A high-power energy storage battery cell and its preparation method

Abstract

The present invention relates to the field of energy storage devices, and discloses a high-power energy storage battery cell and a preparation method thereof, comprising a stacked positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet being separated by a diaphragm; the positive electrode sheet comprising a positive electrode current collector and a battery material layer and a capacitor material layer respectively arranged on both sides of the positive electrode current collector; the capacitor material layer comprising an inner layer bonded to the positive electrode current collector and an outer layer arranged on the inner layer; the components of the inner layer comprising a capacitor material, a conductive agent and a PVDF binder; the components of the outer layer comprising a capacitor material, a conductive agent and PEDOT:PSS; the components of the battery material layer comprising a battery positive electrode material, a conductive agent, an SBR binder and a CMC binder. The present invention coats the battery material and the capacitor material on both sides of the positive electrode current collector, respectively, which can effectively avoid the problem of a low discharge voltage platform caused by the incompatibility between the battery type material and the capacitor type material, and effectively improves the energy density of the device while ensuring the high power density of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage devices, and in particular to a high-power energy storage battery cell and a preparation method thereof. Background Art

[0002] Renewable energy sources such as wind and light are easily affected by external conditions and require suitable energy storage devices to store them in a timely and efficient manner. Lithium-ion batteries have the advantages of high energy density and a wide operating voltage range, making them a research hotspot for new energy storage devices. However, due to the influence of battery internal resistance and polarization, the battery voltage drops rapidly under high power density conditions, greatly limiting its scope of use. Among high-power energy storage devices, supercapacitors have become the first choice among many energy storage devices due to their advantages such as long cycle life, high power density and wide operating temperature range. However, their low energy density, low operating voltage and large self-discharge also limit their application potential.

[0003] The development of energy storage devices that take into account both high energy density / power density and long cycle life can meet the application requirements of long endurance, high mobility, high power output and other scenarios in the fields of grid frequency modulation, special equipment, etc. High-power energy storage devices in the prior art generally coat a mixture of battery-type materials and capacitor-type materials on a current collector as a positive electrode sheet, which is then assembled with the corresponding negative electrode sheet. For example, a battery capacitor disclosed in patent CN106159232A, the battery cell is assembled by stacking a positive electrode sheet, a diaphragm and a negative electrode sheet, the positive electrode sheet includes a current collector and a positive electrode material formed on the surface of the current collector, and the positive electrode material is mainly composed of a composite of lithium-ion battery positive electrode material and supercapacitor electrode material. However, due to the incompatibility of battery-type materials and capacitor-type materials, directly mixing and coating the two will cause the discharge voltage platform of the overall device to be significantly lower than the charging voltage platform, affecting the rate performance and energy density.

[0004] Patent CN111987392A discloses a separate lithium-ion battery capacitor and its preparation method. The lithium-ion battery material in the positive electrode sheet is not directly mixed with the supercapacitor material. The lithium-ion battery material and the supercapacitor material are made into battery electrodes (positive electrode sheets loaded with lithium-ion battery materials) and capacitor electrodes (positive electrode sheets loaded with supercapacitor materials) respectively, and then connected in parallel. In this way, the internal parallel design of the lithium-ion battery material and the supercapacitor material is realized, while the mutual influence between the two electrode materials is avoided. However, making the battery material and the capacitor material into electrodes separately will increase the amount of current collector and diaphragm in the battery cell, increase the redundant interface layer, increase the charge transfer path, and reduce the volume energy density of the capacitor. Summary of the Invention

[0005] The present invention aims to overcome the above-mentioned problems existing in high-power energy storage devices in the prior art that contain both battery materials and capacitor materials, and provides a high-power energy storage battery cell and a preparation method thereof. Battery materials and capacitor materials are coated on both sides of the positive electrode current collector respectively, which can effectively avoid the problem of low discharge voltage platform caused by incompatibility between battery-type materials and capacitor-type materials, and effectively improve the energy density of the device while ensuring high power density of the device.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A high-power energy storage battery cell, comprising a stacked positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet being separated by a separator;

[0008] The positive electrode sheet includes a positive electrode current collector and a battery material layer and a capacitor material layer respectively arranged on both sides of the positive electrode current collector;

[0009] The capacitor material layer includes an inner layer attached to the positive electrode current collector and an outer layer arranged on the inner layer; the components of the inner layer include capacitor material, conductive agent and PVDF binder; the components of the outer layer include capacitor material, conductive agent and PEDOT:PSS;

[0010] The components of the battery material layer include battery positive electrode material, conductive agent, SBR binder and CMC binder;

[0011] The negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer arranged on both sides of the negative electrode current collector; the components of the negative electrode material layer include a negative electrode material, a conductive agent and a binder.

[0012] The present invention coats battery materials and capacitor materials on both sides of the positive electrode current collector, respectively, which can effectively avoid the problem of low discharge voltage platform caused by incompatibility between battery-type materials and capacitor-type materials, and effectively improve the energy density of the device while ensuring high power density of the device.

[0013] However, coating battery materials and capacitor materials on both sides of the positive electrode current collector has the following problems: 1. Battery materials rely on ion insertion / deinsertion reactions, and the reaction kinetics are slow, while capacitor materials rely on rapid adsorption / desorption of the double layer, and the response speed is in the millisecond level; when the two work on the same current collector, the difference in charge and discharge rates will lead to uneven internal current distribution, aggravating polarization and reducing overall efficiency. 2. Battery materials will expand during charging and discharging. Although the positive electrode material expands less than the negative electrode material, there is still a large difference in the expansion degree between the two compared with the capacitor material with almost zero expansion. When the battery material and capacitor material are coated on both sides of the positive electrode current collector, the inconsistent repeated expansion / contraction on both sides will generate shear stress, causing the coating to peel off. To address the above problems, the present invention adds a conductive polymer PEDOT:PSS to the capacitor material layer, which can accelerate interfacial charge transfer, efficiently dispatch charge flow to the slow-responding battery material layer, and reduce the response lag difference with the battery material. At the same time, the present invention uses a highly elastic binder SBR in the battery material layer and a rigid binder PVDF in the capacitor material layer, which can alleviate the shear stress caused by the expansion difference on both sides and reduce the risk of coating peeling.

[0014] Preferably, in the capacitor material layer, the mass ratio of the capacitor material in the inner layer to that in the outer layer is 2-4:1.

[0015] Preferably, in the inner layer of the capacitor material layer, the mass ratio of the capacitor material, the conductive agent and the PVDF binder is 85~95:5~10:5; in the outer layer of the capacitor material layer, the mass ratio of the capacitor material, the conductive agent and PEDOT:PSS is 50~60:5~10:5.

[0016] Preferably, in the battery material layer, the mass ratio of the battery positive electrode material, the conductive agent, the SBR binder and the CMC binder is 80-90:5-10:2-3:2.

[0017] Preferably, the mass ratio of the battery positive electrode material in the battery material layer to the capacitor material in the capacitor material layer is 0.5-2:1.

[0018] Preferably, in the negative electrode material layer, the mass ratio of the negative electrode material, the conductive agent, and the binder is 80-90:5-10:6-8.

[0019] Preferably, the battery positive electrode material is selected from one or more of lithium battery positive electrode materials and nickel-metal hydride battery positive electrode materials.

[0020] Preferably, the capacitor material is selected from one or more of capacitor carbon materials and transition metal oxides.

[0021] Preferably, the negative electrode material is selected from one or more lithium-intercalated carbon-based materials.

[0022] Preferably, the binder in the negative electrode material layer is selected from one or more of PVDF, SBR, CMC, and polyacrylic acid.

[0023] Preferably, the conductive agent is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotubes, and graphene.

[0024] The present invention also provides a method for preparing the above-mentioned high-power energy storage battery cell, comprising the following steps:

[0025] (1) The components of the inner layer and the outer layer are made into a slurry and coated on one side of the positive electrode current collector in sequence, and dried to obtain a capacitor material layer;

[0026] (2) The components of the battery material layer are made into a slurry and then coated on the other side of the positive electrode current collector. After drying, the slurry is rolled and punched to obtain a positive electrode sheet;

[0027] (3) The components of the negative electrode material layer are made into a slurry and then coated on both sides of the negative electrode current collector. After drying, the slurry is rolled and punched to obtain a negative electrode sheet;

[0028] (4) Assemble the positive electrode sheet, negative electrode sheet and separator into a high-power energy storage cell by stacking them.

[0029] Therefore, the present invention has the following beneficial effects:

[0030] (1) Coating battery materials and capacitor materials on both sides of the positive electrode current collector can effectively avoid the problem of low discharge voltage platform caused by incompatibility between battery materials and capacitor materials, and effectively improve the energy density of the device while ensuring high power density of the device;

[0031] (2) Adding the conductive polymer PEDOT:PSS to the capacitor material layer can accelerate the interfacial charge transfer, efficiently dispatch the charge flow to the slow-responding battery material layer, and reduce the response hysteresis difference with the battery material;

[0032] (3) Using a highly elastic binder SBR in the battery material layer and a rigid binder PVDF in the capacitor material layer can alleviate the shear stress caused by the expansion difference on both sides and reduce the risk of coating peeling. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific embodiments.

[0034] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0035] Overall embodiment:

[0036] A high-power energy storage battery cell, comprising a stacked positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet being separated by a separator;

[0037] The positive electrode sheet includes a positive electrode current collector and a battery material layer and a capacitor material layer respectively arranged on both sides of the positive electrode current collector;

[0038] The capacitor material layer includes an inner layer attached to the positive electrode current collector and an outer layer arranged on the inner layer; the components of the inner layer include capacitor material, conductive agent and PVDF binder; the components of the outer layer include capacitor material, conductive agent and PEDOT:PSS;

[0039] The components of the battery material layer include battery positive electrode material, conductive agent, SBR binder and CMC binder;

[0040] The negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer arranged on both sides of the negative electrode current collector; the components of the negative electrode material layer include a negative electrode material, a conductive agent and a binder.

[0041] As a specific implementation manner, in the capacitor material layer, the mass ratio of the capacitor material in the inner layer to that in the outer layer is 2-4:1.

[0042] As a specific embodiment, in the inner layer of the capacitor material layer, the mass ratio of the capacitor material, the conductive agent and the PVDF binder is 85~95:5~10:5; in the outer layer of the capacitor material layer, the mass ratio of the capacitor material, the conductive agent and PEDOT:PSS is 50~60:5~10:5.

[0043] As a specific embodiment, in the battery material layer, the mass ratio of the battery positive electrode material, the conductive agent, the SBR binder and the CMC binder is 80~90:5~10:2~3:2.

[0044] As a specific implementation manner, the mass ratio of the battery positive electrode material in the battery material layer to the capacitor material in the capacitor material layer is 0.5~2:1.

[0045] As a specific embodiment, in the negative electrode material layer, the mass ratio of the negative electrode material, the conductive agent, and the binder is 80-90:5-10:6-8.

[0046] As a specific embodiment, the battery positive electrode material is selected from one or more of lithium battery positive electrode materials and nickel-hydrogen battery positive electrode materials.

[0047] As a specific embodiment, the lithium battery positive electrode material is selected from one or more of layered structure positive electrode materials, spinel structure positive electrode materials, and olivine structure positive electrode materials; preferably, the lithium battery positive electrode material is selected from one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and lithium iron phosphate.

[0048] As a specific embodiment, the positive electrode material of the nickel-hydrogen battery is Ni(OH)2‌.

[0049] As a specific embodiment, the capacitor material is selected from one or more of capacitor carbon materials and transition metal oxides; preferably, the capacitor material is selected from one or more of activated carbon, activated carbon fiber, carbon gel, carbide derivatives, and transition metal oxides.

[0050] As a specific embodiment, the negative electrode material is selected from one or more lithium-intercalated carbon-based materials; preferably, the negative electrode material is selected from one or more hard carbon, soft carbon, graphite, metal compounds and alloy materials.

[0051] As a specific embodiment, the binder in the negative electrode material layer is selected from one or more of PVDF, SBR, CMC, and polyacrylic acid.

[0052] As a specific embodiment, the conductive agent is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotubes, and graphene.

[0053] As a specific embodiment, the diaphragm is selected from one of polypropylene film, polytetrafluoroethylene film, cellulose film, and polyethylene film, and the thickness of the diaphragm is 10-50 μm.

[0054] The method for preparing the above-mentioned high-power energy storage battery cell comprises the following steps:

[0055] (1) The components of the inner layer and the outer layer are made into a slurry and coated on one side of the positive electrode current collector in sequence, and dried to obtain a capacitor material layer;

[0056] (2) The components of the battery material layer are made into a slurry and then coated on the other side of the positive electrode current collector. After drying, the slurry is rolled and punched to obtain a positive electrode sheet;

[0057] (3) The components of the negative electrode material layer are made into a slurry and then coated on both sides of the negative electrode current collector. After drying, the slurry is rolled and punched to obtain a negative electrode sheet;

[0058] (4) Assemble the positive electrode sheet, negative electrode sheet and separator into a high-power energy storage cell by stacking them.

[0059] As a specific implementation, the drying temperature in step (1) is 70-100° C., and the drying time is 2-8 hours.

[0060] As a specific implementation, the drying temperature in step (2) is 50-90° C., and the drying time is 1-2 hours.

[0061] As a specific implementation manner, the drying temperature in step (3) is 50-120° C., and the drying time is 1-8 hours.

[0062] Example 1:

[0063] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0064] (1) Add Kuraray activated carbon YP-50F, conductive agent SP and PVDF binder into solvent NMP at a mass ratio of 90:10:5, stir and disperse evenly to obtain inner layer slurry; add Kuraray activated carbon YP-50F, conductive agent SP and PEDOT:PSS into water at a mass ratio of 55:10:5, stir and disperse evenly to obtain outer layer slurry;

[0065] (2) Aluminum foil was used as the positive electrode current collector. The inner layer slurry was first coated on one side of the aluminum foil, and then the outer layer slurry was coated on the inner layer slurry. After drying at 80°C for 4 hours, a capacitor material layer was obtained on the surface of the positive electrode current collector. The mass ratio of Kuraray activated carbon YP-50F in the inner layer and the outer layer was 3:1, and the total coating amount of Kuraray activated carbon YP-50F was 200g / m 2 ;

[0066] (3) The ternary positive electrode material lithium nickel cobalt manganese oxide, conductive agent SP, SBR binder and CMC binder are added to water in a mass ratio of 85:10:3:2, and stirred and dispersed evenly to obtain a battery material layer slurry; the battery material layer slurry is coated on the other side of the aluminum foil, and dried at 60°C for 2 hours to obtain a battery material layer on the surface of the positive electrode current collector; then, the positive electrode sheet is obtained by rolling and punching; the mass ratio of the ternary positive electrode material lithium nickel cobalt manganese oxide in the battery material layer and the Kuraray activated carbon YP-50F in the capacitor material layer is 1:1;

[0067] (4) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0068] (5) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage battery cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0069] Example 2:

[0070] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0071] (1) Add Kuraray activated carbon YP-50F, conductive agent SP and PVDF binder into solvent NMP at a mass ratio of 85:5:5, stir and disperse evenly to obtain inner layer slurry; add Kuraray activated carbon YP-50F, conductive agent SP and PEDOT:PSS into water at a mass ratio of 50:5:5, stir and disperse evenly to obtain outer layer slurry;

[0072] (2) Aluminum foil was used as the positive electrode current collector. The inner layer slurry was first coated on one side of the aluminum foil, and then the outer layer slurry was coated on the inner layer slurry. After drying at 100°C for 2 hours, a capacitor material layer was obtained on the surface of the positive electrode current collector. The mass ratio of Kuraray activated carbon YP-50F in the inner layer and the outer layer was 4:1, and the total coating amount of Kuraray activated carbon YP-50F was 200g / m 2 ;

[0073] (3) The ternary positive electrode material lithium nickel cobalt manganese oxide, conductive agent SP, SBR binder and CMC binder are added to water in a mass ratio of 90:5:2:2, and stirred and dispersed evenly to obtain a battery material layer slurry; the battery material layer slurry is coated on the other side of the aluminum foil, and dried at 50°C for 2 hours to obtain a battery material layer on the surface of the positive electrode current collector; then, the positive electrode sheet is obtained by rolling and punching; the mass ratio of the ternary positive electrode material lithium nickel cobalt manganese oxide in the battery material layer to the Kuraray activated carbon YP-50F in the capacitor material layer is 0.5:1;

[0074] (4) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0075] (5) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage battery cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0076] Example 3:

[0077] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0078] (1) Add Kuraray activated carbon YP-50F, conductive agent SP and PVDF binder into solvent NMP at a mass ratio of 90:10:5, stir and disperse evenly to obtain inner layer slurry; add Kuraray activated carbon YP-50F, conductive agent SP and PEDOT:PSS into water at a mass ratio of 55:10:5, stir and disperse evenly to obtain outer layer slurry;

[0079] (2) Aluminum foil was used as the positive electrode current collector. The inner layer slurry was first coated on one side of the aluminum foil, and then the outer layer slurry was coated on the inner layer slurry. After drying at 80°C for 4 hours, a capacitor material layer was obtained on the surface of the positive electrode current collector. The mass ratio of Kuraray activated carbon YP-50F in the inner layer and the outer layer was 2:1, and the total coating amount of Kuraray activated carbon YP-50F was 200g / m 2 ;

[0080] (3) Lithium iron phosphate, conductive agent SP, SBR binder and CMC binder were added to water in a mass ratio of 85:10:3:2, and stirred and dispersed evenly to obtain a battery material layer slurry; the battery material layer slurry was coated on the other side of the aluminum foil, and dried at 60°C for 2 hours to obtain a battery material layer on the surface of the positive electrode current collector; then, the positive electrode sheet was obtained by rolling and punching; the mass ratio of lithium iron phosphate in the battery material layer to Kuraray activated carbon YP-50F in the capacitor material layer was 2:1;

[0081] (4) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0082] (5) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage battery cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0083] Comparative Example 1 (mixed coating of activated carbon and lithium nickel cobalt manganese oxide):

[0084] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0085] (1) Add Kuraray activated carbon YP-50F, ternary cathode material lithium nickel cobalt manganese oxide, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 45:45:10:5, and stir and disperse uniformly to obtain a cathode slurry;

[0086] (2) Aluminum foil is used as the positive electrode current collector. The positive electrode slurry is coated on both sides of the aluminum foil. The single-side coating amount of Kuraray activated carbon YP-50F is 100g / m 2 After drying at 80°C for 4 hours, a positive electrode material layer is obtained on the surface of the positive electrode current collector; the positive electrode sheet is then obtained by roller pressing and punching;

[0087] (3) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0088] (4) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0089] Comparative Example 2 (mixed coating of activated carbon and lithium iron phosphate):

[0090] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0091] (1) Add Kuraray activated carbon YP-50F, lithium iron phosphate, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 60:30:10:5, stir and disperse evenly to obtain a positive electrode slurry;

[0092] (2) Aluminum foil is used as the positive electrode current collector. The positive electrode slurry is coated on both sides of the aluminum foil. The single-side coating amount of Kuraray activated carbon YP-50F is 100g / m 2 After drying at 80°C for 4 hours, a positive electrode material layer is obtained on the surface of the positive electrode current collector; the positive electrode sheet is then obtained by roller pressing and punching;

[0093] (3) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0094] (4) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0095] Comparative Example 3 (no PEDOT:PSS added to the capacitor material layer):

[0096] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0097] (1) Add Kuraray activated carbon YP-50F, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 90:10:5, stir and disperse evenly to obtain capacitor material layer slurry;

[0098] (2) Aluminum foil was used as the positive electrode current collector, and the capacitor material layer slurry was coated on one side of the aluminum foil. After drying at 80°C for 4 hours, the capacitor material layer was obtained on the positive electrode current collector surface. The coating amount of Kuraray activated carbon YP-50F was 200g / m 2 ;

[0099] (3) The ternary positive electrode material lithium nickel cobalt manganese oxide, conductive agent SP, SBR binder and CMC binder are added to water in a mass ratio of 85:10:3:2, and stirred and dispersed evenly to obtain a battery material layer slurry; the battery material layer slurry is coated on the other side of the aluminum foil, and dried at 60°C for 2 hours to obtain a battery material layer on the surface of the positive electrode current collector; then, the positive electrode sheet is obtained by rolling and punching; the mass ratio of the ternary positive electrode material lithium nickel cobalt manganese oxide in the battery material layer and the Kuraray activated carbon YP-50F in the capacitor material layer is 1:1;

[0100] (4) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0101] (5) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage battery cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0102] Comparative Example 4 (adding PEDOT:PSS to the battery material layer):

[0103] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0104] (1) Kuraray activated carbon YP-50F, conductive agent SP and PVDF binder were added to solvent NMP in a mass ratio of 90:10:5, and stirred and dispersed evenly to obtain capacitor material layer slurry; aluminum foil was used as the positive electrode current collector, and the capacitor material layer slurry was coated on one side of the aluminum foil. After drying at 80°C for 4 hours, a capacitor material layer was obtained on the surface of the positive electrode current collector; the coating amount of Kuraray activated carbon YP-50F was 200g / m 2 ;

[0105] (2) Adding the ternary positive electrode material lithium nickel cobalt manganese oxide, conductive agent SP, SBR binder and CMC binder into water at a mass ratio of 85:10:3:2, stirring and dispersing them uniformly to obtain an inner layer slurry; adding the ternary positive electrode material lithium nickel cobalt manganese oxide, conductive agent SP and PEDOT:PSS into water at a mass ratio of 55:10:5, stirring and dispersing them uniformly to obtain an outer layer slurry;

[0106] (3) First, the inner layer slurry is coated on the other side of the aluminum foil, and then the outer layer slurry is coated on the inner layer slurry. After drying at 60°C for 2 hours, a battery material layer is obtained on the surface of the positive electrode current collector; then, the positive electrode sheet is obtained by rolling and punching; the mass ratio of the ternary positive electrode material lithium nickel cobalt manganese oxide in the inner layer and the outer layer is 3:1, and the mass ratio of the ternary positive electrode material lithium nickel cobalt manganese oxide in the battery material layer to the Kuraray activated carbon YP-50F in the capacitor material layer is 1:1;

[0107] (4) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0108] (5) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage battery cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0109] Comparative Example 5 (using the same adhesive on both sides):

[0110] A method for preparing a high-power energy storage battery cell, comprising the following steps:

[0111] (1) Add Kuraray activated carbon YP-50F, conductive agent SP and PVDF binder into solvent NMP at a mass ratio of 90:10:5, stir and disperse evenly to obtain inner layer slurry; add Kuraray activated carbon YP-50F, conductive agent SP and PEDOT:PSS into water at a mass ratio of 55:10:5, stir and disperse evenly to obtain outer layer slurry;

[0112] (2) Aluminum foil was used as the positive electrode current collector. The inner layer slurry was first coated on one side of the aluminum foil, and then the outer layer slurry was coated on the inner layer slurry. After drying at 80°C for 4 hours, a capacitor material layer was obtained on the surface of the positive electrode current collector. The mass ratio of Kuraray activated carbon YP-50F in the inner layer and the outer layer was 3:1, and the total coating amount of Kuraray activated carbon YP-50F was 200g / m 2 ;

[0113] (3) Adding the ternary positive electrode material lithium nickel cobalt manganese oxide, the conductive agent SP and the PVDF binder into water in a mass ratio of 85:10:5, stirring and dispersing them evenly to obtain a battery material layer slurry; coating the battery material layer slurry on the other side of the aluminum foil, drying it at 80°C for 4 hours, and obtaining a battery material layer on the surface of the positive electrode current collector; then rolling and punching to obtain a positive electrode sheet; the mass ratio of the ternary positive electrode material lithium nickel cobalt manganese oxide in the battery material layer to the Kuraray activated carbon YP-50F in the capacitor material layer is 1:1;

[0114] (4) Add hard carbon, conductive agent SP and PVDF binder into solvent NMP in a mass ratio of 85:8:7, stir and disperse evenly to obtain negative electrode slurry; use copper foil as negative electrode current collector, and coat the negative electrode slurry on both sides of the copper foil. The single-side coating amount of hard carbon is 100g / m 2 After drying at 60°C for 2 hours, the negative electrode sheet was obtained by roller pressing and punching;

[0115] (5) The positive electrode sheet, the negative electrode sheet and the PP separator (thickness 30 μm) are assembled into a high-power energy storage battery cell by stacking, and the electrolyte is injected and packaged to obtain a high-power energy storage device.

[0116] The high-power energy storage devices prepared in the above examples and comparative examples were tested for specific capacity at 1C and 50C rates, respectively, and the capacity retention rate at 50C relative to 1C was calculated. The results are shown in Table 1.

[0117] Table 1: Rate performance test results of high power energy storage devices

[0118]

[0119] As can be seen from Table 1, the high-power energy storage devices prepared by the method of the present invention in Examples 1 to 3 have a higher capacity retention rate at a rate of 50C. In Comparative Examples 1 and 2, the battery material and the capacitor material are directly mixed and coated on both sides of the positive electrode current collector. The capacity retention rate at high rate is significantly reduced compared with that in Example 1 and Example 3. This is mainly due to the difference in energy storage mode between the capacitor material and the battery material, which causes the discharge voltage platform of the overall device to be significantly lower than the charging voltage platform, affecting the rate performance. PEDOT:PSS is not added to the capacitor material layer in Comparative Example 3, and the capacity retention rate at 50C is also reduced compared with that in Example 1. This is mainly due to the difference in charge and discharge rates of the battery material and the capacitor material on both sides, which leads to uneven internal current distribution, aggravates the polarization phenomenon, and reduces the overall efficiency. In Comparative Example 4, PEDOT:PSS was added to the battery material layer instead of the capacitor material layer. The capacity retention rate at 50C was improved compared to Comparative Example 3, but still decreased compared to Example 1. This is mainly because the addition of PEDOT:PSS to the battery material layer can only locally improve the conductivity and has limited effect on improving the response speed. In contrast, the addition of PEDOT:PSS to the capacitor material layer can reduce the interface impedance through interface optimization and shorten the delay in charge migration from the capacitor layer to the battery layer. In Comparative Example 5, the same type of binder was used in the battery material layer and the capacitor material layer. Due to the expansion difference between the battery material and the capacitor material on both sides, microcracks were generated at the coating interface, and the local electrode porosity decreased, the local electrolyte infiltration was insufficient, and the lithium ion transmission path was blocked. As a result, during high-rate charge and discharge, the interface resistance surged, causing ohmic polarization, resulting in premature collapse of the voltage platform and a decrease in discharge capacity. Therefore, the capacity retention rate at 50C rate was significantly decreased compared to Example 1.

[0120] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-power energy storage battery cell, characterized in that: It includes a positive electrode sheet and a negative electrode sheet stacked together, and the positive electrode sheet and the negative electrode sheet are separated by a separator; The positive electrode sheet includes a positive electrode current collector and a battery material layer and a capacitor material layer respectively arranged on both sides of the positive electrode current collector; The capacitor material layer includes an inner layer attached to the positive electrode current collector and an outer layer arranged on the inner layer; the components of the inner layer include capacitor material, conductive agent and PVDF binder; the components of the outer layer include capacitor material, conductive agent and PEDOT:PSS; The components of the battery material layer include battery positive electrode material, conductive agent, SBR binder and CMC binder; The negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer arranged on both sides of the negative electrode current collector; the components of the negative electrode material layer include a negative electrode material, a conductive agent and a binder.

2. The high-power energy storage battery cell according to claim 1, characterized in that: In the capacitor material layer, the mass ratio of the capacitor material in the inner layer to that in the outer layer is 2-4:

1.

3. The high-power energy storage battery cell according to claim 1 or 2, characterized in that: In the inner layer of the capacitor material layer, the mass ratio of the capacitor material, the conductive agent and the PVDF binder is 85-95:5-10:5; In the outer layer of the capacitor material layer, the mass ratio of the capacitor material, the conductive agent and PEDOT:PSS is 50-60:5-10:

5.

4. The high-power energy storage battery cell according to claim 1, characterized in that: In the battery material layer, the mass ratio of the battery positive electrode material, the conductive agent, the SBR binder and the CMC binder is 80~90:5~10:2~3:

2.

5. The high-power energy storage battery cell according to claim 1, 2 or 4, characterized in that: The mass ratio of the battery positive electrode material in the battery material layer to the capacitor material in the capacitor material layer is 0.5~2:

1.

6. The high-power energy storage battery cell according to claim 1, characterized in that: In the negative electrode material layer, the mass ratio of the negative electrode material, the conductive agent, and the binder is 80-90:5-10:6-8.

7. The high-power energy storage battery cell according to claim 1, characterized in that: The battery positive electrode material is selected from one or more of lithium battery positive electrode materials and nickel-metal hydride battery positive electrode materials; The capacitor material is selected from one or more of capacitor carbon materials and transition metal oxides; The negative electrode material is selected from one or more lithium-intercalated carbon-based materials.

8. The high-power energy storage battery cell according to claim 1, characterized in that: The binder in the negative electrode material layer is selected from one or more of PVDF, SBR, CMC, and polyacrylic acid.

9. The high-power energy storage battery cell according to claim 1, characterized in that: The conductive agent is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

10. A method for preparing a high-power energy storage battery cell according to any one of claims 1 to 9, characterized in that: The steps include: (1) The components of the inner layer and the outer layer are made into a slurry and coated on one side of the positive electrode current collector in sequence, and dried to obtain a capacitor material layer; (2) The components of the battery material layer are made into a slurry and then coated on the other side of the positive electrode current collector. After drying, the slurry is rolled and punched to obtain a positive electrode sheet; (3) The components of the negative electrode material layer are made into a slurry and then coated on both sides of the negative electrode current collector. After drying, the slurry is rolled and punched to obtain a negative electrode sheet; (4) Assemble the positive electrode sheet, negative electrode sheet and separator into a high-power energy storage cell by stacking them.

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