Mixed ion-electron conductor and preparation method and application thereof

Abstract

The invention provides a mixed ion-electron conductor and a preparation method and application thereof, and belongs to the technical field of all-solid-state electrolyte. The preparation method comprises the following steps: firstly, carrying out ball milling treatment on sodium carbonate and titanium dioxide, and sintering to prepare Na2Ti6O13; and then mixing Na2Ti6O13 and hydride, grinding, tabletting and calcining to prepare the mixed ion-electron conductor. The valence state of titanium is effectively regulated and controlled through hydride, so that the proportion of Ti < 3 + > to Ti < 4 + > is changed, and the ionic conductivity and the electronic conductivity of the material at the room temperature are improved by introducing hydrogen.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state electrolyte technology, and in particular to a hybrid ion-electron conductor, its preparation method, and its application. Background Technology

[0002] With the continuous development of energy storage and conversion technologies, solid-state batteries, as a novel energy storage device, have attracted widespread attention. Compared to traditional liquid batteries, solid-state batteries offer higher safety, energy density, and electrochemical stability, while also being smaller, easier to compress, and more portable. Their advantages are becoming increasingly apparent, particularly in fields such as electric vehicles, wearable devices, and large-scale energy storage systems. The key to realizing all-solid-state batteries is a solid electrolyte; therefore, researching and obtaining high-performance solid electrolyte materials is of great significance.

[0003] Hybrid ion-electron conductors (MIECs), as an emerging solid-state electrolyte material, have demonstrated excellent performance in energy storage systems such as batteries, fuel cells, and supercapacitors. Compared to traditional single-ion conductors, MIECs can conduct both ions and electrons, thus significantly improving the power density and operating efficiency of batteries. Titanium oxides have attracted widespread attention due to their excellent physicochemical properties, but they still face some challenges in practical applications. For example, insufficient conductivity at low temperatures, low ion mobility, and instability at the electrolyte-electrode interface limit their application in high-efficiency solid-state batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a hybrid ion-electron conductor, its preparation method, and its application, in order to solve the problems of insufficient conductivity and low ion mobility of titanium oxide in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a mixed ion-electron conductor, comprising the following steps: (1) Sodium carbonate and titanium dioxide were ball-milled and sintered to obtain Na2Ti6O 13 ; (2) Na2Ti6O 13 After being mixed with hydrides, the mixture is ground, pressed into tablets, and calcined to obtain a mixed ion-electron conductor.

[0006] Preferably, in step (1), the ball-to-material ratio during ball milling is 25-35:1, the rotation speed is 200-600 rpm, and the time is 3-10 h.

[0007] Preferably, in step (1), the sintering temperature is 900~1200℃ and the time is 10~20h.

[0008] Preferably, in step (2), the hydride is calcium hydride, magnesium hydride, or barium hydride; the Na2Ti6O 13 The molar ratio of the hydride to the hydride is 1:2~4.

[0009] Preferably, in step (2), the grinding is carried out in an inert atmosphere for 30 to 40 minutes.

[0010] Preferably, in step (2), the calcination temperature is 450~550℃ and the time is 24~48h.

[0011] Preferably, in step (2), the calcined product is washed with an ammonium chloride methanol solution, wherein the concentration of the ammonium chloride methanol solution is 0.05~0.2mol / L.

[0012] The present invention also provides a mixed ion-electron conductor prepared by the above-described method.

[0013] The present invention also provides an application of the above-described hybrid ion-electron conductor as a solid electrolyte in an all-solid-state battery.

[0014] The beneficial effects of this invention are: The preparation of the mixed ion-electron conductor of the present invention is simple and inexpensive, and the mixed ion-electron conductor as a solid electrolyte has good stability in air.

[0015] This invention effectively modulates the valence state of titanium through hydrides, enabling Ti to achieve... 3+ With Ti 4+ The ratio changed, and the introduction of hydrogen improved the ionic conductivity and electronic conductivity of the material at room temperature. Attached Figure Description

[0016] Figure 1 Na2Ti6O prepared in Example 1 13 Na2Ti6O 13 H x -24h and Na2Ti6O prepared in Example 2 13 H x XRD pattern at -48h; Figure 2 Na2Ti6O prepared in Example 1 13 Na2Ti6O 13 H x -24h and Na2Ti6O prepared in Example 2 13 H x Electrochemical impedance spectroscopy and Arrhenius plot of the solid electrolyte at -48h, where a represents Na₂Ti₆O₂.13 Electrochemical impedance spectroscopy, b is Na2Ti6O 13 H x Electrochemical impedance spectroscopy (EIS) over 24 hours, where c represents Na₂Ti₆O₂. 13 H x Electrochemical impedance spectroscopy at -48h, d is the Arrhenius plot; Figure 3 Na2Ti6O prepared in Example 1 13 Na2Ti6O 13 H x -24h and Na2Ti6O prepared in Example 2 13 H x -48h as a solid electrolyte I -t graph, where a is Na2Ti6O 13 of I -t graph, b is Na2Ti6O 13 H x -24h I -t graph, c is Na2Ti6O 13 H x -48h I -t graph. Detailed Implementation

[0017] This invention provides a method for preparing a mixed ion-electron conductor, comprising the following steps: (1) Sodium carbonate and titanium dioxide were ball-milled and sintered to obtain Na2Ti6O 13 ; (2) Na2Ti6O 13 After being mixed with hydrides, the mixture is ground, pressed into tablets, and calcined to obtain a mixed ion-electron conductor.

[0018] In this invention, in step (1), the ball-to-material ratio during ball milling is 25-35:1, specifically 25:1, 28:1, 30:1, 32:1, or 35:1; the rotation speed is 200-600 rpm, specifically 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, or 600 rpm; and the time is 3-10 hours, specifically 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0019] In this invention, in step (1), the sintering temperature is 900~1200℃, specifically 900℃, 1000℃, 1100℃, 1200℃; the time is 10~20h, specifically 10h, 12h, 14h, 16h, 18h, 20h.

[0020] In this invention, in step (2), the hydride is calcium hydride, magnesium hydride, or barium hydride; the Na2Ti6O 13 The molar ratio of the compound to the hydride is 1:2 to 4, preferably 1:3.

[0021] In this invention, in step (2), the grinding is carried out in an inert atmosphere for a time of 30 to 40 minutes, specifically 30 minutes, 35 minutes, or 40 minutes.

[0022] In this invention, in step (2), the calcination temperature is 450~550℃, specifically 450℃, 480℃, 500℃, 520℃, 550℃; the time is 24~48h, specifically 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h.

[0023] In this invention, in step (2), the calcined product is washed with an ammonium chloride methanol solution, wherein the concentration of the ammonium chloride methanol solution is 0.05~0.2 mol / L, preferably 0.08~0.15 mol / L, and more preferably 0.1 mol / L.

[0024] In this invention, the mass-to-volume ratio of the calcined product to the ammonium chloride methanol solution during washing is 0.5~1.5g:50~150mL, preferably 0.8~1.2g:80~120mL, and more preferably 1.0g:100mL.

[0025] The present invention also provides a mixed ion-electron conductor prepared by the above-described method.

[0026] The present invention also provides an application of the above-described hybrid ion-electron conductor as a solid electrolyte in an all-solid-state battery.

[0027] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0028] Example 1

[0029] Na₂CO₃ and TiO₂ were mixed uniformly at a stoichiometric ratio of 1:6. The mixture was then transferred to a ball mill jar, and zirconia beads were added at a ball-to-material ratio of 30:1. The mixture was then ball-milled at 500 rpm for 4 hours. The milled material was then sintered using the following process parameters: heating to 1100℃ at a rate of 5℃ / min, holding at that temperature for 10 hours, and then naturally cooling to room temperature to obtain Na₂Ti₆O₅. 13 ; Na2Ti6O was prepared in a molar ratio of 1:3. 13 The product and CaH2 were placed in an agate mortar and ground thoroughly for 30 minutes under an argon atmosphere. After grinding, the product was pressed into tablets, vacuum sealed, and then calcined at 500℃ for 24 hours. After calcination, the pressed tablets were ground and washed with a 0.1 mol / L ammonium chloride methanol solution (the mass-to-volume ratio of the calcined product to the ammonium chloride methanol solution was 1.0 g: 100 mL). Finally, the tablets were dried to obtain a mixed ionic-electron conductor, denoted as Na2Ti6O. 13 H x -24h(0≤ x ≤1).

[0030] Example 2

[0031] Na2Ti6O 13 The preparation is the same as in Example 1; Na2Ti6O was prepared in a molar ratio of 1:3. 13 The product and CaH2 were placed in an agate mortar and ground thoroughly for 30 minutes under an argon atmosphere. After grinding, the product was pressed into tablets, vacuum sealed, and then calcined at 500℃ for 48 hours. After calcination, the pressed tablets were ground and washed with a 0.1 mol / L ammonium chloride methanol solution (the mass-to-volume ratio of the calcined product to the ammonium chloride methanol solution was 1.0 g: 100 mL). Finally, the tablets were dried to obtain a mixed ionic-electron conductor, denoted as Na2Ti6O. 13 H x -48h (0≤ x ≤1).

[0032] from Figure 1 It can be seen that Na2Ti6O 13 H x -24h and Na2Ti6O 13 H x -48h with Na2Ti6O 13 They have the same structure and space group C2 / m; as CaH2 reduction proceeds, the cell volume increases and the X-ray diffraction peaks shift to lower angles.

[0033] Performance testing: The Na2Ti6O prepared in Example 1 13 Na2Ti6O 13 H x -24h and Na2Ti6O prepared in Example 2 13 H x Ionic conductivity was tested at different temperatures over a period of 48 hours using a stainless steel / electrolyte / stainless steel model. The results are as follows: Figure 2 As shown. From Figure 2As can be seen, as CaH2 reduction proceeds, the ionic conductivity gradually increases and the activation energy gradually decreases; the ionic conductivity after CaH2 reduction increases by four orders of magnitude.

[0034] The Na2Ti6O prepared in Example 1 13 Na2Ti6O 13 H x -24h and Na2Ti6O prepared in Example 2 13 H x Electron conductivity tests were conducted on batteries assembled at different temperatures over a period of -48 hours using a stainless steel / solid electrolyte / stainless steel structure. The results are as follows: Figure 3 As shown. From Figure 3 It can be seen that the electronic conductivity also increases significantly as the CaH2 reduction proceeds.

[0035] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a mixed ion-electron conductor, characterized in that, Includes the following steps: (1) Sodium carbonate and titanium dioxide were ball-milled and sintered to obtain Na2Ti6O 13 ; (2) Na2Ti6O 13 After being mixed with hydrides, the mixture is ground, pressed into tablets, and calcined to obtain a mixed ion-electron conductor.

2. The method for preparing a mixed ion-electron conductor according to claim 1, characterized in that, In step (1), the ball-to-material ratio during ball milling is 25-35:1, the rotation speed is 200-600 rpm, and the time is 3-10 h.

3. The method for preparing a mixed ion-electron conductor according to claim 1 or 2, characterized in that, In step (1), the sintering temperature is 900~1200℃ and the time is 10~20h.

4. The method for preparing a mixed ion-electron conductor according to claim 3, characterized in that, In step (2), the hydride is calcium hydride, magnesium hydride, or barium hydride; the Na2Ti6O 13 The molar ratio of the hydride to the hydride is 1:2~4.

5. The method for preparing a mixed ion-electron conductor according to claim 1, 2, or 4, characterized in that, In step (2), the grinding is carried out in an inert atmosphere for 30 to 40 minutes.

6. The method for preparing a mixed ion-electron conductor according to claim 5, characterized in that, In step (2), the calcination temperature is 450~550℃ and the time is 24~48h.

7. The method for preparing a mixed ion-electron conductor according to claim 4 or 6, characterized in that, In step (2), the calcined product is washed with an ammonium chloride methanol solution, wherein the concentration of the ammonium chloride methanol solution is 0.05~0.2mol / L.

8. The mixed ion-electron conductor prepared by the method according to any one of claims 1 to 7.

9. The application of the hybrid ion-electron conductor as a solid electrolyte in all-solid-state batteries according to claim 8.

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