Solid-state electrolyte, lithium-ion battery, and electronic apparatus

Abstract

To provide a solid-state electrolyte, a lithium-ion battery, and an electronic apparatus for improving issues in transport dynamics of ions affected by a larger particle diameter in the solid-state electrolyte.SOLUTION: In a lithium-ion battery, an electrolyte includes halides represented by formula (1), and at least part of the halides have a median particle diameter D50 of 50 nm to 3 μm. Li2+aZr1-aMaCl6-x-yBrxIy (1). In formula (1), 0<a≤0.6, 0≤x≤6, 0≤y≤6, x+y≤6, and M is at least one selected from V, Cr, Mn, Fe, Co, and Ni.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to the technical field of solid-state batteries, and in particular to solid electrolytes, ion batteries, and electronic devices. [Background technology]

[0002] In recent years, lithium-ion batteries have developed rapidly due to their advantages, such as high energy density, long cycle life, and environmental friendliness. Lithium-ion batteries are widely used in fields such as electric vehicles, aerospace, and portable devices. However, most currently available lithium-ion batteries use flammable organic liquid electrolytes, which pose significant safety hazards and limit their operating temperature. Furthermore, at low temperatures, organic solvents significantly reduce the ionic conductivity of the electrolyte. To improve the safety and energy density of lithium-ion batteries, non-flammable inorganic solid electrolytes have been used instead of liquid electrolytes. This is because inorganic solid electrolytes are better suited to high-voltage cathodes and can simplify the battery structure. Therefore, the development of all-solid-state batteries has become an important technological direction for next-generation batteries.

[0003] To advance the development of high-performance all-solid-state batteries, research is needed to develop solid electrolytes with high ionic conductivity and a wide electrochemical window. Furthermore, in all-solid-state batteries, the solid-solid interface between the electrode and solid electrolyte is crucial for electrochemical performance. Due to their permeability, organic liquid electrolytes can establish favorable electrode / electrolyte interfaces in lithium-ion batteries. However, in all-solid-state batteries, a solid electrolyte is typically added to the cathode as an ion conductor to enhance the ionic conductivity of the cathode. Lithium ion transport in the cathode is highly dependent on the ionic conductivity and particle size of the solid electrolyte, which determine the kinetics of lithium ion transport at the cathode and electrode-electrolyte interface. The ionic conductivity of the electrolyte layer is also affected by the particle size and grain boundary resistance of the solid electrolyte. Furthermore, the particle size and grain boundary fraction of the solid electrolyte in the cathode determine the interfacial contact area and stability with the active material, thereby affecting the interfacial resistance and lithium ion transport kinetics. Therefore, tuning the particle size of the solid electrolyte is crucial for the electrochemical performance of the cathode and electrolyte layer in all-solid-state batteries.

[0004] Currently, halide solid electrolytes are fabricated with larger particle sizes. Solid-state batteries using this type of electrolyte are more susceptible to stresses and strains within the battery during cycling, which can lead to electrolyte particle crushing and cracking, and a higher risk of lithium dendrites penetrating the electrolyte layer. Furthermore, larger electrolyte particles have a smaller specific surface area, which makes it more difficult for the cathode active material to contact the electrolyte in the cathode, significantly affecting the ion transport dynamics. This reduces the capacity, rate capability, and cycle performance of solid-state batteries.

[0005] Therefore, there is a demand for a solid electrolyte, a lithium ion battery, and an electronic device that can solve the above problems. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above-mentioned drawbacks of the related art, the present invention provides a solid electrolyte, a lithium-ion battery, and an electronic device for improving the problems in the ion transport dynamics affected by the larger particle size of the particles in the solid electrolyte.

Means for Solving the Problems

[0007] To achieve the above, a first aspect of the present invention provides a solid electrolyte containing a halide represented by the following formula (1), wherein the median particle size D50 of at least a part of the halide is 50 nm to 3 μm. Formula (1): Li 2+a Zr 1-a M a Cl 6-x-y Br x I y (1) In formula (1), 0 < a ≤ 0.6, 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, x + y ≤ 6, and M is selected from at least one of V, Cr, Mn, Fe, Co, and Ni.

[0008] In one embodiment of the present invention, in formula (1), M is Fe.

[0009] In one embodiment of the present invention, in formula (1), D50 is 100 nm to 1 μm.

[0010] In one embodiment of the present invention, D50 is 100 nm to 1 μm.

[0011] A second aspect of the present invention provides a lithium-ion battery, which includes a positive electrode, a negative electrode, and an electrolyte layer. The positive electrode includes a positive electrode active material and the above solid electrolyte.

[0012] In one embodiment of the present invention, the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium cobalt oxide, and lithium nickel cobalt aluminum oxide.

[0013] In one embodiment of the present invention, the positive electrode also contains a conductive agent, and the mass content of the conductive agent in the positive electrode is 0.05% to 10%.

[0014] In one embodiment of the present invention, the electrolyte layer comprises a halide.

[0015] In one embodiment of the present invention, the median particle size D50 of at least a part of the halide in the electrolyte layer is 50 nm to 3 μm.

[0016] A third aspect of the present invention further provides an electronic device, the electronic device including the lithium ion battery described above.

[0017] The solid electrolyte provided by the present invention is a halide. Furthermore, at least a part of the halide has a median particle size D50 of 50 nm to 3 μm. In other words, large particle size halide particles are nano-processed to form small particle size halide particles, thereby increasing the specific surface area of the halide particles. [Effects of the Invention]

[0018] The use of small particle size halide in the positive electrode increases contact between the positive electrode active material and the halide, contributing to the transport of lithium ions. This reduces interfacial resistance and improves battery efficiency and cycle performance. The use of small particle size halide in the electrolyte layer increases the compression density of the electrolyte layer, preventing electrolyte particle crushing and cracking, improving the safety performance of the battery. [Brief explanation of the drawings]

[0019] In order to more clearly illustrate the technical solutions provided in the embodiments of the present invention or related technologies, some accompanying drawings necessary for the description in the embodiments or related technologies are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0020] [Figure 1]1 is a flowchart of a method for manufacturing a solid electrolyte according to an embodiment of the present invention. [Figure 2] 1 is a schematic structural diagram of a lithium ion battery according to the present invention; [Figure 3] 1 is a schematic diagram of a lithium ion battery according to a first embodiment of the present invention. [Figure 4] 15 is a schematic structural diagram of a lithium ion battery according to Example 15 of the present invention. [Figure 5] 16 is a schematic structural diagram of a lithium ion battery according to Example 16 of the present invention. [Figure 6] 1 is a schematic structural diagram of a lithium ion battery according to Example 17 of the present invention. [Figure 7] 18 is a schematic structural diagram of a lithium ion battery according to Example 18 of the present invention. [Figure 8] 19 is a schematic structural diagram of a lithium ion battery according to Example 19 of the present invention. [Figure 9] FIG. 2 is a schematic structural diagram of a lithium ion battery according to Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The implementation of the present invention will be described below through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the disclosure of this specification. The present invention can also be implemented or applied through other different specific implementation methods. The details of this specification can be modified or changed based on different perspectives and applications without departing from the spirit of the present invention. Note that the following embodiments and features of each embodiment can be combined if not inconsistent.

[0022] 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 invention belongs. The terms used in the present specification are intended to describe particular embodiments only and are not intended to limit the present invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0023] Unless otherwise stated or contradictory, terms or phrases used in the specification have the following meanings:

[0024] As used herein, unless otherwise specified, references to "plurality," "multiple," "multiple," etc., mean that the quantity is greater than or equal to two. For example, "one or more" means one or more than one.

[0025] In this specification, the terms "preferable", "better", and "preferably" are used only to describe embodiments or examples that provide better effects, and do not limit the scope of the present invention. When a technical solution has multiple "preferable" descriptions, each "preferable" description is independent and does not contradict or limit each other, unless otherwise specified.

[0026] In this specification, the terms "further," "also," "particularly," and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of the invention.

[0027] In this specification, with respect to numerical ranges, unless otherwise specified, any distribution of values within the numerical range is considered continuous and includes both the two numerical endpoints (i.e., the minimum and maximum) of the numerical range and all values between the two numerical endpoints. When multiple numerical ranges are provided to describe a property or characteristic, these numerical ranges can be combined.

[0028] The present invention provides a solid electrolyte containing a halide represented by the following formula (1). Formula (1): Li 2+a Zr 1-a M a Cl 6-x-y Br x I y (1) In the formula, 0 < a ≤ 0.6, 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, and x + y ≤ 6, and M is selected from at least one of V, Cr, Mn, Fe, Co, and Ni.

[0029] In formula (1), M represents a doping element, which can be selected from at least one of Fe, Ni, Co, Mn, Al, Ga, and In. That is, M can be any one of the above-mentioned elements, or any combination of two or more. Preferably, M is Fe, and the equivalent substitution of Fe in the crystal lattice can improve the ionic conductivity of the electrolyte. a represents the doping amount of the M element, preferably 0.01 ≤ a ≤ 0.5. For example, a can be 0.01, 0.1, 0.3, or 0.5. x represents the doping amount of the Br element, and its value can be any value in the range of 0 to 6, such as x = 1, 3, 5, etc. y represents the doping amount of the I element, and its value can be any value in the range of 0 to 6, such as y = 2, 4, or 6, etc. In addition, 0 ≤ x + y ≤ 6. When x + y = 0, the halogen element in each halide is only the Cl element. When x + y = 6, the halogen element in each halide does not contain the Cl element.

[0030] ​​Furthermore, at least some of the halides provided by the present invention are halides having a median particle size D50 of 50 nm to 3 μm. Furthermore, D50 is 100 nm to 1 μm, for example, 100 nm, 500 nm, 800 nm, 1 μm, etc. Here, halides having a D50 of 50 nm to 3 μm are defined as first halides. Therefore, all of the halides provided by the present invention may be first halides, or some of the halides may be first halides and the remaining halides may be defined as second halides. The median particle size of the second halides is greater than 3 μm.

[0031] Halide electrolytes have the characteristics of high ionic conductivity and high voltage resistance, and are compatible with uncoated oxide cathode active materials. Therefore, the use of the halide provided by the present invention in batteries can not only effectively improve ion transport dynamics but also prevent the occurrence of space charge effects. Furthermore, since the halide does not contain rare earth metals, costs can be significantly reduced.

[0032] During research, the inventors discovered that large halide particles have a small specific surface area, making it difficult for them to contact the positive electrode active material in the positive electrode. This can affect ion transport dynamics and reduce the capacity, rate performance, and cycle performance of lithium-ion batteries. Therefore, in the present invention, a portion of the halide is nano-processed to produce small halide particles with a median particle size D50 of 50 nm to 3 μm. Halide particles within this particle size range can increase the specific surface area of the particles, improving contact between the electrolyte particles and the positive electrode active material, reducing interfacial resistance, and improving battery efficiency and cycle performance.

[0033] The above-mentioned halide can be obtained by referring to the conventional manufacturing method in the art. As an example, referring to Figure 1, the manufacturing process of the halide includes the following steps:

[0034] In S1, according to the stoichiometric ratio of the chemical formula of the halide, the corresponding amounts of compound raw materials containing Li, Zr, and M ions are added and mixed into a sealed container to obtain a halide precursor.

[0035] In S2, the halide precursor is heat treated, crushed and polished to obtain the halide.

[0036] In S3, at least a portion of the halide is subjected to a secondary treatment to obtain a first halide.

[0037] Specifically, the compounds containing Li, Zr, and M ions in step S1 include LiCl, ZrCl4, FeCl3, etc. Conventional methods capable of uniformly mixing raw materials, such as mechanical stirring, mechanical vibration, ball milling, roller milling, or a combination thereof, can be used for mixing. Preferably, ball milling is used for mixing. The ball milling rotation speed is 100 rpm to 1000 rpm, the mixing time is 0.5 to 3 hours, the diameter of the ball-milled zirconium beads is 5 mm to 20 mm, and the ball-to-material ratio is (20 to 50):1. During research, the applicant discovered that the above ball milling conditions enable more uniform mixing of the solid electrolyte raw materials and further improve the interfacial compatibility between the positive electrode active material and the solid electrolyte.

[0038] More preferably, in step S1, the rotation speed during ball mill mixing is 300 rpm, the ball mill time is 1 hour, the diameter of the ball mill zirconium beads is 10 mm, and the ratio of balls to material is 30:1.

[0039] The heat treatment in step S2 involves solid-phase sintering the precursor from step S1 in an inert gas atmosphere. Here, the temperature rise rate in the solid-phase sintering step is 2°C / min to 10°C / min, the sintering temperature is 200°C to 500°C, and the sintering time is 2 hours to 7 hours. The sintering time is calculated from the time it takes for the temperature to rise to the target sintering temperature.

[0040] More preferably, the heating rate in the solid-phase sintering step is 4°C / min to 5°C / min, the sintering temperature is 250°C to 350°C, and the sintering time is 3 hours to 5 hours. Through research into the sintering process, the present inventors have found that comprehensive control of the heating rate, sintering temperature, and sintering time as described above can strengthen the crystallinity of the halide and also make the intramolecular arrangement more regular, thereby further improving the ionic conductivity of the halide solid electrolyte.

[0041] After sintering and cooling, the sintered body is removed, crushed, and polished to obtain the halide. In the present invention, the cooling method after sintering is not particularly limited. For example, the halide solid electrolyte may be cooled by furnace cooling.

[0042] Since the halide electrolyte particles produced after sintering are large and do not contribute to contact with the positive electrode active material, step S3 is carried out in the present invention to perform secondary treatment on at least a portion of the halide produced in step S2 to obtain a halide (i.e., a first halide) with a small particle size that meets the requirements.

[0043] The secondary treatment method may be one or a combination of ultrasonic dispersion, mechanical vibration, mechanical stirring, ball milling, and roller milling. Preferably, mechanical stirring is used. That is, the halide prepared in step S2 is dispersed in a solvent, a dispersant is added, and the mixture is stirred until it is uniformly dispersed, and then the first halide is obtained after drying.

[0044] The solvent in step S3 can be selected from one or more of toluene, chlorobenzene, xylene, dimethyl carbonate, N-methylformamide, n-hexane, glyme, dibutyl ether, ethanol, 1,2-ethylenediamine, 1,2-ethanedithiol, acetonitrile, tetrahydrofuran, methanol, isopropyl ether, acetone, hexene, ethyl acetate, benzyl acetate, butyl butyrate, and diisobutyl ketone. Preferably, the solvent is xylene.

[0045] The dispersant in step S3 can be selected from one or more combinations of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetyltrimethylammonium sulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium octylsulfonate, polyethylene glycol octanol ether, polysorbate, polyoxyethylene stearyl alcohol ether, sodium coconut acid salt, sodium palmitate, sodium oleate, sodium dodecylsulfonate, or polysodium acrylate. Preferably, the dispersant is polyethylene glycol octanol ether.

[0046] The mass ratio of the halide to the solvent during the secondary treatment is 1:30 to 30:30, and preferably 1:20.

[0047] The mass percentage of the dispersant during the secondary treatment is 0.05% to 5%. % refers to the mass ratio of the dispersant in the mixed solution of the halide solid electrolyte and the solvent. Preferably, the mass percentage of the dispersant is 1%.

[0048] The drying method is vacuum filtration, vacuum drying, or air drying, or a combination of these methods. The drying method is preferably vacuum drying.

[0049] Referring to FIG. 2 , a second aspect of the present invention provides a lithium-ion battery. The lithium-ion battery includes a positive electrode 1, a negative electrode 3, and an electrolyte layer 2. The electrolyte layer 2 is disposed between the positive electrode 1 and the negative electrode 3 and is used to transport lithium ions between the positive electrode and the negative electrode. Here, the positive electrode 1 includes a positive electrode active material and the above-described solid electrolyte. Adding a small particle size halide to the positive electrode 1 increases the contact between the positive electrode active material and the halide electrolyte, contributing to the transport of lithium ions. Furthermore, the small particle size halide increases the specific surface area of the electrolyte particles, improving the contact between the electrolyte particles and the positive electrode, thereby reducing interfacial resistance and improving the battery's charge / discharge ratio and cycle performance.

[0050] In some embodiments, the positive electrode active material includes, but is not limited to, lithium nickel cobalt manganese oxide (NCM), lithium nickel oxide (LNO), lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), lithium cobalt oxide (LCO), and lithium nickel cobalt aluminum oxide (NCA). That is, the positive electrode active material may be any of the positive electrode materials described above, such as NCM, LNO, or LCO. The positive electrode active material may also be a combination of any two or more of the above, such as a combination of NCM and LMO or a combination of NCA and LCO. The specific type of positive electrode active material may be selected based on actual needs.

[0051] The positive electrode 1 includes a positive electrode active material and a solid electrolyte. The median particle size D50 of at least a portion of the halide in the solid electrolyte is 50 nm to 3 μm. Therefore, the positive electrode 1 exists in two states: a state in which the positive electrode 1 includes a positive electrode active material and a first halide, and a state in which the positive electrode 1 includes a positive electrode active material, the first halide, and a second halide. The ratio of the positive electrode active material to the halide (including the first halide and the second halide) can be set with reference to the ratio of the positive electrode active material to the solid electrolyte in a conventional composite positive electrode. For example, the mass ratio of the positive electrode active material to the halide is (50 to 75):(20 to 50).

[0052] In some embodiments, the positive electrode 1 further includes a conductive agent, which includes at least one of graphite, graphene, conductive carbon black (Super P), conductive carbon fiber (VGCF), and carbon nanotubes. The conductive agent may be any one or a combination of two or more of the above. Furthermore, the conductive agent includes one or both of conductive carbon black and conductive carbon fiber. Preferably, the conductive agent is a composition in which conductive carbon black (Super P) and conductive carbon fiber are mixed in a mass ratio of 1:1.

[0053] The mass percentage of the conductive agent in the positive electrode 1 is 0.05% to 10%, and as an example, the mass percentage of the conductive agent in the positive electrode may be 0.05%, 1%, 5%, 8%, or 10%.

[0054] Referring to FIG. 2, in some embodiments, electrolyte layer 1 contains a halide in a solid electrolyte. The halide may be a halide (second halide) that has not undergone any secondary treatment, may be a first halide having a median particle size of 50 nm to 3 μm, or may be a combination of a first halide and a second halide. Preferably, electrolyte layer 2 at least partially contains a first halide. Because the particle size of the first halide is small, adding a small-particle-size halide to electrolyte layer 2 increases the compaction density of electrolyte layer 2, thereby preventing electrolyte particle crushing and cracking and improving battery safety performance. Note that when electrolyte layer 2 contains both a first halide and a second halide, the mass ratio of the second halide to the first halide is 0:10 to 9:1, such as 1:1, 3:1, 6:1, or 9:1. When the mass ratio of the two is 0:10, it means that the electrolyte layer 2 does not contain the second halide and is composed entirely of the first halide.

[0055] In the present invention, the negative electrode of a lithium-ion battery generally refers to a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector in this technical field. Here, the negative electrode active material layer includes a negative electrode active material. The negative electrode active material may be a graphite material, a silicon material, metallic lithium, metallic indium, a lithium-indium alloy, or a composite material of a graphite material and a silicon material. Here, graphite materials include natural graphite (lump graphite, flake graphite, amorphous graphite) and artificial graphite (single crystal graphite, polycrystalline graphite, pyrolytic graphite, graphite fiber, etc.). Silicon materials include, but are not limited to, elemental silicon and silicon oxide compounds.

[0056] The lithium ion battery can be fabricated into an all-solid-state pouch battery by assembling the positive electrode, electrolyte layer, and negative electrode sheets prepared above through lamination, packaging, hot pressing, and cold pressing processes using methods commonly used in this technical field.

[0057] The present invention further provides an electronic device including the lithium ion battery. The lithium ion battery can be used in the electronic device in the form of a single cell, a battery module, or a battery pack.

[0058] The electronic devices provided by the present invention include, but are not limited to, mobile phones, tablets, laptops, electric toys, battery cars, new energy vehicles, ships, aircraft, etc. Here, the electric toys include, but are not limited to, stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, electric plane toys, etc. The aircraft include, but are not limited to, airplanes, rockets, space shuttles, spaceships, etc. The new energy vehicles may be pure electric vehicles, hybrid vehicles, extended range vehicles, etc.

[0059] The technical solutions of the present invention will be described in detail below through several specific examples and comparative examples. Those skilled in the art should understand that the examples are only intended to help understand the present invention and should not be considered as specific limitations of the present invention. Unless otherwise stated, all raw materials and reagents used in the following examples are commercially available or can be prepared by conventional methods in the art, and all equipment used in the examples is commercially available.

[0060] Example 1

[0061] This example provides a solid electrolyte, which is a halide Li2ZrCl5Br 0.5 I 0.5 wherein at least a portion of the halide has a first median particle size D50 of 100 nm; The remaining portion is secondary halides with a median particle size of 8 μm.

[0062] The process for preparing the halide is provided as follows:

[0063] In a dry atmosphere, the raw materials LiCl and ZrCl4 were added into a high-energy ball milling tank according to the stoichiometric ratio, and the precursor was obtained after ball milling. The precursor powder was heat-treated and ground into powder to obtain Li2ZrCl5Br with a particle size of 8 μm. 0.5 I 0.5 The halide was obtained by adding the obtained halide to a certain amount of xylene solution in a mass ratio of halide to solvent = 1:20, adding 1% polyethylene glycol octanol ether, mechanically stirring until homogeneous, and vacuum drying to obtain Li2ZrCl5Br with a particle size of 100 nm. 0.5 I 0.5 The halide (first halide) was obtained.

[0064] Positive electrode: 70% by mass of Li2ZrCl5Br 0.5 I 0.5 , 1% conductive agent (a conductive agent made by mixing Super P and VGCF in a mass ratio of 1:1), Li2ZrCl5Br with a particle size of 100 nm 0.5 I 0.5 29% of small particle halide was mixed into a homogeneous positive electrode.

[0065] Electrolyte layer: Li2ZrCl5Br with particle size of 8 μm 0.5 I 0.5 Halides.

[0066] Anode: Lithium indium alloy is the anode.

[0067] Lithium-ion battery assembly: The positive electrode, electrolyte layer, and negative electrode prepared above are assembled into an all-solid-state pouch battery through processes such as lamination, packaging, hot pressing, and cold pressing. A simplified battery structure is shown in Figure 3 (the negative electrode is omitted).

[0068] Fig. 3 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this example. From Fig. 3, it can be seen that the positive electrode 1 contains a uniformly mixed positive electrode active material and a first halide with a small particle size, and the electrolyte layer 2 contains only a second halide with a large particle size.

[0069] Example 2

[0070] The difference between this example and Example 1 is that the chemical formula of the halide is Li 2.1 Zr 0.9 Fe 0.1 Cl5Br 0.5 I 0.5 That is to be.

[0071] Example 3

[0072] The difference between this example and Example 1 is that the chemical formula of the halide is Li 2.2 Zr 0.8 Fe 0.2 Cl5Br 0.5 I 0.5 That is to be.

[0073] Example 4

[0074] The difference between this example and Example 1 is that the chemical formula of the halide is Li 2.3 Zr 0.7 Fe 0.3 Cl5Br 0.5 I 0.5 That is to be.

[0075] Example 5

[0076] The difference between this example and Example 1 is that the chemical formula of the halide is Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 That is to be.

[0077] Example 6

[0078] The difference between this example and Example 1 is that the chemical formula of the halide is Li2.4 Zr 0.6 Fe 0.4 Cl5Br 0.5 I 0.5 That is to be.

[0079] Example 7

[0080] The difference between this example and Example 1 is that the chemical formula of the halide is Li 2.5 Zr 0.5 Fe 0.5 Cl5Br 0.5 I 0.5 That is to be.

[0081] Example 8

[0082] The difference between this example and Example 1 is that the chemical formula of the halide is Li 2.6 Zr 0.4 Fe 0.6 Cl5Br 0.5 I 0.5 That is to be.

[0083] Example 9

[0084] The difference between this example and Example 5 is that the particle size of the first halide is 50 nm.

[0085] Example 10

[0086] The difference between this example and Example 5 is that the particle size of the first halide is 300 nm.

[0087] Example 11

[0088] The difference between this example and Example 5 is that the particle size of the first halide is 500 nm.

[0089] Example 12

[0090] The difference between this example and Example 5 is that the particle size of the first halide is 750 nm.

[0091] Example 13

[0092] The difference between this example and Example 5 is that the particle size of the first halide is 1 μm.

[0093] Example 14

[0094] The difference between this example and Example 5 is that the particle size of the first halide is 3 μm.

[0095] Example 15

[0096] The difference between this example and Example 5 is that 29% of the halide in the positive electrode 1 is Li with a mass ratio of 1:1 and a particle size of 8 μm. 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Halide electrolyte and 100nm particle size Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The remaining steps were the same as in Example 5, and the simplified battery structure is shown in Figure 4 (the negative electrode is omitted).

[0097] Fig. 4 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this example. From Fig. 4, it can be seen that the positive electrode 1 contains a uniformly mixed positive electrode active material, a small particle size first halide, and a large particle size second halide, and the electrolyte layer 2 contains only the large particle size second halide.

[0098] Example 16

[0099] The difference between this example and Example 5 is that the electrolyte layer 2 is made of Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Halide electrolyte and 100nm particle size Li 2.35 Zr 0.65 Fe0.35 Cl5Br 0.5 I 0.5 The remaining steps were the same as in Example 5, and the simplified battery structure is shown in Figure 5 (the negative electrode is omitted).

[0100] Fig. 5 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this example. From Fig. 5, it can be seen that the positive electrode 1 contains a uniformly mixed positive electrode active material and a first halide with a small particle size, and the electrolyte layer 2 contains a first halide with a small particle size and a second halide with a large particle size.

[0101] Example 17

[0102] The difference between this example and Example 5 is that the electrolyte layer 2 is made of Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The remaining steps are the same as in Example 5, and the simplified battery structure is shown in Figure 6 (the negative electrode is omitted).

[0103] Fig. 6 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this example. From Fig. 6, it can be seen that the positive electrode 1 contains a uniformly mixed positive electrode active material and a small particle size first halide, and the entire electrolyte layer 2 is formed from a small particle size first halide.

[0104] Example 18

[0105] The difference between this example and Example 15 is that the electrolyte layer 2 is made of Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Halide and 100nm particle size Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5The remaining steps were the same as in Example 15, and the simplified battery structure is shown in Figure 7 (the negative electrode is omitted).

[0106] 7 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this example. From FIG. 7, it can be seen that the positive electrode 1 contains a uniformly mixed positive electrode active material, a first halide with a small particle size, and a second halide with a large particle size, and the electrolyte layer 2 contains a uniform dispersion of the first halide with a small particle size and the second halide with a large particle size.

[0107] Example 19

[0108] The difference between this example and Example 15 is that the electrolyte layer 2 is made of Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The remaining steps were the same as in Example 15, and a simplified battery structure is shown in Figure 8 (the negative electrode is omitted).

[0109] Fig. 8 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this example. From Fig. 8, it can be seen that the positive electrode 1 contains a uniformly mixed positive electrode active material, a first halide with a small particle size, and a second halide with a large particle size, and the electrolyte layer 2 contains only the first halide with a small particle size.

[0110] Comparative Example 1

[0111] In a dry atmosphere, the raw materials were added to a high-energy ball mill tank according to stoichiometric amounts. After ball milling, the precursor powder was heat-treated and ground into powder to obtain Li SiO 2 with a particle size of 8 μm. 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 A halide electrolyte was obtained.

[0112] 70% by mass LiNi 0.8 Co 0.1 Mn 0.1O2, 1% conductive agent (a conductive agent made by mixing Super P and VGCF in a mass ratio of 1:1), Li with a particle size of 8 μm 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The electrolyte layer is a mixture of 29% halide electrolyte and a uniform positive electrode. 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 An all-solid-state battery was assembled using a halide electrolyte and a lithium-indium alloy anode. A simplified battery structure is shown in Figure 9 (the anode is omitted).

[0113] Fig. 9 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this comparative example. From Fig. 9, it can be seen that the uniformly mixed positive electrode 1 contains the positive electrode active material and the large particle size second halide, and the electrolyte layer 2 contains only the large particle size second halide.

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 1 is that the chemical formula of the halide is Li 2.8 Zr 0.2 Fe 0.8 Cl5Br 0.5 I 0.5 That is to be.

[0116] Comparative Example 3

[0117] The difference between this comparative example and Example 1 is that the chemical formula of the halide is Li 2.95 Zr 0.05 Fe 0.95 Cl5Br 0.5 I 0.5 That is to be.

[0118] The ionic conductivity of the first halides prepared in the examples and comparative examples was tested, and the test results are shown in Table 1. The test method was as follows.

[0119] Ionic conductivity: The halide powder was pressed into a 10 mm diameter sheet at 360 MPa. Stainless steel sheets were then used as ion-blocking electrodes on both sides of the sheet to fabricate an ion-blocking battery. An electrochemical workstation with a frequency range of 106-1 Hz and an amplitude of 5 mV was used for EIS testing. The equation σ = L / (R*A) was used to calculate the ionic conductivity of the electrolyte membrane. In this equation, L is the thickness of the electrolyte membrane, A is the effective area of the electrolyte membrane, and R is the bulk resistance of the electrolyte membrane. The resistance value was calculated at the intersection of the EIS curve and the real axis.

[0120] Table 1: Ion conductivity and particle size of the first halide electrolyte in each example and comparative example [Table 1]

[0121] As can be seen from Table 1, when the doping amount a of Fe ions in the halides of Examples 1 to 8 is in the range of 0 to 0.6, the ionic conductivity of the halides is 4×10 -4 Scm -1 As the doping amount of Fe ions increases, the ionic conductivity increases gradually at first, then decreases after reaching an optimum value. When the doping amount of Fe ions a is greater than 0.6 (Comparative Examples 2 and 3), the ionic conductivity of the halide decreases significantly, becoming much lower than that of the halide of the present invention.

[0122] Comparing Example 5 and Examples 9 to 14 with Comparative Example 1, it is found that the ionic conductivity of the same halide increases as the particle size increases.

[0123] A cycle performance test was carried out on the lithium ion batteries of the above Examples and Comparative Examples. The test results are shown in Table 2. The test method was as follows.

[0124] The battery fabricated above was repeatedly charged and discharged at 25°C, and the number of cycles at room temperature until the SOH reached 80% was measured and recorded. The operating voltage range was 2.8V to 4.35V, and the charge / discharge rate was 1C / 1C. [Table 2]

[0125] As can be seen from Table 2, in Examples 1 to 8, as the doping amount of Fe ions in the halide increases, the cycle performance of the lithium ion battery initially gradually improves and then gradually deteriorates. When the doping amount of Fe ions a exceeds 0.6 (Comparative Examples 2 and 3), the cycle performance of the battery significantly deteriorates and even short circuits occur.

[0126] Comparing Examples 5 and 9 to 14 with Comparative Example 1, it is clear that even with the same halide, the cycle performance of the battery gradually decreases as the particle size increases.

[0127] Comparing Example 5 and Examples 15 to 19 with Comparative Example 1, it is clear that the cycle performance of a lithium ion battery can be significantly improved by adding at least a portion of the small particle size halide to the positive electrode and / or electrolyte layer. [Industrial Applicability]

[0128] In the present invention, Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I yThe halide is subjected to a secondary treatment to reduce its particle size to nanometer size, significantly reducing the particle size of the halide particles and increasing their specific surface area. By completely or partially replacing the original large-particle halide electrolyte with a small-particle halide, contact between the electrolyte and the positive electrode active material can be increased. This improves the lithium ion transport efficiency and prevents performance degradation due to localized poor contact. Furthermore, electrolyte pulverization and cracking during battery cycling can be avoided, improving the battery's cycle performance and energy density. Therefore, the present invention effectively solves several practical problems in the prior art and demonstrates great utility and practical significance.

[0129] The above-described embodiments are illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Those skilled in the art may modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention are still intended to be included in the scope of the claims of the present invention. [Explanation of symbols]

[0130] S1~S3: Process 1: Positive electrode 2: Electrolyte layer 3: Negative electrode

Claims

1. A solid electrolyte comprising a halide represented by the following formula (1), wherein the median particle size D50 of at least a part of the halide is 50 nm to 3 μm. Li ２＋ａ Zr １－ａ M ａ Cl ６－ｘ－ｙ Br ｘ I ｙ (1) In the formula, 0 < a ≤ 0.6, 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, x + y ≤ 6, and M is selected from at least one of V, Cr, Mn, Fe, Co, and Ni.

2. In the formula (1), M is Fe. The solid electrolyte according to Claim 1.

3. In the formula (1), 0.01 ≤ a ≤ 0.

5. The solid electrolyte according to Claim 2.

4. The D50 is 100 nm to 1 μm. The solid electrolyte according to any one of Claims 1 to 3.

5. A lithium-ion battery comprising a positive electrode, a negative electrode, and an electrolyte layer. The positive electrode includes a positive electrode active material and the solid electrolyte according to any one of Claims 1 to 3.

6. The electrolyte layer contains the halide. The solid electrolyte according to Claim 5.

7. The median particle size D50 of at least a part of the halide in the electrolyte layer is 50 nm to 3 μm. The solid electrolyte according to Claim 6.

8. A battery device comprising the lithium-ion battery according to Claim 5.

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