High-ionic-conductivity solid electrolyte, preparation method thereof and solid-state battery

Abstract

The invention relates to the technical field of solid-state electrolytes, and discloses a high-ionic-conductivity solid-state electrolyte, a preparation method thereof and a solid-state battery. The preparation method comprises the following steps: mixing lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide and boron nitride in an inert atmosphere to obtain a mixture; carrying out ball milling on the mixture to obtain precursor powder; and sintering the precursor powder, and dispersing the sintered precursor powder to obtain the high-ionic-conductivity solid electrolyte. The boron element, the nitrogen element and the oxygen element are introduced into a lithium phosphorus sulfur chlorine system as doping elements, lattice parameters of LPSC are changed through the boron element, the rotation rate of a PS4 / BS4 tetrahedron is enhanced, and a lithium ion diffusion channel is optimized, so that the lithium ion transition activation energy of the electrolyte is reduced, the migration rate of lithium ions is increased, and the performance of the electrolyte is improved. Therefore, the solid electrolyte has high ionic conductivity. The introduced nitrogen element and oxygen element can interact with atoms such as sulfur and phosphorus, the electron cloud distribution of anion groups is adjusted, the interaction energy of lithium ions and the anion groups is reduced, the lithium ion transmission performance is further improved, and the electrochemical stability of the anion framework is enhanced. This makes it possible to increase the energy density of an all-solid-state battery when used in a solid-state battery.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and particularly to a solid electrolyte with high ionic conductivity, a preparation method thereof, and a solid-state battery. Background Art

[0002] Lithium phosphorus sulfur chloride (Li6PS5Cl, LPSC), as an important sulfide solid electrolyte system, plays a key role in the development of all-solid-state batteries.

[0003] LPSC has a unique crystal structure, in which phosphorus, sulfur, and chlorine atoms form a complex anion framework through covalent bonds. Lithium ions diffuse and transport in this framework, and it usually exhibits high ionic conductivity at room temperature, which can meet the requirements of all-solid-state battery applications. However, there are still some limiting factors in its ion transport mechanism. For example, grain boundary resistance, high binding energy, and local structural defects may hinder the rapid migration of lithium ions, resulting in low ionic conductivity and affecting the overall performance of the battery.

[0004] Therefore, the existing technology still needs to be further improved and enhanced. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a solid electrolyte with high ionic conductivity, a preparation method thereof, and a solid-state battery, aiming to improve the performance of LPSC-based sulfide solid electrolytes by doping boron, oxygen, and nitrogen elements.

[0006] The above object of the present invention is achieved by the following technical solutions: A preparation method of a solid electrolyte with high ionic conductivity, comprising the following steps:

[0007] Under an inert atmosphere condition, mix lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide, and boron nitride to obtain a mixed material;

[0008] Ball mill the mixed material to obtain a precursor powder;

[0009] Sinter the precursor powder, and disperse the sintered precursor powder to obtain a solid electrolyte with high ionic conductivity.

[0010] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the purpose and beneficial effects of the present invention can be better achieved.

[0011] As a preferred technical solution, in the preparation method of the solid electrolyte with high ionic conductivity, the molar ratio of lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide, and boron nitride is 2:1:0.1:0.5:0.1.

[0012] As a preferred technical solution, in the preparation method of the high ionic conductivity solid electrolyte, the chemical formula of the high ionic conductivity solid electrolyte is Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 Cl.

[0013] As a preferred technical solution, in the preparation method of the high ionic conductivity solid electrolyte, the ball-to-material ratio of the ball milling is 35 - 40:1.

[0014] As a preferred technical solution, in the preparation method of the high ionic conductivity solid electrolyte, the sintering includes: loading the precursor powder into a glass crucible and placing it in a muffle furnace for sintering. The sintering temperature is 530 - 580 °C, and the sintering heating rate is 3 - 5 °C / min.

[0015] As a preferred technical solution, in the preparation method of the high ionic conductivity solid electrolyte, the particle size of the high ionic conductivity solid electrolyte is 5 - 12 μm.

[0016] As a preferred technical solution, in the preparation method of the high ionic conductivity solid electrolyte, under the condition of an inert atmosphere, the oxygen content < 1 ppm and the water content < 0.01 ppm.

[0017] As a preferred technical solution, in the preparation method of the high ionic conductivity solid electrolyte, the conductivity of the high ionic conductivity solid electrolyte is 10.5 mS / cm.

[0018] In the second aspect, a high ionic conductivity solid electrolyte is provided, which is prepared by using the above-mentioned preparation method.

[0019] In the third aspect, a solid-state battery is provided, which includes an electrode and an electrolyte, and the electrolyte is the above-mentioned high ionic conductivity solid electrolyte.

[0020] Beneficial effects: Compared with the prior art, the present invention introduces boron, nitrogen, and oxygen elements as doping elements into the lithium phosphorus sulfur chlorine system. By changing the lattice parameters of LPSC, enhancing the rotation rate of the PS4 / BS4 tetrahedron, and optimizing the lithium ion diffusion channels with boron element, the activation energy of lithium ion transition in the electrolyte is reduced, and the migration rate of lithium ions is increased, thereby enabling the solid electrolyte to have high ionic conductivity. The introduction of nitrogen and oxygen elements can interact with atoms such as sulfur and phosphorus, regulate the electron cloud distribution of the anion group, reduce the interaction energy between lithium ions and the anion group, and further improve the lithium ion transport performance and enhance the electrochemical stability of the anion framework. This enables it to improve the energy density of all-solid-state batteries when used in solid-state batteries. Description of the Drawings

[0021] Figure 1 is a schematic flow chart of a method for preparing a solid electrolyte with high ionic conductivity provided by the present invention;

[0022] Figure 2 is the Nyquist diagram of the solid electrolyte with high ionic conductivity provided by the present invention. Detailed Embodiments

[0023] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0025] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise clearly specified in the context, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0027] As Figure 1 described, a method for preparing a high ionic conductivity solid electrolyte provided by the present invention includes the following steps:

[0028] S10. Under an inert atmosphere condition, mix lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide, and boron nitride to obtain a mixed material.

[0029] Specifically, the inert atmosphere can be an inert gas such as nitrogen or argon. Under the inert atmosphere condition, the oxygen content is <1 ppm, and the water content is <0.01 ppm, that is, it is required to strictly control the water and oxygen content in the operating environment to prevent the raw materials from being oxidized and affecting the performance of the product. The operation can be carried out in a glove box. Accurately weigh lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide, and boron nitride according to the ratio, and mix them evenly to obtain a mixed material.

[0030] S20. Ball mill the mixed material to obtain precursor powder.

[0031] Specifically, the above-mentioned weighed materials can be mixed and then ball milled using a high-energy ball mill at a rotation speed of 500 rpm for 24 h. The ball milling beads used are a mixture of three types of ball milling beads with diameters of 10 mm, 5 mm, and 3 mm, and the ball-to-material ratio is 40:1. The ball milling program is set to rotate for 15 min and rest for 5 min, with forward and reverse rotations alternating. After ball milling, precursor powder is obtained.

[0032] S30. Sinter the precursor powder, and disperse the sintered precursor powder to obtain a high ionic conductivity solid electrolyte.

[0033] Specifically, the precursor powder obtained after ball milling can be loaded into a glass crucible and placed in a muffle furnace for sintering. The sintering program is set to heat up to 550 °C at a rate of 5 °C / min and hold for 11 h, and then naturally cooled to room temperature. After taking out the sintered powder, it is ground into a uniform powder using a mortar to obtain the solid electrolyte.

[0034] Based on the same inventive concept, the present invention also provides a solid electrolyte prepared by the above preparation method. Since the preparation method has been explained in detail above, it will not be elaborated here. For the solid electrolyte prepared by the above preparation method, B, N, and O are introduced as doping elements into the LPSC system, which plays a positive role in the ionic conductivity of the electrolyte. B has a unique electronic structure and a small ionic radius, which can change the lattice parameters of LPSC, enhance the rotation rate of the PS4 / BS4 tetrahedron, optimize the lithium ion diffusion channel, thereby reducing the activation energy of lithium ion transition in the electrolyte, increasing the migration rate of lithium ions, and thus improving the ionic conductivity. The introduction of N and O atoms can interact with atoms such as sulfur and phosphorus, adjust the electron cloud distribution of the anion group, reduce the interaction energy between lithium ions and the anion group, thereby improving the lithium ion transport performance and enhancing the electrochemical stability of the anion framework. After the introduction of N / O atoms, the chemical properties of the electrolyte / electrode interface can also be changed, suppressing side reactions and protecting the structural integrity of the electrode material, thereby prolonging the cycle life of the battery, which is of great significance for matching high-voltage cathode materials and improving the energy density of all-solid-state batteries.

[0035] Based on the same inventive concept, the present invention also provides a solid-state battery, the electrolyte of which is the electrolyte described above in the present invention. In this solid-state battery, since N and O are introduced into the electrolyte and can interact with atoms such as sulfur and phosphorus, adjusting the electron cloud distribution of the anion group and reducing the interaction energy between lithium ions and the anion group, thereby improving the lithium ion transport performance and enhancing the electrochemical stability of the anion framework. After the introduction of N / O atoms, the chemical properties of the electrolyte / electrode interface can also be changed, suppressing side reactions and protecting the structural integrity of the electrode material, making the solid-state battery have a good cycle life.

[0036] The following specific examples are used to further explain the preparation method of the high ionic conductivity solid electrolyte provided by the present invention. It should be particularly noted that all operation processes in the following examples are carried out in a glove box filled with argon (O2 < 1 ppm, H2O < 0.01 ppm), and the water and oxygen values need to be strictly controlled in the preparation environment.

[0037] Example 1

[0038] Accurately weigh Li2S, LiCl, Li2O, P2S5, and BN according to a molar ratio of 2:1:0.1:0.5:0.1, and then mix them evenly with a mortar first.

[0039] Ball mill the above evenly mixed powder for 20 h at a rotational speed of 550 rpm using a high-energy ball mill. The ball-milling beads used are a mixture of three diameters of 10 mm, 5 mm, and 3 mm, the ball-to-material ratio is 35:1, and the ball-milling program is set to rotate for 15 min and rest for 5 min, with forward and reverse rotations alternating.

[0040] Load the ball-milled powder into a glass crucible and place it in a muffle furnace for sintering. The sintering program is set to heat up to 530 °C at a rate of 3 °C / min and hold for 11 h, and then naturally cool to room temperature.

[0041] After taking out the sintered powder, grind it into a uniform powder with a mortar to obtain the Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 BPSNOCl solid electrolyte.

[0042] Example 2

[0043] Accurately weigh Li2S, LiCl, Li2O, P2S5, and BN according to a molar ratio of 2:1:0.1:0.5:0.1, and then mix them evenly with a mortar first.

[0044] Ball mill the above evenly mixed powder for 24 h at a rotational speed of 500 rpm using a high-energy ball mill. The ball-milling beads used are a mixture of three diameters of 10 mm, 5 mm, and 3 mm, the ball-to-material ratio is 40:1, and the ball-milling program is set to rotate for 15 min and rest for 5 min, with forward and reverse rotations alternating.

[0045] Load the ball-milled powder into a glass crucible and place it in a muffle furnace for sintering. The sintering program is set to heat up to 550 °C at a rate of 4 °C / min and hold for 11 h, and then naturally cool to room temperature.

[0046] After taking out the sintered powder, grind it into a uniform powder with a mortar to obtain the Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 BPSNOCl solid electrolyte.

[0047] Example 3

[0048] Accurately weigh Li2S, LiCl, Li2O, P2S5, and BN according to a molar ratio of 2:1:0.1:0.5:0.1, and then mix them evenly with a mortar first.

[0049] The above-mentioned uniformly mixed powder was ball-milled using a high-energy ball mill at a rotational speed of 500 rpm for 24 h. The ball-milling beads used were a mixture of three types of beads with diameters of 10 mm, 5 mm, and 3 mm, the ball-to-powder ratio was 40:1, and the ball-milling program was set to rotate for 15 min and rest for 5 min, with forward and reverse rotations alternating.

[0050] The ball-milled powder was loaded into a glass crucible and placed in a muffle furnace for sintering. The sintering program was set to heat up to 580 °C at a rate of 5 °C / min, hold for 11 h, and then cool naturally to room temperature.

[0051] After taking out the sintered powder, it was ground into a uniform powder using a mortar, and thus the Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 BPSNOCl solid electrolyte was obtained.

[0052] 100 mg of the prepared Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 Cl (LBPSNOC) electrolyte was weighed and poured into a PEEK-lined mold battery with an inner diameter of 10 mm, and a uniaxial pressure of 3 tons was applied for cold pressing for 3 min. Then the solid-state battery was tightened, and EIS (10 mV, 7 MHz - 100 MHz) was measured at room temperature. The ionic conductivity of the electrolyte was calculated according to formula (1):

[0053]

[0054] In the formula, L is the thickness of the electrolyte after cold pressing, R is the measured bulk impedance of the electrolyte, and S is the area of the electrolyte.

[0055] The ionic conductivity of the prepared solid electrolyte was calculated to be 10.5 mS / cm through the impedance spectrum actually measured, the electrolyte thickness, and the area, as Figure 2 shown.

[0056] In summary, the present invention provides a method for preparing a solid electrolyte with high ionic conductivity, including: accurately weighing Li2S, LiCl, Li2O, P2S5, and BN according to a molar ratio of 2:1:0.1:0.5:0.1 and mixing them, and first grinding them thoroughly and evenly using a mortar. Then, ball-milling was carried out using a high-energy ball mill. The ball-milled powder was loaded into a glass crucible and placed in a muffle furnace for sintering. After taking out the sintered powder, it was ground into a uniform powder using a mortar, and thus the Li 5.2 B 0.1 PS 4.5 N0.1 O 0.1 Cl solid electrolyte. Introducing B, N, and O as doping elements into the LPSC system plays a positive role in the ionic conductivity of the electrolyte. B has a unique electronic structure and a small ionic radius, which can change the lattice parameters of LPSC, enhance the rotation rate of the PS4 / BS4 tetrahedron, optimize the lithium-ion diffusion channels, thereby reducing the activation energy of lithium-ion transition in the electrolyte, increasing the migration rate of lithium ions, and thus improving the ionic conductivity.

[0057] At the same time, the solid electrolyte provided by the present invention is used to prepare a solid-state battery. Since the introduction of N and O atoms in the solid electrolyte can interact with atoms such as sulfur and phosphorus, adjust the electron cloud distribution of the anion group, reduce the interaction energy between lithium ions and the anion group, and then improve the lithium-ion transport performance and enhance the electrochemical stability of the anion framework. After the introduction of N / O atoms, it can also change the chemical properties of the electrolyte-electrode interface, inhibit side reactions, protect the structural integrity of the electrode material, and thus extend the cycle life of the battery, which is of great significance for matching high-voltage cathode materials and improving the energy density of all-solid-state batteries.

[0058] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A preparation method of a solid electrolyte with high ionic conductivity, characterized in that It includes the following steps: Under the condition of an inert atmosphere, mix lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide and boron nitride to obtain a mixture; Ball-mill the mixture to obtain precursor powder; Sinter the precursor powder, and disperse the sintered precursor powder to obtain a solid electrolyte with high ionic conductivity.

2. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that, The molar ratio of lithium sulfide, lithium chloride, lithium oxide, phosphorus pentasulfide and boron nitride is 2:1:0.1:0.5:0.

1.

3. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that, The chemical formula of the high ionic conductivity solid electrolyte is Li 5.2 B 0.1 PS 4.5 N 0.1 O 0.1 Cl.

4. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that, The ball-to-material ratio of the ball-milling is 35-40:

1.

5. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that, The sintering includes: loading the precursor powder into a glass crucible, placing it in a muffle furnace for sintering, the sintering temperature is 530-580 °C, and the sintering heating rate is 3-5 °C / min.

6. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that The particle size of the solid electrolyte with high ionic conductivity is 5-12 μm.

7. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that, Under the condition of an inert atmosphere, the oxygen content is <1 ppm and the water content is <0.01 ppm.

8. The preparation method of the high ionic conductivity solid electrolyte according to claim 1, characterized in that, The conductivity of the solid electrolyte with high ionic conductivity is 10.5 mS / cm.

9. A solid electrolyte with high ionic conductivity, characterized in that, It is prepared by using the preparation method described in any one of claims 1-8.

10. A solid-state battery, characterized in that, It includes an electrode and an electrolyte, and the electrolyte is the solid electrolyte with high ionic conductivity described in claim 9.

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