Preparation method and battery of all-solid-state battery based on NaAlCl4 electrolyte

Abstract

This invention discloses a method for preparing an all-solid-state battery and the battery itself. The method involves mixing a positive electrode active material, a conductive agent, and a NaAlCl4 solid electrolyte in a specific weight ratio, followed by grinding and sieving, and then pressing the mixture into a composite positive electrode sheet. NaCl and AlCl3 are mixed in a stoichiometric ratio and subjected to a high-temperature intermelting reaction and mechanical grinding to obtain fine NaAlCl4 solid electrolyte powder. The fine NaAlCl4 solid electrolyte powder is heated to 160°C or higher, and the molten NaAlCl4 solid electrolyte is assembled with the composite positive electrode sheet. After the molten NaAlCl4 solid electrolyte has cooled and solidified, a sodium and / or indium metal negative electrode sheet is heated to a melt, and the other end of the NaAlCl4 solid electrolyte is assembled with the molten negative electrode. Finally, the battery is encapsulated in a battery casing to form an all-solid-state sodium-ion battery. The assembly process of this invention significantly improves the interfacial performance between the positive and negative electrodes and the solid electrolyte.

Description

Technical Field

[0001] This invention relates to the field of solid-state sodium-ion battery technology, specifically to a method for preparing an all-solid-state battery based on NaAlCl4 electrolyte and the all-solid-state battery prepared by this method. Background Technology

[0002] Currently, widely used batteries primarily employ liquid organic electrolytes, which offer advantages such as high ionic conductivity and good wettability. However, their narrow temperature window and safety issues severely limit their application environments. Traditional liquid-ion batteries can no longer meet the ever-increasing energy density and safety requirements of future energy storage systems. Solid-state batteries, assembled using solid electrolytes, can effectively address the safety hazards associated with liquid electrolytes. Solid electrolytes have relatively wide electrochemical and temperature windows, broadening the range of electrode materials and battery operating conditions. Furthermore, solid-state batteries can be stacked in series or parallel to increase capacity. Currently, electrolytes used in all-solid-state batteries mainly include polymer electrolytes, inorganic sulfide solid electrolytes, oxide solid electrolytes, and halide electrolytes. Among these, halide solid electrolytes are a newly developed type of solid electrolyte in recent years, exhibiting high lithium-ion conductivity and advantages in air stability, suggesting a broader application prospect.

[0003] Besides selecting suitable electrolytes and electrode materials for matching, improving electrode and battery fabrication techniques is also crucial for enhancing the high energy density and reliability of batteries. Currently, a key factor hindering the development of solid-state batteries is the poor interfacial compatibility between the positive and negative electrodes / solid electrolyte, resulting in high interfacial impedance and affecting the electrochemical performance of all-solid-state batteries. Therefore, it is necessary to provide an improved solid-state battery fabrication method and related solid-state batteries to address the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing an all-solid-state battery based on NaAlCl4 solid electrolyte and the all-solid-state battery itself, aiming to solve the problem of poor contact at the positive and negative electrode / solid electrolyte interface in the existing all-solid-state battery preparation process, thereby improving the energy density of the solid-state battery and its cycle stability.

[0005] To achieve the above objectives, the present invention proposes a method for preparing an all-solid-state battery, comprising the following steps:

[0006] (1) The positive electrode active material, conductive agent and NaAlCl4 solid electrolyte are mixed in a weight ratio, ground and sieved, and then pressed into a tablet to obtain a composite positive electrode sheet.

[0007] (2) NaCl and AlCl3 were mixed in stoichiometric ratio and then subjected to high-temperature mutual melting reaction and mechanical grinding to obtain NaAlCl4 solid electrolyte powder;

[0008] (3) Cut sodium and / or indium metal into negative electrode sheets of a predetermined diameter;

[0009] (4) Heat the fine NaAlCl4 solid electrolyte powder to 160°C or above in a heating furnace, assemble the molten fine NaAlCl4 solid electrolyte with the composite positive electrode, and after the molten NaAlCl4 solid electrolyte cools and solidifies, heat the negative electrode to melt in a heating furnace, assemble the other end of the NaAlCl4 solid electrolyte with the molten negative electrode, and finally encapsulate it with a battery casing to form an all-solid-state sodium-ion battery.

[0010] All steps (1)-(3) are performed in a protective gas atmosphere.

[0011] Preferably, in step (1), the positive electrode active material is at least one of NaCoO2, Na2MnO4, NaFePO4, Na3V2(PO4)3, and Na4Fe3(PO4)2P2O7; the conductive agent includes at least one of Super P, Ketjen Black, acetylene black, graphene, carbon nanotubes, and carbon nanofibers.

[0012] Preferably, in step (1), the weight ratio of the positive electrode active material, the conductive agent, and the NaAlCl4 solid electrolyte is:

[0013] Positive electrode active material: 60%-80%;

[0014] Conductive agent: 5%-20%;

[0015] NaAlCl4 solid electrolyte: 15%-35%.

[0016] Preferably, in step (2), NaCl and AlCl3 are mixed at a stoichiometric ratio of 1-1.2:1 and then subjected to a high-temperature intermelting reaction in a bottom-blown furnace. After the reaction is completed, the mixture is rapidly cooled to 160℃-180℃, filtered to separate the supernatant, and after the supernatant cools naturally, it is mechanically ground to obtain fine NaAlCl4 solid electrolyte powder.

[0017] Preferably, in step (2), the bottom-blown furnace heating temperature is 800-850℃ and the heating time is 2-8 hours.

[0018] Preferably, in step (2), the ball milling speed of the mechanical ball mill is 200-1000 rpm, and the ball milling time is 2-20 hours.

[0019] Preferably, in step (4), the method of applying pressure to the battery assembly includes one or more of powder hot pressing and powder cold isostatic pressing using a powder forming press; the pressure is 100-700 MPa.

[0020] To achieve the above objectives, the all-solid-state battery proposed in this invention is prepared by any of the methods described above.

[0021] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0022] (1) The all-solid-state battery prepared by the present invention has improved interface contact between the composite positive electrode layer / negative electrode and the solid electrolyte layer, which greatly improves the electrochemical performance and working stability of the all-solid-state battery.

[0023] (2) The preparation method of the all-solid-state battery disclosed in this invention has a simple process flow, does not use organic solvents, and is environmentally friendly.

[0024] (3) The preparation method of the present invention has the advantage of large-scale production. Attached Figure Description

[0025] Figure 1 The diagram shows the charge / discharge specific capacity and coulombic efficiency of the all-solid-state sodium-ion battery prepared in Example 1. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Example 1

[0027] (1) The positive electrode active material, conductive agent and NaAlCl4 solid electrolyte are mixed in weight ratio, ground and sieved, and then pressed into a composite positive electrode sheet; specifically, 100 g is the total mass of the composite positive electrode, in which the positive electrode active material: conductive agent: NaAlCl4 solid electrolyte = 75:3:22. After grinding for 15 minutes, the composite positive electrode powder is obtained and pressed into a 10 mm composite positive electrode sheet by a press.

[0028] (2) Weigh NaCl:AlCl3 at a stoichiometric ratio of 1:1, place it in a bottom-blown furnace and heat at 850°C for 4 hours. When rapidly cooled to 165°C, take the upper clear liquid, cool it to room temperature, place it in a ball mill jar, and ball mill at 500 rpm for 4 hours at a material-to-ball ratio of 1:40 to obtain fine NaAlCl4 solid electrolyte powder.

[0029] (3) Cut the sodium metal into negative electrode sheets with a diameter of 10 mm using a cutting knife.

[0030] (4) The composite positive electrode sheet is preheated in a heating furnace, and then the fine NaAlCl4 solid electrolyte powder is heated to 170°C and placed on the positive electrode sheet. After it cools down, the metallic sodium is heated to 100°C in a heating furnace and placed on the other side of the NaAlCl4 solid electrolyte. The battery is then encapsulated with a battery casing to form an all-solid-state sodium-ion battery. The battery assembly pressure is 100 MPa.

[0031] from Figure 1 It can be seen that within the indicated cycle, the charge-discharge specific capacity overlap is high, the coulombic efficiency remains above 99%, and the battery exhibits good electrochemical performance. Example 2

[0032] (1) The positive electrode active material, conductive agent and NaAlCl4 solid electrolyte are mixed in weight ratio, ground and sieved, and then pressed into a composite positive electrode sheet; specifically, 100 g is the total mass of the composite positive electrode, in which the positive electrode active material: conductive agent: NaAlCl4 halide electrolyte = 78: 2: 20. After grinding for 15 minutes, the composite positive electrode powder is obtained and pressed into a 10 mm composite positive electrode sheet by a press.

[0033] (2) Weigh NaCl:AlCl3 at a stoichiometric ratio of 1.1:1, heat it in a bottom-blown furnace at 850°C for 4 hours, and then rapidly cool it to 165°C. Take the upper clear liquid, cool it to room temperature, and place it in a ball mill jar. Ball mill it at 500 rpm for 5 hours at a material-to-ball ratio of 1:30 to obtain fine NaAlCl4 solid electrolyte powder.

[0034] (3) Cut the indium metal into negative electrode sheets with a diameter of 10 mm using a cutting knife.

[0035] (4) The composite positive electrode sheet is preheated in a heating furnace, and then the fine NaAlCl4 solid electrolyte powder is heated to 170°C and placed on the positive electrode sheet. After it cools down, the metal indium is heated to 160°C in a heating furnace and placed on the other side of the NaAlCl4 solid electrolyte. The battery is then encapsulated with a battery casing to form an all-solid-state sodium-ion battery. The battery assembly pressure is 100 MPa.

[0036] 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 an all-solid-state battery, characterized in that, The method includes the following steps: (1) The positive electrode active material, conductive agent and NaAlCl4 solid electrolyte are mixed in a weight ratio, ground and sieved, and then pressed into a tablet to obtain a composite positive electrode sheet. (2) NaCl and AlCl3 are mixed at a stoichiometric ratio of 1-1.2:1 and then subjected to high-temperature mutual melting reaction and mechanical grinding to obtain fine NaAlCl4 solid electrolyte powder; (3) Cut sodium and / or indium metal into negative electrode sheets of a predetermined diameter; (4) Heat the fine NaAlCl4 solid electrolyte powder to 160°C or above in a heating furnace, assemble the molten NaAlCl4 solid electrolyte with the composite positive electrode, and after the molten NaAlCl4 solid electrolyte cools and solidifies, heat the negative electrode to melt in a heating furnace, assemble the other end of the NaAlCl4 solid electrolyte with the molten negative electrode, and finally encapsulate it with a battery casing to form an all-solid-state sodium-ion battery. All steps (1)-(3) are performed in a protective gas atmosphere.

2. The method for preparing an all-solid-state battery according to claim 1, characterized in that, In step (1), the positive electrode active material is at least one of NaCoO2, Na2MnO4, NaFePO4, Na3V2(PO4)3, and Na4Fe3(PO4)2P2O7; the conductive agent includes at least one of Super P, Ketjen Black, acetylene black, graphene, carbon nanotubes, and carbon nanofibers.

3. The method for preparing an all-solid-state battery according to claim 1, characterized in that, In step (1), the weight ratio of the positive electrode active material, the conductive agent, and the NaAlCl4 solid electrolyte is as follows: Positive electrode active material: 60%-80%; Conductive agent: 5%-20%; NaAlCl4 solid electrolyte: 15%-35%.

4. The method for preparing an all-solid-state battery according to claim 1, characterized in that, In step (2), NaCl and AlCl3 are mixed at a stoichiometric ratio of 1-1.2:1 and then subjected to a high-temperature intermelting reaction in a bottom-blown furnace. After the reaction is completed, the mixture is rapidly cooled to 160℃-180℃, filtered to separate the supernatant, and after the supernatant cools naturally, it is mechanically ground to obtain fine NaAlCl4 solid electrolyte powder.

5. The method for preparing an all-solid-state battery according to claim 4, characterized in that, In step (2), the bottom blowing furnace heating temperature is 800-850℃ and the heating time is 2-8 hours.

6. The method for preparing an all-solid-state battery according to claim 1, characterized in that, In step (2), the ball milling speed of the mechanical ball mill is 200-1000 rpm, and the ball milling time is 2-20 hours.

7. The method for preparing an all-solid-state battery according to claim 1, characterized in that, In step (4), the method of applying pressure to the battery assembly includes one or more of the following: hot pressing of powder and cold isostatic pressing of powder using a powder forming press; the pressure is 100-700 MPa.

8. An all-solid-state battery, characterized in that, The battery is prepared by the method described in any one of claims 1-7.

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