heating, nano-steam heating, etc., and the heating temperature is 50-180°C.

[0159] Optionally, the rolling is cold rolling or hot rolling, and the rolling temperature is 20-180°C.

[0160] Battery cell

[0161] The present application also provides a battery cell.

[0162] The battery cell, also known as a rechargeable battery or a storage battery, refers to a battery that can be activated by charging after discharging to continue use. In general, the battery cell includes an electrode assembly and an electrolyte, the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator film, the separator film is arranged between the positive electrode sheet and the negative electrode sheet, and mainly plays a role in preventing the positive electrode and the negative electrode from short-circuiting, while allowing active ions to pass through.

[0163] In some embodiments, the battery cell includes the positive electrode sheet of any of the above embodiments, and the positive electrode sheet has stable performance.

[0164] [Negative electrode sheet]

[0165] In some embodiments, the battery cell further includes a negative electrode sheet.

[0166] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two opposite surfaces in the thickness direction of itself, and the negative electrode film layer is arranged on any one or both of the two opposite surfaces of the negative electrode current collector.

[0167] The negative electrode active material can be any known in the art for use in a battery cell. As an example, the negative electrode active material can include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate. The silicon-based material can include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material can include at least one of elemental tin, tin oxide, and tin alloy material.

[0168] In some embodiments, the negative electrode film layer can further optionally include a negative electrode conductive agent. The embodiments of the present application do not have a particular limitation on the type of the negative electrode conductive agent, and as an example, the negative electrode conductive agent can include at least one of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage content of the negative electrode conductive agent is ≤ 5% based on the total weight of the negative electrode film layer.

[0169] In some embodiments, the negative electrode film layer can further optionally include a negative electrode binder. The embodiments of the present application do not have a particular limitation on the type of the negative electrode binder, and as an example, the negative electrode binder can include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage content of the negative electrode binder is ≤ 5% based on the total weight of the negative electrode film layer.

[0170] In some embodiments, the negative electrode film layer can further optionally include other auxiliary agents. As an example, the other auxiliary agents can include a thickening agent, such as carboxymethyl cellulose sodium (CMC-Na), PTC thermistor material, etc. In some embodiments, the mass percentage content of the other auxiliary agents is ≤ 2t% based on the total weight of the negative electrode film layer.

[0171] In some embodiments, the negative electrode current collector can employ a metal foil or a composite current collector. As an example of the metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material in the metal material layer can include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer can include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0172] The negative electrode film layer is generally formed by coating a negative electrode slurry on a negative electrode current collector, drying, and cold-pressing. The negative electrode slurry is generally formed by dispersing and uniformly stirring a negative electrode active material, an optional conductive agent, an optional binder, and other optional auxiliary agents in a solvent. The solvent can be N-methyl pyrrolidone (NMP) or deionized water, but is not limited thereto.

[0173] The negative electrode sheet does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of the embodiments of the present application further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0174] [Electrolyte]

[0175] In some embodiments, the battery cell further includes an electrolyte.

[0176] During the charge and discharge process of a battery cell, active ions are embedded and released back and forth between the positive and negative electrodes, and the electrolyte conducts the active ions between the positive and negative electrodes. The present application embodiment does not specifically limit the type of electrolyte, and the electrolyte can be selected based on actual needs.

[0177] The electrolyte solution includes an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not particularly limited and can be selected according to actual needs.

[0178] As an example, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0179] As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0180] In some embodiments, the electrolyte solution can further include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain performance of the battery, such as an additive that can improve overcharge performance of the battery, an additive that can improve high-temperature performance of the battery, an additive that can improve low-temperature power performance of the battery, and the like.

[0181] [Separator]

[0182] In some embodiments, the battery cell can further include a separator. The type of the separator is not particularly limited in the embodiments of the present application, and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0183] In some embodiments, the material of the separator can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0184] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a stacking process.

[0185] In some embodiments, the battery cell can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte solution described above.

[0186] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, and the like. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0187] The shape of the battery cell is not particularly limited in the embodiments of the present application, and can be cylindrical, square, or any other shape. FIG. 1 is a battery cell 5 having a square structure as an example.

[0188] In some embodiments, as shown in FIG. 2, the outer package can include a shell 51 and a cover plate 53. The shell 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly 52 through a winding process and / or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte solution is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to requirements.

[0189] The preparation method of the battery cell of the embodiments of the present application is known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, the separator, the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a stacking process, the electrode assembly is placed in an outer package, the electrolyte is injected after drying, and the battery cell is obtained through processes such as vacuum packaging, standing, formation, shaping, etc.

[0190] In some embodiments of the embodiments of the present application, the battery cell according to the embodiments of the present application can be assembled into a battery module, and the number of battery cells contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0191] FIG. 3 is a schematic view of a battery module 4 as an example. As shown in FIG. 3, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0192] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0193] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0194] FIGS. 4 and 5 are schematic views of a battery pack 1 as an example. As shown in FIGS. 4 and 5, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, the upper box body 2 is used to cover the lower box body 3, and forms a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0195] Electric device

[0196] The embodiments of the present application also provide an electric device, which includes at least one of the battery cell, the battery module or the battery pack according to the embodiments of the present application. The battery cell, the battery module or the battery pack can be used as a power source of the electric device, or can be used as an energy storage unit of the electric device. The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0197] The electric device can select the battery cell, the battery module or the battery pack according to the use requirements thereof.

[0198] FIG. 6 is a schematic view of an electric device 6 as one example. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the demand of the electric device 6 for high power and high energy density, a battery pack or a battery module can be used.

[0199] The electric device as another example can be a mobile phone, a tablet, a notebook computer, etc. The electric device generally requires thinness and lightness, and a battery monomer can be used as a power source.

[0200] Embodiments

[0201] The following examples describe the present application in more detail, which are only used for illustrative purposes, and various modifications and changes within the scope of the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods, and can be used directly without further treatment, and the instruments used in the examples are commercially available.

[0202] Example 1 Preparation of positive electrode slurry

[0203] Preparation of dispersant

[0204] 0.1 parts by weight of initiator potassium persulfate, 50 parts by weight of acrylic acid, 500 parts by weight of water were added to the reaction vessel, and stirred at 80°C for 4 hours under nitrogen protection;

[0205] 0.1 parts by weight of initiator potassium persulfate, 50 parts by weight of ethylene glycol were added to the reaction vessel, and stirred at 80°C for 4 hours under nitrogen protection, and the small molecule monomers not completely polymerized were removed by vacuum distillation to obtain the dispersant.

[0206] Preparation of positive electrode slurry

[0207] The positive electrode active material, the dispersant, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) were fully stirred and mixed in an appropriate amount of solvent deionized water to form a uniform positive electrode slurry, wherein the positive electrode active material, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) were added in a weight ratio of 95:2:1.

[0208] The positive electrode active material includes lithium iron phosphate LiFePO4 and a carbon coating layer provided on the surface of lithium iron phosphate, and the mass content of the carbon coating layer is 3.2% based on the total mass of the positive electrode active material.

[0209] Comparative Example 1

[0210] An anode slurry was prepared in a similar manner to Example 1, except that the dispersant in the anode slurry was polyacrylic acid.

[0211] Comparative Example 2

[0212] An anode slurry was prepared in a similar manner to Example 1, except that the dispersant in the anode slurry was polyethylene glycol.

[0213] Examples 2-1 to 2-5

[0214] An anode slurry was prepared in a similar manner to Example 1, except that at least one of the polymerization degree of the anionic organic segment and the polymerization degree of the nonionic organic segment in the dispersant in the anode slurry was adjusted.

[0215] Examples 3-1 to 3-9

[0216] An anode slurry was prepared in a similar manner to Example 1, except that the type of the dispersant in the dispersant in the anode slurry was adjusted,

[0217] wherein,

[0218] Examples 3-1 to 3-5, the type of the anionic organic segment in the dispersant was adjusted;

[0219] Examples 3-6 to 3-9, the type of the nonionic organic segment in the dispersant was adjusted.

[0220] Examples 4-1 and 4-2

[0221] An anode slurry was prepared in a similar manner to Example 1, except that the data molecular weight of the dispersant in the anode slurry was adjusted.

[0222] Examples 5-1 to 5-3

[0223] An anode slurry was prepared in a similar manner to Example 1, except that the carbon-coating amount of the anode active particles in the anode slurry was adjusted.

[0224] Example 6

[0225] An anode slurry was prepared in a similar manner to Example 1, except that the volume average particle size D50 of the anode active particles in the anode slurry was adjusted. v 50 was adjusted.

[0226] Preparation of a battery cell

[0227] 1. Preparation of an anode electrode sheet

[0228] Aluminum foil is used as the positive current collector.

[0229] The positive electrode slurry prepared in each example and comparative example is uniformly coated on the surface of the positive current collector aluminum foil, and after drying and cold pressing, a positive electrode tab is obtained.

[0230] 2. Preparation of negative electrode tab

[0231] Copper foil is used as the negative current collector.

[0232] The negative active material artificial graphite, the binder styrene-butadiene rubber (SBR), the thickening agent sodium carboxymethyl cellulose (CMC-Na), and the conductive agent carbon black (Super P) are mixed in a weight ratio of 96.2:1.8:1.2:0.8 in an appropriate amount of solvent deionized water to form a uniform negative electrode slurry. The negative electrode slurry is uniformly coated on the surface of the negative current collector copper foil, and after drying and cold pressing, a negative electrode tab is obtained.

[0233] 3. Separation film

[0234] A porous polyethylene (PE) film is used as the separation film.

[0235] 4. Preparation of electrolyte

[0236] In an environment with a water content of less than 10 ppm, non-aqueous organic solvent ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain an electrolyte solvent, and then lithium salt lithium hexafluorophosphate is mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0237] 5. Preparation of battery monomer

[0238] The above positive electrode tab, separation film, and negative electrode tab are stacked in order, with the separation film between the positive electrode tab and the negative electrode tab to play a separation role, and then wound to obtain an electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum packaging, standing, formation, shaping, and other processes, a lithium ion battery is obtained.

[0239] Performance test

[0240] 1. Slurry state test of positive electrode slurry

[0241] Take the positive electrode slurry, observe the flow state of the slurry, and classify according to the following standards:

[0242] If the positive electrode slurry has no agglomeration and flows in a continuous water flow, it is recorded as excellent;

[0243] If the positive electrode slurry has no obvious agglomeration and has flowability, but cannot form a continuous water flow, it is recorded as good;

[0244] If the positive electrode slurry is substantially not in a flowable state, such as a paste, etc., it is recorded as poor.

[0245] 2. Sieving time test of the positive electrode slurry

[0246] Take 500 ml of the positive electrode slurry, pour the positive electrode slurry through a 150-mesh filter into a beaker (the beaker is provided with a scale), record the time taken for the beaker to contain 400 ml of the positive electrode slurry, which is the sieving time. The faster the sieving time, the less likely the slurry is to agglomerate.

[0247] 3. Viscosity test of the positive electrode slurry

[0248] Add the positive electrode slurry to the measuring cup, load a No. 63 rotor in the rotary viscometer, adjust the rotor to be above the scale line of the positive electrode slurry, adjust the rotation speed of the rotary viscometer to 13 rmp, and read the viscosity after the reading is stable.

[0249] 4. Static gelation time of the positive electrode slurry

[0250] Take the positive electrode slurry and store it at room temperature, record the time when the positive electrode slurry gels, the longer the static gelation time, the more stable the slurry.

[0251] Test results

[0252] The test results are shown in Tables 1 and 2.

[0253] Table 1

[0254] In Table 1, n represents the degree of polymerization of the anionic organic segment; m represents the degree of polymerization of the nonionic organic segment.

[0255] As can be seen from Table 1, in Comparative Examples 1 and 2, polyacrylic acid or polyethylene glycol is added alone as a dispersant to the positive electrode slurry, and the dispersibility of the particles in the positive electrode slurry is relatively poor; when a mixture of polyacrylic acid and polyethylene glycol is added as a dispersant to the positive electrode slurry, the polyacrylic acid and the polyethylene glycol each play a dispersing role, which can improve the dispersibility of the particles in the positive electrode slurry to a certain extent, but the performance of the slurry is unstable and is prone to problems such as agglomeration.

[0256] Compared with the comparative examples, the anionic organic segment and the nonionic organic segment are combined in the same molecular chain in the embodiments of the present application, one of which plays an anchoring role on the surface of the positive electrode active particles, and the other plays a dispersing role, so that the dispersant can play a good role in dispersing the positive electrode active particles, thereby making the performance of the positive electrode slurry stable and uniform, and having good leveling property.

[0257] The dispersing performance of the dispersant is further improved when the ratio of the polymerization degree of the anionic organic segment to the nonionic organic segment is 0.4 to 2.3, and more preferably 0.7 to 1.5. In this case, the particles in the positive electrode slurry are uniformly dispersed, and the performance is stable and uniform, and the leveling property is good.

[0258] The dispersing performance of the dispersant is further adjusted by adjusting the type of the anionic organic segment or the nonionic organic segment, so that the particles in the positive electrode slurry are uniformly dispersed, and the performance is stable and uniform, and the leveling property is good.

[0259] The dispersing performance of the dispersant is further improved by adjusting the number average molecular weight of the dispersant. In particular, when the number average molecular weight is 2000 to 10000, and more preferably 2000 to 5000, the dispersing performance is further improved, so that the particles in the positive electrode slurry are uniformly dispersed, and the performance is stable and uniform, and the leveling property is good.

[0260] Table 2

[0261] As shown in Table 2, the carbon coating amount of the positive electrode active particles in Examples 5-1 to 5-3 is adjusted. The mass content of the carbon coating layer is 3% to 3.6% based on the total mass of the positive electrode active particles. The dispersing effect of the dispersant on the particles is excellent, which indicates that the dispersant is suitable for systems with different carbon coating amounts, and has a wide application range.

[0262] The volume average particle size D v 50 of the positive electrode active particles is adjusted. When the volume average particle size is 0.5 μm to 10 μm, and more preferably 0.5 μm to 2 μm, and further more preferably 1.20 μm to 1.40 μm, the dispersing performance of the dispersant on the positive electrode active particles is excellent.

[0263] Although the illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments cannot be interpreted as limiting the present application, and the embodiments can be changed, replaced and modified without departing from the spirit, principles and scope of the present application.

Claims

1. A dispersant comprising an anionic organic segment and a nonionic organic segment, the anionic organic segment comprising a carbon-carbon backbone and a first group attached to the carbon-carbon backbone, the nonionic organic segment being attached to the carbon-carbon backbone, and the nonionic organic segment comprising a second group, the second group being less polar than the first group.

2. The dispersant of claim 1, wherein, The anionic organic segment comprises a segment of formula I, R1, R2, and R3 each independently comprise a hydrogen atom, a C1 to C3 alkyl group; R4 comprises a single bond or a C1 to C3 alkylene group; R5 is the first group, R5 comprising a carboxylic acid or an anion thereof, a sulfonic acid or an anion thereof, a phosphoric acid or an anion thereof, a pyrrolidone or an anion thereof, an amide or an anion thereof, or a carboxylate group; n represents a degree of polymerization, and n is equal to or greater than 2.

3. The dispersant of claim 2 wherein, R1, R2, and R3 each independently comprise a hydrogen atom or a methyl group; and / or R4 comprises a single bond or a methylene group.

4. The dispersant of claim 2 or 3, wherein, The segments of Formula I include one or more of segments of Formula I-1 through I-14, 5. The dispersant of any one of claims 1 to 4 wherein, The second group comprises one or more of an ether bond, a phenyl group, and a hydroxyl group.

6. The dispersant according to claim 5, wherein, The nonionic organic segment containing the ether bond comprises one or more of a polyethylene glycol segment, a polyglycerol segment, and a polypropylene oxide segment; and / or The nonionic organic segment containing the phenyl group comprises one or more of a polystyrene segment, a polyaniline segment; and / or The nonionic organic segment containing the hydroxyl group comprises a polyenol segment.

7. The dispersant of claim 6 wherein, The polyenol segment comprises one or more of a polyvinyl alcohol segment and a polypropylene alcohol segment.

8. The dispersant of claim 7 wherein, The nonionic organic segment comprises one or more of a polyethylene glycol segment and a polystyrene segment.

9. The dispersant of any one of claims 1 to 8 wherein, The ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is 0.4 to 2.

3.

10. The dispersant of claim 9 wherein, The ratio of the degree of polymerization of the anionic organic segment to the degree of polymerization of the nonionic organic segment is 0.7 to 1.

5.

11. The dispersant of any one of claims 1 to 10 wherein, The number average molecular weight of the dispersant is 1000 to 20000.

12. The dispersant of claim 11, wherein, The number average molecular weight of the dispersant is 2000 to 5000.

13. A positive electrode slurry comprising positive electrode active particles and the dispersant according to any one of claims 1 to 12.

14. The positive electrode slurry of claim 13, wherein, The mass content of the dispersant is 0.3% to 1.1% based on the solid content in the positive electrode slurry.

15. The positive electrode slurry according to claim 13 or 14, wherein, The positive electrode active particles comprise olivine-type phosphate active material.

16. The positive electrode slurry of claim 15, wherein, The olivine-type phosphate active material comprises phosphate particles and a carbon coating layer coated on the surface of the phosphate particles.

17. The positive electrode slurry of claim 16, wherein, The mass content of the carbon coating layer is 3% to 3.6% based on the total mass of the olivine-type phosphate active material.

18. The positive electrode paste according to any one of claims 15 to 17, wherein, The olivine-type phosphate active material includes a compound of a general formula of Li x A y Me a M b P 1-c X c Y z , wherein 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or several of Na, K, Mg; Me includes one or several of Mn, Fe, Co, Ni; M includes one or several of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or several of S, Si, Cl, B, C, N; Y includes one or several of O, F.

19. The positive electrode paste according to any one of claims 13 to 18, wherein, The volume average particle size D of the positive electrode active particles is 0.5 to 10 μm. v 50 is 0.5 μm to 10 μm.

20. The positive electrode slurry of claim 19, wherein, The volume average particle size D of the positive electrode active particles v 50 is 0.5 to 2 μm.

21. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer comprising positive electrode active particles and the dispersant according to any one of claims 1 to 12.

22. The cathode sheet of Claim 21, wherein, The mass content of the dispersant is 0.3% to 1.1% based on the mass of the positive electrode film layer.

23. The cathode sheet of claim 21 or 22, wherein, The positive electrode active particles comprise olivine-type phosphate active material.

24. A battery comprising the positive electrode sheet according to any one of claims 21 to 23.

25. An electric device comprising the battery according to claim 24.

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