A method for preparing a sodium ion composite solid-state electrolyte

Abstract

The application relates to the technical field of solid electrolytes, in particular to a preparation method of a sodium ion composite solid electrolyte, which comprises the following steps: S1, under an inert gas atmosphere, Na3PS4 and a composite agent are respectively added into an airflow pulverizer through upper and lower cavities of the airflow pulverizer at room temperature, airflow impact dispersion is carried out, uniform dispersion is realized, and a mixture is obtained, wherein the composite agent is PTFE or PEO; and S2, the mixture prepared in the step S1 is subjected to tabletting treatment, and a composite solid electrolyte is obtained. The preparation method improves the problems of uneven dispersion and agglomeration of the composite electrolyte prepared by a conventional solid phase method, avoids the use of a large amount of organic solvents in the preparation process of a liquid phase method, and has the advantages of poor environmental protection and low ionic conductivity of the composite electrolyte.

Description

Technical Field

[0001] This invention relates to a method for preparing a sodium ion composite solid electrolyte, belonging to the field of solid electrolyte technology. Background Technology

[0002] Currently, sulfide solid electrolytes have become a research hotspot in all-solid-state batteries due to their excellent machinability and ionic conductivity comparable to liquid electrolytes.

[0003] Na3PS4 is a common solid electrolyte with excellent electronic conductivity, but its high brittleness and poor machinability severely hinder its application in sodium-ion batteries. To improve the inherent brittleness of Na3PS4, researchers typically enhance the flexibility of sodium-ion solid electrolytes by using composite polymer electrolytes or binders.

[0004] Patent application CN113363570A discloses the preparation of Li using a mechanical ball milling method. 5.4 PS 4.4 Cl 1.6 The method involves preparing a PTFE composite solid electrolyte, but the resulting composite solid electrolyte cannot be used directly and requires further coating with an aluminum oxide-containing modification layer before it can be used normally. Patent application CN111628213A discloses a liquid-phase method for preparing an organic / inorganic composite electrolyte membrane, but this method requires a large amount of organic solvent, resulting in poor environmental friendliness. Furthermore, due to the low ionic conductivity of PTFE, the ionic conductivity of the prepared composite electrolyte will also be reduced. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for preparing sodium ion composite solid electrolytes. This method improves upon the problems of uneven dispersion and agglomeration in composite electrolytes prepared by conventional solid-phase methods, while avoiding the disadvantages of liquid-phase methods, such as the use of large amounts of organic solvents, poor environmental performance, and low ionic conductivity of the composite electrolytes.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing a sodium ion composite solid electrolyte, wherein the preparation method is as follows:

[0007] S1. Under an inert gas atmosphere and at room temperature, Na3PS4 and the composite agent are added to the air jet mill through the upper and lower chambers respectively, and dispersed by air jet impact to obtain a uniformly dispersed mixture.

[0008] S2. The mixture prepared in step S1 is compressed into tablets to obtain a composite solid electrolyte.

[0009] Furthermore, in step S1, the composite agent is PTFE or PEO.

[0010] Furthermore, the molecular weight of the composite agent is 10. 5 ~10 6 .

[0011] Furthermore, in step S1, the amount of Na3PS4 used is 99~99.8 parts by weight, and the amount of the composite agent is 0.2~1.0 parts.

[0012] Furthermore, in step S1, the airflow magnitude in the upper chamber of the airflow pulverizer is 0.2~0.8MPa, and the airflow magnitude in the lower chamber of the airflow pulverizer is 0~0.6MPa. The airflow in the lower chamber of the airflow pulverizer must be at least 0.2MPa less than the airflow in the upper chamber.

[0013] Furthermore, the particle size D50 of the mixture obtained in step S1 is 4.3~5.8μm.

[0014] Furthermore, the tableting pressure in step S2 is 5~15 MPa.

[0015] The beneficial effects of this invention are:

[0016] (1) The method for preparing sodium ion composite solid electrolyte of the present invention achieves uniform composite of sodium ion solid electrolyte by air jet pulverization and rolling film formation, and the conductivity of the composite solid electrolyte can reach 0.71 mS / cm, thus realizing the preparation of uniform composite solid electrolyte by solvent-free method.

[0017] (2) The method for preparing sodium ion composite solid electrolyte of the present invention not only improves the problems of uneven dispersion and agglomeration of composite electrolytes prepared by conventional solid phase method, but also avoids the disadvantages of using a large amount of organic solvents in the liquid phase preparation process, poor environmental protection, and low ionic conductivity of composite solid electrolyte.

[0018] (3) The preparation method of the sodium ion composite solid electrolyte of the present invention adopts a solvent-free dispersion process and uses airflow pulverization and rolling film formation method. The process is simple, the operation is controllable, and it can be mass-produced on a large scale, which has great application prospects.

[0019] (4) The method for preparing sodium ion composite solid electrolyte of the present invention reduces the particle size of solid electrolyte by adjusting the pressure of the upper and lower chambers of the air jet mill, which helps to achieve uniform dispersion and adhesion of the composite agent. Furthermore, the air jet impact crushing of solid electrolyte particles can effectively reduce the amount of binder used and improve the ionic conductivity of the composite electrolyte. Attached Figure Description

[0020] Figure 1 This is a diagram showing the folding and bending of the composite solid electrolyte obtained in Example 1;

[0021] Figure 2 This is a diagram showing the fracture of the solid electrolyte obtained in Comparative Example 8 after folding and bending. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0024] Example 1

[0025] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the upper chamber of the air jet mill, and PTFE was added from the lower chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.2MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 5.1μm.

[0026] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0027] Example 2

[0028] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the lower chamber of the air jet mill, and PTFE was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.4MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.5μm.

[0029] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0030] Example 3

[0031] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10)5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the upper chamber of the air jet mill, and PTFE was added from the lower chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.6MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.3μm.

[0032] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0033] Example 4

[0034] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the lower chamber of the air jet mill, and PTFE was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.6MPa and the pressure in the lower chamber was 0.2MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 5.4μm.

[0035] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0036] Example 5

[0037] S1: Under a nitrogen atmosphere, Na3PS4 and PEO (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the upper chamber of the air jet mill, and PEO was added from the lower chamber of the air jet mill. The pressure in the upper chamber was 0.6MPa and the pressure in the lower chamber was 0.4MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.9μm.

[0038] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0039] Example 6

[0040] S1: Under a nitrogen atmosphere, Na3PS4 and PEO (molecular weight 10) 5 ~10 6Shenzhen Kejing Zhida Technology Co., Ltd.) carried out air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the lower chamber of the air jet mill, and PEO was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.4MPa and the pressure in the lower chamber was 0.2MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 5.6μm.

[0041] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0042] Example 7

[0043] S1: Under a nitrogen atmosphere, Na3PS4 and PEO (molecular weight 10) 5 ~10 6 Shenzhen Kejing Zhida Technology Co., Ltd.) carried out air jet milling with Na3PS4 added from the upper chamber of the air jet mill and PEO added from the lower chamber of the air jet mill. The pressure in the upper chamber was 0.2 MPa and the pressure in the lower chamber was 0 MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 5.8 μm.

[0044] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0045] Example 8

[0046] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.6:0.4. Na3PS4 was added from the lower chamber of the air jet mill, and PTFE was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.6MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.4μm.

[0047] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0048] Example 9

[0049] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6(Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.4:0.6. Na3PS4 was added from the lower chamber of the air jet mill, and PTFE was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.6MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.3μm.

[0050] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0051] Example 10

[0052] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.2:0.8. Na3PS4 was added from the lower chamber of the air jet mill, and PTFE was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.6MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.4μm.

[0053] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0054] Example 11

[0055] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 99.0:1.0. Na3PS4 was added from the lower chamber of the air jet mill, and PTFE was added from the upper chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.6MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 4.4μm.

[0056] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0057] Comparative Example 1

[0058] The difference from Example 1 is that the preparation is carried out by mechanical ball milling, including the following steps:

[0059] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.8:0.2 at 200 rpm for 1 hour to obtain a mixture with a D50 of 6.2 μm. The mixture was then rolled into a film and its ionic conductivity was tested.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that the preparation is carried out by mechanical ball milling, including the following steps:

[0062] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.8:0.2 at 400 rpm for 1 hour to obtain a mixture with a D50 of 5.4 μm. The mixture was then rolled into a film and the ionic conductivity was tested.

[0063] Comparative Example 3

[0064] The difference from Example 1 is that the preparation is carried out by mechanical ball milling, including the following steps:

[0065] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.8:0.2 at 600 rpm for 1 hour to obtain a mixture with a D50 of 5.3 μm. The mixture was then rolled into a film and the ionic conductivity was tested.

[0066] Comparative Example 4

[0067] The difference from Example 8 is that the preparation was carried out using a mechanical ball milling method, including the following steps:

[0068] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.6:0.4 at 400 rpm for 1 hour to obtain a mixture with a D50 of 5.7 μm. The mixture was then rolled into a film and the ionic conductivity was tested.

[0069] Comparative Example 5

[0070] The difference from Example 9 is that the preparation is carried out by mechanical ball milling, including the following steps:

[0071] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.4:0.6 at 400 rpm for 1 hour to obtain a mixture with a D50 of 5.8 μm. The mixture was then rolled into a film and its ionic conductivity was tested.

[0072] Comparative Example 6

[0073] The difference from Example 10 is that the preparation was carried out using a mechanical ball milling method, including the following steps:

[0074] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.2:0.8 at 400 rpm for 1 hour to obtain a mixture with a D50 of 5.9 μm. The mixture was then rolled into a film and its ionic conductivity was tested.

[0075] Comparative Example 7

[0076] The difference from Example 11 is that the preparation was carried out by mechanical ball milling, including the following steps:

[0077] Na3PS4 and PTFE were ball-milled at a mass ratio of 99.0:1.0 at 400 rpm for 1 hour to obtain a mixture with a D50 of 6.5 μm. The mixture was then rolled into a film and its ionic conductivity was tested.

[0078] Comparative Example 8

[0079] The difference from Example 1 is that PTFE was not added, and the following steps were included:

[0080] S1: Na3PS4 was subjected to air jet milling under a nitrogen atmosphere. Na3PS4 was added through the upper chamber at a pressure of 0.8 MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 5.1 μm.

[0081] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0082] Comparative Example 9

[0083] The difference from Example 1 is that the amount of PTFE added is increased, including the following steps:

[0084] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) The mixture was subjected to air jet milling at a mass ratio of 98.8:1.2. Na3PS4 was added from the upper chamber of the air jet mill, and PTFE was added from the lower chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa and the pressure in the lower chamber was 0.2MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 5.1μm.

[0085] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0086] Comparative Example 10

[0087] The difference from Example 1 is that the upper chamber pressure and the lower chamber pressure are the same, and the following steps are included:

[0088] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 Shenzhen Kejing Zhida Technology Co., Ltd.) carried out air jet milling at a mass ratio of 99.8:0.2. Na3PS4 was added from the upper chamber of the air jet mill, and PTFE was added from the lower chamber of the air jet mill. The pressure in the upper chamber was 0.8MPa, and the pressure in the lower chamber was 0.8MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 6.1μm.

[0089] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0090] Comparative Example 11

[0091] The difference from Example 1 is that Na3PS4 and PTFE are added to the air jet mill through a single chamber, including the following steps:

[0092] S1: Under a nitrogen atmosphere, Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 Shenzhen Kejing Zhida Technology Co., Ltd.) carried out air jet milling at a mass ratio of 99.8:0.2. Na3PS4 and PTFE were mixed and added from the upper chamber of the air jet mill at a pressure of 0.8MPa. The powder was collected and stirred evenly to obtain a mixture with a D50 of 6.3μm.

[0093] S2: The mixture prepared in step S1 is compressed into tablets under a pressure of 5~15MPa to obtain a sodium ion composite solid electrolyte, and the ionic conductivity is tested.

[0094] Comparative Example 12

[0095] The difference from Example 1 is that the preparation is carried out using a liquid phase method, including the following steps:

[0096] Na3PS4 and PTFE (molecular weight 10) 5 ~10 6 (Shenzhen Kejing Zhida Technology Co., Ltd.) Pour the mixture into a beaker at a mass ratio of 99.8:0.2, add acetone and mix thoroughly. After the mixture is evenly mixed, coat the mixture, dry it, and test the ionic conductivity and particle size.

[0097] The relevant test data for Examples 1-11 and Comparative Examples 1-12 are shown in Table 1 below:

[0098] Table 1. Relevant test data for Examples 1-11 and Comparative Examples 1-12

[0099]

[0100] According to the data in Table 1, the composite solid electrolyte obtained by the method described in this invention exhibits good ionic conductivity. The opposing pressure difference between the upper and lower chambers in the air jet mill is beneficial for reducing the particle size of the composite electrolyte material. This reduction in particle size promotes denser particle packing of the composite electrolyte, thereby improving ionic conductivity. Furthermore, the uniform addition of the composite agent gives the obtained composite solid electrolyte excellent toughness; it will not break even when bent or folded. Figure 1 As shown.

[0101] The data from Comparative Examples 1-7 show that the composite solid electrolytes obtained using conventional ball milling dispersion techniques have relatively low conductivity. This is because conventional ball milling dispersion techniques tend to cause material agglomeration, leading to larger particle sizes and affecting the dispersion effect of the composite electrolyte, thus reducing its ionic conductivity. Furthermore, the composite solid electrolytes obtained from Comparative Examples 1-7 exhibit relatively poor toughness, showing cracking when bent or folded. This is because the agglomeration of the powder material results in relatively poor mixing uniformity between the composite agent and the conductive agent, thereby affecting the toughness of the composite solid electrolyte.

[0102] In Comparative Example 8, without the addition of a composite agent, the ionic conductivity was relatively high, but the toughness was very poor; it would break even with slight bending or folding. Figure 2 As shown, this will cause great inconvenience to subsequent applications.

[0103] In Comparative Example 9, the amount of composite agent added was increased, and the ionic conductivity of the composite solid electrolyte obtained as a seed was poor. Therefore, using the amount of composite agent added as described in this invention is more conducive to obtaining a composite solid electrolyte of excellent quality.

[0104] In Comparative Example 10, no pressure difference was set between the upper and lower chambers during the air jet milling process, resulting in a relatively poor ionic conductivity of the composite solid electrolyte. In Comparative Example 11, both Na3PS4 and PTFE were added to the air jet mill through the upper chamber during the air jet milling process, and the resulting composite solid electrolyte also had relatively poor ionic conductivity. Therefore, the preparation method described in this invention provides better dispersion of the components, which is more conducive to obtaining a composite solid electrolyte with high toughness and high ionic conductivity.

[0105] Comparative Example 12 uses a conventional liquid-phase method to prepare a composite solid electrolyte. The preparation process uses a large amount of organic solvent, which is not environmentally friendly, and the composite electrolyte has slightly lower ionic conductivity.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing a sodium ion composite solid electrolyte, characterized in that, The preparation method is as follows: S1. Under an inert gas atmosphere and at room temperature, Na3PS4 and the composite agent are added to the air jet mill through the upper and lower chambers respectively, and dispersed by air jet impact to obtain a uniformly dispersed mixture. S2. The mixture prepared in step S1 is compressed into tablets to obtain a composite solid electrolyte; In step S1, the amount of Na3PS4 used is 99~99.8 parts by weight, and the amount of the composite agent is 0.2~1.0 parts; the composite agent is PTFE or PEO. In step S1, the airflow magnitude in the upper chamber of the airflow pulverizer is 0.2~0.8MPa, and the airflow magnitude in the lower chamber of the airflow pulverizer is 0~0.6MPa. The airflow magnitude in the lower chamber of the airflow pulverizer must be at least 0.2MPa less than the airflow magnitude in the upper chamber. The particle size D50 of the mixture obtained in step S1 is 4.3~5.8μm.

2. The method for preparing a sodium ion composite solid electrolyte according to claim 1, characterized in that, The molecular weight of the compound is 10. 5 ~10 6 .

3. The method for preparing a sodium ion composite solid electrolyte according to claim 1, characterized in that, The tableting pressure in step S2 is 5~15MPa.

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