Capacitive deionization filter element and water purification device

Abstract

The present application relates to the technical field of water purification, and provides a capacitive deionization filter element and a water purification device. The capacitive deionization filter element comprises: an electrode assembly, the electrode assembly comprising: an insulating sheet and at least two layers of electrode sheets, the insulating sheet and the electrode sheets being arranged in a stacked manner, and the insulating sheet being interposed between two adjacent layers of electrode sheets; each electrode sheet comprises a current collector layer and adsorption layers, wherein an absorption layer is provided on both a front side and a back side of the current collector layer; two adjacent layers of electrode sheets are respectively configured as a positive electrode sheet and a negative electrode sheet, and a water transport channel for accommodating the insulating sheet is formed between the positive electrode sheet and the negative electrode sheet; the adsorption layers comprise activated carbon, titanium dioxide, a conductive agent, and a binder, and a mass ratio of the activated carbon to the titanium dioxide is (5-1):1. The capacitive deionization filter element of the present application has a relatively simple structure, simplifies the stacking arrangement process for electrode assemblies, facilitates processing and production, reduces processing costs, and also ensures the effectiveness of raw water purification treatment.

Description

Capacitive deionization filter cartridge and water purification device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to the Chinese Patent Application No. 202411278430.X, filed on September 11, 2024, entitled "Capacitive Deionization Filter Cartridge and Water Purification Device", which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of water purification, and in particular to a capacitive deionization filter cartridge and a water purification device. BACKGROUND

[0004] Capacitive deionization (CDI) is a water desalination and purification technology based on the double-layer capacitance theory. The basic principle is that when a low voltage is applied to the electrode, the cations, anions or charged particles in the solution migrate to the two poles under the action of electric field force and concentration gradient, and are adsorbed on the electrode surface to form a double layer, thereby achieving the purpose of desalination or purification. Capacitive deionization technology can achieve different water qualities under different voltages, while retaining ions beneficial to the human body and removing heavy metal ions. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the related art. To this end, the present application proposes a capacitive deionization filter cartridge, which has a relatively simple structure, simplifies the lamination arrangement process of the electrode assembly, is convenient for processing and production, reduces the processing cost, and also ensures the purification treatment effect of raw water.

[0006] The present application also proposes a water purification device.

[0007] The capacitive deionization filter cartridge according to an embodiment of the present application comprises:

[0008] The electrode assembly comprises an insulating sheet and at least two layers of electrode sheets, the insulating sheet and the electrode sheets are arranged in a stack, and the insulating sheet is clamped between two adjacent layers of the electrode sheets.

[0009] The electrode sheet comprises a current collector layer and an adsorption layer, the adsorption layer is arranged on the front and back surfaces of the current collector layer; two adjacent layers of the electrode sheets are respectively configured as positive electrode sheets and negative electrode sheets, and the positive electrode sheets and the negative electrode sheets form a water passage for accommodating the insulating sheet.

[0010] According to an embodiment of the present application, the adsorption layer comprises activated carbon, titanium dioxide, a conductive agent and a binder, and the mass ratio of the activated carbon to the titanium dioxide is (5-1):1.

[0011] According to an embodiment of the present application, the particle size of the activated carbon is 5-15 μm.

[0012] According to an embodiment of the present application, the specific surface area of the activated carbon is 1500-2200 m2 / g.

[0013] According to an embodiment of the present application, the average pore size of the activated carbon is 1-5 nm.

[0014] According to an embodiment of the present application, the particle size of the titanium dioxide is 0.25-1.5 mm.

[0015] According to an embodiment of the present application, the surface area of the titanium dioxide is 200-240 m2 / g.

[0016] According to an embodiment of the present application, the average pore size of the titanium dioxide is 6-9 nm.

[0017] According to an embodiment of the present application, the mass ratio of the conductive agent is 2% to 5% based on the total mass of the adsorption layer; and / or, the mass ratio of the binder is 5% to 10% based on the total mass of the adsorption layer.

[0018] According to an embodiment of the present application, the binder comprises a cellulose-based binder grafted with active groups.

[0019] According to an embodiment of the present application, the cellulose-based binder is sodium carboxymethyl cellulose and / or carboxymethyl cellulose.

[0020] According to an embodiment of the present application, the active groups comprise at least one of sulfonic acid groups, carboxyl groups, and amino groups.

[0021] According to an embodiment of the present application, the capacitive deionization filter element further comprises:

[0022] a center column having a water outlet channel and a water passing hole in communication with the water outlet channel, the water passing hole being arranged on the peripheral wall of the center column;

[0023] the electrode assembly is wound on the peripheral wall of the center column, the electrode assembly is sealed along the two ends of the center column in the axial direction, and the electrode assembly is correspondingly formed into a water outlet end and a water inlet end relative to the inner and outer ends of the center column.

[0024] According to an embodiment of the present application, the water inlet end is in communication with the water outlet end through the water passing hole, the water outlet end extends to the peripheral wall of the center column and forms fluid communication with the water passing hole.

[0025] According to one embodiment of the present application, two adjacent layers of the electrode sheet are oppositely arranged along the stacking direction, and the insulating sheet and the electrode sheet are arranged in a staggered manner along the stacking direction, so that the electrode sheet is hidden between two adjacent layers of the insulating sheet.

[0026] According to one embodiment of the present application, the peripheral wall of the central column is provided with a plurality of groups of water passing holes in the circumferential direction, and each group of water passing holes is arranged along the axial direction of the central column.

[0027] The number of the electrode sheet is greater than two layers, so that the electrode assembly forms a plurality of water passing channels; and the inner end of the electrode assembly forms a plurality of water outlet ends corresponding to the plurality of water passing channels, and the plurality of water outlet ends are oppositely arranged with the plurality of groups of water passing holes.

[0028] According to one embodiment of the present application, the capacitive deionization filter element further comprises:

[0029] A central column, and the electrode assembly is wound on the peripheral wall of the central column.

[0030] The electrode assembly has a water inlet end and a water outlet end, and the water inlet end and the water outlet end are oppositely arranged at two ends of the electrode assembly along the axial direction of the central column, and the water inlet end is communicated with the water outlet end through the water passing channel.

[0031] According to one embodiment of the present application, the electrode assembly further comprises:

[0032] A positive electrode tab, which is electrically connected with the current collector layer of the positive electrode sheet;

[0033] A negative electrode tab, which is electrically connected with the current collector layer of the negative electrode sheet.

[0034] According to one embodiment of the present application, the thickness of the current collector layer is 15-50 μm.

[0035] According to one embodiment of the present application, the thickness of the adsorption layer is 25-200 μm.

[0036] According to one embodiment of the present application, the adsorption layer comprises a first adsorption layer and a second adsorption layer stacked together, and the first adsorption layer is arranged between the current collector layer and the second adsorption layer; the first adsorption layer comprises activated carbon, conductive agent and binder, and the second adsorption layer comprises activated carbon, titanium dioxide, conductive agent and binder.

[0037] And / or, the thickness of the first adsorption layer is 60-95 μm.

[0038] And / or, the total thickness of the first adsorption layer and the second adsorption layer is not greater than 150 μm.

[0039] According to one embodiment of the present application, the adsorption layer comprises a third adsorption layer and a fourth adsorption layer stacked together, the third adsorption layer is arranged between the current collector layer and the fourth adsorption layer; the third adsorption layer comprises activated carbon, conductive agent and binder, and the fourth adsorption layer comprises activated carbon, binder and titanium dioxide;

[0040] And / or, the thickness of the third adsorption layer is 60-95 μm.

[0041] And / or, the total thickness of the third adsorption layer and the fourth adsorption layer is not more than 150 μm.

[0042] According to one embodiment of the present application, the adsorption layer comprises a fifth adsorption layer and a sixth adsorption layer stacked together, the fifth adsorption layer is arranged between the current collector layer and the sixth adsorption layer; the fifth adsorption layer comprises activated carbon, conductive agent and binder, and the sixth adsorption layer comprises conductive agent, binder and titanium dioxide;

[0043] And / or, the thickness of the fifth adsorption layer is 60-95 μm.

[0044] And / or, the total thickness of the fifth adsorption layer and the sixth adsorption layer is not more than 150 μm.

[0045] According to one embodiment of the present application, the capacitive deionization filter element further comprises:

[0046] A housing having a receiving cavity, a water inlet and a water outlet communicating with the receiving cavity;

[0047] The electrode assembly is arranged in the receiving cavity, and is used for purifying raw water input into the receiving cavity through the water inlet, and the purified water after purification is discharged from the water outlet.

[0048] The water purification equipment according to the embodiment of the present application comprises: a machine body and a capacitive deionization filter element as described above; the machine body has a mounting cavity, and the capacitive deionization filter element is detachably arranged in the mounting cavity.

[0049] The one or more technical solutions described above in the embodiments of the present application have at least one of the following technical effects: by arranging the adsorption layer on the front and back surfaces of the current collector layer, the integrated design of the electrode sheet is realized, and the electrode assembly can be formed only by stacking the electrode sheet and the insulating sheet in an alternating arrangement; such stacking and arrangement design of the electrode assembly simplifies the arrangement structure of the electrode assembly, facilitates processing and production, and is conducive to reducing production cost.

[0050] Meanwhile, in practical application, only the adjacent two electrode sheets are electrically connected to the positive and negative poles of the power supply, so that the ions in the raw water passing through the water passage can be adsorbed, and the raw water can be purified.

[0051] Further, by setting the adsorption layer to include activated carbon, titanium dioxide, conductive agent and binder, and configuring the mass ratio of the activated carbon to the titanium dioxide to be (5-1):1, the activated carbon can be used to adsorb the ions in the raw water, and the surface of the titanium dioxide has many functional groups (carboxyl, hydroxyl, etc.) that can react with heavy metal ions to remove the heavy metals in the water through surface complexation. Specifically, in the activated carbon, the heavy metals are mainly removed through pore adsorption, and the surface of the titanium dioxide has many functional groups (carboxyl, hydroxyl, etc.) that can react with heavy metal ions to remove the heavy metals in the water through surface complexation, and the combination of complexation and adsorption can achieve the removal effect. As for other beneficial ions in the raw water, the titanium dioxide cannot remove them, and only the double electric layer and adsorption of the activated carbon can remove them, so that the retention of the beneficial ions can be achieved through the regulation of the electric field. The inventors find that by controlling the mass ratio of the activated carbon to the titanium dioxide to be (5-1):1, this design can not only effectively remove the heavy metals in the water, but also retain the beneficial ions, so as to achieve the purpose of water purification. Therefore, by adding the titanium dioxide to the electrode material and controlling the mass ratio of the activated carbon to the titanium dioxide within the above range, the heavy metal ions in the water can be effectively removed, and the beneficial ions required by the human body can be retained, so as to meet the demand of household water purification.

[0052] Additional aspects and advantages of the application will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the application or the related art, the following will briefly introduce the drawings needed to be used in the embodiments or the related art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, without creative labor, other drawings can also be obtained from these drawings.

[0054] Fig. 1 is a schematic diagram of the cross-sectional structure of the electrode assembly provided by the embodiment of the application;

[0055] Fig. 2 is a schematic diagram of the cross-sectional structure of the electrode sheet provided by the embodiment of the application;

[0056] Fig. 3 is a schematic diagram of the structure of the electrode assembly wound on the outside of the center column according to an embodiment of the application;

[0057] Fig. 4 is a structure schematic diagram of the electrode assembly of the present application wound outside the center column;

[0058] Fig. 5 is a structure schematic diagram of the electrode assembly of the present application wound outside the center column;

[0059] Fig. 6 is a structure schematic diagram of the capacitive deionization filter element of the present application;

[0060] Fig. 7 is a cross-sectional schematic diagram of the capacitive deionization filter element of the present application;

[0061] Fig. 8 is a cross-sectional schematic diagram of the capacitive deionization filter element of the present application;

[0062] Reference signs: 1, electrode assembly; 11, insulating sheet; 12, electrode sheet; 121, current collector layer; 122, adsorption layer; 100, water passage; 101, positive electrode tab; 102, negative electrode tab; 2, center column; 21, water outlet passage; 22, water passage hole; 3, shell; 31, accommodating cavity; 32, water inlet; 33, water outlet; 4, electricity connection assembly; 41, positive electrode terminal; 42, negative electrode terminal. DETAILED DESCRIPTION

[0063] The embodiments of the present application will be further described below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0064] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0065] As shown in Fig. 1 and Fig. 2, the present application provides a capacitive deionization filter element, comprising: an electrode assembly 1; the electrode assembly 1 comprises: an insulating sheet 11 and at least two layers of electrode sheets 12, the insulating sheet 11 and the electrode sheet 12 are arranged in a stack, and the insulating sheet 11 is clamped between the adjacent two layers of electrode sheets 12;

[0066] The electrode sheet 12 comprises a current collector layer 121 and an adsorption layer 122, and the positive and reverse surfaces of the current collector layer 121 are provided with the adsorption layer 122; the adjacent two electrode sheets 12 are configured as positive electrode sheets and negative electrode sheets respectively, and the overwater channel 100 for accommodating the insulating sheet 11 is formed between the positive electrode sheets and the negative electrode sheets.

[0067] The adsorption layer 122 comprises activated carbon, titanium dioxide, a conductive agent and a binder, and the mass ratio of the activated carbon to the titanium dioxide is (5-1):1.

[0068] It can be understood that, according to the actual application requirement, when the electrode assembly 1 is not wound, the insulating sheet 11 and the electrode sheet 12 can be stacked in the stacking direction shown in FIG. 1, so that the capacitive deionization filter element is configured as a square filter element; when the electrode assembly 1 is wound, the insulating sheet 11 and the electrode sheet 12 are stacked in the stacking direction shown in FIG. 1, and then wound until the electrode assembly 1 forms a columnar shape, so that the capacitive deionization filter element is configured as a columnar filter element.

[0069] The insulating sheet 11 and the electrode sheet 12 are stacked in an alternating arrangement to realize that the insulating sheet 11 is clamped between the adjacent two electrode sheets 12. Since the adjacent two electrode sheets 12 are configured as positive electrode sheets and negative electrode sheets respectively, when the number of the electrode sheets 12 is greater than two, in order to meet the water filtration requirement of the electrode assembly 1 on raw water, when the electrode assembly 1 is powered, the positive electrode sheets and the negative electrode sheets can be arranged alternately in the stacking direction, the insulating sheet 11 is clamped between the positive electrode sheets and the negative electrode sheets, and the current collector layer 121 of the positive electrode sheet and the positive electrode of the power supply are electrically connected, and the current collector layer 121 of the negative electrode sheet and the negative electrode of the power supply are electrically connected. When the number of the electrode sheets 12 is equal to two, the insulating sheet 11 can be directly clamped between the positive electrode sheets and the negative electrode sheets.

[0070] For the electrode sheet 12, the current collector layer 121 of the electrode sheet 12 can be made of metal or graphite material, so that the current collector layer 121 is formed as a conductive layer, and the adsorption layer 122 of the electrode sheet 12 can be made of activated carbon and other adsorption materials, so as to realize the adsorption of ions in raw water.

[0071] At the same time, the insulating sheet 11 can be made of plastic material, and the insulating sheet 11 is used to support between the positive electrode sheets and the negative electrode sheets, not only to prevent the positive electrode sheets and the negative electrode sheets from being short-circuited, but also to ensure that the overwater channel 100 is formed between the positive electrode sheets and the negative electrode sheets.

[0072] In practical application, the working of the capacitive deionization filter element includes adsorption purification process and desorption regeneration process. When the adjacent two layers of electrode sheets 12 are electrically connected to the positive and negative poles of the power supply and the power supply is started, the anions and cations in raw water are attracted to the electrode sheets 12 with opposite charges and are adsorbed by the adsorption layer 122 on the electrode sheet 12. The working process of the capacitive deionization filter element is the adsorption purification process.

[0073] Correspondingly, when the power supply is stopped or when a reverse voltage is applied to the adjacent two layers of electrode sheets 12, the ions adsorbed by the adsorption layer 122 are desorbed into the water body of the water passage 100. At this time, the water passage 100 outputs concentrated water containing a higher ion concentration.

[0074] As can be seen from the above, the capacitive deionization filter element shown in the embodiment realizes integrated design of the electrode sheet 12 by arranging the adsorption layer 122 on the front and back surfaces of the current collector layer 121. The electrode sheet 12 and the insulating sheet 11 are arranged in a stacked manner to form the electrode assembly 1. The stacked arrangement of the electrode assembly 1 simplifies the arrangement structure of the electrode assembly 1, facilitates processing and production, and is conducive to reducing production costs.

[0075] At the same time, in practical application, the ions in raw water passing through the water passage 100 can be adsorbed by electrically connecting the adjacent two layers of electrode sheets 12 to the positive and negative poles of the power supply, achieving the purpose of purifying raw water. Since the two sides of the current collector layer 121 of each electrode sheet 12 are provided with the adsorption layer 122, the two sides of each electrode sheet 12 can adsorb ions, thereby ensuring the purification effect of raw water to a certain extent. The capacitive deionization filter element can effectively remove heavy metal ions in water and retain beneficial ions needed by the human body, meeting the demand for household water purification.

[0076] Furthermore, by setting the adsorption layer 122 to include activated carbon, titanium dioxide, a conductive agent, and a binder, and configuring the mass ratio of activated carbon to titanium dioxide to be (5-1):1, the excellent adsorption performance of activated carbon can be utilized to adsorb ions in the raw water. Titanium dioxide has many functional groups (carboxyl groups, hydroxyl groups, etc.) on its surface, which can undergo complexation reactions with heavy metal ions, thus removing heavy metals from the water through surface complexation. Specifically, in activated carbon, heavy metal removal is mainly achieved through pore size adsorption, while the surface of titanium dioxide has many functional groups (carboxyl groups, hydroxyl groups, etc.) that can undergo complexation reactions with heavy metal ions, removing heavy metals from the water through surface complexation. The combined effect of complexation and adsorption achieves the removal effect. However, titanium dioxide cannot remove other beneficial ions in the raw water; they can only be removed through the electric double layer of activated carbon and adsorption. Therefore, the retention of beneficial ions can be achieved through the regulation of the electric field. The inventors discovered that controlling the mass ratio of activated carbon to titanium dioxide to be (5-1):1 not only effectively removes heavy metals from water but also retains beneficial ions, achieving water purification. For example, the mass ratios of activated carbon to titanium dioxide are 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, etc. Therefore, this application, by adding titanium dioxide to the electrode material and controlling the mass ratio of activated carbon to titanium dioxide within the above range, can effectively remove heavy metal ions from water while retaining beneficial ions needed by the human body, meeting the needs of household water purification.

[0077] It should be noted that both the current collector layer 121 and the conductive agent are made of conventional materials in the art, and those skilled in the art can select them according to actual needs. For example, the current collector layer 121 includes, but is not limited to, copper foil, aluminum foil, stainless steel foil, titanium foil, nickel foil, etc. The conductive agent includes, but is not limited to, acetylene black, conductive carbon black, graphite powder, etc. The binder includes, but is not limited to, polyurethane, polyvinylidene fluoride, polystyrene, polyacrylate, polytetrafluoroethylene, etc.

[0078] In some embodiments, heavy metals include, but are not limited to, Pb, As, Fe, Cr, and Cu.

[0079] In some embodiments, the particle size of the activated carbon is 5 μm to 15 μm, and the specific surface area of ​​the activated carbon is 1500 m². 2 / g~2200m 2 / g, the average pore size of activated carbon is 1nm to 5nm. For example, activated carbon particle sizes are 5μm, 7μm, 9μm, 11μm, 13μm, 15μm, etc., and the specific surface area of ​​activated carbon is 1500m². 2 / g, 1600m 2 / g, 1700m 2 / g, 1800m 2 / g, 1900m2 / g, 2000m 2 / g, 2100m 2 / g, 2200m 2 / g, 2300m, etc. The average pore size of the activated carbon is 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, etc. The inventors have found that when the particle size, specific surface area, and average pore size of the activated carbon are controlled within the above ranges, the activated carbon can provide more active sites and has a larger adsorption capacity, thereby having excellent ion adsorption performance and heavy metal removal capability, and the activated carbon can better synergize with the titanium dioxide to remove heavy metal ions and retain a certain amount of beneficial ions.

[0080] In some embodiments, the particle size of the titanium dioxide is 0.25 mm to 1.5 mm, the surface area of the titanium dioxide is 200 m 2 / g to 240 m 2 / g, and the average pore size of the titanium dioxide is 6 nm to 9 nm. For example, the particle size of the titanium dioxide is 0.25 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1.3 mm, 1.5 mm, etc., the surface area of the titanium dioxide is 200 m 2 / g, 210 m 2 / g, 220 m 2 / g, 230 m 2 / g, 240 m 2 / g, etc., and the average pore size of the titanium dioxide is 6 nm, 7 nm, 8 nm, 9 nm, etc. The inventors have found that when the particle size, surface area, and average pore size of the titanium dioxide are controlled within the above ranges, better active functional groups can be provided, and the ion complexing capability is better, thereby improving the removal rate of heavy metals and better synergizing with the activated carbon to retain a certain amount of beneficial ions required by the human body on the basis of removing heavy metals.

[0081] In some embodiments, the mass ratio of the conductive agent based on the total mass of the adsorption layer 122 is 2% to 5%. For example, the mass ratio is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. In this way, the conductive performance of the electrode sheet 12 is improved, and the electron transmission capability of the electrode sheet 12 is improved.

[0082] In some embodiments, the mass ratio of the binder based on the total mass of the adsorption layer 122 is 5% to 10%. For example, the mass ratio is 5%, 6%, 7%, 8%, 9%, 10%, etc. In this way, the contact performance of the materials of the adsorption layer 122 is improved.

[0083] In some embodiments, the binder comprises a cellulose-based binder grafted with active groups, the cellulose-based binder is sodium carboxymethyl cellulose and / or carboxymethyl cellulose, and the active groups comprise at least one of sulfonic acid groups, carboxyl groups, and amino groups. The cellulose-based binder has a large number of hydroxyl groups. On the one hand, during the cyclic charging process, -CH2-OH is easy to be oxidized to form carboxyl groups. The negative electrode material containing carboxyl groups is beneficial to improve the adsorption capacity of cations, inhibit the adsorption of anions, reduce the same ion repulsion, and improve the adsorption capacity. On the other hand, the cellulose-based binder is easy to be grafted with groups such as sulfonic acid groups and amino groups. The grafted binder has anion and cation selectivity, reduces the phenomenon of reduced adsorption capacity caused by the same ion repulsion, and significantly improves the ion adsorption capacity. Therefore, the capacitive deionization filter element has excellent ion adsorption effect and high ion removal rate.

[0084] Further, for the positive electrode sheet, the active groups comprise amino groups; and for the negative electrode sheet, the active groups comprise at least one of sulfonic acid groups and carboxyl groups.

[0085] Further, the mass fraction of the cellulose-based binder is not less than 1% based on the total mass of the adsorption layer 122. For example, the mass fraction of the cellulose-based binder is not less than 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc. By controlling the mass fraction of the cellulose-based binder to be not less than 1%, the binder can have a large number of active groups, thereby ensuring a large ion adsorption capacity and improving the ion adsorption effect and ion removal rate of the electrode.

[0086] Further, the binder further comprises at least one of styrene-butadiene rubber, polytetrafluoroethylene, and polyvinylidene fluoride. By adding the above type of binder, the stability of the adsorption layer 122 in water is improved, and phenomena such as dissolution, peeling, peeling, and cracking of the activated carbon material layer during operation are reduced. According to the embodiments of the present application, the mass fraction of the binder is 2% to 15% based on the total mass of the adsorption layer 122. Preferably, the mass fraction is 3% to 7%. For example, the mass fraction is 2%, 5%, 7%, 10%, 12%, 15%, etc. The inventors have found that by controlling the mass fraction of the binder within the above range, the adhesion performance can be maintained, and the selective groups can be provided for use, and the proportion of active ingredients and conductive agents can be ensured, and the total adsorption capacity can be maintained. In the adsorption layer 122, the mass fraction of the binder is very small compared to the activated carbon material, and therefore, compared to the existing modification of the activated carbon material, the modification of the binder used in the present application can significantly reduce the production cost. From the adsorption performance, the performance of the electrode sheet 12 prepared by the modification of the binder used in the present application is not worse than that of the electrode sheet 12 prepared by the modification of the activated carbon material. Therefore, the present application provides a new idea for improving the adsorption performance of the electrode sheet 12.

[0087] Further, the activated carbon is grafted with the active group, and the active group includes at least one of a sulfonic acid group, a carboxyl group, and an amino group. By grafting the activated carbon material with the active group, the ion adsorption and the ion removal rate of the electrode can be further improved.

[0088] In some embodiments, as shown in FIGS. 3, 4 and 5, the capacitive deionization filter element further includes a center column 2 having a water outlet channel 21 and a water passing hole 22 in communication with the water outlet channel 21, the water passing hole 22 being arranged on the peripheral wall of the center column 2;

[0089] The electrode assembly 1 is wound on the peripheral wall of the center column 2, and the electrode assembly 1 is sealed at both ends along the axial direction of the center column 2, and the inner and outer ends of the electrode assembly 1 relative to the center column 2 correspond to the water outlet end and the water inlet end;

[0090] The water inlet end is in communication with the water outlet end through the water passing channel 100, and the water outlet end extends to the peripheral wall of the center column 2 and forms fluid communication with the water passing hole 22.

[0091] It can be understood that the center column 2 can be configured as a tubular structure, the water outlet channel 21 is formed in the center column 2, one end of the center column 2 is blocked, and the other end is provided with a water flow outlet in communication with the water outlet channel 21. The two ends of the electrode assembly 1 along the axial direction of the center column 2 can be provided with a sealing layer to realize the sealing of the two ends of the electrode assembly 1 along the axial direction of the center column 2, and the material of the sealing layer can be epoxy resin glue.

[0092] In order to ensure the communication effect between the water outlet end of the electrode assembly 1 and the water outlet channel 21, the water passing hole 22 can be arranged in multiple, and the multiple water passing holes 22 can be uniformly arranged on the peripheral wall of the center column 2, and each water passing hole 22 is arranged on the center column 2 in the corresponding winding area of the electrode assembly 1.

[0093] The winding operation of the electrode assembly 1 is as follows: before winding the electrode assembly 1, the insulating sheet 11 and the electrode sheet 12 are stacked in an alternating arrangement along the stacking direction.

[0094] When winding the electrode assembly 1, the inner wall surface close to the water outlet end of the electrode assembly 1 is attached to the peripheral wall of the center column 2, the water outlet end is opposite to a row of water passing holes 22 on the center column 2, and the electrode assembly 1 is wound along the circumferential direction of the center column 2 until the electrode assembly 1 is wound into a cylindrical shape.

[0095] Thus, according to the winding mode of the electrode assembly 1, the water passing channel 100 in the electrode assembly 1 extends along a spiral trajectory, the outer end of the electrode assembly 1 forms a water inlet end, and the inner end of the electrode assembly 1 forms a water outlet end.

[0096] In practical application, when the raw water is purified, the raw water enters the water passage 100 from the water inlet end of the electrode assembly 1, under the action of the electric field between the adjacent two electrode sheets 12, the anions and cations in the raw water are adsorbed by the adsorption layer 122 on the electrode sheet 12, and the deionized purified water flows to the water outlet end of the electrode assembly 1 under the guidance of the water passage 100, then enters the water outlet passage 21 from the water passage hole 22, and finally is output from the water outlet passage 21.

[0097] In some embodiments, the central column 2 also has a water outlet port in communication with the water outlet passage 21, the water outlet port is arranged at the first end of the central column 2, and the water passage hole 22 is arranged on the peripheral wall close to the second end of the central column 2. The water outlet port is configured to be in communication with the water outlet 33 of the capacitive deionization filter element.

[0098] By arranging the water passage hole 22 on the peripheral wall close to the second end of the central column 2, the water passage hole 22 is arranged away from the water outlet port, which can define that the water output from the inner side of the electrode assembly can only gradually converge to the area where the water passage hole 22 is located, and then be output through the water passage hole 22, the water outlet passage 21 and the water outlet port in turn. During the flow of the water, since the water passage hole 22 is arranged away from the water outlet port, the flowing water will gradually converge to the area where the water passage hole 22 is located, which will gradually extrude the bubbles generated in the electrode assembly to the area where the water passage hole 22 is located, then enter the water outlet passage 21 from the water passage hole 22, and be discharged together with the water, thereby effectively removing the bubbles generated in the capacitive deionization filter element.

[0099] During the desalination process of the capacitive deionization filter element, the bubbles generated in the filter element can be effectively discharged, which can prevent the capacitive deionization filter element from generating noise during operation, ensure the stability of the internal electric field of the electrode assembly, and thus ensure the water purification effect of the capacitive deionization filter element.

[0100] In some embodiments, the peripheral wall of the central column 2 is provided with a flow guide groove, and the flow guide groove and the water passage hole 22 form fluid communication.

[0101] It can be understood that by arranging the flow guide groove on the peripheral wall of the central column 2, the gap between the inner side of the electrode assembly and the peripheral wall of the central column 2 can be avoided to be too small to cause flow restriction to the water, thereby facilitating the collection of the purified water output from the inner side of the electrode assembly by the flow guide groove, and then guiding the collected purified water to the water passage hole 22.

[0102] The depth of the flow guide groove can be 2-5 mm.

[0103] In some embodiments, since the length of the central column 2 is substantially the same as the axial length of the electrode assembly along the central axis, the one end of the flow guide groove is arranged on the peripheral wall close to the first end of the central column 2, and the other end is arranged on the peripheral wall close to the second end of the central column 2, so that the flow guide groove can effectively collect the purified water output from the inner side of the electrode assembly at various positions along the axial direction of the central column 2, and ensure the drainage effect of the purified water.

[0104] The flow guide groove can be arranged along a spiral trajectory on the peripheral wall of the central column 2, or arranged along a straight trajectory on the peripheral wall of the central column 2, and the specific arrangement is not limited.

[0105] Preferably, the flow guide groove is arranged along the axial direction of the central column 2, which can effectively reduce the drainage path of the purified water and facilitate the processing of the flow guide groove.

[0106] In some embodiments, in order to ensure the purification effect of the raw water, the two adjacent electrode sheets 12 are arranged opposite to each other along the stacking direction to ensure the coverage of the electric field between the two adjacent electrode sheets 12 as much as possible, and then remove the anions and cations in the raw water based on the electric field between the two adjacent electrode sheets 12.

[0107] Further, the insulating sheet 11 and the electrode sheet 12 are arranged in a staggered manner along the stacking direction, so that the electrode sheet 12 is hidden between the two adjacent insulating sheets 11. This design not only ensures the electrical isolation between the two adjacent electrode sheets 12, but also facilitates the arrangement of the water outlet end of the electrode assembly 1 at a position opposite to the water passing hole 22 on the peripheral wall of the central column 2, so as to ensure that the water passing channel 100 in the electrode assembly 1 and the water outlet channel 21 in the central column 2 are in fluid communication. The stacking direction is along the thickness direction of the insulating sheet 11 or the electrode sheet 12.

[0108] In some embodiments, as shown in FIG. 4, the peripheral wall of the central column 2 is provided with a plurality of groups of water passing holes 22, for example, a plurality of groups of water passing holes 22 are uniformly arranged along the peripheral direction of the central column 2; each group of water passing holes 22 is arranged along the axial direction of the central column 2; the number of electrode sheets 12 is greater than two, so that the electrode assembly 1 forms a plurality of water passing channels 100, and the inner end of the electrode assembly 1 forms a plurality of water outlet ends corresponding to the plurality of water passing channels 100, and the plurality of water outlet ends are arranged opposite to the plurality of groups of water passing holes 22.

[0109] It can be understood that by arranging the number of electrode sheets 12 to be greater than two, the plurality of water passing channels 100 formed by the electrode assembly 1 can be used to purify the raw water flowing through the multiple channels in the capacitive deionization filter element, thereby improving the purification efficiency of the raw water.

[0110] Meanwhile, by setting multiple water outlet ends opposite multiple groups of water passing holes 22, the water passage between each water passing channel 100 and the water outlet channel 21 in the central column 2 can be ensured to be unobstructed, thereby facilitating the water flow rate of the purified water from the capacitive deionization filter core.

[0111] In actual applications, while ensuring the electrical isolation between the adjacent two layers of electrode sheets 12, the end of the electrode assembly 1 close to the central column 2 and the end of the electrode sheet 12 can be sequentially and staggeredly arranged along the extension direction of the electrode sheet 12, and the end of the insulating sheet 11 and the end of the electrode sheet 12 are ensured to be staggered along the extension direction of the electrode sheet 12.

[0112] In some embodiments, the capacitive deionization filter core further comprises a central column 2, and the electrode assembly 1 is wound around the peripheral wall of the central column 2, which can provide support for the electrode assembly 1 wound thereon, thereby ensuring the stability of the entire capacitive deionization filter core.

[0113] Meanwhile, the electrode assembly 1 has a water inlet end and a water outlet end, which are arranged at the two ends of the electrode assembly 1 along the axial direction of the central column 2, and the water inlet end is in communication with the water outlet end through the water passing channel 100.

[0114] In actual applications, after the raw water enters the water passing channel 100 between the adjacent two electrode sheets 12 from the water inlet end, it flows through the water passing channel 100 along the axial direction of the central column 2, and under the action of the electric field between the adjacent two layers of electrode sheets 12, the anions and cations in the raw water are adsorbed by the adsorption layer 122 on the electrode sheet 12, and the purified deionized water flows out from the water outlet end of the electrode assembly 1.

[0115] In some embodiments, as shown in FIGS. 3 and 7, in order to facilitate the connection of the adjacent two electrode sheets 12 to the positive and negative poles of the power supply, the electrode assembly 1 further comprises a positive electrode tab 101 and a negative electrode tab 102, the positive electrode tab 101 is electrically connected to the current collector layer 121 of the positive electrode sheet, and the negative electrode tab 102 is electrically connected to the current collector layer 121 of the negative electrode sheet.

[0116] As shown in FIGS. 4 and 5, one side of each positive electrode sheet current collector layer 121 is provided with a first extension, and one side of each negative electrode sheet current collector layer 121 is provided with a second extension; when the electrode assembly 1 is wound around the peripheral wall of the central column 2, the first extensions of the respective positive electrode sheets are arranged in layers to form the positive electrode tab 101, and the second extensions of the respective negative electrode sheets are arranged in layers to form the negative electrode tab 102.

[0117] In some embodiments, the current collector layer 121 comprises any one of a copper foil, a titanium foil, and a graphite paper, and the current collector layer 121 is configured to be electrically connected to the positive or negative pole of the power supply.

[0118] The adsorption layer 122 is attached to the surface of the current collector layer 121, and the adsorption layer 122 includes an activated carbon layer having excellent adsorption performance and capable of adsorbing ions in raw water.

[0119] In some embodiments, the thickness of the current collector layer 121 of the electrode sheet 12 determines the support strength, winding difficulty, and cost of the electrode sheet 12. If the current collector layer 121 is too thin, the current collector layer 121 is easily damaged, and if the current collector layer 121 is too thick, the cost of the electrode sheet 12 is too high. Therefore, the thickness of the current collector layer 121 is set to 15-50 μm. Optionally, the thickness of the current collector layer 121 is specifically 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0120] At the same time, the thickness of the adsorption layer 122 of the electrode sheet 12 determines the adsorption capacity and adsorption speed. However, if the adsorption layer 122 is too thick, the adsorption layer 122 may crack during winding. Therefore, the thickness of the adsorption layer 122 is set to 25-200 μm. Optionally, the thickness of the adsorption layer 122 is specifically 25 μm, 30 μm, 50 μm, 65 μm, 100 μm, 150 μm, 185 μm, 200 μm, etc.

[0121] In some embodiments, the adsorption layer 122 includes a first adsorption layer and a second adsorption layer stacked together, the first adsorption layer is adjacent to the current collector layer 121, and the first adsorption layer includes activated carbon, a conductive agent, and a binder. The second adsorption layer includes activated carbon, titanium dioxide, a conductive agent, and a binder. In this way, the removal rate of heavy metals in water by the electrode is improved, and beneficial ions required by the human body are retained.

[0122] In some embodiments, the thickness of the first adsorption layer is 60 μm-95 μm, and the total thickness of the first adsorption layer and the second adsorption layer is not greater than 150 μm.

[0123] In some embodiments, the mass percentage of the conductive agent in the adsorption layer 122 is 3%-10%, and the mass percentage of the binder is 5%-15%.

[0124] In some embodiments, the adsorption layer 122 includes a third adsorption layer and a fourth adsorption layer stacked together, the third adsorption layer is adjacent to the current collector layer 121, and the third adsorption layer includes activated carbon, a conductive agent, and a binder. The fourth adsorption layer includes activated carbon, a binder, and titanium dioxide.

[0125] In some embodiments, the thickness of the third adsorption layer is 60 μm-95 μm, and the total thickness of the third adsorption layer and the fourth adsorption layer is not greater than 150 μm. In the fourth adsorption layer, the mass ratio of activated carbon to titanium dioxide is (5-1):1, and the mass percentage of the binder is 10%-15% based on the total mass of the fourth adsorption layer.

[0126] In some embodiments, the adsorption layer 122 comprises a fifth adsorption layer and a sixth adsorption layer stacked together, the fifth adsorption layer is adjacent to the current collector layer 121, the fifth adsorption layer comprises activated carbon, conductive agent and binder, and the sixth adsorption layer comprises conductive agent, binder and titanium dioxide.

[0127] In some embodiments, the thickness of the fifth adsorption layer is 60-95 μm, and the total thickness of the fifth adsorption layer and the sixth adsorption layer is not greater than 150 μm. In the sixth adsorption layer, the mass ratio of the conductive agent to the titanium dioxide is 1:(1-20), and the mass fraction of the binder is 10-15% based on the total mass of the sixth adsorption layer.

[0128] In some embodiments, the insulating sheet 11 can be configured as a porous structure, for example, the insulating sheet 11 comprises insulating woven fabric or insulating mesh. The insulating woven fabric can be woven fabric or melt-blown fabric.

[0129] Although the insulating sheet 11 is arranged in the water passage 100, since the insulating sheet 11 is a porous structure, the insulating sheet 11 does not affect the migration of ions between two adjacent electrode sheets 12, and thus does not affect the adsorption of ions in the water body by the adsorption layer 122 of the electrode sheet 12. On the contrary, the insulating sheet 11 ensures the uniform flow of water in the water passage 100, and can ensure the adsorption effect of the adsorption layer 122 on ions to a certain extent.

[0130] In some embodiments, considering that the greater the thickness of the insulating sheet 11, the smaller the water flow pressure loss and the lower the risk of blockage, but the greater the thickness of the insulating sheet 11, the greater the distance between two adjacent electrode sheets 12, and thus the greater the resistance between two adjacent electrode sheets 12, resulting in poorer water purification performance. Therefore, in order to comprehensively consider the pressure loss and water purification effect, the thickness of the insulating sheet 11 is set to 0.1-1.0 mm; alternatively, the thickness of the insulating sheet 11 is specifically set to 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc.

[0131] In some embodiments, as shown in FIGS. 6, 7 and 8, the capacitive deionization filter element further comprises a housing 3, the housing 3 has a receiving cavity 31, and a water inlet 32 and a water outlet 33 which communicate with the receiving cavity 31;

[0132] The electrode assembly 1 is arranged in the receiving cavity 31, and the electrode assembly 1 is used for purifying raw water input into the receiving cavity 31 through the water inlet 32, and the purified water after purification is discharged from the water outlet 33.

[0133] Specifically, the shell 3 is cylindrical, the electrode assembly 1 is wound on the peripheral wall of the central column 2 and is coaxially arranged with the shell 3; the water inlet 32 and the water outlet 33 can be arranged at the same end of the shell 3, the water outlet 33 is coaxially arranged with the central column 2 and is in communication with the water outlet channel 21 of the central column 2.

[0134] At the same time, the water inlet 32 is arranged on one side of the water outlet 33, after the raw water is input from the water inlet 32 to the containing cavity 31, the raw water is input into the water passing channel 100 through the water inlet end on the side wall of the electrode assembly 1, and is deionized by the positive and negative electrode sheets during the process of flowing through the water passing channel 100, the purified water after the purification treatment passes through the water outlet end of the electrode assembly 1 and the water passing hole 22 on the central column 2 in turn, and then enters the water outlet channel 21, and finally is discharged from the water outlet 33.

[0135] In some embodiments, the capacitive deionization filter element is further provided with an electricity connection assembly 4, the electricity connection assembly 4 includes a positive electrode terminal 41 and a negative electrode terminal 42, at least part of the positive electrode terminal 41 and at least part of the negative electrode terminal 42 are exposed to the shell 3, the positive electrode terminal 41 is electrically connected with the positive electrode tab 101 of the electrode assembly 1, and the negative electrode terminal 42 is electrically connected with the negative electrode tab 102 of the electrode assembly 1. This design facilitates the power supply to apply voltage to the positive and negative electrode sheets through the electricity connection assembly 4.

[0136] The application also provides a method for preparing the electrode sheet, comprising:

[0137] The active carbon, titanium dioxide, conductive agent and binder are mixed in the solvent, and then are applied to the positive and negative surfaces of the current collector layer, and are dried and rolled to obtain the electrode sheet.

[0138] Therefore, the electrode sheet with high heavy metal removal rate and retaining beneficial ions required by human body can be prepared by the above method, and the method is simple, easy to operate, has high electrode sheet production efficiency and low electrode sheet production cost. It should be noted that the features and advantages described above for the electrode sheet also apply to the method, which will not be described here.

[0139] According to the embodiments of the application, the solid content of the mixed solution obtained by mixing the active carbon, titanium dioxide, conductive agent and binder in the solvent is 25% to 35%. It should be noted that the solvent is a superconventional reagent in the art, which can be selected by the person skilled in the art according to the actual situation, for example, the solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and the like.

[0140] According to the embodiments of the application, the temperature of the drying is 70°C to 90°C, and the drying time is 3h to 5h.

[0141] According to the embodiments of the application, the pressure of the rolling is 80T to 100T.

[0142] According to the embodiment of the present application, another method for preparing the electrode sheet comprises: mixing the activated carbon, the conductive agent and the binder in a first solvent, and then applying the mixture on the front and back surfaces of the current collector layer, and then drying and rolling to obtain a first adsorption layer; mixing the activated carbon, the titanium dioxide, the conductive agent and the binder in a second solvent, and then applying the mixture on the side of the first adsorption layer away from the current collector layer, and then drying and rolling to obtain the electrode sheet. Thus, the electrode sheet prepared by the above method comprises the first adsorption layer and the second adsorption layer, the electrode sheet has a high heavy metal removal rate, and retains beneficial ions required by the human body, and the method is simple and easy to implement.

[0143] According to the embodiment of the present application, the solid content of the mixed solution of the activated carbon, the conductive agent and the binder mixed in the first solvent is 25% to 35%. It should be noted that the first solvent and the second solvent are unconventional reagents in the art, and a person skilled in the art can select them according to actual conditions. For example, the first solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc., and the second solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0144] According to the embodiment of the present application, the temperature of the drying is 70°C to 90°C, and the time of the drying is 3h to 5h.

[0145] According to the embodiment of the present application, the pressure of the rolling for preparing the first adsorption layer is 80T to 100T.

[0146] According to the embodiment of the present application, the pressure of the rolling for preparing the second adsorption layer is 55T to 65T.

[0147] According to the embodiment of the present application, another method for preparing the electrode sheet comprises: mixing the activated carbon, the conductive agent and the binder in a third solvent, and then applying the mixture on the front and back surfaces of the current collector layer, and then drying and rolling to obtain a third adsorption layer; mixing the activated carbon, the titanium dioxide and the binder in a fourth solvent, and then applying the mixture on the side of the third adsorption layer away from the current collector layer, and then drying and rolling to obtain the electrode sheet. The third solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc., and the fourth solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0148] According to the embodiment of the present application, another method for preparing the electrode sheet comprises: mixing the activated carbon, the conductive agent, and the binder in a fifth solvent, and then applying the mixture on the positive and negative sides of the current collector layer, and then drying and rolling to obtain a fifth adsorption layer; mixing the conductive agent, titanium dioxide, and the binder in a sixth solvent, and then applying the mixture on the side of the fifth adsorption layer away from the current collector layer, and then drying and rolling to obtain the electrode sheet. The fifth solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc., and the sixth solvent includes but is not limited to N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0149] Based on the electrode sheet prepared by the above method, the capacitive deionization filter element shown in the present application can effectively adsorb and remove heavy metals in raw water, achieve heavy metal purification in water, and retain beneficial ions required by the human body. It should be noted that the features and advantages described above for the electrode sheet also apply to the capacitive deionization filter element, which will not be described here.

[0150] According to the embodiment of the present application, the electrode sheet is a positive electrode sheet or a negative electrode sheet, and preferably, the electrode sheet prepared by the above method is used as a negative electrode sheet.

[0151] If a specific technique or condition is not specified in the examples, it is performed according to the technique or condition described in the literature in the art or according to the product manual. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be purchased through a regular channel.

[0152] Example 1

[0153] (1) Preparation of a negative electrode sheet: the corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder (polyvinylidene fluoride, the binder used in the examples and comparative examples is polyvinylidene fluoride): titanium dioxide = 70:4:6:20, and the powders were mixed, the particle size of the activated carbon was 7 μm, the specific surface area of the activated carbon was 1900 m 2 / g, the average pore size of the activated carbon was 3 nm, the particle size of the titanium dioxide was 0.5 mm, the surface area of the titanium dioxide was 220 m 2 / g, and the average pore size of the titanium dioxide was 7 nm. After mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, which was stirred for 4 h using a stirrer to form a uniform slurry, which was then coated on the current collector layer using a doctor blade coating device, dried at 80°C for 4 h, and then rolled using a rolling machine at 90T to form an electrode sheet with a coating thickness of 85 μm.

[0154] (2) Preparation of positive electrode sheet: the corresponding mass is weighed according to the ratio of activated carbon: conductive carbon black: binder = 88:5:7, and powder mixing is performed, after mixing, the solid powder is added into the solvent to form a 30% solid content solution, after stirring for 4h with a stirrer, a uniform slurry is formed, then it is scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, after rolling with a roller press 90T, an electrode sheet with a coating thickness of 85μm is formed.

[0155] (3) Capacitive deionization filter element: the insulating sheet and the electrode sheet are arranged in an alternating manner to form an electrode assembly, and then the electrode assembly is wound based on a center column, and finally the wound assembly is installed in the shell.

[0156] Example 2

[0157] The difference between Example 2 and Example 1 is:

[0158] (1) Preparation of negative electrode sheet: the corresponding mass is weighed according to the ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:14, and powder mixing is performed, after mixing, the solid powder is added into the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, after stirring for 4h with a stirrer, a uniform slurry is formed, then it is scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, after rolling with a roller press 90T, an electrode sheet with a coating thickness of 85μm is formed.

[0159] Example 3

[0160] The difference between Example 3 and Example 1 is:

[0161] (1) Preparation of negative electrode sheet: the corresponding mass is weighed according to the ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:35, and powder mixing is performed, after mixing, the solid powder is added into the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, after stirring for 4h with a stirrer, a uniform slurry is formed, then it is scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, after rolling with a roller press 90T, an electrode sheet with a coating thickness of 85μm is formed.

[0162] Example 4

[0163] The difference between Example 4 and Example 1 is:

[0164] (1) Preparation of negative electrode sheet: The corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:70, and powder mixing was performed. After mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution. After stirring with a stirrer for 4h, a uniform slurry was formed. Then, it was scraped onto the current collector layer using a scraping device. After drying at 80°C for 4h, the electrode sheet with a coating thickness of 85μm was formed by using a roll press machine with a roll pressure of 90T.

[0165] Example 5

[0166] The difference between Example 5 and Example 1 is:

[0167] (1) Preparation of negative electrode sheet:

[0168] The corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:20, and the mass of each powder weighed was the same as in Example 1. First, 50wt% of the weighed activated carbon, conductive carbon black, and binder were mixed. After mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution. After stirring with a stirrer for 4h, a uniform slurry was formed. Then, it was scraped onto the current collector layer using a scraping device. After drying at 80°C for 4h, the first adsorption layer with a thickness of 85μm was formed on the current collector layer by using a roll press machine with a roll pressure of 90T. Then, the remaining 50wt% of the weighed activated carbon, conductive carbon black, binder, and titanium dioxide were mixed. After mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution. After stirring with a stirrer for 4h, a uniform slurry was formed. Then, it was scraped onto the current collector layer using a scraping device. After drying at 80°C for 4h, the second adsorption layer with a thickness of 50μm was formed on the first adsorption layer by using a roll press machine with a roll pressure of 60T, thereby preparing the electrode sheet.

[0169] Example 6

[0170] The difference between Example 6 and Example 1 is:

[0171] (1) Preparation of negative electrode sheet:

[0172] The corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder = 88:5:7, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, and after stirring with a stirrer for 4h, a uniform slurry was formed, and then it was scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, and after rolling with a roller press 90T, a first adsorption layer with a thickness of 85μm was formed. Subsequently, the corresponding mass of powder was weighed according to the ratio of conductive carbon black: titanium dioxide: binder = 44:44:12, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content slurry, and the slurry was coated on the adsorption layer just prepared, dried at 80°C for 4h, and after rolling with a roller press 60T, an electrode sheet with a total coating thickness of 145μm on one side of the current collector layer was formed.

[0173] Example 7

[0174] The difference between Example 7 and Example 1 is:

[0175] (1) Preparation of negative electrode sheet:

[0176] The corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder = 88:5:7, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, and after stirring with a stirrer for 4h, a uniform slurry was formed, and then it was scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, and after rolling with a roller press 90T, a first adsorption layer with a thickness of 85μm was formed. Subsequently, the corresponding mass of powder was weighed according to the ratio of activated carbon: titanium dioxide: binder = 44:44:12, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content slurry, and the slurry was coated on the adsorption layer just prepared, dried at 80°C for 4h, and after rolling with a roller press 60T, an electrode sheet with a total coating thickness of 145μm on one side of the current collector layer was formed.

[0177] Comparative Example 1

[0178] The difference between Comparative Example 1 and Example 1 is:

[0179] (1) Preparation of negative electrode sheet:

[0180] The corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder = 88:5:7, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, and after stirring with a stirrer for 4h, a uniform slurry was formed, and then it was scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, and after rolling with a roller press 90T, a first adsorption layer with a thickness of 85μm was formed. Subsequently, the corresponding mass of powder was weighed according to the ratio of activated carbon: titanium dioxide: binder = 44:44:12, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content slurry, and the slurry was coated on the adsorption layer just prepared, dried at 80°C for 4h, and after rolling with a roller press 60T, an electrode sheet with a total coating thickness of 145μm on one side of the current collector layer was formed.

[0181] Comparative Example 2

[0182] The difference between Comparative Example 2 and Example 1 is:

[0183] (1) Preparation of the negative electrode sheet: the corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:10, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, and after stirring for 4h with a stirrer, a uniform slurry was formed, and then it was scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, and after rolling with a roller press 90T, an electrode sheet with a coating thickness of 85μm was formed.

[0184] Comparative Example 3

[0185] The difference between Comparative Example 3 and Example 1 is:

[0186] (1) Preparation of the negative electrode sheet: the corresponding mass was weighed according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:80, and powder mixing was performed, and after mixing, the solid powder was added to the solvent N-methyl pyrrolidone to form a 30% solid content mixed solution, and after stirring for 4h with a stirrer, a uniform slurry was formed, and then it was scraped onto the current collector layer using a scraping device, dried at 80°C for 4h, and after rolling with a roller press 90T, an electrode sheet with a coating thickness of 85μm was formed.

[0187] The performance of the capacitive deionization devices prepared in Examples 1-7 and Comparative Examples 1-3 was determined, and the specific method was as follows:

[0188] Heavy metal removal rate (Pb, As, Fe, Cr, Cu): record the initial heavy metal content T1 and the heavy metal ion T2 after flowing through the capacitive deionization module, then the heavy metal removal rate = (1-T2 / T1)*100%.

[0189] Beneficial ion retention rate (Ca, Mg): record the initial beneficial ion content N1 and the beneficial ion content N2 after flowing through the capacitive deionization module, then the beneficial ion retention rate = N2 / N1*100%.

[0190] The test results of the performance of the capacitive deionization filter core prepared in Examples 1-7 and Comparative Examples 1-3 are shown in Table 1 below.

[0191] Table 1: Test results of the performance of the capacitive deionization filter core

[0192] As can be seen from Table 1, the capacitive deionization filter cartridges of Examples 1-7 purify the raw water of heavy metals and retain the beneficial ions required by the human body, and in particular, within the range of activated carbon and titanium dioxide, the effect of the device with a double-layer adsorption layer is better than that of the single-layer device.

[0193] The embodiment of the present application further provides a water purification device, comprising: a machine body and the capacitive deionization filter cartridge as above; the machine body has a mounting cavity, and the capacitive deionization filter cartridge is detachably arranged in the mounting cavity.

[0194] Specifically, the water purification device can be an instant water heater, the machine body can be provided with a mounting port in communication with the mounting cavity, and the capacitive deionization filter cartridge can be inserted and mounted in the mounting cavity through the mounting port.

[0195] Since the water purification device comprises the capacitive deionization filter cartridge, and the specific structure of the capacitive deionization filter cartridge is referred to the above embodiment, the water purification device of the embodiment comprises all the technical solutions of the above embodiments, and thus has at least all the beneficial effects of all the technical solutions of the above embodiments, which will not be described here.

[0196] Finally, it should be noted that the above embodiments are only used to illustrate the present application, but not to limit the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent replacements of the technical solutions of the present application do not deviate from the scope of the present application, and should be covered in the scope of the claims of the present application.

Claims

1. A capacitive deionization filter cartridge, comprising: an electrode assembly, comprising: an insulating sheet and at least two layers of electrode sheets, the insulating sheet and the electrode sheets being arranged in a stack, the insulating sheet being sandwiched between two adjacent layers of the electrode sheets; the electrode sheet comprising a current collector layer and an adsorption layer, the adsorption layer being provided on both sides of the current collector layer; two adjacent layers of the electrode sheets being configured as a positive electrode sheet and a negative electrode sheet respectively, the positive electrode sheet and the negative electrode sheet forming a water passage for accommodating the insulating sheet therebetween; the adsorption layer comprising activated carbon, titanium dioxide, a conductive agent and a binder, the mass ratio of the activated carbon to the titanium dioxide being (5-1) :

1.

2. The capacitive deionization cartridge of claim 1, wherein, the particle size of the activated carbon being 5-15 μm, the specific surface area of the activated carbon being 1500-2200 m2 / g, and the average pore size of the activated carbon being 1-5 nm.

3. The capacitive deionization cartridge of claim 1 or 2, wherein, the particle size of the titanium dioxide being 0.25-1.5 mm, the surface area of the titanium dioxide being 200-240 m2 / g, and the average pore size of the titanium dioxide being 6-9 nm.

4. The capacitive deionization cartridge of any one of claims 1-3, wherein, the mass percentage of the conductive agent based on the total mass of the adsorption layer being 2% to 5%; and / or, the mass percentage of the binder based on the total mass of the adsorption layer being 5% to 10%.

5. The capacitive deionization cartridge of any one of claims 1-4, wherein, the binder comprising an active group grafted cellulose-based binder, the cellulose-based binder being sodium carboxymethyl cellulose and / or carboxymethyl cellulose, and the active group comprising at least one of a sulfonic acid group, a carboxyl group and an amino group.

6. The capacitive deionization cartridge of any one of claims 1 to 5, further comprising: a center column having a water outlet passage and a water passage hole in communication with the water outlet passage, the water passage hole being provided on a peripheral wall of the center column; the electrode assembly being wound on the peripheral wall of the center column, the electrode assembly being sealed at both ends along the axial direction of the center column, and the electrode assembly being correspondingly formed into a water outlet end and a water inlet end relative to the inner and outer ends of the center column; wherein the water inlet end is in communication with the water outlet end through the water passage, and the water outlet end extends to the peripheral wall of the center column and forms fluid communication with the water passage hole.

7. The capacitive deionization cartridge of claim 6, wherein, two adjacent layers of the electrode sheets are oppositely arranged along the stacking direction, and the insulating sheet and the electrode sheets are arranged in a staggered manner along the stacking direction to realize that the electrode sheets are hidden between two adjacent layers of the insulating sheets.

8. The capacitive deionization cartridge of claim 6 or 7, wherein, the peripheral wall of the center column is provided with a plurality of groups of the water passage holes along the circumferential direction, and each group of the water passage holes is arranged along the axial direction of the center column; the number of the electrode sheets is greater than two layers, so that the electrode assembly forms a plurality of water passages; and the inner end of the electrode assembly forms a plurality of water outlet ends corresponding to the plurality of water passages, and the plurality of water outlet ends are oppositely arranged relative to the plurality of groups of the water passage holes.

9. The capacitive deionization filter cartridge according to any one of claims 1 to 8, further comprising: a center column, the electrode assembly being wound on the peripheral wall of the center column; the electrode assembly having a water inlet end and a water outlet end, the water inlet end and the water outlet end being oppositely arranged at both ends of the electrode assembly along the axial direction of the center column, and the water inlet end being in communication with the water outlet end through the water passage.

10. The capacitive deionization cartridge of any one of claims 1 to 9, wherein, the electrode assembly further comprising: a positive electrode tab electrically connected with the current collector layer of the positive electrode sheet; and a negative electrode tab electrically connected with the current collector layer of the negative electrode sheet. ​ 11. The capacitive deionization cartridge of any one of claims 1 to 10, wherein, The thickness of the current collector layer is 15-50 μm, and the thickness of the adsorption layer is 25-200 μm.

12. The capacitive deionization cartridge of any one of claims 1 to 11, wherein, The adsorption layer comprises a first adsorption layer and a second adsorption layer stacked together, and the first adsorption layer is arranged between the current collector layer and the second adsorption layer; the first adsorption layer comprises activated carbon, a conductive agent and a binder, and the second adsorption layer comprises activated carbon, titanium dioxide, a conductive agent and a binder. The thickness of the first adsorption layer is 60-95 μm, and the total thickness of the first adsorption layer and the second adsorption layer is not more than 150 μm.

13. The capacitive deionization cartridge of any one of claims 1 to 12, wherein, The adsorption layer comprises a third adsorption layer and a fourth adsorption layer stacked together, and the third adsorption layer is arranged between the current collector layer and the fourth adsorption layer; the third adsorption layer comprises activated carbon, a conductive agent and a binder, and the fourth adsorption layer comprises activated carbon, a binder and titanium dioxide. The thickness of the third adsorption layer is 60-95 μm, and the total thickness of the third adsorption layer and the fourth adsorption layer is not more than 150 μm.

14. The capacitive deionization cartridge of any one of claims 1 to 13, wherein, The adsorption layer comprises a fifth adsorption layer and a sixth adsorption layer stacked together, and the fifth adsorption layer is arranged between the current collector layer and the sixth adsorption layer; the fifth adsorption layer comprises activated carbon, a conductive agent and a binder, and the sixth adsorption layer comprises a conductive agent, a binder and titanium dioxide. The thickness of the fifth adsorption layer is 60-95 μm, and the total thickness of the fifth adsorption layer and the sixth adsorption layer is not more than 150 μm.

15. The capacitive deionization cartridge of any one of claims 1 to 14, wherein, Further comprising: a housing having a receiving cavity, a water inlet and a water outlet communicating with the receiving cavity; the electrode assembly is arranged in the receiving cavity, and the electrode assembly is used for purifying raw water input into the receiving cavity through the water inlet, and purified water after purification treatment is discharged from the water outlet.

16. A water purification apparatus comprising: a machine body and a capacitive deionization filter element according to any one of claims 1 to 15; the machine body has a mounting cavity, and the capacitive deionization filter element is detachably arranged in the mounting cavity.

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