Secondary battery, its preparation method, lithium supplementation method, and energy storage device

Abstract

The present invention provides a secondary battery, a preparation method and a lithium supplementation method thereof, and an energy storage device. The preparation method includes: embedding a first cathode material into pores of a hydrogen bond organic framework material having an interpenetrating structure to obtain a composite encapsulation material; sequentially mixing, homogenizing and coating raw materials including the composite encapsulation material and a second cathode material to obtain a composite cathode plate; under the action of ultrasonic waves, the hydrogen bond organic framework material in the composite cathode plate can dissociate and release the first cathode material to supplement lithium for the secondary battery; assembling a component including the composite cathode plate, a negative electrode plate and a separator to obtain a secondary battery; wherein the first cathode material is any one or more of lithium nickel cobalt manganate material, lithium cobaltate material and lithium nickel cobalt manganese aluminate material. The above secondary battery dissociates the hydrogen bond organic framework material in the composite cathode plate under the action of ultrasonic waves, and slowly releases the encapsulated lithium source material, thereby realizing effective lithium supplementation.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and more particularly, to a secondary battery, a preparation method and a lithium supplementation method thereof, and an energy storage device. Background Art

[0002] Due to advantages such as high energy density and long cycle life, secondary batteries have been widely used. However, lithium loss inevitably occurs during the cycling of secondary batteries, mainly attributed to electrolyte decomposition, the formation of the SEI (solid electrolyte interface) film, and the instability of lithium metal anodes. These processes not only lead to the attenuation of battery capacity but also cause irreversible chemical changes, reducing the cycle life and safety of the battery. Therefore, lithium supplementation technology is usually adopted for lithium supplementation.

[0003] However, current lithium supplementation technologies (such as prelithiation and cathode lithium supplementation agents) have problems such as complex processes, high costs, and the risk of local lithium precipitation caused by the one-time release of lithium sources. Among them, prelithiation technology requires the additional embedding of lithium sources or lithium metal foils during battery manufacturing, and then through specific processes, lithium is released from the lithium source and supplemented into the battery. This process not only increases the difficulty of battery manufacturing but also may introduce new instability factors, such as the uneven distribution of lithium metal foils inside the battery, affecting the performance and safety of the battery. For prelithiation technology using lithium metal as the lithium supplementation source, due to the high price of lithium metal itself and the strict anhydrous and anaerobic environment required during manufacturing and storage, the production cost is greatly increased. In addition, some lithium supplementation technologies require the use of expensive equipment and special additives, further driving up the cost.

[0004] In addition, the one-time release of lithium sources is a common problem in existing lithium supplementation technologies. Although the addition of conventional lithium sources can reduce the initial attenuation during the formation stage of the battery, the capacity will continue to decline during the battery cycling process and cannot be supplemented again. At the same time, the one-time release of lithium sources will cause the lithium ion concentration to be too high in local areas, thus forming lithium dendrites inside the battery. Lithium dendrites not only pierce the separator, causing internal short circuits in the battery, but may also continuously grow during the charge and discharge process of the battery, ultimately affecting the cycle life and safety of the battery. In addition, due to the extremely high activity of lithium, the growth of lithium dendrites may also trigger thermal runaway inside the battery, causing serious safety risks. Therefore, the lithium supplementation technology still lacks a dynamic compensation mechanism for on-demand and controllable release of active lithium during battery service, and it is difficult to achieve real-time matching of lithium loss and replenishment. Summary of the Invention

[0005] The main object of the present invention is to provide a secondary battery, a preparation method and a lithium supplementation method thereof, and an energy storage device to solve the problems of complex processes, high costs, and the risk of local lithium precipitation caused by the one-time release of lithium sources in existing lithium supplementation technologies.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a secondary battery, the preparation method comprising: Step S1, embedding a first cathode material into the pores of a hydrogen-bonded organic framework material having an interpenetrating structure to obtain a composite encapsulation material; Step S2, successively mixing, homogenizing and coating raw materials including the composite encapsulation material and a second cathode material to obtain a composite cathode electrode sheet; under the action of ultrasonic waves, the hydrogen-bonded organic framework material in the composite cathode electrode sheet can dissociate and release the first cathode material to replenish lithium for the secondary battery; and Step S3, assembling a component including the composite cathode electrode sheet, the anode electrode sheet and the separator to obtain a secondary battery; wherein the first cathode material is any one or more of lithium nickel cobalt manganese oxide material, lithium cobalt oxide material and lithium nickel cobalt manganese aluminum oxide material.

[0007] Further, in the above step S1, the hydrogen-bonded organic framework material is selected from any one or more of HOF-TATB, HOF-BTB, HOF-101, HOF-102 and ZJU-HOF-10; and / or, the composite encapsulation material is obtained by mixing and reacting a second raw material including a first raw material corresponding to the hydrogen-bonded organic framework material, the first cathode material and a solvent; wherein the first raw material is selected from any one of 1,3,5-triamino-2,4,6-trinitrobenzene, 1,3,5-tris(4-carboxyphenyl)benzene, 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene, 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4'6,6'-hexamethyl-2,2'-biphenyl.

[0008] Further, in the above step S1, the mass ratio of the first cathode material to the hydrogen-bonded organic framework material is 1-5:1.

[0009] Further, in the above step S2, the mass ratio of the composite encapsulation material to the second cathode material is 5-20:80-95; and / or, the second cathode material is any one or more of lithium nickel cobalt manganese oxide material, lithium iron phosphate material and lithium cobalt oxide material.

[0010] Further, in the above step S2, the rotation speed of the mixing is 50-200 rpm, and / or, the mixing time is 5-30 min.

[0011] According to another aspect of the present invention, there is provided a secondary battery, including a cathode electrode sheet, an anode electrode sheet and a separator, the secondary battery is prepared by the above method for preparing a secondary battery; wherein, the cathode electrode sheet includes a composite encapsulation material and a second cathode material; the composite encapsulation material includes a first cathode material and a hydrogen-bonded organic framework material having an interpenetrating structure; the first cathode material is embedded in the pores of the hydrogen-bonded organic framework material.

[0012] According to another aspect of the present invention, an energy storage device is provided. The energy storage device includes a battery pack, the battery pack includes one or more battery modules, each battery module independently includes one or more secondary batteries, and each secondary battery independently includes a positive electrode terminal, a positive electrode plate, and a positive electrode connecting piece. The positive electrode terminal is disposed on the top cover of the secondary battery, the positive electrode terminal is connected to the positive electrode connecting piece, and the positive electrode connecting piece is connected to the positive electrode tab on the positive electrode plate; the secondary battery is the above-mentioned secondary battery; a ultrasonic generator is matched with the secondary battery.

[0013] Further, the ultrasonic generator is disposed inside the secondary battery, and the ultrasonic generator is connected to the positive electrode connecting piece.

[0014] Further, the ultrasonic generator is disposed outside the secondary battery, and the ultrasonic generator is directly or indirectly connected to the positive electrode terminal; wherein, the ultrasonic generator is disposed inside the battery module, or the ultrasonic generator is disposed outside the battery module and inside the battery pack, or the ultrasonic generator is disposed outside the battery pack.

[0015] According to another aspect of the present invention, a method for lithium supplementation of the above-mentioned secondary battery is provided. The secondary battery includes a positive electrode terminal, a positive electrode plate, and a positive electrode connecting piece. The positive electrode terminal is disposed on the top cover of the secondary battery, the positive electrode terminal is connected to the positive electrode connecting piece, and the positive electrode connecting piece is connected to the positive electrode tab on the positive electrode plate; the method for lithium supplementation includes: matching a ultrasonic generator inside or outside the secondary battery, and using the ultrasonic generator to perform ultrasonic treatment on the positive electrode terminal or the positive electrode tab of the secondary battery, so that the hydrogen bond organic framework material in the composite positive electrode plate is dissociated and the first positive electrode material is released, thereby realizing lithium supplementation of the secondary battery.

[0016] Further, the battery management system is electrically connected to the secondary battery and the ultrasonic generator respectively, and the battery management system is used to detect the degree of cell attenuation of the secondary battery, and set the frequency, power, and action time of the ultrasonic generator.

[0017] Further, the ultrasonic generator is started when the capacity of the secondary battery decays to a certain capacity value, wherein the capacity value is any value within the range of 80% to 90% of the initial capacity value of the secondary battery.

[0018] Further, when an ultrasonic generator is externally matched to the secondary battery, the ultrasonic generator is directly or indirectly connected to the positive electrode terminal. The ultrasonic generator is used to perform ultrasonic treatment on the positive electrode terminal of the secondary battery. The frequency of the ultrasonic generator is 1 - 2 MHz, the power of the ultrasonic generator is 5 - 15 MPa, and / or the action time of the ultrasonic generator is 60 - 120 s; and / or when an ultrasonic generator is internally matched to the secondary battery, the ultrasonic generator is connected to the positive electrode connecting piece, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode tab of the secondary battery. The frequency of the ultrasonic generator is 0.01 - 2 MHz, the power of the ultrasonic generator is 0.01 - 7.5 MPa, and / or the action time of the ultrasonic generator is 10 - 120 s.

[0019] Applying the technical solution of the present invention, the beneficial effects of the present application are as follows: By doping a composite encapsulation material in the composite positive electrode sheet, and embedding the high-capacity first positive electrode material (lithium source material) in the pores of the hydrogen-bonded organic framework material (HOF material) with an interpenetrating structure in the composite encapsulation material, under the action of ultrasonic waves, the hydrogen-bonded organic framework material can be dissociated, and the encapsulated lithium source material can be slowly released, so as to supplement lithium during the service period of the secondary battery, effectively avoiding the risk of local lithium precipitation caused by the one-time release of the lithium supplement material. Compared with metal-organic framework materials (MOF materials) and covalent organic framework materials (COF materials), the intermolecular force of HOF materials is weaker, which is more conducive to its dissociation. And the high-capacity first positive electrode material is encapsulated in the framework and can be effectively protected. Preferably, the type of the first positive electrode material is within the above range, which can better slowly release lithium ions. The preparation method of the present application is simple and has a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The schematic diagrams in the specification drawings forming a part of the present application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0021] Figure 1 It shows a schematic flow chart of the preparation method of the secondary battery - the lithium supplement method of the secondary battery in Embodiment 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0023] As analyzed in the background art of the present application, in the prior art, the lithium supplement technology has problems such as complex process, high cost, and the risk of local lithium precipitation caused by the one-time release of the lithium source. To solve the above problems, the present application provides a secondary battery, a preparation method thereof, and a lithium supplement method.

[0024] In a typical embodiment of the present application, a method for preparing a secondary battery is provided. The preparation method includes: Step S1, embedding a first cathode material into the pores of a hydrogen-bonded organic framework material having an interpenetrating structure to obtain a composite encapsulation material; Step S2, successively mixing, homogenizing, and coating raw materials including the composite encapsulation material and a second cathode material to obtain a composite cathode electrode sheet; under the action of ultrasonic waves, the hydrogen-bonded organic framework material in the composite cathode electrode sheet can dissociate and release the first cathode material to perform lithium supplementation for the secondary battery; and Step S3, assembling components including the composite cathode electrode sheet, a negative electrode sheet, and a separator to obtain a secondary battery; wherein the first cathode material is any one or more of lithium nickel cobalt manganate material, lithium cobaltate material, and lithium nickel cobalt aluminum manganate material.

[0025] In the present application, by doping a composite encapsulation material in the composite cathode electrode sheet, and the high-capacity first cathode material (lithium source material) in the composite encapsulation material is embedded in the pores of a hydrogen-bonded organic framework material (HOF material) having an interpenetrating structure. Under the action of ultrasonic waves, the hydrogen-bonded organic framework material can be dissociated, and the encapsulated lithium source material can be slowly released, so as to perform lithium supplementation during the service period of the secondary battery, effectively avoiding the risk of local lithium precipitation caused by the one-time release of the lithium supplementation material. Compared with metal-organic framework materials (MOF materials) and covalent organic framework materials (COF materials), the intermolecular force of HOF materials is weaker, which is more conducive to its dissociation. And the high-capacity first cathode material is encapsulated in the framework and can be effectively protected. Preferably, the type of the first cathode material is within the above range, which can better slowly release lithium ions. The preparation method of the present application is simple and has a low cost.

[0026] Wherein, the interpenetrating structure of the HOF material means that in the crystal structure of the HOF material, two or more independent three-dimensional frameworks are interpenetrated with each other through non-covalent interactions (such as hydrogen bonds, π-π stacking, or van der Waals forces) to form an intertwined network in space. And the interpenetrating structure can preferably maintain the porous characteristics and can adapt to different molecular shapes and sizes when adsorbing molecules.

[0027] In one embodiment of the present application, in the above step S1, the hydrogen-bonded organic framework material is selected from any one or more of HOF-TATB, HOF-BTB, HOF-101, HOF-102, and ZJU-HOF-10; and / or, the composite encapsulation material is obtained by mixing and reacting a second raw material including the corresponding first raw material of the hydrogen-bonded organic framework material, the first cathode material, and a solvent; wherein, the first raw material is selected from any one of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB), 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene (H4TBAPy), 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4',6,6'-hexamethyl-2,2'-biphenyl (H4TCHB).

[0028] Preferably, the preparation method of the composite encapsulation material is as follows:

[0029] Preparation of the first cathode @ HOF-TATBDE: Synthesized by the diffusion method. Dissolve 50 mg of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and the first cathode material in 10 mL of the solvent dimethylformamide solution (DMF) as the bottom layer solution. The middle layer solution is a mixed solution of methanol and water (the volume ratio of the two is 1:1). The upper layer is n-hexane. Then, after standing at room temperature for 48 h, collect the sample at the interface, wash it 3 times with methanol to remove the residual solvent, and vacuum dry it at 60 °C for 12 h to obtain the composite encapsulation material.

[0030] Preparation of the first cathode @ HOF-BTB: Add 80 mg of 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) and the first cathode material to 3 mL of the solvent methanol, then transfer it to a 20 mL autoclave, heat it to 90 °C and react for 5 h, take it out of the oven and let it stand for 1 - 2 days. Wash it 3 times with methanol to remove the residual solvent, and vacuum dry it at 60 °C for 12 h to obtain the composite encapsulation material.

[0031] Preparation of the first cathode @ HOF-101: Dissolve 150 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene H4TBAPy (0.225 mmol) and the first cathode material in 22.5 mL of DMF solution, add 90 mL of methanol to it and stir for 2 min to obtain a mixture. Let the mixture stand at room temperature for 12 h, collect the product by centrifugation, wash it three times with ethanol, and vacuum dry it at 60 °C for 12 h to obtain the composite encapsulation material.

[0032] Preparation of the first positive electrode @HOF-102: Dissolve 200 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene H4TNAPy (0.225 mmol) and the first positive electrode material in 60 mL of DMF solution to obtain a clear yellow solution. Subsequently, pour the solution into 160 mL of acetone and stir to obtain a suspension. Stir the suspension continuously for 12 h, collect the product by centrifugation, wash it 4 times with acetone, and dry it under vacuum at 60 °C to obtain the composite encapsulation material.

[0033] Preparation of the first positive electrode @ZJU-HOF-10: Add 20 mg of 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4',6,6'-hexamethyl-2,2'-biphenyl H4TCHB, the first positive electrode material, and 8 mL of tetrahydrofuran solution (THF) into a 20 mL vial. After ultrasonic dissolution, seal it with plastic wrap. After puncturing 5 pores with a needle, place the vial in a sealed jar (with a specification of 250 mL) containing 50 mL of dichloromethane and seal it. After placing it at room temperature for one week, the composite encapsulation material is obtained at the bottom of the vial.

[0034] In an embodiment of the present application, in the above step S1, the mass ratio of the first positive electrode material to the hydrogen-bonded organic framework material is 1-5:1.

[0035] Preferably, the mass ratio of the first positive electrode material to the hydrogen-bonded organic framework material is within the above range, which not only helps the high-capacity first positive electrode material to be fully and evenly embedded in the pores of the HOF material, reducing the decrease in reactivity caused by material waste or over-encapsulation, but also helps to better match the release of lithium source material by dissociating the HOF material with the lithium loss of the battery during battery service, so as to achieve a better lithium compensation effect. At the same time, the stability of the HOF material helps to better protect the first positive electrode material during battery cycling and reduce the inactive consumption of lithium ions.

[0036] In an embodiment of the present application, in the above step S2, the mass ratio of the composite encapsulation material to the second positive electrode material is 5-20:80-95; and / or, the second positive electrode material is any one or more of lithium nickel cobalt manganese oxide material, lithium iron phosphate material, and lithium cobalt oxide material.

[0037] Preferably, the mass ratio of the composite encapsulation material to the second positive electrode material and the type of the second positive electrode material are within the above range, which helps to improve the overall energy density of the battery. During battery service, the slow release of the first positive electrode material in the composite encapsulation material helps to further compensate for lithium loss. At the same time, the second positive electrode material maintains its original characteristics and jointly improves the cycle stability of the battery with the composite encapsulation material.

[0038] In an embodiment of the present application, in the above step S2, the rotation speed of mixing is 50-200 rpm, and / or the mixing time is 5-30 min.

[0039] Preferably, the rotation speed and time of mixing are within the above ranges, which helps the composite encapsulation material and the second cathode material to be fully mixed, thus facilitating more uniform subsequent coating.

[0040] In order to better match the composite cathode electrode sheet, preferably in the above step S3, the negative electrode sheet is a graphite negative electrode sheet and / or a silicon-based negative electrode sheet; and / or the separator is selected from any one or more of polyethylene, polypropylene, and ceramic-coated separators. The positive current collector can be various materials suitable for being used as the positive current collector of a lithium-ion battery. For example, the positive current collector can include, but is not limited to, metal foils, etc., and more specifically can include, but is not limited to, aluminum foils, etc.

[0041] In another typical embodiment of the present application, a secondary battery is provided, which includes a positive electrode sheet, a negative electrode sheet, and a separator. The secondary battery is prepared by the above-mentioned preparation method of the secondary battery; wherein, the positive electrode sheet includes a composite encapsulation material and a second cathode material; the composite encapsulation material includes a first cathode material and a hydrogen-bonded organic framework material with an interpenetrating structure; the first cathode material is embedded in the pores of the hydrogen-bonded organic framework material.

[0042] The secondary battery obtained by the above-mentioned preparation method of the secondary battery has a high energy density. The HOF material in the positive electrode sheet can dissociate and release the high-capacity first cathode material, which can better replenish lithium according to lithium loss, avoiding the reduction of energy density and the risk of local lithium precipitation caused by the one-time release of lithium sources, thus significantly improving the cycle life of the battery.

[0043] In still another typical embodiment of the present application, an energy storage device is provided. The energy storage device includes a battery pack. The battery pack includes one or more battery modules. Each battery module independently includes one or more secondary batteries. Each secondary battery independently includes a positive electrode terminal, a positive electrode sheet, and a positive connection piece. The positive electrode terminal is arranged on the top cover of the secondary battery. The positive electrode terminal is connected to the positive connection piece, and the positive connection piece is connected to the positive electrode tab on the positive electrode sheet; the secondary battery is the above-mentioned secondary battery; the secondary battery is matched with an ultrasonic generator.

[0044] The energy storage device including the above-mentioned secondary battery matched with an ultrasonic generator has a high energy density and cycle life.

[0045] In an embodiment of the present application, the ultrasonic generator is arranged inside the secondary battery, and the ultrasonic generator is connected to the positive connection piece.

[0046] Preferably, the ultrasonic generator is disposed inside the secondary battery, which helps the ultrasonic wave to better perform ultrasonic treatment on the positive electrode tab through the positive electrode connecting piece, so as to better conduct to the positive electrode plate.

[0047] In an embodiment of the present application, the ultrasonic generator is disposed outside the secondary battery, and the ultrasonic generator is directly or indirectly connected to the positive electrode terminal; wherein, the ultrasonic generator is disposed inside the battery module, or the ultrasonic generator is disposed outside the battery module and inside the battery pack, or the ultrasonic generator is disposed outside the battery pack.

[0048] Preferably, when the ultrasonic generator is disposed outside the secondary battery, adopting the above-mentioned position setting helps the ultrasonic wave to better perform ultrasonic treatment on the positive electrode terminal, so as to better conduct to the positive electrode plate.

[0049] When the ultrasonic generator is disposed inside the battery module, the ultrasonic generator is directly connected to the positive electrode terminal; or, the ultrasonic generator is connected to the bus bar through a wire harness and then connected to the tab of each secondary battery, and then connected to the positive electrode terminal.

[0050] When the ultrasonic generator is disposed outside the battery module and inside the battery pack, the ultrasonic generator is disposed on the end plate, connected to the bus bar through a wire harness and then connected to the tab of each secondary battery, and then connected to the positive electrode terminal.

[0051] When the ultrasonic generator is disposed outside the battery pack, the ultrasonic generator is disposed on the maintenance panel, and at the same time, a connecting device is added to connect to the end plates of each battery module, connected to the bus bar through a wire harness and then connected to the tab of each secondary battery, and then connected to the positive electrode terminal.

[0052] In another typical embodiment of the present application, a lithium supplement method for the above-mentioned secondary battery is provided. The secondary battery includes a positive electrode terminal and a positive electrode plate. The positive electrode terminal is disposed on the top cover of the secondary battery. The positive electrode terminal is connected to the positive electrode connecting piece, and the positive electrode connecting piece is connected to the positive electrode tab on the positive electrode plate; the lithium supplement method includes: matching an ultrasonic generator inside or outside the secondary battery, using the ultrasonic generator to perform ultrasonic treatment on the positive electrode terminal or the positive electrode tab of the secondary battery, dissociating the hydrogen bond organic framework material in the composite positive electrode and releasing the first positive electrode material to realize lithium supplement of the secondary battery.

[0053] By subjecting the positive electrode terminal or positive electrode tab of a secondary battery to ultrasound using an ultrasonic generator, the hydrogen bond organic framework material in the positive electrode sheet can be recombined and dissociated to release the first positive electrode material. The ultrasonic generator can dynamically adjust the ultrasound, thereby better controlling the degree of dissociation of the HOF material, releasing an appropriate amount of the first positive electrode material (i.e., the lithium source), and thus achieving precise lithium supplementation, avoiding the risk of local lithium deposition caused by the one-time release of the lithium source in traditional lithium supplementation methods. In addition, by subjecting the positive electrode terminal or positive electrode tab to ultrasound using the ultrasonic generator, local dissociation of the HOF material in a specific area of the composite positive electrode sheet can be achieved. This local lithium supplementation method can reduce the impact on other parts of the battery, thereby avoiding potential side reactions and damage to the internal structure of the battery, and improving the lithium supplementation efficiency and the overall performance of the battery. The lithium supplementation method of this application avoids the problems of over-lithium supplementation or under-lithium supplementation, ensures lithium balance during battery cycling, and thus improves the cycle stability and safety of the battery.

[0054] In one embodiment of this application, the battery management system is electrically connected to the secondary battery and the ultrasonic generator respectively. The battery management system is used to detect the degree of cell attenuation of the secondary battery and set the frequency, power, and operating time of the ultrasonic generator.

[0055] Linking the battery management system (BMS) with the ultrasonic generator helps to dynamically adjust the frequency, power, and operating time of the ultrasonic generator according to parameters such as the SOC and number of cycles of the secondary battery, thereby facilitating precise lithium supplementation.

[0056] In one embodiment of this application, the ultrasonic generator is started when the capacity of the secondary battery decays to a certain capacity fixed value, where the capacity fixed value is any value within the range of 80% to 90% of the initial capacity value of the secondary battery.

[0057] When the BMS detects that the capacity of the secondary battery decays to any value within the range of 80% to 90% of the initial value, the ultrasonic generator is started, prompting the dissociation of the HOF material and the slow release of the encapsulated high-capacity positive electrode material, thereby releasing lithium ions more timely and maintaining a relatively high capacity level of the secondary battery. For example, when the BMS detects that the capacity decays to 95%, 90%, 85%, 80% of the initial value and starts the ultrasound, the battery capacity after 50 cycles is restored to 98.3%, 92.5%, 88.7%, 83% respectively, thus better improving the cycle life of the battery.

[0058] In an embodiment of the present application, when an ultrasonic generator is externally matched with a secondary battery, the ultrasonic generator is directly or indirectly connected to the positive electrode terminal. The positive electrode terminal of the secondary battery is ultrasonically treated by the ultrasonic generator. The frequency of the ultrasonic generator is 1 - 2 MHz, preferably 1.5 - 2 MHz. The power of the ultrasonic generator is 5 - 15 MPa, preferably 7.5 - 15 MPa, and / or the acting time of the ultrasonic generator is 10 - 120 s, preferably 60 - 120 s. And / or when the ultrasonic generator is internally matched with the secondary battery, the ultrasonic generator is connected to the positive electrode connecting piece, and the positive electrode tab of the secondary battery is ultrasonically treated by the ultrasonic generator. The frequency of the ultrasonic generator is 0.01 - 2 MHz, preferably 0.01 - 0.8 MHz. The power of the ultrasonic generator is 0.01 - 7.5 MPa, preferably 0.01 - 4.5 MPa, and / or the acting time of the ultrasonic generator is 10 - 120 s, preferably 10 - 50 s.

[0059] When an ultrasonic generator is externally matched with a secondary battery, controlling the frequency, power and time of the ultrasonic generator within the above ranges, the ultrasonic wave is conducted to the positive electrode tab through the positive electrode terminal, and then conducted to the positive electrode plate to dissociate the HOF material, so as to better release the first positive electrode material for lithium supplementation. If the frequency of the applied ultrasonic wave is relatively low, only part of the HOF material dissociates; if the frequency is relatively high, the dissociation degree of the HOF material is too high. And the ultrasonic generator is arranged outside the secondary battery, which is easy to install and maintain. Specifically, it is installed outside the battery cell, without large-scale modification of the internal structure of the battery cell, and also helps to ensure the safety and reliability of the battery. The direct or indirect connection between the ultrasonic generator and the positive electrode terminal refers to the foregoing setting method.

[0060] When an ultrasonic generator is internally matched with a secondary battery, controlling the frequency, power and time of the ultrasonic generator within the above ranges, the ultrasonic wave is conducted to the positive electrode plate through the positive electrode tab to dissociate the HOF material, so as to better release the first positive electrode material for lithium supplementation. And the ultrasonic generator is arranged inside the secondary battery, and the lithium supplementation efficiency is higher, which helps to act more precisely on the key parts and reduce the energy loss during the transmission process.

[0061] The beneficial effects of the present application will be further described below in conjunction with embodiments.

[0062] Example 1

[0063] Preparation of the first positive electrode @HOF-TATBDE: Dissolve 50 mg of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 50 mg of the first positive electrode material lithium cobalt oxide material LiCoO2 in 10 mL of the solvent dimethylformamide solution (DMF) as the bottom layer solution. The middle layer solution is a mixed solution of methanol and water (volume ratio of the two is 1:1). The upper layer is n-hexane. Then, after standing at room temperature for 48 h, collect the sample at the interface, wash it 3 times with methanol to remove the residual solvent, and vacuum dry it at 60 °C for 12 h to obtain the composite encapsulation material. Among them, the first positive electrode material is embedded in the pores of the hydrogen bond organic framework material.

[0064] By weight, mix 10 parts of the composite encapsulation material, 88 parts of the second positive electrode material lithium iron phosphate material LiFePO4, 0.8 part of the conductive agent acetylene black, and 1.2 parts of the binder PVDF in sequence, homogenize and coat them to obtain the composite positive electrode sheet.

[0065] Assemble the composite positive electrode sheet, the graphite negative electrode sheet and the ceramic coating separator into an electric core, and then assemble it with the top cover and the outer shell to obtain a secondary battery. Among them, the secondary battery includes a positive electrode terminal and a positive electrode sheet. The positive electrode terminal is arranged on the top cover of the secondary battery, and the positive electrode terminal on the positive electrode terminal is connected to the positive electrode tab on the positive electrode sheet.

[0066] Match an ultrasonic generator outside the secondary battery. The ultrasonic generator is arranged outside the battery pack and is connected to the positive electrode terminal. Use the ultrasonic generator to perform ultrasonic treatment on the positive electrode terminal of the secondary battery. The battery management system (BMS) is electrically connected to the secondary battery and the ultrasonic generator respectively. When the BMS detects that the capacity of the secondary battery decays to 80% of the initial value, start the ultrasonic generator, set the frequency of the ultrasonic generator to 1.5 MHz, the power to 5 MPa, and the action time to 60 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 83% after 50 battery cycles.

[0067] The flow chart of the above secondary battery preparation method - the lithium supplement method of the secondary battery is as Figure 1 shown.

[0068] Example 2

[0069] The difference from Example 1 lies in the preparation of the first positive electrode @HOF-BTB: 80 mg of 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) and 80 mg of the first positive electrode material lithium nickel cobalt manganese oxide material LiNi 0.3 Co 0.3 Mn 0.33 mL of the solvent methanol was added with O2, and then it was transferred to a 20 mL autoclave, heated to 90 °C and reacted for 5 h, taken out from the oven and left standing for 1 - 2 days. It was washed three times with methanol to remove the residual solvent, and vacuum dried at 60 °C for 12 h to obtain the composite encapsulation material.

[0070] When the BMS detects that the capacity of the secondary battery decays to 85% of the initial value, the ultrasonic generator is started, the frequency of the ultrasonic generator is set to 1 MHz, the power is 5 MPa, and the action time is 60 s, so as to promote the dissociation of the HOF material in the composite encapsulation material and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 88.7% after the battery is cycled 50 times.

[0071] Example 3

[0072] The difference from Example 1 lies in the preparation of the first positive electrode @HOF-101: 150 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene H4TBAPy (0.225 mmol) and 150 mg of the first positive electrode material lithium nickel cobalt manganese aluminum material Li[Ni 0.89 Co 0.05 Mn 0.05 Al 0.01 O2 was dissolved in 22.5 mL of DMF solution, 90 mL of methanol was added thereto and stirred for 2 min to obtain a mixture. The mixture was left standing at room temperature for 12 h, the product was collected by centrifugation, washed three times with ethanol, and vacuum dried at 60 °C for 12 h to obtain the composite encapsulation material.

[0073] When the BMS detects that the capacity of the secondary battery decays to 90% of the initial value, the ultrasonic generator is started, the frequency of the ultrasonic generator is set to 2 MHz, the power is 7.5 MPa, and the action time is 90 s, so as to promote the dissociation of the HOF material in the composite encapsulation material and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 93.5% after the battery is cycled 50 times.

[0074] Example 4

[0075] The difference from Example 1 lies in the preparation of the first positive electrode @HOF-102: 200 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene H4TNAPy (0.225 mmol) and 250 mg of the first positive electrode material lithium nickel cobalt manganese aluminum material Li[Ni 0.89 Co 0.05 Mn 0.05 Al 0.01O2 was dissolved in 60 mL of DMF solution to obtain a clear yellow solution. Subsequently, the solution was poured into 160 mL of acetone and stirred to obtain a suspension. The suspension was continuously stirred for 12 h, and the product was collected by centrifugation, washed 4 times with acetone, and dried in vacuo at 60 °C to obtain the composite encapsulation material.

[0076] When the BMS detected that the capacity of the secondary battery had decayed to 90% of the initial value, the ultrasonic generator was started. The frequency of the ultrasonic generator was set to 1 MHz, the power was 5 MPa, and the action time was 60 s, prompting the dissociation of the HOF material in the composite encapsulation material and the slow release of the encapsulated high-capacity first positive electrode material, and timely releasing lithium ions. After 50 cycles of the battery, the capacity was restored to 93.0% respectively.

[0077] Example 5

[0078] The difference from Example 1 lies in the preparation of the first positive electrode @ZJU-HOF-10: Add 20 mg of 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4',6,6'-hexamethyl-2,2'-biphenyl H4TCHB, the first positive electrode material lithium nickel cobalt manganese aluminum material Li[Ni 0.89 Co 0.05 Mn 0.05 Al 0.01 O2 and 8 mL of tetrahydrofuran solution (THF) into a 20 mL vial. After ultrasonic dissolution, the vial was sealed with plastic wrap. After making 5 pores with a needle, the vial was placed in a sealed tank (with a specification of 250 mL) containing 50 mL of dichloromethane and sealed. After standing at room temperature for one week, the composite encapsulation material was obtained at the bottom of the vial.

[0079] When the BMS detected that the capacity of the secondary battery had decayed to 95% of the initial value, the ultrasonic generator was started. The frequency of the ultrasonic generator was set to 1.8 MHz, the power was 6 MPa, and the action time was 80 s, prompting the dissociation of the HOF material in the composite encapsulation material and the slow release of the encapsulated high-capacity first positive electrode material, and timely releasing lithium ions. After 50 cycles of the battery, the capacity was restored to 98.3% respectively.

[0080] Example 6

[0081] The difference from Example 1 lies in that the mass ratio of the first positive electrode material to the hydrogen-bonded organic framework material is 5:1, and finally a composite positive electrode plate and a secondary battery are obtained.

[0082] When the BMS detects that the capacity of the secondary battery has decayed to 80% of the initial value, start the ultrasonic generator, set the frequency of the ultrasonic generator to 1.5 MHz, the power to 5 MPa, and the action time to 60 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 84.5% after 50 battery cycles respectively.

[0083] Example 7

[0084] The difference from Example 1 is that the mass ratio of the first positive electrode material to the hydrogen-bonded organic framework material is 1:2, and finally a composite positive electrode sheet and a secondary battery are obtained.

[0085] When the BMS detects that the capacity of the secondary battery has decayed to 80% of the initial value, start the ultrasonic generator, set the frequency of the ultrasonic generator to 1.5 MHz, the power to 5 MPa, and the action time to 60 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 80.5% after 50 battery cycles respectively.

[0086] Example 8

[0087] The difference from Example 1 is that the mass ratio of the composite encapsulation material to the second positive electrode material is 20:80, and finally a composite positive electrode sheet and a secondary battery are obtained.

[0088] When the BMS detects that the capacity of the secondary battery has decayed to 80% of the initial value, start the ultrasonic generator, set the frequency of the ultrasonic generator to 1.5 MHz, the power to 5 MPa, and the action time to 60 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 85.5% after 50 battery cycles respectively.

[0089] Example 9

[0090] The difference from Example 1 is that the mass ratio of the composite encapsulation material to the second positive electrode material is 3:97, and finally a composite positive electrode sheet and a secondary battery are obtained.

[0091] When the BMS detects that the capacity of the secondary battery has decayed to 80% of the initial value, start the ultrasonic generator, set the frequency of the ultrasonic generator to 1.5 MHz, the power to 5 MPa, and the action time to 60 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 80.8% after 50 battery cycles respectively.

[0092] Example 10

[0093] The difference from Example 1 is that when an ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting piece, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode tab of the secondary battery. When the BMS detects that the capacity of the secondary battery decays to 80% of the initial value, the ultrasonic generator is started. The frequency of the ultrasonic generator is set to 0.01 MHz, the power is 3 MPa, and the action time is 50 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 83.5% after 50 battery cycles respectively.

[0094] Example 11

[0095] The difference from Example 1 is that when an ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting piece, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode tab of the secondary battery. When the BMS detects that the capacity of the secondary battery decays to 80% of the initial value, the ultrasonic generator is started. The frequency of the ultrasonic generator is set to 2.5 MHz, the power is 10 MPa, and the action time is 5 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 80.4% after 50 battery cycles respectively.

[0096] Example 12

[0097] The difference from Example 1 is that when the BMS detects that the capacity of the secondary battery decays to 95% of the initial value, the ultrasonic generator is started. The frequency of the ultrasonic generator is set to 2 MHz, the power is 15 MPa, and the action time is 120 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 98.5% after 50 battery cycles respectively.

[0098] Example 13

[0099] The difference from Example 1 is that when the BMS detects that the capacity of the secondary battery decays to 95% of the initial value, the ultrasonic generator is started. The frequency of the ultrasonic generator is set to 2.5 MHz, the power is 4 MPa, and the action time is 30 s, so as to cause the HOF material in the composite encapsulation material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, release lithium ions in time, and the capacity is restored to 95.5% after 50 battery cycles respectively.

[0100] Comparative Example 1

[0101] Add 1% of a lithium-containing compound to the positive electrode of the lithium-ion battery The overall initial capacity of the lithium-ion battery obtained was increased by 3%. When the battery capacity decayed to 80% of the initial value, after 50 battery cycles, the battery capacity began to decay significantly to 70%.

[0102] Comparative Example 2

[0103] Adding 1% lithium-containing compounds to the positive electrode of lithium-ion batteries The overall initial capacity of the obtained lithium-ion battery increased by 4%. When the battery capacity decayed to 80% of the initial value, the battery capacity retention rate was 75% after 50 battery cycles.

[0104] Test method:

[0105] The secondary batteries of the above embodiments and comparative examples were subjected to performance tests by constant power 1P charging and discharging at 45° C. The test results are shown in Table 1.

[0106] Table 1

[0107]

[0108] It can be seen from Table 1 that although the overall capacity of the lithium-ion battery in Comparative Example 1 is increased by 3%, during the cycle, The decomposition products may react with the electrolyte to affect the cycle stability of the battery. After 50 to 60 cycles, the capacity of the battery begins to decay significantly, and the cycle life is not effectively improved. Although lithium is replenished to a certain extent, due to its own structural characteristics, during the battery charging and discharging process, The structural stability is poor. Therefore, even if the battery capacity is increased by 4% in the early stage, as the number of cycles increases, the material structure gradually collapses, which will cause the battery capacity to drop rapidly and the cycle life improvement effect is not good.

[0109] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0110] In this application, a composite encapsulation material is doped in the composite positive electrode sheet, and a high-capacity first positive electrode material (lithium source material) in the composite encapsulation material is embedded in the pores of a hydrogen-bonded organic framework material (HOF material) with an interpenetrating structure. Under the action of ultrasonic waves, the hydrogen-bonded organic framework material can be dissociated, and the encapsulated lithium source material can be slowly released, so as to supplement lithium during the service period of the secondary battery, effectively avoiding the risk of local lithium precipitation caused by the one-time release of the lithium supplement material. Compared with metal-organic framework materials (MOF materials) and covalent organic framework materials (COF materials), the intermolecular force of HOF materials is weaker, which is more conducive to its dissociation. Moreover, the high-capacity first positive electrode material is encapsulated in the framework and can be effectively protected. Preferably, when the type of the first positive electrode material is within the above range, lithium ions can be better slowly released. The preparation method of this application is simple and has a low cost.

[0111] The above are only examples of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a secondary battery, characterized in that, The preparation method includes: Step S1: embedding the first cathode material into the pores of a hydrogen-bonded organic framework material with an interpenetrating structure to obtain a composite encapsulation material; Step S2: successively mixing, homogenizing, and coating raw materials including the composite encapsulation material and a second cathode material to obtain a composite cathode electrode sheet; under the action of ultrasonic waves, the hydrogen-bonded organic framework material in the composite cathode electrode sheet can dissociate and release the first cathode material to supplement lithium for the secondary battery; and Step S3: assembling components including the composite cathode electrode sheet, a negative electrode sheet, and a separator to obtain a secondary battery; wherein, the first cathode material is any one or more of lithium nickel cobalt manganese oxide material, lithium cobalt oxide material, and lithium nickel cobalt manganese aluminum oxide material; In step S1, the hydrogen-bonded organic framework material is selected from any one or more of HOF-TATB, HOF-BTB, HOF-101, HOF-102, and ZJU-HOF-10; The composite encapsulation material is obtained by mixing and reacting a second raw material including a first raw material corresponding to the hydrogen-bonded organic framework material, the first cathode material, and a solvent; wherein, the first raw material is selected from any one of 1,3,5-triamino-2,4,6-trinitrobenzene, 1,3,5-tris(4-carboxyphenyl)benzene, 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene, and 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4',6,6'-hexamethyl-2,2'-biphenyl.

2. The method for preparing a secondary battery according to claim 1, wherein In step S1, the mass ratio of the first cathode material to the hydrogen-bonded organic framework material is 1-5:

1.

3. The method for preparing a secondary battery according to claim 1 or 2, wherein In step S2, the mass ratio of the composite encapsulation material to the second cathode material is 5-20:80-95; and / or, the second cathode material is any one or more of lithium nickel cobalt manganese oxide material, lithium iron phosphate material, and lithium cobalt oxide material.

4. The method for preparing a secondary battery according to claim 1 or 2, characterized in that, In step S2, the rotation speed of the mixing is 50-200 rpm, and / or, the mixing time is 5-30 min.

5. A secondary battery, comprising a positive electrode sheet, a negative electrode sheet and a separator, characterized in that, The secondary battery is prepared by the preparation method of the secondary battery according to any one of claims 1 to 4; wherein, the cathode electrode sheet includes a composite encapsulation material and a second cathode material; the composite encapsulation material includes a first cathode material and a hydrogen-bonded organic framework material with an interpenetrating structure; the first cathode material is embedded in the pores of the hydrogen-bonded organic framework material.

6. An energy storage device, the energy storage device comprising a battery pack, the battery pack comprising one or more battery modules, each of the battery modules independently comprising one or more secondary batteries, each of the secondary batteries independently comprising a positive electrode terminal, a positive electrode plate and a positive electrode connection piece, the positive electrode terminal being disposed on the top cover of the secondary battery, the positive electrode terminal being connected to the positive electrode connection piece, and the positive electrode connection piece being connected to a positive electrode tab on the positive electrode plate; characterized in that, The secondary battery is the secondary battery according to claim 5; the secondary battery is equipped with an ultrasonic generator.

7. The energy storage device according to claim 6, wherein The ultrasonic generator is arranged inside the secondary battery, and the ultrasonic generator is connected to the positive electrode connecting piece.

8. The energy storage device according to claim 6, characterized in that, The ultrasonic generator is arranged outside the secondary battery, and the ultrasonic generator is directly or indirectly connected to the positive electrode terminal; wherein, the ultrasonic generator is arranged inside the battery module, or the ultrasonic generator is arranged outside the battery module and inside the battery pack, or the ultrasonic generator is arranged outside the battery pack.

9. A method for lithium supplementation of the secondary battery according to claim 5, wherein the secondary battery includes a positive electrode terminal, a positive electrode plate, and a positive electrode connection piece, the positive electrode terminal is disposed on the top cover of the secondary battery, the positive electrode terminal is connected to the positive electrode connection piece, and the positive electrode connection piece is connected to a positive electrode tab on the positive electrode plate; characterized in that, The lithium supplementation method includes: Match an ultrasonic generator inside or outside the secondary battery, and use the ultrasonic generator to perform ultrasonic treatment on the positive electrode terminal or the positive electrode tab of the secondary battery, so that the hydrogen-bonded organic framework material in the composite positive electrode sheet dissociates and releases the first positive electrode material, thereby realizing lithium supplementation for the secondary battery.

10. The method for supplementing lithium of the secondary battery according to claim 9, wherein The battery management system is electrically connected to the secondary battery and the ultrasonic generator respectively. The battery management system is used to detect the degree of cell attenuation of the secondary battery, and set the frequency, power, and action time of the ultrasonic generator.

11. The method for lithium supplementation of a secondary battery according to claim 10, wherein Start the ultrasonic generator when the capacity of the secondary battery decays to a certain capacity fixed value, where the capacity fixed value is any value within the range of 80% to 90% of the initial capacity value of the secondary battery.

12. The method for lithium supplementation of the secondary battery according to claim 11, wherein When the ultrasonic generator is matched outside the secondary battery, the ultrasonic generator is directly or indirectly connected to the positive electrode terminal. Use the ultrasonic generator to perform ultrasonic treatment on the positive electrode terminal of the secondary battery. The frequency of the ultrasonic generator is 1 to 2 MHz, the power of the ultrasonic generator is 5 to 15 MPa, and / or the action time of the ultrasonic generator is 60 to 120 s; And / or, when the ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting piece, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode tab of the secondary battery. The frequency of the ultrasonic generator is 0.01 to 2 MHz, the power of the ultrasonic generator is 0.01 to 7.5 MPa, and / or the action time of the ultrasonic generator is 10 to 120 s.

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