Ion thermoelectric hydrogel material as well as preparation method and application thereof

Abstract

The invention relates to an ionic thermoelectric hydrogel material as well as a preparation method and application thereof, and belongs to the technical field of hydrogel. The ionic thermoelectric hydrogel material is prepared from a precursor through a curing reaction; wherein based on the total weight of the precursor, the precursor is prepared from the following components in percentage by weight: 5wt%-8wt% of a monomer, 0.5 wt%-2.0 wt% of a reinforcing agent, 0.1 wt%-1.0 wt% of a cross-linking agent, 2wt%-10wt% of inorganic salt, 0.1 wt%-1.0 wt% of an initiator and 80wt%-90wt% of a solvent. The preparation method of the ionic thermoelectric hydrogel material comprises the following steps: dissolving a monomer, a reinforcing agent, a cross-linking agent and inorganic salt in a solvent, uniformly mixing, adding an initiator, uniformly mixing, pouring into a mold, and carrying out a curing reaction to prepare the ionic thermoelectric hydrogel material. The ionic thermoelectric hydrogel material provided by the invention solves the technical problems of poor heat dissipation performance, low strength, low water content and high cost of the existing ionic hydrogel material, can be used for monitoring the working state of a battery cell due to the thermoelectric effect of the ionic thermoelectric hydrogel material, and has wide application prospects in the fields of electric automobiles and energy storage industries.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel technology, specifically relating to an ion thermoelectric hydrogel material, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of new energy vehicles and the energy storage industry, the installed capacity of batteries has also been increasing, with lithium-ion batteries being the most widely used. The performance of battery materials and their internal electrochemical reactions exhibit a strong temperature dependence; a suitable operating temperature is essential to maximize the battery's overall performance. Furthermore, the continuous improvement in battery energy density and charge / discharge rates has brought about more severe thermal safety issues. Violent chemical reactions may occur inside the battery, leading to thermal runaway accidents such as overheating and combustion. When a single battery experiences thermal runaway, it generates a large amount of heat, triggering a chain reaction of thermal runaway in surrounding batteries, compromising the entire battery module and causing significant damage. Currently, the conventional method of placing aerogel or insulating foam between the cells only provides insulation and does not dissipate heat, thus failing to solve the problem of battery thermal runaway.

[0003] Hydrogels are porous materials with high water content. The high heat capacity and latent heat of water provide an effective way for gel materials to store heat and dissipate heat rapidly through evaporation. Furthermore, under thermal diffusion, the temperature difference across the two sides of an ionic thermogel creates a potential difference, converting the temperature signal into a voltage signal. This voltage signal can be integrated into a battery thermal management system to monitor the battery's operating environment status in real time. Therefore, high-water-content ionic thermogel materials hold promise for solving thermal runaway problems and providing a new solution for battery management systems.

[0004] CN116874963A discloses an ionic hydrogel, its preparation method, and its applications. This ionic hydrogel structure contains conventional polymer components as well as an ionic liquid component. The ionic liquid is a phosphorus or nitrogen-containing salt with flame-retardant properties. In the hydrogel system, it exists as freely moving ions, thus exhibiting flame retardancy and ionic thermoelectric effects. It can form an early warning circuit with a millivolt-level voltage alarm to detect potential fire threats as early as possible, and can be applied in high-rise buildings, modern home appliances, and the Internet of Things. However, the water content of this gel material is relatively low (8~40wt%), resulting in limited gel strength. The main component (ionic liquid) is also expensive, limiting its application to conventional fire alarms and lacking good high-temperature heat dissipation properties.

[0005] Therefore, there is an urgent need to research and develop an ion thermoelectric hydrogel material with good high-temperature heat dissipation performance, high strength, high water content and low cost. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an ion thermoelectric hydrogel material, its preparation method and application, so as to solve the technical problems of poor heat dissipation performance, low strength, low water content and high cost of existing ion hydrogel materials.

[0007] To achieve the above objectives, the first aspect of the present invention provides an ion-thermoelectric hydrogel material, which is prepared by a curing reaction of a precursor; wherein, based on the total weight of the precursor, the precursor comprises: 5wt%~8wt% monomer, 0.5wt%~2.0wt% reinforcing agent, 0.1wt%~1.0wt% crosslinking agent, 2wt%~10wt% inorganic salt, 0.1wt%~1.0wt% initiator, and 80wt%~90wt% solvent.

[0008] Preferably, the monomer is selected from one or more of acrylamide, methacrylamide, acrylic acid, and hydroxyethyl methacrylate.

[0009] Preferably, the reinforcing agent is selected from one or more of polyvinyl alcohol, cellulose acetate, carboxymethyl chitosan, sodium alginate, and guar gum.

[0010] Preferably, the crosslinking agent is N,N-methylenebisacrylamide.

[0011] Preferably, the inorganic salt is selected from one or more of calcium chloride, ferric chloride, potassium ferricyanide, and potassium iodate.

[0012] Preferably, the initiator is selected from one or more of potassium persulfate, ammonium persulfate, sodium thiosulfate, and azobisisobutyronitrile.

[0013] Preferably, the solvent is water.

[0014] A second aspect of the present invention provides a method for preparing an ion-thermoelectric hydrogel material as described in the first aspect of the present invention, comprising the following steps: The monomer, reinforcing agent, crosslinking agent and inorganic salt are dissolved in a solvent, mixed well and then an initiator is added. After mixing well, the mixture is poured into a mold for curing reaction to obtain the thermoelectric hydrogel material.

[0015] Preferably, the curing reaction is carried out at room temperature, and the curing reaction time is 2-5 minutes.

[0016] The third aspect of the present invention provides an application of the ion thermoelectric hydrogel material as described in the first aspect of the present invention or the ion thermoelectric hydrogel material prepared by the preparation method as described in the second aspect of the present invention in the electric vehicle and / or energy storage industry.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The ion-thermoelectric hydrogel material provided by this invention has extremely high water content (≥80wt%), high enthalpy, and latent heat, thus serving as an energy storage and heat dissipation medium. When the cell temperature rises, the hydrogel primarily absorbs some heat through heat storage. As the temperature increases, the water in the gel undergoes a phase transition, and the vaporization of the water carries away a significant amount of heat, thereby lowering the cell temperature. The vaporization layer can also prevent heat transfer to adjacent cells, avoiding thermal runaway in the battery cell.

[0018] The ion-thermoelectric hydrogel material provided by this invention exhibits a thermoelectric effect, converting temperature signals into electrical signals, with a Seebeck coefficient of 6-12 mV / K. When the temperature on one side of the gel material increases, the ion carriers within the material gradually migrate from the high temperature to the low temperature under the influence of the temperature gradient, and gradually accumulate at the low temperature. Due to the different interactions between charged ions and the hydrogel framework structure, anions (such as chloride ions) can form hydrogen bonds with ester and amide groups in the polymer structure, thus their migration rate is lower than that of cations (such as calcium ions). Therefore, under the influence of the temperature gradient, anions and cations in the hydrogel material exhibit ion-selective migration, with cations migrating relatively faster and accumulating more at the low temperature end. This creates a potential difference between the high and low temperature ends, and the potential difference has a good linear relationship with the temperature difference. Therefore, sensitive temperature sensing and monitoring of the battery cell's operating status can be achieved by monitoring the potential difference changes of the ion-hydrogel.

[0019] Therefore, the ion-thermoelectric hydrogel material provided by this invention not only possesses excellent high-temperature heat dissipation performance, high strength, and high water content, but also exhibits a thermoelectric effect in the early stage of heat dissipation, directly converting temperature signals into electrical signals. These signals can then be transmitted to the battery thermal management system via wired or wireless means, thus demonstrating broad application prospects in the electric vehicle and energy storage industries. Furthermore, the preparation method of the ion-thermoelectric hydrogel material provided by this invention utilizes readily available raw materials, involves simple process steps, and is low in cost. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of an ion thermoelectric measurement platform is shown. The meanings of the reference numerals in the diagram are as follows: 1-First heat source; 2-Second heat source; 3-Graphite sheet electrode; 4-Thermocouple; 5-Ion thermoelectric hydrogel material; T1-Temperature of the first heat source 1; T2-Temperature of the second heat source 2; V out This is the output voltage (i.e., potential difference). Figure 2 The graph shows the relationship between the temperature difference across the two sides of the ion thermoelectric hydrogel material and the output voltage. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Existing ionic hydrogel materials have low water content (8~40wt%), limited gel strength, high cost of the main component (ionic liquid), and lack good high-temperature heat dissipation properties.

[0024] In view of this, the present invention provides an ion thermoelectric hydrogel material, its preparation method and application, to solve the technical problems of poor heat dissipation performance, low strength, low water content and high cost of existing ion hydrogel materials.

[0025] In a first aspect, embodiments of the present invention provide an ion thermoelectric hydrogel material, which is prepared by a curing reaction of a precursor; wherein, based on the total weight of the precursor, the precursor comprises: 5wt%~8wt% monomer, 0.5wt%~2.0wt% reinforcing agent, 0.1wt%~1.0wt% crosslinking agent, 2wt%~10wt% inorganic salt, 0.1wt%~1.0wt% initiator, and 80wt%~90wt% solvent.

[0026] In some embodiments, the monomer is selected from one or more of acrylamide, methacrylamide, acrylic acid, and hydroxyethyl methacrylate.

[0027] In some embodiments, the reinforcing agent is selected from one or more of polyvinyl alcohol, cellulose acetate, carboxymethyl chitosan, sodium alginate, and guar gum.

[0028] In some embodiments, the crosslinking agent is N,N-methylenebisacrylamide.

[0029] In some embodiments, the inorganic salt is selected from one or more of calcium chloride, ferric chloride, potassium ferricyanide, and potassium iodate.

[0030] In some embodiments, the initiator is selected from one or more of potassium persulfate, ammonium persulfate, sodium thiosulfate, and azobisisobutyronitrile.

[0031] In some embodiments, the solvent is water.

[0032] The ionic thermoelectric hydrogel material provided by this invention is prepared by a curing reaction of a precursor comprising monomers, reinforcing agents, crosslinking agents, inorganic salts, initiators, and solvents. The components contained in the precursor enable the prepared ionic thermoelectric hydrogel material to possess advantages such as high water content and high strength. The high water content of the ionic thermoelectric hydrogel material makes it an excellent medium for energy storage and heat dissipation. When the cell temperature rises, the hydrogel primarily absorbs some heat through heat storage. As the temperature increases, the water in the gel undergoes a phase transition, and the vaporization of the water carries away a significant amount of heat, thereby lowering the cell temperature. The vaporized layer can prevent heat transfer to adjacent cells, avoiding thermal runaway of the battery cell, thus exhibiting excellent heat dissipation performance.

[0033] The ion-thermoelectric hydrogel material provided by this invention exhibits a thermoelectric effect, converting temperature signals into electrical signals, with a Seebeck coefficient of 6-12 mV / K. When the temperature on one side of the gel material increases, the ion carriers within the material gradually migrate from the high temperature to the low temperature under the influence of the temperature gradient, and gradually accumulate at the low temperature. Due to the different interactions between charged ions and the hydrogel framework structure, anions (such as chloride ions) can form hydrogen bonds with ester and amide groups in the polymer structure, thus their migration rate is lower than that of cations (such as calcium ions). Therefore, under the influence of the temperature gradient, anions and cations in the hydrogel material exhibit ion-selective migration, with cations migrating relatively faster and accumulating more at the low temperature end. This creates a potential difference between the high and low temperature ends, and the potential difference has a good linear relationship with the temperature difference. Therefore, sensitive temperature sensing and monitoring of the battery cell's operating status can be achieved by monitoring the potential difference changes of the ion-hydrogel.

[0034] Secondly, embodiments of the present invention also provide a method for preparing an ion-thermoelectric hydrogel material as described in the first aspect of the present invention, comprising the following steps: The monomer, reinforcing agent, crosslinking agent and inorganic salt are dissolved in a solvent, mixed well and then an initiator is added. After mixing well, the mixture is poured into a mold for curing reaction to obtain the thermoelectric hydrogel material.

[0035] In some embodiments, the curing reaction is carried out at room temperature (25°C) for 2 to 5 minutes.

[0036] In some embodiments, the mold can be a mold made of high-strength support material.

[0037] The preparation method of the ion thermoelectric hydrogel material provided by this invention uses readily available raw materials and simple process steps, thus having the advantage of low cost. Meanwhile, the selection of monomers, reinforcing agents, crosslinking agents, inorganic salts, and initiators in the raw materials results in ion thermoelectric hydrogel materials with high strength after curing.

[0038] Thirdly, embodiments of the present invention also provide an application of the ion thermoelectric hydrogel material as described in the first aspect of the present invention or the ion thermoelectric hydrogel material prepared by the preparation method described in the second aspect of the present invention in the electric vehicle and / or energy storage industry.

[0039] The ion thermoelectric hydrogel material provided by this invention has a thermoelectric effect in the early stage of heat dissipation, and can directly convert temperature signals into electrical signals, which can be transmitted to the battery thermal management system via wired or wireless means. Therefore, it has broad application prospects in the fields of electric vehicles and energy storage.

[0040] Example Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available, all instruments and equipment used are conventional instruments and equipment in the art, and all operating methods used are conventional methods in the art.

[0041] Example 1 An ion-thermoelectric hydrogel is prepared by the following steps: Based on the total weight of the precursor, 5 wt% of monomer acrylamide, 1 wt% of reinforcing agent polyvinyl alcohol, 1 wt% of crosslinking agent N,N-methylenebisacrylamide and 2 wt% of inorganic salt calcium chloride were dissolved in 90 wt% solvent water. After mixing, 1 wt% of initiator potassium persulfate was added and mixed. The mixture was then quickly poured into a high-strength support material mold and cured at room temperature for 5 min to obtain the ion thermoelectric hydrogel material.

[0042] Example 2 An ion-thermoelectric hydrogel is prepared by the following steps: Based on the total weight of the precursor, 5 wt% of monomer methacrylamide, 0.5 wt% of reinforcing agent cellulose acetate, 1 wt% of crosslinking agent N,N-methylenebisacrylamide and 5 wt% of inorganic salt ferric chloride were dissolved in 88 wt% solvent water. After mixing, 0.5 wt% of initiator ammonium persulfate was added and mixed. The mixture was then quickly poured into a high-strength support material mold and cured at room temperature for 5 min to obtain the ion thermoelectric hydrogel material.

[0043] Example 3 An ion-thermoelectric hydrogel is prepared by the following steps: Based on the total weight of the precursor, 6 wt% of acrylic acid monomer, 2 wt% of carboxymethyl chitosan reinforcing agent, 0.5 wt% of N,N-methylenebisacrylamide crosslinking agent, and 5 wt% of potassium ferricyanide inorganic salt were dissolved in 86 wt% of water solvent. After mixing, 0.5 wt% of sodium thiosulfate initiator was added and mixed. The mixture was then quickly poured into a high-strength support material mold and cured at room temperature for 5 minutes to obtain the ion thermoelectric hydrogel material.

[0044] Example 4 An ion-thermoelectric hydrogel is prepared by the following steps: Based on the total weight of the precursor, 7 wt% of hydroxyethyl methacrylate monomer, 1 wt% of sodium alginate reinforcing agent, 1 wt% of N,N-methylenebisacrylamide crosslinking agent, and 5 wt% of potassium iodate inorganic salt were dissolved in 85 wt% of water solvent. After mixing, 1 wt% of azobisisobutyronitrile initiator was added and mixed. The mixture was then quickly poured into a high-strength support material mold and cured at room temperature for 5 min to obtain the ion thermoelectric hydrogel material.

[0045] Example 5 An ion-thermoelectric hydrogel is prepared by the following steps: Based on the total weight of the precursor, 7 wt% of monomer methacrylamide, 0.5 wt% of reinforcing agent sodium alginate, 0.2 wt% of crosslinking agent N,N-methylenebisacrylamide, and 10 wt% of inorganic salt calcium chloride were dissolved in 82 wt% solvent water. After mixing, 0.3 wt% of initiator potassium persulfate was added and mixed. The mixture was then quickly poured into a high-strength support material mold and cured at room temperature for 5 minutes to obtain the ion thermoelectric hydrogel material.

[0046] Example 6 An ion-thermoelectric hydrogel is prepared by the following steps: Based on the total weight of the precursor, 8 wt% of monomer methacrylamide, 2 wt% of reinforcing agent guar gum, 1 wt% of crosslinking agent N,N-methylenebisacrylamide and 8 wt% of inorganic salt calcium chloride were dissolved in 80 wt% solvent water. After mixing, 1 wt% of initiator potassium persulfate was added and mixed. The mixture was then quickly poured into a high-strength support material mold and cured at room temperature for 5 min to obtain the ion thermoelectric hydrogel material.

[0047] Taking the ion thermoelectric hydrogel material obtained in Example 1 as an example, an ion thermoelectric measurement platform was built to test the ion thermoelectric potential of the ion thermoelectric hydrogel material.

[0048] like Figure 1 As shown, the ion thermoelectric measurement platform includes a first heat source 1, a second heat source 2, two graphite sheet electrodes 3, two thermocouples 4, an ion thermoelectric hydrogel material 5, and a digital multimeter (not shown). The first heat source 1 and the second heat source 2 are respectively located on the upper and lower sides of the ion thermoelectric hydrogel material 5. The two graphite sheet electrodes 3 are respectively attached to the upper and lower ends of the ion thermoelectric hydrogel material 5. The two thermocouples 4 are respectively attached to the surfaces of each heat source in contact with the ion thermoelectric hydrogel material 5. The two thermocouples 4 measure the temperature T1 of the corresponding first heat source 1 and the temperature T2 of the corresponding second heat source. The two graphite sheet electrodes 3 are connected to the digital multimeter via leads to measure the output voltage (i.e., the ion thermoelectric potential) V.out .

[0049] The principle of testing the ionic thermoelectric potential of ionic thermoelectric hydrogel materials is: constructing a structure such as... Figure 1 The ion thermoelectric measurement platform shown has a 0.1 mm gap between the two graphite sheet electrodes 3. A DC power supply is used to heat the first heat source 1 (specifically, a serpentine heating element) to create a temperature difference across the ion thermoelectric hydrogel material 5. The temperatures on both sides are recorded in real time by two thermocouples 4. Due to the Thaler effect, a potential difference appears across the ion thermoelectric hydrogel material 5, which is measured using a digital multimeter. out The sample size of the ion-thermoelectric hydrogel material 5 is 120mm*60mm*1mm. Based on the temperature difference and output voltage of the two thermocouples 4, the following diagram is plotted: Figure 2 The diagram shown is a relational diagram. From... Figure 2 As can be seen, the ion thermoelectric hydrogel of Example 1 can generate different output voltages with changes in temperature difference, and there is a good linear relationship between the output voltage and the temperature difference, with a correlation coefficient R. 2 It has a high value of 0.9821 and good repeatability.

[0050] In summary, the ion thermoelectric hydrogel material provided by this invention has an extremely high water content (≥80wt%), which can utilize the phase change of water in the gel to remove heat, thereby reducing the temperature of the battery cell and preventing thermal runaway. Simultaneously, the ion thermoelectric hydrogel material provided by this invention also exhibits a thermoelectric effect, converting temperature signals into electrical signals. Therefore, the electrical signals can be transmitted to the battery thermal management system via wired or wireless means. That is, by monitoring the potential difference changes of the ion thermoelectric hydrogel, sensitive temperature sensing and monitoring of the battery cell's operating status can be achieved, thus showing broad application prospects in the electric vehicle and energy storage industries. Furthermore, the preparation method of the ion thermoelectric hydrogel material provided by this invention uses readily available raw materials, has simple process steps, and low cost. At the same time, the selection of monomers, reinforcing agents, crosslinking agents, inorganic salts, and initiators in the raw materials results in a high-strength ion thermoelectric hydrogel material after curing.

[0051] Therefore, the ion thermoelectric hydrogel provided by the present invention effectively solves the technical problems of poor heat dissipation performance, low strength, low water content and high cost of existing ion hydrogel materials.

[0052] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0053] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0054] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An ion-thermoelectric hydrogel material, characterized in that, It is prepared by curing a precursor; wherein, based on the total weight of the precursor, the precursor comprises: 5wt%~8wt% monomer, 0.5wt%~2.0wt% reinforcing agent, 0.1wt%~1.0wt% crosslinking agent, 2wt%~10wt% inorganic salt, 0.1wt%~1.0wt% initiator and 80wt%~90wt% solvent.

2. The ion thermoelectric hydrogel material according to claim 1, characterized in that, The monomer is selected from one or more of acrylamide, methacrylamide, acrylic acid, and hydroxyethyl methacrylate.

3. The ion thermoelectric hydrogel material according to claim 1, characterized in that, The reinforcing agent is selected from one or more of polyvinyl alcohol, cellulose acetate, carboxymethyl chitosan, sodium alginate, and guar gum.

4. The ion thermoelectric hydrogel material according to claim 1, characterized in that, The crosslinking agent is N,N-methylenebisacrylamide.

5. The ion thermoelectric hydrogel material according to claim 1, characterized in that, The inorganic salt is selected from one or more of calcium chloride, ferric chloride, potassium ferricyanide, and potassium iodate.

6. The ion thermoelectric hydrogel material according to claim 1, characterized in that, The initiator is selected from one or more of potassium persulfate, ammonium persulfate, sodium thiosulfate, and azobisisobutyronitrile.

7. The ion thermoelectric hydrogel material according to claim 1, characterized in that, The solvent is water.

8. A method for preparing an ion-thermoelectric hydrogel material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The monomer, reinforcing agent, crosslinking agent and inorganic salt are dissolved in a solvent, mixed well and then an initiator is added. After mixing well, the mixture is poured into a mold for curing reaction to obtain the thermoelectric hydrogel material.

9. The method for preparing the ion thermoelectric hydrogel material according to claim 8, characterized in that, The curing reaction is carried out at room temperature for 2-5 minutes.

10. The application of an ion thermoelectric hydrogel material as described in any one of claims 1 to 7, or an ion thermoelectric hydrogel material prepared by the preparation method as described in claim 8 or 9, in the electric vehicle and / or energy storage industry.

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