A halide oxyde electrolyte, method of preparation and battery

Abstract

A halogen oxide electrolyte, its preparation method, and a battery are disclosed, relating to the field of electrolyte technology. The general chemical formula of the halogen oxide electrolyte is Li. 2+a+b Zr 1‑a Fe a Cl 6‑b O b Where the value of a ranges from 0 to a ≤ 0.4 and the value of b ranges from 0 to b ≤ 0.1, this preparation method is used to prepare the aforementioned oxide electrolyte. By controlling the doping amount of Fe and O elements, the two can produce a synergistic effect, which can significantly improve the ionic conductivity of the prepared halide oxide electrolyte and optimize the interface stability with the electrode. The preparation process is easy to control and is conducive to improving the preparation efficiency.

Description

Technical Field

[0001] This invention relates to the field of electrolyte technology, and in particular to a halide oxide electrolyte, its preparation method, and a battery. Background Technology

[0002] LZC halide electrolyte (Li2ZrCl6) has been widely used due to its low raw material cost, certain tolerance to air humidity, and high oxidation stability. However, LZC halide electrolyte has low ionic conductivity at room temperature. When it is used in batteries, it may result in low rate capability and failure to meet battery performance requirements. Therefore, it is necessary to dope and modify LZC halide electrolyte.

[0003] The common doping method is to improve the stability of LZC halide electrolytes by doping with oxygen. However, oxygen doping can disturb the lithium ion migration path, which may block the lithium ion migration channel and thus fail to improve the ionic conductivity, limiting the application of LZC halide electrolytes. Summary of the Invention

[0004] The purpose of this invention is to provide a halide oxide electrolyte, a preparation method, and a battery. By controlling the doping amounts of Fe and O elements, a synergistic effect can be achieved between the two, which can significantly improve the ionic conductivity of the prepared halide oxide electrolyte and optimize the interfacial stability with the electrode. The preparation process is easy to control and is conducive to improving preparation efficiency.

[0005] This invention provides a halide oxide electrolyte with the general chemical formula Li. 2+a+b Zr 1-a Fe a Cl 6-b O b , where the range of values ​​for a is 0 < a ≤ 0.4, and the range of values ​​for b is 0 < b ≤ 0.1.

[0006] In one embodiment, the value of a is in the range of 0.1≤a≤0.25, and / or the value of a is 0.1, 0.15, 0.25 or 0.3.

[0007] In one embodiment, the value of b is in the range of 0 < b ≤ 0.08, and / or the value of b is in the range of 0.02 ≤ b ≤ 0.05, and / or the value of b is 0.02, 0.04, 0.05 or 0.08.

[0008] In one embodiment, the ratio c of the doping amount of O element to the doping amount of Fe element is in the range of 0.08≤c≤0.5.

[0009] In one embodiment, the chemical formula is Li2. 29Zr0. 75 Fe0. 25 Cl5. 96 O0. 04 Li2. 20 Zr0. 85 Fe0. 15 Cl5. 95 O0. 05 Li2. 12 Zr0.9Fe0.1Cl5. 98 O0. 02 And Li2. 38 Zr0.7Fe0.3Cl5. 92 O0. 08 At least one of them.

[0010] This invention also proposes a method for preparing a halide oxide electrolyte, comprising the following steps: Raw material preparation: Under an inert atmosphere, lithium source, zirconium source, chlorine source, iron source and oxygen source were weighed according to stoichiometric ratio to obtain the first mixture; Ball milling treatment: The first mixture was ball milled under an inert atmosphere to obtain an electrolyte precursor; Heat treatment: The electrolyte precursor is heat-treated under an inert atmosphere to obtain the finished electrolyte product.

[0011] In one embodiment, the lithium source is LiCl, and / or the zirconium source is ZrCl4, and / or the iron source is FeCl3, and / or the oxygen source is Li2O.

[0012] In one embodiment, the following steps are also included: Raw material pretreatment: Under vacuum or inert atmosphere protection, at least one of the lithium source, zirconium source, iron source and oxygen source is heated or dried.

[0013] In one embodiment, the following steps are also included: Grinding and sieving: Under an inert atmosphere, the electrolyte product is ground and sieved to obtain the target electrolyte.

[0014] The present invention also proposes a battery comprising the aforementioned halide electrolyte, or comprising a halide electrolyte prepared by the aforementioned method for preparing halide electrolyte.

[0015] The beneficial effects of this invention are as follows: In the halide oxide electrolyte proposed in this invention, parameter a can characterize the degree of substitution of Fe element for Zr element, and parameter b can characterize the degree of substitution of O element for Cl element. By controlling the value range of parameters a and b, the doping amount of Fe element and O element can be controlled, so that the two can produce a synergistic effect, thereby significantly improving the ionic conductivity of the prepared halide oxide electrolyte. When the halide oxide electrolyte of this invention is applied to the battery, it can also optimize the interface stability with the electrode, especially the interface stability with the lithium metal anode, so as to ensure ion conduction performance and improve electrochemical stability. The appropriate doping of oxygen (O) in combination with appropriate doping of fe (Fe) effectively suppressed the negative effects of oxygen on LZC halide electrolytes. This was achieved by fully utilizing the oxygen... 2- The high electronegativity of Fe induces the formation of a more stable and lower impedance passivation layer, which significantly improves the dynamics of the electrolyte or negative electrode interface, optimizes the interface characteristics, and has little disturbance to the bulk lattice structure of the electrolyte. This also ensures the quality of Fe doping in improving conductivity and is beneficial to optimizing the microstructure of LZC halide electrolytes. By controlling and doping with trace amounts of oxygen, the interface stability can be optimized, and the problems of oxygen altering and damaging the lithium ion site and migration path can be effectively avoided, thus preventing the blockage of lithium ion migration channels. In the low-O doping range, the main crystal structure of the halide oxide electrolyte can be maintained as the hexagonal close-packed phase or cubic close-packed phase of Li2ZrCl6. Low-O doping combined with Fe doping can finely adjust the lattice parameters of Li2ZrCl6, thereby giving full play to the advantage of Fe in improving ionic conductivity. The resulting halide oxide electrolyte can maintain high ionic conductivity at room temperature (e.g., 25°C), thus obtaining a halide oxide electrolyte that balances high ionic conductivity and excellent interface stability. The doped Fe and O elements are abundant and inexpensive, and are easy to control in the preparation process of the halide oxide electrolyte of the present invention, which is beneficial to improving the preparation efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of a preparation method according to an embodiment of the present invention.

[0018] Figure 2This is a schematic flowchart of a preparation method according to another embodiment of the present invention.

[0019] Figure 3 This is a schematic flowchart of a preparation method according to another embodiment of the present invention.

[0020] Figure 4 This is another schematic diagram of the preparation method according to yet another embodiment of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. Based on the description of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0022] Unless otherwise explicitly specified and limited, the terms "setup," "installation," and "connection" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of these terms based on the specific circumstances.

[0023] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0024] The terms “first,” “second,” “third,” etc., are used merely to distinguish elements with similar properties, not to indicate or imply relative importance or a specific order.

[0025] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0026] The general chemical formula of the halide oxide electrolyte proposed in this invention is Li. 2+a+b Zr 1-a Fe a Cl 6-b O b , where the range of values ​​for a is 0 < a ≤ 0.4, and the range of values ​​for b is 0 < b ≤ 0.1.

[0027] In the halide oxide electrolyte proposed in this invention, parameter a can characterize the degree of substitution of Fe element for Zr element, and parameter b can characterize the degree of substitution of O element for Cl element. By controlling the value range of parameters a and b, the doping amount of Fe element and O element can be controlled, so that the two can produce a synergistic effect, thereby significantly improving the ionic conductivity of the prepared halide oxide electrolyte. When the halide oxide electrolyte of this invention is applied to the battery, it can also optimize the interface stability with the electrode, especially the interface stability with the lithium metal anode, so as to ensure ion conduction performance and improve electrochemical stability. The appropriate doping of oxygen (O) in combination with appropriate doping of fe (Fe) effectively suppressed the negative effects of oxygen on LZC halide electrolytes. This was achieved by fully utilizing the oxygen... 2- The high electronegativity of Fe induces the formation of a more stable and lower impedance passivation layer, which significantly improves the dynamics of the electrolyte or negative electrode interface, optimizes the interface characteristics, and has little disturbance to the bulk lattice structure of the electrolyte. This also ensures the quality of Fe doping in improving conductivity and is beneficial to optimizing the microstructure of LZC halide electrolytes. By controlling and doping with trace amounts of oxygen, the interface stability can be optimized, and the problems of oxygen altering and damaging the lithium ion site and migration path can be effectively avoided, thus preventing the blockage of lithium ion migration channels. In the low-O doping range, the main crystal structure of the halide oxide electrolyte can be maintained as the hexagonal close-packed phase or cubic close-packed phase of Li2ZrCl6. Low-O doping combined with Fe doping can finely adjust the lattice parameters of Li2ZrCl6, thereby giving full play to the advantage of Fe in improving ionic conductivity. The resulting halide oxide electrolyte can maintain high ionic conductivity at room temperature (e.g., 25°C), thus obtaining a halide oxide electrolyte that balances high ionic conductivity and excellent interface stability. The doped Fe and O elements are abundant and inexpensive, and are easy to control in the preparation process of the halide oxide electrolyte of the present invention, which is beneficial to improving the preparation efficiency.

[0028] In one example, the general chemical formula of the halide oxide electrolyte of the present invention is Li. 2+a+b Zr 1-a Fe a Cl 6-b O b The Fe in it is in the positive trivalent state.

[0029] In one example, the value range of parameter a in the general chemical formula of the halide oxide electrolyte of the present invention is preferably 0.1 ≤ a ≤ 0.25.

[0030] Within this range, the amount of Fe doping can be matched with the amount of O doping to ensure that O does not change the migration path of lithium ions, thus giving the prepared halide oxide electrolyte the best ionic conductivity, and to improve the interfacial stability and cycle life with the lithium metal anode, so that the prepared all-solid-state battery has good capacity retention and rate performance.

[0031] For example, the specific value of parameter a can be 0.1, 0.15, 0.25 or 0.3.

[0032] In one example, the value range of parameter b in the general chemical formula of the halide oxide electrolyte of the present invention is preferably 0 < b ≤ 0.08, specifically 0.02 ≤ b ≤ 0.05.

[0033] Within this range, the amount of Fe doping can be matched with the amount of O doping to ensure that O does not change the migration path of lithium ions, thus giving the prepared halide oxide electrolyte the best ionic conductivity, and to improve the interfacial stability and cycle life with the lithium metal anode, so that the prepared all-solid-state battery has good capacity retention and rate performance.

[0034] For example, the specific value of parameter b can be 0.02, 0.04, 0.05 or 0.08.

[0035] In one example, the doping ratio c of O to Fe is in the range of 0.08 ≤ c ≤ 0.5.

[0036] Within this range, the amount of Fe doping can be matched with the amount of O doping to ensure that O does not change the migration path of lithium ions, thus giving the prepared halide oxide electrolyte the best ionic conductivity, and to improve the interfacial stability and cycle life with the lithium metal anode, so that the prepared all-solid-state battery has good capacity retention and rate performance.

[0037] like Figure 1 As shown, this invention proposes a method for preparing a halide oxide electrolyte, specifically comprising the following steps: Raw material preparation: Under an inert atmosphere, lithium source, zirconium source, chlorine source, iron source and oxygen source were weighed according to stoichiometric ratio to obtain the first mixture; Ball milling: The first mixture was ball milled under an inert atmosphere to obtain an electrolyte precursor; Heat treatment: The electrolyte precursor is heat-treated under an inert atmosphere to obtain the finished electrolyte product.

[0038] In one example, the aforementioned raw material preparation steps further include: using Li 2+a+b Zr 1-a Fea Cl 6-b O b The stoichiometric ratio of lithium source, zirconium source, chlorine source, iron source and oxygen source is weighed out, wherein the value of a is in the range of 0 < a ≤ 0.4, preferably 0.1 ≤ a ≤ 0.25, the value of b is in the range of 0 < b ≤ 0.1, preferably 0 < b ≤ 0.08, and further preferably 0.02 ≤ b ≤ 0.05.

[0039] In one example, the aforementioned raw material preparation steps further include: the ratio c of the doping amount of oxygen source to the doping amount of iron source is in the range of 0.08≤c≤0.5.

[0040] In one example, the aforementioned raw material preparation steps further include: a lithium source of LiCl, and / or a zirconium source of ZrCl4, and / or an iron source of FeCl3, and / or an oxygen source of Li2O. This selection ensures both high activity of the raw materials and uniform mixing among them.

[0041] For example, the raw materials used in the aforementioned raw material preparation steps are LiCl, ZrCl4, FeCl3, and Li2O. This selection ensures both high activity of the raw materials and uniform mixing among them.

[0042] For example, the raw materials in the aforementioned raw material preparation steps are weighed using an analytical balance with an accuracy of 0.1 mg.

[0043] In one example, the aforementioned ball milling process further includes: placing the first mixture into a ball milling apparatus for ball milling.

[0044] For example, the ball milling equipment is a high-energy ball mill jar or a planetary high-energy ball mill.

[0045] For example, the rotation speed of the ball milling equipment is 350 rpm to 750 rpm to ensure that the oxygen source can be evenly dispersed and fully mixed with other raw materials. This ensures complete reaction while avoiding the introduction of excessive impurities, thus guaranteeing the quality of ball milling.

[0046] For example, the ball milling time is 10h to 15h to ensure that the oxygen source can be evenly dispersed with other raw materials and that the raw materials can be fully mixed. This ensures that the reaction is complete while avoiding the introduction of too many impurities and thus guarantees the quality of ball milling.

[0047] For example, the high-energy ball mill jar or planetary high-energy ball mill and the grinding balls are made of inert materials, such as ZrO2 or hardened stainless steel.

[0048] For example, the grinding balls have diameters of 5 mm and 10 mm. Mixing grinding balls of two different diameters to ball mill the raw materials helps to improve the ball milling efficiency and also helps to ensure uniform contact between the raw materials.

[0049] For example, the ratio of the mass of the grinding balls to the total mass of the first mixture is 15:1 to 20:1.

[0050] For example, the ball milling equipment is in the mode of intermittent ball milling, which can avoid the ball milling equipment from overheating and affecting the ball milling quality. That is, after the ball milling process is completed for the first time t1, the ball milling equipment is paused for the second time t2, and then the ball milling process is continued for the first time t1. This process is repeated to achieve intermittent ball milling.

[0051] Furthermore, the first time interval t1 is 30 minutes, and the second time interval t2 is 15 minutes.

[0052] In one example, the aforementioned ball milling process further includes: adjusting the parameters of the ball milling equipment to set the rotation speed of the ball milling equipment to 250 rpm / min to 750 rpm / min.

[0053] In one example, the aforementioned ball milling process further includes: pre-drying the ball milling equipment and then placing the first mixture into the ball milling equipment for ball milling.

[0054] In one example, the aforementioned ball milling step further includes cooling the electrolyte precursor to room temperature under an inert atmosphere. This yields a uniform, amorphous, or microcrystalline electrolyte precursor powder.

[0055] For example, the aforementioned ball milling process further includes transferring the milling jar to an inert atmosphere glove box for static cooling, thereby cooling the electrolyte precursor to room temperature. This yields a uniform, amorphous, or microcrystalline electrolyte precursor powder.

[0056] In one example, the aforementioned heat treatment step further includes a heat treatment temperature of 250°C to 350°C. This treatment can eliminate stress between the raw materials, stabilize the crystal structure, and effectively prevent oxygen segregation or the formation of impurity phases at high temperatures.

[0057] In one example, the aforementioned heat treatment step further includes a heat treatment time of 5 to 10 hours. This treatment can eliminate stress between the raw materials, stabilize the crystal structure, and effectively prevent oxygen segregation or the formation of impurity phases at high temperatures.

[0058] In one example, the aforementioned heat treatment step further includes: placing the electrolyte precursor in a sintering container and heating or drying it using a heat treatment device.

[0059] For example, the heat treatment equipment is subjected to repeated vacuum treatment (e.g., 10). -2 (MPa), and repeatedly purged with inert gas (e.g., at least three times) to ensure that the atmosphere inside the heat treatment equipment remains pure.

[0060] For example, the sintering container can be an inert material such as a corundum (Al2O3) crucible or a quartz boat.

[0061] For example, the heat treatment equipment may be a tube furnace or a vacuum furnace.

[0062] For example, during the heat treatment process, an inert gas (e.g., argon) is maintained in a slightly positive pressure flow state. Further, the flow rate of the inert gas is 20 sccm to 50 sccm.

[0063] In one example, the aforementioned heat treatment steps further include: Heating phase: The temperature in the heat treatment equipment is increased to the target temperature at a rate of 2℃ / min to 5℃ / min. Such a slow heating helps to release residual stress and promote uniform crystallization, thus stabilizing the crystal structure.

[0064] The heat preservation stage involves a target temperature range of 250℃ to 350℃, with a preferred target temperature of 300℃, and a heat preservation time of 5 to 10 hours. This process stabilizes the crystal structure, achieves uniform crystallization, and enables the formation of a well-crystallized single-phase Li. 2+a+b Zr 1- a Fe a Cl 6-b O b The finished halide oxide electrolyte product.

[0065] Cooling stage: After the heat preservation stage, the finished electrolyte product is allowed to cool naturally to room temperature. This effectively avoids the generation of internal stress or cracks, ensuring the quality of the finished electrolyte product.

[0066] Sampling: After the temperature in the heat treatment equipment has completely dropped to room temperature, the heat-treated electrolyte product is taken out under the protection of continuous inert gas, or the electrolyte product is transferred to the sample chamber connected to the glove box to avoid contact with air, and then the heat-treated electrolyte product is taken out.

[0067] In one embodiment, such as Figure 2 As shown, the preparation method of halide oxide electrolyte proposed in this invention further includes the following steps: Raw material pretreatment: Under vacuum or inert atmosphere protection, at least one of the lithium source, zirconium source, chlorine source, iron source and oxygen source is heated or dried.

[0068] By anhydrous treatment of at least one of the lithium source, zirconium source, chlorine source, iron source and oxygen source, the physically adsorbed water or crystal water of at least one of the raw materials can be effectively removed, thereby keeping at least one of the raw materials dry and ensuring that the crystal structure is uniform and stable during the preparation process.

[0069] In one example, the aforementioned raw material pretreatment step further includes: placing at least one of the lithium source, zirconium source, chlorine source, iron source and oxygen source into a pretreatment device for heating or drying.

[0070] For example, the pretreatment equipment is a vacuum drying oven.

[0071] In one example, the aforementioned raw material pretreatment step further includes: performing dynamic vacuum drying on at least one of the lithium source, zirconium source, chlorine source, iron source and oxygen source within a temperature range of 120°C to 150°C.

[0072] In one example, the aforementioned raw material pretreatment step further includes: heating or drying for ≥24 hours.

[0073] In one example, the aforementioned raw material pretreatment step further includes: cooling at least one of the heated or dried lithium source, zirconium source, chlorine source, iron source and oxygen source to room temperature in a pretreatment device under an inert atmosphere.

[0074] In one embodiment, combined with Figure 3 and Figure 4 The method for preparing halide oxide electrolytes proposed in this invention further includes the following steps: Grinding and sieving: Under the protection of an inert atmosphere, the electrolyte product is ground and sieved to obtain the target electrolyte.

[0075] In one example, the aforementioned sieving step further includes grinding the electrolyte product in a grinding device. The grinding process enables the electrolyte product to be broken into particles, ultimately obtaining a target electrolyte with a uniform particle size distribution.

[0076] For example, the grinding equipment is an agate mortar or a planetary ball mill.

[0077] In one example, the aforementioned sieving step further includes sieving the finished electrolyte product after grinding using sieving equipment. Sieving removes large particles and agglomerates from the finished electrolyte product, thereby ensuring a uniform particle size distribution of the target electrolyte.

[0078] For example, the sieving equipment uses a standard dividing sieve. Further, the standard dividing sieve has a specification of 400 mesh and an aperture of approximately 38 μm.

[0079] In one example, after sieving the electrolyte product, the resulting target electrolyte is sealed and stored. For example, it is stored in a glass bottle filled with argon gas or a special sample bag, and then placed in a dry environment (such as a glove box) for later use.

[0080] In one example, the inert atmosphere protection mentioned in this invention can be argon.

[0081] In one example, the inert atmosphere protection mentioned in this invention can be carried out in an inert atmosphere glove box.

[0082] For example, the water content and oxygen content of the inert atmosphere glove box are <0.1ppm and <0.1ppm, respectively.

[0083] To facilitate understanding of the halide oxide electrolyte and its preparation method proposed in this invention, further explanation is provided below with reference to various embodiments.

[0084] Example 1: In this embodiment, a=0.25, b=0.04, and the prepared molecular formula is Li2. 29 Zr0. 75 Fe0. 25 Cl5. 96 O0. 04 Halogen oxide electrolytes.

[0085] In the raw material pretreatment step, LiCl and ZrCl4 are continuously dried in a vacuum drying oven at 120°C under dynamic vacuum (<10Pa) for 48 hours to remove physically adsorbed water and water of crystallization.

[0086] In the raw material preparation step, LiCl, ZrCl4, FeCl3, and Li2O are weighed in a stoichiometric ratio of 2.21:0.75:0.25:0.04. In the ball milling process, the ball milling was performed intermittently for 10 hours at a ball-to-material mass ratio of 20:1 and a speed of 650 rpm. In the heat treatment step, under the protection of argon gas with a continuous flow of 50 sccm, the temperature was raised to 300℃ at a rate of 3℃ / min, held for 8 hours, and then cooled to room temperature with the furnace.

[0087] Example 2: In this embodiment, a=0.15, b=0.05, and the prepared molecular formula is Li2. 20 Zr0. 85 Fe0. 15 Cl5. 95 O0. 05 Halogen oxide electrolytes.

[0088] In the raw material preparation step, LiCl, ZrCl4, FeCl3, and Li2O were weighed in a stoichiometric ratio of 2.1:0.85:0.15:0.05. The remaining steps were the same as in Example 1.

[0089] Example 3: In this embodiment, a=0.1, b=0.02, and the prepared molecular formula is Li2. 12 Zr0.9Fe0.1Cl5. 98 O0. 02 Halogen oxide electrolytes.

[0090] In the raw material preparation step, LiCl, ZrCl4, FeCl3, and Li2O were weighed in a stoichiometric ratio of 2.08:0.9:0.1:0.02. The remaining steps were the same as in Example 1. Example 4: In this embodiment, a=0.3, b=0.08, and the prepared molecular formula is Li2. 38 Zr0.7Fe0.3Cl5. 92 O0. 08 Halogen oxide electrolytes.

[0091] In the raw material preparation step, LiCl, ZrCl4, FeCl3, and Li2O were weighed in a stoichiometric ratio of 2.22:0.7:0.3:0.08. The remaining steps were the same as in Example 1.

[0092] Comparative Example 1 is a halide electrolyte with the chemical formula Li2ZrCl6, that is, an LZC halide electrolyte that has not been doped with Fe or O.

[0093] Comparative Example 2 is a sample with the chemical formula Li2. 25 Zr0. 75 Fe0. 25 Cl6 halide electrolyte, i.e. LZC halide electrolyte with only Fe doping.

[0094] Comparative Example 3 is a product with the chemical formula Li2. 65 Zr0. 75 Fe0. 25 The Cl5.2O0.8 halide oxide electrolyte is a halide oxide electrolyte that has been doped with Fe and O, with doping amounts of a=0.25 and b=0.8.

[0095] Comparative Example 4 is a product with the chemical formula Li2. 65 Zr0. 95 Fe0. 05The Cl5.2O0.8 halide electrolyte is a halide electrolyte that has been doped with Fe and O, with doping amounts of a=0.05 and b=0.8. The difference between Comparative Example 4 and Comparative Example 3 is the different doping amounts of Fe.

[0096] The ionic conductivity of Examples 1 to 4 and Comparative Examples 1 to 4 described above was tested, and the results are shown in Table 1 below: Table 1: Ionic conductivity of electrolytes in each embodiment and comparative example

[0097] In one possible example, the general procedure for ionic conductivity testing is as follows: Take about 150mg of SFO-25 powder, put it into a polyether ether ketone (PEEK) mold with a diameter of 10mm, apply a pressure of 400MPa in a glove box using a hydraulic press, hold the pressure for 3 minutes, and press it into a dense disc (thickness of about 0.81mm). Electrochemical impedance spectroscopy (EIS) was performed using an electrochemical workstation with a frequency range of 7 MHz to 1 Hz and an amplitude of 10 mV. The bulk resistance (Ro) was obtained by fitting the data using ZView software. a According to the formula σ=L / (R) a *A) Calculate the ionic conductivity (σ), where L is the thickness of the electrolyte sheet and A is the area of ​​the stainless steel column.

[0098] Referring to the data in Table 1, based on Examples 1 to 4, when the parameter a characterizing the amount of Fe doping is in the range of 0 < a ≤ 0.4 (especially 0.1 ≤ a ≤ 0.3) and the parameter b characterizing the amount of O doping is in the range of 0 < b ≤ 0.1 (especially 0.02 < b ≤ 0.08), the prepared halide oxide electrolytes can maintain a high ionic conductivity of 1.38 mS / cm and exhibit excellent interfacial cycling stability. Compared with the undoped LZC halide electrolyte in Comparative Example 1 and the LZC halide electrolyte with only Fe doping in Comparative Example 2, the ionic conductivity of the halide oxide electrolyte of the present invention is significantly improved.

[0099] Based on Comparative Examples 3 and 4, when the ratio of O doping to Fe doping is unreasonable, the characteristic of Fe doping to improve ionic conductivity is affected by O doping. This may result in the ionic conductivity of the prepared halide electrolyte being slightly higher or even lower than that of the undoped LZC halide electrolyte. In other words, once the O doping amount is unreasonable, regardless of whether the Fe doping amount is high or low, it will lead to a decrease in ionic conductivity and cannot suppress the negative effect of O on LZC halide electrolyte.

[0100] The data in Table 1 verify the effectiveness and universality of Fe doping and O doping of the halide oxide electrolyte proposed in this invention. Compared with single Fe doping or O doping, the halide oxide electrolyte of this invention significantly improves ionic conductivity, which is beneficial to meeting the performance requirements of all-solid-state batteries for high ionic conductivity of solid electrolytes, improving the interface stability and cycle life with lithium metal anode, and having good matching with all-solid-state batteries with high voltage cathode, thus balancing high ionic conductivity and good stability.

[0101] The aforementioned Examples 1 to 4, as well as Comparative Examples 1 to 4, were assembled into batteries, and the cycle performance of the batteries was tested, resulting in the following Table 2: Table 2: Cyclic performance of electrolytes in each embodiment and comparative example

[0102] In one possible example, the general flow of a loop performance test is as follows: Take 100mg of Li 2+a+b Zr 1-a Fe a Cl 6-b O b The powder is pressed into a dense separator layer in a mold at a pressure of 200 MPa; a layer of high-purity lithium foil (usually 100-200 μm thick and slightly smaller in diameter than the electrolyte sheet) is uniformly attached to both sides of the pressed electrolyte disc, and then assembled in a mold at a pressure of 100 MPa. Using the LAND battery testing system, constant current cyclic charge and discharge tests were conducted in a constant temperature chamber at 25°C with a current density of 0.5 mA / cm2. The aforementioned charge and discharge cycles were continued until the battery voltage showed abnormal fluctuations (such as a sudden drop to near 0V, indicating a short circuit), the polarization voltage increased sharply (such as exceeding the set cutoff value, for example, 1V), or the predetermined time period was reached (such as more than 1000 hours). Record the absolute value of the voltage at a fixed capacity point in each cycle. Take half of the difference between the absolute values ​​of the voltages at the corresponding capacity points during the lithium deposition and lithium stripping processes in that cycle as the polarization voltage of that cycle (approximately representing the interface impedance).

[0103] Understandably, a lower polarization voltage indicates greater stability, which means a smaller interfacial impedance and smoother lithium-ion transport.

[0104] Referring to the data in Table 2, based on Examples 1 to 4, when the value range of parameter a, which characterizes the doping amount of Fe, is 0 < a ≤ 0.4 (especially 0.1 ≤ a ≤ 0.3), and the value range of parameter b, which characterizes the doping amount of O, is 0 < b ≤ 0.1 (especially 0.02 < b ≤ 0.08), the prepared halide oxide electrolytes can maintain a low polarization voltage, maintain a high ionic conductivity, and exhibit excellent interfacial cycle stability, resulting in batteries with good cycle performance.

[0105] Based on Comparative Examples 1 and 2, when oxygen is absent, even with Fe doping to improve ionic conductivity, the cycle stability of the resulting battery remains poor, and the interface stability is not optimized. Based on Comparative Examples 3 and 4, when the amount of O doping is unreasonable, both excessive and insufficient Fe doping will lead to a severe decrease in conductivity and interface deterioration, failing to suppress the negative effects of O on LZC halide electrolytes.

[0106] The data in Table 2 verify the effectiveness and universality of Fe doping and O doping of the halide oxide electrolyte proposed in this invention. Compared with single Fe doping or O doping, the halide oxide electrolyte of this invention significantly improves ionic conductivity, which is beneficial to meeting the high ionic conductivity performance requirements of solid-state batteries for solid electrolytes. It also improves the interfacial stability and cycle life with lithium metal anodes, and has good matching with high-voltage cathodes in all-solid-state batteries. It has good capacity retention and rate performance, and balances high ionic conductivity and good stability.

[0107] The present invention also proposes a battery comprising the aforementioned halide electrolyte, or comprising a halide electrolyte prepared by the aforementioned method for preparing halide electrolyte.

[0108] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A halide oxide electrolyte, characterized in that, The general chemical formula is Li 2+a+b Zr 1-a Fe a Cl 6-b O b , where the range of values ​​for a is 0 < a ≤ 0.4, and the range of values ​​for b is 0 < b ≤ 0.

1.

2. The halide oxide electrolyte according to claim 1, characterized in that, The value of a is in the range of 0.1≤a≤0.25, and / or the value of a is 0.1, 0.15, 0.25 or 0.

3.

3. The halide oxide electrolyte according to claim 1 or 2, characterized in that, The value of b is in the range of 0 < b ≤ 0.08, and / or the value of b is in the range of 0.02 ≤ b ≤ 0.05, and / or the value of b is 0.02, 0.04, 0.05 or 0.

08.

4. The halide oxide electrolyte according to claim 1, characterized in that, The ratio c of the doping amount of O to the doping amount of Fe is in the range of 0.08 ≤ c ≤ 0.

5.

5. The halide oxide electrolyte according to claim 1, characterized in that, Its chemical formula is Li₂. 29 Zr0. 75 Fe0. 25 Cl5. 96 O0. 04 Li2. 20 Zr0. 85 Fe0. 15 Cl5. 95 O0. 05 Li2. 12 Zr0.9Fe0.1Cl5. 98 O0. 02 And Li2. 38 Zr0.7Fe0.3Cl5. 92 O0. 08 At least one of them.

6. A method for preparing a halide oxide electrolyte, characterized in that, The preparation of the halide oxide electrolyte according to any one of claims 1 to 5 comprises the following steps: Raw material preparation: Under an inert atmosphere, lithium source, zirconium source, chlorine source, iron source and oxygen source were weighed according to stoichiometric ratio to obtain the first mixture; Ball milling treatment: The first mixture was ball milled under an inert atmosphere to obtain an electrolyte precursor; Heat treatment: The electrolyte precursor is heat-treated under an inert atmosphere to obtain the finished electrolyte product.

7. The method for preparing halide oxide electrolyte according to claim 6, characterized in that, The lithium source is LiCl, and / or the zirconium source is ZrCl4, and / or the iron source is FeCl3, and / or the oxygen source is Li2O.

8. The method for preparing halide oxide electrolyte according to claim 6, characterized in that, It also includes the following steps: Raw material pretreatment: Under vacuum or inert atmosphere protection, at least one of the lithium source, zirconium source, iron source and oxygen source is heated or dried.

9. The method for preparing halide oxide electrolyte according to claim 6 or 8, characterized in that, It also includes the following steps: Grinding and sieving: Under an inert atmosphere, the electrolyte product is ground and sieved to obtain the target electrolyte.

10. A battery, characterized in that, Includes the halide electrolyte according to any one of claims 1 to 5, or includes the halide electrolyte prepared by the method of preparing the halide electrolyte according to any one of claims 6 to 9.

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