Solid electrolyte, lithium ion battery, and electronic device

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 more particularly to solid electrolytes, ion batteries, and electronic devices.

Background Art

[0002] In recent years, lithium-ion batteries have been rapidly developing due to 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 of the currently available lithium-ion batteries use flammable organic liquid electrolytes, which cause significant safety problems and limitations in 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 are used instead of liquid electrolytes. This is because inorganic solid electrolytes can better adapt to high-voltage cathodes and can simplify the battery structure. Therefore, the development of all-solid-state batteries has become one of the important technical directions for next-generation batteries.

[0003] To promote the development of high-performance all-solid-state batteries, it is necessary to study 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 the solid electrolyte is important for electrochemical performance. Organic liquid electrolytes can construct a good electrode / electrolyte interface in lithium-ion batteries due to their permeability. However, in all-solid-state batteries, usually, in order to increase the ionic conductivity of the positive electrode, it is necessary to add a solid electrolyte as an ion conductor to the positive electrode. The transport of lithium ions in the positive electrode greatly depends on the ionic conductivity and particle size of the solid electrolyte, and these determine the transport dynamics of lithium ions at the positive electrode and the electrode-electrolyte interface. Also, the ionic conductivity of the electrolyte layer is affected by the particle size and grain boundary resistance of the solid electrolyte. Furthermore, the particle size and grain boundary part of the solid electrolyte in the positive electrode determine the interface contact area and stability against the active material, thereby affecting the interface resistance and the transport dynamics of lithium ions. Therefore, the adjustment of the particle size of the solid electrolyte is important for the electrochemical performance of the positive electrode layer and the electrolyte layer of all-solid-state batteries.

[0004] Currently, the fabricated halide solid electrolytes have larger particle sizes. All-solid-state batteries using this type of electrolyte are more susceptible to the influence of stress and strain inside the battery during cycling, and there is a high risk of electrolyte particle pulverization, cracking, or lithium dendrites penetrating the electrolyte layer. Furthermore, the larger the electrolyte particles, the smaller the specific surface area, making it difficult for the positive electrode active material to contact the electrolyte inside the positive electrode, which significantly affects the transport dynamics of ions. As a result, the capacity, rate performance, and cycle performance of all-solid-state batteries deteriorate.

[0005] Therefore, there is a need for solid electrolytes, lithium-ion batteries, and electronic devices to solve the above problems.

Summary of the Invention

Problems 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 problems in ion transport dynamics affected by larger particle sizes of 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 contains 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] The third aspect of the present invention further provides an electronic device, and the electronic device includes the above lithium-ion battery.

[0017] The solid electrolyte provided by the present invention is a halide. Furthermore, the median particle size D50 of at least a part of the halide is 50 nm to 3 μm. That is, the large-particle-size halide is nano-processed into a small-particle-size halide to increase the specific surface area of the halide particles.

Advantages of the Invention

[0018] By using a small-particle-size halide in the positive electrode, the contact between the positive electrode active material and the halide increases, contributing to the transport of lithium ions. Thereby, the interfacial resistance is reduced, and the battery rate and cycle performance are improved. By using a small-particle-size halide in the electrolyte layer, the compression density of the electrolyte layer increases, thus preventing the pulverization and cracking of the electrolyte particles and improving the safety performance of the battery.

Brief Description of the Drawings

[0019] To more clearly show the technical solutions provided in the embodiments of the present invention or related technologies, some attached 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

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0021] The implementation of the present invention will be described below with reference to 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 also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and the features of each embodiment can be combined if they do not conflict.

[0022] Unless otherwise defined, all technical and scientific terms used in this specification 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 specification of the present invention are for the purpose of describing 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 specified or inconsistent, the terms or phrases used in the specification have the following meanings.

[0024] As used herein, references to "a plurality of", "plural", "numerous", etc. mean, unless otherwise specified, that the quantity is greater than or equal to 2. For example, "one or more" means one or two or more.

[0025] As used herein, "preferred", "better", and "favorable" are used only to describe embodiments or examples that provide better effects. Note that they do not limit the scope of the present invention. When there are multiple descriptions of "preferred" in a technical solution, unless otherwise specified, each description of "preferred" is independent and there is no contradiction or mutual restriction.

[0026] As used herein, "further", "also", "especially", etc. are used for the purpose of explanation and indicate differences in content, but should not be understood as limiting the scope of the present invention.

[0027] As used herein, with respect to numerical ranges, unless otherwise specified, the distribution of any value within the numerical range is considered continuous, and the two numerical endpoints of the numerical range (i.e., the minimum value and the maximum value), and all values between the two numerical ends are included. When multiple numerical ranges are provided to describe a property or characteristic, these numerical ranges can also 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、x+y≦6であり、Mは、V、Cr、Mn、Fe、Co、及びNiの少なくとも1つから選択される。

[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 elements, or a combination of any two or more of them. Preferably, M is Fe, and Fe in the crystal lattice is 0.01 to 0.01. 3+ The equivalent substitution of M can improve the ionic conductivity of the electrolyte. a represents the doping amount of M element, and is preferably 0.01≦a≦0.5, and for example, a may be 0.01, 0.1, 0.3, or 0.5. x represents the doping amount of Br element, and its value is any value in the range of 0 to 6, such as x=1, 3, or 5. y represents the doping amount of I element, and its value is any value in the range of 0 to 6, such as y=2, 4, or 6. Note that 0≦x+y≦6, and when x+y=0, the halogen element in each halide is only Cl element, and when x+y=6, the halogen element in each halide does not include Cl element.

[0030] Furthermore, at least a part of the halide provided by the present invention is a halide having a median particle size D50 of 50 nm to 3 μm. Further, D50 is 100 nm to 1 μm, such as 100 nm, 500 nm, 800 nm, 1 μm, etc. Here, the halide with D50 of 50 nm to 3 μm is defined as the first halide. Therefore, all of the halides provided by the present invention may be the first halide, or a part of the halide may be the first halide, and the remaining halide may be defined as the second halide. The median particle size of the second halide is larger than 3 μm.

[0031] The halide as an electrolyte is characterized by high ionic conductivity and high voltage resistance, and has good compatibility with the uncoated oxide cathode active material. Therefore, by using the halide provided by the present invention in a battery, not only can the ion transport dynamics be effectively improved, but also the occurrence of the space charge effect can be prevented. Furthermore, since the halide does not contain rare earth metals, the cost can be significantly reduced.

[0032] During the research, the inventors found that large particles of the halide have a small specific surface area, so it is difficult to contact the cathode active material in the cathode, which may affect the ion transport dynamics and reduce the capacity, rate performance, and cycle performance of the lithium-ion battery. Therefore, in the present invention, a part of the halide is nano-processed to obtain small particle halide with a median particle size D50 of 50 nm to 3 μm. The halide within this particle size range can increase the specific surface area of the particles, improve the contact between the electrolyte particles and the cathode active material, reduce the interfacial resistance, and improve the battery rate and cycle performance.

[0033] The above-mentioned halide can be obtained by referring to the conventional manufacturing methods in the technical field. As an example, referring to FIG. 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 the compound raw materials containing Li, Zr, and M ions are added to a sealed container and mixed to obtain a halide precursor.

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

[0036] In S3, at least a part of the halide is secondarily treated to obtain a first halide.

[0037] Specifically, the compounds containing Li, Zr, and M ions in step S1 include LiCl, ZrCl4, FeCl3, etc. The mixing method can use conventional methods in this technical field that can uniformly mix the raw materials, such as one or a combination of mechanical stirring, mechanical vibration, ball milling, roller milling, etc. Preferably, ball milling is used for mixing. The rotation speed during ball milling is 100 rpm to 1000 rpm, the mixing time is 0.5 hour to 3 hours, the diameter of the zirconium beads treated by ball milling is 5 mm to 20 mm, and the ratio of balls to materials is (20 - 50):1. During the research process, the applicant found that under the above ball milling conditions, the raw materials of the solid electrolyte can be mixed more uniformly, and the interfacial compatibility between the cathode active material and the solid electrolyte is further improved.

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

[0039] The heat treatment in step S2 is to perform solid-phase sintering on the precursor of step S1 in an inert gas atmosphere. Here, the heating rate in the solid-phase sintering process 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. Note that the sintering time is calculated from the time after heating to the target sintering temperature.

[0040] More preferably, the heating rate in the solid-phase sintering process 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. In the present invention, through the study of the sintering process, by comprehensively controlling the above-mentioned heating rate, sintering temperature, and sintering time, the crystallinity of the halide can be enhanced, and since the arrangement within the molecule becomes more regular, it has been found that the ionic conductivity of the halide solid electrolyte is further improved.

[0041] After sintering and cooling, the sintered body is taken out, pulverized, and polished to obtain a 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] The halide electrolyte particles produced after sintering are large and do not contribute to the contact with the positive electrode active material. Therefore, in the present invention, step S3 is executed, and at least a part of the halide produced in step S2 is secondary-treated to obtain a halide with a small particle size (i.e., the first halide) that meets the requirements.

[0043] The above 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 produced in step S2 is dispersed in a solvent, a dispersant is added, and stirring is performed until it is uniformly dispersed, and the first halide is obtained after drying.

[0044] The solvent in step S3 can be selected from one or a combination 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, or diisobutyl ketone. Preferably, the solvent is xylene.

[0045] The dispersant in step S3 can be selected from one or a combination of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetyltrimethylammonium sulfonate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium octyl sulfonate, polyethylene glycol octanol ether, polysorbate, polyoxyethylene stearyl alcohol ether, sodium ricinoleate, sodium palmitate, sodium oleate, sodium dodecyl sulfonate, or sodium polyacrylate. 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. Preferably, the mass ratio of the halide to the solvent is 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 any one of vacuum filtration, vacuum drying, air drying, or a combination of these methods. Preferably, the drying method is vacuum drying.

[0049] Referring to Figure 2, the 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-mentioned solid electrolyte. When a small particle size halide is added to the positive electrode 1, the contact between the positive electrode active material and the halide electrolyte increases, contributing to the transport of lithium ions. Furthermore, the small particle size halide can increase the specific surface area of the electrolyte particles and improve the contact between the electrolyte particles and the positive electrode, thereby reducing the interfacial resistance and improving the battery rate 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 above-mentioned positive electrode materials, for example, NCM, LNO, LCO, etc. The positive electrode active material may 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 the positive electrode active material may be selected according to 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 part of the halides in the solid electrolyte is 50 nm to 3 μm. Therefore, in the positive electrode 1, there are a state in which the positive electrode 1 includes the positive electrode active material and the first halide, and a state in which the positive electrode 1 includes the positive electrode active material, the first halide, and the second halide. Here, the ratio of the positive electrode active material to the halides (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 the conventional composite positive electrode. For example, the mass ratio of the positive electrode active material to the halides is (50 to 75):(20 to 50).

[0052] In some embodiments, the positive electrode 1 further includes a conductive agent, and the conductive agent includes at least one of graphite, graphene, conductive carbon black (Super P), conductive carbon fiber (VGCF), and carbon nanotube. The conductive agent may be any one or a combination of two or more of the above. Further, 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 at a mass ratio of 1:1.

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

[0054] Referring to FIG. 2, in some embodiments, the electrolyte layer 1 contains a halide in the solid electrolyte. The halide may all be halides that have not been subjected to secondary treatment (second halides), may all be first halides with a median particle size of 50 nm to 3 μm, or may be a combination of the first halide and the second halide. Preferably, the electrolyte layer 2 contains at least partially the first halide. Since the particle size of the first halide is small, by adding the small-particle-size halide to the electrolyte layer 2, the compression density of the electrolyte layer 2 increases, thus preventing the pulverization and cracking of the electrolyte particles and improving the safety performance of the battery. When the electrolyte layer 2 contains both the first halide and the second halide, the mass ratio of the second halide to the first halide is 0:10 to 9:1, for example, 1:1, 3:1, 6:1, or 9:1, etc. 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 entirely composed of the first halide.

[0055] In the present invention, the negative electrode of the lithium-ion battery generally means, in the technical field, a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. Here, the negative electrode active material layer contains a negative electrode active material. The type of 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, etc. Here, examples of the graphite material include natural graphite (lump graphite, flake graphite, earthy graphite), artificial graphite (single crystal graphite, polycrystalline graphite, pyrolytic graphite, graphite fiber, etc.). Examples of the silicon material include, but are not limited to, elemental silicon, silicon oxide compounds, etc.

[0056] The lithium-ion battery can assemble the positive electrode, electrolyte layer, and negative electrode sheet fabricated above through processes such as lamination, packaging, hot pressing, and cold pressing by a method generally used in the technical field to assemble a all-solid-state pouch battery.

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

[0058] The electronic device provided by the present invention includes, but is not limited to, mobile phones, tablets, notebook computers, electric toys, battery cars, new energy vehicles, ships, airplanes, etc. Here, the electric toys include, but are not limited to, stationary or mobile electric toys, such as game machines, electric vehicle toys, electric boat toys, electric airplane toys, etc. The airplanes include, but are not limited to, airplanes, rockets, space shuttles, spacecraft, etc. The new energy vehicles may be pure electric vehicles, hybrid vehicles, range-extended vehicles, etc.

[0059] Hereinafter, the technical solutions of the present invention will be described in detail through several specific examples and comparative examples. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention. Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available or can be prepared by the ordinary methods in the technical field, and all equipment used in the examples is commercially available.

[0060] Example 1

[0061] This example provides a solid electrolyte, and the solid electrolyte contains the halide Li2ZrCl5Br 0.5 I 0.5 Here, at least a part of the halide is a halide with a first median particle size D50 of 100 nm, and the remaining part is a secondary halide with a median particle size of 8 μm.

[0062] The preparation process of the halide is provided as follows.

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

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

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

[0066] Negative electrode: A lithium indium alloy is the negative electrode.

[0067] Lithium-ion battery assembly: The positive electrode, electrolyte layer, and negative electrode prepared above were assembled into a all-solid 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] Figure 3 clearly shows the material compositions of the positive electrode 1 and the electrolyte layer 2 in this embodiment. From Figure 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 is that.

[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 is that.

[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 is that.

[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 is that.

[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 is this.

[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 is this.

[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 is this.

[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 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 a mixed electrolyte of a halide electrolyte and a small particle size halide electrolyte with a particle size of 100 nm. The remaining steps are the same as those in Example 5, and the simplified battery structure is shown in Fig. 4 (the negative electrode is omitted). 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Fig. 4 clearly shows the material composition 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 positive electrode active material uniformly mixed, 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 second halide with a large particle size.

[0097] Fig. 4 clearly shows the material composition 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 positive electrode active material uniformly mixed, 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 second halide with a large particle size.

[0098] Example 16

[0099] The difference between this example and Example 5 is that the electrolyte layer 2 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 a halide electrolyte and a small particle size halide electrolyte with a particle size of 100 nm. 2.35 Zr 0.65 Fe0.35 Cl5Br 0.5 I 0.5 It is a mixed electrolyte with a small particle size halide electrolyte. The remaining steps are the same as in Example 5, and the simplified battery structure is shown in Fig. 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 small particle size first halide, and the electrolyte layer 2 contains a small particle size first halide 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 a small particle size halide electrolyte 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 Fig. 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 by 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 a halide with a mass ratio of 1:1 and a particle size of 8 μm of Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 and a halide of Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5It is a composition with a small particle size halide. The remaining steps are the same as in Example 15, and the simplified battery structure is shown in Fig. 7 (the negative electrode is omitted).

[0106] Fig. 7 clearly shows the material composition 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 small particle size first halide, and a large particle size second halide, and the electrolyte layer 2 is one in which the small particle size first halide and the large particle size second halide are uniformly dispersed.

[0107] Example 19

[0108] The difference between this example and Example 15 is that the electrolyte layer 2 is a small particle size halide. The remaining steps are the same as in Example 15, and the simplified battery structure is shown in Fig. 8 (the negative electrode is omitted). 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 It is a small particle size halide. The remaining steps are the same as in Example 15, and the simplified battery structure is shown in Fig. 8 (the negative electrode is omitted).

[0109] Fig. 8 clearly shows the material composition 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 small particle size first halide, and a large particle size second halide, and the electrolyte layer 2 contains only the small particle size first halide.

[0110] Comparative Example 1

[0111] In a dry atmosphere, the raw materials were added to a high energy ball milling tank according to the stoichiometric amount. After ball milling, the precursor powder was heat treated and ground to obtain a Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 halide electrolyte.

[0112] LiNi with a mass ratio of 70% 0.8 Co 0.1 Mn 0.1O2, 1% conductive agent (a conductive agent obtained 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 A solid electrolyte battery was assembled using a halide electrolyte of 29% uniformly mixed in the positive electrode and Li with a particle size of 8 μm in the electrolyte layer. The simplified battery structure is shown in Fig. 9 (the negative electrode is omitted). 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 A solid electrolyte battery was assembled using a halide electrolyte and a lithium-indium alloy for the negative electrode. The simplified battery structure is shown in Fig. 9 (the negative electrode 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 a positive electrode active material and a second halide with a large particle size, and the electrolyte layer 2 contains only the second halide with a large particle size.

[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

[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

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

[0119] ​​Ionic conductivity: The halide powder was pressed into a 10-mm-diameter sheet at 360 MPa. Next, stainless steel sheets were used as ion-blocking electrodes on both sides of the sheet to fabricate an ion-blocking battery. For the EIS test, an electrochemical workstation with a frequency range of 106 to 1 Hz and an amplitude of 5 mV was used. The formula σ = L / (R*A) was used to calculate the ionic conductivity of the electrolyte membrane. In the formula, 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 at the intersection of the curve of the EIS diagram and the real axis was calculated.

[0120] Table 1: Ionic 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 halide reaches 4×10 -4 Scm -1 . As the doping amount of Fe ions increases, the ionic conductivity first increases gradually and then decreases when it reaches the optimum value. When the doping amount a of Fe ions is greater than 0.6 (Comparative Examples 2 and 3), the ionic conductivity of the halide decreases significantly and becomes much lower than the ionic conductivity of the halide of the present invention.

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

[0123] The lithium-ion batteries of the above examples and comparative examples were subjected to a cycle performance test. The test results are shown in Table 2. The test method is as follows.

[0124] The battery fabricated above was repeatedly charged and discharged under an environment of 25°C, and the number of cycles at room temperature when the SOH reached 80% was measured and recorded. The operating voltage range was 2.8V to 4.35V, and the charge and 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 first gradually improves and then gradually decreases. When the doping amount a of Fe ions exceeds 0.6 (Comparative Examples 2 and 3), the cycle characteristics of the battery significantly deteriorate, and furthermore, a short circuit occurs.

[0126] Comparing Example 5 and Examples 9 to 14 with Comparative Example 1, it can be seen that for the same halide, as the particle size increases, the cycle performance of the battery gradually deteriorates.

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

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 the nanometer scale, significantly decreasing the particle size of the halide particles and increasing the specific surface area. By completely or partially replacing the original large-particle halide electrolyte with small-particle halides, the contact between the electrolyte and the positive electrode active material can be increased. As a result, the transport effect of lithium ions is enhanced, and performance degradation due to local contact failure is avoided. Furthermore, pulverization and cracking of the electrolyte that occur during battery cycling can be avoided, improving the cycle performance and energy density of the battery. Therefore, the present invention can effectively solve some practical problems in the prior art and can exhibit high utility value and practical significance.

[0129] The above embodiments illustrate the principles and effects of the present invention and do not limit the present invention. Those skilled in the art can modify or change the above 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 idea disclosed in the present invention shall still be included in the scope of the claims of the present invention.

Explanation of Reference Numerals

[0130] S1~S3: Steps 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, and 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. A lithium-ion battery.

6. The electrolyte layer contains the halide, The lithium-ion battery 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 lithium-ion battery according to Claim 6.

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

Images