Secondary battery, preparation method thereof, lithium supplementing method and energy storage equipment

Abstract

The invention provides a secondary battery, a preparation method thereof, a lithium supplementing method and energy storage equipment. The preparation method comprises the following steps: embedding a first positive electrode material into pores of a hydrogen bond organic framework material with an interpenetrating structure to obtain a composite packaging material; sequentially mixing, homogenizing and coating raw materials comprising the composite packaging material and a second positive electrode material to obtain a composite positive electrode plate; under the action of ultrasonic waves, the hydrogen bond organic framework material in the composite positive pole piece can be dissociated and release the first positive pole material so as to supplement lithium for the secondary battery; and assembling the assembly comprising the composite positive pole piece, the negative pole piece and the diaphragm to obtain the secondary battery, wherein the first positive electrode material is any one or more of a nickel cobalt lithium manganate material, a lithium cobalt oxide material and a nickel cobalt manganese aluminum lithium material. According to the secondary battery, the hydrogen bond organic framework material in the composite positive pole piece is dissociated under the action of ultrasonic waves, and the packaged lithium source material is slowly released, so that effective lithium supplement is realized.

Description

Technical Field

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

[0002] Secondary batteries have been widely used due to their high energy density and long cycle life. However, secondary batteries will inevitably suffer lithium loss during the cycle, mainly due to the decomposition of the electrolyte, the formation of SEI (solid electrolyte interface) film, and the instability of the lithium metal negative electrode. These processes not only lead to the attenuation of battery capacity, but also induce irreversible chemical changes, reducing the cycle life and safety of the battery. Therefore, lithium replenishment technology is usually used for lithium replenishment.

[0003] However, current lithium replenishment technologies (such as pre-lithiation and positive electrode lithium replenishers) 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, the pre-lithiation technology requires the additional embedding of lithium sources or lithium metal foils during the battery manufacturing process, and then the lithium is released from the lithium source and replenished into the battery through a specific process. This process not only increases the difficulty of battery manufacturing, but may also introduce new instability factors, such as the uneven distribution of lithium metal foil inside the battery, affecting the performance and safety of the battery. The pre-lithiation technology that uses lithium metal as a lithium replenishment source greatly increases the production cost due to the high price of lithium metal itself and the requirement for a strict water-free and oxygen-free environment during the manufacturing and storage processes. In addition, some lithium replenishment technologies require the use of expensive equipment and special additives, which further pushes up costs.

[0004] In addition, the one-time release of lithium sources is a common problem in existing lithium replenishment technologies. Although the addition of conventional lithium sources can reduce the initial attenuation of the battery during the formation stage, the capacity will continue to decrease during the battery cycle and lithium replenishment cannot be performed again. At the same time, the one-time release of lithium sources will lead to excessive lithium ion concentration in local areas, thereby forming lithium dendrites inside the battery. Lithium dendrites will not only penetrate the diaphragm, causing internal short circuits in the battery, but may also continue to grow during the battery charging and discharging process, 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, lithium replenishment technology still lacks a dynamic compensation mechanism for on-demand and controllable release of active lithium during the service life of the battery, making it difficult to achieve real-time matching of lithium loss and replenishment. Summary of the invention

[0005] The main purpose of the present invention is to provide a secondary battery and its preparation method, lithium replenishment method and energy storage device to solve the problems of complex process, high cost and risk of local lithium precipitation caused by one-time release of lithium source in the lithium replenishment technology in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for preparing a secondary battery is provided, and the method comprises: step S1, embedding a first positive electrode material into the pores of a hydrogen-bonded organic framework material having an interpenetrating structure to obtain a composite packaging material; step S2, sequentially mixing, homogenizing and coating the raw materials including the composite packaging material and the second positive electrode material to obtain a composite positive electrode plate; under the action of ultrasonic waves, the hydrogen-bonded organic framework material in the composite positive electrode plate can dissociate and release the first positive electrode material to replenish lithium for the secondary battery; and step S3, assembling components including a composite positive electrode plate, a negative electrode plate and a separator to obtain a secondary battery; wherein the first positive electrode material is any one or more of a nickel cobalt manganese lithium oxide material, a lithium cobalt oxide material and a nickel cobalt manganese aluminum lithium material.

[0007] Further, in the above step S1, the hydrogen-bonding 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 packaging material is obtained by mixing and reacting a first raw material corresponding to the hydrogen-bonding organic framework material, a first positive electrode material and a second raw material of 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.

[0008] Furthermore, in the above step S1, the mass ratio of the first positive electrode material to the hydrogen-bonding organic framework material is 1-5:1.

[0009] Furthermore, in the above step S2, the mass ratio of the composite packaging 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.

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

[0011] According to another aspect of the present invention, a secondary battery is provided, comprising a positive electrode plate, a negative electrode plate and a separator, and the secondary battery is prepared by the above-mentioned secondary battery preparation method; wherein the positive electrode plate comprises a composite packaging material and a second positive electrode material; the composite packaging material comprises a first positive electrode material and a hydrogen-bonded organic framework material having an interpenetrating structure; the first positive electrode material is embedded in the pores of the hydrogen-bonded organic framework material.

[0012] According to another aspect of the present invention, there is provided an energy storage device, which includes a battery pack, the battery pack includes one or more battery modules, the battery modules independently include one or more secondary batteries, the secondary batteries independently include a positive electrode column, a positive electrode sheet and a positive electrode connecting sheet, the positive electrode column is arranged on the top cover of the secondary battery, the positive electrode column is connected to the positive electrode connecting sheet, and the positive electrode connecting sheet is connected to the positive electrode ear on the positive electrode sheet; the secondary battery is the above-mentioned secondary battery; the secondary battery is matched with an ultrasonic generator.

[0013] Furthermore, the ultrasonic generator is arranged inside the secondary battery, and the ultrasonic generator is connected to the positive electrode connecting sheet.

[0014] Furthermore, the ultrasonic generator is arranged outside the secondary battery, and the ultrasonic generator is directly or indirectly connected to the positive electrode column; 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.

[0015] According to another aspect of the present invention, a method for replenishing lithium of the above-mentioned secondary battery is provided, the secondary battery comprising a positive electrode column, a positive electrode sheet and a positive electrode connecting sheet, the positive electrode column is arranged on the top cover of the secondary battery, the positive electrode column is connected to the positive electrode connecting sheet, and the positive electrode connecting sheet is connected to the positive electrode tab on the positive electrode sheet; the lithium replenishing method comprises: matching an ultrasonic generator inside or outside the secondary battery, using the ultrasonic generator to ultrasonically perform ultrasound on the positive electrode column or the positive electrode tab of the secondary battery, so that the hydrogen bond organic framework material in the composite positive electrode sheet is dissociated and the first positive electrode material is released, thereby realizing lithium replenishment of the secondary battery.

[0016] Furthermore, 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 attenuation degree of the secondary battery cells and set the frequency, power and action time of the ultrasonic generator.

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

[0018] Further, when an ultrasonic generator is matched outside the secondary battery, the ultrasonic generator is directly or indirectly connected to the positive electrode pole, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode pole of the secondary battery, the frequency of the ultrasonic generator is 1~2MHz, the power of the ultrasonic generator is 5~15MPa, and / or the action time of the ultrasonic generator is 60~120s; and / or, when the ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting sheet, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode ear of the secondary battery, the frequency of the ultrasonic generator is 0.01~2MHz, the power of the ultrasonic generator is 0.01~7.5MPa, and / or the action time of the ultrasonic generator is 10~120s.

[0019] By applying the technical solution of the present invention, the beneficial effects of the present application are as follows: the present application dopes a composite packaging material in a composite positive electrode plate, and a high-capacity first positive electrode material (lithium source material) in the composite packaging material is embedded in the pores of a hydrogen-bonded organic framework material (HOF material) having an interpenetrating structure. Under the action of ultrasound, the hydrogen-bonded organic framework material can be dissociated, and the encapsulated lithium source material can be slowly released, thereby replenishing lithium during the service of the secondary battery, and effectively avoiding the risk of local lithium precipitation caused by the one-time release of the lithium replenishment material. Compared with metal organic framework materials (MOF materials) and covalent organic framework materials (COF materials), the molecular forces of HOF materials are weaker, which is more conducive to their 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 release lithium ions. The preparation method of the present application is simple and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A schematic flow chart of a secondary battery preparation method and a secondary battery lithium replenishment method according to Example 1 of the present application is shown. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] As analyzed in the background technology of this application, the lithium replenishment technology in the prior art has the problems of complex process, high cost, and the risk of local lithium precipitation caused by the one-time release of lithium source. In order to solve the above problems, this application provides a secondary battery and its preparation method and lithium replenishment method.

[0024] In a typical embodiment of the present application, a method for preparing a secondary battery is provided, the method comprising: step S1, embedding a first positive electrode material into the pores of a hydrogen-bonded organic framework material having an interpenetrating structure to obtain a composite packaging material; step S2, sequentially mixing, homogenizing and coating the raw materials including the composite packaging material and the second positive electrode material to obtain a composite positive electrode plate; under the action of ultrasonic waves, the hydrogen-bonded organic framework material in the composite positive electrode plate can dissociate and release the first positive electrode material to replenish lithium for the secondary battery; and step S3, assembling components including a composite positive electrode plate, a negative electrode plate and a separator to obtain a secondary battery; wherein the first positive electrode material is any one or more of a nickel cobalt manganese lithium oxide material, a lithium cobalt oxide material and a nickel cobalt manganese aluminum lithium material.

[0025] The present application dopes a composite packaging material into a composite positive electrode plate, and the high-capacity first positive electrode material (lithium source material) in the composite packaging material is embedded in the pores of a hydrogen-bonded organic framework material (HOF material) with an interpenetrating structure. Under the action of ultrasound, the hydrogen-bonded organic framework material can be dissociated, and the encapsulated lithium source material can be slowly released, thereby replenishing lithium during the service of the secondary battery, and effectively avoiding the risk of local lithium precipitation caused by the one-time release of the lithium replenishment material. Compared with metal organic framework materials (MOF materials) and covalent organic framework materials (COF materials), the molecular forces of HOF materials are weaker, which is more conducive to their 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 release lithium ions. The preparation method of the present application is simple and low in cost.

[0026] Among them, the interpenetrating structure of HOF materials refers to the fact that in the crystal structure of HOF materials, two or more independent three-dimensional frameworks interpenetrate each other through non-covalent interactions (such as hydrogen bonds, π-π stacking or van der Waals forces) to form a spatially interwoven network. The interpenetrating structure can better 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-bonding 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 packaging material is obtained by mixing and reacting a first raw material corresponding to the hydrogen-bonding organic framework material, a first positive electrode material and a second raw material of 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), and 3,3',5,5'-tetrakis(4-carboxyphenyl)-2,2',4,4'6,6'-hexamethyl-2,2'-biphenyl (H4TCHB).

[0028] The preferred method for preparing the composite packaging material is as follows:

[0029] Preparation of the first positive electrode @HOF-TATBDE: Synthesized by diffusion method, 50 mg of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and the first positive electrode material were dissolved in 10 mL of dimethylformamide solution (DMF) as the bottom solution. The middle solution was a mixed solution of methanol and water (the volume ratio of the two was 1:1). The upper layer was n-hexane, and then after standing at room temperature for 48 hours, the sample at the interface was collected and washed with methanol 3 times to remove the residual solvent, and vacuum dried at 60°C for 12 hours to obtain a composite packaging material.

[0030] Preparation of the first cathode @HOF-BTB: 80 mg of 1,3,5-tris(4-carboxyphenyl)benzene (H3BTB) and the first cathode material were added to 3 mL of solvent methanol, then transferred to a 20 mL autoclave, heated to 90 ° C for 5 h, removed from the oven and left to stand for 1 to 2 days. Washed with methanol 3 times to remove the residual solvent, and vacuum dried at 60 ° C for 12 h to obtain a composite packaging material.

[0031] Preparation of the first cathode @HOF-101: 150 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene H4TBAPy (0.225 mmol) and the first cathode material were 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 placed 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 a composite packaging material.

[0032] Preparation of the first cathode @HOF-102: 200 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene H4TNAPy (0.225 mmol) and the first cathode material were dissolved in 60 mL of DMF solution to obtain a clear yellow solution, which was then poured into 160 mL of acetone and stirred to obtain a suspension. The suspension was stirred for 12 h, the product was collected by centrifugation, washed with acetone 4 times, and vacuum dried at 60 ° C to obtain a 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) to a 20 mL vial, and seal it with plastic wrap after ultrasonic dissolution. After piercing 5 holes with a needle, the vial is placed in a sealed can (250 mL) filled with 50 mL of dichloromethane and sealed. After being placed at room temperature for one week, a composite packaging material is obtained at the bottom of the vial.

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

[0035] The mass ratio of the first cathode material and the hydrogen-bonded organic framework material is preferably within the above range, which not only helps the high-capacity first cathode material to be fully and evenly embedded in the pores of the HOF material, reducing material waste or excessive packaging resulting in decreased reactivity, but also helps to release lithium source materials by dissociating the HOF material during battery service to better match the lithium loss of the battery, thereby achieving a better lithium replenishment effect. At the same time, the stability of the HOF material helps to better protect the first cathode material during the battery cycle and reduce the inactive consumption of lithium ions.

[0036] In one embodiment of the present application, in the above step S2, the mass ratio of the composite packaging material and 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 packaging material and 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, and the sustained release of the first positive electrode material in the composite packaging material during the service of the battery helps to further compensate for lithium loss. At the same time, the second positive electrode material maintains its original characteristics and improves the cycle stability of the battery together with the composite packaging material.

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

[0039] The mixing speed and time are preferably within the above ranges, which helps to fully mix the composite packaging material and the second positive electrode material, thereby facilitating more uniform subsequent coating.

[0040] In order to better match the composite positive electrode plate, it is preferred that in the above step S3, the negative electrode plate is a graphite negative electrode plate and / or a silicon-based negative electrode plate; and / or the separator is selected from any one or more of polyethylene, polypropylene and ceramic coating separator. The positive electrode current collector can be any material suitable for being used as a positive electrode current collector for lithium-ion batteries. For example, the positive electrode current collector can include but is not limited to metal foil, and more specifically can include but is not limited to aluminum foil.

[0041] In another typical embodiment of the present application, a secondary battery is provided, comprising a positive electrode plate, a negative electrode plate and a separator, and the secondary battery is prepared by the above-mentioned secondary battery preparation method; wherein the positive electrode plate comprises a composite packaging material and a second positive electrode material; the composite packaging material comprises a first positive electrode material and a hydrogen-bonded organic framework material having an interpenetrating structure; the first positive electrode material is embedded in the pores of the hydrogen-bonded organic framework material.

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

[0043] In 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, the battery modules independently include one or more secondary batteries, the secondary batteries independently include a positive electrode column, a positive electrode sheet and a positive electrode connecting sheet, the positive electrode column is arranged on the top cover of the secondary battery, the positive electrode column is connected to the positive electrode connecting sheet, and the positive electrode connecting sheet is connected to the positive electrode ear 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 secondary battery matched with the ultrasonic generator has higher energy density and cycle life.

[0045] In one embodiment of the present application, the ultrasonic generator is disposed inside the secondary battery, and the ultrasonic generator is connected to the positive electrode connecting sheet.

[0046] Preferably, the ultrasonic generator is disposed inside the secondary battery, which helps the ultrasonic wave to better transmit the ultrasonic wave to the positive electrode tab through the positive electrode connecting sheet, thereby better transmitting the ultrasonic wave to the positive electrode sheet.

[0047] In one embodiment of the present application, an ultrasonic generator is disposed outside the secondary battery, and the ultrasonic generator is directly or indirectly connected to the positive electrode pole; 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] When the ultrasonic generator is preferably disposed outside the secondary battery, the above-described position is adopted to help the ultrasonic wave better ultrasonicate the positive electrode column, thereby better transmitting the ultrasonic wave to the positive electrode sheet.

[0049] When the ultrasonic generator is set in the battery module, the ultrasonic generator is directly connected to the positive electrode pole; alternatively, the ultrasonic generator is connected to the busbar through a wiring harness and connected to the bar of each secondary battery, and then connected to the positive electrode pole.

[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 busbar through a wiring harness and connected to the tab of each secondary battery, and then connected to the positive electrode column.

[0051] When the ultrasonic generator is set outside the battery pack, it is set on the inspection panel, and a connecting device is added to connect to the end plates of each battery module, connected to the busbar through the wiring harness and connected to the bar of each secondary battery, and then connected to the positive electrode column.

[0052] In another typical embodiment of the present application, a method for replenishing lithium of the above-mentioned secondary battery is provided, the secondary battery includes a positive electrode column and a positive electrode sheet, the positive electrode column is arranged on the top cover of the secondary battery, the positive electrode column is connected to the positive electrode connecting sheet, and the positive electrode connecting sheet is connected to the positive electrode tab on the positive electrode sheet; the lithium replenishing method includes: matching an ultrasonic generator inside or outside the secondary battery, using the ultrasonic generator to ultrasonicate the positive electrode column or the positive electrode tab of the secondary battery, dissociating the hydrogen bond organic framework material in the composite positive electrode sheet and releasing the first positive electrode material, so as to achieve lithium replenishment of the secondary battery.

[0053] By ultrasonicating the positive pole column or positive pole ear of the secondary battery with an ultrasonic generator, the hydrogen-bonded organic framework material in the composite positive pole piece can be dissociated and the first positive electrode material can be released. The ultrasonic wave can be dynamically adjusted to better control the degree of dissociation of the HOF material, thereby releasing an appropriate amount of the first positive electrode material (i.e., lithium source), thereby achieving precise lithium replenishment, and avoiding the risk of local lithium precipitation caused by the one-time release of the lithium source in the traditional lithium replenishment method. In addition, by ultrasonicating the positive pole column or positive pole ear with an ultrasonic generator, the local dissociation of the HOF material in a specific area of ​​the composite positive pole piece can be achieved. This local lithium replenishment 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, thereby improving the lithium replenishment efficiency and the overall performance of the battery. The lithium replenishment method of the present application avoids the problem of excessive or insufficient lithium replenishment, ensures the lithium balance of the battery during the cycle, and thus improves the cycle stability and safety of the battery.

[0054] In one embodiment of the present application, a battery management system is electrically connected to a secondary battery and an ultrasonic generator, respectively, and the battery management system is used to detect the degree of attenuation of the secondary battery cells and set the frequency, power and action time of the ultrasonic generator.

[0055] The use of a battery management system (BMS) linked to an ultrasonic generator can help dynamically adjust the frequency, power, and action time of the ultrasonic generator according to parameters such as the SOC and number of cycles of the secondary battery, thereby facilitating accurate lithium replenishment.

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

[0057] When the BMS detects that the capacity of the secondary battery has decayed to any value within the range of 80-90% of the initial value, the ultrasonic generator is activated to cause the HOF material to dissociate and slowly release the encapsulated high-capacity positive electrode material, thereby releasing lithium ions more promptly and maintaining a high capacity level of the secondary battery. For example, when the BMS detects that the capacity has decayed to 95%, 90%, 85%, and 80% of the initial value, the ultrasonic wave is activated. After 50 cycles of the battery, the capacity is restored to 98.3%, 92.5%, 88.7%, and 83%, respectively, thereby better improving the cycle life of the battery.

[0058] In one embodiment of the present application, when an ultrasonic generator is matched outside the secondary battery, the ultrasonic generator is directly or indirectly connected to the positive electrode pole, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode pole of the secondary battery, and the frequency of the ultrasonic generator is 1~2MHz, preferably 1.5~2MHz, and the power of the ultrasonic generator is 5~15MPa, preferably 7.5~15MPa, and / or the action time of the ultrasonic generator is 10~120s, preferably 60~120s; and / or, when the ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting sheet, and the ultrasonic generator is used to perform ultrasonic treatment on the positive electrode ear of the secondary battery, and the frequency of the ultrasonic generator is 0.01~2MHz, preferably 0.01~0.8MHz, and the power of the ultrasonic generator is 0.01~7.5MPa, preferably 0.01~4.5MPa, and / or, the action time of the ultrasonic generator is 10~120s, preferably 10~50s.

[0059] When an ultrasonic generator is matched outside the secondary battery, the frequency, power and time of the ultrasonic generator are controlled within the above range, and the ultrasonic wave is transmitted to the positive electrode ear through the positive electrode column, and then transmitted to the positive electrode sheet to dissociate the HOF material, thereby better releasing the first positive electrode material for lithium supplementation. If the frequency of the applied ultrasonic wave is low, only part of the HOF material will dissociate; if the frequency is high, the degree of dissociation of the HOF material will be 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 changes to the internal structure of the battery cell, and it also helps to ensure the safety and reliability of the battery. The ultrasonic generator is directly or indirectly connected to the positive electrode column, refer to the above-mentioned setting method.

[0060] When an ultrasonic generator is matched inside the secondary battery, and the frequency, power and time of the ultrasonic generator are controlled within the above range, the ultrasonic wave is transmitted to the positive electrode through the positive electrode tab to dissociate the HOF material, thereby better releasing the first positive electrode material for lithium replenishment. And the ultrasonic generator is set inside the secondary battery, and the lithium replenishment efficiency is more efficient, which helps to act more accurately on key parts and reduce energy loss during transmission.

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

[0062] Example 1

[0063] Preparation of the first cathode @HOF-TATBDE: 50 mg of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 50 mg of the first cathode material lithium cobalt oxide material LiCoO2 were dissolved in 10 mL of dimethylformamide solution (DMF) as the bottom 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, and then after standing at room temperature for 48 hours, the sample at the interface was collected and washed with methanol 3 times to remove the residual solvent, and vacuum dried at 60 ° C for 12 hours to obtain a composite packaging material. Among them, the first cathode material is embedded in the pores of the hydrogen bonded organic framework material.

[0064] In parts by weight, 10 parts of the composite packaging material, 88 parts of the second positive electrode material lithium iron phosphate material LiFePO4, 0.8 parts of the conductive agent acetylene black, and 1.2 parts of the binder PVDF are sequentially mixed, homogenized and coated to obtain a composite positive electrode sheet.

[0065] The composite positive electrode sheet, the graphite negative electrode sheet and the ceramic coating diaphragm are assembled into a battery cell, and then assembled with the top cover and the outer shell to obtain a secondary battery. The secondary battery includes a positive electrode column and a positive electrode sheet, the positive electrode column is arranged on the top cover of the secondary battery, and the positive electrode column is connected to the positive electrode ear on the positive electrode sheet.

[0066] An ultrasonic generator is matched outside the secondary battery. The ultrasonic generator is set outside the battery pack and connected to the positive electrode column. The ultrasonic generator is used to perform ultrasound on the positive electrode column 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 has decayed to 80% of the initial value, the ultrasonic generator is started. The frequency of the ultrasonic generator is set to 1.5MHz, the power is 5MPa and the action time is 60s, which promotes the dissociation of the HOF material in the composite packaging material and slowly releases the packaged high-capacity first positive electrode material, releasing lithium ions in time, and the capacity is restored to 83% after the battery is cycled 50 times.

[0067] The above secondary battery preparation method - secondary battery lithium replenishment method flow diagram, such as Figure 1 shown.

[0068] Example 2

[0069] The difference from Example 1 is that 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 0.3O2 was added to 3 mL of methanol solvent, then transferred to a 20 mL autoclave, heated to 90 ° C for 5 h, taken out of the oven and left to stand for 1 to 2 days. It was washed with methanol three times to remove the residual solvent, and vacuum dried at 60 ° C for 12 h to obtain a composite packaging material.

[0070] When the BMS detects that the capacity of the secondary battery has decayed to 85% of the initial value, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1 MHz, 5 MPa and 60 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 88.7%.

[0071] Example 3

[0072] The difference from Example 1 is that 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 nickel-cobalt-manganese-aluminum-lithium 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 placed 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 a composite packaging material.

[0073] When the BMS detects that the capacity of the secondary battery has decayed to 90% of the initial value, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 2 MHz, 7.5 MPa and 90 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 93.5%.

[0074] Example 4

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

[0076] When the BMS detects that the capacity of the secondary battery has decayed to 90% of the initial value, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1 MHz, 5 MPa and 60 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 93.0%.

[0077] Example 5

[0078] The difference from Example 1 is that the first positive electrode @ZJU-HOF-10 is prepared by adding 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 nickel cobalt manganese aluminum lithium material Li[Ni 0.89 Co 0.05 Mn 0.05 Al 0.01 ]O2 and 8mL of tetrahydrofuran solution (THF), ultrasonically dissolve, seal with plastic wrap, pierce 5 holes with a needle, and seal the vial in a sealed can (250mL) filled with 50mL of dichloromethane. After being placed at room temperature for one week, a composite packaging material is obtained at the bottom of the vial.

[0079] When the BMS detects that the capacity of the secondary battery has decayed to 95% of the initial value, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1.8 MHz, 6 MPa and 80 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 98.3%.

[0080] Example 6

[0081] The difference from Example 1 is 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 sheet 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, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1.5 MHz, 5 MPa and 60 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 84.5%.

[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, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1.5 MHz, 5 MPa and 60 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 80.5%.

[0086] Example 8

[0087] The difference from Example 1 is that the mass ratio of the composite packaging 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, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1.5 MHz, 5 MPa and 60 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 85.5%.

[0089] Example 9

[0090] The difference from Example 1 is that the mass ratio of the composite packaging 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, the ultrasonic generator is started and the frequency, power and action time of the ultrasonic generator are set to 1.5 MHz, 5 MPa and 60 s, which causes the HOF material in the composite packaging material to dissociate and slowly release the encapsulated high-capacity first positive electrode material, releasing lithium ions in time. After the battery is cycled 50 times, the capacity is restored to 80.8%.

[0092] Example 10

[0093] The difference from Example 1 is that when the ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting sheet, and the ultrasonic generator is used to perform ultrasound 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, and the frequency of the ultrasonic generator is set to 0.01MHz, the power is 3MPa and the action time is 50s, so as to cause the HOF material in the composite packaging 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 the battery is cycled 50 times.

[0094] Embodiment 11

[0095] The difference from Example 1 is that when the ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting sheet, and the ultrasonic generator is used to perform ultrasound 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, and the frequency of the ultrasonic generator is set to 2.5MHz, the power is 10MPa and the action time is 5s, so as to cause the HOF material in the composite packaging 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 the battery is cycled 50 times.

[0096] Example 12

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

[0098] Example 13

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

[0100] Comparative Example 1

[0101] Adding 1% lithium-containing compounds to the positive electrode of lithium-ion batteries 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] The present application dopes a composite packaging material into a composite positive electrode plate, and the high-capacity first positive electrode material (lithium source material) in the composite packaging material is embedded in the pores of a hydrogen-bonded organic framework material (HOF material) with an interpenetrating structure. Under the action of ultrasound, the hydrogen-bonded organic framework material can be dissociated, and the encapsulated lithium source material can be slowly released, thereby replenishing lithium during the service of the secondary battery, and effectively avoiding the risk of local lithium precipitation caused by the one-time release of the lithium replenishment material. Compared with metal organic framework materials (MOF materials) and covalent organic framework materials (COF materials), the molecular forces of HOF materials are weaker, which is more conducive to their 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 release lithium ions. The preparation method of the present application is simple and low in cost.

[0111] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a secondary battery, characterized in that: The preparation method comprises: 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 packaging material; Step S2, mixing, homogenizing and coating the raw materials including the composite packaging material and the second positive electrode material in sequence to obtain a composite positive electrode plate; under the action of ultrasound, the hydrogen-bonded organic framework material in the composite positive electrode plate can dissociate and release the first positive electrode material to replenish lithium for the secondary battery; and Step S3, assembling the components including the composite positive electrode plate, the negative electrode plate and the separator to obtain a secondary battery; wherein the first positive electrode material is any one or more of nickel cobalt manganese lithium oxide material, lithium cobalt oxide material and nickel cobalt manganese aluminum lithium material.

2. The method for preparing a secondary battery according to claim 1, characterized in that: In the step S1, the hydrogen-bonding 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 packaging material is obtained by mixing and reacting a first raw material corresponding to the hydrogen-bonded organic framework material, the first positive electrode material and a second raw material of 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.

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

1.

4. The method for preparing a secondary battery according to any one of claims 1 to 3, characterized in that: In the step S2, the mass ratio of the composite packaging 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.

5. The method for preparing a secondary battery according to any one of claims 1 to 3, characterized in that: In step S2, the mixing speed is 50-200 rpm, and / or the mixing time is 5-30 min.

6. 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 secondary battery preparation method described in any one of claims 1 to 5; wherein the positive electrode plate comprises a composite packaging material and a second positive electrode material; the composite packaging material comprises a first positive electrode material and a hydrogen-bonded organic framework material having an interpenetrating structure; and the first positive electrode material is embedded in the pores of the hydrogen-bonded organic framework material.

7. An energy storage device, comprising a battery pack, the battery pack comprising one or more battery modules, the battery modules each independently comprising one or more secondary batteries, the secondary batteries each independently comprising a positive electrode column, a positive electrode sheet and a positive electrode connecting sheet, the positive electrode column being arranged on a top cover of the secondary battery, the positive electrode column being connected to the positive electrode connecting sheet, and the positive electrode connecting sheet being connected to a positive electrode ear on the positive electrode sheet; characterized in that: The secondary battery is the secondary battery according to claim 6; the secondary battery is matched with an ultrasonic generator.

8. The energy storage device according to claim 7, characterized in that: The ultrasonic generator is arranged inside the secondary battery and is connected to the positive electrode connecting sheet.

9. The energy storage device according to claim 7, 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 column; 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.

10. A lithium replenishing method for a secondary battery according to claim 6, wherein the secondary battery comprises a positive electrode column, a positive electrode sheet and a positive electrode connecting sheet, wherein the positive electrode column is arranged on the top cover of the secondary battery, the positive electrode column is connected to the positive electrode connecting sheet, and the positive electrode connecting sheet is connected to the positive electrode ear on the positive electrode sheet; characterized in that: The lithium supplementation method comprises: An ultrasonic generator is matched inside or outside the secondary battery, and the ultrasonic generator is used to perform ultrasound on the positive electrode column or the positive electrode ear of the secondary battery to dissociate the hydrogen bond organic framework material in the composite positive electrode plate and release the first positive electrode material, thereby achieving lithium replenishment of the secondary battery.

11. The lithium replenishing method for a secondary battery according to claim 10, characterized in that: The battery management system is electrically connected to the secondary battery and the ultrasonic generator respectively, and is used to detect the attenuation degree of the cells of the secondary battery and set the frequency, power and action time of the ultrasonic generator.

12. The lithium replenishing method for a secondary battery according to claim 11, characterized in that: The ultrasonic generator is started when the capacity of the secondary battery decays to a certain capacity setting value, wherein the capacity setting value is any value within a range of 80-90% of the initial capacity value of the secondary battery.

13. The lithium replenishing method for a secondary battery according to claim 12, characterized in that: When the ultrasonic generator is matched outside the secondary battery, the ultrasonic generator is directly or indirectly connected to the positive electrode column, and the ultrasonic generator is used to perform ultrasound on the positive electrode column 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 the ultrasonic generator is matched inside the secondary battery, the ultrasonic generator is connected to the positive electrode connecting plate, and the ultrasonic generator is used to perform ultrasound on the positive electrode tab of the secondary battery, the frequency of the ultrasonic generator is 0.01~2MHz, the power of the ultrasonic generator is 0.01~7.5MPa, and / or the action time of the ultrasonic generator is 10~120s.

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