Dispersion of carbon nanotubes and carbon black

Abstract

The present invention relates to conductive dispersions having advantageous characteristics comprising carbon black particles and carbon nanotube particles having carefully selected characteristics, such as surface area, oil absorption (OAN), ratio of cOAN / OAN, number of primary particles per aggregate, D50 length, or outer diameter. The optimized dispersions according to the invention are characterized by improved stability and suitable rheological properties and enable the formation of improved lithium ion batteries.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to stable dispersions comprising carbon nanotube particles and carbon black particles in a dispersion medium with advantageous stability and rheological properties. In the present disclosure, guidelines for selecting suitable carbon black particles and carbon nanotube particles to achieve stable dispersions with improved rheological properties are provided. Carbon blacks can be selected, for example, based on their respective Braun-Emmett-Teller theoretical specific surface area (BET SSA), their oil absorption number (OAN), their compressed oil absorption number (cOAN), their cOAN / OAN ratio, their primary particles per aggregate, and / or their degree of branching. Carbon nanotubes can be selected, for example, based on their respective BET SSA, nanotube length, and outer diameter. Such advantageous dispersions of carbon black particles and carbon nanotube particles can be used for various applications such as in lithium ion battery manufacturing.

[0002] Further provided herein are cathode slurries, cathodes, and Li-ion batteries comprising or formed from the stable dispersions as conductive additives. Moreover, methods of obtaining stable and advantageous dispersions from mixtures of carbon black and carbon nanotubes are disclosed. BACKGROUND

[0003] Carbon nanotubes (CNTs) are a class of one-dimensional electrically conductive carbon structures. Carbon nanotubes show desirable physical properties such as high mechanical strength and high electrical conductivity. Typically, carbon nanotubes are commercially mainly sold in the form of dispersions and have diameters ranging from 2 nm to about 50 nm and lengths ranging from several micrometers to several tens of micrometers. Currently, the largest field of application for carbon nanotubes is the use of CNTs as conductive additives in, for example, lithium ion (Li-Ion) battery electrodes.

[0004] However, due to their high specific surface energy and other surface properties, carbon nanotubes are generally prone to agglomeration and thus tend to show disadvantageous dispersion properties. Currently, high-energy ball milling and dispersants are required to obtain CNT dispersions with acceptable stability. Furthermore, the viscosity of the CNT dispersions must often be adjusted to allow sufficient processability and subsequent suitability in industrial applications.

[0005] To achieve the required viscosity and dispersion stability, the solids content of the CNT dispersions is often adjusted with added organic additives. Conductive carbon black, an isotropically conductive carbon material also used in lithium ion batteries, can be used to increase the dispersibility of carbon nanotubes while producing beneficial effects on the dispersion viscosity and stability. Stable and easy-to-handle dispersions are highly desirable during the industrial manufacturing of lithium ion batteries.

[0006] It has now been found that a combination of conductive carbon black and carbon nanotubes as conductive additives in a dispersion not only shows advantageous dispersion characteristics but also leads to improved battery performance. Such dispersions enable the production of higher quality electrodes for lithium ion batteries due to the improved ease of handling and processability of the electrode slurry during manufacturing resulting from the combination of carbon black and carbon nanotubes dispersions. However, due to the general properties of carbon black, the rheological behavior of the resulting dispersion will be greatly influenced by the properties of the carbon black particles employed when producing a hybrid dispersion. Therefore, a careful selection of the appropriate carbon black particles and carbon nanotube particles is required to obtain an optimized dispersion and an easily handled electrode slurry for lithium ion battery applications.

[0007] For example, patent application CN 106711453 A describes a conductive carbon slurry as cathode material comprising both carbon nanotubes and conductive carbon black. Similarly, CN 104766978 B discloses a method for preparing a conductive carbon paste comprising carbon nanotubes, carbon black and a binder in specific proportions. Meanwhile, CN 104868125 B describes a method for preparing a carbon nanotube and carbon black dispersion by grinding the carbon nanotubes in a zirconium bead mill prior to dispersion with carbon black.

[0008] In view of the above, there is a need for an optimized dispersion comprising carbon black and carbon nanotubes that modulates rheological parameters like viscosity and yield stress as well as dispersion stability while maximizing carbon loading. Therefore, it is an object of the present invention to identify specific parameters of carbon black and carbon nanotubes that enable the formulation of advantageous dispersions featuring a high total amount of carbonaceous particulate material while having an acceptable viscosity, good dispersion stability and showing advantageous damping behavior. SUMMARY

[0009] The inventors surprisingly found that the rheological behavior of a dispersion comprising both carbon black and carbon nanotubes is greatly influenced by the careful selection of the appropriate carbon black based on certain physical parameters. Therefore, the present invention provides tailored stable dispersions to the required viscosity range while also showing a relatively high concentration of carbon nanotube and conductive carbon black particles. Herein, the dispersions according to the present invention show enhanced process feasibility and stability characteristics which are particularly advantageous for use as conductive additives in lithium ion battery (LIB) manufacturing.

[0010] Thus, the inventors have found that a carefully selected combination of carbon black (CB) particles and carbon nanotube (CNT) particles and the adjustment of their respective ratios results in a dispersion that not only greatly increases the ease of the production process, but also enables the manufacture of higher quality electrodes with improved properties, thereby further advancing battery technology.

[0011] Thus, in a first aspect, the present invention relates to a dispersion comprising carbon black (CB) particles, wherein the carbon black particles are characterized by a BET SSA of about 40 m 2 / g to about 650 m 2 / g, an oil absorption number (OAN) of about 230 mL / 100 g to about 400 mL / 100 g, a compressed oil absorption number (cOAN) to OAN ratio (cOAN / OAN) of about 0.2 to about 0.85, and less than about 235 primary particles per aggregate. Furthermore, the dispersion according to the first aspect comprises carbon nanotube (CNT) particles, wherein the carbon nanotube particles are characterized by an outer diameter of about 9 nm to about 18 nm and a D 50 length of about 1 pm to about 13 pm. The dispersion of the present invention as described above comprises a dispersion medium, and the carbon black particles and the carbon nanotube particles are present in a weight ratio of CNT particles to CB particles of about 10 : 1 to about 1 : 1.

[0012] In a second aspect, the present invention relates to a cathode slurry composition comprising the dispersion according to the first aspect of the present invention, an active lithium material, a dispersion medium, and a binder.

[0013] Furthermore, in a third aspect of the present invention, a cathode produced by applying the electrode slurry of the second aspect of the present invention to a substrate and subsequently drying the coated substrate at a temperature of at least 100 °C for 5 minutes is described.

[0014] Furthermore, in a fourth aspect of the present invention, the present invention describes a lithium-ion (Li-Ion) battery using the dispersion according to the first aspect of the present invention in the manufacturing process. Furthermore, such a battery comprises a cathode according to the third aspect of the present invention and shows improved properties such as, for example, direct contact resistance, discharge rate, and / or capacity retention after prolonged storage.

[0015] In a fifth and last aspect of the present application, a method of forming a stable dispersion comprising CNT particles and CB particles in a ratio of about 10: 1 (w / w) to about 1 : 1 (w / w) is described. In a first step of the method, a dispersant is dispersed in a dispersion medium. Then, carbon black particles are added to the mixture of dispersion medium / dispersant, wherein the carbon black particles to be used in the method are characterized by a BET SSA of about 40 m 2 / g to about 650 m 2 / g, an oil absorption number (OAN) of about 230 mL / 100 g to about 400 mL / 100 g, a ratio of the compressed oil absorption number (cOAN) to the OAN of about 0.2 to about 0.85, and less than about 235 primary particles per aggregate. In a third step, carbon nanotube particles are added to the resulting mixture, wherein the CNT particles to be used in the method are characterized by an outer diameter of about 9 nm to about 18 nm, and a D 50 length of about 1 μιη to about 13 μιη. Finally, the mixture comprising dispersion medium / dispersant / CB particles / CNT particles is processed in a mill until a dispersion is obtained. Optionally, the dispersion obtained by the method of the fifth aspect of the present application is characterized by a total amount of carbonaceous particulate material (referring to the sum of CB particles and CNT particles) of about 1.5 wt% to about 10 wt% relative to the total weight of the final dispersion, a viscosity of about 1.0 Pa s to about 6.8 Pa s at a shear rate of 1 Hz when tested by Modular Compact Rheometer, and / or a yield stress of at least about 1.0 Pa and at most 26.0 Pa, the yield stress being defined as the cross-over point of G' and G". BRIEF DESCRIPTION OF DRAWINGS

[0016] The present disclosure will be more fully understood when the following detailed description is considered in connection with the following drawings, in which: Figure 1A DMA analysis of CB dispersions CB1-CB3 containing various carbon blacks and no CNTs is shown. Figure 1B DMA analysis of comparative CB dispersions cCB1-cCB3 containing various carbon blacks and no CNTs is depicted. A plot of the storage modulus G' and the loss modulus G" of each dispersion versus the applied shear stress is plotted.

[0017] Figure 2A Tan(5) of CB dispersions CB1-CB3 containing various carbon blacks and no CNTs is shown. Figure 2BThe tan(5) of comparative CB dispersions cCB1-cCB3 containing various carbon blacks and no CNTs is shown. A plot of the loss factor tan(5) versus applied shear stress is plotted for each dispersion.

[0018] Figure 3A-1 The rheological properties of dispersions IE 1-IE 3 of the invention, which are blends of various carbon blacks and CNT 1 with a CNT solids content of 4.1 wt%, are shown. Figure 3A-2 The rheological properties of comparative dispersions CE 1-CE 3, which are blends of various comparative carbon blacks and CNT 1 with a CNT solids content of 4 to 4.1 wt%, are shown. Figure 3B The rheological properties of dispersions IE 4 and IE 5 of the invention, which are blends of various carbon blacks and CNT 1 according to the invention with a CNT solids content of 5 wt%, and a comparative CNT dispersion cCNT 1 containing only CNT 1 without carbon black and with a CNT solids content of 5 wt%, are shown. Figure 3C-1 The rheological properties of dispersions IE 6-IE 8 of the invention, which are blends of various carbon blacks and CNT 2 according to the invention with a CNT solids content of 2.5 wt%, are shown. Figure 3C-2 The rheological properties of comparative dispersions CE 4-CE 6, which are blends of various comparative carbon blacks and CNT 2 with a CNT solids content of 2.5 wt%, are shown. A plot of the viscosity versus applied shear rate is plotted for each dispersion.

[0019] Figure 4A DMA analysis of dispersions IE 1-IE 3 with a CNT solids content of 4.1 wt% is shown. Figure 4B DMA analysis of dispersions CE 1-CE 3 with a CNT solids content of 4 to 4.1 wt% is shown. A plot of the storage modulus G’ and loss modulus G” versus applied shear stress is plotted for each dispersion.

[0020] Figure 5 DMA analysis of dispersions IE 4 and IE 5 and CNT dispersion cCNT 1, each with a CNT solids content of 5 wt%, is shown. A plot of the storage modulus G’ and loss modulus G” versus applied shear stress is plotted for each dispersion.

[0021] Figure 6A DMA analysis of dispersions IE 6-IE 8 with a CNT solids content of 2.5 wt% is shown. Figure 6BDMA analysis of dispersions CE 4 to CE 6 with a CNT solids content of 2.5 wt% is shown. A plot of the storage modulus G' and the loss modulus G" of each dispersion against the applied shear stress is plotted.

[0022] Figure 7A Tan(5) of dispersions IE 1 to IE 3 with a CNT solids content of 4.1 wt% is shown. Figure 7B Tan(5) of dispersions CE 1 to CE 3 with a CNT solids content of 4 wt% to 4.1 wt% is shown. A plot of the loss factor tan(5) of each dispersion against the applied shear stress is plotted.

[0023] Figure 8 Tan(5) of dispersions IE 4 and IE 5 and CNT dispersion cCNT 1, each with a CNT solids content of 5 wt%, is shown. A plot of the loss factor tan(5) of each dispersion against the applied shear stress is plotted. A plot of the loss factor tan(5) of each dispersion against the applied shear stress is plotted.

[0024] Figure 9A Tan(5) of dispersions IE 6 to IE 8 with a CNT solids content of 2.5 wt% is shown. Figure 9B Tan(5) of dispersions CE 4 to CE 6 with a CNT solids content of 2.5 wt% is shown. A plot of the loss factor tan(5) of each dispersion against the applied shear stress is plotted.

[0025] Figure 10 Dispersion according to the application with a processable viscosity is shown.

[0026] Figure 11 Paste resulting from the preparation of CE 7 with CNT 3 is shown. This thick paste is not suitable for further testing. DETAILED DESCRIPTION

[0027] The inventors have surprisingly found that careful selection of carbon black particles and carbon nanotube particles according to various parameters not only has a profound positive influence on the rheological properties of the resulting dispersions comprising carbonaceous particulate material, but also improves the stability of the dispersions they comprise, as determined by the yield stress and the tan(5) curve progression over the range of applied shear stress. As mentioned above, carbon nanotube particles impart advantageous conductive properties to lithium ion electrodes comprising them. However, CNT particle dispersions are also typically prone to agglomeration and tend to show disadvantageous dispersion characteristics due to their high specific surface area and other surface properties, which subsequently lead to lower quality Li ion electrodes.

[0028] Dispersions comprising a mixture of both CB particles and CNT particles have been reported in the literature that alleviate some of the difficulties encountered with CNT dispersions. However, the present inventors have surprisingly found that dispersions comprising a carefully selected combination of CB particles and CNT particles not only exhibit particularly advantageous stability and viscosity characteristics, but also exhibit improved performance when used as a conductive additive. Thus, this improved dispersion not only greatly increases the ease of handling and processing, but also enables the production of higher quality lithium ion cathodes, which in turn leads to improved manufacture of lithium ion batteries.

[0029] CB and CNT dispersions and downstream products of the present disclosure

[0030] As summarized in the first aspect of the present invention, the present invention is directed to a dispersion comprising carbon black (CB) particles, wherein the carbon black particles are characterized by a Braun-Emmett-Teller specific surface area (BET SSA) of about 40 m 2 / g to about 650 m 2 / g, an oil absorption number (OAN) of about 230 mL / 100 g to about 400 mL / 100 g, a ratio of the compressed oil absorption number (cOAN) to the OAN (cOAN / OAN) of about 0.2 to about 0.85, and less than about 235 primary particles per aggregate. Further, the dispersion comprises carbon nanotube (CNT) particles, wherein the carbon nanotube particles are characterized by an outer diameter of about 9 nm to about 18 nm and a D 50 length of about 1 μιη to about 13 μιη. The dispersion as described above will also include a dispersion medium, and is characterized in that the CNT and CB of the carbon black particles and carbon nanotubes will be present in a ratio of about 10: 1 to about 1 : 1 to each other. As understood by those skilled in the art, a higher ratio of CNT particles will result in advantageous conductive properties, while a higher ratio of CB will generally result in improved dispersion characteristics.

[0031] Thus, among other parameters, the carbon black particles are characterized by their respective Braun-Emmett-Teller specific surface area (BET SSA). Higher BET SSA of the CB particles is generally associated with increased surface energy, higher conductivity of the CB powder, and higher area of interaction between the particle surfaces and between the particle surfaces and the dispersion medium. Thus, it is generally understood that the BET SSA of the carbon black particles will have a profound effect on the parameters of the resulting dispersion. Accordingly, in certain embodiments of the first aspect, the carbon black particles according to the present invention can also be characterized by a BET SSA of about 40 m 2 / g to about 650 m 2 / g, optionally about 50 m 2 / g to about 630 m 2from about 60 m2 / g to about 610 m2 / g 2 from about 60 m2 / g to about 610 m2 / g 2 BET SSA of from about 60 m2 / g to about 610 m2 / g.

[0032] The dispersion includes CB particles characterized by an oil absorption number (OAN). OAN is a measure of the ability of carbon black particles to absorb liquid and is a macroscopic parameter influenced by various (micro / nano-scale) structural properties of the carbon black. In certain embodiments, the CB particles for use in the present application are further characterized by an OAN of from about 240 mL / 100 g to about 380 mL / 100 g, optionally from about 230 mL / 100 g to about 400 mL / 100 g, from about 250 mL / 100 g to about 360 mL / 100 g, or from about 260 mL / 100 g to about 340 mL / 100 g.

[0033] Further, the CB particles can also be characterized by a "compressed" oil absorption number (cOAN), which describes a function of the carbon black particle structure after a compression step. In some embodiments, the CB particles to be used in the present application can be further characterized by a cOAN of from about 80 mL / 100 g to about 270 mL / 100 g, optionally, the CB particles can be characterized by a cOAN of from about 90 mL / 100 g to about 260 mL / 100 g, from about 100 mL / 100 g to about 250 mL / 100 g, or from about 110 mL / 100 g to about 240 mL / 100 g.

[0034] Further, the CB particles to be used in the dispersion according to the present application are characterized by their ratio of cOAN to OAN (cOAN / OAN). The difference between the initial OAN value and the cOAN value of the compressed sample is a parameter reflecting the elasticity of the carbon black structure to the compression force. The CB particles can be further characterized by a cOAN / OAN ratio of from about 0.2 to about 0.85, optionally, from about 0.25 to about 0.825, from about 0.3 to about 0.8, or from about 0.35 to about 0.775. Alternatively, the CB particles have a ratio of cOAN to OAN of less than about 0.77.

[0035] The CB particles to be used in the dispersions of the present application are characterized by the number of primary particles contained in each aggregate. The term "primary particles per aggregate" refers to the arrangement of individual carbon black particles within a larger cluster or aggregate. Primary particles are the smallest discrete units of carbon black, while aggregates are formed when these primary particles come together, often due to covalent bonds between primary particles. These aggregates can then form agglomerates through interparticle forces. Generally, and without wishing to be bound by theory, lower amounts of agglomerates can indicate lower interparticle forces. This can have a knock-on effect on the macroscopic parameters of the CB particles, such as dispersibility or stability in a dispersion. The CB particles to be used in the present application can be suitably characterized as having less than about 235 primary particles per aggregate, optionally wherein the CB particles are characterized by less than about 220 primary particles per aggregate, less than about 200 primary particles per aggregate, or less than about 180 primary particles per aggregate.

[0036] In some embodiments, the CB particles contained in the dispersions can also be characterized by their respective degrees of branching. As is evident from the name, the degree of branching refers to the branching or branching complexity of the internal structural morphology of the carbon black particles. Without wishing to be bound by theory, higher degrees of branching generally result in a more branched internal morphology, which can affect factors such as, for example, BET SSA, porosity, and the ability of the CB particles to form stable dispersions. The CB particles can have a degree of branching of about 7 to about 18, optionally about 8 to about 17, or even 9 to 16. Alternatively, the CB particles can be characterized by a degree of branching of less than 16.

[0037] Additionally or alternatively, in certain embodiments the CB particles can be further defined by their respective Scott densities. The parameter Scott density refers to the density or mass per unit volume of the CB particles. The Scott density of the CB particles contained in the dispersions of the present application can vary from about 0.01 g / cm 3 to about 0.1 g / cm 3 , optionally wherein the CB particles are characterized by a Scott density of about 0.02 g / cm 3 to about 0.09 g / cm 3 , about 0.03 g / cm 3 to about 0.08 g / cm 3 , about 0.04 g / cm 3 to about 0.7 g / cm 3 , or about 0.045 g / cm 3 to about 0.065 g / cm 3 .

[0038] In particular embodiments according to the present application, the CB particles can be selected from thermal black, acetylene black or furnace black, which are different types of amorphous carbon black obtained by incomplete combustion or thermal decomposition of hydrocarbons. Optionally, the thermal black, acetylene black or furnace black suitable for use in the present application can be a lithium-ion battery grade carbon black obtained from a commercial source, or they can be synthesized from a hydrocarbon feedstock. Lithium-ion battery grade carbon black typically has an OAN value within the range as provided herein to provide sufficient electrical conductivity. Carbon black having an OAN value below the range described herein can not provide sufficient electrical conductivity.

[0039] In particular embodiments, the carbon black particles to be used in the dispersion according to the present application are prepared from hydrocarbons having a high degree of aromaticity. The process for preparing the CB particles to be used herein comprises causing the decomposition of gasified hydrocarbons at temperatures between about 1000 °C and about 1600 °C, for example from 1400 to 1500 °C or from 1450 to 1550 °C, in the presence of oxidizing substances such as O2, CO2, H2O or mixtures thereof, by feeding into a reactor thermal oxidative decomposition of hydrocarbons having a high degree of aromaticity, preferably liquid or gaseous, such as coal tar, ethylene tar, catalytic cracker oil, natural gas, heavy fractions of petroleum chemical distillation residues, or mixtures of any of these materials together with substoichiometric amounts of air and / or steam.

[0040] The reaction time in the reactor is typically less than one second up to several seconds, but it will be appreciated that the exact conditions depend on the carbon source as well as the reactor employed for generating the carbon black material.

[0041] The present inventors have found that, despite the presence of a lower amount of CB particles in the final dispersion relative to the CNT particles, the carbon black particles have a significant influence on the overall rheological properties of the resulting dispersion according to the present application. However, the present inventors have found that, in order to obtain a dispersion according to the present application, the CNT particles need to be carefully selected according to defined parameters in addition to the selection of the CB particles.

[0042] Thus, the carbon nanotube particles to be used in the dispersion of the present application are selected by their respective outer diameter. The outer diameter refers to the width or diameter of the outermost layer of the nanotube structure. In some embodiments of the first aspect of the present application, the CNT particles to be used in the present application can be characterized by an outer diameter of about 9 nm to about 18 nm, optionally wherein the CNT particles are characterized by an outer diameter of about 10 nm to about 16 nm.

[0043] The CNT particles to be used in the dispersion according to the present application are further characterized by their D 50 length. As known to the person skilled in the art, the D 50 length refers to the median length of the CNT particles within the dispersion, and typically accompanies the D10 and D 90 Length distribution measurements. Thus, D 10 Length refers to the nanotube length, where 10% of the CNT particles in a given sample have a length equal to or less than this value, similar to D 90 Length, where 90% of the CNT particles in a given sample have a length equal to or less than this value. Outer diameter and D 50 may influence factors such as the electrical conductivity, mechanical strength, BET SSA, and their interaction with other materials of the CNT particles. Together with the first aspect of the present invention, the CNT particles to be used in the present invention can also be characterized by a D 50 Length of about 1 μιη to about 13 μιη, optionally wherein the CNT particles are characterized by a D 50 Length of about 2 μιη to about 11 μιη, or about 3 μιη to about 10 μιη, or about 9 μιη to about 13 μιη.

[0044] In certain embodiments according to the present invention, at least a portion of the CNT particles to be used in the dispersion of the present invention can be multi-walled. Multi-walled CNTs consist of concentric cylinders of carbon atoms, similar to a tube within a tube, forming a carbon nanotube with multiple layers of carbon atoms. In particular embodiments, substantially all of the CNT particles are multi-walled.

[0045] In further embodiments, the dispersion medium comprised in the dispersion can be selected from the group of organic solvents. Organic solvents are typically liquid at room temperature and consist mainly of carbon and hydrogen atoms, but can also contain other atoms such as nitrogen, oxygen or halogen atoms. Common examples of organic solvents include alcohols such as ethanol and methanol, ketones such as acetone and methyl ethyl ketone, ethers such as diethyl ether and tetrahydrofuran, aromatic solvents such as toluene and xylene, amide solvents such as DMF or NMP, chlorinated solvents such as DCM and chloroform, and hydrocarbons such as hexane and heptane. Optionally, the organic solvent to be used as dispersion medium is an amide solvent. In a particularly preferred embodiment, the dispersion medium to be used in the dispersion is N-methyl-2-pyrrolidone (NMP).

[0046] In some embodiments, the dispersion medium according to the present application is characterized in that it can further comprise a dispersant. A dispersant is a compound that aids in the dispersion and stabilization of CB particles and CNT particles in the dispersion medium. The incorporation of a dispersant in the dispersion enhances the dispersibility of the CB particles and CNT particles in the dispersion medium, as well as has a positive impact on the stability of the resulting dispersion by preventing or slowing down particle agglomeration. It is generally accepted that a dispersant allows for better control of the dispersion process of CB particles and CNT particles. Suitably, the dispersant to be used in the dispersion according to the present application can be an organic dispersant. Optionally, the dispersant can be a polymeric organic dispersant. In a particular embodiment of the present application, the dispersant is polyvinylpyrrolidone (PVP).

[0047] In this embodiment, not only the choice but also the concentration of the dispersant should be carefully considered to achieve the optimal dispersion stability and rheological behavior of the dispersion of the present application comprising both CB particles and CNT particles. Thus, in certain embodiments, the dispersion medium comprises the dispersant in an amount of less than about 2 wt%, optionally wherein the dispersant is comprised in the dispersion medium in an amount of less than about 1.8 wt%, or less than about 1.6 wt%, or less than about 1.4 wt%, or less than about 1.2 wt%, or less than about 1.0 wt%.

[0048] Furthermore, the dispersions according to the first aspect of the present application can also be defined by their rheological properties and / or by the total amount of carbon black (as in CB + CNT) particles per unit weight comprised in the dispersion. The rheological properties of the dispersions according to the present application such as viscosity, yield stress, storage modulus, loss modulus or loss factor are typically obtained by oscillatory measurements. In oscillatory measurements, a material is subjected to a sinusoidal stress or strain, and the strain or stress response of the dispersion is measured. Dynamic mechanical analysis (DMA) simultaneously analyzes both the elastic and viscous material response. In this type of experiment, a sinusoidal strain or stress (tension, bending or shear) is applied to the material using an electromotor, while the resulting stress is measured with a force transducer or the resulting strain is measured with a position transducer.

[0049] In oscillatory experiments for determining the rheological parameters of the dispersions according to the present application, the measured stress is separated into in-phase components using a phase shift and the elastic or storage modulus (G') of the material is determined, which is defined as the ratio of the elastic (in-phase) stress to the strain. The storage modulus relates to the ability of the material to store energy elastically. Similarly, the loss modulus (G") of the material is the ratio of the viscous (out-of-phase) component to the stress and relates to the ability of the material to dissipate stress through heat. The storage modulus G' gives information about the amount of structure present in the material. It represents the amount of energy stored in the elastic (as in a non-liquid) structure of the sample. If it is higher than the loss modulus, the material can be considered to be predominantly elastic. The loss modulus G" represents the amount of energy dissipated in the viscous (as in a liquid) part or in the sample.

[0050] The loss factor tan(5), which measures the damping behavior (resistance to disturbances) of the dispersion, is calculated from G" / G' over a certain range of shear stress and can determine the upper limit of the strain-stress stability of the dispersion. When the loss factor approaches 0, the material can be considered to be predominantly elastic, while a material with a tan(5) value between 0 and 1 typically exhibits a viscoelastic behavior, with both elastic and viscous effects present. The tan(5) value is dimensionless and varies over the range of applied shear stress. As in the first measurable point where G', G" and tan(5) values can be measured, the "starting point" also varies and is specific for each dispersion. It has been observed that for dispersions with tan(5) (first value) > 1, the dispersion is unstable. For the dispersions, the tan(5) values reported herein (see Tables 2, 4, 6) are the average from the first measurable data point tan(5) (first value) to the data point tan(5) (first value + 0.05 Pa) to account for the shift within the first reported tan(5) values. The complete tan(5) plot is reported as Figure 2A 、 Figure 2B 、 Figure 7A 、 Figure 7B 、 Figure 8 、 Figure 9A and Figure 9B .

[0051] In a particular embodiment of the present application, the dispersion is characterized in that it has a total amount of CB particles and CNT particles of from about 1.5 wt% to about 10 wt%, a viscosity of from about 1.0 Pa s to about 6.8 Pa s at a shear rate of 1 Hz when tested by a modular compact rheometer, and / or a yield stress of at least about 1.0 Pa and at most 26.0 Pa, the yield stress being defined as the intersection point of the storage modulus G' and the loss modulus G".

[0052] Generally, the described dispersions can be defined by the total amount of carbonaceous particulate material (understood as the amount of CB particles + CNT particles per unit weight). It is apparent that the amount of particulate material in the dispersion has a significant impact on the characteristics of the described dispersion, wherein higher CB particles and CNT particles loadings tend to result in higher viscosity and reduced processability. It is generally considered desirable for a dispersion used as an electrically conductive additive to have the highest possible CB particles and CNT particles loading while still exhibiting at least a processable viscosity (considered acceptable at about 0.1 Pa s and 8.0 Pa s.

[0053] The selection of CB particles and CNT particles, as well as their total amount and their respective amounts to each other (CNT : CB ratio of about 10 : 1 to about 1 : 1 with respect to their weight) will have a profound impact on the viscosity of the resulting dispersion. Accordingly, in some embodiments, the dispersion can be characterized by its viscosity, which describes the resistance to flow exhibited by the dispersion. In such embodiments, the viscosity of the dispersion is measured using the Modular Compact Rheometer at a measured value obtained at a shear rate of 1 Hz. Therein, the dispersion can be characterized by a viscosity of about 1.2 Pa s to about 6.6 Pa s at a shear rate of 1 Hz. Optionally, the dispersion can be characterized by a viscosity of about 1.4 Pa s to about 6.4 Pa s at a shear rate of 1 Hz.

[0054] The dispersion comprising CB particles and CNT particles according to the present application can also be defined by its yield stress, which is defined by the cross-over point of the storage modulus G' and the loss modulus G". The storage modulus and the loss modulus are obtained by oscillatory measurements as described above by the Modular Compact Rheometer. A lower yield stress means that the dispersion flows and deforms more easily under applied stress, which tends to be beneficial for applications of interest where ease of processing, flowability and processability are desired. Accordingly, in several embodiments, the dispersion of the present application can be defined by a yield stress of at least about 1.2 Pa and at most about 24.0 Pa. Alternatively, the dispersion can be characterized by a yield stress of at least about 1.5 Pa to at most about 22.0 Pa.

[0055] Further, in some embodiments, the dispersion is further characterized by the progression of their storage modulus G' and loss modulus G" over a range of applied shear stress, in Pa. For example, the dispersion can be characterized by a loss modulus (G") in the range of about 0.5 Pa to about 50 Pa and a storage modulus (G') in the range of about 0.5 Pa to about 150 Pa at a shear stress in the range of about 0.001 Pa to about 2 Pa, when tested by a Modular Compact Rheometer. The dispersion can also be characterized by a loss modulus (G") in the range of about 1 Pa to about 45 Pa and a storage modulus (G') in the range of about 1 Pa to about 140 Pa, or a loss modulus (G") in the range of about 2 Pa to about 40 Pa and a storage modulus (G') in the range of about 2 Pa to about 130 Pa at a shear stress in the range of about 0.001 Pa to about 2 Pa, when tested by a Modular Compact Rheometer.

[0056] Finally, the dispersion can additionally or alternatively be defined by its respective loss factor tan (5). The loss factor is a parameter that can suitably indicate the energy dissipation and viscosity of the dispersion under applied shear stress. Thus, a high (higher) loss factor indicates a higher degree of energy dissipation and viscosity in the dispersion under a range of applied shear stress, while a lower loss factor indicates a lower level of energy dissipation and viscosity under shear stress. This is beneficial in applications where controlled or inhibited flow, high stability, and reduced settling are desired. Conversely, a low (lower) tan (5) indicates improved flowability and reduced resistance to deformation, which is ideal in applications requiring easy processing and enhanced processability. Thus, the dispersion used as the conductive additive desirably exhibits a moderate (such as about 0.35 to about 0.85) tan (5) value as a trade-off between dispersion viscosity and stability, as well as a substantially constant tan (5) value over as wide a range of shear stress as possible. Thus, in some embodiments according to the present application, the dispersion can be characterized by a loss factor tan (5) of about 0.35 to about 0.85 at a shear stress range of 0.1 Pa and about 0.001 Pa to about 2 Pa when tested by a Modular Compact Rheometer. Further, the dispersion of the present application can be further characterized by a loss factor tan (5) of about 0.4 to about 0.8, or about 0.45 to about 0.75 at a shear stress range of about 0.001 Pa to about 2 Pa when tested by a Modular Compact Rheometer. In certain embodiments, the described loss factor tan (5) range can be obtained over a shear stress range of from about 0.05 Pa to about 1 Pa when tested by a Modular Compact Rheometer. By controlling the loss factor within the specified range, one skilled in the art can tailor the rheological properties of the dispersion to suit various application requirements.

[0057] Thus, a second aspect of the present application is directed to a cathode slurry composition comprising the dispersion as described above, an active lithium material, a binder, and a dispersion medium. In preferred embodiments of these aspects, the dispersion, the active lithium material, and the binder are homogeneously mixed in the dispersion medium. In particular embodiments, the weight ratio of the active lithium material : the carbonaceous particulate material present in the dispersion : the binder in the cathode slurry composition is: 95 to 97 : 0.3 to 4.0 : 0.5 to 4.0 or 95 to 97 : 0.4 to 3.0 : 0.5 to 4.0 or 95 to 97 : 0.5 to 2.0 : 0.5 to 4.0 or 95 to 97 : 0.3 to 4.0 : 2.0 to 4.0 or 95 to 97 : 0.4 to 3.0 : 2.0 to 4.0 or 95 to 97 : 0.5 to 2.0 : 2.0 to 4.0.

[0058] The active lithium material forms a major portion by weight of the cathode slurry material and provides the lithium ions to the final lithium ion battery. The active lithium material can be included in the slurry composition from about 60 wt% to about 80 wt%, or from about 65 wt% to about 75 wt%, based on the weight of the final cathode slurry composition. In some embodiments, the active lithium material is lithium nickel cobalt manganese oxide.

[0059] The cathode slurry includes a dispersing medium to ensure good processability. In certain embodiments, the dispersing medium is the same as the dispersing medium used in the inventive dispersion. Alternatively, the dispersing medium of the cathode slurry can be selected from organic solvents. Optionally, the organic solvent used as the dispersing medium is an amide-based solvent. Further optionally, the dispersing medium used in the dispersion is N-methyl-2-pyrrolidone (NMP).

[0060] In addition, the cathode slurry includes a binder compound. The binder can be included in the slurry composition from about 1 wt% to about 5 wt%, optionally from about 1.5 wt% to about 4.5 wt%, based on the weight of the final slurry composition. The binder can be an organic polymer, optionally wherein the binder is polyvinylidene fluoride (PVDF).

[0061] Finally, the cathode slurry composition can be characterized by its total solids content in the slurry, wherein the total solids content includes the lithium active material, the conductive additive, and the binder. In some embodiments, the total solids content of the cathode slurry can additionally or alternatively be from about 35 wt% to about 90 wt%. The solids content can also be from about 45 wt% to about 85 wt%, or from about 55 wt% to about 80 wt%, or from about 65 wt% to about 75 wt%.

[0062] As part of the third aspect of the invention, a cathode is described, wherein the cathode is produced by applying the cathode slurry according to the second aspect on a substrate and subsequently drying the coated substrate at a temperature of at least 100 °C for at least 5 minutes.

[0063] The substrate serves as a structural support and conductive substrate for the cathode paste applied thereon. In some embodiments, the substrate is a metal foil, optionally wherein the metal foil comprises at least one metal, or an alloy comprising the at least one metal, or a mixture comprising the at least one metal. The metal foil to be used in the cathode according to the present application typically has any thickness suitable for use in an electrode, typically considered to be 1 μιη to 50 μιη. In certain above-mentioned embodiments, the metal, or an alloy comprising the at least one metal, or a mixture comprising the at least one metal comprises aluminum, iron, zinc, nickel, copper, silver, and / or gold.

[0064] The cathode paste as described above is applied to the substrate by any suitable means. Within some embodiments, the cathode paste is applied to the substrate by a roll-to-roll process. In some embodiments, the coated substrate can be pressed after the drying process to increase the loading density of the coating on the cathode.

[0065] Furthermore, within the fourth aspect of the present application, a lithium ion battery comprising a cathode as described above is described. Such a cathode will be manufactured using a dispersion according to the first aspect of the present application as described above. The lithium ion battery according to the present application shows improved properties such as, for example, improved direct contact resistance, discharge rate, and / or capacity retention after prolonged storage.

[0066] Finally, in the fifth and last aspect of the present application, a method of manufacturing a dispersion according to the first aspect of the present application is described.

[0067] In a first step of the method, the dispersant is dispersed in the dispersion medium. Both the dispersant and the dispersing agent are as described in the first aspect of the present application. Then, in a second step, carbon black particles as described above are added to the mixture of dispersion medium / dispersant. In a third step, carbon nanotube particles as defined in the first aspect of the present application are added to the resulting mixture. Finally, in a fourth step, the mixture comprising dispersion medium / dispersant / CB particles / CNT particles is processed in a mill until the dispersion is obtained. Optionally, the dispersion according to the fifth aspect of the present application can be characterized by the dispersion parameters as described above for the dispersion according to the first aspect of the present application.

[0068] Thus, in a particular embodiment, the second step of the method comprises adding carbon black particles characterized by a BET SSA of about 40 m 2 / g to about 650 m 2g, an oil absorption number (OAN) of about 230 mL / 100 g to about 400 mL / 100 g, a ratio of a compression oil absorption number (cOAN) to the OAN (cOAN / OAN) of about 0.2 to about 0.85, and less than about 235 primary particles per aggregate. The third step of the method includes adding carbon nanotube particles characterized by an outer diameter of about 9 nm to about 18 nm and a D 50 length. The dispersion obtained by this embodiment of the present application is characterized by a total amount of carbonaceous particles (referring to the sum of CB particles and CNT particles) of about 1.5 wt% to about 10 wt% relative to the total weight of the final dispersion, a viscosity of about 1.0 Pa s to about 6.8 Pa s, and / or a yield stress of at least about 1.0 Pa and at most 26.0 Pa, the yield stress being defined as the intersection of G' and G".

[0069] In some embodiments, the method as described above can further include an additional mixing step during any of the steps one to three, or between steps one to four. The parameters of the constituent carbon black and / or carbon nanotube particles must be determined prior to the dispersion formation / treatment step, as it is not possible to reliably measure the physical parameters of the constituent carbon black / carbon nanotube particles after the dispersion formation. The CB and / or CNT particle characteristics and / or their measurement are affected by the presence of the dispersant in the dispersion medium. Therefore, a parameter measurement after the dispersion formation / adding of the CB and / or CNT particles to the dispersion medium containing the dispersant is not feasible.

[0070] The treatment step to produce the final dispersion of CB particles and CNT particles can suitably be performed in any device capable of high energy mixing. In some embodiments, the processing is performed in a bead mill. Therein, any commonly available bead material, such as zirconia oxide beads, can suitably be used for performing the processing step in a bead mill. In some embodiments, the mixing speed of the employed equipment is set to about 10 m / s to about 15 m / s, while the temperature is kept below 40°C during the treatment. In a particular embodiment, the mixing speed is set to 14 m / s, while the temperature is kept below 40°C during the processing.

[0071] In the dispersion formation process, the amount of mixing power applied to the sample per gram of total carbonaceous particulate material (understood as CB and / or CNT material) can additionally or alternatively be described. Without wishing to be bound by theory, applying insufficient mixing power and / or mixing time insufficient to the carbonaceous particulate material sample can not result in the formation of a properly stable dispersion. At the same time, applying too much mixing power and / or mixing the sample under high power for too long can affect the rheological and stability properties of the final dispersion by affecting the particles of the dispersion via excessive shear forces, as understood by the skilled person. In suitable embodiments, a mixing power of about 200 W / g to about 1000 W / g of total carbon black can be applied to the sample. Optionally, the mixing power can be about 250 W / g to about 900 W / g, or about 250 W / g to about 800 W / g of total carbon black. In particular embodiments for dispersing carbonaceous particulate material to obtain the dispersion of the application, a mixing power of about 300 W / g to about 700 W / g of total carbon black is applied to the sample. Additionally or alternatively, in some embodiments, the mixing time is set to about 20 to about 40 minutes, such as for example to about 30 minutes. In preferred embodiments, a mixing power of CB and / or CNT material of between about 300 W / g to about 700 W / g is applied to the sample for about 20 to 40 minutes, while the temperature is kept below 40 °C during the process.

[0072] Finally, the present application also relates to the dispersion obtained by the above-mentioned method. In certain embodiments, the dispersion obtained by the method can be characterized by the dispersion parameters as described above for the dispersion according to the first aspect of the application. Thus, in particular embodiments of the dispersion as obtained by the method, the dispersion is characterized by a total amount of CB particles and CNT particles of about 1.5 wt% to about 10 wt%, a viscosity of about 1.0 Pa s to about 6.8 Pa s, and / or a yield stress of at least about 1.0 Pa and at most 26.0 Pa, the yield stress being defined as the cross-over point of G’ and G”.

[0073] Definitions

[0074] The term "about" as used herein in the context of a parameter or a value, unless otherwise indicated, includes ± 10% of the given value.

[0075] It should be noted that the terms "a" or "an" entity refer to one or more of that entity; for example, "a carbonaceous particulate material" is understood to mean one or more carbonaceous particulate materials. As such, the terms "a" (or "an"), "one or more," and "at least one" can be used interchangeably herein.

[0076] Furthermore, as used herein, "and / or," whereever used, is to be interpreted to mean either "and / or" in the sense of the two stated features being present in either conjunction, or in the sense of one or the other stated features being present. Likewise, "or" should be interpreted to mean either "or" in the sense of the two stated features being present in either conjunction, or in the sense of one or the other stated features being present. As used herein, the phrase "and / or," as used in a phrase such as "A and / or B" means "A and B" or "A or B" or "A" (alone), or "B" (alone). Likewise, as used herein, the phrase "and / or," as used in a phrase such as "A, B, and / or C" means "A, B, and C"; "A, B, or C"; "A or C"; "A or B"; "B or C"; "A and C"; "A and B"; "B and C"; "A" (alone); "B" (alone); and "C" (alone).

[0077] It is to be understood that wherever aspects are described herein with the language "comprising" either "consisting of" and / or "consisting essentially of," then by default, the aspects can also "consist of."

[0078] Unless otherwise stated, percentage (%) values specified herein are by weight.

[0079] Units, prefixes, and symbols are denoted in their Systeme International de Unites (SI) accepted form. Numeric ranges are inclusive of the numbers defining the range.

[0080] The headings provided herein are not limitations of the various aspects of the disclosure, which can be had by reference to the specification as a whole. Accordingly, the terms defined herein direct the scope of the disclosure, which is further defined by reference to the entire specification.

[0081] The term "C-rate" as used herein is used to describe the speed at which a battery is fully charged or discharged. For example, a C-rate of 1 C fully discharges a charged battery in 1 hour.

[0082] The terms "storage modulus" or "G'" are used interchangeably herein and describe the ability of a material to elastically store energy.

[0083] The terms "loss modulus" or "G"" are used interchangeably herein and describe a measure of energy dissipated as heat when a stress is applied to a viscous material.

[0084] The term "yield stress" as used herein describes the apparent yield stress characterizing dispersions beyond a critical volume fraction of network spanning the sample. Such dispersions show a high-elastic, gel-like behavior against shear forces below their yield stress. Applying forces above the yield stress of the dispersion leads to shear-induced breakdown and thixotropic behavior.

[0085] Method for measuring properties of lithium ion batteries of carbon black, carbon nanotubes or dispersions and their preparation

[0086] Suitable methods for determining the various properties and parameters of the dispersions according to the application and their constituents carbon black and / or carbon nanotubes as well as their ingredients are described in detail below.

[0087] BET solid specific surface area [m 2 / g]

[0088] The method is based on recording the adsorption isotherm of liquid nitrogen at 77 K in the pressure range p / p0 = 0.01 - 0.995, wherein p0 is the saturation pressure. Nitrogen adsorption was performed on an ASAP 2020 from Micromeritics. Prior to analysis, the samples were degassed in vacuum at 573 K for at least 8 hours. According to the procedure proposed by Brunauer, Emmett and Teller (Adsorption of Gases in Multi-molecular Layers, J. Am. Chem. Soc., 1938, 60, 309 - 319), the monolayer capacity can be determined. Based on the cross-sectional area of a nitrogen molecule, the monolayer capacity, and the weight of the sample, the specific surface area can then be calculated. The isotherm was measured at 77 K in the pressure range p / p0 0.05 - 0.2. J. Am. Chem. Soc.

[0089] Reference: S. Brunauer, P. H. Emmett, E. Teller, J. Am. Chem. Soc., 1938, 60, 309 - 319. J. Am. Chem. Soc.

[0090] Average number of primary particles per aggregate and degree of branching by transmission electron microscopy (TEM) The aggregation parameter was obtained according to ASTM D 3849 by evaluating a representative set of TEM images of about 1000 well dispersed and isolated aggregates by image analysis software. Prior to TEM evaluation, the powders were dispersed in a 2:1 water / isopropanol mixture by ultra-sonication.

[0091] Reference: ASTM D 3849

[0092]

[0093] Particle size distribution (PSD) by laser diffraction

[0094] ​​An amount of 0.02 g of CNT powder was dispersed in 5 ml of 1 wt% PVP K30 ethanol dispersion by ultrasonication. Typically, a LASER beam illuminates a small chamber containing a sample of CNTs suspended in water, the diffraction pattern generated is collected by the system and analyzed using the light scattering theory developed by Mie. The particle size distribution by volume is calculated and three fractiles are reported in pm: 10% (D 10 ), 50% (D 50 ) and 90% (D 90 ). Here, a Horiba Laser Scattering PSD analyzer LA-950 was used.

[0095] Reference: GB / T 19077.1 - 2008 / ISO 13320 - 1 :1999

[0096] Oil absorption number (OAN) [mL / 100 g]

[0097] OAN is measured according to ASTM D2414 (Procedure A). Paraffin oil is added to a dry carbon black sample in the mixing chamber of an absorptometer. As the sample absorbs oil, the viscosity increases. When the viscosity reaches a predetermined torque level (400 mNm), the volume of oil added is read. The volume of oil per unit mass of carbon black is the OAN.

[0098] Reference: ASTM D2414 - 01

[0099] To measure the compressed oil absorption value (cOAN), the carbon black sample is compressed four times at a pressure of 165 MPa and then tested in an absorptometer to determine the oil absorption value according to method ASTM D2414-01 (see above). The difference between the initial OAN number and the OAN number of the compressed sample reflects the stability of the structure of this sample.

[0100] Reference: ASTM D3493 - 14

[0101] Method for the measurement of the rheological properties of dispersions

[0102] The measurements were performed using an MCR 302 modular rheometer from Anton Paar. The plate was a CP50-2 cone-plate (50 mm diameter plate with a 2° cone angle). The device was regularly calibrated with a standard oil called S600. The rheometer was initialized and the zero gap position was determined by the test software before the test.

[0103] Viscosity measurements

[0104] The sample stage was pre-conditioned at 25 °C. About 3 grams of dispersion was loaded onto the sample stage. The cone plate was set to the measurement position and the overflow dispersion was wiped away. The dispersion was measured from a low shear rate of 0.01 Hz to a high shear stress of 1000 Hz and then back to a low shear stress of 0.01 Hz. The shear rate was changed in an exponential pattern. A total of 42 sample points were taken in one run. The viscosity values were read at 1 Hz in the reverse scan.

[0105] Reference: Chiou K. et al., PNAS, 2018, 115 (22), 5703 - 5708.

[0106] Dynamic mechanical analysis (DMA) of dispersions / storage modulus G' / loss modulus G"

[0107] The DMA analysis was performed by fixing the frequency at 1 Hz. An amplitude sweep (y = 0.1% to 1000%) was performed to determine the stability range of the different pastes.

[0108] Method for benchmarking lithium ion batteries comprising carbon black dispersions according to the invention

[0109] Direct contact resistance (DCR) [mΩ]

[0110] The DCR test was performed at room temperature (R.T. = 25 °C) and low temperature (L.T. = -10 °C): First, the battery cell was charged to 50% state of charge (SOC) at 25 °C. The cell was then maintained at the preset temperature (R.T. or L.T.) for 3 hours. The DCR was measured by applying a series of discharge pulse currents at C-rates of 0.2 C, 0.5 C and 1 C. The C-rate describes the speed at which a battery is fully discharged (or charged). For example, charging at a C-rate of 1 C means that the battery is fully discharged in 1 hour. Each current lasted for 5 seconds. The DCR was calculated by the following equation:

[0111] Discharge energy of L.T. at 1 C test: The battery was fully charged at R.T. and then placed in a temperature chamber at -10 °C for 3 hours. It was then discharged at -10 °C (L.T.) at a C-rate of 1 C to 2.5 V. The discharge energy was calculated by the following equation:

[0112] Discharge at 5 C

[0113] The discharge rate performance test was performed by the following steps: discharging the battery at constant current-constant voltage (C C - C VThe mode will charge the battery to 4.2 V. The battery is discharged at n C (n = 0.2, 0.5, 1.0, 2.0, 3.0, 5.0, respectively) constant current to 2.5 V. The discharge rate is calculated based on the following equation:

[0114] High temperature (H.T.) capacity retention test: The battery is fully charged to 100% state of charge (SOC) and stored at a constant temperature of 60 °C for the specified period. The battery is then cooled to 25 °C.

[0115] The remaining capacity is checked by discharging the battery to 2.5 V at 1.0 C. Capacity retention after 4 weeks = discharged capacity after storage / discharged capacity at 1.0 C

[0116] H.T. storage impedance growth test: The electrochemical impedance test is performed after recharging the battery to SOC 100%. Impedance growth is obtained from the test.

[0117] Various aspects of the application have been generally described that persons skilled in the art will realize that modifications and slight variations are possible without departing from the spirit and scope of the application. The application is further described by reference to the following numbered, non-limiting examples: 1. A dispersion comprising: a) carbon black (CB) particles, wherein the carbon black particles are characterized by (i) a BET SSA of about 40 m 2 / g to about 650 m 2 / g; (ii) an oil absorption number (OAN) of about 230 mL / 100 g to about 400 mL / 100 g; (iii) a ratio of compressed oil absorption number (cOAN) to OAN (cOAN / OAN) of about 0.2 to about 0.85; and (iv) less than about 235 primary particles per aggregate, b) carbon nanotube (CNT) particles, wherein the carbon nanotube particles are characterized by (v) an outer diameter of about 9 nm to about 18 nm; and (vi) a D 50 length of about 1 μm to about 13 μm, and c) a dispersion medium, wherein the dispersion includes a carbon black ratio of CNT particles to CB particles of about 10 : 1 to about 1 : 1 by weight.

[0118] 2. The dispersion of embodiment 1, wherein the CB particles are characterized by a BET SSA of about 50 m 2 / g to about 630 m 2 / g, optionally wherein the CB particles are characterized by a BET SSA of about 60 m 2 / g to about 610 m 2 / g.

[0119] 3. The dispersion of embodiment 1 or embodiment 2, wherein the CB particles are characterized by an oil absorption number (OAN) of about 240 mL / 100 g to about 380 mL / 100 g, optionally wherein the carbon black is characterized by an OAN of about 250 mL / 100 g to about 360 mL / 100 g, or about 260 mL / 100 g to about 340 mL / 100 g.

[0120] 4. The dispersion of any one of embodiments 1 to 3, wherein the CB particles are further characterized by a compressed oil absorption number (cOAN) of about 80 mL / 100 g to about 270 mL / 100 g, optionally wherein the CB particles are further characterized by a cOAN of about 90 mL / 100 g to about 260 mL / 100 g, or about 100 mL / 100 g to about 250 mL / 100 g, or about 110 mL / 100 g to about 240 mL / 100 g.

[0121] 5. The dispersion of any one of embodiments 1 to 4, wherein the CB particles are characterized by a ratio of cOAN to OAN of about 0.25 to about 0.825, optionally wherein the CB particles are characterized by a ratio of cOAN to OAN of about 0.3 to about 0.8, or about 0.35 to about 0.775, further optionally wherein the ratio of cOAN to OAN is less than about 0.77.

[0122] 6. The dispersion of any one of embodiments 1 to 5, wherein the CB particles are characterized by less than about 220 primary particles per aggregate, optionally wherein the CB particles are characterized by less than about 200 or less than about 180 primary particles per aggregate.

[0123] 7. The dispersion of any one of embodiments 1 to 6, wherein the CB particles are further characterized by a degree of branching of about 7 to about 18, Optionally wherein the CB particles are further characterized by a branching degree of about 8 to about 17, or 9 to 16, Further optionally wherein the branching degree is less than 16.

[0124] 8. The dispersion of any one of embodiments 1 to 7, wherein the CB particles are further characterized by a Scott density of about 0.01 g / cm 3 to about 0.1 g / cm 3 , Optionally wherein the CB particles are further characterized by a Scott density of about 0.02 g / cm 3 to about 0.09 g / cm 3 , or about 0.03 g / cm 3 to about 0.08 g / cm 3 , or about 0.04 g / cm 3 to about 0.7 g / cm 3 , or about 0.045 g / cm 3 to about 0.065 g / cm 3 .

[0125] 9. The dispersion of any one of embodiments 1 to 8, wherein the CB particles are selected from thermal carbon black, acetylene black, or furnace black.

[0126] 10. The dispersion of any one of embodiments 1 to 9, wherein the CNT particles are characterized by an outer diameter of about 10 nm to about 16 nm.

[0127] 11. The dispersion of any one of embodiments 1 to 10, wherein the CNT particles are further characterized by a BET SSA of about 230 m 2 / g to about 400 m 2 / g, Optionally wherein the CNT particles are further characterized by a BET SSA of about 240 m 2 / g to about 350 m 2 / g or about 250 m 2 / g to about 310 m 2 / g. Further optionally wherein the CNT particles are further characterized by a BET SSA of less than 300 m 2 / g.

[0128] 12. The dispersion of any one of embodiments 1 to 11, wherein the CNT particles are characterized by a D 50 length of about 2 μm to about 11 μm, Optionally wherein the CNT particles are characterized by a D 50 length.

[0129] 13. The dispersion according to any one of embodiments 1 to 12, wherein at least a portion of the CNT particles are multi-walled.

[0130] 14. The dispersion according to any one of embodiments 1 to 13, wherein the dispersion medium is an organic solvent, Optionally wherein the organic solvent is an amide-based solvent, Further optionally wherein the amide-based solvent is N-methyl-2-pyrrolidone (NMP).

[0131] 15. The dispersion according to any one of embodiments 1 to 14, wherein the dispersion medium further comprises a dispersant, Optionally wherein the dispersant is an organic dispersant, Further optionally wherein the organic dispersant is a polymeric organic dispersant, Further optionally wherein the polymeric organic dispersant is polyvinylpyrrolidone (PVP).

[0132] 16. The dispersion according to any one of embodiments 1 to 15, wherein the dispersion medium comprises the dispersant in an amount less than about 2 wt%, Optionally wherein the dispersant is comprised in the dispersion medium in an amount less than about 1.8 wt%, or less than about 1.6 wt%, or less than about 1.4 wt%, or less than about 1.2 wt%, or less than about 1.0 wt%.

[0133] 17. The dispersion according to any one of embodiments 1 to 16, characterized in that the dispersion has

[0134] d) a total amount of CB particles and CNT particles of about 1.5 wt% to about 10 wt%; e) a viscosity of about 1.0 Pa s to about 6.8 Pa s when tested by a modular compact rheometer at a shear rate of 1 Hz; and / or f) a yield stress of at least about 1.0 Pa and at most 26.0 Pa, the yield stress being defined as the intersection point of G' and G".

[0135] 18. The dispersion according to any one of embodiments 1 to 17, wherein the total amount of CB particles and CNT particles in the dispersion is about 2 wt% to about 9 wt%, Optionally wherein the total amount of CB particles and CNT particles in the dispersion is about 2.5 wt% to about 8 wt%, or about 3 wt% to about 7 wt%, or about 3.5 wt% to about 6 wt%.

[0136] 19. The dispersion according to any one of embodiments 1 to 18, wherein the dispersion is characterized by a viscosity of about 1.2 Pa s to about 6.6 Pa s at a shear rate of 1 Hz when tested by a Modular Compact Rheometer, Optionally wherein the dispersion is characterized by a viscosity of about 1.4 Pa s to about 6.4 Pa s at a shear rate of 1 Hz when tested by a Modular Compact Rheometer.

[0137] 20. The dispersion according to any one of embodiments 1 to 19, wherein the dispersion is characterized by a yield stress of at least about 1.2 Pa and at most about 24.0 Pa, the yield stress being defined as the intersection of G’ and G”, Optionally wherein the dispersion is characterized by a yield stress of at least about 1.5 Pa and at most about 22.0 Pa, the yield stress being defined as the intersection of G’ and G”.

[0138] 21. The dispersion according to any one of embodiments 1 to 20, wherein the dispersion is characterized by a loss modulus (G”) of about 0.5 Pa to about 50 Pa and a storage modulus (G’) of about 0.5 Pa to about 150 Pa at a shear stress range of about 0.001 Pa to about 2 Pa when tested by a Modular Compact Rheometer, Optionally wherein the dispersion is characterized by a loss modulus (G”) of about 1 Pa to about 45 Pa and a storage modulus (G’) of about 1 Pa to about 140 Pa, or a loss modulus (G”) of about 2 Pa to about 40 Pa and a storage modulus (G’) of about 2 Pa to about 130 Pa at a shear stress range of about 0.001 Pa to about 2 Pa when tested by a Modular Compact Rheometer.

[0139] 22. The dispersion according to any one of embodiments 1 to 21, wherein the dispersion is characterized by a loss factor tan(5) of about 0.35 to about 0.85 at a shear stress of 0.1 Pa at a shear stress range of about 0.001 Pa to about 2 Pa when tested by a Modular Compact Rheometer, Optionally wherein the dispersion is characterized by a loss factor tan (5) of about 0.4 to about 0.8, or about 0.45 to about 0.75, when tested by a Modular Compact Rheometer at a shear stress ranging from about 0.001 Pa to about 2 Pa.

[0140] 23. A cathode slurry composition comprising: g) the dispersion of any one of embodiments 1 to 22; h) an active lithium material; i) a dispersing medium; and j) a binder.

[0141] 24. The cathode slurry composition according to embodiment 23, wherein

[0142] k) the dispersion of any one of embodiments 1 to 22 is comprised in the slurry composition at about 0.3 wt% to about 3 wt%, optionally about 0.4 wt% to about 2.5 wt%, or about 0.5 wt% to about 2 wt%; l) the active lithium material is comprised in the slurry composition at about 60 wt% to about 80 wt%, optionally about 65 wt% to about 75 wt%; further optionally wherein the active lithium material is lithium nickel cobalt manganese oxide; m) the dispersing medium is N-methyl-2-pyrrolidone (NMP); n) the binder is comprised in the slurry composition at about 1 wt% to about 5 wt%, optionally about 1.5 wt% to about 4.5 wt%; further optionally wherein the binder is an organic polymer, further optionally wherein the binder is polyvinylidene fluoride (PVDF); and / or o) wherein the final solids content of the slurry composition is about 35 wt% to about 90 wt%, optionally wherein the solids content is about 45 wt% to about 85 wt%, or about 55 wt% to about 80 wt%, or about 65 wt% to about 75 wt%.

[0143] 25. A cathode, wherein the cathode is produced by applying the cathode slurry composition according to embodiment 23 or embodiment 24 on a substrate and subsequently drying the coated substrate at a temperature of at least 100 °C for at least 5 minutes.

[0144] 26. The cathode according to embodiment 25, wherein the substrate is a metal foil, optionally wherein the metal foil comprises at least one metal, or an alloy comprising the at least one metal, or a mixture comprising the at least one metal, Further optionally wherein the metal, or alloy comprising the at least one metal, or mixture comprising the at least one metal comprises aluminum, iron, zinc, nickel, copper, silver, and / or gold.

[0145] 27. The cathode according to either embodiment 25 or embodiment 26, wherein the composition is applied to the substrate by a roll-to-roll process.

[0146] 28. A lithium ion battery comprising the cathode according to embodiment 27.

[0147] 29. A method of making a dispersion, the method comprising: p) dispersing a dispersant in a solvent; q) adding carbon black (CB) particles to the solvent, wherein the carbon black is characterized by (vii) a BET SSA of about 40 m 2 / g to about 650 m 2 / g; (viii) an oil absorption number (OAN) of about 230 mL / 100 g to about 400 mL / 100 g; (ix) a ratio of a compressed oil absorption number (cOAN) to the OAN (cOAN / OAN) of about 0.2 to about 0.85; and (x) less than about 235 primary particles per aggregate; r) adding carbon nanotube (CNT) particles to the solvent, wherein the carbon nanotubes are characterized by (xi) an outer diameter of about 9 nm to about 18 nm; and (xii) a D 50 length of about 1 pm to about 13 pm; s) mixing the solvent comprising the dispersant, the CB particles, and the CNT particles in a mixer, wherein the CNT particles and the CB particles are added to each other in a ratio of about 10 : 1 (w / w) to about 1 : 1 (w / w).

[0148] 30. The method according to embodiment 29, wherein the mixing step comprises applying a mixing power of about 200 W / g to about 1000 W / g of total carbon black within the sample.

[0149] Optionally, the mixing power applied is between about 250 W / g to about 900 W / g, or between about 250 W / g to about 800 W / g, or between about 300 W / g to about 700 W / g of total carbon black within the sample.

[0150] Further optionally, wherein the mixing time of the mixing step is set to about 20 to about 40 minutes, such as 30 minutes

[0151] 31. The method according to either embodiment 29 or embodiment 30, wherein the final dispersion is characterized by

[0152] t) a total amount of CB particles and CNT particles between about 1.5 wt% and about 10 wt%; u) a viscosity of about 1.0 Pa s to about 6.8 Pa s, and / or v) a yield stress of at least about 1.0 Pa and at most 26.0 Pa, the yield stress being defined as the intersection of G’ and G”.

[0153] Examples

[0154] Example 1 - Physical properties of carbon black

[0155] The physical properties of various carbon black particles according to the present application were measured and compared to the physical properties of various known / commercially available comparative carbon black particles.

[0156] CB 1 particles are a commercially available product under the trade designation C-NERGY TM Super C65 conductive carbon black. CB 2 particles are a commercially available product under the trade designation C-NERGY TM Super C130 conductive carbon black. CB 3 particles are a commercially available product under the trade designation C-NERGY TM Super C600 conductive carbon black.

[0157] For comparative dispersion examples, common commercially available carbon black particles (cCB 1 - cCB 3 particles) were used.

[0158] The physical properties of carbon black materials (carbon black CB 1 - CB 3) to be used in dispersions according to the present disclosure were compared to known and commercially available comparative carbon black materials cCB 1 - cCB 3.

[0159] Table 1: Physical properties of carbon black

[0160] As evident from the above table, the carbon black particles tested for dispersion cover a wide range of BET SSA (50 m 2 / g - 750 m 2 / g). Typically, an attempt was made to benchmark the CB particles according to the application with comparative cCB particles having a similar BET SSA. Overall, the cCB particles were characterized by a higher cOAN / OAN ratio and a higher Scott density compared to the CB particles according to the application.

[0161] Example 2 - Carbon black dispersions

[0162] Different types of carbon black show different behavior in dispersions. Some disperse easily, some do not. In addition, after dispersion by a dispersion process, some CB do not show sufficient dispersion stability, meaning that the particles will aggregate and separate from the liquid phase. This indicates a weak interaction between the CB particles and the dispersant. Part of the objective of the present application is to determine CB and / or CNT parameters that enable reliable formation of suitable and stable CB + CNT dispersions.

[0163] To investigate the interaction between CB in highly concentrated dispersions, the rheological properties, i.e. viscosity and yield stress, of various carbon black dispersions comprising CB particles according to the application and comparative cCB particles as listed under Example 1 were further analyzed. The yield stress thus marks the point at which an externally applied stress causes a breakdown of the indirect (solvent-particle) "lubricated" contact between the particles. Carbon black dispersions were prepared from CB particles according to the application and comparative cCB particles of Table 1.

[0164] For dispersion formation of CB (and CNT) particles, high mixing forces have to be applied. The parameters of the carbon black have to be measured before dispersion formation, because the physical parameters of the carbon black cannot be measured after dispersion formation due to the presence of the dispersant. The same dispersion method was used for all carbon blacks to allow for mutual comparability between the individual dispersions.

[0165] For dispersion formation of the comparative CB dispersions, the dispersant polyvinylpyrrolidone (PVP) was first pre-dispersed in N-methylpyrrolidone (NMP) as solvent. The CB particles were gradually added under mechanical mixing. The concentration of PVP was 1% wt and the total concentration of carbon black was between 8.5% wt% and 10% wt%. This initial mixture was transferred to a bead mill manufactured by Ashizawa (Labstar mini LMZ015) and zirconia beads with a diameter of 0.5 mm were used. The total filling rate of the milling chamber was 85%. The mixing speed of the machine was set to 15 m / s while the milling / dispersion time was 3 minutes at below 40°C. After this process, the carbon black dispersions to be tested were obtained. The rheological properties of the CB dispersions thus obtained are summarized in Table 2 below.

[0166] Table 2: Composition and rheological properties of carbon black dispersions

[0167] Dynamic mechanical analysis (DMA) of the dispersions listed above is shown in Figure 1A , Figure 1B , Figure 2A and Figure 2B . Generally speaking, in order to have sufficient dispersion stability during storage, the dispersion should have a higher storage modulus G’ relative to the loss modulus G” (Hawley, W. Blake and J. Li, Macromolecules 2019, 26, 100994). Journal of Energy Storage, 2019, 26, 100994).

[0168] For the dispersions, the tan(5) values reported herein (see Tables 2, 4, 6) were averaged from the first measurable data point tan(5) (first value) to the data point tan(5) (first value + 0.05 Pa) to account for the shift within the first few reported tan(5) values. The complete tan(5) plot is reported as Figure 2A , Figure 2B , Figure 7A , Figure 7B , Figure 8 , Figure 9A and Figure 9B .

[0169] For cCB1, the observed “plateau region” of G’ over G” is very narrow ( Figure 1B ). At the same time, for cCB2, the dispersion shows G” > G’ on the DMA analysis, indicating an unstable dispersion behavior. This shows that cCB1 and cCB2 do not form sufficiently stable dispersions at high carbon black concentrations. On the other hand, cCB3 shows a significantly high modulus and high yield stress, which is one order of magnitude higher than the others. However, it also demonstrates a variety of “solid-like” behavior, as evidenced by its very high viscosity, which makes the handling of the dispersion very challenging. However, the inventors have for the first time recognized that for a given BET, the selection of carbon black particle starting materials with a lower carbon black cOAN / OAN ratio will enable the skilled person to obtain a more favorable and easy-to-handle dispersion, which is characterized by parameters such as processable viscosity (about 0.1 Pa s to 8.0 Pa s) (see Figures 1A to 2B ).

[0170] Example 3 - Carbon nanotube dispersions

[0171] To illustrate how carbon nanotube dispersions are affected by the presence of different carbon blacks in the dispersion, three different types of carbon nanotubes were chosen to be tested in combination with various carbon blacks. CNT 1 particles are commercially available under the trade name Cabot Enermax 31 or Cnano FT9100. CNT 2 particles are commercially available under the trade name Nanocyl NX7100 or Cnano FT7230. CNT 3 particles are commercially available under the trade name JEIO Tube8B or Cnano FT6100 or Cnano FT6120. The above listed CNT trade names are not exhaustive and CNTs are also available under other trade names. The parameters of the carbon nanotubes are summarized in Table 3: Table 3: Physical properties of carbon nanotubes

[0172] Comparative dispersions were prepared from CNT 1 particles to CNT 3 particles to demonstrate the effect of various CNT parameters on the resulting CNT dispersions. During the dispersion formation process of the carbon nanotube (CNT) (and / or carbon black + carbon nanotube (CB + CNT)) particles, a high milling force is applied. The parameters of the constituent carbon nanotube (and / or carbon black) particles must be measured before dispersion formation, as the physical parameters of the carbon black / carbon nanotube particles cannot be measured after dispersion formation due to the presence of the dispersant. The same dispersion method for dispersion was used to allow for intercomparisons between the individual dispersions.

[0173] For the dispersion formation of the comparative CNT particle dispersions, the dispersant polyvinylpyrrolidone (PVP) was first pre-dispersed in N-methylpyrrolidone (NMP) as solvent. The CNT particles were gradually added under mechanical mixing. The concentration of PVP was 1 wt% and the concentration of CNT is shown in Table 4. This initial mixture was transferred to a bead mill manufactured by Ashizawa (Labstar mini LMZ015) and zirconia beads with a diameter of 0.5 mm were used. The total filling rate of the milling chamber was 85%. After proper wetting of the carbon powder, the mixing speed of the machine was set to 14 m / s while the milling / dispersion time was 30 min at below 40 °C to obtain the CNT particle dispersions. After this process, the carbon black / carbon nanotube dispersions to be tested were obtained. The obtained CNT particle dispersions are summarized in Table 4: Table 4: Composition and rheological properties of carbon nanotube dispersions

[0174] Table 4 shows that for dispersions containing only carbon nanotubes without the addition of carbon black, the parameter that most influences the dispersion properties is the amount of dispersed CNT particles. Furthermore, when comparing the above examples (especially cCNT 1 and cCNT 4), it becomes apparent that the average length D of the starting carbon nanotubes 50 it seems to disproportionately influence the dispersion characteristics, with shorter CNTs leading to much higher possible CNT loadings before the dispersion becomes unmanageable.

[0175] Example 4 - Carbon black + carbon nanotube dispersions

[0176] The present inventors surprisingly found that by careful selection of the constituent carbon black and carbon nanotubes and their respective mutual ratios, prior to dispersion preparation, stable dispersions with suitable viscosities and yield stresses can be obtained. Furthermore, it was found that the resulting inventive dispersions are particularly suitable for use in the preparation of lithium-ion battery cathodes.

[0177] For dispersion formation, the dispersant polyvinylpyrrolidone (PVP) was first pre-dispersed in N-methylpyrrolidone (NMP) as solvent. CNT particles were gradually added under mechanical mixing, followed by gradual addition of CB particles under mechanical mixing. The concentration of PVP was 1 wt% and the concentrations of CB and CNT are shown in Table 4. This initial mixture was transferred to a bead mill manufactured by Ashizawa (Labstar mini LMZ015) and zirconia beads with a diameter of 0.5 mm were used. The total filling rate of the milling chamber was 85%. After proper wetting of the carbon powders, the mixing speed of the machine was set to 14 m / s, while the milling / dispersion time was 30 min at below 40 °C to obtain CB particles + CNT particles dispersions. The CB + CNT mixtures tested and the amounts of their respective carbonaceous particulate material constituents are summarized in Table 5 below: Table 5: Composition of carbon nanotube or carbon black + carbon nanotube dispersions

[0178] As can be seen from Table 5, total carbon loadings of about 1.2 wt% to about 5.8 wt% were tested. Generally, the examples with lower total carbon loadings also contained lower dispersant loadings. Different CNT : CB ratios were tested.

[0179] CE 7 was prepared as described above, but due to mixing difficulties, the solid content was much lower. Figure 10 An image of the resulting mixture is shown, which was a very thick paste and not suitable for further testing of its rheological properties.

[0180] Rheological properties of carbon black + carbon nanotube dispersions

[0181] The dispersions 1 to 8 (IE 1 to IE 8) according to the application and the comparative dispersions CE 1 to CE 6 were tested for their rheological properties by DMA analysis. Their respective viscosity, yield stress and tan(5) are summarized in Table 6: Table 6: Rheological properties of carbon black + carbon nanotube dispersions

[0182] The DMA measurements of these dispersions are shown in Figures 3A-1 to 6B , depicting the course of the viscosity, the storage modulus G’ and the loss modulus G” over the shear stress range. In general, in order to have sufficient dispersion stability during storage, the dispersion should have a higher storage modulus G’ relative to the loss modulus G” (Hawley, W. Blake and J. Li, Journal of Energy Storage , 2019, 26, 100994). Furthermore, Figures 7A to 9B the course of the tan(5) values calculated as G” / G’ over the shear stress range of the dispersions is shown.

[0183] From Table 6 in combination with the Figures 3A-1 to 9B depicting the rheological data, it can be observed that the dispersions IE 1 to IE 3 as well as the comparative dispersions CE 1 and CE 2 all show reasonable viscosities (< 3 Pa s) at 1 Hz shear rate. However, the comparative CE 3 shows a much higher viscosity than the rest of the dispersions, even higher than the 5 wt% carbon nanotube dispersion (cCNT 2, 5.68 Pa s). This indicates that CE 3 is not a good candidate for a dispersion that is easy to handle.

[0184] Regarding the stability of the dispersions, the dispersions IE 2 and IE 3 of the application show reasonable G’ > G” over a wide shear stress range, indicating the stability of the dispersions. During the DMA analysis, the comparative dispersions CE l and CE 2 both show an unstable behavior. For both cases, G’ is very close to G”, with several cross-overs when increasing the shear stress. This indicates that agglomerates are formed from time to time with increasing force applied. This will eventually lead to the settling of carbon solids in the dispersion. On the other hand, for the comparative dispersion CE 3, the very clear difference between G’ and G” indicates a solid-like behavior of this dispersion. In fact, in this state, the dispersion already behaves like a vacuum grease, which poses a major challenge for processing.

[0185] In summary, from dispersions IE 1 to IE 4 and contrasts CE 1 to CE 3, each formulated with the same carbon nanotube sample 1, it can be observed that the rheological trends in dispersions comprising a mixture of carbon black and carbon nanotubes follow the trends first observed in example 2, i.e. a lower cOAN / OAN ratio of the starting carbon black particles will lead to more favorable dispersions as characterized by the workable viscosity. In particular, the comparison between the inventive examples IE 1, IE 4 and IE 5 (all prepared with CB 1 and CNT 1) indicates the importance of the ratio between CB and CNT and the effect of an increasing amount of CB on the rheological properties of the final dispersion.

[0186] The comparison of the inventive examples IE 1 to IE 3 (with a total carbon loading of 5.8 wt%) and IE 6 to IE 8 (with a total carbon loading of 3.5 wt%) or the comparison of the contrast dispersions CE 1 to CE 3 with the contrast dispersions CE 4 to CE 6 indicates that the CNT 1 particles seem to allow a higher total carbon loading than the CNT 2 particles while showing favorable dispersion properties. At the same time, it was not possible to form a suitable dispersion with the CNT 3 particles. Finally, the dispersions prepared with the carbon black particles according to the present invention show superior rheological properties compared to the dispersions prepared from the contrast carbon black particles.

[0187] Example 5 - Preparation of a battery using carbon nanotube + carbon black dispersions

[0188] For the anode: The synthetic graphite was weighed and put into the container of the mixer. The powder was then mixed for 5 minutes at low mixing speed. The mixing process can be performed by different mixers used for the production of electrode slurries for coating. For example, a Primix model 2P-03 mixer can be used at a mixing speed of 20 rpm.

[0189] 1 wt% sodium carboxymethyl cellulose (CMC) and 0.5 wt% carbon black dispersion (Imerys Cnergy C65T) were added and mixed for 30 minutes at 50 rpm. The slurry was then mixed for 30 minutes at 80 rpm. Finally, a Styrene-Butadiene Rubber (SBR) (48.5 wt%) suspension was added to the container. The slurry was stirred for 30 minutes at 80 rpm and then degassed for 10 minutes at 20 rpm. DI water was added to adjust the solids content to 49 wt%. The weight ratio between the different components was: graphite : carbon black dispersion : CMC : binder = 97.5 : 0.5 : 1.0 : 1.5.

[0190] The resulting slurry was coated onto a copper foil using a roll-to-roll coater while drying at 80 °C. The loading of the material was 8 mg / cm 2 . The electrode material was pressed to a density of 1.6 g / cm 3 .

[0191] For the positive electrode

[0192] The preparation of the positive electrode used the same mixer as for the negative electrode. The final slurry composition for the positive electrode was: lithium nickel cobalt manganese oxide : carbon black dispersion according to the invention : binder = 96 : 1 : 3, with a solid content of 70%. The solvent used in the positive electrode preparation was N-methyl-2-pyrrolidone (NMP). The conductive additive for one was the conductive additive from dispersion IE 1 according to the invention, and for the comparative cathode was the conductive additive from CE 1.

[0193] The slurry was then coated onto an aluminum foil with a roll-to-roll coater. The drying temperature was 110 °C for about 1 to 2 minutes. The loading of the material was 14 mg / cm 2 . The electrode material was pressed to a density of 3.2 g / cm 3 .

[0194] Preparation of pouch cells

[0195] A 500 mAh pouch cell was assembled in a dry room with a dew point below -40 °C. The electrolyte was 1 M LiPF6 EC / EMC / DMC (1 / 3 volume each) with 1 wt% vinylene carbonate (VC).

[0196] Example 6 - Performance of batteries containing carbon nanotube + carbon black dispersion

[0197] As shown in Examples 1 to 5, the effect of the carbon black component on the handleability and stability of the carbon black + carbon nanotube dispersion has been investigated. The rheological behavior of the carbon black + carbon nanotube dispersion will in turn affect the quality of the electrode slurry prepared therefrom. Higher quality electrodes subsequently show higher battery performance.

[0198] Two pouch cells were prepared, one with a cathode containing the IE 1 dispersion according to the invention, and the other with a cathode containing the CE 1 dispersion with a similar carbon black BET SSA. The parameters of both pouch cells were evaluated, including DCR, discharge rate, and impedance growth after four weeks of high temperature (H.T.) storage, and the results are summarized in Table 7.

[0199] Table 7: Battery performance of different carbon nanotube + carbon black dispersions

[0200] Thus, the optimized carbon black + carbon nanotube dispersion according to the present application is able to form an improved electrode, which in turn leads to improved battery performance.

[0201] In summary, the present inventors have surprisingly found a stable dispersion with suitable rheological properties comprising both CB particles and CNT particles obtainable by careful selection of said CB particles and CNT particles, which has a surprisingly and profound beneficial effect on lithium ion batteries built with cathodes comprising the dispersion of the present application, despite the dispersion of the present application comprising only about 1 wt% as conductive additive in said cathodes. Without wishing to be bound by theory, it is believed that part of the reason the dispersion is able to form an improved cathode is that the dispersion of the present application is able to improve the carbon black conductor distribution within the cathode composition due to improved dispersion properties.

Claims

1. A dispersion comprising: w) Carbon black (CB) particles, wherein, The carbon black particles are characterized in that (i) Approximately 40 m 2 / g to approximately 650 m 2 / g of BET SSA; (ii) Oil absorption value (OAN) of approximately 230 mL / 100 g to approximately 400 mL / 100 g. (iii) The ratio of compression absorbance value (cOAN) to OAN (cOAN / OAN) of approximately 0.2 to approximately 0.85; and (iv) Each aggregate contains fewer than approximately 235 primary particles. x) Carbon nanotube (CNT) particles, wherein the carbon nanotube particles are characterized by: (i) an outer diameter of about 9 nm to about 18 nm; and (ii) D from about 1 μm to about 13 μm 50 Length, and y) Dispersion medium, The dispersion comprises a carbon black ratio of CNT particles to CB particles of about 10:1 to about 1:1 by weight.

2. The dispersion according to claim 1, wherein, The CB particles are further characterized by a branching degree of approximately 7 to approximately 18. Optionally, the CB particles are further characterized by a branching degree of about 8 to about 17, or 9 to 16. Optionally, the degree of branching is less than 16.

3. The dispersion according to any one of claims 1 to 2, wherein, The CNT particles are further characterized by being approximately 230 μm in size. 2 / g to approximately 400 m 2 / g of BET SSA, Optionally, the CNT particles are further characterized by being approximately 240 μm in size. 2 / g to approximately 350 m 2 / g, or approximately 250 m 2 / g to approximately 310 m 2 / g of BET SSA; Further optionally, the CNT particles are further characterized by being less than 300 μm. 2 / g of BET SSA.

4. The dispersion according to any one of claims 1 to 3, wherein, At least a portion of the CNT particles are multi-walled.

5. The dispersion according to any one of claims 1 to 4, wherein, The dispersion medium contains less than about 2 wt% of a dispersant. Optionally, the dispersant is contained in the dispersion medium in an amount of less than about 1.8 wt%, or less than about 1.6 wt%, or less than about 1.4 wt%, or less than about 1.2 wt%, or less than about 1.0 wt%.

6. The dispersion according to any one of claims 1 to 5, characterized in that, The dispersion has a) The total amount of CB particles and CNT particles, approximately 1.5 wt% to approximately 10 wt%; b) When tested using a modular compact rheometer, approximately 1.0 Pa was obtained at a shear rate of 1 Hz. s to approximately 6.8 Pa The viscosity of s; and / or c) A yield stress of at least about 1.0 Pa and at most 26.0 Pa, wherein the yield stress is defined as the intersection of G' and G”.

7. The dispersion according to any one of claims 1 to 6, wherein, The dispersion is characterized by a shear rate of approximately 1.2 Pa at a shear rate of 1 Hz when tested by a modular compact rheometer. s to approximately 6.6 Pa The viscosity of s Optionally, the dispersion is characterized by having a shear rate of approximately 1.4 Pa at 1 Hz when tested by a modular compact rheometer. s to approximately 6.4 Pa The viscosity of s.

8. The dispersion according to any one of claims 1 to 7, wherein, The dispersion is characterized by a yield stress of at least about 1.2 Pa and at most about 24.0 Pa, said yield stress being defined as the intersection of G' and G”. Optionally, the dispersion is characterized by a yield stress of at least about 1.5 Pa and at most about 22.0 Pa, the yield stress being defined as the intersection of G' and G”.

9. The dispersion according to any one of claims 1 to 8, wherein, The dispersion is characterized by a loss modulus (G") ranging from about 0.5 Pa to about 50 Pa and a storage modulus (G') ranging from about 0.5 Pa to about 150 Pa when tested by a modular compact rheometer over a shear stress range of about 0.001 Pa to about 2 Pa. Optionally, the dispersion is characterized by having, when tested by a modular compact rheometer, a loss modulus (G") ranging from about 1 Pa to about 45 Pa and a storage modulus (G') ranging from about 1 Pa to about 140 Pa in the range of shear stress from about 0.001 Pa to about 2 Pa, or a loss modulus (G") ranging from about 2 Pa to about 40 Pa and a storage modulus (G') ranging from about 2 Pa to about 130 Pa.

10. The dispersion according to any one of claims 1 to 9, wherein, The dispersion is characterized by a loss factor tan(δ) of approximately 0.35 to approximately 0.85 when tested by a modular compact rheometer in a shear stress range of approximately 0.001 Pa to approximately 2 Pa, and at a shear stress of 0.1 Pa. Optionally, the dispersion is characterized by a loss factor tan(δ) of about 0.4 to about 0.8, or about 0.45 to about 0.75, when tested by a modular compact rheometer under shear stresses ranging from about 0.001 Pa to about 2 Pa.

11. A cathode paste composition comprising: a) The dispersion according to any one of claims 1 to 10; b) Active lithium materials; c) Dispersion medium; and d) Adhesives.

12. A cathode, wherein, The cathode is produced by applying the cathode slurry composition according to claim 11 onto a substrate and then drying the coated substrate at a temperature of at least 100°C for at least 5 minutes.

13. A lithium-ion battery comprising the cathode according to claim 12.

14. A method for preparing a dispersion, comprising: a) Disperse the dispersant in the solvent; b) Adding carbon black (CB) particles to the solvent, wherein the carbon black is characterized in that... (i) Approximately 40 m 2 / g to approximately 650 m 2 / g of BET SSA; (ii) Oil absorption value (OAN) of approximately 230 mL / 100 g to approximately 400 mL / 100 g. (iii) The ratio of compression absorbance value (cOAN) to OAN (cOAN / OAN) of approximately 0.2 to approximately 0.85; and (iv) Each aggregate contains fewer than approximately 235 primary particles; c) Adding carbon nanotube (CNT) particles to the solvent, wherein the carbon nanotubes are characterized in that... (i) an outer diameter of about 9 nm to about 18 nm; and (ii) D from about 1 μm to about 13 μm 50 length; d) The solvent containing the dispersant, CB particles, and CNT particles is mixed in a mixer. The CNT particles and the CB particles are added to each other at a ratio of approximately 10:1 (w / w) to approximately 1:1 (w / w).

15. The method according to claim 14, wherein, The final dispersion is characterized by a) The total amount of CB particles and CNT particles, approximately 1.5 wt% to approximately 10 wt%; b) When tested using a modular compact rheometer, approximately 1.0 Pa was obtained at a shear rate of 1 Hz. s to approximately 6.8 Pa The viscosity of s, and / or d) A yield stress of at least about 1.0 Pa and at most 26.0 Pa, wherein the yield stress is defined as the intersection of G' and G”.

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