Solid electrolyte coated with gallium-based liquid alloy as well as preparation method and application of solid electrolyte

Abstract

The invention discloses a solid electrolyte coated with a gallium-based liquid alloy and a preparation method and application of the solid electrolyte, and the preparation method of the solid electrolyte comprises the following steps: uniformly mixing a Na source, a Zr source, a Pr source, a Si source and a P source to obtain powder, and calcining the powder to obtain precursor powder; the preparation method comprises the following steps: preparing a precursor powder, adding a binder into the precursor powder, carrying out compression molding to obtain a green body, carrying out heat preservation on the green body, calcining to obtain an NZSP: Pr solid electrolyte sheet, uniformly coating the surface of the NZSP: Pr solid electrolyte sheet with a gallium-based liquid alloy, heating, and drying to obtain the solid electrolyte coated with the gallium-based liquid alloy. The solid electrolyte provided by the invention can enhance the interface adhesion and cycling stability, and can solve the problems of poor interface compatibility, poor stability, dendritic crystal growth and the like between the solid electrolyte and the sodium metal negative electrode in the existing solid sodium metal battery.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a solid electrolyte coated with a gallium-based liquid alloy, its preparation method, and its application. Background Technology

[0002] Solid-state sodium metal batteries, as an emerging energy storage technology, possess advantages such as abundant resources, low cost, and high theoretical energy density, and are considered a strong candidate for next-generation high-energy-density batteries, especially showing potential to replace lithium-ion batteries. However, in practical applications, solid-state sodium metal batteries face serious interfacial compatibility challenges, mainly stemming from the solid-solid interface problem between the sodium metal anode and the solid electrolyte. On the one hand, the physical contact between rigid solids is difficult to achieve continuously and tightly, leading to the formation of a high-resistivity interface layer, thus hindering the effective migration of sodium ions. On the other hand, this non-uniform interfacial contact easily induces heterogeneous deposition and dendrite growth of sodium metal, resulting in battery short circuits, capacity decay, and safety hazards. The low melting point and strong reactivity of sodium metal further exacerbate interfacial instability, especially at high current densities, where the interfacial impedance increases significantly, affecting the battery's kinetic performance and cycle life.

[0003] Traditional NASICON type Na3Zr2Si2PO 12 While (NZSP) solid electrolytes possess high ionic conductivity, their rigid surface exhibits poor interfacial compatibility with sodium metal, resulting in excessively high interfacial impedance and severely limiting battery performance. To alleviate this interfacial problem, a common strategy is to introduce an intermediate layer, such as a polymer coating or a solid alloy layer. However, these methods often have limitations: polymer coatings may hinder rapid ion transport, reducing ionic conductivity; while solid alloy layers struggle to adapt to sodium deposition / stripping at high current densities and lack interfacial self-healing capabilities.

[0004] Liquid metals, as a novel interface modification material, still face significant challenges in practical applications. One is the reduction in battery cycle performance due to volume expansion during cycling, a problem particularly pronounced during charge and discharge, directly impacting the battery's long-term cycle stability. Secondly, the high surface tension of liquid metals leads to insufficient wettability with solid electrolytes, easily causing gaps or voids at the interface, resulting in increased interfacial impedance, dendrite formation, and ultimately, battery performance failure. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a solid electrolyte coated with a gallium-based liquid alloy. This method first uses a solid-state sintering method to obtain an NZSP:Pr solid electrolyte sheet doped with praseodymium (Pr), and then coats its surface with a gallium-based liquid alloy to form an intermediate layer that can stabilize the interface, thereby obtaining a solid electrolyte coated with a gallium-based liquid alloy.

[0006] Another object of the present invention is to provide a solid electrolyte coated with a gallium-based liquid alloy.

[0007] Another objective of this invention is to provide a solid-state sodium metal battery comprising a solid electrolyte coated with a gallium-based liquid alloy. This battery successfully constructs a sodium sheet / solid electrolyte interface layer that combines high sodium affinity and electrochemical stability. The intermediate layer in the solid electrolyte reduces the contact angle of the sodium sheet / solid electrolyte interface layer, improves the interfacial wettability between the sodium sheet and the solid electrolyte, provides face-to-face contact, and eliminates the space charge layer and uneven sodium deposition caused by point-to-point contact. This enhances interfacial adhesion and cycle stability, and can solve problems such as poor interfacial compatibility, poor stability, and dendrite growth between the solid electrolyte and the sodium metal anode in existing solid-state sodium metal batteries.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A method for preparing a solid electrolyte coated with a gallium-based liquid alloy includes the following steps:

[0010] Step 1: Mix Na source, Zr source, Pr source, Si source and P source evenly to obtain powder. Calcinate the powder at 1100~1300°C for 12~14h to obtain precursor powder. Add a binder to the precursor powder and press it at 10~20MPa to obtain a green body. The ratio of Na in Na source, Zr in Zr source, Pr in Pr source, Si in Si source and P in P source by molar amount is 3.795:1.7:(0.1~5):2:1. The ratio of the mass fraction of precursor powder to the volume fraction of binder is (0.5~0.6):0.05. The unit of mass fraction is g, and the unit of volume fraction is mL. The binder is a polyvinyl alcohol aqueous solution.

[0011] In step 1, the Na source is sodium carbonate, the Zr source is zirconium oxide, and the Pr source is praseodymium undecylenium oxide (Pr6O). 11 The Si source is silicon dioxide, and the P source is ammonium dihydrogen phosphate.

[0012] In step 1, the polyvinyl alcohol aqueous solution comprises polyvinyl alcohol and water, and the ratio of polyvinyl alcohol to water in the polyvinyl alcohol aqueous solution is (10~15):(85~90) by mass.

[0013] In step 1, the mixing is achieved by ball milling. The ball milling is a wet ball milling process, which is performed for 0.5 to 1 hour until the mixture is uniform. After ball milling, the mixture is dried at a temperature of 80 to 100°C for 3 to 4 hours.

[0014] Step 2: The blank is first kept at 600~650°C for 2~3 hours, and then calcined at 1100~1300°C for 12~14 hours to obtain NZSP:Pr solid electrolyte sheet;

[0015] In step 2, the diameter of the NZSP:Pr solid electrolyte sheet is 14~16mm.

[0016] Step 3: A gallium-based liquid alloy is uniformly coated on the surface of an NZSP:Pr solid electrolyte sheet at 60-80°C, heated at 40-100°C for 0.5-1h, and dried to obtain a solid electrolyte coated with a gallium-based liquid alloy. The gallium-based liquid alloy includes Ga, Sn and Zn, and the ratio of Ga, Sn and Zn in the gallium-based liquid alloy by mass is (80-90):(5-15):(0.5-5).

[0017] In step 3, after drying, a gallium-based liquid alloy forms an intermediate layer with a thickness of 0.5~5µm.

[0018] In step 3, the method for preparing gallium-based liquid alloy includes: mixing liquid metals Ga, Sn and Zn uniformly, grinding them, and obtaining gallium-based liquid alloy (Ga-Zn-Sn liquid alloy).

[0019] In step 3, the surface of the NZSP:Pr solid electrolyte sheet is per 1 cm 2 Coated with 1~4mg of gallium-based liquid alloy.

[0020] In step 3, the drying temperature is 80~100°C and the drying time is 8~10h.

[0021] In step 3, the coating method is a brush coating method.

[0022] The solid electrolyte coated with gallium-based liquid alloy is obtained by the above preparation method.

[0023] A solid sodium metal battery includes: a solid electrolyte coated with a gallium-based liquid alloy.

[0024] The above-mentioned applications of solid electrolytes in batteries.

[0025] Compared with the prior art, the beneficial effects of the present invention include:

[0026] 1. Improved interfacial contact and reduced impedance. The preparation method of this invention introduces a gallium-based liquid alloy (Ga-Zn-Sn liquid alloy, which has a low melting point and excellent wettability) onto the surface of the NZSP:Pr solid electrolyte sheet. This allows the gallium-based liquid alloy to spontaneously fill the interfacial voids, forming a continuous composite interface. This composite interface provides a uniform sodium ion transport channel, which reduces interfacial impedance. The CR2032 type solid sodium metal symmetric battery assembled from the solid electrolyte coated with the gallium-based liquid alloy of this invention has an interfacial impedance of only 3Ω.

[0027] 2. Suppressing sodium dendrite growth and regulating ion flux. In the solid electrolyte coated with gallium-based liquid alloy of this invention, the Ga-Zn-Sn liquid alloy undergoes a spontaneous alloying reaction with the sodium sheet to generate stable alloy phases (such as Ga-Na, Sn-Na, and Zn-Na). This can regulate the interfacial electric field distribution, reduce the nucleation barrier, and homogenize the ion flux distribution, thereby effectively suppressing tip discharge and dendrite formation, and improving battery safety.

[0028] 3. Enhanced self-healing capability and cycle stability. The CR2032 type solid-state sodium metal symmetric battery assembled with a solid electrolyte coated with a gallium-based liquid alloy, as described in this invention, achieves a cycle stability of 0.4 mA cm⁻¹. -2 The Ga-Zn-Sn liquid alloy of this invention exhibits fluidity and self-healing properties, enabling it to dynamically repair interfacial cracks, alleviate mechanical stress caused by volume changes, and maintain a stable electrochemical interface, thereby significantly improving the cycle life and kinetic performance of the battery. Attached Figure Description

[0029] Figure 1 The images show actual photos of the NZSP:Pr solid electrolyte sheet and GZS@NZSP:Pr obtained in Example 1.

[0030] Figure 2 The images show (a) SEM images and (b) to (h) elemental distribution diagrams of the sodium sheet / solid electrolyte interface in the CR2032 solid sodium metal symmetric battery obtained in Example 1.

[0031] Figure 3 The critical current density test curve of the CR2032 solid sodium metal symmetric battery obtained in Example 1;

[0032] Figure 4 The critical current density test curve of the CR2032 solid sodium metal symmetric battery obtained in Example 2;

[0033] Figure 5 The critical current density test curve of the CR2032 solid sodium metal symmetric battery obtained in Example 3;

[0034] Figure 6 The critical current density test curve of the CR2032 solid sodium metal symmetric battery obtained in Example 4;

[0035] Figure 7 The critical current density test curve of the CR2032 solid sodium metal symmetric battery obtained in Example 5;

[0036] Figure 8 The Nyquist plot of the interface impedance of the CR2032 solid sodium metal symmetric cell obtained in Example 1 is shown.

[0037] Figure 9 The Nyquist plot of the interface impedance of the CR2032 solid sodium metal symmetric cell obtained in Example 2 is shown.

[0038] Figure 10 The Nyquist plot of the interface impedance of the CR2032 solid sodium metal symmetric cell obtained in Example 3 is shown.

[0039] Figure 11 The Nyquist plot of the interface impedance of the CR2032 solid sodium metal symmetric cell obtained in Example 4 is shown.

[0040] Figure 12 The Nyquist plot of the interface impedance test of the CR2032 solid sodium metal symmetric battery obtained in Example 5;

[0041] Figure 13 The CR2032 type solid sodium metal symmetric cell obtained in Example 1 was used at 0.4 mA cm⁻¹ -2 Current density and 0.8 mAh cm⁻¹ -2 Cyclic stability under areal capacity;

[0042] Figure 14 The CR2032 type solid sodium metal symmetric cell obtained in Example 1 was used at 0.5 mA cm⁻¹ -2 Current density and 1mAhcm -2 Cyclic stability under areal capacity;

[0043] Figure 15 The CR2032 type solid sodium metal symmetric cell obtained in Example 5 was tested at 0.4 mA cm⁻¹. -2 Current density and 0.8 mAh cm⁻¹ -2 Cyclic stability under areal capacity;

[0044] Figure 16 The graph shows the cycle performance of the CR2032 sodium metal full cell obtained in Example 1 and the CR2032 sodium metal full cell obtained in Example 5 at 1C.

[0045] Figure 17The charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 1 is shown at 1C.

[0046] Figure 18 This is a partially enlarged view of the charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 1 at 1C.

[0047] Figure 19 The charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 5 at 1C;

[0048] Figure 20 This is a partially enlarged view of the charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 5 at 1C.

[0049] Figure 21 The rate performance of the CR2032 sodium metal full cell obtained in Example 1 and the CR2032 sodium metal full cell obtained in Example 5 are shown. Detailed Implementation

[0050] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0051] This invention constructs an enhanced sodium-solid electrolyte interface by coating a Ga-Zn-Sn liquid alloy onto the surface of an NZSP:Pr solid electrolyte sheet, forming an intermediate layer that combines high interfacial compatibility, strong dendrite suppression, and electrochemical stability. Within the intermediate layer, the Ga-Zn-Sn liquid alloy spontaneously alloys with sodium, forming stable Na-Ga, Na-Sn, and Na-Zn alloys. This enhances the interfacial bonding between the sodium sheet and the solid electrolyte, while mitigating the volume expansion caused by sodium deposition / exfoliation and inhibiting sodium dendrite growth, thereby improving the cycle life and safety of the solid sodium metal battery.

[0052] Source of raw materials used:

[0053]

[0054] Source of instruments used:

[0055]

[0056] In the following embodiments, NZSP:Pr solid electrolyte sheets were prepared by solid-state sintering. These sheets are praseodymium (Pr)-doped solid electrolyte sheets with the molecular formula Na. 3.3 Zr 1.7 Pr 0.3 Si2PO 12 .

[0057] In the following examples, the electrolyte is a commercially available NaClO4 electrolyte, purchased from Duoduo Chemical Reagent Network (model NC-013). The electrolyte includes: solvent, NaClO4 and fluoroethylene carbonate (FEC). The concentration of NaClO4 in the electrolyte is 1M, the content of fluoroethylene carbonate (FEC) in the electrolyte is 5wt%, and the solvent is a mixture of EC (ethylene carbonate) and DMC (dimethyl carbonate) in a volume ratio of 1:1.

[0058] Example 1

[0059] A method for preparing a solid electrolyte coated with a gallium-based liquid alloy (Ga-Zn-Sn liquid alloy) includes the following steps:

[0060] Step 1: Place the raw materials, 40 mL of anhydrous ethanol, and 40 zirconium oxide grinding beads into a grinding jar. The raw materials include: Na source (sodium carbonate, 8.045 g), Zr source (zirconia), and Pr source (praseodymium undecyne oxide, Pr6O). 11 The raw materials were wet-milled at 1200 rpm for 1 hour using a ball mill jar, Si (silicon dioxide), and P (ammonium dihydrogen phosphate) sources. The mixture was then dried in a 100°C oven for 3 hours to obtain a uniform powder. This powder was then calcined in a muffle furnace at 1100°C for 12 hours (air atmosphere) to obtain a precursor powder with preliminary phase formation. A binder was added dropwise to the precursor powder, and the mixture was ground to ensure uniform mixing. The powder was then pressed at 10 MPa for 100 seconds to form a 16 mm diameter blank. The Na source contained Na... The ratio of Zr in the Zr source, Pr in the Pr source, Si in the Si source, and P in the P source is 3.795:1.7:0.3:2:1 (when feeding, the Na source is in excess of 15 wt.% relative to Na in the molecular formula to make up for the mass lost due to volatilization during heat treatment); the ratio of the mass parts of the precursor powder to the volume parts of the binder is 0.5:0.05, where the mass parts are in g and the volume parts are in mL. The binder is a polyvinyl alcohol aqueous solution, which is a mixture of polyvinyl alcohol and water. By mass parts, the ratio of polyvinyl alcohol to water in the polyvinyl alcohol aqueous solution is 10:90.

[0061] Step 2: The billet is placed in a muffle furnace and heated to 650°C for 2 hours in air to remove polyvinyl alcohol. Then, the temperature is raised to 1200°C and calcined for 12 hours in air to obtain NZSP:Pr solid electrolyte sheets (diameter 15±1 mm, thickness 1 mm). The ionic conductivity was measured to be 1.3 × 10⁻⁶. -3 ±5×10 -5 S cm -1 ;

[0062] Step 3: Use a brush to uniformly coat the upper surface (circular end face) of the NZSP:Pr solid electrolyte sheet with 80°C gallium-based liquid alloy. Place it on a heating table and heat at 80°C for 0.5h to enhance the affinity between the gallium-based liquid alloy and the upper surface. Dry at 80°C for 8h to form an intermediate layer of gallium-based liquid alloy on the upper surface of the NZSP:Pr solid electrolyte sheet, and obtain a solid electrolyte with one side coated with gallium-based liquid alloy, which is named GZS@NZSP:Pr.

[0063] A gallium-based liquid alloy was uniformly coated onto the lower surface of GZS@NZSP:Pr using a brush. The substrate was then placed on a heating stage and heated at 80°C for 0.5 hours to enhance the affinity between the gallium-based liquid alloy and the surface. After drying at 80°C for 8 hours, the gallium-based liquid alloy formed another intermediate layer on the lower surface of the NZSP:Pr solid electrolyte sheet, resulting in a solid electrolyte coated on both sides with gallium-based liquid alloy. This solid electrolyte was named 2GZS@NZSP:Pr.

[0064] The gallium-based liquid alloy consists of Ga, Sn, and Zn, with a mass ratio of 86.3:10.8:2.9. The thickness of the intermediate layer on each surface is 2±1µm. The NZSP:Pr solid electrolyte sheet has a thickness of 1cm on both the upper and lower surfaces. 2 Coated with 2mg of gallium-based liquid alloy;

[0065] The method for preparing gallium-based liquid alloys includes: mixing liquid metal Ga, Sn particles and Zn particles evenly, grinding for 30 minutes to obtain a gallium-based liquid alloy (Ga-Zn-Sn liquid alloy) that is liquid at room temperature.

[0066] Figure 1 These are photographs of the NZSP:Pr solid electrolyte sheet and GZS@NZSP:Pr obtained in Example 1, where (a) is the NZSP:Pr solid electrolyte sheet and (b) is GZS@NZSP:Pr. Figure 1 It can be seen that the surface of the Pr-doped NZSP:Pr solid electrolyte sheet (original) is pale yellow-green and smooth; after coating its surface with Ga-Zn-Sn liquid alloy (gallium-based liquid alloy), the surface of the solid electrolyte is covered with a uniform silver-gray liquid alloy layer (intermediate layer), indicating that the gallium-based liquid alloy was successfully coated on the surface of the NZSP:Pr solid electrolyte sheet.

[0067] Example 2

[0068] A method for preparing a solid electrolyte coated with a gallium-based liquid alloy (Ga-Zn liquid alloy) is basically the same as the preparation method of "2GZS@NZSP:Pr" in Example 1, except that the gallium-based liquid alloy is used in step 3.

[0069] In this embodiment, the gallium-based liquid alloy is Ga and Zn, and the ratio of Ga to Zn in the gallium-based liquid alloy is 99:1 by mass. The solid electrolyte obtained in this embodiment is named 2GZ@NZSP:Pr.

[0070] In this embodiment, the method for preparing gallium-based liquid alloy includes: mixing liquid metal Ga and Zn particles evenly, grinding for 30 minutes to obtain a gallium-based liquid alloy that is liquid at room temperature.

[0071] Example 3

[0072] A method for preparing a solid electrolyte coated with a gallium-based liquid alloy (Ga-Sn liquid alloy) is basically the same as the preparation method of "2GZS@NZSP:Pr" in Example 1, except that the gallium-based liquid alloy is used in step 3.

[0073] In this embodiment, the gallium-based liquid alloy is Ga and Sn, and the ratio of Ga to Sn in the gallium-based liquid alloy is 88.9:10.1 by mass. The solid electrolyte obtained in this embodiment is named 2GS@NZSP:Pr.

[0074] In this embodiment, the method for preparing gallium-based liquid alloy includes: mixing liquid metal Ga and Sn particles evenly, grinding for 30 minutes, and obtaining a gallium-based liquid alloy that is liquid at room temperature.

[0075] Example 4

[0076] A method for preparing a solid electrolyte coated with liquid gallium metal (liquid metal Ga) is basically the same as the preparation method of "2GZS@NZSP:Pr" in Example 1, the only difference being that in this example, the gallium-based liquid alloy in Example 1 is replaced with "liquid metal Ga". The solid electrolyte obtained in this example is named 2G@NZSP:Pr.

[0077] Example 5 (for comparison)

[0078] A solid electrolyte, which is the NZSP:Pr solid electrolyte sheet of Example 1.

[0079] Example 6

[0080] A method for assembling a CR2032 type solid sodium metal symmetric battery includes: assembling the battery in a super-clean glove box in the following order: negative electrode shell, buffer sheet (10 mm diameter nickel foam), sodium sheet, solid electrolyte, sodium sheet, buffer sheet (10 mm diameter nickel foam), and positive electrode shell, to obtain a CR2032 type solid sodium metal symmetric battery. The super-clean glove box is filled with argon gas, and the oxygen and water content are both below 0.01 ppm. The solid electrolyte is one of the following: 2GZS@NZSP:Pr obtained in Example 1, 2GZ@NZSP:Pr obtained in Example 2, 2GS@NZSP:Pr obtained in Example 3, 2G@NZSP:Pr obtained in Example 4, and solid electrolyte obtained in Example 5.

[0081] SEM and EDS tests were performed on the cross-section of the sodium sheet / solid electrolyte interface on any side of the CR2032 solid sodium metal symmetric battery obtained in Example 1. The results are as follows: Figure 2 As shown. (a) is the morphology image obtained from SEM testing, and (b) to (h) are elemental distribution diagrams of each element in the cross-section. The elements in (b) to (h) are, in order, Na, Ga, Zn, Zr, Si, Pr, and Sn. Figure 2 It can be seen that, in a microfluidic state, the Ga-Zn-Sn liquid alloy (gallium-based liquid alloy) uniformly fills the micropores on the surface of the NZSP:Pr solid electrolyte sheet, forming a continuous interface with Ga, Zn, and Sn elements uniformly distributed within the interface (e.g., ...). Figure 2 (As shown in (c), (d), and (h)). This is attributed to the low melting point and excellent wettability of the gallium-based liquid alloy, which allows the gallium-based liquid alloy to spontaneously fill the interfacial pores, forming a composite interface between the sodium sheet, the Ga-Zn-Sn liquid alloy, and the NZSP:Pr solid electrolyte sheet. This composite interface is beneficial for providing a uniform sodium ion transport channel, fundamentally reducing interfacial impedance and enhancing ion conductivity. Figure 2 In (a), the area marked by the yellow dashed line represents the interface layer transitioning from the gallium-based liquid alloy to the NZSP:Pr solid electrolyte sheet. It can be observed that the gallium-based liquid alloy and the surface of the NZSP:Pr solid electrolyte sheet are in close contact and highly adhered. Above this area is the contact layer between the sodium sheet and the Ga-Zn-Sn liquid alloy (gallium-based liquid alloy). When the Ga-Zn-Sn liquid alloy is introduced onto the NZSP:Pr solid electrolyte sheet, a spontaneous alloying reaction occurs between the Ga-Zn-Sn liquid alloy and the sodium sheet, generating stable alloy phases (such as Ga-Na, Sn-Na, and Zn-Na). Below this area is the NZSP:Pr solid electrolyte sheet, where micropores can be seen on its surface.

[0082] Critical current density tests were conducted using the LAND CT2001A battery cycling test system to assess interface stability under high current. The test method is as follows: At room temperature, the CR2032 solid-state sodium metal symmetric battery was tested using the LAND CT2001A battery cycling test system with progressively increasing current density. The progressively increasing current density included starting from 0.1 mA cm⁻¹. -2 Start with 0.05mA cm -2 The step size is [number], with constant current deposition for 0.5 hours per step until a micro-short circuit occurs; the CR2032 solid-state sodium metal symmetric cell is one of the CR2032 solid-state sodium metal symmetric cells obtained in Examples 1-5. The critical current density test curve is shown below. Figures 3-7 As shown, Figure 3 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 1. Figure 4 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 2. Figure 5 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 3. Figure 6 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 4. Figure 7 The CR2032 solid sodium metal symmetric cell obtained in Example 5 is shown.

[0083] Depend on Figure 3 It can be seen that the critical current density of the CR2032 type solid sodium metal symmetric battery obtained in Example 1 is as high as 1.45 mA cm⁻¹. -2 The stable voltage curve indicates that the Ga-Zn-Sn liquid alloy (gallium-based liquid alloy) effectively suppressed dendrite growth. The ternary alloy composed of Ga-Zn-Sn liquid alloy formed a multi-component Na alloy phase, such as Na-Ga, Na-Sn, and Na-Zn, significantly improving the critical current density. This demonstrates that the CR2032 solid-state sodium metal symmetric battery obtained in Example 1 exhibits superior dendrite suppression capability at high current densities. This is attributed to the strong alloying ability and deformable characteristics of the Ga-Zn-Sn liquid alloy, which can dynamically repair interface defects and regulate the electric field distribution. Figure 4 It can be seen that the critical current density of the CR2032 type solid sodium metal symmetric battery obtained in Example 2 is 1.15 mA cm⁻¹. -2 The value is slightly lower than in Example 1, which may be due to the lack of Sn component resulting in fewer alloying phases and a weakened ability to modulate the interfacial electric field. Figure 5 It can be seen that the critical current density of the CR2032 type solid sodium metal symmetric battery obtained in Example 3 is 1.0 mA cm⁻¹. -2 This indicates that adding Sn improves the alloy's stability, but the lack of Zn affects its self-healing properties (the ability to dynamically repair interface defects). Figure 6It can be seen that the critical current density of the CR2032 type solid sodium metal symmetric battery obtained in Example 4 is 0.9 mA cm⁻¹. -2 This indicates that while liquid Ga can provide wettability, the lack of multi-element alloying prevents sufficient homogenization of ion flux. Figure 7 It can be seen that the CR2032 type solid sodium metal symmetric battery obtained in Example 5 has the lowest critical current density, which is only 0.55 mA cm⁻¹. -2 The voltage curve shows sharp fluctuations in the early stage, reflecting that poor solid-solid interface contact easily induces dendrites.

[0084] Electrochemical impedance spectroscopy (EIS) was performed on a CR2032 solid-state sodium metal symmetric solar cell using a CHI760E electrochemical workstation. EIS measurements were conducted at open-circuit potential, with a frequency range of 100 kHz to 0.01 Hz. The interfacial resistance of the CR2032 solid-state sodium metal symmetric solar cell was quantified by fitting a Nyquist plot. The results are as follows: Figures 8-12 As shown, Figure 8 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 1. Figure 9 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 2. Figure 10 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 3. Figure 11 This refers to the CR2032 type solid sodium metal symmetric battery obtained in Example 4. Figure 12 The CR2032 solid sodium metal symmetric cell obtained in Example 5 is shown.

[0085] according to Figures 8-12 It can be seen that the CR2032 type solid sodium metal symmetric solar cell obtained in Example 1 has the lowest interfacial impedance and the best performance. From Figure 8 As can be seen from the Nyquist plot of the CR2032 solid-state sodium metal symmetric battery obtained in Example 1, its semicircle diameter is the smallest (the smaller the semicircle diameter, the smaller the interfacial impedance and the optimal reaction kinetics), with an interfacial impedance of 3Ω. This indicates that the intermediate layer formed by the Ga-Zn-Sn liquid alloy (gallium-based liquid alloy) significantly reduces the interfacial impedance. Figure 9 It can be seen that the interfacial impedance of the CR2032 type solid sodium metal symmetric cell obtained in Example 2 is 7Ω, which is slightly higher than that in Example 1. Figure 10 It can be seen that the interfacial impedance of the CR2032 type solid sodium metal symmetric cell obtained in Example 3 is 9Ω, indicating that although the Sn component helps to reduce the impedance, its interfacial charge transfer kinetics are still inferior to those of Example 1. Figure 11 It can be seen that the interfacial impedance of the CR2032 solid-state sodium metal symmetric solar cell obtained in Example 4 is 12Ω, which is higher than that of Examples 1-3. Figure 12It is evident that the interfacial impedance of the CR2032 solid-state sodium metal symmetric battery obtained in Example 5 is as high as 15Ω, indicating that interfacial transport at the solid-solid contact interface of the sodium sheet / solid electrolyte is hindered, resulting in sluggish ion diffusion. Therefore, in the CR2032 solid-state sodium metal symmetric battery obtained in Example 1, the gallium-based liquid alloy effectively fills the voids, forming a continuous ion pathway, and enhances interfacial affinity through alloying reactions, significantly increasing the critical current density and reducing the interfacial impedance, demonstrating the synergistic effect of the Ga-Zn-Sn liquid alloy multi-component composition.

[0086] To evaluate the interface stability and cycle life of the battery, the CR2032 solid-state sodium metal symmetric battery obtained in Example 1 was tested at 0.4 mA cm⁻¹. -2 Current density, 0.8 mAh cm⁻¹ -2 The basic conditions for areal capacity and 0.5mA cm -2 Current density, 1mAh cm -2 Constant current charge-discharge tests were conducted under high load conditions with high areal capacity; the CR2032 solid sodium metal symmetric battery obtained in Example 5 was subjected to a constant current charge-discharge test at 0.4 mA cm⁻¹. -2 Current density, 0.8 mAh cm⁻¹ -2 Constant current charge-discharge tests were conducted under the baseline conditions of areal capacity. The obtained cycle stability test results are as follows: Figures 13-15 As shown, Figure 13 The results for the CR2032 solid-state sodium metal symmetric battery obtained in Example 1 are under the basic conditions. Figure 14 The results of the CR2032 solid-state sodium metal symmetric solar cell obtained in Example 1 under high load conditions are shown. Figure 15 The results of the CR2032 solid sodium metal symmetric battery obtained in Example 5 under the basic conditions.

[0087] Depend on Figure 13 It can be seen that the CR2032 type solid sodium metal symmetric battery obtained in Example 1 has a 0.4 mA cm⁻¹ ampere-ampere capability. -2 Current density, 0.8 mAh cm⁻¹ -2 At areal capacity, after 5000 hours of cycling (approximately 208 days), the sodium deposition / stripping overpotential is only 20 mV; this is further demonstrated by the high current density of 0.5 mA cm⁻¹. -2 and high surface capacity 1mAh cm -2 It can still cycle stably for 800 hours under certain conditions, with a sodium deposition / stripping overpotential of 35mV (e.g. Figure 14 (As shown). This indicates that the Ga-Zn-Sn liquid alloy effectively enhances the stability of the sodium sheet / solid electrolyte interface structure. In contrast, the CR2032 solid-state sodium metal symmetric battery obtained in Example 5 exhibits a performance of 0.4 mA cm⁻¹. -2 Current density, 0.8 mAh / cm³ -2At the given capacity, a short circuit occurs after 100 hours of cycling (e.g. Figure 15 (As shown). This may be due to the instability of the solid-solid weak interface contact, making it difficult to ensure efficient interfacial ion / electron transport, and making it impossible to avoid dendrite growth, which in turn leads to a rapid deterioration in cycle stability.

[0088] Example 7

[0089] A method for assembling a CR2032 sodium metal full cell includes: assembling the following components in a super-clean glove box in the following order: negative electrode shell, buffer sheet (10 mm diameter nickel foam), sodium sheet, solid electrolyte, positive electrode sheet, buffer sheet (10 mm diameter nickel foam), and positive electrode shell to obtain a CR2032 sodium metal full cell. The super-clean glove box is filled with argon gas, and the oxygen and water content are both below 0.01 ppm. The solid electrolyte is either GZS@NZSP:Pr obtained in Example 1 or the solid electrolyte obtained in Example 5. The electrolyte used is NaClO4 electrolyte (NC-013, purchased from Duoduo Chemical Reagents). 10 μL of electrolyte is immersed at the interface between the positive electrode sheet and the solid electrolyte.

[0090] The preparation method of the positive electrode sheet includes: uniformly dispersing active material (Na3V2(PO4)3, NVP, 8 mg), acetylene black, and polyvinylidene fluoride (PVDF) in 500 μL of N-methylpyrrolidone (NMP), stirring for 12 h to obtain a positive electrode slurry. The ratio of active material, acetylene black, and PVDF by mass is 80:10:10. The positive electrode slurry is uniformly coated onto an aluminum foil current collector, dried overnight in a 100°C forced-air drying oven, and the dried aluminum foil is punched into a 12 mm diameter disc as the positive electrode sheet. The loading of active material (NVP) on the positive electrode sheet is 1.5 mg / cm³. -2 .

[0091] The CR2032 sodium metal full cell underwent 250 cycle tests to evaluate its cycle stability and capacity decay. The voltage window was set to 2.5–3.8 V, and the test current density was 1 C (1 C = 117 mAh g⁻¹). -1 The CR2032 sodium metal full cell is either the CR2032 sodium metal full cell obtained in Example 1 or the CR2032 sodium metal full cell obtained in Example 5. Its discharge specific capacity as a function of cycle number is shown in the curve. Figure 16 As shown, the charge-discharge curves of the CR2032 sodium metal full cell obtained in Example 1 at 1C are as follows. Figure 17 As shown in the figure, an enlarged view of the charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 1 at 1C is shown. Figure 18 As shown, the charge-discharge curves of the CR2032 sodium metal full cell obtained in Example 5 at 1C are as follows. Figure 19As shown in the figure, an enlarged view of the charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 5 at 1C is shown. Figure 20 As shown.

[0092] Depend on Figure 16 It can be seen that the initial discharge specific capacity of the CR2032 sodium metal full cell obtained in Example 1 is 106.3 mAh g. -1 Its discharge specific capacity after 250 cycles is 101.4 mAh g. -1 The capacity retention rate of the CR2032 sodium metal full cell obtained in Example 1 was 95.39%. The initial discharge specific capacity of the CR2032 sodium metal full cell obtained in Example 5 was 90.2 mAh g⁻¹. -1 After 250 cycles, its discharge specific capacity decayed to 59.1 mAh g. -1 The capacity retention rate of the CR2032 sodium metal full cell obtained in Example 5 was only 65.5%.

[0093] Depend on Figure 17 and Figure 18 It can be seen that the charge-discharge curve of the CR2032 sodium metal full cell obtained in Example 1 has a flat plateau. The voltage difference between the charging and discharging voltages in the first cycle is 21 mV, and after 250 cycles, the voltage difference between the charging and discharging voltages is 36.8 mV. This indicates that the CR2032 sodium metal full cell obtained in Example 1 has small voltage polarization and excellent ion transport kinetics. In contrast, the voltage difference between the charging and discharging voltages of the CR2032 sodium metal full cell obtained in Example 5 is 200 mV in the first cycle, and after 250 cycles, the voltage difference between the charging and discharging voltages suddenly increases to 470 mV (e.g., ...). Figure 19 and Figure 20 (As shown).

[0094] Within a fixed voltage window (2.5~3.8V), the rate performance of the CR2032 sodium metal full cell obtained in Example 1 or Example 5 was evaluated. The test employed a multi-step constant current charge-discharge method: the cells were cycled 10 times each at current densities of 0.5, 1, 2, 5, and 10C, and finally cycled 10 times at 0.5C to evaluate the capacity retention of the cells at different current densities. The results are as follows: Figure 21 As shown, by Figure 21 It can be seen that the specific discharge capacity of the CR2032 sodium metal full cell obtained in Example 1 after 5 cycles at a current density of 0.5C is 107.5 mAh g. -1 It still retains 100.3 mAh g after 5 cycles at a current density as high as 10C. -1The specific capacity and rate capacity retention rate were 93.3%. The CR2032 sodium metal full cell obtained in Example 5 had a discharge specific capacity of 101.4 mAh g after 5 cycles at a current density of 0.5C. -1 It only has a capacity of 56 mAh g after 5 cycles at a current density of 5C. -1 The specific capacity and rate capacity retention rate of the CR2032 sodium metal full cell obtained in Example 1 are only 55.2%. This indicates that the intermediate layer formed by the Ga-Zn-Sn liquid alloy at the interface of the sodium sheet / solid electrolyte significantly improves the interfacial ion transport kinetics, reduces the sodium deposition / stripping overpotential, and thus promotes the uniform deposition / stripping behavior of sodium, thereby effectively improving the cycle stability and rate performance of the CR2032 sodium metal full cell.

[0095] The solid-state sodium metal battery obtained in this invention uses a Ga-Zn-Sn liquid alloy as an intermediate layer to modify the surface of an NZSP:Pr solid electrolyte sheet. This design enhances the electrochemical performance of the battery through the synergistic effect of multiple components. The intermediate layer formed by the Ga-Zn-Sn liquid alloy exhibits excellent performance in reducing interfacial impedance, increasing critical current density, dendrite suppression, and cycle stability. This is due to: the wettability and filling effect of the Ga-Zn-Sn liquid alloy (gallium-based liquid alloy), which achieves a composite interface; the spontaneous alloying of the multi-element alloy phase effectively homogenizes the electric field distribution and ion flux, thereby promoting uniform sodium metal deposition / exfoliation; and the strong deformation properties of the Ga-Zn-Sn liquid alloy (gallium-based liquid alloy) endow it with self-healing properties, effectively alleviating mechanical stress and suppressing dendrite growth.

[0096] This invention provides a solid-state battery interface modification strategy that enhances the sodium sheet / solid electrolyte interface contact, improves interface stability, enhances interface ion transport kinetics, and inhibits sodium dendrite growth. It is not only applicable to solid-state sodium metal batteries, but can also be extended to lithium / potassium systems, promoting the development of high-energy-density and high-safety solid-state alkali metal batteries.

[0097] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a solid electrolyte coated with a gallium-based liquid alloy, characterized in that, Includes the following steps: Step 1: Mix Na source, Zr source, Pr source, Si source and P source evenly to obtain powder. Calcinate the powder at 1100~1300°C for 12~14h to obtain precursor powder. Add a binder to the precursor powder and press it at 10~20MPa to obtain a green body. The ratio of Na in Na source, Zr in Zr source, Pr in Pr source, Si in Si source and P in P source by molar amount is 3.795:1.7:(0.1~5):2:

1. The ratio of the mass fraction of precursor powder to the volume fraction of binder is (0.5~0.6):0.

05. The unit of mass fraction is g, and the unit of volume fraction is mL. The binder is a polyvinyl alcohol aqueous solution. Step 2: The blank is first kept at 600~650°C for 2~3 hours, and then calcined at 1100~1300°C for 12~14 hours to obtain NZSP:Pr solid electrolyte sheet; Step 3: A gallium-based liquid alloy is uniformly coated on the surface of an NZSP:Pr solid electrolyte sheet at 60-80°C, heated at 40-100°C for 0.5-1h, and dried to obtain a solid electrolyte coated with a gallium-based liquid alloy. The gallium-based liquid alloy includes Ga, Sn and Zn, and the ratio of Ga, Sn and Zn in the gallium-based liquid alloy by mass is (80-90):(5-15):(0.5-5).

2. The preparation method according to claim 1, characterized in that, In step 1, the Na source is sodium carbonate, the Zr source is zirconium oxide, the Pr source is praseodymium undecyloxide, the Si source is silicon dioxide, and the P source is ammonium dihydrogen phosphate.

3. The preparation method according to claim 1, characterized in that, In step 1, the polyvinyl alcohol aqueous solution comprises polyvinyl alcohol and water, and the ratio of polyvinyl alcohol to water in the polyvinyl alcohol aqueous solution is (10~15):(85~90) by mass.

4. The preparation method according to claim 1, characterized in that, In step 1, the mixing is achieved by ball milling. The ball milling is a wet ball milling process, which is performed for 0.5 to 1 hour until the mixture is uniform. After ball milling, the mixture is dried at a temperature of 80 to 100°C for 3 to 4 hours.

5. The preparation method according to claim 1, characterized in that, In step 2, the diameter of the NZSP:Pr solid electrolyte sheet is 14~16mm.

6. The preparation method according to claim 1, characterized in that, In step 3, after drying, a gallium-based liquid alloy forms an intermediate layer with a thickness of 0.5~5µm.

7. The preparation method according to claim 1, characterized in that, In step 3, the method for preparing gallium-based liquid alloy includes: mixing liquid metals Ga, Sn and Zn uniformly, grinding them, and obtaining gallium-based liquid alloy; NZSP: Pr solid electrolyte sheet surface per 1cm 2 Coated with 1~4mg of gallium-based liquid alloy.

8. A solid electrolyte coated with a gallium-based liquid alloy obtained by the preparation method according to any one of claims 1 to 7.

9. A solid-state sodium metal battery, comprising: The solid electrolyte coated with a gallium-based liquid alloy as described in claim 8.

10. The application of the solid electrolyte coated with gallium-based liquid alloy as described in claim 8 in a battery.

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