Halide electrolyte with core-shell structure, preparation method and solid-state battery

Abstract

The embodiment of the invention provides a halide electrolyte with a core-shell structure, a preparation method and a solid-state battery. The halide electrolyte with the core-shell structure comprises an inner core and a coating layer coating the surface of the inner core. Wherein the inner core is a crystalline halide electrolyte, the coating layer is an amorphous sulfide electrolyte, and the amorphous sulfide electrolyte comprises LiBr, LiI and Li3PS4. According to the scheme, the conductivity and the air stability of the halide electrolyte with the core-shell structure are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a halide electrolyte with core-shell structure, a preparation method and a solid-state battery. BACKGROUND

[0002] Due to the high safety of solid-state electrolytes, the manufacturing packaging process is greatly simplified, and the energy density, reliability and design freedom of the battery are improved, so in various new battery systems, it has become the closest next-generation battery technology to industrialization.

[0003] At present, halide electrolytes such as Li2ZrCl6 (Zr-based) and Li3InCl6 (In-based) are electrolyte materials that have attracted attention in recent years, and their oxidation potentials are higher than those of sulfides, which are theoretically more compatible with positive electrodes. However, the chloride ions in halide electrolytes are prone to hydrolysis reaction with moisture in the air, generating corrosive HCl gas and destroying the crystal structure, thereby reducing the conductivity, resulting in poor air stability of halide electrolytes. SUMMARY

[0004] The present application provides a halide electrolyte with core-shell structure, a preparation method and a solid-state battery, which can improve the air stability of the halide electrolyte.

[0005] In a first aspect, the present application provides a halide electrolyte with core-shell structure, comprising:

[0006] a core and a coating layer coated on the surface of the core;

[0007] The core is a crystalline halide electrolyte;

[0008] The coating layer is an amorphous sulfide electrolyte, and the amorphous sulfide electrolyte comprises LiBr, LiI and Li3PS4.

[0009] In one possible implementation, the chemical formula of the amorphous sulfide electrolyte is 0.15LiBr·0.1LiI·0.375Li3PS4.

[0010] In one possible implementation, the chemical formula of the crystalline halide electrolyte is Li 3-y In 1- y Zr y Cl 5.4 F 0.6 , 0.05≤y≤1.

[0011] In a possible implementation, the mass ratio between the amorphous sulfide electrolyte and the crystalline halide electrolyte is ≤1:10 and ≥1:100.

[0012] In a second aspect, the embodiments of the present application provide a preparation method of the core-shell structure halide electrolyte, for preparing the core-shell structure halide electrolyte as described in the first aspect and / or various possible implementation manners of the first aspect, and the method comprises:

[0013] Li2S, P2S5, LiBr and LiI are ball-milled to obtain first electrolyte coarse powder;

[0014] The first electrolyte coarse powder is refined to obtain sulfide electrolyte fine powder;

[0015] LiCl, InCl3 and ZrF4 are prepared by precursor mixing to obtain halide precursor;

[0016] The halide precursor is heat-treated to obtain second electrolyte coarse powder after cooling;

[0017] The second electrolyte coarse powder is refined to obtain halide electrolyte fine powder;

[0018] The sulfide electrolyte fine powder and the halide electrolyte fine powder are ball-milled to obtain target electrolyte precursor;

[0019] The target electrolyte precursor is heat-treated to obtain the core-shell structure halide electrolyte after cooling.

[0020] In a possible implementation, the ball-milling of Li2S, P2S5, LiBr and LiI to obtain first electrolyte coarse powder comprises:

[0021] The Li2S, the P2S5, the LiBr and the LiI are put into a ball mill tank and sealed;

[0022] The ball mill tank is fixed on a public disc of a vertical planetary ball mill, and the Li2S, the P2S5, the LiBr and the LiI are ball-milled by the vertical planetary ball mill to obtain the first electrolyte coarse powder;

[0023] The ball-to-material ratio is 20:1-40:1, the ball-milling speed is 450-700 rpm, and the ball-milling time is 10-20 hours.

[0024] In a possible implementation, the refining of the first electrolyte coarse powder to obtain sulfide electrolyte fine powder comprises:

[0025] The first electrolyte coarse powder is subjected to multiple times of powdering treatment by a powdering device to obtain the sulfide electrolyte fine powder.

[0026] The processing amount of one-time powdering is 100-150 g, the powdering speed is 25000 r / min, the time length of each powdering is 20-30 seconds, and the powdering times are 8-15 times.

[0027] In a possible implementation, the LiCl, InCl3 and ZrF4 are prepared by precursor mixing to obtain a halide precursor, including:

[0028] The LiCl, the InCl3 and the ZrF4 are subjected to multiple times of powdering treatment by a powdering device to obtain the halide precursor.

[0029] The powdering speed is 25000 r / min, the time length of each powdering is 20-30 seconds, and the powdering times are 6-12 times.

[0030] In a possible implementation, the halide precursor is subjected to heat treatment, and the second electrolyte coarse powder is obtained after cooling, including:

[0031] The halide precursor is transferred to a muffle furnace for heat treatment, and the second electrolyte coarse powder is obtained after cooling.

[0032] The heat treatment temperature is 200-400 ℃, the heating rate is 1-2 ℃ / min, and the holding time is 6-12 hours.

[0033] In a possible implementation, the second electrolyte coarse powder is subjected to refinement treatment to obtain a halide electrolyte fine powder, including:

[0034] The second electrolyte coarse powder is subjected to multiple times of powdering treatment by a powdering device to obtain the halide electrolyte fine powder.

[0035] The powdering speed is 25000 r / min, the time length of each powdering is 20-30 seconds, and the powdering times are 4-8 times.

[0036] In a possible implementation, the sulfide electrolyte fine powder and the halide electrolyte fine powder are prepared by ball milling to obtain a target electrolyte precursor, including:

[0037] The sulfide electrolyte fine powder and the halide electrolyte fine powder are placed in a ball milling tank and sealed.

[0038] Fixing the ball mill jar on the revolving disk of a vertical planetary ball mill, and ball milling the sulfide electrolyte fine powder and the halide electrolyte fine powder by the vertical planetary ball mill to obtain the target electrolyte precursor;

[0039] Among them, the ball-to-material ratio is 10:1-15:1, the ball milling speed is 150-200rpm, the flipping speed is 1-4rpm, and the ball milling time is 2-6 hours.

[0040] In one possible embodiment, the heat treatment of the target electrolyte precursor and the cooling to obtain the core-shell structured halide electrolyte include:

[0041] placing the target electrolyte precursor into a sintering tank and sealing the tank;

[0042] Transferring the sintering pot to a muffle furnace for heat treatment, and obtaining the core-shell structured halide electrolyte after cooling;

[0043] The heat treatment temperature is 150-200°C, the heating rate is 1-2°C / min, and the insulation time is 2-8 hours.

[0044] In a third aspect, an embodiment of the present application provides a solid-state battery, comprising:

[0045] Positive electrode sheet, negative electrode sheet and core-shell structured halide electrolyte;

[0046] The core-shell structured halide electrolyte is the core-shell structured halide electrolyte as shown in the first aspect and / or various possible embodiments of the first aspect, or the core-shell structured halide electrolyte prepared by the second aspect and / or various possible embodiments of the second aspect.

[0047] The core-shell structured halide electrolyte, preparation method and solid-state battery provided in the embodiments of the present application, the core-shell structured halide electrolyte includes a core and a coating layer coated on the surface of the core. Among them, the core is a crystalline halide electrolyte, the coating layer is an amorphous sulfide electrolyte, and the amorphous sulfide electrolyte includes LiBr, LiI and Li3PS4. In this scheme, by utilizing amorphous sulfide to form a dense grain-free coating layer on the surface of the halide electrolyte, water molecules are prevented from penetrating into the core, thereby improving the air stability of the halide electrolyte of the core-shell structure. Moreover, since the amorphous sulfide contains Br and I elements, the penetration of water molecules into the halide electrolyte is further suppressed, the HCl generation rate is reduced, and the conductivity and air stability of the halide electrolyte of the core-shell structure are further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application.

[0049] Figure 1 A flowchart of a method for preparing a core-shell structured halide electrolyte according to the present application.

[0050] The specific embodiments of the application have been shown by way of example in the above-described drawings and will be described in further detail below. These drawings and description are not meant to restrict the scope of the inventive concept in any way but serve to explain the inventive concept to those skilled in the art by way of reference to specific embodiments. DETAILED DESCRIPTION

[0051] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, like reference numerals refer to like elements, unless the context clearly dictates otherwise. The following description of exemplary embodiments is not meant to limit the scope of the application in any way but is merely to illustrate and explain aspects of the application in connection with the accompanying drawings.

[0052] First, the application scenarios involved in the present application are explained:

[0053] In recent years, safety accidents of new energy vehicles have occurred frequently. The core reason is that the flammable organic solvent electrolyte used in traditional lithium ion batteries has significant safety hazards, and conventional improvement methods are difficult to eliminate. In contrast, solid-state lithium ion batteries using solid-state electrolytes have significant advantages in safety. Solid-state electrolytes not only solve the problem of battery safety in essence, but also are expected to greatly simplify the manufacturing and packaging process, and improve the energy density, reliability and design freedom of the battery. As the most promising next-generation technology in various new battery systems, solid-state batteries have become the consensus of the industry and the scientific community. Therefore, it is an urgent need to develop solid-state electrolytes with key characteristics such as high ionic conductivity, high potential, and air stability.

[0054] Currently, the mainstream systems of inorganic solid-state electrolytes include oxides, sulfides, and halides.

[0055] 1. Oxide electrolyte: has a high oxidation potential and can adapt to high-voltage ternary positive electrode materials. However, its ionic conductivity is generally low, and the material is rigid and has poor ductility, resulting in high interface contact impedance with the positive electrode, which restricts the battery performance.

[0056] 2. Sulfide electrolyte: usually has high ionic conductivity and good ductility, which is beneficial to form a dense contact with the electrode, but has the following problems:

[0057] ①、Oxidation potential is relatively low, when the voltage > 3V, easy to produce side reaction, affect the battery performance;

[0058] ②, most of the air stability is poor, exposed to air, it is easy to react with moisture in the air to generate toxic H2S gas, performance sharply;

[0059] ③, a few systems such as Li3PS4 electrolyte air stability is good but its ionic conductivity is low (<1 mS / cm), affect the battery rate performance.

[0060] In short, for various reasons, it is difficult to achieve large-scale mass production.

[0061] 3, halide electrolyte: such as Li2ZrCl6 (Zr based) and Li3InCl6 (In based) is currently concerned about the electrolyte material, the oxidation potential is higher than the sulfide, theoretically more matching the positive electrode, but the halide electrolyte exposed to air, halide electrolyte chloride ion is easy to hydrolysis reaction with moisture in the air, generate corrosive HCl gas and destroy the crystal structure, and then lead to conductivity drop, poor air stability.

[0062] Based on the above problems of halide electrolyte, the technical concept of the present application is as follows: considering the main features of amorphous solid-state electrolyte include high conductivity, no grain boundary characteristics, good mechanical properties and low grain boundary resistance, the amorphous sulfide can be used to form a dense non-grain boundary physical barrier on the surface of halide electrolyte, to block the penetration path of water molecules to halide electrolyte. And, considering that Br and I elements have hydrophobicity, therefore, the amorphous sulfide can contain the above Br and I elements, so as to further inhibit the penetration of water molecules to halide electrolyte, reduce the generation rate of HCl, and thus improve the conductivity and air stability.

[0063] The technical scheme of the present application and how the technical scheme of the present application solves the above technical problems will be described in detail in the following specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes may not be described again in some examples. The embodiments of the present application will be described below with reference to the drawings.

[0064] The present application provides a kind of core-shell structure halide electrolyte, the core-shell structure halide electrolyte includes inner core and cladding layer on the surface of inner core.

[0065] Wherein, inner core is the halide electrolyte of crystalline state, and the chemical formula of the halide electrolyte of crystalline state is Li 3- y In 1-y Zr y Cl 5.4 F0.6 0.05≤y≤1.

[0066] In one possible implementation, when y=0.15, the chemical formula of the crystalline halide electrolyte is Li 2.85 In 0.85 Zr 0.15 Cl 5.4 F 0.6 It has been verified that the ionic conductivity of the core-shell structure halide electrolyte in this implementation is 2.0 mS / cm @ RT.

[0067] wherein the coating layer is an amorphous sulfide electrolyte, and the amorphous sulfide electrolyte comprises LiBr, LiI, and Li3PS4.

[0068] In one specific implementation, the chemical formula of the amorphous sulfide electrolyte is 0.15LiBr·0.1LiI·0.375Li3PS4.

[0069] It should be understood that the chemical formula of the amorphous sulfide electrolyte is hereinafter abbreviated as LPSBI, that is, 0.15LiBr·0.1LiI·0.375Li3PS4 is represented by LPSBI.

[0070] It should be understood that in actual applications, LiBr, LiI, and Li3PS4 can also exist in other proportions in the amorphous sulfide electrolyte, which can be determined according to actual conditions.

[0071] wherein the core-shell structure halide electrolyte can be represented by x%·LPSBI@Li 2.85 In 0.85 Zr 0.15 Cl 5.4 F 0.6 wherein x% is the mass ratio between LPSBI and Li 2.85 In 0.85 Zr 0.15 Cl 5.4 F 0.6 .

[0072] In one possible implementation, the mass ratio between the amorphous sulfide electrolyte and the crystalline halide electrolyte is ≤1:10, and the mass ratio is ≥1:100.

[0073] That is, 1≤x≤10.

[0074] The embodiment of the present application provides a kind of halide electrolyte of core-shell structure, including inner core and the cladding layer of cladding in the surface of inner core.Therein, inner core is the halide electrolyte of crystalline state, cladding layer is the sulfide electrolyte of amorphous state, the sulfide electrolyte of amorphous state includes LiBr, LiI and Li3PS4.In the present scheme, by utilizing amorphous sulfide to form dense no grain boundary cladding layer on the surface of halide electrolyte, the penetration of water molecules to inner core is prevented, the air stability of the halide electrolyte of core-shell structure is improved.And, since amorphous sulfide contains Br element and I element, the penetration of water molecules to the halide electrolyte of inner core is further inhibited, HCl generation rate is reduced, the conductivity and air stability of the halide electrolyte of core-shell structure are improved again.

[0075] The halide electrolyte in prior art has the following technical problems in addition to the problem of poor air stability:

[0076] Problem 1, the ion conductivity is low (≤1 mS / cm): the lithium ion migration channel in the tightly packed halide lattice is narrow, and the high grain boundary resistance further hinders ion diffusion, which seriously limits the battery rate performance.

[0077] Problem 2, the Young's modulus is higher than that of sulfide electrolyte, that is, the hardness is greater than that of sulfide electrolyte, there are problems of poor processability, not easy to mix with positive electrode to form a relatively dense positive electrode cladding layer, which seriously affects the high rate and long cycle performance of the battery.

[0078] In the present application, for problem 1, the structure of amorphous solid electrolyte has a long-range disordered state, there are a large number of defects, which create good conditions for ion transmission, so the conductivity of amorphous solid electrolyte is high. The amorphous sulfide electrolyte is coated outside the crystalline halide electrolyte, which can effectively improve the ion conductivity of the halide electrolyte of core-shell structure. Secondly, amorphous solid electrolyte has no grain boundary characteristics, which helps complete solid-solid contact and uniform lithium ion conduction of high-performance cathode. This characteristic reduces the grain boundary resistance and helps improve the overall performance of the battery.

[0079] For problem 2, amorphous electrolyte has the advantages of softness, easy to manufacture, low grain boundary, wider component variation and isotropic ion conduction. Therefore, the halide electrolyte of core-shell structure using amorphous electrolyte as shell material also has high processability, is easier to mix with positive electrode, and forms a good cladding layer on the surface of positive electrode particles, which is beneficial to the realization of high rate and long cycle performance of the battery.

[0080] That is, the core-shell structured halide electrolyte provided by the present application has an amorphous sulfide electrolyte as the shell material and a crystalline halide electrolyte as the core material. By combining the characteristics of the two and optimizing the coating amount, the core-shell structured halide electrolyte has high ionic conductivity, high oxidation potential, high air stability, and high processability.

[0081] In summary, the core-shell structured halide electrolyte provided by the present application has the following technical effects:

[0082] 1. High ionic conductivity (≥2 mS / cm): conducive to achieving large-rate charge and discharge performance of the battery.

[0083] 2. High oxidation potential (≥4.5 V): by introducing a halide electrolyte with F element doping as the core, the oxidation potential of the core-shell structured halide electrolyte can be effectively improved, and the contact stability with the positive electrode material can be inherently enhanced. Then, an amorphous sulfide electrolyte with lower Young's modulus is used as the shell material (coating layer), which can further improve the contact between the core-shell structured halide electrolyte and the positive active material, further improve the performance of the battery, reduce the generation of side reactions between the electrolyte and the positive electrode material, improve the capacity of the positive active material, and improve the energy density and cycle stability of the battery.

[0084] 3. High air stability: by introducing an amorphous sulfide electrolyte with high air stability as the coating layer, the air stability of the core-shell structured halide electrolyte can be effectively improved, thereby reducing the subsequent electrode preparation environment requirements and manufacturing costs, and making it easier to achieve large-scale production. The ion conductivity retention rate under the condition of -40°C normal dew point drying room exposure for 4 hours is ≥98%, which can realize the preparation of positive electrode dry method or wet method normal dew point drying room, effectively reduce the manufacturing cost, and realize large-scale production.

[0085] 4. Good processability: easy to mix with the positive electrode to form a dense coating layer, improving the high-rate and long-cycle performance of the battery.

[0086] Based on the above-mentioned core-shell structured halide electrolyte, the preparation method for preparing the core-shell structured halide electrolyte is explained next.

[0087] Figure 1 The flowchart of the preparation method of the core-shell structured halide electrolyte provided by the present application is shown in Figure 1 The method can be realized by the following steps:

[0088] S11, ball milling of Li2S, P2S5, LiBr, and LiI to obtain a first electrolyte coarse powder.

[0089] In an embodiment, the entire preparation process needs to be carried out under an inert atmosphere.

[0090] In a possible implementation, Li2S, P2S5, LiBr and LiI can be put into a ball mill jar and sealed. Then the ball mill jar is fixed on the orbiting disc of a vertical planetary ball mill, and Li2S, P2S5, LiBr and LiI are ball milled by the vertical planetary ball mill to obtain the first electrolyte coarse powder.

[0091] The ball-to-material ratio is 20:1-40:1, the ball milling speed is 450-700 rpm, and the ball milling time is 10-20 hours.

[0092] Specifically, Li2S, P2S5, LiBr and LiI are weighed according to the ratio and put into a ball mill jar. After good sealing, a vertical planetary ball mill is used for ball milling preparation.

[0093] It should be understood that a full planetary ball mill can also be used to fully ball mill and mix the four raw materials of Li2S, P2S5, LiBr and LiI without dead angles. Unlike the conventional vertical planetary ball mill, the full planetary ball mill works while the planet main disc rotates continuously at 360° or at any angle, so that the material can fully participate in grinding and mixing, thereby reducing the material sinking phenomenon and achieving the purpose of mixing without dead angles.

[0094] S12, the first electrolyte coarse powder is refined to obtain a sulfide electrolyte fine powder.

[0095] In a possible implementation, the first electrolyte coarse powder is subjected to multiple powdering treatments by a powdering device to obtain a sulfide electrolyte fine powder.

[0096] The processing capacity of each powdering is 100-150 g, the powdering speed is 25000 r / min, the time of each powdering is 20-30 seconds, and the number of powdering is 8-15 times.

[0097] For example, the powdering device can be a DFY-200 powdering device.

[0098] It should be understood that the D90 of the sulfide electrolyte fine powder is approximately 1 μm.

[0099] S13, LiCl, InCl3 and ZrF4 are subjected to precursor mixing preparation to obtain a halide precursor.

[0100] In a possible implementation, LiCl, InCl3 and ZrF4 are subjected to multiple powdering treatments by a powdering device to obtain a halide precursor.

[0101] The powdering speed is 25000 r / min, the powdering time is 20-30 seconds, and the powdering frequency is 6-12 times.

[0102] Specifically, LiCl, InCl3 and ZrF4 are weighed according to the ratio and put into a DFY-200 powdering device for precursor mixing preparation. It should be understood that the ratio is related to the ratio of Li 3-y In 1-y Zr y Cl 5.4 F 0.6 The value of y is related to the value of y.

[0103] S14, heat treating the halide precursor, and obtaining a second electrolyte coarse powder after cooling.

[0104] In one possible implementation, the halide precursor is transferred to a muffle furnace for heat treatment, and a second electrolyte coarse powder is obtained after cooling.

[0105] The heat treatment temperature is 200-400 DEG C, the heating rate is 1-2 DEG C / min, and the holding time is 6-12 hours.

[0106] S15, refining the second electrolyte coarse powder to obtain a halide electrolyte fine powder.

[0107] In one possible implementation, the second electrolyte coarse powder is subjected to multiple powdering treatments by a powdering device to obtain a halide electrolyte fine powder.

[0108] The powdering speed is 25000 r / min, the powdering time is 20-30 seconds, and the powdering frequency is 4-8 times.

[0109] It should be understood that the D50 of the halide electrolyte fine powder is approximately 5 microns.

[0110] S16, ball milling the sulfide electrolyte fine powder and the halide electrolyte fine powder to obtain a target electrolyte precursor.

[0111] In one possible implementation, the sulfide electrolyte fine powder and the halide electrolyte fine powder are put into a ball milling tank and sealed. Then, the ball milling tank is fixed on a public disc of a vertical planetary ball mill, and the sulfide electrolyte fine powder and the halide electrolyte fine powder are ball milled by the vertical planetary ball mill to obtain a target electrolyte precursor.

[0112] The ball-to-material ratio is 10:1-15:1, the ball milling speed is 150-200 rpm, the rotation speed is 1-4 rpm, and the ball milling time is 2-6 hours.

[0113] Specifically, a certain amount of sulfide electrolyte fine powder and halide electrolyte fine powder are taken according to the ratio, put into a ball milling tank, and sealed for omnidirectional ball milling mixing to obtain the target electrolyte precursor.

[0114] The ratio is related to the mass ratio between the amorphous sulfide electrolyte and the crystalline halide electrolyte.

[0115] S17, heat treating the target electrolyte precursor to obtain the halide electrolyte with a core-shell structure after cooling.

[0116] In a possible implementation, the target electrolyte precursor can be put into a sintering tank and sealed. Then, the sintering tank is transferred to a muffle furnace for heat treatment, and the halide electrolyte with a core-shell structure is obtained after cooling.

[0117] The heat treatment temperature is 150-200℃, the heating rate is 1-2℃ / min, and the holding time is 2-8 hours.

[0118] Through low-temperature heat treatment, on the one hand, the amorphous sulfide electrolyte of the coating layer can be converted to a glass-ceramic state, that is, a phase between the amorphous state and the crystalline state, which further improves the structural stability on the basis of the characteristics of the amorphous electrolyte, and then improves the performance of the halide electrolyte with a core-shell structure. On the other hand, the surface coating can be more dense and uniform, and the performance consistency of the halide electrolyte with a core-shell structure can be improved.

[0119] The preparation method of the halide electrolyte with a core-shell structure provided in the embodiments of the present application is used to prepare the halide electrolyte with a core-shell structure shown in any of the above embodiments. The method comprises: ball milling Li2S, P2S5, LiBr, and LiI to obtain first electrolyte coarse powder; then refining the first electrolyte coarse powder to obtain sulfide electrolyte fine powder; then preparing a halide precursor by precursor mixing of LiCl, InCl3, and ZrF4 to obtain a halide precursor; then heat treating the halide precursor to obtain second electrolyte coarse powder after cooling; next, refining the second electrolyte coarse powder to obtain halide electrolyte fine powder; then, ball milling the sulfide electrolyte fine powder and the halide electrolyte fine powder to obtain a target electrolyte precursor; and finally, heat treating the target electrolyte precursor to obtain the halide electrolyte with a core-shell structure after cooling. In the ball milling preparation process, the rotation speed is controlled to be between 1-4rpm, which can effectively prevent the material from sinking to the bottom. Moreover, after omnidirectional ball milling mixing of the sulfide electrolyte fine powder and the halide electrolyte fine powder, low-temperature co-firing is performed, which can form a dense core-shell structure, that is, the coating layer of the halide electrolyte with a core-shell structure.

[0120] Next, the technical effects of the present application are illustrated through several examples and comparative examples.

[0121] Example 1: 1%·LPSBI@ Li 2.85 In 0.85 Zr 0.15 Cl 5.4 F 0.6

[0122] Step 1), under an argon atmosphere, 0.5625 mol of Li2S, 0.1875 mol of P2S5, 0.15 mol of LiBr, and 0.1 mol of LiI were weighed according to the molar ratio and placed in a ball mill jar, the ball-to-material ratio was controlled to be 20:1, after good sealing, a vertical planetary ball mill was used for ball milling preparation, the ball milling speed was 640 rpm, the ball milling time was 12 h, and after the ball milling was completed, the first electrolyte coarse powder was obtained;

[0123] Step 2), the DFY-200 powdering equipment was used for fine processing of the first electrolyte coarse powder, the processing amount was 100 g, the powdering speed was 25000 r / min, the time for each powdering was 30 S, the powdering times was 15 times, and after the end, the sulfide electrolyte fine powder with D90≈1 μm was obtained.

[0124] Step 3), under an argon atmosphere, 2.85 mol of LiCl, 0.85 mol of InCl3, and 0.15 mol of ZrF4 were weighed according to the molar ratio and placed in the DFY-200 powdering equipment for precursor mixing preparation, specifically: the powdering speed was 25000 r / min, the powdering time was 30 S / time, the powdering times was 8 times, and after the end, the halide precursor was obtained.

[0125] Step 4), the halide precursor was transferred to a muffle furnace for low-temperature heat treatment, the sintering temperature was 330℃, the heating rate was 1℃ / min, the holding time was 8 h, and after natural cooling, the second electrolyte coarse powder was obtained.

[0126] Step 5), the DFY-200 powdering equipment was used again for fine processing of the second electrolyte coarse powder, the processing amount was 100 g, the powdering speed was 25000 r / min, the time for each powdering was 20 S, the powdering times was 6 times, and after the end, the halide electrolyte fine powder with D50≈5 μm was obtained.

[0127] Step 6), 100 g of the halide electrolyte fine powder and 1 g of the sulfide electrolyte fine powder were weighed according to the ratio and placed in a ball mill jar, after good sealing, all-directional ball milling was carried out, the ball-to-material ratio was 10:1, the ball milling speed was 180 rpm, the rotation speed was 1 rpm, and the ball milling time was 4 h, and the target electrolyte precursor was obtained.

[0128] Step 7), after the target electrolyte precursor was put into a sealed sintering pot and sealed, it was transferred to a muffle furnace for heat treatment, the heat treatment temperature was 180℃, the heating rate was 1℃ / min, the holding time was 6h, and the core-shell structured halide electrolyte was obtained after natural cooling.

[0129] In Examples 2-13, only the value of x was changed compared with Example 1, and the process flow was the same as Example 1 (but the molar ratio of raw materials was different).

[0130] Comparative Example 1

[0131] Only the coating layer LPSBI was used as a comparative electrolyte.

[0132] Comparative Example 2

[0133] Only the core Li 2.85 In 0.85 Zr 0.15 Cl 5.4 F 0.6 as a comparative electrolyte.

[0134] Exemplarily, the composition of the electrolyte is exemplified by Table 1.

[0135] Table 1 Composition of electrolytes in Examples and Comparative Examples

[0136]

[0137] The above Examples 1-13 and Comparative Examples 1 and 2 were tested for performance, including ion conductivity test, air stability test, voltage window test and battery test.

[0138] Ion conductivity test: 100mg of electrolyte powder (core-shell structured halide electrolyte in Examples 1-13, or comparative electrolyte of Comparative Examples 1 and 2) was weighed and placed in an insulating sleeve with an inner diameter of 10mm, and was pressed into a sheet at a pressure of 300MPa, and an alternating current impedance spectrum test was performed to measure the impedance value of the electrolyte material. The thickness of the pressed sheet electrolyte was then tested, and the ion conductivity of the electrolyte material was calculated according to the formula from the sheet impedance value, thickness value and area. Wherein, σ is the ion conductivity, unit s / cm; d is the sheet thickness, unit cm; R is the impedance value, unit Ω; S is the sheet area, unit cm 2 .

[0139] Air Stability Test: After the ionic conductivity test for the same batch of electrolyte is completed as above, a 100mg sample of electrolyte powder is placed in an environment with a temperature of 25±3°C and a dew point of ≤-55°C for 6 hours. After the idling period, the electrolyte ionic conductivity is retested and the ionic conductivity retention rate is calculated. If the ionic conductivity retention rate is ≥95%, the electrolyte has high air stability.

[0140] Target electrolyte voltage window test: The electrolyte (the core-shell halide electrolyte in Examples 1-13, or the comparative electrolyte in Comparative Examples 1 and 2) and the conductive carbon powder were weighed at a weight ratio of 70:30 and ground evenly using an agate mortar. In an insulating outer cylinder with a diameter of 10 mm, 20 mg of the target electrolyte-conductive carbon powder mixture, 20 mg of Li 5.4 PS 4.4 Cl 1.6 The electrolyte is stacked. It is press-formed at a pressure of 360MPa, and then 5.4 PS 4.4 Cl 1.6 A lithium foil is laminated side-by-side and pressed at a pressure of 100 MPa. Stainless steel current collectors are then placed above and below the laminate, with leads attached to the collectors. Linear sweep voltammetry is performed over a 2-5V range at a scan rate of 0.1mV / s. A tangent line is drawn through the oxidation peak of the test curve, and the intersection with the horizontal axis represents the material's oxidation potential.

[0141] Battery test: In an argon glove box, the electrolyte ((the core-shell halide electrolyte in Examples 1-13, or the comparative electrolyte in Comparative Examples 1 and 2)), the positive electrode active material Li (Ni 0.8 Co 0.1 Mn 0.1 )O2(NCM811) were weighed at a weight ratio of 20:80. They were ground evenly using an agate mortar to prepare a composite positive electrode material. In an insulating outer cylinder with a diameter of 10 mm, 14 mg of the above composite positive electrode material, 70 mg of Li 5.4 PS 4.4 Cl 1.6The electrolyte was stacked. It was press-molded at a pressure of 360 MPa, whereby a positive electrode and a solid electrolyte layer were obtained. Next, an aluminum foil was stacked on the positive electrode side, whereby a current collector was formed on the positive electrode side. Then, an indium sheet having a thickness and a diameter of 200 μm and 10 mm, respectively, was placed as a negative electrode material on the side of the solid electrolyte layer opposite to the side in contact with the positive electrode. It was press-molded at a pressure of 80 MPa, whereby a stack composed of the positive electrode, the solid electrolyte layer, and the negative electrode was produced. Next, stainless steel current collectors were arranged above and below the stack, and current collecting leads were attached to the current collectors. The assembled solid-state battery was subjected to a cycle performance test under the following conditions: a current density of 1 C, and a voltage range of 2.7-4.3 V (Li+ / Li).

[0142] It should be understood that the performance parameters of Examples 1-13 and Comparative Examples 1 and 2 can be represented by Table 2 after the above tests.

[0143] Table 2 Performance parameters of each example and comparative example

[0144]

[0145] In combination with the data in Tables 1 and 2, and Examples 1-13, it can be seen that as the coating amount x% increases, the ionic conductivity of the core-shell structured halide electrolyte and the air stability level show a rising trend, the oxidation potential shows a declining trend, and the battery performance shows a rising and then declining trend. In view of the battery performance, the data of ionic conductivity, oxidation potential, and air stability show that Example 5 has the best effect, at which the battery performance is optimal, and the ionic conductivity, oxidation potential, and air stability are all at a relatively high level. Specifically, the ionic conductivity is 2.50 mS / cm, the oxidation potential is 4.52 V, the battery performance is optimal (first efficiency 95.2%, first-week discharge capacity 210.8 mAh / g, 200-week cycle capacity retention rate 98.5%, and air stability 98.2%).

[0146] As can be seen from Comparative Example 1, the single-shell material, i.e., the amorphous sulfide electrolyte, has relatively high ionic conductivity and air stability, but its oxidation potential is low, causing a large side reaction with the positive electrode and thus poor battery performance. As can be seen from Comparative Example 2, the single-core material, i.e., the crystalline halide electrolyte, has relatively optimal oxidation potential and battery performance, but its ionic conductivity is low and its air stability is poor.

[0147] The application also provides a solid-state battery, comprising a positive electrode sheet, a negative electrode sheet, and a core-shell structured halide electrolyte. The core-shell structured halide electrolyte is the core-shell structured halide electrolyte according to any one of the core-shell structured halide electrolyte embodiments or is prepared by the preparation method of any one of the core-shell structured halide electrolyte embodiments.

[0148] It should be understood, however, that the specific forms of the application herein illustrated and described are not intended to limit the application thereto. Accordingly, the application is to be considered as embracing any and all modifications of the form of the application which lie within the principles of the application and the scope of the appended claims.

Claims

1. A core-shell structured halide electrolyte, characterized in that: include: A core and a coating layer coated on the surface of the core; The core is a crystalline halide electrolyte; The coating layer is an amorphous sulfide electrolyte, and the amorphous sulfide electrolyte includes LiBr, LiI and Li3PS4.

2. The core-shell halide electrolyte according to claim 1, characterized in that The chemical formula of the amorphous sulfide electrolyte is 0.15LiBr·0.1LiI·0.375Li3PS4.

3. The core-shell halide electrolyte according to claim 1 or 2, characterized in that The chemical formula of the crystalline halide electrolyte is Li 3-y In 1-y Zr y Cl 5.4 F 0.6 , 0.05≤y≤1.

4. The core-shell halide electrolyte according to claim 1 or 2, characterized in that The mass ratio of the amorphous sulfide electrolyte to the crystalline halide electrolyte is ≤1:10, and the mass ratio is ≥1:

100.

5. A method for preparing a core-shell structured halide electrolyte, for preparing the core-shell structured halide electrolyte according to any one of claims 1 to 4, the method comprising: Ball milling Li2S, P2S5, LiBr and LiI to obtain a first electrolyte coarse powder; Refining the first electrolyte coarse powder to obtain sulfide electrolyte fine powder; Preparing a precursor mixture of LiCl, InCl3 and ZrF4 to obtain a halide precursor; heat-treating the halide precursor and obtaining a second electrolyte coarse powder after cooling; performing a refining treatment on the second electrolyte coarse powder to obtain a halide electrolyte fine powder; ball milling the sulfide electrolyte fine powder and the halide electrolyte fine powder to obtain a target electrolyte precursor; The target electrolyte precursor is heat-treated and cooled to obtain the core-shell structured halide electrolyte.

6. The method according to claim 5, characterized in that The process of ball milling Li2S, P2S5, LiBr and LiI to obtain a first electrolyte coarse powder comprises: Put the Li2S, P2S5, LiBr and LiI into a ball mill jar and seal it; Fixing the ball mill jar on the revolving disk of a vertical planetary ball mill, and ball milling the Li2S, P2S5, LiBr and LiI by the vertical planetary ball mill to obtain the first electrolyte coarse powder; Among them, the ball-to-material ratio is 20:1-40:1, the ball milling speed is 450-700rpm, and the ball milling time is 10-20 hours.

7. The method according to claim 5 or 6, characterized in that The refining treatment of the first electrolyte coarse powder to obtain sulfide electrolyte fine powder comprises: performing multiple pulverizing treatments on the first electrolyte coarse powder by a pulverizing device to obtain the sulfide electrolyte fine powder; Among them, the processing capacity of one powdering is 100-150g, the powdering speed is 25000r / min, the duration of each powdering is 20-30 seconds, and the number of powdering times is 8-15 times.

8. The method according to claim 5 or 6, characterized in that The method of preparing a precursor mixture of LiCl, InCl3 and ZrF4 to obtain a halide precursor comprises: Performing multiple powdering treatments on the LiCl, the InCl3, and the ZrF4 by a powdering device to obtain the halide precursor; Among them, the powdering speed is 25000r / min, the duration of each powdering is 20-30 seconds, and the number of powdering times is 6-12 times.

9. The method according to claim 5 or 6, characterized in that The heat treatment of the halide precursor and the cooling to obtain a second electrolyte coarse powder comprises: transferring the halide precursor to a muffle furnace for heat treatment, and obtaining the second electrolyte coarse powder after cooling; The heat treatment temperature is 200-400°C, the heating rate is 1-2°C / min, and the insulation time is 6-12 hours.

10. The method according to claim 5 or 6, characterized in that The refining treatment of the second electrolyte coarse powder to obtain halide electrolyte fine powder comprises: The second electrolyte coarse powder is subjected to multiple pulverizing treatments by a pulverizing device to obtain the halide electrolyte fine powder; Among them, the powdering speed is 25000r / min, the duration of each powdering is 20-30 seconds, and the number of powdering times is 4-8 times.

11. The method according to claim 5 or 6, characterized in that The process of ball milling the sulfide electrolyte fine powder and the halide electrolyte fine powder to obtain a target electrolyte precursor comprises: Putting the sulfide electrolyte fine powder and the halide electrolyte fine powder into a ball milling jar and sealing the jar; Fixing the ball mill jar on the revolving disk of a vertical planetary ball mill, and ball milling the sulfide electrolyte fine powder and the halide electrolyte fine powder by the vertical planetary ball mill to obtain the target electrolyte precursor; Among them, the ball-to-material ratio is 10:1-15:1, the ball milling speed is 150-200rpm, the flipping speed is 1-4rpm, and the ball milling time is 2-6 hours.

12. The method according to claim 5 or 6, characterized in that The target electrolyte precursor is subjected to heat treatment, and after cooling, the core-shell structured halide electrolyte is obtained, comprising: placing the target electrolyte precursor into a sintering tank and sealing the tank; Transferring the sintering pot to a muffle furnace for heat treatment, and obtaining the core-shell structured halide electrolyte after cooling; The heat treatment temperature is 150-200°C, the heating rate is 1-2°C / min, and the insulation time is 2-8 hours.

13. A solid-state battery, characterized in that: Including a positive electrode sheet, a negative electrode sheet and a halide electrolyte with a core-shell structure; The core-shell structured halide electrolyte is the core-shell structured halide electrolyte according to any one of claims 1 to 4, or the core-shell structured halide electrolyte prepared by the method for preparing the core-shell structured halide electrolyte according to any one of claims 5 to 12.

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