Lithium extraction and deintercalation electrode plate and manufacturing method therefor and use thereof

Abstract

A lithium extraction and deintercalation electrode plate and a manufacturing method therefor and a use thereof. An active layer of the lithium extraction and deintercalation electrode plate comprises a lithium-rich positive electrode material after delithiation and alginate. The alginate is used for improving the hydrophilicity of the electrode plate, and at the same time, a hydrogel structure is produced by the alginate and dissolved-out metal ions under the gelation effect generated in a water flow environment during a lithium intercalation and deintercalation cycle, so that lithium ion transport can be enhanced; the mechanical properties of the electrode plate can be improved, and the stability thereof in all directions can be maintained, thereby solving the problems of falling-off of substances and poor stable lithium-ion transport capability caused by insufficient mechanical stability of the electrode plate during long-term use.

Description

A lithium extraction and deintercalation plate and its preparation method and use Technical Field

[0001] The present invention belongs to the technical field of lithium resource extraction, and relates to a lithium extraction and deintercalation plate, a preparation method thereof, and uses thereof. Background Art

[0002] The global transportation sector is undergoing a new energy transformation. Lithium-ion batteries, as a new energy source, are receiving more and more attention, which directly drives the demand for lithium resources.

[0003] Direct lithium extraction from electro-deintercalation is an effective method for extracting lithium resources. It has attracted attention from the industry for its green, efficient, environmentally friendly, and water-efficient characteristics. The current trend is to extract lithium directly from salt lake brines in salt lake areas. When applied in salt lake brines, a key technology is to ensure the stable performance of the electro-deintercalation plates. This requires good mechanical and performance stability over long-term use.

[0004] CN113293285A provides a solution for improving the lithium ion transport capacity of positive electrode materials through inorganic modification. The solution is obtained by mixing the electrode active material with lithium oxide through ball milling and then calcining to obtain a lithium oxide-modified electrode active material. The material is then formulated into a slurry to form an active layer, thereby obtaining a fast ion conductor modified electrode. The solution utilizes the pre-lithiation effect of lithium oxide during the lithium extraction process to effectively improve the selectivity and cycle performance of the electrode, and can efficiently process brine of different grades. However, this method requires high-temperature calcination and strong acid treatment, and the control effect of the inorganic coating layer is difficult to be consistent.

[0005] In addition to requiring the plate to have good mechanical stability during long-term use, considering that the electro-deintercalation plate is always in a salty water environment, it is necessary to improve the hydrophilicity of the plate, which helps to improve the environmental adaptability of the plate and enhance the lithium ion transmission efficiency when the plate is working.

[0006] Therefore, new technical solutions still need to be developed to enable the plates to have both excellent mechanical and performance stability and maintain the ability to stably transmit lithium ions.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] In view of the problems existing in the prior art, the purpose of the present disclosure is to provide a lithium extraction and deintercalation plate and its preparation method and use, wherein the active layer of the lithium extraction and deintercalation plate contains a lithium-rich positive electrode material and alginate after delithiation. The present disclosure utilizes a large number of carboxylate groups in alginate to improve the hydrophilicity of the plate, so as to facilitate the adaptability of the plate in salt lake brine. In addition, since the positive electrode material in the plate will undergo dissolution of multivalent ions when deintercalating lithium in a brine environment (this is also one of the failure modes of lithium-ion batteries), and the brine also contains a large amount of multivalent transition metal ions, these multivalent ions will form a hydrogel structure based on dynamic covalent bonds with alginate. The water channels in the gel can enhance the transmission of lithium ions, and the three-dimensional network of the gel can also improve the mechanical properties of the plate and maintain the stability of the plate in all directions, thereby solving the problems of material shedding and poor stable lithium ion transmission capacity caused by the low mechanical stability of the plate during long-term use.

[0010] To achieve this goal, the present disclosure adopts the following technical solutions:

[0011] In a first aspect, the present disclosure provides a lithium extraction and deintercalation plate, which includes a current collector and an active layer disposed on the current collector; the active layer includes a positive electrode material after delithiation and alginate.

[0012] In the present disclosure, the positive electrode material after delithiation is mixed with hydrophilic alginate to form the active layer of the plate, and the hydrophilicity of the plate is enhanced by using alginate. Then, the divalent / trivalent metal ions in the brine and those dissolved from the positive electrode material are cross-linked with the alginate to obtain a hydrogel structure, so as to achieve the purpose of enhancing the mechanical and mechanical properties of the plate. In addition, the three-dimensional channels of the hydrogel objectively contribute to the transmission of lithium ions, thereby improving the stable transmission capacity of lithium ions of the plate during long-term use. The solution provided by the present disclosure has low energy consumption, makes full use of the physicochemical properties of each substance, is low in cost, is suitable for large-scale production, and solves the problems of material shedding and poor stable transmission capacity of lithium ions caused by the low mechanical stability of the plate during long-term use.

[0013] Specifically, the present invention utilizes the phenomenon of multivalent ion dissolution when the positive electrode material is in a brine environment and the multivalent ions contained in the brine form a hydrogel structure based on dynamic covalent bonds with the added alginate. Since alginate is a linear polymer composed of a mixed arrangement of G monomers and M monomers, the metal ions (such as sodium ions) on the two G units between / inside the molecular chain will be Fe 2+ / Fe 3+ 、Mn 2+ 、Ni 2+Isosubstitution (i.e., the monovalent ions in alginate are replaced by multivalent ions in the subsequent aqueous environment) allows for crosslinking between and within the molecules, which is the basis for alginate to form a hydrogel. Furthermore, the carboxylate groups on the alginate monomers have good hydrophilicity, which helps improve the adaptability of the electrode for electro-deintercalation in aqueous environments. The water storage areas within the resulting hydrogel structure provide good channels for the transport of lithium ions, thereby enabling the electrode to achieve stable lithium ion transport capabilities.

[0014] The following are optional technical solutions of the present disclosure, but are not intended to limit the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0015] As an optional technical solution disclosed in the present invention, based on the mass of the active layer as 100%, the mass of the alginate is 3% to 6%, for example, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8% or 6%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0016] In one embodiment, the alginate includes at least one of sodium alginate, potassium alginate and lithium alginate. For example, a typical but non-limiting combination may be a combination of lithium alginate and potassium alginate, potassium alginate and lithium alginate, or sodium alginate and lithium alginate.

[0017] Too much alginate will make the plate structure denser and hinder the transmission of lithium ions. Too little alginate will have no gel effect and will not be enough to build a gel network.

[0018] In one embodiment, the GM ratio of the alginate is 1:(2-4), for example, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8 or 1:4, etc., and can be selected as 1:3, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0019] In one embodiment, the viscosity of the alginate is 1100-1400 cps, for example, 1100 cps, 1120 cps, 1140 cps, 1160 cps, 1180 cps, 1200 cps, 1220 cps, 1240 cps, 1260 cps, 1280 cps, 1300 cps, 1320 cps, 1340 cps, 1360 cps, 1380 cps, or 1400 cps, but is not limited to the above values. Other values ​​not listed within the above range are also applicable.

[0020] Since the ionic crosslinking of alginate is achieved based on its G units, too many G units in alginate will lead to more ionic crosslinking points, reducing the volume of the gel structure and causing structural collapse. Therefore, a limit is proposed for the GM ratio (the molar ratio of G units to M units) within the alginate molecule; considering that the chain length of the alginate molecule affects the mechanical properties and water storage capacity of the gel, it can generally be indirectly expressed by the viscosity of the aqueous solution. Therefore, a limit is proposed for the viscosity of its aqueous solution, and 1250 cps is further preferred.

[0021] As a preferred technical solution of the present invention, based on the mass of the active layer as 100%, the mass of the positive electrode material after delithiation is 70% to 85%, for example, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84% or 85%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0022] In one embodiment, the active layer further includes a binder and a conductive agent.

[0023] The use of the conductive agent disclosed herein can enhance the lithium ion insertion and extraction capabilities of the positive electrode material. A low proportion of positive electrode material in the plate results in low plate capacity, while a high proportion can easily lead to difficulties in slurry preparation and coating, and insufficient binder and conductive agent can compromise the stability of the positive electrode material.

[0024] The present disclosure does not limit the specific selection of the binder and the conductive agent. For example, the binder can be PVDF, and the conductive agent can be a carbonaceous conductive agent, such as at least one of acetylene black, Ketjen black or Super P. Those skilled in the art can make reasonable adjustments based on actual conditions and needs.

[0025] In one embodiment, based on the mass of the active layer as 100%, the mass of the binder is 7% to 11%, for example, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.4%, 8.6%, 8.8%, 9%, 9.2%, 9.4%, 9.6%, 9.8%, 10%, 10.2%, 10.4%, 10.6%, 10.8% or 11%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0026] In one embodiment, based on the mass of the active layer as 100%, the mass of the conductive agent is 4% to 8%, for example, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8%, 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8% or 8%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0027] As an optional technical solution of the present disclosure, the active layer further includes a conductive skeleton material.

[0028] In one embodiment, the conductive skeleton material comprises chopped carbon fibers.

[0029] In one embodiment, the length of the chopped carbon fiber is 1 to 3 mm, for example, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm or 3 mm, and the width is 0.4 to 0.6 mm, for example, 0.4 mm, 0.42 mm, 0.44 mm, 0.48 mm, 0.5 mm, 0.52 mm, 0.54 mm, 0.56 mm, 0.58 mm or 0.6 mm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0030] The use of conductive skeleton materials, such as chopped carbon fibers, can provide a skeletal structure and form a three-dimensional conductive network when forming the slurry, further enhancing conductivity. This requires limiting the aspect ratio. Chopped carbon fibers offer sufficient mechanical toughness and good electrical conductivity, surpassing multi-walled carbon nanotubes.

[0031] In one embodiment, based on the mass of the active layer as 100%, the mass of the conductive skeleton material is 1% to 5%, for example, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8% or 5%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0032] As an optional technical solution of the present disclosure, the active layer has cracks and pores.

[0033] In a second aspect, the present disclosure provides a method for preparing the lithium extraction and deintercalation plate according to the first aspect, the preparation method comprising:

[0034] mixing the delithiated cathode material with alginate to obtain a modified cathode material;

[0035] The modified positive electrode material is made into a slurry, which is coated on the current collector to form an active layer to obtain a lithium extraction and deintercalation plate.

[0036] As an optional technical solution of the present disclosure, the delithiated positive electrode material is mixed with alginate in an organic solvent.

[0037] The alginate used in the present invention is easily soluble in water but almost insoluble in organic solvents. In order to prevent the alginate from being dissolved during the plate preparation stage, the alginate is first pre-mixed with the lithium-rich positive electrode material after partial delithiation, and then dispersed in an organic solvent (in a hydrophobic environment), and then an active layer is formed and the plate is made, and finally installed and cycled. Although the alginate and the positive electrode material in the active layer of the plate are in a mechanical and physical mixed state, during the period of lithium insertion and delithiation cycle of the plate, the alginate begins to dissolve in water and cross-links with the multivalent metal ions released by the positive electrode material, so that the resulting plate has both good mechanical properties and good hydrophilicity during use.

[0038] As an optional technical solution of the present disclosure, a method for preparing the delithiated positive electrode material includes: chemically delithiating a lithium-rich positive electrode material, and drying it to obtain the delithiated positive electrode material. Chemical delithiation can remove lithium from the positive electrode material to obtain lithium vacancies for subsequent lithium insertion. This process imparts the positive electrode material with the ability to insert and remove lithium.

[0039] In one embodiment, the chemical delithiation comprises oxidizing the lithium-rich positive electrode material using an aqueous sodium persulfate solution with a mass concentration of 10% to 20%, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0040] In one embodiment, the lithium-rich positive electrode material includes at least one of LiFePO4, LiMn2O4 or a ternary material. For example, a typical but non-limiting combination may be a combination of LiFePO4 and LiMn2O4, a combination of LiFePO4 and a ternary material, or a combination of a ternary material and LiMn2O4, etc.; the ternary material includes a nickel-cobalt-manganese ternary material LiNiCoMnO2.

[0041] As an optional technical solution of the present disclosure, the method of mixing the delithiated positive electrode material with alginate includes wet ball milling followed by drying.

[0042] In one embodiment, the liquid used in the wet ball milling comprises ethanol.

[0043] The present disclosure uses a liquid that does not dissolve alginate, such as ethanol, to wet-ball mill the delithiated positive electrode material and alginate, thereby maintaining the particulate form of the alginate. Water will dissolve alginate, and the use of water is not conducive to the mixing of alginate and the positive electrode material during ball milling. The use of a suitable organic solvent for wet ball milling is beneficial to avoiding the failure of alginate due to frictional overheating. The obtained particulate form of alginate can better contact with the positive electrode material particles, and the alginate particles can also fill the cracks in the positive electrode material particles; drying can volatilize the ethanol and free water, preventing the subsequent preparation of the slurry from being affected.

[0044] As an optional technical solution of the present disclosure, a method for preparing the modified positive electrode material into a slurry includes: mixing the modified positive electrode material, a binder, a conductive agent and a solvent.

[0045] In one embodiment, the method of preparing the modified positive electrode material into a slurry further comprises: adding a conductive skeleton material and mixing simultaneously.

[0046] In one embodiment, the amount of the solvent added is 120% to 160% of the mass of the formed active layer, for example, 120%, 122%, 124%, 126%, 128%, 130%, 132%, 134%, 136%, 138%, 140%, 142%, 144%, 146%, 148%, 150%, 152%, 154%, 156%, 158% or 160%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0047] When preparing the positive electrode slurry, maintaining the amount of solvent within the above optional range is conducive to obtaining a slurry with good fluidity and viscosity, which is beneficial to the coating of the slurry on the plate.

[0048] As an optional technical solution of the present disclosure, the method of preparing the modified positive electrode material into a slurry further includes: adding a pore-forming agent and mixing simultaneously, wherein the pore-forming agent is ammonium bicarbonate.

[0049] In one embodiment, the drying temperature after the slurry is applied is greater than the temperature at which the pore-forming agent decomposes to generate gas.

[0050] The present disclosure does not limit the specific method of drying the slurry after coating, and for example, vacuum drying or forced air drying may be selected.

[0051] In one embodiment, the amount of the pore-forming agent added is 9% to 13% of the total mass of the other raw materials excluding the solvent, for example, 9%, 9.2%, 9.4%, 9.6%, 9.8%, 10%, 10.2%, 10.4%, 10.6%, 10.8%, 11%, 11.2%, 11.4%, 11.6%, 11.8%, 12%, 12.2%, 12.4%, 12.6%, 12.8% or 13%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0052] It can be understood that the present invention uses a slurry to form an active layer, which must undergo a heating and drying process after coating. During this process, the solvent will evaporate rapidly, and its evaporation path will create a large number of pore structures. Furthermore, when a pore-forming agent that can decompose under heat to produce gas is added, when the drying temperature is greater than the decomposition temperature of the pore-forming agent, the pore-forming agent will decompose in large quantities to produce gas, which further promotes the formation of the pore structure. The small amount of residual water vapor evaporated by heating will also create a certain amount of pore structure. In addition, the material will shrink in this process, causing cracks, and ultimately obtaining a plate with crack-pore characteristics. In order to balance the generation of pores and material shrinkage to prevent the mechanical properties of the active layer from being severely damaged and causing the collapse of the active layer structure, the pore-forming agent is optionally selected as ammonium bicarbonate with a lower decomposition temperature, and the drying treatment method is forced air drying at 90°C for more than 10 hours. This can make the size, number, and position of the generated cracks and pore structures appropriate, so that the cracks-pores facilitate water infiltration without significantly reducing the mechanical properties of the active layer and the plate. At the same time, because alginate is added in this case, the ion-crosslinked gel structure generated by alginate can further offset the adverse effects of the crack-pore structure on the mechanical properties of the plate during use.

[0053] In a third aspect, the present disclosure provides a use of the lithium extraction and deintercalation plate described in the first aspect, wherein the use includes extracting lithium from a salt lake.

[0054] Compared with the existing technical solutions, the present disclosure has at least the following beneficial effects:

[0055] The present disclosure utilizes alginate and adds it to the active layer to form a lithium extraction and deintercalation plate. When the lithium intercalation and deintercalation cycle is carried out in the electric deintercalation device, the alginate forms a hydrogel structure based on ion crosslinking with a small amount of multivalent metal ions dissolved by the positive electrode material in the water flow environment and the multivalent ions contained in the brine itself. The hydrogel structure is distributed inside the plate and has good water storage capacity. Its three-dimensional water channels expand the mass transfer path of lithium ions, stabilize the transmission capacity of lithium ions, and can compensate for the impact of the reduction in mechanical strength and mechanical properties caused by the process of drying the active layer of the plate, which is conducive to maintaining the mechanical stability of the electric deintercalation plate during long-term use and the stability of the electric deintercalation efficiency. The solution provided by the present disclosure has low energy consumption, does not require high-temperature calcination, can fully utilize the physicochemical properties of each substance, is low cost, and is suitable for large-scale production.

[0056] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0058] FIG1 is an electron microscope image of the material in the electrode plate obtained in Example 1;

[0059] FIG2 is a comparison of the charge specific capacities of the plates obtained in Example 1 and Example 2;

[0060] FIG3 is a comparison of the charge specific capacities of the plates obtained in Example 3, Example 1, and Example 4;

[0061] FIG4 is a comparison chart of the average charge specific capacity of the plates obtained in Examples 5, 6, 1, 7, and 8;

[0062] FIG5 is a graph showing the 20th cycle charge capacity retention rate of the electrode plates obtained in Examples 5, 6, 1, 7, and 8;

[0063] FIG6 is a surface morphology of the electrode plates obtained in Examples 9, 10, 1, 11, and 12;

[0064] FIG7 is a comparison of the charge specific capacities of the plates obtained in Examples 9, 10, 1, 11, and 12;

[0065] FIG8 is a graph showing the 20th cycle charge capacity retention rate of the electrode plates obtained in Examples 9, 10, 1, 11, and 12;

[0066] FIG9 is a comparison chart of the charge specific capacity of the electrode plates obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0067] The technical solution of the present disclosure is further illustrated below through specific implementation methods.

[0068] It should be apparent to those skilled in the art that the embodiments are only intended to help understand the present disclosure and should not be considered as specific limitations of the present disclosure.

[0069] Example 1

[0070] This embodiment provides a lithium extraction and deintercalation plate, which is prepared by the following preparation method:

[0071] S1. Take 14 kg of LiFePO4 powder and perform oxidation treatment in a sodium persulfate environment, wherein the concentration of the sodium persulfate aqueous solution is 10%, to obtain a partially delithiated positive electrode material. Then, the material is dried with air at 90°C, and then mixed with 0.8 kg of sodium alginate powder in a ball mill with a sodium alginate to GM ratio of 1:3. Then, add an appropriate amount of ethanol to moisten the mixture. After ball milling for 1 hour, remove the mixture and place it in a vacuum oven at 90°C for 8 hours to obtain a modified positive electrode material.

[0072] S2. Add 26 kg of NMP as a solvent into a blender, then add the modified cathode material obtained in S1, 1.6 kg of PVDF, 0.6 kg of chopped carbon fibers (length 2 mm, width 0.5 mm), 2 kg of ammonium bicarbonate, 0.5 kg of Ketjen Black, and 0.5 kg of Super P, and continue stirring for 12 h until uniform to obtain a slurry;

[0073] S3. The prepared slurry is coated on a titanium mesh with a coating thickness of 2 mm to obtain an initial electrode plate; the initial electrode plate is placed in a 90° C. forced air oven for 10 h, during which the initial electrode plate is completely dried and a lithium extraction and deintercalation electrode plate with a crack-pore morphology is obtained.

[0074] Example 2

[0075] This embodiment provides a lithium extraction and deintercalation plate. In the method for preparing the lithium extraction and deintercalation plate, in step S1, 14 kg of LiFePO4 powder is replaced with 5 kg of LiMn2O4 powder and 9 kg of LiNiCoMnO2 powder, and the concentration of the sodium persulfate aqueous solution is adjusted from 10% to 20%. Except for the above, other conditions are exactly the same as those in Example 1.

[0076] Example 3

[0077] This embodiment provides a lithium extraction and deintercalation plate. The preparation method of the lithium extraction and deintercalation plate uses lithium alginate to replace sodium alginate in step S1, and keeps the GM ratio unchanged. Except for the above, other conditions are exactly the same as those in Example 1.

[0078] Example 4

[0079] This embodiment provides a lithium extraction and deintercalation plate. The preparation method of the lithium extraction and deintercalation plate uses potassium alginate to replace sodium alginate in step S1, and keeps the GM ratio unchanged. Except for the above, other conditions are exactly the same as those in Example 1.

[0080] Example 5

[0081] This embodiment provides a lithium extraction and deintercalation plate. In the preparation method of the lithium extraction and deintercalation plate, the amount of sodium alginate in step S1 is adjusted from 0.8 kg to 0.5 kg. Except for the above, other conditions are exactly the same as those in Example 1.

[0082] Example 6

[0083] This embodiment provides a lithium extraction and deintercalation plate. In the preparation method of the lithium extraction and deintercalation plate, the amount of sodium alginate in step S1 is adjusted from 0.8 kg to 0.6 kg. Except for the above, other conditions are exactly the same as those in Example 1.

[0084] Example 7

[0085] This embodiment provides a lithium extraction and deintercalation plate. In the preparation method of the lithium extraction and deintercalation plate, the amount of sodium alginate in step S1 is adjusted from 0.8 kg to 1.1 kg. Except for the above, other conditions are exactly the same as those in Example 1.

[0086] Example 8

[0087] This embodiment provides a lithium extraction and deintercalation plate. In the preparation method of the lithium extraction and deintercalation plate, the amount of sodium alginate in step S1 is adjusted from 0.8 kg to 1.2 kg. Except for the above, other conditions are exactly the same as those in Example 1.

[0088] Example 9

[0089] This embodiment provides a lithium extraction and deintercalation plate. In the method for preparing the lithium extraction and deintercalation plate, in step S2, the amount of ammonium bicarbonate is adjusted from 2 kg to 0 kg, that is, no chopped carbon fiber is added. Except for the above, other conditions are exactly the same as those in Example 1.

[0090] Example 10

[0091] This embodiment provides a lithium extraction and deintercalation plate. In the preparation method of the lithium extraction and deintercalation plate, the amount of ammonium bicarbonate in step S2 is adjusted from 2 kg to 1.8 kg. Except for the above, other conditions are exactly the same as those in Example 1.

[0092] Example 11

[0093] This embodiment provides a lithium extraction and deintercalation plate. In the method for preparing the lithium extraction and deintercalation plate, the amount of ammonium bicarbonate is adjusted from 2 kg to 2.2 kg in step S2. Except for the above, other conditions are exactly the same as those in Example 1.

[0094] Example 12

[0095] This embodiment provides a lithium extraction and deintercalation plate. In the method for preparing the lithium extraction and deintercalation plate, the amount of ammonium bicarbonate is adjusted from 2 kg to 2.4 kg in step S2. Except for the above, other conditions are exactly the same as those in Example 1.

[0096] Comparative Example

[0097] This comparative example provides a lithium extraction and deintercalation plate. The preparation method of the lithium extraction and deintercalation plate does not use sodium alginate or other alginates in step S1. Except for the above, other conditions are exactly the same as those in Example 1.

[0098] The lithium extraction and deintercalation plates obtained in the examples and comparative examples were subjected to lithium extraction tests, with a test voltage range of -0.35V to +0.35V and a test current of 0.2C. The test results are shown in Figures 1 to 9.

[0099] Figure 1 shows an electron microscope image of the interior of the plate coating material obtained in Example 1. It can be found that the interior of the material is composed of a large number of particles connected to each other. These particles are obtained by drying the slurry. At the same time, there are a large number of pores between the particles, which objectively provide favorable conditions for the infiltration of brine. In addition, these pores also help to provide lithium ion migration channels. Figure 2 is a comparison of the test results of Example 1 and Example 2, in which the charge specific capacity reflects the ability of the plate to insert and remove lithium ions. From the results, the plate of Example 1 has a lower initial specific capacity, but its capacity retention rate is better, and a slight capacity increase phenomenon occurs. The plate of Example 2 has a higher initial specific capacity. At the same time, as the number of cycles increases, the charge specific capacity fluctuates over a larger range. The specific capacity reaches its highest point at the 15th cycle and then continues to decline. This shows that the plate preparation method provided by the present disclosure is effective for both iron-lithium and ternary materials. In particular, the iron-lithium material shows better stability, and the ternary material has a greater ability to insert and remove lithium.

[0100] Figure 3 is a comparison chart of the results of Examples 3, 1, and 4, in which the modified parameter of Example 3 is lithium alginate, the modified parameter of Example 4 is potassium alginate, and that of Example 1 is sodium alginate. In principle, all three materials have the function of improving the mass transfer capacity of the plate, enhancing the hydrophilicity of the plate, and maintaining mechanical properties. However, due to the differences in the physicochemical properties of lithium, sodium, and potassium ions, their effects on the plate are also different. In comparison, lithium alginate gives the plate a better initial specific capacity, but the plate experiences larger fluctuations in its ability to insert and remove lithium, while potassium alginate makes the plate's insertion and removal of lithium more stable, but also reduces the plate's specific capacity. Overall, sodium alginate achieves a balance between specific capacity and stability.

[0101] Figures 4 and 5 reflect the effect of sodium alginate addition on the lithium extraction performance of the plate. Figure 4 is a comparison of the average charge capacity of the plate in the first 20 cycles. It can be found that the average charge capacity first increases and then decreases with the increase in the amount of sodium alginate added, and reaches a maximum value when the addition amount is 3%. The average charge capacity is the smallest when the addition amount is 6%. This means that a larger addition amount is not conducive to improving the plate capacity. Figure 5 shows the charge capacity retention rate of the plate at the 20th cycle. As can be seen from the figure, the capacity retention rate is best when the addition amount is 4%, while the addition amount of 3% does not have an advantage. Considering that the plate will be in long-term operation, a 4% addition amount is more appropriate.

[0102] Figures 6, 7, and 8 compare the performance of plates with different ammonium bicarbonate additions. Figure 6 shows the surface morphology of the plates after adding 0%, 9%, 10%, 11%, and 12% ammonium bicarbonate. Overall, as the amount of ammonium bicarbonate added increases, more cracks appear on the plate surface, and the types of cracks also become more diverse. When the ammonium bicarbonate content is 0%, 9%, and 10%, the cracks are mainly longitudinal, while when the ammonium bicarbonate content is 11% and 12%, the cracks are more transverse, indicating that the ammonium bicarbonate content affects the crack morphology. Figure 7 shows the charge capacity curves for plates with different ammonium bicarbonate contents (5). It can be seen that plates with 0% and 9% ammonium bicarbonate content initially exhibit lower specific capacities, which tend to stabilize with increasing cycle number. Plates with 11% and 12% ammonium bicarbonate content, while exhibiting high specific capacities in certain cycling intervals, also experience significant capacity fluctuations. This reflects, on the one hand, that the presence of more morphological cracks facilitates lithium ion transport and deintercalation, but also leads to a rapid decrease in specific capacity. This is likely related to blockage of ion transport pathways due to the impurities in the brine used in the experiment. Furthermore, salt precipitation during operation can lead to micropore blockage and other issues, further reducing the specific capacity. Finally, plates with 10% ammonium bicarbonate content achieve a balance between specific capacity and stability, as can be more clearly seen in Figure 8. The plate with 10% ammonium bicarbonate content achieved a capacity retention rate of 98.8% at cycle 20, the best among the ammonium bicarbonate contents examined. In fact, considering that the plates will operate in brine for a long time, plates with 10% ammonium bicarbonate content are suitable.

[0103] Finally, Figure 9 shows the charge capacity results for Example 1 and the comparative plate. It can be seen that, despite a slightly higher initial capacity advantage due to the lack of sodium alginate, the comparative plate experiences rapid capacity decay, with its capacity at cycle 20 being only 66% of that of the plate containing sodium alginate. Therefore, the appropriate addition of sodium alginate during plate production can help improve lithium extraction performance, primarily through cycling stability. Key factors influencing cycling stability are the stability of lithium ion transport and the overall mechanical stability of the plate material.

Claims

1. A lithium extraction and deintercalation plate electrode, comprising a current collector and an active layer disposed on the current collector; the active layer includes a deintercalated cathode material and alginate.

2. The lithium extraction and insertion plate according to claim 1, wherein, Calculated based on the mass of the active layer being 100%, the mass of the alginate is 3% - 6%.

3. The lithium extraction and insertion plate according to claim 1 or 2, wherein, The alginate includes at least one of sodium alginate, potassium alginate, and lithium alginate.

4. The lithium extraction and insertion plate according to any one of claims 1-3, wherein, The GM ratio of the alginate is 1:(2 - 4), and further optionally 1:

3.

5. The lithium extraction and intercalation / deintercalation plate according to any one of claims 1-4, wherein, The viscosity of the alginate is 1100 - 1400 cps.

6. The lithium extraction and intercalation / deintercalation plate according to any one of claims 1-5, wherein, Calculated based on the mass of the active layer being 100%, the mass of the deintercalated cathode material is 70% - 85%.

7. The lithium extraction and intercalation / deintercalation plate according to any one of claims 1-6, wherein, The active layer further includes a binder and a conductive agent.

8. The lithium extraction and insertion plate according to claim 7, wherein, Calculated based on the mass of the active layer being 100%, the mass of the binder is 7% - 11%.

9. The lithium extraction and insertion plate according to claim 7 or 8, wherein Calculated based on the mass of the active layer being 100%, the mass of the conductive agent is 4% - 8%.

10. The lithium extraction and insertion plate according to any one of claims 1-9, wherein, The active layer further includes a conductive skeleton material; Optionally, the conductive skeleton material includes short carbon fibers; Optionally, the length of the short carbon fibers is 1 - 3 mm, and the width is 0.4 - 0.6 mm; Optionally, calculated based on the mass of the active layer being 100%, the mass of the conductive skeleton material is 1％～5％。 11. The lithium extraction and insertion plate according to any one of claims 1-10, wherein, The active layer has cracks and pores.

12. A method for preparing the lithium extraction and deintercalation plate electrode according to any one of claims 1 - 11, comprising: Mixing the deintercalated cathode material with alginate to obtain a modified cathode material; Making the modified cathode material into a slurry, coating it on the current collector to form an active layer, and obtaining the lithium extraction and deintercalation plate electrode.

13. The preparation method of the lithium extraction and insertion plate according to claim 12, wherein, The method for preparing the deintercalated cathode material includes: chemically deintercalating the lithium-rich cathode material and drying to obtain the deintercalated cathode material; Optionally, the chemical deintercalation includes oxidizing the lithium-rich cathode material with an aqueous sodium persulfate solution having a mass concentration of 10% - 20%; Optionally, the lithium-rich cathode material includes at least one of LiFePO4, LiMn2O4, or ternary materials; Optionally, the ternary material includes lithium nickel cobalt manganese oxide LiNiCoMnO2.

14. The preparation method of the lithium extraction and insertion plate according to claim 12 or 13, wherein, The method for mixing the deintercalated cathode material with alginate includes wet ball milling; Optionally, the liquid used in the wet ball milling includes ethanol.

15. The preparation method of the lithium extraction and intercalation / deintercalation plate according to any one of claims 12-14, wherein, The method for making the modified cathode material into a slurry includes: mixing the modified cathode material, binder, conductive agent, and solvent; Optionally, the method for making the modified cathode material into a slurry further includes: adding a conductive skeleton material and mixing simultaneously; Optionally, the addition amount of the solvent is 120% - 160% of the mass of the formed active layer; Optionally, the method for making the modified cathode material into a slurry further includes: adding a pore-forming agent and mixing simultaneously; Optionally, the pore-forming agent is ammonium bicarbonate; Optionally, the drying temperature after coating the slurry is greater than the temperature at which the gas generated by the decomposition of the pore-forming agent is produced; Optionally, the addition amount of the pore-forming agent is 9% - 13% of the total mass of other raw materials except the solvent.

16. Use of the lithium extraction and deintercalation plate electrode according to any one of claims 1 - 11 for extracting lithium from salt lakes.

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