Solid electrolyte composite separator and method of making and use thereof

Abstract

This application relates to the field of lithium-ion battery technology, and in particular to a solid electrolyte composite separator, its preparation method, and its application, to reduce problems such as poor lithium plating that exist in sulfide solid electrolyte separators during use. A solid electrolyte composite separator is sheet-like; the solid electrolyte composite separator comprises: a first sulfide solid electrolyte matrix material, and a metal fluoride dispersed in the first sulfide solid electrolyte matrix material, wherein the metal fluoride is blended and bonded with the first sulfide solid electrolyte matrix material, and the metal fluoride fills the pores of the first sulfide solid electrolyte matrix material.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a solid electrolyte composite membrane, its preparation method, and its application. Background Technology

[0002] Traditional lithium-ion batteries typically use ethylene carbonate or similar materials as electrolytes. These thermodynamically unstable components make traditional liquid electrolyte lithium-ion batteries flammable and explosive in the event of thermal runaway, posing significant safety hazards. Furthermore, the liquid electrolytes in traditional lithium-ion batteries have low mechanical strength and a narrow electrochemical window, making them incompatible with high-energy lithium metal anodes for stable operation, thus hindering further improvements in battery energy density.

[0003] By replacing the liquid electrolyte with an inorganic solid electrolyte membrane that has high ionic conductivity, high stability, and high mechanical properties, and combining it with a metallic lithium anode, a solid-state lithium battery that balances high safety and high energy density can be obtained.

[0004] Currently, solid electrolytes, especially sulfide solid electrolytes, have achieved ionic conductivity levels comparable to or even exceeding those of liquid electrolytes. However, when a sulfide solid electrolyte membrane comes into contact with metallic lithium, several issues arise. First, the low density of the sulfide solid electrolyte membrane allows voids to form pathways for lithium dendrite growth during battery cycling. Second, the high electronic conductivity of the sulfide solid electrolyte membrane makes it prone to lithium plating, which can easily lead to internal short-circuit failure. Third, the thermodynamic instability at the interface between the sulfide solid electrolyte membrane and metallic lithium (e.g., the easy decomposition of lithium sulfide itself) also easily triggers lithium dendrite formation, accompanied by localized reactions and structural deterioration of the sulfide solid electrolyte, resulting in increased interfacial impedance. This cycle can repeatedly lead to open-circuit or short-circuit failure of the battery. Summary of the Invention

[0005] Therefore, it is necessary to provide a solid electrolyte composite membrane, its preparation method, and its application to reduce problems such as poor lithium plating that exist in sulfide solid electrolyte membranes during use.

[0006] In a first aspect, this application provides a solid electrolyte composite membrane, the solid electrolyte composite membrane being sheet-like; the solid electrolyte composite membrane comprising: a first sulfide solid electrolyte matrix material, and a metal fluoride dispersed in the first sulfide solid electrolyte matrix material, wherein the metal fluoride is blended and bonded with the first sulfide solid electrolyte matrix material, and the metal fluoride fills the pores of the first sulfide solid electrolyte matrix material.

[0007] Optionally, the metal fluoride includes one or more of aluminum fluoride, zirconium fluoride, and lithium fluoride.

[0008] Optionally, the first sulfide solid electrolyte matrix material includes at least: Li, Group 6 elements, and Group 5 elements.

[0009] Optionally, the mass ratio of the metal fluoride to the first sulfide solid electrolyte matrix material is 1:500 to 1:15.

[0010] Optionally, the solid electrolyte composite membrane comprises: (100-xy)Li₂S·xP₂S₅·yM m N n ·zLi a Al b Zr c F d Li 10±v Ge l-g G g P 2-q QS 12-w W w ·zLi a Al b Zr c F d and Li 6±u P 1-e E e S 5±u-r R r X 1±u ·zLi a Al b Zr c F d One or more of the following;

[0011] Among them, in (100-xy)Li2S·xP2S5·yM m N n ·zLi a Al b Zr c F d In the given information, 0 ≤ x < 100, 0 ≤ y < 100, 0 ≤ x + y < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more of Li, Ge, Si, Sn and Sb, N is selected from one or more of Se, O, Cl, Br and I, 0.01 ≤ z < 50, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, d = a + 3b + 4c;

[0012] In Li 10±v Ge 1-g G g P 2-q QS 12-w Ww ·zLi a Al b Zr c F d In the given information, 0 ≤ v < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is Si and / or Sn, Q is Sb, W is one or more of O, Se, Cl, Br, and I, 0.002 ≤ z < 2, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, and d = a + 3b + 4c.

[0013] In Li 6±u P 1-e E e S 5±u-r R r X 1±u ·zLi a Al b Zr c F d In the given information, 0 ≤ u < 1, 0 ≤ e < 1, 0 ≤ r < 1, E is one or more of Ge, Si, Sn, and Sb, R is O and / or Se, X is one or more of Cl, Br, and I, 0.001 ≤ z < 1, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, and d = a + 3b + 4c.

[0014] Optionally, the room temperature ionic conductivity of the solid electrolyte composite membrane is 1×10⁻⁶. -6 S / cm ~ 1×10 -1 S / cm, room temperature electronic conductivity 1×10 -12 S / cm ~1×10 -7 S / cm.

[0015] In a second aspect, a method for preparing a solid electrolyte composite membrane as described in the first aspect is provided, comprising:

[0016] A pre-fabricated sheet-like diaphragm is prepared by mixing powder of a second sulfide electrolyte matrix material and powder of a fluorine-containing compound and pressing them into tablets.

[0017] The prefabricated sheet membrane is sintered to allow the second sulfide electrolyte matrix material and the fluorine-containing compound in the prefabricated sheet membrane to undergo an in-situ solid-phase reaction, generating the metal fluoride and the first sulfide electrolyte matrix material. The metal fluoride and the first sulfide electrolyte matrix material are blended and bonded together, and the metal fluoride fills the pores of the first sulfide electrolyte matrix material.

[0018] Optionally, the fluorinated compound includes one or more of NH4F3, NH4AlF4, and (NH4)3ZrF7.

[0019] Optionally, the second sulfide electrolyte matrix material comprises: (100-xy)Li₂S·xP₂S₅·yM m N n Li 10±v Ge l-g G g P 2-q QS 12-w W w and Li 6±u P 1-e E e S 5±u-r R r X 1±u One or more of the following;

[0020] Among them, in (100-xy)Li2S·xP2S5·yM m N n In this context, 0 ≤ x < 100, 0 ≤ y < 100, 0 ≤ x + y < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more of Li, Ge, Si, Sn and Sb, and N is selected from one or more of Se, O, Cl, Br and I;

[0021] In Li 10±v Ge 1-g G g P 2-q QS 12-w W w In this context, 0 ≤ v < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is Si and / or Sn, Q is Sb, and W is one or more of O, Se, Cl, Br, and I.

[0022] In Li 6±u P 1-e E e S 5±u-r R r X 1±u In this context, 0 ≤ u < 1, 0 ≤ e < 1, 0 ≤ r < 1, E is one or more of Ge, Si, Sn, and Sb, R is O and / or Se, and X is one or more of Cl, Br, and I.

[0023] Optionally, the mass ratio of the fluorine-containing compound powder to the powder of the second sulfide electrolyte matrix material is 1:200 to 1:10.

[0024] Optionally, the tablet compression pressure is 1 MPa to 720 MPa, and the compression time is 0.1 min to 30 min.

[0025] Optionally, the sintering temperature is 30℃~500℃ and the time is 0.5h~48h.

[0026] Thirdly, a solid-state battery is provided, comprising: a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is a solid electrolyte composite separator as described in the first aspect.

[0027] Fourthly, a battery module is provided, comprising: a plurality of lithium-ion batteries electrically connected, wherein at least one lithium-ion battery is a solid-state battery as described in the third aspect.

[0028] Fifthly, an electrical device is provided, comprising: a solid-state battery as described in the third aspect or a battery module as described in the fourth aspect.

[0029] Compared with related technologies, the beneficial technical effects of this application are as follows:

[0030] Because metal fluorides have lower electronic conductivity than sulfide solid electrolytes, the introduction of metal fluorides can, firstly, reduce electron transfer during use of the solid electrolyte composite membrane, thereby reducing redox reactions at the interface between the solid electrolyte composite membrane and lithium metal, and secondly, reducing lithium ion (Li) ion concentration. + Lithium dendrites form at the interface and inside the solid electrolyte composite membrane by gaining electrons. On the other hand, lithium salts such as lithium sulfide and lithium fluoride in the solid electrolyte composite membrane are not easily affected by lithium ions (Li... + Firstly, the structure deteriorates due to reduction, which can improve the thermodynamic stability of the solid electrolyte composite membrane. Secondly, the metal fluoride is relatively dense, and after being introduced into the sulfide solid electrolyte, the metal fluoride can also prevent lithium dendrites from piercing the solid electrolyte composite membrane, thereby further improving the stability of the solid electrolyte composite membrane during use. Thirdly, before the introduction of the metal fluoride, pores that can be formed in the sulfide solid electrolyte for lithium dendrite growth are formed. With the introduction of the metal fluoride, the metal fluoride can fill the pores, thereby reducing the growth path of lithium dendrites. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application 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 this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "exemplary," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0033] In this document, unless otherwise stated, "one or more" means one or more.

[0034] In this document, terms such as "for example," "like," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later. However, they should not be construed as limitations on the preceding technical solution or as restrictions on the scope of protection outlined herein. Unless otherwise specified, in this document, A (e.g., B) indicates that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0035] In this article, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "options" in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "option" is independent.

[0036] In this document, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features.

[0037] 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0038] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0039] In this document, when referring to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints (i.e., the minimum and maximum values) of the numerical interval, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, and other numerical interval types.

[0040] In this document, temperature parameters are used. Unless otherwise specified, both isothermal processing and processing within a certain temperature range are permitted. The isothermal processing allows temperature fluctuations within the precision range controlled by the instrument.

[0041] Based on the above technical problems, in a first aspect, some embodiments of this application provide a solid electrolyte composite membrane, which is sheet-like; the solid electrolyte composite membrane includes: a first sulfide solid electrolyte matrix material, and a metal fluoride dispersed in the first sulfide solid electrolyte matrix material, wherein the metal fluoride is blended and bonded with the first sulfide solid electrolyte matrix material, and the metal fluoride fills the pores of the first sulfide solid electrolyte matrix material.

[0042] Metal fluorides are binary compounds composed of fluoride ions and metal ions. The type of metal ion and its introduction can be categorized into two possibilities:

[0043] In the first case, the metal ion can be a metal ion contained in the sulfide solid electrolyte itself, such as Li. + At this point, some of the S in the sulfide solid electrolyte... 2- It can be F - Replacement can be achieved by introducing fluorinated compounds (such as hydrogen fluoride or ammonium fluoride) and heating them to react with the sulfide solid electrolyte, thereby removing some of the sulfur. 2- The lithium fluoride and first sulfide solid electrolyte matrix material can be obtained by converting the hydrogen sulfide gas into hydrogen sulfide gas and releasing it.

[0044] In the second scenario, the metal ion can be a newly introduced metal ion into the solid electrolyte composite membrane. In this case, the metal ion will not affect the use of the solid electrolyte composite membrane. For the specific introduction method, please refer to the description of the first scenario. The only difference is that the fluorine-containing compound can be ammonium fluoride.

[0045] Based on the above two situations, since metal fluorides have lower electronic conductivity than sulfide solid electrolytes, the introduction of metal fluorides can, firstly, reduce electron transfer during use of the solid electrolyte composite membrane, thereby reducing the redox reaction between the solid electrolyte composite membrane and the lithium metal interface, and secondly, reduce lithium ion (Li... + Lithium dendrites form at the interface and inside the solid electrolyte composite membrane by gaining electrons. On the other hand, lithium salts such as lithium sulfide and lithium fluoride in the solid electrolyte composite membrane are not easily affected by lithium ions (Li... + Firstly, the structure deteriorates due to reduction, which can improve the thermodynamic stability of the solid electrolyte composite membrane. Secondly, the metal fluoride is relatively dense, and after being introduced into the sulfide solid electrolyte, the metal fluoride can also prevent lithium dendrites from piercing the solid electrolyte composite membrane, thereby further improving the stability of the solid electrolyte composite membrane during use. Thirdly, before the introduction of the metal fluoride, pores that can be formed in the sulfide solid electrolyte for lithium dendrite growth are formed. With the introduction of the metal fluoride, the metal fluoride can fill the pores, thereby reducing the growth path of lithium dendrites.

[0046] In summary, the solid electrolyte composite membrane provided in this application embodiment can reduce the occurrence of problems such as poor lithium plating during use.

[0047] The metal fluoride filling the pores of the first sulfide solid electrolyte matrix material can be obtained using a scanning electron microscope.

[0048] In some embodiments, the metal fluoride includes one or more of aluminum fluoride, zirconium fluoride, and lithium fluoride.

[0049] The introduction of lithium fluoride can be described in the manner of the first case of metal ion introduction mentioned above; zirconium fluoride and aluminum fluoride are relatively common metal fluorides that will not affect the use of the solid electrolyte composite membrane; and aluminum fluoride, zirconium fluoride and lithium fluoride all have ultra-low electronic conductivity, which can minimize lithium dendrite precipitation.

[0050] In some embodiments, the first sulfide solid electrolyte matrix material includes at least: Li, Group 6 elements, and Group 5 elements.

[0051] The sixth main group element may include one or more of S, Se and O, and the fifth main group element may include one or more of P and Sb.

[0052] In these embodiments, Li can exist in cationic form, such as lithium ions (Li₂). + Group 6 elements can exist in anionic form, such as S. 2- O 2- Group 5 elements can exist in cation form, such as P. 5+ and Sb 5+ The first sulfide solid electrolyte matrix material has good ionic conductivity, which facilitates the conduction of electricity by the directional movement of ions in the solid electrolyte composite membrane.

[0053] In some embodiments, the first sulfide solid electrolyte matrix material may further include: a Group 4 element and one or more of Cl, Br and I elements.

[0054] The fourth group element may, for example, include one or more of Ge, Si, and Sn, and may exist in the form of a cation, such as Ge. 4+ Si 4+ and Sn 4+ Element Cl, Br, and I can exist in anionic form, for example, Cl... - ,Br - and I - wait.

[0055] In some embodiments, the mass ratio of the metal fluoride to the first sulfide solid electrolyte matrix material is 1:500 to 1:15.

[0056] The elemental composition of the metal fluoride and the first sulfide solid electrolyte matrix material can be obtained by X-ray photoelectron spectroscopy and X-ray diffraction analysis.

[0057] In some embodiments, the solid electrolyte composite membrane comprises: (100-xy)Li2S·xP2S5·yM m N n ·zLi a Al b Zr c F d Li 10±v Ge l-g G g P 2-q QS 12-w W w ·zLi a Al b Zr cF d and Li 6±u P 1-e E e S 5±u-r R r X 1±u ·zLi a Al b Zr c F d One or more of the following;

[0058] Among them, in (100-xy)Li2S·xP2S5·yM m N n ·zLi a Al b Zr c F d In the given information, 0 ≤ x < 100, 0 ≤ y < 100, 0 ≤ x + y < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more of Li, Ge, Si, Sn and Sb, N is selected from one or more of Se, O, Cl, Br and I, 0.01 ≤ z < 50, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, d = a + 3b + 4c;

[0059] In Li 10±v Ge 1-g G g P 2-q QS 12-w W w ·zLi a Al b Zr c F d In the given information, 0 ≤ v < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is Si and / or Sn, Q is Sb, W is one or more of O, Se, Cl, Br, and I, 0.002 ≤ z < 2, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, and d = a + 3b + 4c.

[0060] In Li 6±u P 1-e E e S 5±u-r R r X 1±u ·zLi a Al b Zr c F d In the given information, 0 ≤ u < 1, 0 ≤ e < 1, 0 ≤ r < 1, E is one or more of Ge, Si, Sn, and Sb, R is O and / or Se, X is one or more of Cl, Br, and I, 0.001 ≤ z < 1, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, and d = a + 3b + 4c.

[0061] It should be noted that after the fluorine-containing compound reacts with the sulfide solid electrolyte (as described in the second sulfide solid electrolyte below) to introduce metal fluoride into the sulfide solid electrolyte, only a very small amount of S remains in the sulfide solid electrolyte. 2- The hydrogen sulfide generated in the reaction is released. Therefore, the elemental composition of the first sulfide solid electrolyte in the solid electrolyte composite membrane changes very little compared to the sulfide solid electrolyte before the reaction. Thus, the first sulfide solid electrolyte in the solid electrolyte composite membrane is represented by the same molecular formula as the sulfide solid electrolyte before the reaction. Those skilled in the art will understand that the subscript of the sulfur element in the first sulfide solid electrolyte changes compared to the sulfide solid electrolyte before the reaction, but because the change is very small, this change is not reflected here.

[0062] In some embodiments, the compaction density of the solid electrolyte composite membrane is 85% to 95%.

[0063] In these embodiments, the compaction density of the solid electrolyte composite membrane is improved to some extent compared to that of the sulfide solid electrolyte.

[0064] In some embodiments, the room temperature ionic conductivity of the solid electrolyte composite membrane is 1×10⁻⁶. -6 S / cm ~ 1×10 -1 S / cm, room temperature electronic conductivity 1×10 -12 S / cm ~ 1×10 -7 S / cm.

[0065] Conductors conduct electricity by relying on the directional movement (also known as directional migration) of ions within the conductor. These conductors are called ionic conductors and include aqueous electrolyte solutions, organic electrolyte solutions, molten salts, and solid electrolytes.

[0066] The room temperature can be 10℃~40℃, or optionally 20℃~30℃.

[0067] In these embodiments, the room-temperature ionic conductivity of the solid electrolyte composite membrane can be obtained by electrochemical impedance spectroscopy at room temperature, and the room-temperature electronic conductivity can be obtained by direct current method (e.g., using an ion-blocking electrode) at room temperature. Therefore, the solid electrolyte composite membrane exhibits high ionic conductivity and ultra-low electronic conductivity, allowing for charge conduction using its high ionic conductivity and reducing lithium plating using its low electronic conductivity.

[0068] Secondly, some embodiments of this application provide a method for preparing a solid electrolyte composite membrane as described in the first aspect, the method comprising:

[0069] A pre-fabricated sheet-like diaphragm is prepared by mixing powder of a second sulfide electrolyte matrix material and powder of a fluorine-containing compound and pressing them into tablets.

[0070] The prefabricated sheet-like membrane is sintered, causing the second sulfide electrolyte matrix material and the fluorine-containing compound in the prefabricated sheet-like membrane to undergo an in-situ solid-phase reaction, generating metal fluoride and first sulfide electrolyte matrix material. The metal fluoride and first sulfide electrolyte matrix material are blended and bonded together, and the metal fluoride fills the pores of the first sulfide electrolyte matrix material.

[0071] In-situ solid-phase reaction refers to a chemical reaction that occurs within a solid material, specifically within a pre-fabricated sheet-like membrane. For example, taking ammonium fluoride as the fluorinated compound, during sintering, ammonium fluoride reacts with the second sulfide electrolyte matrix material to generate hydrogen sulfide, ammonia, and lithium fluoride. Lithium fluoride can precipitate from the second sulfide electrolyte matrix material, while hydrogen sulfide and ammonia can be volatilized and removed. The second sulfide electrolyte matrix material is then transformed into the first sulfide electrolyte matrix material, allowing lithium fluoride to fill the pores within it.

[0072] In some embodiments, the fluorinated compound includes one or more of NH4F3, NH4AlF4, and (NH4)3ZrF7.

[0073] In these embodiments, when the fluorinated compound is NH4F3, the specific reaction process can be found in the description above. When the fluorinated compound is NH4AlF4 or (NH4)3ZrF7, the specific reaction process can also be found in the description above, the difference being that in addition to generating lithium fluoride, aluminum fluoride or zirconium fluoride is also generated. These metal fluorides have extremely low electronic conductivity, which can minimize the electronic conductivity of the solid electrolyte composite membrane. In addition, these fluorinated compounds have a certain degree of alkalinity and will not introduce hydrogen ions into the solid electrolyte composite membrane, thereby improving the stability of the solid electrolyte composite membrane.

[0074] In some embodiments, the second sulfide electrolyte matrix material comprises: (100-xy)Li₂S·xP₂S₅·yM m N n Li 10±v Ge 1-g G g P 2-q QS 12-w W w and Li 6±u P1-e E e S 5±u-r R r X 1±u One or more of the following;

[0075] Among them, in (100-xy)Li2S·xP2S5·yM m N n In this context, 0 ≤ x < 100, 0 ≤ y < 100, 0 ≤ x + y < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more of Li, Ge, Si, Sn and Sb, and N is selected from one or more of Se, O, Cl, Br and I;

[0076] In Li 10±v Ge 1-g G g P 2-q QS 12-w W w In this context, 0 ≤ v < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is Si and / or Sn, Q is Sb, and W is one or more of O, Se, Cl, Br, and I.

[0077] In Li 6±u P 1-e E e S 5±u-r R r X 1±u In this context, 0 ≤ u < 1, 0 ≤ e < 1, 0 ≤ r < 1, E is one or more of Ge, Si, Sn, and Sb, R is O and / or Se, and X is one or more of Cl, Br, and I.

[0078] In these embodiments, the second sulfide solid electrolyte matrix material itself has a relatively high ionic conductivity, which can maintain the high ionic conductivity of the solid electrolyte composite membrane as much as possible, and can achieve good lithium-ion conduction.

[0079] In some embodiments, the mass ratio of the powder containing the fluorine compound to the powder of the second sulfide electrolyte matrix material is 1:200 to 1:10.

[0080] In these embodiments, by controlling the mass ratio of the fluorine-containing compound to the second sulfide solid electrolyte matrix material within the range of 1:200 to 1:10, the stability of the solid electrolyte composite membrane can be improved, lithium dendrite precipitation can be reduced, and the capacity of the battery in which it is applied can be unaffected.

[0081] In some embodiments, the particle size of the fluorine-containing compound powder and the second sulfide solid electrolyte matrix material is 10 nm to 100 μm.

[0082] In some embodiments, the pressure during tablet compression is 1 MPa to 720 MPa, and the time is 0.1 min to 30 min.

[0083] In these embodiments, tableting can be performed at room temperature using a tablet press, which can be a manual tablet press, a hydraulic tablet press, or a mechanical tablet press. Specifically, the powder containing fluorine compounds and the powder of the second sulfide solid electrolyte matrix material are mixed evenly in a certain proportion, and the mixed powder is filled into the die cavity of the press. The mixed powder is then pressed into a tablet shape using a punch. During this process, by controlling the pressure during tableting to 1 MPa to 720 MPa and the time to 0.1 min to 30 min, the compaction density of the solid electrolyte composite membrane can be controlled to 85% to 95%. Compared with the compaction density of sulfide solid electrolytes, which is around 85%, this effectively reduces the porosity in the solid electrolyte composite membrane. That is, the fluorine compounds can fill the pores in the first sulfide solid electrolyte matrix material, thereby reducing the lithium dendrite growth path.

[0084] In some alternative embodiments, the pressure during tablet compression is 60 MPa to 500 MPa, and the time is 1 min to 10 min.

[0085] In some embodiments, the sintering temperature is 30°C to 500°C and the time is 0.5h to 48h.

[0086] In these embodiments, by controlling the sintering temperature to be 30°C to 500°C and the time to be 0.5h to 48h, the ammonia and hydrogen sulfide gases generated by the reaction of the fluorine compound powder and the second sulfide electrolyte matrix material powder can be removed as completely as possible, thereby further improving the thermodynamic stability of the solid electrolyte composite membrane.

[0087] Secondly, some embodiments of this application provide a solid-state battery, which includes: a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is a solid electrolyte composite separator as described in the first aspect.

[0088] The solid-state battery can be a lithium-ion battery, and the positive electrode of the lithium-ion battery can include positive electrode active material, conductive agent and electrolyte, etc., while the negative electrode can include metallic lithium.

[0089] Thirdly, a battery module is provided, comprising: a plurality of lithium-ion batteries electrically connected, wherein at least one lithium-ion battery is a solid-state battery as described in the second aspect.

[0090] Fourthly, an electrical device is provided, comprising: a solid-state battery as described in the second aspect or a battery module as described in the third aspect.

[0091] The electrical device described in this application can be any device that uses the electrochemical device according to the embodiments of this application.

[0092] In some embodiments, the electrical device includes, but is not limited to: laptop computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries or lithium-ion capacitors, etc.

[0093] In order to objectively evaluate the technical effects of the embodiments of this application, this application will be described in detail by way of example through the following embodiments and comparative examples.

[0094] In the following examples and comparative examples, all raw materials were commercially available, and to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples had the same physical and chemical parameters or were prepared by the same processing method.

[0095] Furthermore, in the following examples and comparative examples, unless otherwise specified, slight deviations may exist within the weighing accuracy range for the measurement parameters of the raw material components. For temperature and time parameters, acceptable deviations due to instrument testing accuracy or operational precision are permissible.

[0096] Comparative Example 1

[0097] Comparative Example 1 provides an all-solid-state lithium battery, the preparation method of which is as follows:

[0098] Step 1) Preparation of sulfide solid electrolyte membrane:

[0099] Under an argon atmosphere, Li₂S, P₂S₅, and GeS₂ with a purity of ≥99% were weighed according to stoichiometry and ground at 200 rpm to obtain a homogeneous mixture with a water content of less than 10 ppm. The mixture was then planetarily ball-milled for 24 h at a ball-to-material ratio of 1:10 to obtain a raw powder. The raw powder was then pressed into sheets under a pressure of 240 MPa and heated to 600 °C at a heating rate of 2.5 °C / min, held at that temperature for 16 h, cooled to room temperature, and then sintered into sheet form with a water content of less than 10 ppm to obtain Li₂S. 10 GeP2S 12 A sulfide solid electrolyte membrane was used, and its room temperature ionic conductivity was measured to be 6.4 × 10⁻⁶. -3S / cm, room temperature electronic conductivity 4.9×10 -8 S / cm.

[0100] Step 2) Preparation of all-solid-state lithium batteries:

[0101] The sulfide solid electrolyte membrane, LiCoO2 positive electrode and lithium metal negative electrode prepared in step 1) are assembled into an all-solid-state lithium battery.

[0102] Example 1

[0103] Example 1 provides an all-solid-state lithium battery, the preparation method of which is as follows:

[0104] Step 1) Preparation of sulfide solid electrolyte membrane:

[0105] Under an argon atmosphere, Li₂S, P₂S₅, and GeS₂ with a purity of ≥99% were weighed according to stoichiometry. The mixture was then ground and mixed uniformly at 200 rpm with a water content of less than 10 ppm. Afterward, the mixture was planetarily ball-milled for 24 hours at a ball-to-material ratio of 1:10 to obtain a raw powder. The raw powder was then finely ground and heated to 600℃ at a heating rate of 2.5℃ / min, held at that temperature for 16 hours, and cooled to room temperature. The sintered product was then obtained under conditions where the water content was less than 10 ppm, yielding Li₂S, P₂S₅, and GeS₂ with a purity of ≥99% by stoichiometry. 10 GeP2S 12 Sulfide solid electrolyte powder.

[0106] Li with a mass ratio of 200:1 10 GeP2S 12 Sulfide solid electrolyte powder and (NH4)3ZrF7 powder were mixed evenly, pressed into sheets under a pressure of 240 MPa, and then heated to 500 °C at a rate of 1 °C / min and held for 1 h to obtain LiF containing ZrF4 and LiF. 10 GeP2S 12 Sulfide solid electrolyte membrane Li 10 GeP2S 12 ·2.3×10 -2 Li 2.7 ZrF 6.7 The room temperature ionic conductivity of the sulfide solid electrolyte membrane was measured to be 6.1 × 10⁻⁶. -3 S / cm, room temperature electronic conductivity is 2.3×10 -10 S / cm.

[0107] Step 2) Preparation of all-solid-state lithium batteries:

[0108] The sulfide solid electrolyte membrane, LiCoO2 positive electrode and lithium metal negative electrode prepared in step 1) are assembled into an all-solid-state lithium battery.

[0109] Example 2

[0110] Example 2 provides an all-solid-state lithium battery, the preparation method of which is as follows:

[0111] Step 1) Preparation of sulfide solid electrolyte membrane:

[0112] Under an argon atmosphere, Li2S, P2S5, and LiCl with a purity of ≥99% were weighed according to stoichiometry. They were then ground and mixed uniformly at 200 rpm with a water content of less than 10 ppm. After that, they were ball-milled in a planetary ball mill for 4 hours at a mass ratio of 1:1 to obtain a powder. The powder was then taken out, ground into a fine powder, and heated to 550℃ at a heating rate of 5℃ / min. The temperature was held for 16 hours to obtain Li6PS5Cl sulfide solid electrolyte powder.

[0113] Li6PS5Cl sulfide solid electrolyte powder, NH4AlF4 powder, and (NH4)3ZrF7 powder were mixed uniformly in a mass ratio of 100:10:1. The mixture was then pressed into sheets under a pressure of 60 MPa and heated to 370 °C at a rate of 2 °C / min, and held for 24 h to obtain a Li6PS5Cl sulfide solid electrolyte membrane containing ZrF4, AlF3, and LiF. (Li6PS5Cl·7.1×10⁻⁶) -3 Li 1.2 AlZr 0.1 F 4.6 The room temperature ionic conductivity of the sulfide solid electrolyte membrane was measured to be 3.1 × 10⁻⁶. -3 S / cm, room temperature electronic conductivity is 7.1×10 -11 S / cm.

[0114] Step 2) Preparation of all-solid-state lithium batteries:

[0115] The sulfide solid electrolyte membrane prepared in step 1), LiNi 0.8 Co 0.1 Mn 0.102 The positive electrode and the lithium metal negative electrode are assembled into an all-solid-state lithium battery.

[0116] Example 3

[0117] Example 3 provides an all-solid-state lithium battery, the preparation method of which is as follows:

[0118] Step 1) Preparation of sulfide solid electrolyte membrane:

[0119] Under an argon atmosphere, Li2S and P2S5 with a purity of ≥99% were weighed according to stoichiometry. They were ground and mixed evenly at 150 rpm under conditions where the water content was less than 10 ppm. The powder was then removed, sealed in a vacuum quartz tube, and heated to 280°C at a heating rate of 1.5°C / min. The temperature was maintained for 24 h, and then cooled to room temperature. The product was removed and ground evenly under conditions where the water content was less than 10 ppm to obtain Li3PS4 sulfide solid electrolyte.

[0120] Li3PS4 sulfide solid electrolyte powder and NH4AlF4 powder were mixed evenly at a mass ratio of 20:1. The mixture was then pressed into sheets under a pressure of 360 MPa and heated to 170 °C at a rate of 1 °C / min, and held at this temperature for 48 h to obtain a Li3PS4 sulfide solid electrolyte membrane (Li3PS4·0.37LiAlF4) containing AlF3 and LiF. The room temperature ionic conductivity of this sulfide solid electrolyte membrane was measured to be 1.8 × 10⁻⁶. -3 S / cm, room temperature electronic conductivity is 1.4×10 -9 S / cm.

[0121] Step 2) Preparation of all-solid-state lithium batteries:

[0122] The sulfide solid electrolyte membrane, LiCoO2 positive electrode and lithium metal negative electrode prepared in step 1) are assembled into an all-solid-state lithium battery.

[0123] Test case

[0124] 1. Electrochemical performance tests were performed on the all-solid-state lithium batteries provided in Examples 1-3 and Comparative Example 1.

[0125] During the test, the battery provided in Comparative Example 1 was charged and discharged in a voltage range of 2.0 V to 4.2 V and a rate of 0.1 C. The constant rate charge and discharge test results showed that the battery provided in Comparative Example 1 retained approximately 0.8% of its capacity after 100 charge and discharge cycles.

[0126] During the test, the battery provided in Example 1 was charged and discharged in a voltage range of 2.0 V to 4.2 V and a rate of 0.1 C. The constant rate charge and discharge was performed. The test results showed that after 100 charge and discharge cycles, the battery provided in Example 1 retained approximately 94.6% of its capacity.

[0127] During the test, the battery provided in Example 2 was charged and discharged in a voltage range of 2.0 V to 4.25 V and a rate of 1C. The constant rate charge and discharge was performed. The test results showed that the battery provided in Example 1 retained approximately 86.1% of its capacity after 500 charge and discharge cycles.

[0128] During the test, the battery provided in Example 3 was charged and discharged in a voltage range of 2.0 V to 4.2 V and a rate of 0.2 C. The constant rate charge and discharge was performed. The test results showed that after 200 charge and discharge cycles, the battery provided in Example 3 retained approximately 91.4% of its capacity.

[0129] 2. Lithium sheets were attached to both sides of the sulfide solid electrolyte membranes provided in Examples 1-3 and Comparative Example 1 for lithium / / lithium symmetric battery cycle testing.

[0130] In Comparative Example 1, the current density during the test was 0.1 mA / cm². 2 The test results showed that the lithium / / lithium symmetric battery made with the sulfide solid electrolyte membrane provided in Comparative Example 1 only cycled for 300 hours at room temperature.

[0131] In Example 1, the current density during the test was 0.1 mA / cm². 2 The test results showed that the lithium / / lithium symmetric battery made with the sulfide solid electrolyte membrane provided in Example 1 could cycle stably for 1500 hours at room temperature.

[0132] In Example 2, the current density during the test was 0.5 mA / cm². 2 The test results show that the lithium / / lithium symmetric battery made with the sulfide solid electrolyte membrane provided in Example 2 can be stably cycled for 2000 hours at room temperature.

[0133] In Example 3, the current density during the test was 0.1 mA / cm². 2 The test results showed that the lithium / / lithium symmetric battery made with the sulfide solid electrolyte membrane provided in Example 3 could be stably cycled for 2100 hours at room temperature.

[0134] In summary, by mixing and pressing sulfide solid electrolyte powder with fluorine-containing compound powders such as NH4AlF4 powder and (NH4)3ZrF7 powder and then carrying out in-situ solid-phase reaction, metal fluorides such as AlF3, LiF and ZrF4 can be precipitated in the sulfide solid electrolyte. Tests have shown that after introducing these metal fluorides into the solid electrolyte membrane, the capacity retention rate and cycle performance of lithium-ion batteries are significantly improved, thus enhancing the performance of lithium-ion batteries.

[0135] 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 described. However, as long as the combination of these technical features does not contradict each other, it should be considered to be within the scope of this specification.

[0136] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification can be used to interpret the scope of the claims.

Claims

1. A solid electrolyte composite membrane, characterized in that, The solid electrolyte composite membrane is sheet-like; the solid electrolyte composite membrane comprises: a first sulfide solid electrolyte matrix material, and a metal fluoride dispersed in the first sulfide solid electrolyte matrix material, wherein the metal fluoride is blended and bonded with the first sulfide solid electrolyte matrix material, and the metal fluoride fills the pores of the first sulfide solid electrolyte matrix material, the metal fluoride comprising one or more of aluminum fluoride, zirconium fluoride, and lithium fluoride, the first sulfide solid electrolyte matrix material comprising at least Li element, and the mass ratio of the metal fluoride to the first sulfide solid electrolyte matrix material is 1:(15~500).

2. The solid electrolyte composite membrane according to claim 1, characterized in that, The compaction density of the solid electrolyte composite membrane is 85%~95%.

3. The solid electrolyte composite membrane according to claim 1 or 2, characterized in that, The first sulfide solid electrolyte matrix material also includes: Group 6 elements and Group 5 elements.

4. The solid electrolyte composite membrane according to claim 3, characterized in that, The sixth main group element includes one or more of S, Se, and O, and the fifth main group element includes one or more of P and Sb.

5. The solid electrolyte composite membrane according to claim 4, characterized in that, The solid electrolyte composite membrane comprises: (100-xy)Li₂S·xP₂S₅·yM m N n ·zLi a Al b Zr c F d Li 10±v Ge l-g G g P 2-q QS 12-w W w ·zLi a Al b Zr c F d and Li 6±u P 1-e E e S 5±u-r R r X 1±u ·zLi a Al b Zr c F d One or more of the following; Among them, in (100-xy)Li2S·xP2S5·yM m N n ·zLi a Al b Zr c F d In the given information, 0 ≤ x < 100, 0 ≤ y < 100, 0 ≤ x + y < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more of Li, Ge, Si, Sn and Sb, N is selected from one or more of Se, O, Cl, Br and I, 0.01 ≤ z < 50, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, d = a + 3b + 4c; In Li 10±v Ge 1-g G g P 2-q QS 12-w W w ·zLi a Al b Zr c F d In the given information, 0 ≤ v < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is Si and / or Sn, Q is Sb, W is one or more of O, Se, Cl, Br, and I, 0.002 ≤ z < 2, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, and d = a + 3b + 4c. In Li 6±u P 1-e E e S 5±u-r R r X 1±u ·zLi a Al b Zr c F d In the given information, 0 ≤ u < 1, 0 ≤ e < 1, 0 ≤ r < 1, E is one or more of Ge, Si, Sn, and Sb, R is O and / or Se, X is one or more of Cl, Br, and I, 0.001 ≤ z < 1, 0 ≤ a ≤ 3, 0 ≤ b ≤ 1, 0 ≤ c ≤ 1, and d = a + 3b + 4c.

6. The solid electrolyte composite membrane according to claim 1 or 2, characterized in that, The room temperature ionic conductivity of the solid electrolyte composite membrane is 1×10⁻⁶. 6 S / cm ~ 1×10- 1 S / cm, room temperature electronic conductivity is 1×10⁻⁻⁶ 12 S / cm ~1×10- 7 S / cm.

7. A method for preparing a solid electrolyte composite membrane as described in any one of claims 1 to 6, characterized in that, include: A pre-fabricated sheet-like diaphragm is prepared by mixing powder of a second sulfide electrolyte matrix material and powder of a fluorine-containing compound and pressing them into tablets. The prefabricated sheet membrane is sintered, causing the second sulfide electrolyte matrix material and the fluorine-containing compound in the prefabricated sheet membrane to undergo an in-situ solid-phase reaction, generating the metal fluoride and the first sulfide solid electrolyte matrix material. The metal fluoride and the first sulfide solid electrolyte matrix material are blended and bonded together, and the metal fluoride fills the pores of the first sulfide solid electrolyte matrix material.

8. The preparation method according to claim 7, characterized in that, The fluorinated compounds include one or more of NH4F, NH4AlF4 and (NH4)3ZrF7.

9. The preparation method according to claim 7, characterized in that, The second sulfide electrolyte matrix material includes: (100-xy)Li2S·xP2S5·yM m N n Li 10±v Ge l-g G g P 2-q QS 12-w W w and Li 6±u P 1-e E e S 5±u-r R r X 1±u One or more of the following; Among them, in (100-xy)Li2S·xP2S5·yM m N n In this context, 0 ≤ x < 100, 0 ≤ y < 100, 0 ≤ x + y < 100, 0 ≤ m < 4, 0 ≤ n < 6, M is selected from one or more of Li, Ge, Si, Sn and Sb, and N is selected from one or more of Se, O, Cl, Br and I; In Li 10±v Ge 1-g G g P 2-q QS 12-w W w In this context, 0 ≤ v < 1, 0 ≤ g ≤ 1, 0 ≤ q ≤ 2, 0 ≤ w < 1, G is Si and / or Sn, Q is Sb, and W is one or more of O, Se, Cl, Br, and I. In Li 6±u P 1-e E e S 5±u-r R r X 1±u In this context, 0 ≤ u < 1, 0 ≤ e < 1, 0 ≤ r < 1, E is one or more of Ge, Si, Sn, and Sb, R is O and / or Se, and X is one or more of Cl, Br, and I.

10. The preparation method according to claim 7, characterized in that, The mass ratio of the fluorine-containing compound powder to the powder of the second sulfide electrolyte matrix material is 1:(10~200).

11. The preparation method according to any one of claims 7 to 10, characterized in that, The tablet compression pressure is 1 MPa to 720 MPa, and the compression time is 0.1 min to 30 min.

12. The preparation method according to any one of claims 7 to 10, characterized in that, The sintering temperature is 30℃~500℃, and the time is 0.5h~48h.

13. A solid-state battery, characterized in that, include: A positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is a solid electrolyte composite separator as described in any one of claims 1 to 6.

14. A battery module, characterized in that, include: A plurality of lithium-ion batteries electrically connected, wherein at least one lithium-ion battery is a solid-state battery as described in claim 13.

15. An electrical appliance, characterized in that, include: The solid-state battery as described in claim 13 or the battery module as described in claim 14.