Positive electrode slurry and preparation method thereof, positive electrode plate and battery

Abstract

The invention discloses positive electrode slurry and a preparation method thereof, a positive electrode plate and a battery, and belongs to the technical field of batteries. The positive electrode slurry comprises a positive electrode active component, a conductive agent, a binder and a solvent, the positive electrode slurry also contains an additive; the additive is at least one of humic acid, fulvic acid and humin; and the additive accounts for 0.01-2wt% of the total amount of the positive active component, the conductive agent and the binder. By adding the additive into the positive electrode slurry, on one hand, the high residual alkali characteristic of nickel-rich, lithium-rich and other positive electrode material (NCM, NCA and LMR) systems can be reduced, and the problem of slurry gel is reduced; and on the other hand, a nano conductive agent, nano-scale LFP or LMFP and other system positive electrode materials can be effectively dispersed, the additive has very high thermal stability, and the long cycle performance and high-temperature stability of the battery can be improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a positive electrode slurry and its preparation method, a positive electrode sheet, and a battery. Background Technology

[0002] As lithium-ion batteries become increasingly mature, the performance requirements for battery cells are gradually rising. However, many unresolved issues remain. Among these, the slurry mixing stage, a crucial part of the manufacturing process, presents challenges for materials like lithium iron phosphate (LFP) or lithium iron manganese phosphate (LMFP) with olivine structures, including difficulties in slurry dispersion and stability. For layered nickel-rich cathode materials, such as nickel-cobalt-manganese ternary materials (NCM) and nickel-cobalt-aluminum materials (NCA), layered lithium-rich cathode materials like LMR, and spinel-type cathode materials like lithium manganese oxide (LMO), while these materials exhibit good thermal stability and superior discharge platforms, the problem of residual alkali on the cathode material surface is particularly prominent. The presence of residual alkali, especially during slurry mixing, leads to an increase in the slurry's pH value, triggering a gel effect. This causes a sharp increase in slurry viscosity and reduced fluidity, significantly impacting subsequent coating and battery assembly processes. This phenomenon not only increases production difficulty but can also lead to battery performance instability, particularly affecting cycle life and energy density. Summary of the Invention

[0003] The main objective of this application is to provide a positive electrode slurry and its preparation method, a positive electrode sheet, and a battery, so as to solve the problem that the positive electrode slurry is prone to gelation during the mixing process in the prior art.

[0004] To achieve the above objectives, according to one aspect of this application, a positive electrode slurry is provided, comprising a positive electrode active component, a conductive agent, a binder, and a solvent; the positive electrode slurry further contains an additive; the additive is at least one selected from humic acid, fulvic acid, and humin; the additive is 0.01 to 2 wt% of the total weight of the positive electrode active component, the conductive agent, and the binder.

[0005] Furthermore, the additive is 0.1 to 1 wt% of the total weight of the positive electrode active component, conductive agent and binder.

[0006] Furthermore, the additive is 0.1 to 0.5 wt% of the total weight of the positive electrode active component, conductive agent, and binder.

[0007] Furthermore, the additive is a mixture of humic acid and fulvic acid.

[0008] Further, the weight ratio of humic acid to fulvic acid is 1:(0.1~10000), preferably 1:(0.1~100), and even more preferably 1:(0.1~10).

[0009] Furthermore, the additive is a mixture of humic acid and humin.

[0010] Further, the weight ratio of humic acid to humin is 1:(0.1~10000), preferably 1:(0.1~100), and even more preferably 1:(1~10).

[0011] Furthermore, the additive is a mixture of humin and fulvic acid.

[0012] Furthermore, the weight ratio of humin to fulvic acid is 1:(0.1~10000), preferably 1:(0.1~100), and even more preferably 1:(1~10).

[0013] Furthermore, the additive is a mixture of humic acid, fulvic acid, and humin.

[0014] Further, the weight ratio of humic acid, fulvic acid and humin is 1:(0.1~10000):(0.1~10000), preferably 1:(1~100):(1~100), and even more preferably 1:(1~10):(1~10).

[0015] Further, by weight, the positive electrode slurry comprises: 90-99.4 parts of positive electrode active component, 0.1-4 parts of conductive agent, 0.45-4 parts of binder, and 0.01-2 parts of additives.

[0016] Furthermore, the positive electrode active component is 95-98 parts, the conductive agent is 1-2 parts, the binder is 0.9-2 parts, and the additive is 0.1-1 parts.

[0017] Furthermore, the solid content of the positive electrode slurry is 50-80 wt%, preferably 65-80 wt%.

[0018] Furthermore, the positive electrode active component is selected from LiNi x Co y Mn z T (1-x-y-z) O2, LiCo x’ T (1-x’) O2, LiNi x’’ T' y’ Mn (2-x’’-y’) O4, Li z’ MPO4, aLiNi x Co y Mn z T (1-x-y-z) O2 (1-a)Li₂MnO₃ and NaNi 1 / 3 Co 1 / 3 Mn 1 / 3At least one of O2; wherein T is at least one of Ti, Mg, Al, Ca, Sr, Zr, Si and Fe; 0≤x≤1, 0≤y≤1, 0≤z≤1, 0<x+y+z≤1; 0<x'≤1, 0.3≤x''≤0.6, 0.01≤y'≤0.2, T' is at least one of Ti, Mg, Al, Co, Sr, Fe, Si, Zn, Zr and Ca; 0.5≤z'≤1, M is at least one of Fe, Co and Mn, 0≤a≤1.

[0019] Furthermore, the conductive agent is selected from at least one of acetylene black, carbon black, conductive graphite, carbon fiber, carbon nanotubes, and graphene.

[0020] Furthermore, the adhesive is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, and hydrogenated nitrile rubber.

[0021] Furthermore, the solvent is N-methylpyrrolidone.

[0022] According to the second aspect of this application, a method for preparing the above-mentioned positive electrode slurry is provided: the raw materials are mixed according to the raw material composition ratio to obtain the positive electrode slurry.

[0023] According to a third aspect of this application, a positive electrode sheet is provided, comprising a positive current collector and a positive active coating attached to the surface of the positive current collector; the positive active coating is obtained by drying the positive electrode slurry obtained by the above-mentioned positive electrode slurry preparation method.

[0024] According to a fourth aspect of this application, a battery is provided, comprising a positive electrode, a negative electrode, a separator, and an electrolyte; the positive electrode is the aforementioned positive electrode.

[0025] Compared with the prior art, this application has the following beneficial effects:

[0026] This application provides a positive electrode slurry containing a specific additive. This additive possesses suitable weak acidity, which reduces the high residual alkali characteristics of nickel-rich materials, minimizes slurry gelation problems, and achieves excellent degelation effects. It can also effectively disperse conductive agents and nano-sized LFP or LMFP materials, resulting in excellent dispersion. This additive exhibits very high thermal stability, unlike traditional dispersants which suffer from high-temperature instability. This material is also effective against Ni... 2+ Ni 3+ Co 3+ Fe 2+ Fe 3+ Mn 2+ Mn 3+Transition metal ions have strong specific adsorption and binding effects, which can significantly improve the dissolution of transition metals on the positive electrode side, reduce damage to the SEI of the negative electrode, electrolyte consumption and gas generation, and greatly improve the cycle performance of the cell. The additive is inexpensive and can reduce the manufacturing cost of the cell. Moreover, the above substances are simply added during the slurry mixing process, which is fully compatible with existing lithium-ion battery production processes. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0028] As mentioned in the background technology, positive electrode materials are prone to problems such as gelation, agglomeration, difficulty in dispersion, and unstable viscosity rebound during the slurry mixing process; and the dissolution of transition metals is inevitable, which leads to problems such as damage to the negative electrode SEI, electrolyte consumption, and gas generation, thereby seriously affecting the long cycle performance and high temperature performance of the battery.

[0029] According to one aspect of this application, a positive electrode slurry is provided, comprising a positive electrode active component, a conductive agent, a binder, and a solvent; the positive electrode slurry further contains an additive; the additive is at least one selected from humic acid, fulvic acid, and humin; the additive is 0.01 to 2 wt% of the total weight of the positive electrode active component, the conductive agent, and the binder.

[0030] The additives mentioned above in this application are added in any value or a range between any two of the following: 0.01wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, and 2.0wt%.

[0031] Of the three additives selected in this application, humic acid has a relatively large molecular structure containing carboxyl, phenolic, and alcoholic hydroxyl groups. It exhibits good dispersibility and adsorption capacity, improving the dispersibility of the cathode slurry, reducing residual alkalinity, and enhancing thermal stability, thus contributing to improved long-cycle characteristics and high-temperature performance of the battery. Fulvic acid has a smaller molecular size and good water solubility and dispersibility, helping to improve the gelation phenomenon of the cathode slurry and enhance battery cycle performance and safety. Huminin has the largest molecular weight and high thermal stability, contributing to the long-cycle and high-temperature performance of the battery.

[0032] This application utilizes the weak acidity of humic acid, fulvic acid, or humin in the cathode slurry to reduce the high residual alkali characteristics of nickel-rich materials, thereby minimizing slurry gelation and achieving excellent degelation effects. Furthermore, its dispersibility effectively disperses conductive agents and nano-sized LFP or LMFP materials, resulting in excellent dispersion. These materials possess very high adsorption and thermal stability, and their adhesion to Ni... 2+ Ni 3+ Co 3+ Fe 2+ Fe 3+ Mn 2+ Mn 3+ Transition metal ions have strong specific adsorption and binding effects, which can significantly improve the dissolution of transition metals on the positive electrode side, reduce damage to the SEI of the negative electrode, electrolyte consumption, and gas generation, and greatly improve the cycle performance of the cell. Controlling the amount of additives to 0.01~2wt% can allow for appropriate neutralization with residual alkali, effectively reducing the amount of residual alkali. This specific amount of additive helps to form a stable dispersion system, ensuring uniform dispersion of each component, which can appropriately improve the electrochemical performance of the battery and promote its long cycle characteristics and high-temperature performance.

[0033] To improve the removal effect of additives on residual alkali, the content of additives can be further optimized. In some embodiments, the additive is 0.1 to 1 wt% of the total weight of the positive electrode active component, conductive agent, and binder; for example, 0.1 to 0.5 wt%, and further, 0.1 to 0.3 wt%. Controlling the amount added within the above-mentioned more suitable range can effectively neutralize the residual alkali in the positive electrode, improve dispersibility and thermal stability, and benefit the battery's long cycle life and high-temperature performance.

[0034] The three additives mentioned above each have unique properties and different advantages, and their combined use has a better improvement effect. In some embodiments, the additives are humic acid and fulvic acid, with a weight ratio of 1:(0.1~10000); further, 1:(1~100); even further, 1:(1~10), preferably 1:(1~5), even more preferably 1:(1~3), specifically 1:1; or, the additive is a mixture of humic acid and humin, with a weight ratio of 1:(0.1~10000); further, 1:(1~100); even further, 1:(1~10), preferably 1:(1~5), even more preferably 1:(1~3), specifically 1:1; or, the additive is humic acid... A mixture of humic acid and fulvic acid; the weight ratio of the two is 1:(0.1~10000); further, 1:(1~100); even further, 1:(1~10), preferably 1:(1~5), even more preferably 1:(1~3), specifically 1:1; or, the additive is a mixture of humic acid, fulvic acid and humin; the weight ratio of humic acid, fulvic acid and humin is 1:(0.1~10000):(0.1~10000), further, 1:(1~100):(1~100), even further, 1:(1~10):(1~10); preferably 1:(1~5):(1~5), even more preferably 1:(1~3):(1~3), specifically 1:1:1. Using the above two or three in combination allows each to exert its own advantages, resulting in a better synergistic effect in removing residual alkali, improving dispersibility, high-temperature stability, and reducing metal leaching.

[0035] When using additives to reduce residual alkali, eliminate gelation, and improve dispersibility and stability, it is also necessary to ensure that the positive electrode slurry has good electrochemical performance, such as capacity, conductivity, and adhesion, as well as good compatibility with the additives, thereby optimizing the component ratio of the positive electrode slurry. In some specific embodiments, the positive electrode slurry comprises, by weight, 90-99.4 parts of positive electrode active component, 0.1-4 parts of conductive agent, 0.45-4 parts of binder, and 0.01-2 parts of additive; wherein, the active component can be any value from 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 parts or any range between two; the conductive agent is 0.1, 0... The amounts of the following components are specified: 0.5, 1, 2, 3, 4, or any value between any two; the binder is specified: 0.45, 0.5, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, or any value between any two; the additives are specified: 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 parts, or any value between any two; the solid content of the positive electrode slurry is 50-80 wt%, more preferably 65-80 wt%, and most preferably 70-78 wt%. Using the above slurry formulation and solid content ensures that the slurry has suitable viscosity, dispersibility, and high-temperature stability while maintaining good electrochemical performance.

[0036] The above-mentioned additives are suitable for specific positive electrode active materials, such as lithium batteries and sodium batteries; in some embodiments, the positive electrode active component is selected from LiNi. x Co y Mn z T (1-x-y-z) O2, LiCo x’ T (1-x’) O2, LiNi x’’ T' y’ Mn (2-x’’-y’) O4, Li z’ MPO4, aLiNi x Co y Mn z T (1-x-y-z) O2 (1-a)Li2MnO3( (representing composite) and NaNi 1 / 3 Co 1 / 3 Mn 1 / 3At least one of O2; wherein T is at least one of Ti, Mg, Al, Ca, Sr, Zr, Si, and Fe; 0≤x≤1, 0≤y≤1, 0≤z≤1, 0<x+y+z≤1; 0<x'≤1, 0.3≤x''≤0.6, 0.01≤y'≤0.2, T' is at least one of Ti, Mg, Al, Co, Sr, Fe, Si, Zn, Zr, and Ca; 0.5≤z'≤1, M is at least one of Fe, Co, and Mn, 0≤a≤1. The humic acid, fulvic acid, and humin selected in this application as positive electrode slurry additives can significantly reduce the residual alkali of the above-mentioned positive electrode active materials, thereby improving the gelation and agglomeration phenomena that occur during the slurry mixing process, enhancing the slurry dispersibility, and promoting the long cycle life and high-temperature stability of the battery.

[0037] According to a second aspect of this application, a method for preparing the above-mentioned positive electrode slurry is provided, comprising: mixing the raw materials according to the raw material composition ratio to obtain the above-mentioned positive electrode slurry.

[0038] According to a third aspect of this application, a positive electrode sheet is provided, which includes a current collector and a positive active coating attached to the surface of the current collector; the positive active coating is obtained by drying the positive electrode slurry or the positive electrode slurry prepared by the above-mentioned positive electrode slurry preparation method; for example, the positive electrode sheet is a lithium battery positive electrode sheet or a sodium battery positive electrode sheet.

[0039] According to a fourth aspect of this application, a battery is provided, comprising a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode is the aforementioned positive electrode; for example, the battery is a lithium battery or a sodium battery.

[0040] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0041] The raw materials used in the following embodiments of this application are sourced as follows:

[0042] Humic acid, sourced from Shanghai Aladdin Biochemical Technology Co., Ltd., has a purity of ≥98% and a chemical structure as shown in Formula I.

[0043] Fulvic acid, derived from Caymanchem in the United States, has a purity of ≥98% and a chemical structure as shown in Formula II.

[0044] Huminsu is sourced from Sigma-Aldrich.

[0045] Formula I; Formula II.

[0046] Example 1

[0047] LiNi 0.65 Co0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 96.8 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, 0.2 parts humic acid, and N-methylpyrrolidone, controlling the solid content to be 76 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0048] Example 2

[0049] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 99.2 parts of O2, 0.1 parts of acetylene black, 0.5 parts of polytetrafluoroethylene, 0.2 parts of humic acid, and N-methylpyrrolidone, controlling the solid content to be 71.8 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0050] Example 3

[0051] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 1.8 parts of O2, 4 parts of acetylene black, 4 parts of polytetrafluoroethylene, 0.2 parts of humic acid, and N-methylpyrrolidone, controlling the solid content to 74.5 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0052] Example 4

[0053] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 96.99 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, 0.01 parts humic acid, and N-methylpyrrolidone, controlling the solid content to be 73.3 wt%. 0.65 Co0.08 Mn 0.27 O2 positive electrode slurry.

[0054] Example 5

[0055] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 95 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, 2 parts humic acid, and N-methylpyrrolidone, controlling the solid content to 73.3 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0056] Example 6

[0057] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 96.5 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, 0.5 parts humic acid, and N-methylpyrrolidone, controlling the solid content to be 73.3 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0058] Example 7

[0059] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 96 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, 1 part humic acid, and N-methylpyrrolidone, controlling the solid content to 73.3 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0060] Example 8

[0061] The difference between Example 8 and Example 1 is that humic acid is replaced with 0.2 parts of humin.

[0062] Example 9

[0063] The difference between Example 9 and Example 1 is that humic acid is replaced with 0.2 parts of fulvic acid.

[0064] Example 10

[0065] The difference between Example 10 and Example 1 is that humic acid is replaced with a mixture of 0.1 parts humic acid and 0.1 parts fulvic acid.

[0066] Example 11

[0067] The difference between Example 11 and Example 1 is that humic acid is replaced with a mixture of 0.02 parts humic acid and 0.18 parts fulvic acid.

[0068] Example 12

[0069] The difference between Example 12 and Example 1 is that humic acid is replaced with a mixture of 0.18 parts humic acid and 0.02 parts fulvic acid.

[0070] Example 13

[0071] The difference between Example 13 and Example 1 is that humic acid is replaced with a mixture of 0.1 parts humic acid and 0.1 parts humin.

[0072] Example 14

[0073] The difference between Example 14 and Example 1 is that humic acid is replaced with a mixture of 0.02 parts humic acid and 0.18 parts humin.

[0074] Example 15

[0075] The difference between Example 15 and Example 1 is that humic acid is replaced with a mixture of 0.18 parts humic acid and 0.02 parts humin.

[0076] Example 16

[0077] The difference between Example 16 and Example 1 is that humic acid is replaced with a mixture of 0.1 parts humin and 0.1 parts fulvic acid.

[0078] Example 17

[0079] The difference between Example 17 and Example 1 is that humic acid is replaced with a mixture of 0.02 parts humin and 0.18 parts fulvic acid.

[0080] Example 18

[0081] The difference between Example 18 and Example 1 is that humic acid is replaced with a mixture of 0.18 parts humin and 0.02 parts fulvic acid.

[0082] Example 19

[0083] The difference between Example 19 and Example 1 is that humic acid is replaced with humic acid, fulvic acid and humin, with a total weight of 0.2 parts and a weight ratio of 1:1:1.

[0084] Example 20

[0085] The difference between Example 20 and Example 7 is that humic acid is replaced with humic acid, fulvic acid and humin, with a total weight of 1 part and a weight ratio of 1:10:10.

[0086] Example 21

[0087] The difference between Example 21 and Example 7 is that humic acid is replaced with humic acid, fulvic acid and humin, with a total weight of 1 part and a weight ratio of 10:1:1.

[0088] Example 22

[0089] The difference between Example 22 and Example 1 is that LiNi is used. 0.65 Co 0.08 Mn 0.27 O2 replaced with LiMn 0.5 Fe 0.5 PO4.

[0090] Example 23

[0091] The difference between Example 23 and Example 1 is that LiNi is used. 0.65 Co 0.08 Mn 0.27 O2 replaced with LiNi 0.78 Co 0.1 Mn 0.12 O2.

[0092] Example 24

[0093] The difference between Example 24 and Example 1 is that LiNi is used. 0.65 Co 0.08 Mn 0.27 O2 is replaced with Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 O2.

[0094] Example 25

[0095] The difference between Example 25 and Example 1 is that LiNi is used. 0.65 Co 0.08 Mn 0.27 O2 was replaced with LiCoO2.

[0096] Example 26

[0097] The difference between Example 26 and Example 1 is that LiNi is used. 0.65 Co 0.08 Mn 0.27 O2 is replaced with NaNi 1 / 3 Co 1 / 3Mn 1 / 3 O2.

[0098] Comparative Example 1

[0099] The difference between Comparative Example 1 and Example 1 is that the positive electrode slurry contains no additives;

[0100] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry formulation: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 97 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, and N-methylpyrrolidone, controlling the solid content to be 72 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0101] Comparative Example 2

[0102] The difference between Comparative Example 2 and Example 1 is that the amount of humic acid added was replaced with 3 parts;

[0103] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry formulation: by weight, LiNi 0.65 Co 0.08 Mn 0.27 LiNi was obtained by mixing 94 parts O2, 1.5 parts carbon black, 1.5 parts polyvinylidene fluoride, 3 parts humic acid, and N-methylpyrrolidone, controlling the solid content to be 72 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0104] Comparative Example 3

[0105] The difference between Comparative Example 3 and Example 1 is that humic acid was replaced with oxalic acid (H2C2O4).

[0106] LiNi 0.65 Co 0.08 Mn 0.27 O2 cathode slurry formulation: by weight, LiNi 0.65 Co0.08 Mn 0.27 LiNi was obtained by mixing 96.8 parts of O2, 1.5 parts of carbon black, 1.5 parts of polyvinylidene fluoride, 0.2 parts of oxalic acid, and N-methylpyrrolidone, controlling the solid content to 72 wt%. 0.65 Co 0.08 Mn 0.27 O2 positive electrode slurry.

[0107] Performance testing:

[0108] The viscosity of the positive electrode slurry prepared in each embodiment and comparative example was measured, and the results are shown in Table 1.

[0109] Test method: Refer to standard 20240765-T-610, use a rotational viscometer to test the viscosity of the slurry at 0h, 6h, 12h, 18h and 24h, the unit is mpa.s.

[0110] Table 1

[0111]

[0112] Table 1 shows that, due to the addition of at least one of humic acid, fulvic acid and humin in the positive electrode slurry of each embodiment of this application, agglomeration and gelation phenomena are reduced during slurry mixing, and dispersibility is improved. The initial viscosity of the slurry is mainly concentrated in 5000~6000 mPa·s, which is suitable for positive electrode sheets and lithium batteries or sodium batteries, and can promote long cycle performance and high temperature stability.

[0113] Comparative Example 1, without any additives, achieved an initial viscosity of 8500 mPa·s. Comparative Example 2, although containing humic acid, had an excessive amount, resulting in an initial viscosity of 4500 mPa·s. Comparative Example 3, containing oxalic acid, while having the effect of eliminating residual alkali, showed little effect, with an initial viscosity of 7800 mPa·s. These results demonstrate that the embodiments of this application selected more suitable additives and controlled the dosage appropriately to significantly reduce the viscosity of the slurry.

[0114] The cathode slurry of this application incorporates additives. These additives possess a certain degree of weak acidity, which reduces the high residual alkali characteristics of nickel-rich materials, minimizes slurry gelation, and achieves excellent degelation effects. They also effectively disperse conductive agents and nano-sized LFP or LMFP materials, resulting in excellent dispersion. Furthermore, these additives exhibit very high thermal stability, unlike traditional dispersants which suffer from high-temperature instability. The materials also exhibit good Fe... 2+ Mn 2+Transition metal ions have strong specific adsorption and binding effects, which can significantly improve the dissolution of transition metals on the positive electrode side, reduce damage to the SEI of the negative electrode, electrolyte consumption and gas generation, and greatly improve the cycle performance of the cell. Moreover, the three materials selected are inexpensive, which can reduce the manufacturing cost of the cell. Furthermore, the process of simply adding the above substances during the slurry mixing process is fully compatible with existing lithium-ion battery production processes.

[0115] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0116] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A positive electrode slurry, comprising a positive electrode active component, a conductive agent, a binder, and a solvent; characterized in that, The positive electrode slurry also contains additives; the additives are at least one of humic acid, fulvic acid and humin; the additives are 0.01~2 wt% of the total weight of the positive electrode active component, the conductive agent and the binder.

2. The positive electrode slurry according to claim 1, characterized in that, The additive is 0.1 to 1 wt% of the total weight of the positive electrode active component, the conductive agent, and the binder.

3. The positive electrode slurry according to claim 1, characterized in that, The additive is 0.1 to 0.5 wt% of the total weight of the positive electrode active component, the conductive agent, and the binder.

4. The positive electrode slurry according to any one of claims 1 to 3, characterized in that, The additive is a mixture of humic acid and fulvic acid; preferably, the weight ratio of humic acid to fulvic acid is 1:(0.1~10000), more preferably 1:(0.1~100), and even more preferably 1:(0.1~10). Alternatively, the additive is a mixture of humic acid and humin; preferably, the weight ratio of humic acid to humin is 1:(0.1~10000), more preferably 1:(0.1~100), and even more preferably 1:(1~10). Alternatively, the additive is a mixture of humin and fulvic acid; preferably, the weight ratio of humin to fulvic acid is 1:(0.1~10000), more preferably 1:(0.1~100), and even more preferably 1:(1~10).

5. The positive electrode slurry according to any one of claims 1 to 3, characterized in that, The additive is a mixture of the humic acid, the fulvic acid, and the humin; Preferably, the weight ratio of humic acid, fulvic acid and humin is 1:(0.1~10000):(0.1~10000), more preferably 1:(1~100):(1~100), and even more preferably 1:(1~10):(1~10).

6. The positive electrode slurry according to any one of claims 1 to 5, characterized in that, By weight, the positive electrode slurry comprises: 90-99.4 parts of the positive electrode active component, 0.1-4 parts of the conductive agent, 0.45-4 parts of the binder, and 0.01-2 parts of the additive; preferably, the positive electrode active component comprises 95-98 parts, the conductive agent comprises 1-2 parts, the binder comprises 0.9-2 parts, and the additive comprises 0.1-1 parts. And / or, the solid content of the positive electrode slurry is 50-80 wt%, preferably 65-80 wt%.

7. The positive electrode slurry according to any one of claims 1 to 6, characterized in that, The positive electrode active component is selected from LiNi x Co y Mn z T (1-x-y-z) O2, LiCo x’ T (1-x’) O2, LiNi x’’ T' y’ Mn (2-x’’-y’) O4, Li z’ MPO4, aLiNi x Co y Mn z T (1-x-y-z) O2 (1-a)Li₂MnO₃ and NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 At least one of O2; wherein T is at least one of Ti, Mg, Al, Ca, Sr, Zr, Si and Fe; 0≤x≤1, 0≤y≤1, 0≤z≤1, 0<x+y+z≤1; 0<x'≤1, 0.3≤x''≤0.6, 0.01≤y'≤0.2, T' is at least one of Ti, Mg, Al, Co, Sr, Fe, Si, Zn, Zr and Ca; 0.5≤z'≤1, M is at least one of Fe, Co and Mn, 0≤a≤1; And / or, the conductive agent is selected from at least one of acetylene black, carbon black, conductive graphite, carbon fiber, carbon nanotubes and graphene; And / or, the adhesive is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, and hydrogenated nitrile rubber; And / or, the solvent is N-methylpyrrolidone.

8. A method for preparing a positive electrode slurry according to any one of claims 1 to 7, characterized in that, According to the raw material grouping ratio, the raw materials are mixed into a slurry to obtain the positive electrode slurry.

9. A positive electrode sheet, comprising a positive current collector and a positive active coating adhered to the surface of the positive current collector; characterized in that, The positive electrode active coating is obtained by drying the positive electrode slurry prepared by any one of claims 1 to 7 or the positive electrode slurry prepared by the method of claim 8.

10. A battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte; characterized in that, The positive electrode is the positive electrode as described in claim 9.

Images