Surface-modified sulfide solid electrolyte material, preparation method and device, and application

Abstract

The application discloses a surface-modified sulfide solid electrolyte material, a preparation method and device and application, wherein the surface-modified sulfide solid electrolyte material comprises a sulfide solid electrolyte material and a protective film on the surface of the sulfide solid electrolyte material; the protective film is obtained by modifying the sulfide solid electrolyte material by a dry gas containing carbon dioxide; and the composition of the protective film comprises a carbonate salt; the surface-modified sulfide solid electrolyte material provided by the application greatly improves the chemical stability of the sulfide solid electrolyte to air, an alkali metal negative electrode and a high-voltage oxide positive electrode material, avoids generating a large amount of inert by-products in the battery operation process, and at the same time, the high ion conductivity of the sulfide solid electrolyte itself is retained to the greatest extent, the performance of a full solid-state battery is greatly improved, the surface-modified sulfide solid electrolyte material is expected to be applied to a next-generation high-specific-energy battery, and the surface-modified sulfide solid electrolyte material has great practical value.

Description

Technical Field

[0001] This invention relates to the field of secondary battery materials technology, and in particular to a surface-modified sulfide solid electrolyte material, its preparation method and apparatus, and its applications. Background Technology

[0002] Currently, commercially available rechargeable batteries primarily use liquid organic electrolytes as the medium for the transport of cations and anions between the positive and negative electrodes. These liquid electrolytes typically have poor thermal stability, posing safety hazards such as leakage and combustion. Therefore, to address the potential safety issues of current rechargeable batteries and further improve battery energy density, researchers have begun to use non-flammable solid electrolytes to replace traditional organic electrolytes.

[0003] Solid electrolytes are mainly classified into polymer electrolytes and inorganic solid electrolytes. Current research indicates that sulfide electrolytes exhibit extremely high ionic conductivity, comparable to liquid electrolytes, and possess good mechanical properties and are easy to process, making them the most practically valuable solid electrolyte materials. However, most sulfide electrolytes are unstable in air and have poor chemical stability. They readily react with high-voltage oxide cathode materials and alkali metal (lithium, sodium, potassium) anodes, producing inert byproducts that hinder ion and electron transport, thus limiting their application in high-energy-density batteries.

[0004] To improve the stability of sulfide solid electrolyte materials against air and against high-voltage oxide cathode materials and alkali metal (lithium, sodium, potassium) anodes, this invention provides a method for preparing surface-modified sulfide solid electrolytes. This method utilizes carbon dioxide gas to react in situ on the surface of the sulfide solid electrolyte to form a protective film. The resulting surface-modified sulfide solid electrolyte exhibits significantly improved chemical stability while retaining the high ionic conductivity of the sulfide solid electrolyte material to the greatest extent possible. This method is simple, efficient, and easily scalable for mass production. Summary of the Invention

[0005] This invention provides a surface-modified sulfide solid electrolyte material, its preparation method and apparatus, and its application. The purpose of this invention is to overcome the defects of the prior art and provide a sulfide solid electrolyte that is stable for air and alkali metal (lithium, sodium, potassium) negative electrodes and high-voltage oxide positive electrode materials.

[0006] To achieve the above objectives, the technical solution adopted in this invention is as follows: Surface modification of the sulfide solid electrolyte material is performed by using carbon dioxide gas to form a protective film in situ on the surface of the sulfide solid electrolyte material. Carbon dioxide can combine with alkali metal elements in the sulfide solid electrolyte to form a carbonate protective layer, while simultaneously creating vacancies in the original sulfide solid electrolyte lattice. By controlling the degree of surface reaction, the high ionic conductivity of the sulfide solid electrolyte itself can be largely preserved.

[0007] In a first aspect, embodiments of the present invention provide a surface-modified sulfide solid electrolyte material, the surface-modified sulfide solid electrolyte material comprising a sulfide solid electrolyte material and a protective film on the surface of the sulfide solid electrolyte material;

[0008] The protective film is obtained by modifying the sulfide solid electrolyte material with a dry gas containing carbon dioxide; the components of the protective film include carbonates.

[0009] Preferably, in the surface-modified sulfide solid electrolyte material according to claim 1, the sulfide solid electrolyte material comprises: Li 10 GeP2S 12 Li 6.6 P 0.4 Ge 0.6 S6I, Li7GePS8, Li7Ge3PS 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 SiP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li4SnS4, Li 10 SnP2S 12 Li₂SnS₃, Li₃PS₄, Li₇P₃S 11 , Li7PS6, Li2S·GeS2, Li2S·P2S5, Li2S·P2S5·LiI, Li2S·As2S5·SnS2, Li7P2S8I, Li4PS4I, Li7P 2.9 S 10.85 Mo 0.01 , Li2CuPS4, (Li2S)9(P2S5)3(Ni3S2), Li7P 2.9 Mn 0.1 S 10.7 I 0.3 Li 10.35 Sn 0.27 Si 1.08 P 1.65 S 12 , Na3PS4, Na3SbS4, Na3SnS4, Na 11 Sn2PS 12 Na 3.75 Sn 0.75 Sb 0.25 S4, Na 3.1 Sn 0.1 P 0.9S4, Na4SiS4, Na 2.375 PS 3.375 Cl 0.625 Na3P 0.62 As 0.38 S4, Na3PSe4, Na 10 GeS2P 12 Na 10 SnS2P 12 Na 10 SiS2P 12 One or more of Na2S, K2S, and K3PS4.

[0010] Preferably, in the surface-modified sulfide solid electrolyte material according to claim 1, the thickness of the protective film is between 1 nm and 500 nm.

[0011] In a second aspect, a method for preparing the surface-modified sulfide solid electrolyte material described in the first aspect above, the method comprising:

[0012] A sulfide solid electrolyte material is placed in a reaction apparatus, the temperature of which is set between 0°C and 500°C, and a dry gas containing carbon dioxide is introduced to form a protective film on the surface of the sulfide solid electrolyte material. The protective film is composed of carbonates. The surface-modified sulfide solid electrolyte material includes the sulfide solid electrolyte material and the protective film on the surface of the sulfide solid electrolyte material.

[0013] The flow rate of the carbon dioxide-containing dry gas is 10 cm. 3 / min-5000cm 3 The rate is between 1 minute and 72 hours, during which the dry gas containing carbon dioxide is introduced.

[0014] The sulfide solid electrolyte material includes: Li 10 GeP2S 12 Li 6.6 P 0.4 Ge 0.6 S6I, Li7GePS8, Li7Ge3PS 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 SiP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li4SnS4, Li 10 SnP2S 12Li₂SnS₃, Li₃PS₄, Li₇P₃S 11 , Li7PS6, Li2S·GeS2, Li2S·P2S5, Li2S·P2S5·LiI, Li2S·As2S5·SnS2, Li7P2S8I, Li4PS4I, Li7P 2.9 S 10.85 Mo 0.01 , Li2CuPS4, (Li2S)9(P2S5)3(Ni3S2), Li7P 2.9 Mn 0.1 S 10.7 I 0.3 Li 10.35 Sn 0.27 Si 1.08 P 1.65 S 12 , Na3PS4, Na3SbS4, Na3SnS4, Na 11 Sn2PS 12 Na 3.75 Sn 0.75 Sb 0.25 S4, Na 3.1 Sn 0.1 P 0.9 S4, Na4SiS4, Na 2.375 PS 3.375 Cl 0.625 Na3P 0.62 As 0.38 S4, Na3PSe4, Na 10 GeS2P 12 Na 10 SnS2P 12 Na 10 SiS2P 12 One or more of Na2S, K2S, and K3PS4.

[0015] Preferably, in the method for preparing the surface-modified sulfide solid electrolyte material, the dry gas containing carbon dioxide is specifically dry air or a dry mixture of carbon dioxide and an inert gas; the concentration of carbon dioxide in the dry gas containing carbon dioxide is 100%-0.001%.

[0016] Preferably, in the preparation method of the surface-modified sulfide solid electrolyte material, the time for introducing the dry gas containing carbon dioxide is between 0.1 hours and 24 hours;

[0017] The flow rate of the dry gas containing carbon dioxide is 50 cm. 3 / min-200cm 3 Between / min.

[0018] Preferably, in the method for preparing the surface-modified sulfide solid electrolyte material, the temperature of the reaction apparatus is between 20°C and 200°C.

[0019] Preferably, in the method for preparing the surface-modified sulfide solid electrolyte material, the reaction apparatus includes: a reaction vessel, valves, a flow meter, and a carbon dioxide gas source.

[0020] Thirdly, an all-solid-state battery comprising the surface-modified sulfide solid electrolyte material described in the first aspect above.

[0021] Fourthly, an all-solid-state battery according to the third aspect above, the all-solid-state battery comprising a positive electrode layer, a negative electrode layer and a solid electrolyte layer; the positive electrode layer comprising a surface-modified sulfide solid electrolyte material, and / or the negative electrode layer comprising a surface-modified sulfide solid electrolyte material, and / or the solid electrolyte layer comprising a surface-modified sulfide solid electrolyte material.

[0022] The surface-modified sulfide solid electrolyte material proposed in this invention greatly improves the chemical stability of sulfide solid electrolytes to air and alkali metal (lithium, sodium, potassium) negative electrodes and high-voltage oxide positive electrode materials, avoids the generation of a large number of inert byproducts during battery operation, and at the same time retains the high ionic conductivity of the sulfide solid electrolyte itself to the greatest extent, thus greatly improving the performance of all-solid-state batteries. Attached Figure Description

[0023] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0024] Figure 1 A schematic diagram of the reaction apparatus for preparing surface-modified sulfide solid electrolyte materials provided in an embodiment of the present invention;

[0025] Figure 2 The X-ray photoelectron spectroscopy (XPS) spectra of the surface-modified sulfide electrolyte materials provided in Examples 1-5 of this invention;

[0026] Figure 3 The first-cycle charge-discharge curve of an all-solid-state battery assembled with the surface-modified sulfide electrolyte material provided in Embodiment 1 of the present invention;

[0027] Figure 4 The first-cycle charge-discharge curve of an all-solid-state battery assembled with a surface-modified sulfide electrolyte material provided in Embodiment 2 of the present invention;

[0028] Figure 5 The first-cycle charge-discharge curve of an all-solid-state battery assembled with a surface-modified sulfide electrolyte material provided in Embodiment 3 of the present invention;

[0029] Figure 6 The first-cycle charge-discharge curve of an all-solid-state battery assembled with a surface-modified sulfide electrolyte material provided in Embodiment 4 of the present invention;

[0030] Figure 7 The first-cycle charge-discharge curve of an all-solid-state battery assembled with a surface-modified sulfide electrolyte material provided in Embodiment 5 of the present invention;

[0031] Figure 8 The first-week charge-discharge curve of an all-solid-state battery assembled with the surface-modified sulfide electrolyte material provided in Comparative Example 1 of this invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0033] This invention provides a surface-modified sulfide solid electrolyte material, comprising a sulfide solid electrolyte material and a protective film on the surface of the sulfide solid electrolyte material; wherein the protective film is obtained by modifying the sulfide solid electrolyte material with a drying gas containing carbon dioxide; the protective film comprises carbonates; and the thickness of the protective film is between 1 nm and 500 nm.

[0034] Among them, sulfide solid electrolyte materials include: Li 10 GeP2S 12 Li 6.6 P 0.4 Ge 0.6 S6I, Li7GePS8, Li7Ge3PS 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 SiP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li4SnS4, Li 10 SnP2S 12 Li₂SnS₃, Li₃PS₄, Li₇P₃S 11 , Li7PS6, Li2S·GeS2, Li2S·P2S5, Li2S·P2S5·LiI, Li2S·As2S5·SnS2, Li7P2S8I, Li4PS4I, Li7P 2.9 S 10.85 Mo 0.01, Li2CuPS4, (Li2S)9(P2S5)3(Ni3S2), Li7P 2.9 Mn 0.1 S 10.7 I 0.3 Li 10.35 Sn 0.27 Si 1.08 P 1.65 S 12 , Na3PS4, Na3SbS4, Na3SnS4, Na 11 Sn2PS 12 Na 3.75 Sn 0.75 Sb 0.25 S4, Na 3.1 Sn 0.1 P 0.9 S4, Na4SiS4, Na 2.375 PS 3.375 Cl 0.625 Na3P 0.62 As 0.38 S4, Na3PSe4, Na 10 GeS2P 12 Na 10 SnS2P 12 Na 10 SiS2P 12 One or more of Na2S, K2S, and K3PS4.

[0035] This invention provides a method for preparing the above-mentioned surface-modified sulfide solid electrolyte material, specifically including:

[0036] The sulfide solid electrolyte material is placed in a reaction apparatus, and a dry gas containing carbon dioxide is introduced. The carbon dioxide can combine with the alkali metal elements in the sulfide solid electrolyte to form a carbonate protective layer on the surface, while generating vacancies in the original sulfide solid electrolyte lattice, thus obtaining a surface-modified sulfide solid electrolyte material.

[0037] The temperature of the reaction apparatus is set between 0℃ and 500℃, and the preferred temperature of the reaction apparatus is between 20℃ and 200℃.

[0038] The concentration of carbon dioxide in the dry gas containing carbon dioxide is 100%-0.001%.

[0039] The flow rate of the dry gas containing carbon dioxide is 10 cm. 3 / mi n-5000cm 3 / mi n, preferably at 50cm 3 / min-200cm 3 / mi n between.

[0040] The time for introducing the dry gas containing carbon dioxide is 1 minute to 72 hours, preferably between 0.1 hours and 24 hours.

[0041] Reaction apparatus such as Figure 1 As shown, the apparatus includes: a reaction vessel 1, a valve 2, a flow meter 3, and a carbon dioxide gas source 4. The operating procedure of the reaction device is as follows: the sulfide solid electrolyte material is placed in the reaction device, and dry gas containing carbon dioxide is introduced into the reaction vessel 1 through the carbon dioxide gas source 4. The flow meter 3 is used to control the gas flow rate, and the valve 2 controls the gas inflow and outflow, so that the carbon dioxide can fully act on the surface of the sulfide solid electrolyte material.

[0042] This invention provides an all-solid-state battery, comprising the above-mentioned surface-modified sulfide solid electrolyte material.

[0043] This invention provides an application of a surface-modified sulfide solid electrolyte material, which can be used in at least one of the positive electrode layer, negative electrode layer, or electrolyte layer in an all-solid-state battery.

[0044] To better understand the technical solution provided by this invention, the following examples illustrate the surface-modified sulfide solid electrolyte material of this invention, its preparation method in batteries, its specific applications, and its characteristics.

[0045] Example 1

[0046] This embodiment provides a surface-modified sulfide solid electrolyte material and its all-solid-state battery, which is prepared by the following method, as detailed below:

[0047] In this embodiment, the sulfide solid electrolyte material used is Li6PS5Cl.

[0048] (1) Place Li6PS5Cl in a sealed reaction vessel and introduce 99.999% high-purity carbon dioxide gas, controlling the gas flow rate to be 100 cm⁻¹. 3 The reaction vessel was kept at a temperature of 25°C and the reaction time was 1 hour to obtain a surface-modified sulfide solid electrolyte material.

[0049] Chemical reaction equations for surface modification:

[0050] 2Li6PS5Cl+2CO2→Li2CO3+CO+2 Li5PS5Cl.

[0051] (2) The surface of the above-mentioned surface-modified sulfide solid electrolyte material was tested using X-ray photoelectron spectroscopy (XPS). Figure 2 As shown, through Figure 2Based on the displayed peaks and the XPS electron binding energy table, the peaks correspond to CO3. 2- This allows us to determine the presence of carbonates, and based on the reactants, we can ascertain that the surface of the sulfide solid electrolyte material contains lithium carbonate.

[0052] (3) The thickness of the lithium carbonate protective film was determined to be 65 nm by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0053] (4) In an argon glove box, the AC impedance was tested using a Bio-Logic electrochemical workstation to obtain the ionic conductivity of the above-mentioned surface-modified sulfide solid electrolyte. The data are detailed in Table 1.

[0054] (5) Air stability test: The surface-modified sulfide solid electrolyte material prepared above was placed in air with a relative humidity of 20% for 30 minutes. After that, the sample exposed to air was put back into an argon glove box and the ionic conductivity of the sample exposed to air was tested. The results are shown in Table 2.

[0055] (6) Fabrication of all-solid-state batteries:

[0056] The surface-modified sulfide solid electrolyte material and the positive electrode active material LiCoO2 prepared above were weighed at a mass ratio of 3:7 and ground and mixed in an agate mortar to make a composite positive electrode.

[0057] The sulfide solid electrolyte material Li6PS5Cl is pressed into an electrolyte sheet in a mold. The composite positive electrode and the lithium indium alloy negative electrode prepared above are placed on both sides of the electrolyte sheet, and then pressed into a sandwich structure to obtain an all-solid-state battery.

[0058] The all-solid-state battery prepared above was tested under the following conditions: charge / discharge voltage range of 2.0V-3.9V, constant current charge / discharge at a rate of 0.5C relative to the theoretical capacity of the battery, and a test temperature of 25℃. The charge / discharge curves for the first week are shown below. Figure 3 As shown, the specific reversible capacity is detailed in Table 1.

[0059] Example 2

[0060] This embodiment provides a surface-modified sulfide solid electrolyte material and its all-solid-state battery, which is prepared by the following method, as detailed below:

[0061] In this embodiment, the sulfide solid electrolyte material used is Li6PS5Cl.

[0062] (1) The preparation process and testing method of the surface-modified sulfide solid electrolyte material in this embodiment are the same as those in Example 1.

[0063] Li6PS5Cl was placed in a sealed reaction vessel, and 99.999% high-purity carbon dioxide gas was introduced, with the gas flow rate controlled at 100 cm⁻¹. 3 The reaction vessel was kept at a temperature of 25°C and the reaction time was 1 hour to obtain a surface-modified sulfide solid electrolyte material.

[0064] The chemical reaction equation for surface modification is the same as in Example 1.

[0065] (2) The surface of the above-mentioned surface-modified sulfide solid electrolyte material was tested using X-ray photoelectron spectroscopy (XPS). Figure 2 As shown, through Figure 2 Based on the displayed peaks and the XPS electron binding energy table, the peaks correspond to CO3. 2- This allows us to determine the presence of carbonates, and based on the reactants, we can ascertain that the surface of the sulfide solid electrolyte material contains lithium carbonate.

[0066] (3) The thickness of the lithium carbonate protective film was determined to be 65 nm by TOF-SIMS.

[0067] (4) In an argon glove box, the AC impedance was tested using a Bio-Logic electrochemical workstation to obtain the ionic conductivity of the above-mentioned surface-modified sulfide solid electrolyte. The data are detailed in Table 1.

[0068] (5) Air stability test: The surface-modified sulfide solid electrolyte material prepared above was placed in air with a relative humidity of 20% for 30 minutes. After that, the sample exposed to air was put back into an argon glove box and the ionic conductivity of the sample exposed to air was tested. The results are shown in Table 2.

[0069] (6) Fabrication of all-solid-state batteries:

[0070] The surface-modified sulfide solid electrolyte material and the positive electrode active material LiCoO2 prepared above were weighed at a mass ratio of 3:7 and ground and mixed in an agate mortar to make a composite positive electrode.

[0071] The surface-modified sulfide solid electrolyte material prepared above is pressed into an electrolyte sheet in a mold. The composite positive electrode and the lithium indium alloy negative electrode are placed on both sides of the electrolyte sheet respectively, and pressed into a sandwich structure to obtain an all-solid-state battery.

[0072] The all-solid-state battery prepared above was tested under the following conditions: charge / discharge voltage range of 2.0V-3.9V, constant current charge / discharge at a rate of 0.5C relative to the theoretical capacity of the battery, and a test temperature of 25℃. The charge / discharge curves for the first week are shown below. Figure 4 As shown, the specific reversible capacity is detailed in Table 1.

[0073] Example 3

[0074] This embodiment provides a surface-modified sulfide solid electrolyte material and its all-solid-state battery, which is prepared by the following method, as detailed below:

[0075] In this embodiment, the sulfide solid electrolyte material used is Li6PS5Cl.

[0076] (1) Place Li6PS5Cl in a sealed reaction vessel and introduce dry compressed air with a carbon dioxide content of 0.04%, controlling the gas flow rate to be 100 cm⁻¹. 3 The reaction was carried out at a rate of 1000 m / min, with the temperature of the sealed reaction vessel maintained at 25°C and the reaction time being 3 hours, to obtain a surface-modified sulfide solid electrolyte material.

[0077] Chemical reaction equations for surface modification:

[0078] 2Li6PS5Cl+2CO2→Li2CO3+CO+2 Li5PS5Cl.

[0079] (2) The surface of the above-mentioned surface-modified sulfide solid electrolyte material was tested, and the XPS values ​​were as follows: Figure 2 As shown, through Figure 2 Based on the displayed peaks and the XPS electron binding energy table, the peaks correspond to CO3. 2- This allows us to determine the presence of carbonates, and based on the reactants, we can ascertain that the surface of the sulfide solid electrolyte material contains lithium carbonate.

[0080] (3) The thickness of the lithium carbonate protective film was determined to be 20 nm by TOF-SIMS.

[0081] (4) In an argon glove box, the AC impedance was tested using a Bio-Logic electrochemical workstation to obtain the ionic conductivity of the above-mentioned surface-modified sulfide solid electrolyte. The data are detailed in Table 1.

[0082] (5) Air stability test: The surface-modified sulfide solid electrolyte material prepared above was placed in air with a relative humidity of 20% for 30 minutes. After that, the sample exposed to air was put back into an argon glove box and the ionic conductivity of the sample exposed to air was tested. The results are shown in Table 2.

[0083] (6) Fabrication of all-solid-state batteries:

[0084] The surface-modified sulfide solid electrolyte material and the positive electrode active material LiNi prepared above are combined. 0.8 Mn 0.1 Co 0.1 O2 was weighed at a mass ratio of 3:7 and ground and mixed in an agate mortar to make a composite positive electrode.

[0085] The surface-modified sulfide solid electrolyte material prepared above is pressed into an electrolyte sheet in a mold. The composite positive electrode and the lithium indium alloy negative electrode are placed on both sides of the electrolyte sheet respectively, and pressed into a sandwich structure to obtain an all-solid-state battery.

[0086] The all-solid-state battery prepared above was tested under the following conditions: charge / discharge voltage range of 2.0V-3.8V, constant current charge / discharge at a rate of 0.1C relative to the theoretical capacity of the battery, and a test temperature of 25℃. The charge / discharge curves for the first week are shown below. Figure 5 As shown, the specific reversible capacity is detailed in Table 1.

[0087] Example 4

[0088] This embodiment provides a surface-modified sulfide solid electrolyte material and its all-solid-state battery, which is prepared by the following method, as detailed below:

[0089] In this embodiment, the sulfide solid electrolyte material uses Li 10 GeP2S 12 .

[0090] (1) Li 10 GeP2S 12 Placed in a sealed reaction vessel, a mixture of nitrogen and carbon dioxide with a carbon dioxide content of 10% is introduced, and the gas flow rate is controlled at 50 cm⁻¹. 3 The reaction was carried out at a rate of 1 / min, maintaining the temperature of the sealed reaction vessel at 45°C for 1 hour, to obtain a surface-modified sulfide solid electrolyte material.

[0091] Chemical reaction equations for surface modification:

[0092] 2Li 10 GeP2S 12 +2CO2→Li2CO3+CO+2Li9GeP2S 12 .

[0093] (2) The surface of the above-mentioned surface-modified sulfide solid electrolyte material was tested using X-ray photoelectron spectroscopy (XPS). Figure 2 As shown, through Figure 2 Based on the displayed peaks and the XPS electron binding energy table, the peaks correspond to CO3. 2- This allows us to determine the presence of carbonates, and based on the reactants, we can ascertain that the surface of the sulfide solid electrolyte material contains lithium carbonate.

[0094] (3) The thickness of the lithium carbonate protective film was determined to be 44 nm by TOF-SIMS.

[0095] (4) In an argon glove box, the AC impedance was tested using a Bio-Logic electrochemical workstation to obtain the ionic conductivity of the above-mentioned surface-modified sulfide solid electrolyte. The data are detailed in Table 1.

[0096] (5) Air stability test: The surface-modified sulfide solid electrolyte material prepared above was placed in air with a relative humidity of 20% for 30 minutes. After that, the sample exposed to air was put back into an argon glove box and the ionic conductivity of the sample exposed to air was tested. The results are shown in Table 2.

[0097] (6) Fabrication of all-solid-state batteries:

[0098] The surface-modified sulfide solid electrolyte material and the positive electrode active material LiCoO2 prepared above were weighed at a mass ratio of 3:7 and ground and mixed in an agate mortar to make a composite positive electrode.

[0099] The surface-modified sulfide solid electrolyte material prepared above is pressed into an electrolyte sheet in a mold. The composite positive electrode and the lithium indium alloy negative electrode are placed on both sides of the electrolyte sheet respectively, and pressed into a sandwich structure to obtain an all-solid-state battery.

[0100] The all-solid-state battery prepared above was tested under the following conditions: charge / discharge voltage range of 2.0V-3.9V, constant current charge / discharge at a rate of 0.5C relative to the theoretical capacity of the battery, and a test temperature of 25℃. The charge / discharge curves for the first week are shown below. Figure 6 As shown, the specific reversible capacity is detailed in Table 1.

[0101] Example 5

[0102] This embodiment provides a surface-modified sulfide solid electrolyte material and its all-solid-state battery, which is prepared by the following method, as detailed below:

[0103] In this embodiment, the sulfide solid electrolyte material used is Na3PS4.

[0104] (1) Place Na3PS4 in a sealed reaction vessel and introduce 99.999% high-purity carbon dioxide gas, controlling the gas flow rate to be 100 cm⁻¹. 3 The reaction was carried out at a rate of 1 / min, maintaining the temperature of the sealed reaction vessel at 55°C for 1 hour, to obtain a surface-modified sulfide solid electrolyte material.

[0105] Chemical reaction equations for surface modification:

[0106] 2Na3PS4+2CO2→Na2CO3+CO+2Na2PS4.

[0107] (2) The surface of the above-mentioned surface-modified sulfide solid electrolyte material was tested using X-ray photoelectron spectroscopy (XPS). Figure 2 As shown, through Figure 2 Based on the displayed peaks and the XPS electron binding energy table, the peaks correspond to CO3. 2- This allows us to determine the presence of carbonates, and based on the reactants, we can ascertain that the surface of the sulfide solid electrolyte material contains sodium carbonate.

[0108] (3) The thickness of the sodium carbonate protective film was determined to be 82 nm by TOF-SIMS.

[0109] (4) In an argon glove box, the AC impedance was tested using a Bio-Logic electrochemical workstation to obtain the ionic conductivity of the above-mentioned surface-modified sulfide solid electrolyte. The data are detailed in Table 1.

[0110] (5) Air stability test: The surface-modified sulfide solid electrolyte material prepared above was placed in air with a relative humidity of 20% for 30 minutes. After that, the sample exposed to air was put back into an argon glove box and the ionic conductivity of the sample exposed to air was tested. The results are shown in Table 2.

[0111] (6) Fabrication of all-solid-state batteries:

[0112] The surface-modified sulfide solid electrolyte material prepared above and the positive electrode active material NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3O2 was weighed at a mass ratio of 3:7 and ground and mixed in an agate mortar to make a composite positive electrode.

[0113] The surface-modified sulfide solid electrolyte material prepared above is pressed into an electrolyte sheet in a mold, and the above-mentioned composite positive electrode and metallic sodium negative electrode are placed on both sides of the electrolyte sheet respectively, and pressed into a sandwich structure to obtain an all-solid-state battery.

[0114] The all-solid-state battery prepared above was tested under the following conditions: charge / discharge voltage range of 2.0V-4.1V, constant current charge / discharge at a rate of 0.1C relative to the theoretical capacity of the battery, and a test temperature of 25℃. The charge / discharge curves for the first week are shown below. Figure 7 As shown, the specific reversible capacity is detailed in Table 1.

[0115] To better illustrate the effects of the embodiments of the present invention, a performance comparison test and a material air stability comparison test were conducted on the all-solid-state battery made with the surface-modified sulfide solid electrolyte material of Example 2 and the all-solid-state battery made with the sulfide solid electrolyte material of Comparative Example 1.

[0116] Comparative Example 1

[0117] All-solid-state batteries were prepared according to the process parameters in Example 2. The difference is that the positive electrode material and electrolyte sheet of this comparative example did not use surface-modified sulfide solid electrolyte material. Instead, the electrolyte sheet was made of sulfide solid electrolyte material Li6PS5Cl, and LiCoO2 positive electrode and lithium indium alloy negative electrode were placed on both sides of the electrolyte sheet to obtain the all-solid-state battery of this comparative example.

[0118] The above-mentioned all-solid-state battery was tested, and its charge-discharge curve for the first week is as follows: Figure 8 As shown, the specific reversible capacity is detailed in Table 1.

[0119] Air stability comparison test: The sulfide solid electrolyte material Li6PS5Cl was placed in air with a relative humidity of 20% for 30 minutes. After that, the sample exposed to air was put back into an argon glove box to test the ionic conductivity after air exposure. The results are shown in Table 2.

[0120] Table 1 shows the ionic conductivity of the surface-modified sulfide electrolyte materials and the reversible capacity of the all-solid-state batteries in Examples 1-5 and Comparative Example 1. The comparison shows that the sulfide solid electrolyte material Li6PS5Cl in the all-solid-state battery suffers from reduced capacity and charge / discharge efficiency due to its strong chemical reaction with the positive electrode and the lithium-indium alloy negative electrode, while the surface-modified sulfide solid electrolyte improves performance.

[0121]

[0122] Table 1

[0123] Table 2 shows the ionic conductivity of the surface-modified sulfide electrolyte materials in Examples 1-5 and the original sulfide electrolyte material in Comparative Example 1 before and after exposure to air. The comparison shows that the original sulfide solid electrolyte material Li6PS5Cl has very poor air stability and is extremely sensitive to water; its ionic conductivity decreases significantly after exposure to air. In contrast, the surface-modified sulfide solid electrolyte material prepared in Example 2 has a carbonate protective layer on its surface, effectively isolating moisture from the air and improving its air stability. The ionic conductivity of the surface-modified sulfide electrolyte materials in Examples 3-4 also decreased after exposure to air, but the decrease was much smaller than that in Comparative Example 1.

[0124] serial number Ion conductivity before exposure to air Ion conductivity after exposure to air Examples 1 and 2 0.91 mS / cm 0.35mS / cm Example 3 2.02 mS / cm 0.88mS / cm Example 4 6.42 mS / cm 2.56 mS / cm Example 5 0.12mS / cm 0.078mS / cm Comparative Example 1 4.27 mS / cm 0.0021 mS / cm

[0125] Table 2

[0126] The surface-modified sulfide solid electrolyte material proposed in this invention greatly improves the chemical stability of sulfide solid electrolyte in air and on alkali metal (lithium, sodium, potassium) negative electrodes and high-voltage oxide positive electrodes, avoiding the generation of a large number of inert byproducts during battery operation. At the same time, it retains the high ionic conductivity of the sulfide solid electrolyte to the greatest extent, greatly improving the performance of all-solid-state batteries. The surface-modified sulfide solid electrolyte material provided by this invention is expected to be applied to next-generation high-energy-density batteries and has great practical value.

[0127] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A surface-modified sulfide solid electrolyte material, characterized in that, The surface-modified sulfide solid electrolyte material includes a sulfide solid electrolyte material and a protective film on the surface of the sulfide solid electrolyte material. The protective film is obtained by modifying the sulfide solid electrolyte material with a dry gas containing carbon dioxide; the components of the protective film include lithium carbonate or sodium carbonate. The surface-modified sulfide solid electrolyte material is obtained by placing the sulfide solid electrolyte material in a reaction apparatus, setting the temperature of the reaction apparatus between 0℃ and 55℃, and introducing a dry gas containing carbon dioxide. The carbon dioxide combines with the alkali metal elements in the sulfide solid electrolyte material to form a lithium carbonate or sodium carbonate protective layer on the surface, while simultaneously creating vacancies in the crystal lattice of the sulfide solid electrolyte material. The concentration of carbon dioxide in the dry gas is 99.999%, and the flow rate of the dry gas is 10 cm. 3 / min-5000cm 3 The rate of introduction of the dry gas containing carbon dioxide is between 1 minute and 72 hours; The sulfide solid electrolyte material includes: Li 10 GeP2S 12 Li 6.6 P 0.4 Ge 0.6 S6I, Li7GePS8, Li7Ge3PS 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 SiP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li4SnS4, Li 10 SnP2S 12 Li₂SnS₃, Li₃PS₄, Li₇P₃S 11 , Li7PS6, Li2S·GeS2, Li2S·P2S5, Li2S·P2S5·LiI, Li2S·As2S5·SnS2, Li7P2S8I, Li4PS4I, Li7P 2.9 S 10.85 Mo 0.01 , Li2CuPS4, (Li2S)9(P2S5)3(Ni3S2), Li7P 2.9 Mn 0.1 S 10.7 I 0.3 Li 10.35 Sn 0.27 Si 1.08 P 1.65 S 12 , Na3PS4, Na3SbS4, Na3SnS4, Na 11 Sn2PS 12 Na 3.75 Sn 0.75 Sb 0.25 S4, Na 3.1 Sn 0.1 P 0.9 S4, Na4SiS4, Na 2.375 PS 3.375 Cl 0.625 Na3P 0.62 As 0.38 S4, Na3PSe4, Na 10 GeS2P 12 Na 10 SnS2P 12 Na 10 SiS2P 12 One or more of Na2S; The thickness of the protective film is between 1 nm and 500 nm.

2. A method for preparing the surface-modified sulfide solid electrolyte material according to claim 1, characterized in that, The preparation method includes: A sulfide solid electrolyte material is placed in a reaction apparatus, the temperature of which is set between 0°C and 55°C, and a dry gas containing carbon dioxide is introduced to form a protective film on the surface of the sulfide solid electrolyte material. The protective film contains lithium carbonate or sodium carbonate. The surface-modified sulfide solid electrolyte material includes the sulfide solid electrolyte material and the protective film on its surface. The flow rate of the carbon dioxide-containing dry gas is 10 cm. 3 / min-5000cm 3 The rate is between 1 minute and 72 hours, during which the dry gas containing carbon dioxide is introduced. The sulfide solid electrolyte material includes: Li 10 GeP2S 12 Li 6.6 P 0.4 Ge 0.6 S6I, Li7GePS8, Li7Ge3PS 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 SiP2S 12 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li4SnS4, Li 10 SnP2S 12 Li₂SnS₃, Li₃PS₄, Li₇P₃S 11 , Li7PS6, Li2S·GeS2, Li2S·P2S5, Li2S·P2S5·LiI, Li2S·As2S5·SnS2, Li7P2S8I, Li4PS4I, Li7P 2.9 S 10.85 Mo 0.01 , Li2CuPS4, (Li2S)9(P2S5)3(Ni3S2), Li7P 2.9 Mn 0.1 S 10.7 I 0.3 Li 10.35 Sn 0.27 Si 1.08 P 1.65 S 12 , Na3PS4, Na3SbS4, Na3SnS4, Na 11 Sn2PS 12 Na 3.75 Sn 0.75 Sb 0.25 S4, Na 3.1 Sn 0.1 P 0.9 S4, Na4SiS4, Na 2.375 PS 3.375 Cl 0.625 Na3P 0.62 As 0.38 S4, Na3PSe4, Na 10 GeS2P 12 Na 10 SnS2P 12 Na 10 SiS2P 12 One or more of Na2S.

3. The method for preparing the surface-modified sulfide solid electrolyte material according to claim 2, characterized in that, The dry gas containing carbon dioxide is specifically a dry mixture of carbon dioxide and an inert gas; the concentration of carbon dioxide in the dry gas containing carbon dioxide is 99.999%.

4. The method for preparing the surface-modified sulfide solid electrolyte material according to claim 2, characterized in that, The time for introducing the dry gas containing carbon dioxide is between 0.1 hours and 24 hours; The flow rate of the dry gas containing carbon dioxide is 50 cm. 3 / min-200cm 3 Between / min.

5. The method for preparing the surface-modified sulfide solid electrolyte material according to claim 2, characterized in that, The temperature of the reaction device is between 20℃ and 55℃.

6. The method for preparing the surface-modified sulfide solid electrolyte material according to claim 2, characterized in that, The reaction apparatus includes: a reaction vessel, valves, a flow meter, and a carbon dioxide gas source.

7. An all-solid-state battery, characterized in that, The all-solid-state battery includes the surface-modified sulfide solid electrolyte material as described in claim 1.

8. The all-solid-state battery according to claim 7, characterized in that, The all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer; the positive electrode layer includes a surface-modified sulfide solid electrolyte material, and / or the negative electrode layer includes a surface-modified sulfide solid electrolyte material, and / or the solid electrolyte layer includes a surface-modified sulfide solid electrolyte material.

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