Hybrid battery capacitor and preparation method and application thereof

Abstract

The invention belongs to the technical field of battery capacitors, and particularly relates to a hybrid battery capacitor and a preparation method and application thereof. The hybrid battery capacitor comprises a shell, a positive pole piece, a diaphragm, a negative pole piece and electrolyte, an active material of the positive pole piece is a ternary material and / or a composite positive pole material of lithium iron phosphate and activated carbon, and the positive pole piece is prepared by coating a layer of the composite positive pole material on a positive current collector and then coating a layer of the activated carbon to form a gradient coating structure; the active material of the negative pole piece is a composite negative pole material of graphite, graphene and activated carbon; the battery cell is formed by assembling a negative pole piece, a diaphragm and a positive pole piece according to a sequence of negative pole-diaphragm-positive pole-diaphragm-negative pole in a lamination or winding manner to form a structure with N layers of positive poles and N + 1 layers of negative poles, the battery cell is packaged in the shell after being subjected to pole lug spot welding, a liquid injection port is reserved, and the battery cell is sealed after being subjected to vacuum liquid injection. And obtaining the hybrid battery capacitor.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery capacitors, and in particular relates to a hybrid battery capacitor and a preparation method and application thereof. Background Art

[0002] Hybrid battery capacitors are electrochemical energy storage devices that combine the advantages of lithium-ion batteries and supercapacitors. By using two different types of electrode materials, the energy density is increased while maintaining a high power density. Hybrid battery capacitors combine the high power density of supercapacitors with the high energy density of lithium-ion batteries. Currently, the energy density of commercial hybrid battery capacitors can reach 100Wh / kg and the power density can reach 10kW / kg, showing great application potential in the field of energy storage. Hybrid battery capacitors usually use activated carbon as the capacitive electrode, while high-capacity battery materials, such as lithium titanate, are used as battery electrodes. For example, the electrode materials of hybrid capacitors usually include high-specific-capacity graphite or lithium titanate as the negative electrode, and highly conductive carbon-based materials such as activated carbon as the positive electrode. By optimizing the nanostructure of the electrode material and the design of the composite material, its energy storage capacity and cycle life can be further improved.

[0003] Currently, hybrid battery capacitors can achieve high energy density while also balancing cycle stability and high power density. They have also demonstrated promising application potential. However, with the acceleration of technological innovation, industrialization, and enhanced cooperation and exchange, a number of technical and cost challenges still need to be overcome to achieve wider application, particularly the performance degradation of hybrid battery capacitors. Unique material and structural designs are urgently needed to achieve a synergistic improvement in energy density and power density. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned deficiencies and provide a hybrid battery capacitor and its preparation method and application.

[0005] In a first aspect, a hybrid battery capacitor adopts the following technical solution:

[0006] A hybrid battery capacitor comprising: a housing, a positive electrode sheet, a diaphragm, a negative electrode sheet and an electrolyte;

[0007] The active material of the positive electrode plate is a ternary material and / or a composite positive electrode material of lithium iron phosphate and activated carbon. The positive electrode plate is formed by first coating a layer of the composite positive electrode material on the positive electrode current collector, and then coating a layer of the activated carbon to form a gradient coating structure to improve the ion transmission performance of the positive electrode surface;

[0008] The active material of the negative electrode plate is a composite negative electrode material of graphite, graphene and activated carbon to enhance the rapid charge and discharge capability of the negative electrode side;

[0009] The battery cell is assembled from a negative electrode sheet, a separator, and a positive electrode sheet in the order of negative electrode-separator-positive electrode-separator-negative electrode by lamination or winding to form a structure with N layers of positive electrode and N+1 layers of negative electrode. The battery cell is packaged in the shell after the electrode tabs are spot-welded, and a liquid injection port is reserved. The shell is sealed after vacuum liquid injection to obtain the hybrid battery capacitor.

[0010] Furthermore, in the composite positive electrode material, the mass fraction of the activated carbon is 9wt% to 50wt%.

[0011] Furthermore, in the composite negative electrode material, the mass fraction of graphene is 2wt% to 4wt%, the mass fraction of activated carbon is 3wt% to 5wt%, and the rest is graphite.

[0012] Furthermore, the capacity ratio of the negative electrode plate to the positive electrode plate is 1.05 to 1.2.

[0013] Furthermore, the electrolyte is a LiPF6 electrolyte with a concentration of 0.8M to 1.2M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:(2 to 2.5).

[0014] Furthermore, the electrolyte further comprises 3 wt% to 8 wt% of fluoroethylene carbonate.

[0015] Furthermore, the electrolyte further comprises 1 wt% to 3 wt% of lithium bis(trifluoromethanesulfonyl)imide.

[0016] Furthermore, the number N of positive electrode layers in the battery core structure is 10 to 20.

[0017] In a second aspect, a method for preparing a hybrid battery capacitor adopts the following technical solution:

[0018] A method for preparing a hybrid battery capacitor comprises the following steps:

[0019] Preparation of positive electrode sheet: The ternary positive electrode material and / or lithium iron phosphate are mixed with activated carbon to form a composite positive electrode material, which is coated on the positive electrode current collector to form a composite material layer, and a layer of activated carbon is further coated on the composite material layer to obtain a positive electrode sheet with a gradient distribution structure;

[0020] Preparation of negative electrode sheet: Graphite, graphene and activated carbon are mixed to form a composite negative electrode material, which is then coated on the negative electrode current collector and dried to form a negative electrode sheet;

[0021] Cell assembly: The positive electrode sheets, negative electrode sheets and separators are stacked or wound in sequence to form a cell structure with N layers of positive electrodes and N+1 layers of negative electrodes. The positive and negative electrodes are staggered to lead out the tabs.

[0022] Pole core packaging: After welding the pole lugs of the battery core, place it into the shell and seal the edges to form a package body, while retaining the liquid injection port;

[0023] Liquid injection and sealing: injecting the electrolyte through the liquid injection port, and sealing the liquid injection port after liquid injection under vacuum conditions to produce the hybrid battery capacitor.

[0024] In a third aspect, an application of a hybrid battery capacitor adopts the following technical solution:

[0025] The hybrid battery capacitor is suitable for power supplies of electric vehicles, energy storage systems of smart grids, power buffer devices of renewable energy, high-frequency pulse power supply equipment, and uninterruptible power supply systems.

[0026] Beneficial effects of the present invention:

[0027] The present invention provides a hybrid battery capacitor that achieves the safety, high energy, and high rate characteristics that are difficult to achieve with traditional lithium-ion batteries and supercapacitors by synergistically optimizing the positive and negative electrode formulas, interface structure, and battery cell levels in the same device. Its positive electrode adopts a composite gradient coating structure of ternary materials and / or lithium iron phosphate and activated carbon. The outer layer is rich in activated carbon with a large specific surface area, and the inner layer is rich in high-capacity crystalline materials. On a microscopic scale, it opens up a dual path of "fast ion diffusion channel + deep lithium storage reservoir", which can significantly reduce interfacial impedance and concentration polarization, improve rate charge and discharge efficiency, and maintain stable electrochemical reactions in the full voltage window of 2.0-4.2V. The negative electrode constructs a three-dimensional conductive network with a ternary composite of graphite-graphene-activated carbon. The high electron mobility of graphene and the transient adsorption characteristics of activated carbon jointly release the polarization increase during high-rate discharge. The SEI film is more complete during the cycle, and the power output and cycle life are simultaneously improved. The battery cell adopts an "N+1" layer negative electrode design, and the N / P capacity ratio is maintained at 1.05~1.2, which not only avoids lithium dendrite deposition but also fully utilizes the positive electrode capacity. Combined with a soft-pack lightweight shell and vacuum liquid injection packaging, it can increase the available energy per unit mass without increasing the weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a physical picture of the battery cell of the hybrid battery capacitor of Example 1.

[0029] Figure 2 This is a scanning electron microscope image of the positive electrode sheet of Example 1.

[0030] Figure 3 This is a scanning electron microscope image of the negative electrode sheet of Example 1.

[0031] Figure 4 This is a graph showing the performance of the hybrid battery capacitor of Example 1 at different rates.

[0032] Figure 5 This is a graph showing the cyclic charge-discharge and capacity retention performance of the hybrid battery capacitor of Example 1. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limiting the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of the present invention have the same meaning as commonly understood by those skilled in the art to which the embodiments of the present invention pertain. The terms used in the embodiments of the present invention are for the purpose of describing the embodiments of the present invention only and are not intended to limit the present invention.

[0035] Those skilled in the art should understand that in the following description of the embodiments of the present invention, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0036] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates otherwise.

[0037] It will be understood by those skilled in the art that the numerical ranges in the embodiments of the present invention are to be understood as also specifically disclosing each intermediate value between the upper and lower limits of the ranges. Each smaller range between any stated value and intermediate value in the stated range, as well as any other stated value or intermediate value in the stated range, is also encompassed by the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0038] Unless otherwise indicated, the technical / scientific terms used herein have the same meanings as commonly understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the embodiments or test examples of the present invention. All documents mentioned in this specification are generally incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this application shall prevail.

[0039] It should be noted that all raw materials and / or reagents in the examples of the present invention are purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0040] Example

[0041] Example 1

[0042] Example 1 provides a hybrid battery capacitor, including an aluminum-plastic shell, a positive electrode plate, a Celgard2500PP separator, a negative electrode plate and an electrolyte; the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of 10:1 of a ternary positive electrode material NCM811 and activated carbon; the positive electrode plate is coated with a layer of the composite positive electrode material on the positive electrode current collector, and then coated with a layer of the activated carbon to form a gradient coating structure; the active material of the negative electrode plate is a composite negative electrode material mixed with 94wt% graphite, 2wt% graphene and 4wt% activated carbon; the N / P value is 1.05; the electrolyte The liquid is a LiPF6 electrolyte with a concentration of 1.0M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:2, and 5wt% of fluoroethylene carbonate and 2wt% of lithium bis(trifluoromethanesulfonyl)imide are further added; the battery core is assembled from a negative electrode plate, a separator, and a positive electrode plate in the order of negative electrode-separator-positive electrode-separator-negative electrode by lamination or winding to form a structure with 20 layers of positive electrode and 21 layers of negative electrode; the battery core is packaged in the shell after the tabs are spot-welded, and a liquid injection port is reserved. The shell is sealed after vacuum liquid injection to obtain a hybrid battery capacitor.

[0043] Example 1 also provides a method for preparing a hybrid battery capacitor, comprising the following steps:

[0044] Preparation of positive electrode sheet: The ternary positive electrode material and / or lithium iron phosphate are mixed with activated carbon to form a composite positive electrode material, which is coated on the positive electrode current collector to form a composite material layer, and a layer of activated carbon is further coated on the composite material layer to obtain a positive electrode sheet with a gradient distribution structure, the scanning electron microscope image of which is shown in FIG. Figure 2 As shown;

[0045] Preparation of negative electrode sheet: Graphite, graphene and activated carbon are mixed to form a composite negative electrode material, which is then coated on the negative electrode current collector and dried to form a negative electrode sheet. The scanning electron microscope image is shown below. Figure 3 As shown;

[0046] Cell assembly: The positive electrode sheet, negative electrode sheet and separator are stacked or wound in sequence to form a cell structure with N layers of positive electrode and N+1 layers of negative electrode. The positive and negative electrodes are staggered to lead out the tabs. The physical structure is as follows Figure 1 As shown;

[0047] Core packaging: After welding the tabs on the battery cell, place it into the shell and seal the edges to form a package while retaining the liquid injection port;

[0048] Liquid injection and sealing: The electrolyte is injected through the liquid injection port, and the liquid injection port is sealed after the liquid is injected under vacuum conditions to produce a hybrid battery capacitor.

[0049] Example 2

[0050] Example 2 provides a hybrid battery capacitor and its preparation method. The differences from Example 1 are that the active material of the positive electrode plate is a composite positive electrode material comprising a ternary positive electrode material, NCM811, and activated carbon in a 4:1 mass ratio; the active material of the negative electrode plate is a composite negative electrode material comprising 93 wt% graphite, 2 wt% graphene, and 5 wt% activated carbon; the N / P ratio is 1.05; the battery cell has 15 positive electrode layers and 16 negative electrode layers; and the electrolyte is a 1.0 M LiPF6 solution, the solvent of which is a mixed solvent of ethylene carbonate and dimethyl carbonate in a 1:2.25 volume ratio, further comprising 5 wt% fluoroethylene carbonate and 2 wt% lithium bis(trifluoromethanesulfonyl)imide.

[0051] Example 3

[0052] Example 3 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material of a ternary positive electrode material NCM811 and activated carbon in a mass ratio of 2:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 94wt% graphite, 3wt% graphene and 3wt% activated carbon; the N / P value is 1.10; the number of positive electrode layers of the battery cell is 12 layers, and the number of negative electrode layers is 13 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.0M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:2.20, and 3wt% of fluoroethylene carbonate and 1wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0053] Example 4

[0054] Example 4 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material of a ternary positive electrode material NCM811 and activated carbon in a mass ratio of 1:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 91wt% graphite, 4wt% graphene and 5wt% activated carbon; the N / P value is 1.10; the number of positive electrode layers of the battery cell is 10 layers, and the number of negative electrode layers is 11 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.2M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:2.50, and 8wt% of fluoroethylene carbonate and 3wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0055] Example 5

[0056] Example 5 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material of a ternary positive electrode material NCM622 and activated carbon with a mass ratio of 9:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 94wt% graphite, 2wt% graphene and 4wt% activated carbon; the N / P value is 1.05; the number of positive electrode layers of the battery cell is 20 layers, and the number of negative electrode layers is 21 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 0.9M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.20, and 5wt% of fluoroethylene carbonate and 2wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0057] Example 6

[0058] Example 6 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material of a ternary positive electrode material NCM523 and activated carbon in a mass ratio of 5:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 95wt% graphite, 2wt% graphene and 3wt% activated carbon; the N / P value is 1.10; the number of positive electrode layers of the battery cell is 14 layers, and the number of negative electrode layers is 15 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.0M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:2.00, and 6wt% of fluoroethylene carbonate and 2wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0059] Example 7

[0060] Example 7 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material of a ternary positive electrode material NCA111 and activated carbon with a mass ratio of 9:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 93wt% graphite, 2wt% graphene and 5wt% activated carbon; the N / P value is 1.20; the number of positive electrode layers of the battery cell is 18 layers, and the number of negative electrode layers is 19 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.2M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.30, and 8wt% of fluoroethylene carbonate and 3wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0061] Example 8

[0062] Example 8 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of LFP and activated carbon of 9:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 93wt% graphite, 3wt% graphene and 4wt% activated carbon; the N / P value is 1.05; the number of positive electrode layers of the battery cell is 14 layers, and the number of negative electrode layers is 15 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 0.8M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.25, and 4wt% of fluoroethylene carbonate and 1wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0063] Example 9

[0064] Example 9 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of NCM811, LFP and activated carbon of 4:4:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 94wt% graphite, 2wt% graphene and 4wt% activated carbon; the N / P value is 1.10; the number of positive electrode layers of the battery cell is 16 layers, and the number of negative electrode layers is 17 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.0M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.00, and 5wt% of fluoroethylene carbonate and 2wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0065] Example 10

[0066] Example 10 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of NCM811 and activated carbon of 10:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 92wt% graphite, 4wt% graphene and 4wt% activated carbon; the N / P value is 1.05; the number of positive electrode layers of the battery cell is 12 layers, and the number of negative electrode layers is 13 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.2M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.50, and 7wt% of fluoroethylene carbonate and 3wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0067] Example 11

[0068] Example 11 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of NCM811 and activated carbon of 3:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 94wt% graphite, 2wt% graphene and 4wt% activated carbon; the N / P value is 1.20; the number of positive electrode layers of the battery cell is 11 layers, and the number of negative electrode layers is 12 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 1.1M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.10, and 3wt% of fluoroethylene carbonate and 2wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0069] Example 12

[0070] Example 12 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of NCM811 and activated carbon of 1.2:1; the active material of the negative electrode plate is a composite negative electrode material mixed with 90wt% graphite, 4wt% graphene and 5wt% activated carbon; the N / P value is 1.10; the number of positive electrode layers of the battery cell is 13 layers, and the number of negative electrode layers is 14 layers; the electrolyte is a LiPF6 electrolyte with a concentration of 0.8M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:2.40, and 6wt% of fluoroethylene carbonate and 1wt% of lithium bis(trifluoromethanesulfonyl)imide are also added.

[0071] Comparative Example

[0072] Comparative Example 1

[0073] Comparative Example 1 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the surface of the composite positive electrode material is not coated with an activated carbon layer, that is, the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of 10:1 between the ternary positive electrode material NCM811 and activated carbon; the positive electrode plate adopts a layer of composite positive electrode material coated on the positive electrode current collector.

[0074] Comparative Example 2

[0075] Comparative Example 2 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that the positive electrode plate is not coated with a composite positive electrode material, that is, the positive electrode plate is coated with a layer of activated carbon with the same thickness as Example 1 on the positive electrode collector.

[0076] Comparative Example 3

[0077] Comparative Example 3 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of ternary positive electrode material NCM811 and activated carbon of 95:5.

[0078] Comparative Example 4

[0079] Comparative Example 4 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the active material of the positive electrode plate is a composite positive electrode material with a mass ratio of ternary positive electrode material NCM811 and activated carbon of 2:3.

[0080] Comparative Example 5

[0081] Comparative Example 5 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the active material of the negative electrode plate is graphite.

[0082] Comparative Example 6

[0083] Comparative Example 6 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the active material of the negative electrode plate is a composite negative electrode material mixed with 94 wt% graphite and 6 wt% graphene.

[0084] Comparative Example 7

[0085] Comparative Example 7 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the active material of the negative electrode plate is a composite negative electrode material mixed with 94 wt% graphite and 6 wt% activated carbon.

[0086] Comparative Example 8

[0087] Comparative Example 8 provides a hybrid battery capacitor and its preparation method. The difference from Example 1 is that an equal amount of fluoroethylene carbonate is replaced by lithium bis(trifluoromethanesulfonyl)imide, that is, 7wt% of lithium bis(trifluoromethanesulfonyl)imide is also added to the electrolyte.

[0088] Comparative Example 9

[0089] Comparative Example 9 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that an equal amount of lithium bis(trifluoromethanesulfonyl)imide is replaced by fluoroethylene carbonate, that is, 7 wt % of fluoroethylene carbonate is also added to the electrolyte.

[0090] Comparative Example 10

[0091] Comparative Example 10 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the number of positive electrode layers of the battery cell is 8, and the number of negative electrode layers is 9.

[0092] Comparative Example 11

[0093] Comparative Example 11 provides a hybrid battery capacitor and a preparation method thereof. The difference from Example 1 is that the number of positive electrode layers of the battery cell is 22, and the number of negative electrode layers is 23.

[0094] Application Examples

[0095] The hybrid battery capacitors provided in Examples 1 to 12 are applied to power supplies for electric vehicles, energy storage systems for smart grids, power buffer devices for renewable energy, high-frequency pulse power supply equipment, and uninterruptible power supply systems.

[0096] Performance Testing

[0097] The performance of the hybrid battery capacitor prepared in Example 1 was tested as follows:

[0098] Electrochemical tests were conducted on a Xinwei charge-discharge instrument. Activation was performed using a constant current constant voltage (CCCV 0.1C-0.01C, 5mV) method with a voltage range of 2.0-4.2V. Rate performance was tested at current densities of 1C / 5C / 10C / 20C with a voltage range of 2.0-4.2V. Cycling performance was tested at a current density of 1C with a voltage range of 2.0-4.2V and a constant voltage time of 1 minute. The performance of the hybrid battery capacitor prepared in Example 1 at different rates is detailed in the table below. Figure 4 ; For details on the performance of cycle charge and discharge and capacity retention, please see Figure 5 .

[0099] Should Figure 4The capacity and coulombic efficiency of the hybrid battery capacitor of Example 1 at different charge and discharge rates (1C, 5C, 10C, 20C, and back to 1C) as a function of the number of cycles are shown. The battery capacitor exhibits good rate performance. Although the discharge capacity decreases as the rate increases from 1C to 20C, a considerable amount of capacity can still be maintained at a high rate of 20C. The gradient coating of the positive electrode (composite material layer + pure activated carbon layer) facilitates rapid ion transport at the electrode / electrolyte interface, reducing polarization under high current. The composite negative electrode (graphite / graphene / activated carbon) provides a highly conductive network and a high specific surface area, supporting rapid lithium ion insertion and extraction. When the rate is restored to 1C, the capacity is almost restored to the initial level, showing good structural stability and reversibility. The coulombic efficiency remains high (close to 100%) at all rates, indicating that there are few side reactions.

[0100] Figure 5 The long-term stability of the battery capacitor of Example 1 is shown over 500 cycles at a 1C rate, with the charge and discharge capacity and coulombic efficiency plotted. After 500 cycles, the capacity retention is high, with only slow decay. Throughout the cycling test, the coulombic efficiency is very close to 100%. The stable electrode materials, optimized N / P ratio, electrolyte additives, and overall structural integrity all contribute to its long cycle life.

[0101] The internal resistance, electrostatic capacitance, and specific capacitance performance of the hybrid battery capacitors prepared in Examples 1 to 12 and Comparative Examples 1 to 11 were tested under the same conditions, as follows:

[0102] Internal resistance

[0103] The hybrid battery capacitors provided in Examples 1 to 12 and Comparative Examples 1 to 11 are charged to a rated voltage U using a constant current I. R , record this moment as t0, and discharge the sample with a constant current I to the minimum working voltage U min , record the voltage U at t0+30ms i . Test 3 times and take the average value. According to the formula R=(U R -U i ) / 2I to calculate the internal resistance.

[0104] electrostatic capacitance

[0105] The hybrid battery capacitors provided in Examples 1 to 12 and Comparative Examples 1 to 11 are charged to a rated voltage U using a constant current. R , and then discharge the sample at a constant current to the minimum working voltage U min , a total of 5 cycles, record the discharge time t from 80% of the rated voltage to the minimum working voltage, according to the formula C=I·t / (0.8U R -Umin ) Calculate the electrostatic capacitance of each cycle and take the average value.

[0106] Specific capacity

[0107] The hybrid battery capacitors provided in Examples 1 to 12 and Comparative Examples 1 to 11 are charged to a rated voltage U using a constant current I. R , then keep constant pressure for 30 minutes, let it stand for 5 seconds, and discharge the sample with a constant current I to the minimum working voltage U min , record the voltage U and time t, repeat three times and take the average value. Calculate the stored energy and specific energy according to the formula W = ∫IUdt / 3600 and E = W / M.

[0108] The internal resistance, electrostatic capacitance and specific capacitance performance test results of the hybrid battery capacitors prepared in Examples 1 to 12 and Comparative Examples 1 to 11 were respectively tested under the same conditions and are shown in Table 1 below.

[0109] Table 1 Hybrid battery capacitor internal resistance, electrostatic capacity, specific capacity performance test

[0110]

[0111]

[0112] The data in Table 1 systematically compares the performance of Examples 1 to 12 with Comparative Examples 1 to 11 in terms of internal resistance, electrostatic capacitance and specific capacity (energy storage). The hybrid battery capacitors provided by Examples 1-12 generally exhibit good overall performance. The internal resistance is controlled at a relatively low level (0.52mΩ to 0.75mΩ), indicating that the device has low internal loss and good power characteristics potential. In terms of electrostatic capacitance, the measured values ​​of Examples 1 to 12 (ranging from approximately 4320F to 9451F) are highly consistent with their nominal capacities, with most reaching more than 96% of the nominal values, or even close to 100%, demonstrating excellent charge storage capacity and design achievement. More critical is the specific energy (Wh / kg). Examples 1 to 12 generally reach a high level of 106Wh / kg to 133Wh / kg, while the nominal energy compliance is mostly above 92%, and some exceed 100%, which fully demonstrates the advantages of the design of the present invention in energy density, successfully combining the high energy of the battery with some of the characteristics of the capacitor.

[0113] Comparative Example 1 does not coat the surface of the composite positive electrode material with an activated carbon layer. Its internal resistance is slightly higher, and its nominal capacity and energy compliance are lower than those of Example 1, demonstrating the positive effect of the positive electrode gradient coating structure on improving overall performance. Comparative Example 2 uses only activated carbon for the positive electrode. Although the internal resistance may be lower, its stored energy and specific energy (only 46Wh / kg) are far lower than those of the examples, emphasizing the necessity of battery-type materials (such as NCM and LFP) in the composite positive electrode material to achieve high energy density.

[0114] Comparative Examples 3 and 4 changed the ratio of the positive electrode active material to the activated carbon. In particular, when the ratio of activated carbon in Comparative Example 4 was too high, the energy density decreased significantly (95.85Wh / kg), indicating that the ratio range proposed in the present invention (such as 10:1 in Example 1, 2:1 in Example 3, etc.) is important for performance optimization.

[0115] Comparative Examples 5, 6, and 7 respectively tested negative electrodes using only graphite, lacking graphene, or lacking activated carbon. The results showed that their internal resistance was higher or their specific energy and electrostatic capacity performance were inferior to those of the embodiment using a composite negative electrode of graphite, graphene, and activated carbon (such as Example 1), confirming the criticality of the composite negative electrode structure and its components (especially graphene and activated carbon) in improving the conductive network, buffering high-rate polarization, and improving overall performance.

[0116] Comparative Examples 8 and 9 adjusted the electrolyte additives, and the results were different from those of the examples, revealing that the specific electrolyte additives selected by the present invention (such as the combination and proportion of fluoroethylene carbonate and lithium bis(trifluoromethanesulfonyl)imide) help achieve better performance.

[0117] Comparative Examples 10 and 11 used cell layers exceeding the preferred range of the present invention (N=10-20), and their performance, especially the specific energy, was not as good as that of the embodiments within the optimal range, indicating that appropriate cell layer design is also one of the factors for achieving optimal performance.

[0118] In summary, the data in Table 1 strongly demonstrate the effectiveness of the hybrid battery capacitor design proposed in this invention. By adopting a specific positive electrode gradient coating structure, a positive and negative electrode composite material system (including ternary / LFP, activated carbon, graphite, graphene, etc.) and its optimized component ratio, a specific electrolyte formulation, and a suitable battery cell structure (such as N-layer positive electrode, N+1 layer negative electrode, N in the range of 10-20), a hybrid battery capacitor with low internal resistance, high electrostatic capacitance, and high specific energy can be successfully prepared. Compared with designs lacking key technical features, the performance is significantly improved.

[0119] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A hybrid battery capacitor, characterized in that: include: Shell, positive electrode sheet, diaphragm, negative electrode sheet and electrolyte; The active material of the positive electrode plate is a ternary material and / or a composite positive electrode material of lithium iron phosphate and activated carbon. The positive electrode plate is formed by first coating a layer of the composite positive electrode material on the positive electrode current collector, and then coating a layer of the activated carbon to form a gradient coating structure to improve the ion transmission performance of the positive electrode surface; The active material of the negative electrode plate is a composite negative electrode material of graphite, graphene and activated carbon to enhance the rapid charge and discharge capability of the negative electrode side; The battery cell is assembled from a negative electrode sheet, a separator, and a positive electrode sheet in the order of negative electrode-separator-positive electrode-separator-negative electrode by lamination or winding to form a structure with N layers of positive electrode and N+1 layers of negative electrode. The battery cell is packaged in the shell after the electrode tabs are spot-welded, and a liquid injection port is reserved. The shell is sealed after vacuum liquid injection to obtain the hybrid battery capacitor.

2. The hybrid battery capacitor according to claim 1, wherein: In the composite positive electrode material, the mass fraction of the activated carbon is 9 wt% to 50 wt%.

3. The hybrid battery capacitor according to claim 1, wherein: In the composite negative electrode material, the mass fraction of graphene is 2wt% to 4wt%, the mass fraction of activated carbon is 3wt% to 5wt%, and the rest is graphite.

4. The hybrid battery capacitor according to claim 1, wherein: The capacity ratio of the negative electrode plate to the positive electrode plate is 1.05 to 1.

2.

5. The hybrid battery capacitor according to claim 1, wherein: The electrolyte is a LiPF6 electrolyte with a concentration of 0.8M to 1.2M, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1: (2 to 2.5).

6. The hybrid battery capacitor according to claim 5, characterized in that The electrolyte also includes 3wt% to 8wt% of fluoroethylene carbonate.

7. The hybrid battery capacitor according to claim 6, wherein: The electrolyte also includes 1 wt% to 3 wt% of lithium bis(trifluoromethanesulfonyl)imide.

8. The hybrid battery capacitor according to any one of claims 1 to 7, characterized in that: The number N of positive electrode layers in the battery core structure is 10 to 20.

9. A method for preparing a hybrid battery capacitor according to claim 8, characterized in that: The steps include: Preparation of positive electrode sheet: The ternary positive electrode material and / or lithium iron phosphate are mixed with activated carbon to form a composite positive electrode material, which is coated on the positive electrode current collector to form a composite material layer, and a layer of activated carbon is further coated on the composite material layer to obtain a positive electrode sheet with a gradient distribution structure; Preparation of negative electrode sheet: Graphite, graphene and activated carbon are mixed to form a composite negative electrode material, which is then coated on the negative electrode current collector and dried to form a negative electrode sheet; Cell assembly: The positive electrode sheets, negative electrode sheets and separators are stacked or wound in sequence to form a cell structure with N layers of positive electrodes and N+1 layers of negative electrodes. The positive and negative electrodes are staggered to lead out the tabs. Pole core packaging: After welding the pole lugs of the battery core, place it into the shell and seal the edges to form a package body, while retaining the liquid injection port; Liquid injection and sealing: injecting the electrolyte through the liquid injection port, and sealing the liquid injection port after liquid injection under vacuum conditions to produce the hybrid battery capacitor.

10. An application of the hybrid battery capacitor according to claim 8, characterized in that: The hybrid battery capacitor is suitable for power supplies of electric vehicles, energy storage systems of smart grids, power buffer devices of renewable energy, high-frequency pulse power supply equipment, and uninterruptible power supply systems.

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