Oxide solid electrolyte material of high-performance NASICON composite microcrystalline glass as well as preparation method and application of oxide solid electrolyte material

Abstract

The invention discloses an oxide solid electrolyte material of high-performance NASICON composite glass ceramics and a preparation method and application thereof, the chemical general formula of the oxide solid electrolyte material is Na < 3 + x + y > Zr < 2-x > A < x > Si < 2 + y > P < 1-y > O < 12 > or Na < 3 + 2x + y > Zr < 2-x > A < x > Si < 2 + y > P < 1-y > O < 12 >, x is more than 0 and less than or equal to 0.3, y is more than 0 and less than or equal to 0.2, and A is one or two of cheap metal elements such as Ca, Mg, Zn, Al, Cu, Fe and the like. Through introduction of low-valence metal elements, a glass phase electronic insulation substance containing Na, A and O elements is generated at a crystal boundary to fill the crystal boundary, so that the dendritic crystal resistance of the NASICON type oxide solid electrolyte is improved, and the wettability of the NASICON type oxide solid electrolyte and Na metal is enhanced. The ceramic material is free of rare earth metal elements, simple in process and suitable for large-scale industrial production, and the invention further provides a preparation method of the ceramic material and application of the ceramic material to preparation of an all-solid-state sodium battery.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a novel high-ionic-conductivity NASICON-type oxide solid electrolyte material, its preparation method, and its application. Background Technology

[0003] To ensure national energy security, there is an urgent need to explore new energy storage solutions besides lithium-ion batteries. In this context, sodium-ion batteries have emerged as a viable alternative. Sodium carbonate, the essential element for sodium batteries, is abundant and inexpensive on Earth. Furthermore, sodium, like lithium, belongs to Group 1 elements and possesses similar electrochemical properties, further enhancing its potential as an energy storage technology. Traditional lithium-ion batteries, on the other hand, use organic liquid electrolytes. In severe situations such as collisions or punctures during battery use, the liquid electrolyte may leak. Simultaneously, the high temperatures generated by a short circuit can induce electrolyte combustion, leading to battery fire or even explosion. This has become the biggest safety hazard associated with lithium-ion batteries.

[0004] Therefore, researching a safe, green, and efficient solid-state electrolyte has become a solution to this major problem. Sodium-ion batteries are a preferred option, but most existing sodium solid-state electrolyte materials have low ionic conductivity, resulting in poor fast-charging performance. Furthermore, the easy growth of Na dendrites at grain boundaries in solid-state electrolytes significantly reduces their dendrite resistance, severely limiting the long-cycle capability of the assembled batteries. Thus, how to balance high ionic conductivity, high dendrite resistance, and low cost in sodium solid-state electrolyte materials has become a crucial challenge that must be addressed in the mass production of sodium solid-state batteries. Summary of the Invention

[0005] To address the aforementioned problems, this invention prepares a series of high-performance NASICON composite microcrystalline glass oxide solid electrolyte materials without introducing expensive rare earth metal elements. These materials possess excellent ionic conductivity and anti-dendrying ability, and are more suitable for industrial production.

[0006] According to an embodiment of the present invention, a high-performance NASICON composite microcrystalline glass oxide solid electrolyte material is provided, wherein the general chemical formula of the ceramic material is Na. 3+x+y Zr 2-x A x Si 2+y P 1-y O 12 Or Na 3+2x+y Zr 2-x A x Si 2+y P 1-y O 12, 0 < x ≤ 0.3 and 0 < y ≤ 0.2, A is one or two of the inexpensive metallic elements such as Ca, Mg, Zn, Al, Cu, and Fe.

[0007] This embodiment modulates Na3Zr2Si2PO 12 Based on the composition of NASICON-type solid electrolyte ceramic materials with sodium fast ion conductors, ion substitution (A) is added. 2+ &A 3+ Equal-charge doping successfully enabled effective control of the size of sodium ion transport channels within the crystal structure at the atomic scale. The ionic conductivity of this ceramic material is 1.71 × 10⁻⁶. -3 S / cm to 3.10×10 - 3 Between S / cm, the ceramic crystal portion of this invention has two crystal structures: prismatic phase R3-c and monoclinic phase C2 / c. Among them, the prismatic phase R3-c, which has higher ionic conductivity, accounts for the majority, reaching up to 89.34%. At the same time, it maintains the diversity of sodium ion transport channels and has a high sodium ion transport capacity.

[0008] In sodium-ion solid electrolytes, Na3Zr2Si2PO4 has a three-dimensional spatial structure. 12 Solid electrolytes of this type have advantages such as safety, ease of preparation, high ionic conductivity, wide electrochemical window, and excellent chemical and electrochemical stability; Na3Zr2Si2PO 12 In the structure, tetrahedral PO4 and octahedral ZrO6 together form a network structure, creating structural vacancies and fillable coordination that allow sodium ions to pass through, forming Na3Zr2Si2PO4. 12 Based on the system, the evolution of lattice parameters is achieved by controlling the composition, thereby increasing the sodium ion content in the system and enhancing the sodium ion transport capacity. Furthermore, by introducing metal elements to generate glassy phase materials in situ at the grain boundaries, the grain boundary impedance is reduced, the sodium ion conduction rate at the grain boundaries is increased, and the overall electrochemical performance and electrochemical stability of NASICON solid electrolyte are improved.

[0009] This embodiment introduces a glassy phase material at the grain boundaries to accelerate the mass transfer process during sintering, thereby reducing the sintering temperature. As the sintering temperature decreases, the average grain size becomes smaller, and the filling of the glassy phase at the grain boundaries increases the overall density of the ceramic and significantly increases its mechanical strength, thus enhancing the anti-dendrying ability of the ceramic sheet in terms of mechanical properties. By introducing glass-ceramics rich in Na, A, and O elements at the grain boundaries, an electronic insulating buffer layer is formed, preventing electron leakage, inhibiting the growth of sodium dendrites, reducing dendrite problems, and improving the stability and safety of the battery.

[0010] The present invention also provides a method for preparing the above-mentioned ceramic material, comprising: In summary, the combination of Na₂CO₃, ZrO₂, SiO₂, NH₄H₂PO₄ and A x O y (2≤x&y≤3) The mixture is formed by distributing the ingredients according to the general chemical formula. After the mixture is mixed for the first time, it is pre-fired, then mixed for the second time, and then sintered.

[0011] Specifically, both the first and second mixing processes involve ball milling. In the first mixing, nitric oxide grinding balls and alcohol are added to the mixture, with a mass ratio of mixture:nitric oxide grinding balls:alcohol of 1:(3-6):(2-6). After ball milling for 10-15 hours, primary ball milling material is obtained. This primary ball milling material is dried and passed through a 200-mesh sieve to obtain dried powder, which is used for pre-firing the base material. In the second ball milling, the base material:nitric oxide grinding balls:alcohol of 1:(3-6):(2-6) mass ratio is used for ball milling for 4-8 hours to obtain secondary ball milling material. This secondary ball milling material is dried and passed through a 100-mesh sieve to obtain pre-fired powder. The pre-fired powder is dry-pressed into green bodies, which are then used for sintering to obtain ceramic materials.

[0012] Furthermore, the pre-firing is carried out using an alumina crucible at 900–1100°C for 6–8 hours.

[0013] Furthermore, sintering is carried out in a sintering furnace, with a heating rate of 4–6 °C / min and sintering at 1100–1300 °C for 10–16 h.

[0014] Furthermore, the ball milling process utilizes a sand mill ball mill.

[0015] This invention also provides an application of the above-mentioned ceramic material in the preparation of all-solid-state sodium-ion batteries, the resulting all-solid-state sodium-ion batteries... The sodium battery has a cycle life of more than 3000 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By comprehensively regulating the values ​​of x and y, the contents of Na, Zr, Si, P and A ions (A being one of the inexpensive metal elements such as Ca, Mg, Zn, Al, Cu, Fe, etc.) are controlled, so as to comprehensively regulate the lattice constant and improve the ionic conductivity, thereby ensuring that the prepared ceramic material has a highly dense microstructure, free of pores and microcracks.

[0017] The ceramic crystal portion exhibits a dual-phase structure consisting of a prismatic phase and a monoclinic phase. The presence of A ions broadens the channels for sodium ion transport within the lattice and introduces more sodium ions, resulting in a significant improvement in the ionic conductivity of this sodium-ion solid electrolyte material, reaching 3.10 × 10⁻⁶. -3 S / cm; By introducing glassy phase materials at the grain boundaries, the mass transfer process is accelerated during sintering, thereby reducing the sintering temperature and facilitating large-scale industrial production. Due to the reduction in sintering temperature and the introduction of molten glass phase material during sintering, grain growth is suppressed, resulting in grain refinement. The glass phase filling at the grain boundaries significantly increases the mechanical properties at the grain boundaries and enhances their anti-dendrying properties. By introducing glass-ceramics rich in Na, A, and O elements at the grain boundaries, an electronic insulating buffer layer is formed, which prevents electron leakage, inhibits the growth of sodium dendrites, reduces dendrite problems, and improves the stability and safety of the battery.

[0018] The raw materials used in this invention to prepare sodium-ion solid electrolyte materials are readily available and inexpensive in China, and contain no rare earth metal elements. Therefore, it has a significant advantage in large-scale production and possesses excellent commercial prospects. Moreover, the sintering temperature of the solid electrolyte ceramic material of the present invention is 1100-1300℃, which has a wide sintering temperature range and good process adaptability. This invention employs a two-stage ball milling process to achieve particle size control of the material; The all-solid-state sodium-pair battery prepared with the provided ceramic material can be stably cycled for more than 3000 hours at a current density of 0.1 mA / cm2; Attached Figure Description Figure 1 The XRD analysis results are for the solid electrolyte sheet prepared in Example 1 of this invention. Figure 2 The XRD analysis results are for the solid electrolyte sheet prepared in Example 2 of this invention. Figure 3 The XRD analysis results are for the solid electrolyte sheet prepared in Example 3 of this invention. Figure 4 The above are the EIS analysis results of the solid electrolyte sheet prepared in Example 1 of this invention; Figure 5 The above are the EIS analysis results of the solid electrolyte sheet prepared in Example 2 of this invention; Figure 6 The above are the EIS analysis results of the solid electrolyte sheet prepared in Example 3 of this invention; Figure 7 The results of cross-sectional SEM secondary electron analysis of the solid electrolyte sheet prepared in Example 3 of this invention are shown. Figure 8 The results of SEM backscattered electron analysis on the polished surface of the solid electrolyte sheet prepared in Example 3 of this invention are shown. Figure 9 The results of EDS energy dispersive spectroscopy analysis of the polished surface of the solid electrolyte sheet prepared in Example 3 of this invention are shown.

Claims

1. A high-performance NASICON composite glass-ceramic oxide solid electrolyte material, its preparation method, and its application, characterized in that, The general chemical formula for ceramic materials is Na. 3+x+y Zr 2-x A x Si 2+y P 1-y O 12 Or Na 3+2x+y Zr 2-x A x Si 2+y P 1- y O 12 0 < x ≤ 0.3 and 0 < y ≤ 0.2, A is one or two of the inexpensive metal elements such as Ca, Mg, Zn, Al, Cu, Fe, etc., and glassy phase material rich in Na, A, and O elements is introduced to fill the grain boundaries.

2. The modified NASICON-type structured sodium-ion solid electrolyte ceramic material as described in claim 1, characterized in that, The ionic conductivity of the ceramic material is 1.71 × 10⁻⁶. -3 S / cm to 3.10×10 -3 Between S / cm, the grain boundaries are filled with a glassy phase containing metallic elements, which is electronically insulating.

3. The modified NASICON-type structured sodium-ion solid electrolyte ceramic material as described in claim 1, characterized in that, It has two crystal structures: prismatic R3-c and monoclinic C2 / c. The prismatic R3-c with higher ionic conductivity is the main part, reaching up to 89.34%. The grain boundaries are filled with glassy electronic insulating material containing metal elements, which greatly enhances the resistance to dendrite formation.

4. A method for preparing a modified NASICON-type structured sodium-ion solid electrolyte ceramic material as described in any one of claims 1 to 3, characterized in that, include: The oxides of Na₂CO₃, ZrO₂, SiO₂, NH₄H₂PO₄, and metallic element A (A is one of the inexpensive metallic elements such as Ca, Mg, Zn, Al, Cu, Fe, etc.) are combined. x O y The mixture is prepared by distributing the ingredients according to the general chemical formula. After the mixture is first mixed, it is pre-fired, then mixed a second time, and finally sintered.

5. The preparation method according to claim 4, characterized in that, Both the first and second mixing processes involved ball milling. In the first mixing, nitric oxide grinding balls and alcohol were added to the mixture at a mass ratio of 1:(3-6):(2-6). After ball milling for 8-10 hours, primary ball milling material was obtained. This primary ball milling material was dried and passed through a 100-mesh sieve to obtain dried powder, which was used for pre-firing to obtain the base material. In the second ball milling, the base material, nitric oxide grinding balls, and alcohol were ball milled at a mass ratio of 1:(3-6):(2-6) for 4-8 hours to obtain secondary ball milling material. This secondary ball milling material was dried and passed through a 200-mesh sieve to obtain pre-fired powder. The pre-fired powder was dry-pressed into green bodies, which were then used for sintering to obtain ceramic materials.

6. The preparation method according to claim 4 or 5, characterized in that, Pre-firing is carried out using an alumina crucible at 900–1100℃ for 6–8 hours.

7. The preparation method according to claim 4 or 5, characterized in that, Sintering is carried out in a sintering furnace, with a heating rate of 4-6℃ / min and sintering at 1100-1300℃ for 10-16 hours.

8. The preparation method according to claim 5, characterized in that, The ball milling process uses a planetary ball mill.

9. An application of the modified NASICON-type structure sodium-ion solid electrolyte ceramic material as described in any one of claims 1 to 3, characterized in that, Used to prepare all-solid-state sodium-pair batteries.

10. The application as described in claim 9, characterized in that, The all-solid-state sodium battery has a cycle life of more than 3000 hours.

Images