High shear slurry mixing methods and formulations for cathode active material layers
Through the high shear electrode mixing method, the problem of uneven mixing of cathode electrodes is solved, and the efficient manufacturing of cathode electrodes is achieved, reducing costs and improving battery performance.
Patent Information
- Application Number
- CN202410560958.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-02-14
- Filing Date
- 2024-05-08
- Publication Date
- 2025-08-15
AI Technical Summary
In the prior art, when manufacturing cathode electrodes, it is difficult to effectively mix cathode active materials, conductive additives and adhesives, resulting in unstable performance and high cost.
Using a high shear electrode mixing method, a mixture of the cathode active material layer is mixed at a specific temperature and torque using a screw extruder/mixer, followed by a reduction in viscosity through a viscosity reducer and a slurry distributor, and finally the mixture is applied to the cathode current collector to form the electrode.
It realizes efficient mixing of cathode electrodes, reduces the cost of conductive fillers, improves the stability of electrode performance and the electrochemical performance of the battery, and reduces the dependence on high-cost materials.
Smart Images
Figure CN120497291A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to battery cells, and more particularly to a high shear electrode mixing method for cathode electrodes of battery cells. Background Art
[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that work currently named as inventors is described in this section, and with respect to aspects of the specification that may not have otherwise been identified as prior art at the time of filing, no admission is made, either expressly or by implication, that it is prior art with respect to the present disclosure.
[0003] The present disclosure relates to battery cells, and more particularly to a high shear electrode mixing method for cathode electrodes of battery cells.
[0004] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, include one or more electric motors and a battery system comprising one or more battery cells, modules, and / or packs. A power control system is used to control the charging and / or discharging of the battery system during charging and / or driving.
[0005] The battery cell includes one or more cathode electrodes, an anode electrode, and a separator. The cathode electrode includes a cathode active material layer disposed on a cathode current collector. The anode electrode includes an anode active material layer disposed on an anode current collector. Summary of the Invention
[0006] A method for manufacturing a cathode electrode comprises: providing a mixture for a cathode active material layer, the mixture comprising a cathode active material, a conductive additive, a binder, and a solvent; mixing the mixture in an extruder / mixer at a predetermined temperature for a predetermined time period, wherein during the mixing process in the extruder / mixer, the mixture is heated to a temperature of 20s. -1 The viscosity of the mixture is reduced to 20 s after mixing in the extruder / mixer. -1 less than 10 Pascal-seconds (Pa·s) under the conditions of 100 nm; and applying the mixture to a cathode current collector to form a cathode electrode.
[0007] In other features, during mixing in the extruder / mixer, the mixture has a solids content greater than 70%. The extruder / mixer mixes the mixture at a torque greater than or equal to 25 Nm. The extruder / mixer mixes the mixture at a torque in the range of 25 Nm to 30 Nm. The predetermined time period is in the range of 15 to 20 minutes. The predetermined temperature is less than 40° C. The predetermined temperature is in the range of 25° C. to 30° C.
[0008] In other features, the conductive additive comprises particles having a specific surface area greater than 125 m2 / g. The conductive additive comprises particles having a specific surface area greater than 300 m2 / g. The conductive additive is selected from acetylene black and furnace black.
[0009] In other features, the method includes reducing the viscosity of the mixture, including adding a solvent to reduce the viscosity of the mixture to within 20s -1 The binder comprises PVDF. The binder further comprises at least one of a sulfate and a carboxylate dispersant.
[0010] In other features, the cathode active material comprises 90 to 98 weight percent of the cathode active material layer, the conductive additive comprises 0.2 to 6 weight percent of the cathode active material layer, and the binder comprises 0.5 to 5 weight percent of the cathode active material layer. The cathode active material is selected from LFP, LMFP, NMC, NCMA, LMR, and combinations thereof.
[0011] A method for manufacturing a cathode electrode comprises providing a mixture of a cathode active material layer, the mixture comprising a cathode active material, a conductive additive, a binder and a solvent, the conductive additive comprising a specific surface area greater than 125 m 2 The method comprises mixing the mixture in an extruder / mixer at a predetermined temperature for a predetermined period of time, wherein the mixture is mixed in the extruder / mixer for 20 seconds. -1 The mixture is mixed in an extruder / mixer at a torque of 25 Nm or greater and a viscosity of greater than 10 Pascal-seconds (Pa·s) is obtained; after mixing in the extruder / mixer, the viscosity of the mixture is reduced to a value of 0.05 Nm at 20 s. -1 and applying the mixture to a cathode current collector to form a cathode electrode.
[0012] In other features, the predetermined time period is in the range of 15 to 20 minutes. The predetermined temperature is below 40° C. The conductive additive comprises a surface area greater than 300 m 2 / g of particles.
[0013] In other features, the cathode active material comprises 90 to 98 weight percent of the cathode active material layer, the cathode active material is selected from LFP, LMFP, NMC, NCMA, LMR, and combinations thereof, the conductive additive comprises 0.2 to 6 weight percent of the cathode active material layer, and the binder comprises 0.5 to 5 weight percent of the cathode active material layer.
[0014] The present invention discloses the following solutions:
[0015] Solution 1. A method for manufacturing a cathode electrode, comprising:
[0016] providing a mixture for a cathode active material layer comprising a cathode active material, a conductive additive, a binder, and a solvent;
[0017] The mixture is mixed in an extruder / mixer at a predetermined temperature for a predetermined period of time, wherein the mixture is mixed in the extruder / mixer for 20 seconds. -1 having a viscosity greater than 10 Pascal-seconds (Pa·s);
[0018] After mixing in the extruder / mixer, the viscosity of the mixture was reduced to 20s -1 Less than 10 Pascal-seconds (Pa·s) under
[0019] The mixture is applied to a cathode current collector to form a cathode electrode.
[0020] Option 2. The method of Option 1, wherein during mixing in the extruder / mixer, the mixture has a solids content greater than 70%.
[0021] Option 3. The method of Option 1, wherein the extruder / mixer mixes the mixture at a torque greater than or equal to 25 Nm.
[0022] Option 4. The method of Option 1, wherein the extruder / mixer mixes the mixture at a torque in the range of 25 Nm to 30 Nm.
[0023] Option 5. The method of Option 1, wherein the predetermined time period is in the range of 15 to 20 minutes.
[0024] Option 6. The method according to Option 1, wherein the predetermined temperature is below 40°C.
[0025] Option 7. The method according to Option 1, wherein the predetermined temperature is in the range of 25°C to 30°C.
[0026] Option 8. The method according to Option 1, wherein the conductive additive comprises a specific surface area greater than 125 m 2 / g of particles.
[0027] Option 9. The method according to Option 1, wherein the conductive additive comprises a specific surface area greater than 300 m 2 / g of particles.
[0028] Option 10. The method according to Option 8, wherein the conductive additive is selected from acetylene black and furnace black.
[0029] Scheme 11. The method according to Scheme 1, wherein reducing the viscosity of the mixture comprises adding a solvent to reduce the viscosity of the mixture to 20s -1The lower limit is less than 10 Pascal seconds (Pa·s).
[0030] Option 12. The method of Option 1, wherein the adhesive comprises PVDF.
[0031] Item 13. The method of item 12, wherein the binder further comprises at least one of a sulfate and a carboxylate dispersant.
[0032] 14. The method according to claim 1, wherein:
[0033] The cathode active material accounts for 90 to 98 weight percent of the cathode active material layer,
[0034] The conductive additive accounts for 0.2 to 6 weight percent of the cathode active material layer, and
[0035] The binder accounts for 0.5 to 5 weight percent of the cathode active material layer.
[0036] Option 15. The method according to Option 1, wherein the cathode active material is selected from LFP, LMFP, NMC, NCMA, LMR and combinations thereof.
[0037] Solution 16. A method for manufacturing a cathode electrode, comprising:
[0038] providing a mixture for a cathode active material layer comprising a cathode active material, a conductive additive, a binder, and a solvent,
[0039] The conductive additive includes a specific surface area greater than 125m 2 / g of particles;
[0040] The mixture is mixed in an extruder / mixer at a predetermined temperature for a predetermined period of time, wherein the mixture is mixed in the extruder / mixer for 20 seconds. -1 having a viscosity greater than 10 Pascal-seconds (Pa·s) at a temperature of 100°C and a temperature of 100°C, and the extruder / mixer mixes the mixture at a torque greater than or equal to 25 Nm;
[0041] After mixing in the extruder / mixer, the viscosity of the mixture was reduced to 20s -1 Less than 10 Pascal-seconds (Pa·s) under
[0042] The mixture is applied to a cathode current collector to form a cathode electrode.
[0043] Option 17. The method of Option 16, wherein the predetermined time period is in the range of 15 to 20 minutes.
[0044] Option 18. The method according to Option 16, wherein the predetermined temperature is below 40°C.
[0045] Option 19. The method according to Option 16, wherein the conductive additive comprises a specific surface area greater than 300 m 2 / g of particles.
[0046] Item 20. The method of item 16, wherein:
[0047] The cathode active material accounts for 90 to 98 weight percent of the cathode active material layer,
[0048] The cathode active material is selected from LFP, LMFP, NMC, NCMA, LMR and combinations thereof,
[0049] The conductive additive accounts for 0.2 to 6 weight percent of the cathode active material layer, and
[0050] The binder accounts for 0.5 to 5 weight percent of the cathode active material layer.
[0051] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings.The detailed description and specific examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0052] The present disclosure will be more fully understood through the detailed description and accompanying drawings, in which:
[0053] Figure 1 is a cross-sectional view of one example of a battery cell including an anode electrode, a cathode electrode, and a separator according to the present disclosure;
[0054] Figure 2 is a cross-sectional view of an example of a cathode electrode according to the present disclosure;
[0055] Figure 3A is a cross-sectional view of an example of a method for manufacturing a cathode electrode using high shear mixing according to the present disclosure;
[0056] Figure 3B and Figure 3C are examples of visbreakers and slurry distributors according to the present disclosure;
[0057] Figure 4A An example of how the discharge specific capacity of cathode electrodes manufactured using a conventional method and the high shear electrode mixing method according to the present disclosure changes with the number of cycles is shown;
[0058] Figure 4BAn example of the capacity retention percentage of cathode electrodes manufactured using a conventional method and a high shear electrode mixing method according to the present disclosure as a function of cycle number is shown;
[0059] Figure 5A An example of how the discharge capacity retention of cathode electrodes manufactured using a conventional method and the high shear electrode mixing method according to the present disclosure varies with the number of cycles is shown; and
[0060] Figure 5B Examples of capacity variation with cycle number at different discharge rates for cathode electrodes manufactured using conventional methods and the high shear electrode mixing method according to the present disclosure are shown.
[0061] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION
[0062] Although battery cells according to the present disclosure are shown in the context of electric vehicles, battery cells may also be used in stationary applications and / or other applications.
[0063] The present disclosure relates to a high shear electrode mixing method for manufacturing a cathode active material layer of a cathode electrode. The high shear electrode mixing method uses a screw extruder / mixer that provides high shear / torque. In some examples, the mixture of the cathode active material layer includes one or more cathode active materials, a conductive additive, a binder, and a solvent. In some examples, the mixture has a solid content greater than 70%. For active materials with higher specific surface areas (i.e., LFP), the solid content is in the range of 70% to 85%. In some examples, the conductive additive includes a cathode active material with a high specific surface area (e.g., greater than 125 m 2 Specific surface area (SSA) is a property of solids and is defined as the total surface area (SA) per unit mass of the material.
[0064] Among other advantages, the high shear electrode mixing method allows the elimination of carbon nanotubes (CNTs) from the conductive filler in the cathode active material layer without sacrificing performance. The cost of CNTs is 5 to 200 times that of other less expensive conductive fillers, such as acetylene black (AB) or furnace black (FB). The kneading process at high solids content can grind the initial agglomerate structure of the carbon black, and the growth of the agglomerates after grinding is then limited by the limited particle mobility at high solids content, thereby effectively dispersing the conductive carbon throughout the electrode layer.
[0065] In some examples, the mixture of the cathode active material layer is mixed / sheared in a screw extruder / mixer at high shear / torque (e.g., in the range of 25 Nm to 30 Nm) for a predetermined mixing period (e.g., 15 to 20 minutes). In some examples, the viscosity of the mixture during mixing is between 20s -1 The lower limit is greater than 10 Pascal-seconds (Pa·s).
[0066] In some examples, the mixing chamber of the screw extruder / mixer is at least 75% full during mixing. In some examples, the temperature is below 40° C. (e.g., 25° C. to 30° C.) during operation. In some examples, the specific energy input is in the range of 0.4 to 0.5 kJ / g material.
[0067] In some examples, the output of the screw extruder / mixer feeds a visbreaker and slurry distributor comprising a slot die at its output. In some examples, the visbreaker and slurry distributor are configured to add additional solvent to reduce the viscosity of the extruded cathode active material layer to within 20s before casting. -1 The pressure below is less than 10Pa·s.
[0068] Now refer to Figure 1 The battery cell 10 includes C cathode electrodes 20, A anode electrodes 40, and S separators 32 arranged in a predetermined order in the battery cell stack 12, where C, S, and A are integers greater than zero. The C cathode electrodes 20-1, 20-2, ..., and 20-C include a cathode active material layer 24 arranged on one or both sides of a cathode current collector 26. The A anode electrodes 40-1, 40-2, ..., and 40-A include an anode active material layer 42 arranged on one or both sides of an anode current collector 46. During the charge / discharge process, the A anode electrodes 40 and the C cathode electrodes 20 exchange lithium ions.
[0069] In some examples, cathode active material layer 24 comprises an extrusion including one or more active materials, one or more conductive additives, and / or one or more binder materials that is cast onto a cathode current collector (eg, using a wet roll-to-roll process).
[0070] In some examples, the cathode current collector 26 and / or the anode current collector 46 include metal foil, metal mesh, perforated metal, three-dimensional (3D) metal foam and / or expanded metal. In some examples, the current collector is made of one or more materials selected from copper, stainless steel, brass, bronze, zinc, aluminum and / or their alloys. External tabs 28 and 48 are connected to the current collectors of the cathode electrode and the anode electrode, respectively, and can be arranged on the same side or different sides of the battery cell stack 12. External tabs 28 and 48 are connected to the terminals of the battery cells.
[0071] Now refer to Figure 2 , further details are shown for C cathode electrodes 20. The cathode active material layer 24 of the C cathode electrodes 20 includes a cathode active material 62, a conductive additive 64, and a binder 66. The cathode active material layer 24 is extruded using the high shear electrode mixing method described herein.
[0072] In some examples, the cathode active material accounts for 90 wt % to 98 wt % of the cathode active material layer, the conductive filler accounts for 0.2 wt % to 6 wt % of the cathode active material layer, and the binder accounts for 0.5 wt % to 5 wt % of the cathode active material layer. In some examples, the cathode active material includes lithium iron phosphate (LFP) material, lithium manganese iron phosphate (LMFP) material, lithium nickel manganese carbon (NMC) material, lithium nickel carbon manganese aluminum (NCMA) material, lithium-rich and manganese-rich (LMR) material, and combinations thereof.
[0073] In some embodiments, the conductive filler comprises a surface area greater than 125 m 2 In some examples, the conductive filler includes particles having a certain specific surface area (e.g., greater than 125, 200, or 300 m 2 / g) of acetylene black (AB) or furnace black. In some examples, the binder includes polyvinylidene fluoride (PVDF). In some examples, the binder further includes an optional sulfate and / or carboxylate dispersant.
[0074] Now refer to Figures 3A to 3C , shows the use of a high shear electrode mixing method to make a cathode active material layer and further processing the cathode active material layer into a cathode electrode. Figure 3A In the process, cathode active material 110, conductive additive 114, and binder 116 are fed to inlet 120 of extruder / mixer 118 (via optional hopper 119).
[0075] The extruder / mixer 118 includes an elongated cavity 122. A screw 123 including a shaft 124 having an inclined plane 126 is positioned within the elongated cavity 122 and configured to rotate. The screw 123 moves / mixes the mixture through the elongated cavity 122. One or more inlets 134 are positioned along the extruder / mixer 118 to allow solvent to be added to the elongated cavity 122 at one or more lateral locations, as needed, to control or adjust viscosity.
[0076] The mixed and sheared cathode active material from the extruder / mixer 118 is output to a viscosity reducer and slurry distributor 136. The viscosity reducer and slurry distributor 136 includes a slot die 137 at its output end that acts as a slurry distributor. The viscosity reducer and slurry distributor 136 receives the mixture and adds additional solvent to the mixture to reduce the viscosity of the mixture for the cathode active material layer.
[0077] exist Figure 3B In one example of a viscosity reducer and slurry distributor 136, another extruder / mixer 118' is included that adds additional solvent to the mixture to reduce the viscosity. Figure 3C In one embodiment, a viscosity reducer and slurry distributor 136 includes a conduit 139 that receives the mixture from the extruder / mixer 118. The conduit 139 is disposed in the slurry reservoir 140. The conduit 139 includes one or more inlets or holes for receiving a solvent to reduce the viscosity of the mixture before the mixture passes through the slot die 137 and is further processed. In some examples, the solvent is supplied by a pipeline that supplies the solvent under high pressure.
[0078] The reduced viscosity active material layer 141 is fed through a slot die (or using a reverse comma method) and between a pair of rollers 142 and 143. Roller 144 provides a layer such as a current collector 148 between the pair of rollers 142 and 143. In some examples, roller 149 provides an optional release layer 150 between the pair of rollers 142 and 143. The current collector 148, the extruded active material layer 141, and the optional release layer 150 may optionally pass through one or more guide rollers 152 before being fed between rollers 154 and 156. The optional release layer 150 may be removed and collected on a roll 158.
[0079] The current collector 148 and the extruded active material layer 141 pass through an oven operating at a temperature within a predetermined range to dry the extruded mixture (e.g., to remove the solvent). The current collector 148 and the extruded active material layer 141 are dried in the oven and then guided between rollers 164 and 166, passed through an optional guide roller 170, and pressed and / or heated to a predetermined thickness and / or porosity by rollers 174 and 176. After passing through rollers 174 and 176, the cathode electrode 177 comprising the current collector 148 and the extruded active material layer 141 is collected on a roll 180.
[0080] Now refer to Figure 4A and Figure 4B, shows the performance of various conductive filler examples for a battery cell comprising a graphite anode electrode and a cathode comprising NCMA and LMFP (70:30) with a PVDF binder at 80% solids. The electrolyte comprises 1M LiPF6 in ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) (1:1:1 ratio), 0.5 wt% vinyl ethylene carbonate, 1.0 wt% vinyl carbonate, and 1.5 wt% propane sultone.
[0081] The first example at 143 includes a conductive filler comprising carbon black, 2D graphene nanosheets (GNPs) and 1D single-walled carbon nanotubes (SWCNTs) (e.g., at 0.8 wt%, 0.6 wt% and 0.1 wt%). The second example at 145 includes a conductive filler comprising carbon black and SWCNTs (e.g., at 1.4 wt% and 0.1 wt%). The third example at 146 includes a conductive filler comprising acetylene black (e.g., at 1.5 wt%) mixed with high shear as described herein. It can be seen that the third example 146 without SWCNTs performs well. Therefore, high shear mixing according to the present disclosure can be used to eliminate CNTs, thereby reducing the cost of cathode electrodes without sacrificing performance. In addition, by effectively mixing a formulation with high surface area acetylene black (AB), stable battery electrochemical performance can be achieved.
[0082] Now refer to Figure 5A and Figure 5B , shows the performance of examples made using conventional mixing methods (at 210) and the high shear mixing method described herein (at 220). In this example, the anode electrode comprises 5.5% SiOx-graphite. The high shear mixing example comprises a cathode active material layer of 97 wt% NCMA-LMFP (70:30), 1.5 wt% of a high specific surface area (e.g., greater than 125 m 2 / g) of acetylene black, and 1.5 wt% PVDF. A conventional method example includes 97 wt% NCMA-LMFP (70:30), 0.8 wt% SuperP, 0.6 wt% GNPs, 0.1 wt% 1D CNTs, 1.2 wt% PVDF, and 0.3 wt% acetylene black.
[0083] exist Figure 5A In the example, the electrolyte includes 1M LiPF6 in EC:DMC (3:7), 2% fluoroethylene carbonate (FEC) and 1% vinylene carbonate (VC). It can be seen that the discharge capacity retention percentage of the high shear mixing example at 220 is greater than that of the conventional method example at 210. Figure 5BIn the example, the electrolyte includes 1M LiPF6 in EC:DMC (3:7) and 1% lithium difluorooxalatoborate (LiDFOB). It can be seen that for different discharge rates, the capacity of the high shear mixing example at 220 is approximately equal to or greater than that of the conventional method example at 210.
[0084] The foregoing description is merely exemplary in nature and is absolutely not intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be limited thereto, because after studying the drawings, the description and the following claims, other modifications will become apparent. It should be understood that one or more steps within the method may be implemented in a different order (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more features described with respect to any embodiment of the present disclosure may be implemented in any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and the mutual replacement of one or more embodiments is still within the scope of the present disclosure.
[0085] Various terms are used to describe spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "over," "under," and "disposed." Unless explicitly described as "directly," when describing a relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship with no other intervening elements between the first element and the second element, or an indirect relationship with one or more intervening elements between the first element and the second element (spatially or functionally). As used herein, the phrase "at least one of A, B, and C" should be interpreted to mean a logical, non-exclusive logical OR (A OR B OR C) and should not be interpreted to mean "at least one A, at least one B, and at least one C."
Claims
1. A method for manufacturing a cathode electrode, comprising: providing a mixture for a cathode active material layer comprising a cathode active material, a conductive additive, a binder, and a solvent; The mixture is mixed in an extruder / mixer at a predetermined temperature for a predetermined period of time, wherein the mixture is mixed in the extruder / mixer for 20 seconds. -1 having a viscosity greater than 10 Pascal-seconds (Pa·s); After mixing in the extruder / mixer, the viscosity of the mixture was reduced to 20s -1 Less than 10 Pascal-seconds (Pa·s) under The mixture is applied to a cathode current collector to form a cathode electrode.
2. The method of claim 1, wherein during mixing in the extruder / mixer, the mixture has a solids content greater than 70%.
3. The method of claim 1, wherein the extruder / mixer mixes the mixture at a torque greater than or equal to 25 Nm.
4. The method of claim 1, wherein the extruder / mixer mixes the mixture at a torque in the range of 25 Nm to 30 Nm. The method of claim 1 , wherein the predetermined period of time is in the range of 15 to 20 minutes. The method according to claim 1 , wherein the predetermined temperature is below 40° C. 7 . The method according to claim 1 , wherein the predetermined temperature is in the range of 25° C. to 30° C.
8. The method of claim 1, wherein the conductive additive comprises a surface area greater than 125 m 2 / g of particles.
9. The method of claim 1, wherein the conductive additive comprises a surface area greater than 300 m 2 / g of particles.
10. The method of claim 8, wherein the conductive additive is selected from acetylene black and furnace black.