Solid electrolyte, lithium ion battery and electronic equipment

Abstract

The invention provides a solid-state electrolyte, a lithium ion battery and electronic equipment, and particularly relates to the technical field of solid-state batteries. The solid electrolyte comprises halide shown in the formula (1), the median particle diameter D50 of at least one part of the halide is 50 nm to 3 microns, and Li < 2 + a > Zr < 1-a > MaCl < 6-x-y > Br < x > I < y > (1), in formula (1), 0 < = a < = 0.6; 0 < = x < = 6, 0 < = y < = 6, and x + y < = 6; m is selected from at least one of V, Cr, Mn, Fe, Co and Ni. When the solid electrolyte is used in the lithium ion battery, lithium ion transmission kinetics is facilitated, pulverization and breakage of electrolyte particles in the circulation process are avoided, and the electrochemical performance of the battery is cooperatively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and in particular to a solid-state electrolyte, an ion battery and an electronic device. Background Art

[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, and have been widely used in electric vehicles, aerospace and portable devices. However, current lithium-ion batteries widely use flammable organic liquid electrolytes, which have serious safety issues and temperature operating limitations. In addition, organic solvents significantly reduce the ionic conductivity of electrolytes at low temperatures. In order to improve the safety and energy density of lithium-ion batteries, non-flammable inorganic solid electrolytes are used to replace liquid electrolytes, which can better adapt to high-voltage positive electrodes and simplify battery structures. Therefore, the development of all-solid-state batteries has become one of the important technical directions for the next generation of batteries.

[0003] In order to promote the development of high-performance all-solid-state batteries, solid electrolytes with high ionic conductivity and wide electrochemical window need to be studied. In addition, in all-solid-state batteries, the solid-solid interface between the electrode and the solid electrolyte plays a vital role in the 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, solid electrolytes are usually added to the positive electrode as ion conductors to enhance the ionic conductivity of the positive electrode. The transport of lithium ions in the positive electrode is highly dependent on the ionic conductivity and particle size of the solid electrolyte, which determines the kinetics of lithium ion transport in the positive electrode and the electrode-electrolyte interface. In addition, the ionic conductivity of the electrolyte layer is affected by the particle size and grain boundary resistance of the solid electrolyte, and the particle size and grain boundary of the solid electrolyte in the positive electrode partially determine the interface contact area and stability to the active material, thereby affecting the interface resistance and lithium ion transport kinetics. Therefore, regulating the particle size of the solid electrolyte plays a vital role in the electrochemical performance of the positive electrode layer and electrolyte layer of the all-solid-state battery.

[0004] The halide solid electrolyte particles currently prepared are relatively large in size. All-solid-state batteries using this electrolyte are easily affected by the internal stress and strain of the battery during the cycle, resulting in the pulverization and rupture of the electrolyte particles, increasing the risk of lithium dendrites penetrating the electrolyte layer. In addition, the larger electrolyte particles have a smaller specific surface area, which is not conducive to the contact between the positive electrode active material and the electrolyte in the positive electrode, seriously affecting the ion transport kinetics, thereby reducing the capacity, rate performance and cycle performance of the all-solid-state battery.

[0005] Therefore, it is necessary to provide a solid electrolyte, a lithium ion battery and an electronic device to solve the above problems. Summary of the invention

[0006] In view of the above shortcomings of the prior art, the present invention provides a solid electrolyte, a lithium ion battery and an electronic device to improve the problem that the solid electrolyte particles have a significant impact on the transport dynamics of ions.

[0007] To achieve the above-mentioned object and other related objects, the present invention provides a solid electrolyte in a first aspect, wherein the solid electrolyte comprises a halide as shown in formula (1), wherein at least a portion of the halide has a median particle size D50 of 50 nm to 3 μm,

[0008] Li 2+a Zr 1-a M a Cl 6-x-y Br x I y (1);

[0009] 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.

[0010] In one example of the present invention, in the formula (1), M is Fe.

[0011] In an example of the present invention, in the formula (1), D50 is 100 nm to 1 μm.

[0012] In an example of the present invention, the D50 is 100 nm to 1 μm.

[0013] A second aspect of the present invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode and an electrolyte layer, wherein the positive electrode comprises a positive electrode active material and any of the above-mentioned solid electrolytes.

[0014] In one example 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.

[0015] In an example of the present invention, the positive electrode further includes a conductive agent, and the mass content of the conductive agent in the positive electrode is 0.05-10%.

[0016] In an example of the present invention, the electrolyte layer includes the halide.

[0017] In one example of the present invention, a median particle size D50 of at least a portion of the halides in the electrolyte layer is 50 nm to 3 μm.

[0018] A third aspect of the present invention provides an electronic device, comprising the above-mentioned lithium-ion battery.

[0019] The solid electrolyte provided by the present invention is a halide, and at least part of the median particle size of the halide is 50nm to 3μm, that is, large-particle halide is nano-processed to obtain small-particle halide, which can increase the specific surface area of ​​the halide particles.

[0020] Using small-particle halides in the positive electrode can increase the contact between the positive electrode active material and the halide, which is beneficial to the transmission of lithium ions, thereby reducing the interface resistance and improving the battery rate and cycle performance. Using small-particle halides in the electrolyte layer can increase the compaction density of the electrolyte layer, avoid the pulverization and rupture of the electrolyte particles, and improve the safety performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a flow chart of a preparation method of a solid electrolyte according to an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of the lithium ion battery of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of the lithium ion battery of the present invention in Example 1;

[0025] Figure 4 is a schematic structural diagram of a lithium-ion battery of the present invention in Example 15;

[0026] Figure 5 is a schematic structural diagram of a lithium-ion battery of the present invention in Example 16;

[0027] Figure 6 is a schematic diagram of the structure of a lithium-ion battery of the present invention in Example 17;

[0028] Figure 7 Schematic diagram of the structure of the lithium ion battery of the present invention in Example 18;

[0029] Figure 8 is a schematic structural diagram of a lithium-ion battery of the present invention in Example 19;

[0030] Fig. 9 Schematic diagram of the structure of the lithium-ion battery of the present invention in comparative example 1. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0033] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0034] As used herein, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0035] Herein, "preferred", "better" and "more preferred" are only used to describe implementation methods or examples with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of the present invention. If multiple "preferred" items appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "preferred" item is independent.

[0036] Herein, “further”, “furthermore”, “particularly”, etc. are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present invention.

[0037] In this article, when it comes to numerical ranges, unless otherwise specified, the distribution of optional values ​​within the numerical range is considered continuous and includes the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as every value between the two numerical endpoints. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined.

[0038] The present invention provides a solid electrolyte, which comprises a halide as shown in formula (1): Li 2+a Zr 1- a M a Cl 6-x-y Br x I y (1);

[0039] Among them, 0 < a ≤ 0.6; 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, x + y ≤ 6; M is selected from at least one of V, Cr, Mn, Fe, Co, Ni.

[0040] In formula (1), M represents a doping element, which can be selected from at least one of Fe, Ni, Co, Mn, Al, Ga, In, that is, M can be any one of the above-listed elements, or a combination of any two or more. Preferably, M is Fe, and the isovalent substitution of Fe in the lattice can improve the ionic conductivity of the electrolyte; a represents the doping amount of element M. 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 element Br, and its value can be any value within the range of 0 to 6. For example, x = 1, 3, or 5, etc.; y represents the doping amount of element I, and its value is any value within the range of 0 to 6. For example, y = 2, 4, or 6, etc. It should be noted that 0 ≤ x + y ≤ 6. When x + y = 0, the halogen element in the halide is only Cl element; when x + y = 6, the halide does not contain Cl element. 3+ The isovalent substitution of Fe in the lattice can improve the ionic conductivity of the electrolyte; a represents the doping amount of element M. 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 element Br, and its value can be any value within the range of 0 to 6. For example, x = 1, 3, or 5, etc.; y represents the doping amount of element I, and its value is any value within the range of 0 to 6. For example, y = 2, 4, or 6, etc. It should be noted that 0 ≤ x + y ≤ 6. When x + y = 0, the halogen element in the halide is only Cl element; when x + y = 6, the halide does not contain Cl element.

[0041] Furthermore, at least part of the halides in the present invention are halides with a median particle size D50 of 50 nm to 3 μm. Further, D50 is 100 nm to 1 μm. For example, 100 nm, 500 nm, 800 nm, or 1 μm, etc. Here, the halide with D50 of 50 nm to 3 μm is defined as the first halide. Then, the halides of the present invention can all be the first halide, or part of them can be the first halide, and the remaining halides are defined as the second halide, and the median particle size of the second halide is greater than 3 μm.

[0042] The halide has the characteristics of high ionic conductivity and high voltage resistance as an electrolyte, and there is good compatibility between the halide and the uncoated oxide cathode active material. Therefore, using the halide of the present invention in a battery can effectively improve the ionic transport kinetics and avoid the space charge effect; and the halide does not contain rare earth metals, which can significantly reduce the cost.

[0043] The inventors found in the research that: due to the small specific surface area of large particle halides, it is not conducive to contact with the cathode active material in the cathode, which will affect the ionic transport kinetics, thereby reducing the capacity, rate performance, and cycle performance of lithium-ion batteries. Therefore, in this application, part of the halides are nano-sized into small particle halides with a median particle size D50 of 50 nm to 3 μm. The halides within this particle size range can increase the specific surface area of the particles, enable better contact between the electrolyte particles and the cathode active material, reduce the interfacial resistance, and improve the rate and cycle performance of the battery.

[0044] The above halides can be obtained by referring to conventional preparation methods in the art. For example, see Figure 1 , the preparation process of the halide comprises the following steps:

[0045] S1. According to the stoichiometric ratio of the chemical formula of the halide, corresponding amounts of compound raw materials containing Li, Zr, and M ions are added into a closed container and mixed to obtain a halide precursor;

[0046] S2, heat-treating the halide precursor, crushing and grinding it to obtain a halide;

[0047] S3, taking at least part of the halide for secondary treatment to obtain a first halide.

[0048] Specifically, the compounds containing Li, Zr, and M ions in step S1 include LiCl, ZrCl4, FeCl3, etc. The mixing method can be selected from conventional methods in the art that can mix the raw materials evenly, such as: one or a combination of mechanical stirring, mechanical shaking, ball milling, and roller milling. Preferably, ball milling is used for mixing, and the rotation speed during ball milling mixing is 100 to 1000 rpm, the mixing time is 0.5 to 3 hours, the diameter of the ball milling zirconium beads is 5 to 20 mm, and the ball-to-material ratio is (20 to 50): 1. The applicant found in the research process that the use of the above-mentioned ball milling conditions can make the raw materials of the solid electrolyte more evenly mixed, and further improve the interface compatibility between the positive electrode active material and the solid electrolyte.

[0049] Further preferably, in the step S1, the rotation speed during ball milling mixing is 300 rpm, the ball milling time is 1 h, the diameter of the ball milling zirconium beads is 10 mm, and the ball-to-material ratio is 30:1.

[0050] The heat treatment in step S2 is to solid-phase sinter the precursor of step S1 in an inert gas atmosphere, wherein the heating rate during the solid-phase sintering is 2-10°C / min, the sintering temperature is 200-500°C, and the sintering time is 2-7 hours. Note: The sintering time is calculated from the time when the temperature is raised to the target sintering temperature.

[0051] Further preferably, the heating rate during the solid phase sintering process is 4-5°C / min, the sintering temperature is 250-350°C, and the sintering time is 3-5 hours. The present invention explores the sintering process and finds that the comprehensive control of the heating rate, sintering temperature and sintering time can enhance the crystallinity of the halide, make the molecular arrangement more orderly, and further improve the ionic conductivity of the halide solid electrolyte.

[0052] After sintering, the sintered product is taken out and crushed and ground to obtain a halide. The present application does not specifically limit the cooling method after sintering. For example, the halide solid electrolyte can be cooled by furnace cooling.

[0053] Since the halide electrolyte particles obtained after sintering are relatively large, which is not conducive to contact with the positive electrode active material, the present application performs step S3, taking at least part of the halide obtained in step S2 for secondary treatment to obtain a small-particle halide (i.e., the first halide) that meets the requirements.

[0054] The secondary treatment method may be one or a combination of ultrasonic dispersion, mechanical vibration, mechanical stirring, ball milling, roller milling, etc. Preferably, mechanical stirring is used, i.e., the halide obtained in step S2 is dispersed in a solvent, and a dispersant is added and stirred until the halide is uniformly dispersed, and the first halide is obtained after drying.

[0055] The solvent in step S3 can be selected from one or a mixture of toluene, chlorobenzene, xylene, dimethyl carbonate, N-methylformamide, n-hexane, glycol dimethyl ether, 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.

[0056] The dispersant in step S3 can be selected from one or more of cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, cetyl trimethyl ammonium sulfonate, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium octyl sulfonate, polyethylene glycol octanol ether, polysorbate, polyoxyethylene stearyl alcohol ether, sodium cocoate, sodium palmitate, sodium olivetate, sodium dodecyl sulfonate, and sodium polyacrylate. Preferably, the dispersant is polyethylene glycol octanol ether.

[0057] During the secondary treatment, the mass ratio of the halide to the solvent is 1:30 to 30:30. Preferably, the mass ratio of the halide to the solvent is 1:20.

[0058] During the secondary treatment, the mass percentage of the dispersant is 0.05-5%, where % 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%.

[0059] The drying method is one or a combination of reduced pressure filtration, vacuum drying, and forced air drying. Preferably, the drying method is vacuum drying.

[0060] See also Figure 2In a second aspect, the present invention provides a lithium-ion battery, which includes a positive electrode 1, a negative electrode 3 and an electrolyte layer 2. The electrolyte layer 2 is arranged between the positive electrode 1 and the negative electrode 3, and is used to transmit lithium ions between the positive and negative electrodes. Among them, the positive electrode 1 includes a positive electrode active material and the solid electrolyte described above. Adding a small-particle halide to the positive electrode 1 can increase the contact between the positive electrode active material and the halide electrolyte, which is beneficial to the transmission of lithium ions. At the same time, the small-particle halide can increase the specific surface area of ​​the electrolyte particles, so that the electrolyte particles have better contact with the positive electrode, reduce the interface resistance, and improve the battery rate and cycle performance.

[0061] 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 can be selected from any one of the positive electrode materials listed above, for example, NCM or LNO or LCO, etc.; the positive electrode active material can also be selected from any two or more combinations of the above, for example, a combination of NCM and LMO, or a combination of NCA and LCO, etc. The specific type of the positive electrode active material can be selected according to actual needs.

[0062] The positive electrode 1 includes a positive electrode active material and a solid electrolyte. Since the median particle size D50 of at least part of the halides in the solid electrolyte is 50nm to 3μm. Then, there are two cases for the positive electrode 1: the positive electrode 1 includes a positive electrode active material and a first halide; or the positive electrode 1 includes a positive electrode active material, a first halide and a second halide. Among them, the ratio of the positive electrode active material and the halide (including the first halide and the second halide) can be set with reference to the ratio of the positive electrode active material and the solid electrolyte in the conventional composite positive electrode. For example, the mass ratio of the positive electrode active material and the halide is (50-75): (20-50).

[0063] 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 can be selected from any one of the above-listed types or a combination of any two or more. 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 in a mass ratio of 1:1.

[0064] The mass percentage of the conductive agent in the positive electrode 1 is 0.05-10%. As an example, the mass percentage of the conductive agent in the positive electrode can be 0.05%, 1%, 5%, 8% or 10%.

[0065] See also Figure 2In one embodiment, the electrolyte layer 2 includes halides in the solid electrolyte, which may be all halides (second halides) that have not been treated for the second time, or all first halides with a median particle size of 50 nm to 3 μm, or a combination of the first halide and the second halide. Preferably, the electrolyte layer 2 at least partially includes the first halide. Since the particle size of the first halide is small, adding a small-particle halide to the electrolyte layer 2 can increase the compaction density of the electrolyte layer 2, avoid pulverization and rupture of the electrolyte particles, and improve the safety performance of the battery. It should be noted that when the electrolyte layer 2 includes 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 include the second halide, and it is entirely composed of the first halide.

[0066] The negative electrode of the lithium-ion battery of the present application is conventionally understood in the art: a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material, and 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. Among them, graphite materials may be listed as natural graphite (block graphite, flake graphite, earthy graphite), artificial graphite (single crystal graphite, polycrystalline graphite, pyrolytic graphite, graphite fiber, etc.); silicon materials include but are not limited to elemental silicon, silicon oxides, etc.

[0067] The lithium-ion battery can be assembled into an all-solid-state soft-pack battery by laminating, packaging, hot pressing and cold pressing the positive electrode, electrolyte layer and negative electrode sheet prepared above using methods commonly used in the art.

[0068] The present invention also provides an electronic device, which comprises the lithium ion battery described above. 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.

[0069] The electronic devices of the present invention include, but are not limited to, mobile phones, tablets, laptop computers, electric toys, battery cars, new energy vehicles, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles and spacecraft, etc. New energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.

[0070] The technical scheme of the present invention is described in detail below through several specific examples and comparative examples. It should be clear to those skilled in the art that the examples are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the examples are all commercially available.

[0071] Example 1

[0072] This embodiment provides a solid electrolyte, which includes a halide Li2ZrCl5Br 0.5 I 0.5 , wherein at least part of the halide is a first halide having a median particle size D50 of 100 nm, and the rest is a second halide having a median particle size of 8 μm.

[0073] The halide preparation process is as follows:

[0074] In a dry atmosphere, the raw materials LiCl and ZrCl4 are added into a high-energy ball mill according to a stoichiometric ratio, and a precursor is obtained after ball milling; the precursor powder is heat-treated and ground into powder to obtain Li2ZrCl5Br with a particle size of 8 μm. 0.5 I 0.5 Halide. The obtained halide was added to a certain amount of xylene solution at a mass ratio of halide: solvent = 1:20, and 1% polyethylene glycol octanol ether was added, mechanically stirred until the mixture was uniform, and vacuum dried to obtain Li2ZrCl5Br with a particle size of 100 nm. 0.5 I 0.5 Small particle size halide (first halide).

[0075] Positive electrode: 70% LiNi 0.8 Co 0.1 Mn 0.1 O2, 1% conductive agent (super-P and VGCF mixed conductive agent with a mass ratio of 1:1), 29% Li2ZrCl5Br with a particle size of 100nm 0.5 I 0.5 Small particle size halides are mixed into a uniform positive electrode.

[0076] Electrolyte layer, 8μm particle size Li2ZrCl5Br 0.5 I 0.5 halide.

[0077] Negative electrode: Lithium-indium alloy as negative electrode

[0078] Lithium-ion battery assembly: The positive electrode, electrolyte layer and negative electrode prepared above are stacked, packaged, hot pressed and cold pressed to assemble into a fully solid-state soft-pack battery. The battery structure is simplified. Figure 3 (Negative electrode omitted).

[0079] Figure 3 The material composition of the positive electrode 1 and the electrolyte layer 2 in this embodiment is clearly shown. Figure 3 It can be seen that the positive electrode 1 includes a uniformly mixed positive electrode active material and a first halide with a small particle size, and the electrolyte layer 2 only includes a second halide with a large particle size.

[0080] Example 2

[0081] The difference between this embodiment and embodiment 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 .

[0082] Example 3

[0083] The difference between this embodiment and embodiment 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 .

[0084] Example 4

[0085] The difference between this embodiment and embodiment 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 .

[0086] Example 5

[0087] The difference between this embodiment and embodiment 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 .

[0088] Example 6

[0089] The difference between this embodiment and embodiment 1 is that the chemical formula of the halide is Li 2.4 Zr 0.6 Fe 0.4 Cl5Br 0.5 I 0.5 .

[0090] Example 7

[0091] The difference between this embodiment and embodiment 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 .

[0092] Example 8

[0093] The difference between this embodiment and embodiment 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 .

[0094] Example 9

[0095] The difference between this embodiment and embodiment 5 is that the particle size of the first halide is 50 nm.

[0096] Example 10

[0097] The difference between this embodiment and embodiment 5 is that the particle size of the first halide is 300 nm.

[0098] Embodiment 11

[0099] The difference between this embodiment and embodiment 5 is that the particle size of the first halide is 500 nm.

[0100] Example 12

[0101] The difference between this embodiment and embodiment 5 is that the particle size of the first halide is 750 nm.

[0102] Example 13

[0103] The difference between this embodiment and embodiment 5 is that the particle size of the first halide is 1 μm.

[0104] Embodiment 14

[0105] The difference between this embodiment and embodiment 5 is that the particle size of the first halide is 3 μm.

[0106] Embodiment 15

[0107] The difference between this embodiment and embodiment 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 Li particles with a size of 100 nm 2.35Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The remaining steps are the same as those in Example 5. The simplified battery structure is shown in Figure 4 (Negative electrode omitted).

[0108] Figure 4 The material composition of the positive electrode 1 and the electrolyte layer 2 in this embodiment is clearly shown. Figure 4 It can be seen from the figure that the positive electrode 1 includes 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 only includes the second halide with a large particle size.

[0109] Example 16

[0110] The difference between this embodiment and embodiment 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 Halide electrolyte and Li particles with a size of 100 nm 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The remaining steps are the same as those in Example 5. The simplified battery structure is shown in Figure 5 (Negative electrode omitted).

[0111] Figure 5 The material composition of the positive electrode 1 and the electrolyte layer 2 in this embodiment is clearly shown. Figure 5 It can be seen that the positive electrode 1 includes a uniformly mixed positive electrode active material and a first halide with a small particle size, and the electrolyte layer 2 includes a first halide with a small particle size and a second halide with a large particle size.

[0112] Embodiment 17

[0113] The difference between this embodiment and embodiment 5 is that the electrolyte layer 2 is Li with a particle size of 100 nm. 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Small particle size halide electrolyte. The remaining steps are the same as in Example 5. The simplified battery structure is shown in Figure 6 (Negative electrode omitted).

[0114] Figure 6The material composition of the positive electrode 1 and the electrolyte layer 2 in this embodiment is clearly shown. Figure 6 It can be seen that the positive electrode 1 includes a uniformly mixed positive electrode active material and a first halide with a small particle size, and the electrolyte layer 2 is entirely composed of the first halide with a small particle size.

[0115] Embodiment 18

[0116] The difference between this embodiment and embodiment 15 is that the electrolyte layer 2 is Li with a particle size of 8 μm and a mass ratio of 1:1. 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Halide and 100nm Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The composition of the small particle size halide, the remaining steps are the same as in Example 15, and the simplified battery structure is shown in Figure 7 (Negative electrode omitted).

[0117] Figure 7 The material composition of the positive electrode 1 and the electrolyte layer 2 in this embodiment is clearly shown. Figure 7 It can be seen that the positive electrode 1 includes 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 includes a uniformly dispersed first halide with a small particle size and a second halide with a large particle size.

[0118] Embodiment 19

[0119] The difference between this embodiment and embodiment 15 is that the electrolyte layer 2 is Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Small particle size halide, the remaining steps are the same as Example 15, the simplified battery structure is shown in Figure 8 (Negative electrode omitted).

[0120] Figure 8 The material composition of the positive electrode 1 and the electrolyte layer 2 in this embodiment is clearly shown. Figure 8 It can be seen that the positive electrode 1 includes 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 only includes the first halide with a small particle size.

[0121] Comparative Example 1

[0122] In a dry atmosphere, the raw materials were added into a high-energy ball mill according to stoichiometric amounts. After ball milling, the precursor powder was heat treated and ground into powder to obtain Li 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 Halide electrolytes.

[0123] The mass ratio of LiNi is 70% 0.8 Co 0.1 Mn 0.1 O2, 1% conductive agent (super-P and VGCF mixed conductive agent with a mass ratio of 1:1), 29% Li with a particle size of 8 μm 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The halide electrolyte is mixed into a uniform positive electrode. 2.35 Zr 0.65 Fe 0.35 Cl5Br 0.5 I 0.5 The halide electrolyte is the electrolyte layer, the lithium-indium alloy is the negative electrode, and the all-solid-state battery is assembled. The simplified battery structure diagram can be seen in Fig. 9 (Negative electrode omitted).

[0124] Fig. 9 The material composition of the positive electrode 1 and the electrolyte layer 2 in this comparative example is clearly shown. Fig. 9 It can be seen that the positive electrode 1 includes a uniformly mixed positive electrode active material and a second halide with a large particle size, and the electrolyte layer 2 only includes a second halide with a large particle size.

[0125] Comparative Example 2

[0126] 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 .

[0127] Comparative Example 3

[0128] 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 .

[0129] The first halide prepared in each embodiment and comparative example was tested for ion conductivity. The test results are shown in Table 1. The test method is as follows:

[0130] Ion conductivity: The halide powder was pressed into a sheet with a diameter of 10 mm at 360 MPa, and then stainless steel sheets were placed on both sides of the sheet as ion blocking electrodes to make an ion blocking cell. The EIS test was performed using an electrochemical workstation with a frequency range of 10 6 ~1Hz, amplitude 5mV, use the formula σ=L / (R*A) to calculate the ionic conductivity of the electrolyte membrane, L is the thickness of the electrolyte membrane, A is the effective area of ​​the electrolyte membrane, R is the bulk resistance of the electrolyte membrane, and the resistance value is taken at the intersection of the EIS curve and the real axis.

[0131] Table 1: Ionic conductivity and particle size of the first halide electrolyte in each embodiment and comparative example

[0132]

[0133]

[0134] It can be concluded from Table 1 that when the doping amount a of Fe ions in the halides of Examples 1 to 8 is 0 to 0.6, the ionic conductivity of the halides reaches 4×10 -4 S cm -1 , and with the increase of the Fe ion doping amount, the ionic conductivity first gradually increases, and when it reaches the optimum, it decreases accordingly; when the Fe ion doping amount a is greater than 0.6 (Comparative Examples 2 and 3), the ionic conductivity of the halide decreases significantly, which is much lower than the ionic conductivity of the halide in the present application.

[0135] By comparing Example 5, Examples 9 to 14 and Comparative Example 1, it can be seen that for the same type of halide, as the particle size increases, the ion conductivity increases accordingly.

[0136] The lithium ion batteries of the above embodiments and comparative examples were subjected to cycle performance tests. The test results are shown in Table 2. The test method is as follows:

[0137] The battery prepared above was subjected to cyclic charge and discharge at 25°C, and the number of normal temperature cycles when the SOH was 80% was measured and recorded. The operating voltage range was 2.8V to 4.35V, and the charge and discharge rate was 1C / 1C.

[0138]

[0139]

[0140] It can be seen from Table 2 that in Examples 1 to 8, as the amount of Fe ion doping in the halide increases, the cycle performance of the lithium ion battery first gradually increases and then gradually decreases; when the Fe ion doping amount a is greater than 0.6 (Comparative Examples 2 and 3), the cycle performance of the battery is greatly reduced, and even a short circuit phenomenon occurs.

[0141] By comparing Example 5, Examples 9 to 14 and Comparative Example 1, it can be concluded that for the same type of halide, as the particle size increases, the cycle performance of the battery gradually decreases.

[0142] By comparing Example 5, Examples 15 to 19 and Comparative Example 1, it can be concluded that adding at least a portion of small-particle halide to the positive electrode and / or the electrolyte layer can significantly improve the cycle performance of the lithium-ion battery.

[0143] The present invention will Li 2+a Zr 1-a Fe a Cl 6-x-y Br x I y The halide is subjected to secondary treatment to nanosize its particle size, which greatly reduces the particle size of the halide particles and makes them have a larger specific surface area. The small-particle halide completely or partially replaces the original large-particle halide electrolyte, which can increase the contact between the electrolyte and the positive electrode active material, enhance the transmission effect of lithium ions, avoid performance deterioration caused by local poor contact, and avoid electrolyte pulverization and rupture during battery cycling, thereby improving the battery's cycle performance and energy density. Therefore, the present invention effectively overcomes some practical problems in the prior art and has a high utilization value and use significance.

[0144] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A solid electrolyte, characterized in that The solid electrolyte comprises a halide as shown in the following formula (1), at least a portion of the halide has a median particle size D50 of 50 nm to 3 μm, and Li 2+a Zr 1-a M a Cl 6-x-y Br x I y (1) Among them, 0 < a ≤ 0.6; 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, x + y ≤ 6; M is selected from at least one of V, Cr, Mn, Fe, Co, and Ni.

2. The solid electrolyte according to claim 1, characterized in that In the formula (1), M is Fe.

3. The solid electrolyte according to claim 2, characterized in that In the formula (1), 0.01 ≤ a ≤ 0.

5.

4. The solid electrolyte according to any one of claims 1 to 3, characterized in that The D50 is 100 nm to 1 μm.

5. A lithium ion battery comprising a positive electrode, a negative electrode and an electrolyte layer, characterized in that: The positive electrode includes a positive electrode active material and the solid electrolyte according to any one of claims 1-4.

6. The lithium-ion battery according to claim 5, characterized in that: The electrolyte layer includes the halide.

7. The lithium-ion battery according to claim 6, characterized in that: The median particle size D50 of at least a part of the halide in the electrolyte layer is 50 nm to 3 μm.

8. An electronic device, characterized in that: A lithium ion battery according to any one of claims 4-7.

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