Hydride ion conductors, methods for producing the same, and applications

Abstract

This application provides a hydride ion conductor comprising a rare earth metal binary hydride, the chemical formula of which is REH x In this formula, RE represents a rare earth metal, and the range of x is 1 to 10. In this application, rare earth metal binary hydrides or mixtures mainly composed of rare earth metal binary hydrides are used for the first time as hydride ion conductors, expanding the scope of research on solid electrolyte systems. The hydride ion conductors developed by this method exhibit excellent electrical conductivity not only at room temperature but also at low temperatures, and the assembled all-solid-state hydride ion battery can operate at room temperature.

Description

[Technical Field]

[0001] This application relates to hydride ion conductors, methods for producing the same, and applications, and belongs to the field of materials technology. [Background technology]

[0002] Li + kaNa + H + , O 2- Various ionic conductors capable of conducting ions such as H are already widely used in fields such as secondary batteries, fuel cells, electrochemical reactions, separation membranes, and sensors. - TiN₂ has a maximum redox potential of -2.3V, and hydride ion conductors can be used to construct new types of hydride ion batteries and fuel cells, and may also be used as electrolytes for electrochemical reduction reactions of small molecules (e.g., CO₂, N₂, etc.). Several hydride ion conductors have already been reported, mainly of two types: one is alkaline earth metal-based, such as binary hydrides, oxyhydrides, and halogen hydrides, and the other is rare earth metal-based, mainly oxyhydrides. Research systems on hydride ion conductors are still few, and most systems have low ionic conductivity at medium- and low temperatures and room temperature, so applications in the field of electrochemistry are still untapped. Achieving high hydride ion conductivity and high ion transportability at room temperature remains very difficult. x Thin films can separate hydrogen through mixed conduction of hydride ions and electrons, and have been reported to exhibit superior hydrogen permeability compared to noble metal Pd films, making them promising for applications in hydrogen purification and membrane reactors.

[0003] Rare-earth metal hydrides have been widely studied and applied in fields such as photochromic glasses, hydrogen storage materials, and superconducting materials. Binary rare-earth metal hydrides typically have a face-centered cubic structure, with the rare-earth metals occupying face-center and vertex positions, forming gaps between multiple tetrahedra and octahedra. Hydrogen preferentially occupies the tetrahedral gaps first, followed by the octahedral gaps. If the amount of hydrogen is insufficient or the synthesis conditions differ, tetrahedral and octahedral vacancies may form. Furthermore, tetrahedral and octahedral H atoms are in the nearest neighbor positions, and these characteristics provide a favorable environment for hydrogen movement. In fact, the rapid diffusion of hydrogen in rare-earth hydrides was discovered as early as the 1990s and was studied as a method for producing photochromic glasses. However, to date, there are no reports of direct research on rare-earth metal binary hydrides as hydride ion conductors, and this field remains largely unexplored. Nevertheless, this invention demonstrates that using rare-earth metal binary hydrides as hydride ion conductors is reliably feasible and that they exhibit excellent performance at both room temperature and low temperatures. This invention will significantly broaden the research framework and application range of solid electrolyte materials. [Overview of the project]

[0004] This invention provides a method for synthesizing novel hydride ion conductors and research on their applications. Specifically, it involves reacting rare earth metal elements or rare earth metal compounds with hydrogen as precursors to synthesize rare earth metal binary hydrides or hydride ion conductors mainly composed of rare earth metal binary hydrides, and then studying the performance and applications of these hydride ion conductors.

[0005] A hydride ion conductor is provided, which contains a rare earth metal binary hydride, the chemical formula of which is REH x And, In the formula, RE represents rare earth metals, and the range of x is 1 to 10.

[0006] Optionally, the rare earth metal RE includes at least one of the following: scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0007] Optionally, the mass fraction of rare-earth metal binary hydrides in hydride ion conductors is 50-100%.

[0008] The above method for producing the hydride ion conductor is as follows: The method includes the steps of reacting a rare earth metal source with hydrogen to form a reaction product containing a rare earth metal binary hydride, and processing the reaction product to form a hydride ion conductor.

[0009] Optionally, the rare earth metal source includes at least one of the following: rare earth metal elements, rare earth metal alloys, rare earth metal hydrides, rare earth metal nitrides, rare earth metal halides, rare earth metal oxides, rare earth metal sulfides, rare earth metal carbonylates, and rare earth metal carbides.

[0010] Optionally, a method for processing the reaction product to form a hydride ion conductor involves grinding the reaction product into a powder, and then extruding the powder to form a hydride ion conductor.

[0011] Optionally, the above method further includes attaching electrodes to both ends of an extruded hydride ion conductor.

[0012] Optionally, a method for reacting a rare earth metal source with hydrogen includes at least one of mechanical ball mill grinding, closed-system hydrogenation, and fluid-system hydrogenation.

[0013] Optionally, the conditions for mechanical ball mill grinding are: rotation speed of 50 to 500 revolutions per minute, ball mass ratio of 1:1 to 100:1, H2 partial pressure in the ball mill grinding atmosphere of 0.1 to 100 bar, and ball mill grinding time of 0.1 to 60 hours.

[0014] Optionally, the above closed-system hydrogenation conditions are a temperature of -100 to 900°C, an H2 partial pressure of 0.1 to 200 bar, and a reaction time of 0.1 to 60 hours.

[0015] Optionally, the above fluidized system hydrogenation conditions are: temperature 20-900°C, H2 partial pressure 0.1-50 bar, H2 flow rate 10-300 mL / min, and reaction time 0.1-60 hours.

[0016] The present invention also provides applications of the above-mentioned hydride ion conductor in the construction of novel secondary batteries, fuel cells, electrochemical reactors, hydrogen separation membranes, sensors, and membrane reactors.

[0017] Pure hydride ion conductors in rare-earth metal binary hydrides are used in the construction of new secondary batteries, fuel cells, and electrochemical reactors. Mixed hydride ion and electron conductors are used in hydrogen separation membranes, sensors, and membrane reactors.

[0018] The present invention offers the following advantages. This application is the first to use a rare-earth metal binary hydride or a mixture mainly composed of a rare-earth metal binary hydride as a hydride ion conductor, thereby expanding the scope of research on solid electrolyte systems. The hydride ion conductor developed by this method exhibits excellent electrical conductivity not only at room temperature but also at low temperatures, and the assembled all-solid-state hydride ion battery can operate at room temperature. [Brief explanation of the drawing]

[0019] [Figure 1] This curve shows the temperature-dependent change in the hydride ion conductivity of LaH3 synthesized using this method. [Figure 2] This figure shows the discharge curve of the all-solid-state battery Ti / LaH3 / TiH2 synthesized using this method. [Figure 3] It is a curve showing the change of the hydride ion conductivity of CeH3 synthesized by this method with temperature. [Figure 4] It is a curve showing the change of the hydride ion conductivity of PrH3 synthesized by this method with temperature.

Embodiments for Carrying out the Invention

[0020] To further illustrate the present invention, the following specific examples are given, but these do not limit the present invention.

[0021] Unless otherwise specified, all raw materials in the examples of this application are commercially purchased. The equipment used in this application is a BioLogic VSP-300 electrochemical workstation. In the present invention, a rare earth metal element or a rare earth metal compound is used as a precursor to react with hydrogen to synthesize a hydride ion conductor mainly composed of a rare earth metal binary hydride or a rare earth metal binary hydride, and the performance and application of the hydride ion conductor are studied.

[0022] Example 1: Preparation of LaH3 and Research on Its Performance and Application Step 1: Weigh 10 g of metallic La in a glove box, put it into a reactor, fill the reactor with 50 bar of H2, heat it to 500 °C at 10 °C / min in a closed system, and maintain it at 500 °C for 2 hours.

[0023] Step 2: Grind 400 mg of the reaction product in Step 1 into a uniform powder in a mortar, and compress the powder at a pressure of 100 MPa using a hydraulic press to form a sheet with a diameter of 10 mm and a thickness of about 1 mm.

[0024] Step 3: The sheet obtained in Step 2 was attached to a stainless-steel battery buckle. In order to increase the contact area and reduce the contact resistance, nickel foam was used as an electrode on both sides of the sheet. Then, using an electrochemical workstation, the impedance spectrum and DC polarization curve of the battery buckle were measured. The measurement temperature was set from -40°C to 20°C, with one point measured every 10°C. After maintaining each temperature point constant for 2 hours, the next measurement was taken. The curve showing the change in the hydride ion conductivity of LaH3 with temperature is shown in Figure 1. As can be seen from Figure 1, the hydride ion conductivity of LaH3 at room temperature (20°C) reaches 10 -3 S cm -1 , which reaches the world's highest level among current hydride ion conductors.

[0025] Assembly of the all-solid-state battery Ti / LaH3 / TiH2. Ti, LaH3, and TiH2 were compressed at a pressure of 100 MPa into sheets with a diameter of 10 mm and a thickness of about 1 mm respectively. They were stacked and assembled in a stainless-steel battery buckle. In order to increase the contact area and reduce the contact resistance, one sheet of nickel foam was added to the upper and lower ends respectively. Then, using an electrochemical workstation, the constant-current discharge curve of the battery buckle was measured. The temperature was kept constant at 30°C, and the current was kept constant at -500 nA. The voltage change curve with the passage of time was collected. The discharge curve of the all-solid-state battery Ti / LaH3 / TiH2 is shown in Figure 2. As can be seen from Figure 2, the all-solid-state hydride battery has been successfully discharged, which not only proves that LaH3 is an excellent room-temperature hydride ion conductor but also proves the feasibility of this new hydride secondary battery.

[0026] Example 2: Preparation of CeH3 and Study of Its Performance Step 1: Weighed 5 g of metallic Ce in a glove box, put it into a ball-mill tank, filled the ball-mill tank with 20 bar of H2, and milled it at a rotation speed of 300 rpm for 10 hours, stopping for 2 minutes every 10 minutes of operation and rotating it in the opposite direction.

[0027] Step 2: Take 400 mg of the ball milling product from Step 1 and compress the powder at a pressure of 100 MPa using a hydraulic press to form a sheet with a diameter of 10 mm and a thickness of approximately 1 mm.

[0028] Step 3: The sheet obtained in Step 2 was mounted on a stainless steel battery buckle. Nickel foam was used as electrodes on both sides of the sheet to increase the contact area and reduce contact resistance. An electrochemical workstation was then used to measure the impedance spectrum and DC polarization curve of the battery buckle. The measurement temperature was set from -40°C to 20°C, with one measurement taken at every 10°C interval, and each temperature point was kept constant for 2 hours before the next measurement. Figure 3 shows the curve illustrating the temperature dependence of the hydride ion conductivity of CeH3.

[0029] Example 3: Preparation of PrH3 and study of its performance Step 1: Weigh 35g of Pr2O in a glove box, place it in a flow reactor, introduce fluid H2 at a flow rate of 100mL / min and a pressure of 10bar, heat the mixture at a rate of 10°C / min to 500°C, and maintain the temperature at 500°C for 12 hours.

[0030] Step 2: Take 400 mg of the reaction product from Step 1, and compress the powder using a hydraulic press at a pressure of 100 MPa to form a sheet with a diameter of 10 mm and a thickness of approximately 1 mm.

[0031] Step 3: The sheet obtained in Step 2 was mounted on a stainless steel battery buckle. Nickel foam was used as electrodes on both sides of the sheet to increase the contact area and reduce contact resistance. An electrochemical workstation was then used to measure the impedance spectrum and DC polarization curve of the battery buckle. The measurement temperature was set from -40°C to 20°C, with one measurement taken at every 10°C interval, and each temperature point was kept constant for 2 hours before the next measurement. Figure 4 shows the curve illustrating the temperature dependence of the hydride ion conductivity of PrH3.

[0032] Example 4: Preparation of NdH3 and study of its performance Step 1: Weigh 35g of Nd2S in a glove box, place it in a flow reactor, introduce fluid H2 at a flow rate of 50mL / min and a pressure of 5bar, heat the mixture at a rate of 10°C / min to 300°C, and maintain the temperature at 300°C for 12 hours.

[0033] Step 2: 400 mg of the reaction product from Step 1 was ground in a mortar until it became a uniform powder, and the powder was compressed using a hydraulic press at a pressure of 100 MPa to form a sheet with a diameter of 10 mm and a thickness of approximately 1 mm.

[0034] Step 3: The sheet obtained in Step 2 was mounted on a stainless steel battery buckle. Nickel foam was used as electrodes on both sides of the sheet to increase the contact area and reduce contact resistance. An electrochemical workstation was then used to measure the impedance spectrum and DC polarization curve of the battery buckle. The measurement temperature was set from -40°C to 20°C, with one measurement taken at every 10°C interval, and each temperature point was kept constant for 2 hours before the next measurement.

[0035] The foregoing are merely some embodiments of this application and are not intended to limit this application in any form. While this application is disclosed as described above in preferred embodiments, these are not intended to limit it. Those skilled in the art will find that making some modifications or changes to the technical content disclosed above, without departing from the scope of the technical solutions of this application, is equivalent to equivalent embodiments and falls within the scope of the technical solutions.

Claims

1. A hydride ion conductor comprising a rare earth metal binary hydride, wherein the chemical formula of the rare earth metal binary hydride is REH ｘ And, A hydride ion conductor characterized in that, in the formula, RE represents a rare earth metal and the range of x is 1 to 10.

2. The hydride ion conductor according to claim 1, characterized in that the rare earth metal RE includes at least one of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

3. The hydride ion conductor according to claim 1, characterized in that the mass fraction of rare earth metal binary hydrides in the hydride ion conductor is 50 to 100%.

4. A method for producing a hydride ion conductor according to claims 1 to 3, A manufacturing method characterized by comprising the steps of reacting a rare earth metal source with hydrogen to form a reaction product containing a rare earth metal binary hydride, and processing the reaction product to form a hydride ion conductor.

5. The method according to 4, characterized in that the rare earth metal source includes at least one of rare earth metal elements, rare earth metal alloys, rare earth metal hydrides, rare earth metal nitrides, rare earth metal halides, rare earth metal oxides, rare earth metal sulfides, rare earth metal carbonylates, and rare earth metal carbides.

6. The method according to claim 4, characterized in that the method for processing the reaction product to form a hydride ion conductor involves grinding the reaction product into a powder, and then extruding the powder to form a hydride ion conductor.

7. The method according to 6, further comprising attaching electrodes to both ends of an extruded hydride ion conductor.

8. The method according to claim 4, characterized in that the method for reacting the rare earth metal source with hydrogen includes at least one of mechanical ball mill grinding, closed-system hydrogenation, and fluid-system hydrogenation.

9. The conditions for the mechanical ball mill grinding are: rotation speed of 50 to 500 revolutions per minute, ball mass ratio of 1:1 to 100:1, and H in the ball mill grinding atmosphere. ２ The method according to 8, characterized in that the partial pressure is 0.1 to 100 bar and the ball mill grinding time is 0.1 to 60 hours.

10. The aforementioned closed-system hydrogenation conditions are a temperature of -100 to 900°C, H ２ The method according to 8, characterized in that the partial pressure is 0.1 to 200 bar and the reaction time is 0.1 to 60 hours.

11. The aforementioned fluidized system hydrogenation conditions are a temperature of 20 to 900°C, H ２ Partial pressure 0.1 to 50 bar, H ２ The method according to 8, characterized in that the flow rate is 10 to 300 mL / min and the reaction time is 0.1 to 60 hours.

12. Applications of the hydride ion conductor described in any one of claims 1 to 3, and the pure hydride ion conductor and mixed hydride ion and electron conductor produced by the method described in any one of claims 4 to 11, in the construction of novel secondary batteries, fuel cells, electrochemical reactors, hydrogen separation membranes, sensors, and membrane reactors.

Images