LiZnCl4 derivatives in the space group Pmn21 as lithium superionic conductors, solid electrolytes, and coating layers for lithium metal and lithium ion batteries

Abstract

A solid-state lithium-ion electrolyte of a lithium zinc chloride derivative compound having a crystalline form in the space group Pmn21 is provided as a material for conducting lithium ions. The lithium aluminum chloride derivative compound has an activation energy of 0.15-0.40 eV and a conductivity of 0.01-15 mS / cm at 300 K. Compounds having specific chemical formulas are provided, and methods for modifying the material by including heterovalent ions are disclosed. Lithium batteries containing the composite lithium-ion electrolyte and electrodes containing the lithium aluminum chloride derivative compound are also provided.

Description

[Technical Field]

[0001] Parties to the Joint Research Agreement This disclosure is the result of collaborative research conducted under a Cooperative Research Agreement between Toyota Motor Engineering and Manufacturing North America, Inc., 6565 Headquarters Dr. W1-3C, Plano, Texas 75024, and the University of Maryland, College Park, 2130 Mitchell Bldg., 7999 Regents Dr., College Park, Maryland, 20742.

[0002] Field of Disclosure The present disclosure relates to novel LiZnCl4 derivative compounds that exhibit high lithium ion conductivity and have a crystal structure in the space group Pmn21, and that are useful as solid electrolytes, electrode elements, and / or electrode coatings for Li-ion and Li-metal batteries. [Background technology]

[0003] background Lithium-ion batteries have traditionally dominated the market for portable electronic devices. However, conventional Li-ion batteries contain flammable organic solvents as components of the electrolyte, and this flammability poses a significant safety risk that may limit or prevent the use of Li-ion batteries in large-scale energy storage devices.

[0004] Replacing the flammable organic liquid electrolyte with a solid Li-conducting phase can mitigate this safety issue and provide further benefits such as improved mechanical and thermal stability. The main function of the solid Li-conducting phase, usually referred to as a solid Li-ion conductor or solid electrolyte, is to block the direct transport of electrons between the electrodes in the battery while allowing Li to pass through the battery during discharge. + Ions are transferred from the anode to the cathode, and Li + The purpose is to conduct ions from the cathode side to the anode side.

[0005] Lithium batteries constructed with non-aqueous electrolytes are also known to form dendritic lithium metal structures that protrude from the anode to the cathode during repeated discharge and charge cycles. If these dendritic structures protrude into the cathode and short-circuit, the battery energy can be rapidly released, potentially igniting the organic solvent.

[0006] Therefore, much interest and effort has been focused on discovering new solid-state Li-ion conducting materials that will lead to all-solid-state lithium batteries. Research in the past few decades has mainly focused on ion-conducting oxides, such as LISICON (Li 14 ZnGeO 16 ), NASICON(Li 1.3 Al 0.3 Ti 1.7 (PO4)3), perovskites (e.g., La 0.5 Li 0.5 TiO3), garnet (Li7La3Zr2O 12 ) and LiPON (e.g., Li 2.88 PO 3.73 N 0.14 ), and sulfides, e.g., Li3PS4, Li7P3S 11 and LGPS(Li 10 GeP2S 12 ) was focused on. Summary of the Invention [Problem to be solved by the invention]

[0007] Recent developments have led to solid-state Li-ion conductors with conductivities of 1–10 mS / cm, comparable to those of liquid-phase electrolytes, but the discovery of new solid Li-ion conductors is of great interest.

[0008] Effective lithium-ion solid conductors have high Li at room temperature. + Generally, Li + The conductivity is 10 -6 S / cm or more. +The migration activation energy of the conductor must be low for use over a range of operating temperatures likely to be encountered in the application environment. Furthermore, the material must have good stability against chemical, electrochemical, and thermal degradation. Unlike many conventionally used non-aqueous solvents, the solid conductor material must be stable against electrochemical decomposition reactions with the anode and cathode chemical compositions. The material must also have low grain boundary resistance for use in solid-state batteries. Ideally, the material should be easy to synthesize and inexpensive.

[0009] Li / Li + With a standard redox potential of -3.04 V, Li metal is one of the strongest reducing agents available. Therefore, Li metal can reduce most known cationic species to lower oxidation states. This strong reduction ability allows the lithium metal anode to be used in solid Li containing cationic species different from lithium ions. + When in contact with a conductor, lithium reduces cationic species to a lower oxidation state, degrading the solid conductor.

[0010] Therefore, many previously known solid Li-ion conductors suffer from stability problems when in contact with a Li metal anode.

[0011] The inventors of this application are +They have been investigating lithium compounds that can be used as conductors, and their previous research results have been published in U.S. Application No. 15 / 626696 (June 19, 2017), U.S. Application No. 15 / 805672 (November 7, 2017), U.S. Application No. 16 / 013495 (June 20, 2018), U.S. Application No. 16 / 114946 (August 28, 2018), U.S. Application No. 16 / 142217 (September 26, 2018), U.S. Application No. No. 16 / 144157 (September 27, 2018), U.S. Application No. 16 / 153335 (October 10, 2018), U.S. Application No. 16 / 155349 (October 9, 2018), U.S. Application No. 16 / 264294 (January 31, 2019), U.S. Application No. 16 / 570811 (September 13, 2019), and U.S. Application No. 16 / 570888 (September 13, 2019). Research efforts continue to discover additional materials that offer maximum efficiency, high stability, low cost, and ease of handling and manufacturing.

[0012] It is therefore an object of the present application to identify further materials that are poor electronic conductors but have high Li-ion conductivity, and are suitable as solid electrolytes and / or electrode elements for lithium-ion and lithium metal batteries.

[0013] It is a further object of the present application to provide solid-state lithium-ion and / or lithium metal batteries that include materials that are poor electronic conductors but have high Li-ion conductivity. [Means for solving the problem]

[0014] Summary of the Embodiments These and other objects are provided by embodiments of the present application. A first embodiment provides a solid lithium-ion electrolyte, the solid lithium-ion electrolyte comprising: comprising at least one material selected from the group of materials consisting of compounds having chemical formulas (I), (II), (III) and (IV), Li x-y (M1) y ZnCl4···(I) wherein y is a number greater than 0 and less than 2, x is a value such that the chemical formula is charge neutral, and M1 is at least one element selected from the elements of Groups 1, 2, and 13, and is different from Li; Li x Zn 1-z (M2) z Cl4···(II) wherein z is a number greater than 0 and less than 1, x is a value such that chemical formula (II) is charge neutral, M2 is at least one element selected from the elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; Li x ZnCl 4-h (X) h (III) wherein h is greater than 0 and less than 4, x is a value such that chemical formula (III) is charge neutral, and X is at least one element selected from the elements of Groups 16 and 17, and is different from Cl; Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV) In the formula, m is a number of 0 to less than 2, n is a number of 0 to less than 1, o is a number of 0 to less than 4, and x is a value that makes chemical formula (IV) charge neutral, with the proviso that at least two of m, n, and o are not 0; The compounds having chemical formulas (I), (II), (III) and (IV) comprise a crystal lattice structure having an orthorhombic phase of space group Pmn21, However, the content of M1, M2 and / or X is such that the compound maintains its Pmn21 structure.

[0015] In one aspect of the first embodiment, the lithium ions (Li) of the solid lithium ion electrolyte having the chemical formulas (I) to (IV) + ) The conductivity is 0.1 to 15 mS / cm at 300K.

[0016] In another aspect of the first embodiment, the activation energy of the complexes having chemical formulas (I) to (IV) is 0.15 to 0.40 eV.

[0017] A second embodiment provides a solid-state lithium battery, comprising: an anode; a cathode; a solid-state lithium-ion electrolyte disposed between the anode and the cathode; The solid lithium ion electrolyte comprises at least one material selected from the group of materials consisting of compounds having chemical formulas (I), (II), (III), and (IV), Li x-y (M1) y ZnCl4···(I) wherein y is a number greater than 0 and less than 2, x is a value such that the chemical formula is charge neutral, and M1 is at least one element selected from the elements of Groups 1, 2, and 13, and is different from Li; Li x Zn 1-z (M2) z Cl4···(II) wherein z is a number greater than 0 and less than 1, x is a value such that chemical formula (II) is charge neutral, M2 is at least one element selected from the elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; Li x ZnCl 4-h (X) h (III) wherein h is greater than 0 and less than 4, x is a value such that chemical formula (III) is charge neutral, and X is at least one element selected from the elements of Groups 16 and 17, and is different from Cl; Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV) In the formula, m is a number of 0 to less than 2, n is a number of 0 to less than 1, o is a number of 0 to less than 4, and x is a value that makes chemical formula (IV) charge neutral, with the proviso that at least two of m, n, and o are not 0; The compounds having chemical formulas (I), (II), (III) and (IV) comprise a crystal lattice structure having an orthorhombic phase of space group Pmn21, However, the content of M1, M2 and / or X is such that the compound maintains its Pmn21 structure.

[0018] The lithium battery of the second embodiment may be a lithium metal battery or a lithium ion battery.

[0019] A third embodiment provides an electrode for a solid-state lithium battery, the electrode comprising: A current collector; an electrode active layer provided on the current collector; The electrode active layer comprises at least one compound selected from the group consisting of compounds having chemical formulas (I), (II), (III), and (IV), Li x-y (M1) y ZnCl4···(I) wherein y is a number greater than 0 and less than 2, x is a value such that the chemical formula is charge neutral, and M1 is at least one element selected from the elements of Groups 1, 2, and 13, and is different from Li; Li x Zn 1-z (M2) z Cl4···(II) wherein z is a number greater than 0 and less than 1, x is a value such that chemical formula (II) is charge neutral, M2 is at least one element selected from the elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; Li x ZnCl 4-h (X) h (III) wherein h is greater than 0 and less than 4, x is a value such that chemical formula (III) is charge neutral, and X is at least one element selected from the elements of Groups 16 and 17, and is different from Cl; Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV) In the formula, m is a number of 0 to less than 2, n is a number of 0 to less than 1, o is a number of 0 to less than 4, and x is a value that makes chemical formula (IV) charge neutral, with the proviso that at least two of m, n, and o are not 0; The compounds having chemical formulas (I), (II), (III) and (IV) comprise a crystal lattice structure having an orthorhombic phase of space group Pmn21, However, the content of M1, M2 and / or X is such that the compound maintains its Pmn21 structure.

[0020] A fourth embodiment provides an electrode for a solid-state lithium battery, the electrode comprising: A current collector; an electrode active layer provided on the current collector; a coating layer provided on the electrode active layer, The coating layer provided on the electrode active layer contains at least one compound selected from the group consisting of compounds having chemical formulas (I), (II), (III), and (IV), Li x-y (M1) y ZnCl4···(I) wherein y is a number greater than 0 and less than 2, x is a value such that the chemical formula is charge neutral, and M1 is at least one element selected from the elements of Groups 1, 2, and 13, and is different from Li; Li x Zn 1-z (M2) z Cl4···(II) wherein z is a number greater than 0 and less than 1, x is a value such that chemical formula (II) is charge neutral, M2 is at least one element selected from the elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; Li x ZnCl 4-h (X) h (III) wherein h is greater than 0 and less than 4, x is a value such that chemical formula (III) is charge neutral, and X is at least one element selected from the elements of Groups 16 and 17, and is different from Cl; Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV) In the formula, m is a number of 0 to less than 2, n is a number of 0 to less than 1, o is a number of 0 to less than 4, and x is a value that makes chemical formula (IV) charge neutral, with the proviso that at least two of m, n, and o are not 0; The compounds having chemical formulas (I), (II), (III) and (IV) comprise a crystal lattice structure having an orthorhombic phase of space group Pmn21, However, the content of M1, M2 and / or X is such that the compound maintains its Pmn21 structure.

[0021] Solid-state lithium batteries including the electrodes and / or electrolytes of various embodiments and aspects are also provided. The solid-state lithium batteries may be lithium metal batteries or lithium ion batteries.

[0022] The foregoing has been provided as a general description and summary of the invention and is not intended to be limiting unless otherwise specified. Presently preferred embodiments and further advantages will be best understood by referring to the following detailed description taken in conjunction with the accompanying drawings.

[0023] This patent or application document contains at least one color drawing. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 shows the crystal structure of Li2ZnCl4 in space group Pmn21. [Figure 2] FIG. 1 shows an XRD analysis of the crystal structure of Li2ZnCl4 in space group Pmn21. [Figure 3] This is a table listing the peak positions and intensities of peaks having a relative intensity of 1 or more compared to the peak with the maximum intensity in the XRD analysis of Li2ZnCl4 in FIG. [Figure 4] FIG. 1 shows the crystal structure of Li1.5Zn0.5Al0.5Cl4 in the space group Pmn21. [Figure 5] FIG. 1 shows an XRD analysis of the crystal structure of Li1.5Zn0.5Al0.5Cl4 in space group Pmn21. [Figure 6] This is a table listing the peak positions and intensities of peaks having a relative intensity of 1 or more compared to the peak with the maximum intensity in the XRD analysis of Li1.5Zn0.5Al0.5Cl4 in FIG. 5. [Figure 7] FIG. 1 shows the crystal structure of Li1.25Al0.75Zn0.25Cl4 in space group Pmn21. [Figure 8] FIG. 1 shows an XRD analysis of the crystal structure of Li1.25Al0.75Zn0.25Cl4 in space group Pmn21. [Figure 9] 9 is a table showing the peak positions and intensities of peaks having a relative intensity of 1 or more compared to the peak with the maximum intensity in the XRD analysis of Li1.75Al0.75Zn0.25Cl4 in FIG. 8. [Figure 10] 1 is an Arrhenius plot showing the Li-ion diffusivity D in Li2ZnCl4 obtained from AIMD simulations. [Figure 11]FIG. 1 shows the Li-ion probability density of Li2ZnCl4 obtained from AIMD simulations. [Figure 12] FIG. 1 shows the Li-ion probability density of Li1.5Zn0.5Al0.5Cl4 obtained from AIMD simulations. [Figure 13] FIG. 1 shows the Li-ion probability density of Li1.25Al0.75Zn0.25Cl4 obtained from AIMD simulations. DETAILED DESCRIPTION OF THE INVENTION

[0025] DESCRIPTION OF THE PREFERRED EMBODIMENT Throughout this specification, the terms "electrochemical cell" and "battery" may be used interchangeably unless the context of this specification clearly distinguishes electrochemical cells from batteries, and the terms "solid electrolyte" and "solid ionic conductor" may be used interchangeably unless expressly specified otherwise.

[0026] Valid Li + The structural properties of the conducting crystal lattice were compared with those of the known Li + Ionic conductor Li 10 GeP2S 12 and Li7P3S 11 The sulfur sublattices in both materials were shown to closely conform to a bcc lattice structure. + Li between lattice sites + Ion hopping has been shown to offer the lowest activation energy pathway.

[0027] The present inventors are currently investigating new lithium composite compounds to identify materials with properties that can function as solid electrolytes in solid-state lithium batteries. In the course of this research and endeavor, the present inventors have developed and implemented methods to identify composite materials with chemical and structural properties that the present inventors have determined to be indicative of lithium ion conductivity suitable for use as solid electrolytes and electrodes adjacent to the solid electrolyte for lithium ion batteries.

[0028] A material must meet several specific criteria to be practical as a solid electrolyte. First, the material must have a low thermal conductivity, typically 10 -6 The material must have a desirable Li-ion conductivity of 100 S / cm or higher. Second, the material must have good stability against chemical, electrochemical, and thermal degradation. Third, the material must have low grain boundary resistance for use in solid-state batteries. Fourth, the material must be easy to synthesize and inexpensive.

[0029] The criterion for this method is that the material must have a temperature of typically 10°C at room temperature in order to be practical as a solid electrolyte. -6 It is necessary to exhibit desirable Li-ion conductivities of 0.1 S / cm or higher. Therefore, ab initio molecular dynamics simulation studies were applied to calculate the diffusivity of Li ions in the lattice structure of selected silicate materials. To accelerate the simulations, calculations were performed at high temperatures to examine the effect of excess Li or Li vacancies. Aliovalent substitution of cations or anions was evaluated to create excess Li or Li vacancies. Thus, Li vacancies were created by partially substituting Si with aliovalent cation species, while compensating for charge neutrality with Li vacancies or excess Li. For example, Li 10 Si2PbO 10 By substituting 50% of Si with P, Li9PSiPbO 10 Form.

[0030] The diffusion coefficient at 300 K was determined according to equation (I).

[0031] D=D0exp(-E a / k b T)...Equation (I) In the formula, D0, E a and k b are the pre-exponential factor, activation energy and Boltzmann constant, respectively. The conductivity is related to the diffusivity calculated according to equation (II):

[0032] σ=D 300 ρe 2 / k b T...Equation (II) where ρ is the volume density of Li ions and e is the unit charge.

[0033] The anionic lattices of Li-ion conductors have been shown to conform to specific lattice types (see Nature Materials, 14, 2015, 2016). + The anionic lattice of the ionic conductor is Li, which is known to have high conductivity. + Compared to the anionic lattice of an ionic conductor.

[0034] Therefore, according to the anion lattice comparison method developed by the inventors for this purpose and described in co-pending U.S. Application No. 15 / 597651 (May 17, 2017), the lattices of selected lithium aluminum chloride derivative compounds were compared and evaluated with Li-containing compounds reported in the Inorganic Crystal Structure Database (FIZ Karlsruhe ICSD https: / / icsd.fiz-karlsruhe.de) to compare the lattices of these compounds with known Li-ion conductors.

[0035] According to the anion lattice comparison method described in co-pending U.S. application Ser. No. 15 / 597,651, a set of atomic coordinates for a compound lattice structure can be converted to a set of coordinates for an anion-only lattice. Anions in the lattice are replaced with anions from a comparison material, and the resulting unit cell size is modified. X-ray diffraction data for the modified anion-only lattice can be simulated, and an nx2 matrix can be generated from the simulated diffraction data. Quantitative values for structural similarity can be derived from the nx2 matrix.

[0036] The purpose of the anion lattice comparison is to + From this research, the compounds described in the following embodiments are considered to be the most promising compounds for solid Li + It was determined to be potentially suitable as a conductor.

[0037] First-principles molecular dynamics (AIMD) simulations were then applied to predict the conductivity of the target lithium aluminum chloride derivative compounds. The initial structure was statically relaxed and set to an initial temperature of 100 K. The structure was then heated to the target temperature (550-650 K) at a constant rate by varying the rate over a period of 2 ps. The total time for the AIMD simulation ranged from 400 to 1000 ps. Typical examples of the calculated diffusivities (as a function of temperature) are shown in Figure 11. Li at different temperatures from 500 to 650 K. + The diffusion rate follows the Arrhenius law.

[0038] By applying equation (I) above, the diffusivity at 300K can be determined and then the conductivity can be determined using the relationship between conductivity and diffusivity in equation (II).

[0039] Thus, a first embodiment provides a solid lithium-ion electrolyte, which comprises: comprising at least one material selected from the group of materials consisting of compounds having chemical formulas (I), (II), (III) and (IV), Li x-y(M1) y ZnCl4···(I) wherein y is a number greater than 0 and less than 1, x is a value such that the chemical formula is charge neutral, and M1 is at least one element selected from the elements of Groups 1, 2, and 13, and is different from Li; Li x Zn 1-z (M2) z Cl4···(II) wherein z is a number greater than 0 and less than 1, x is a value such that chemical formula (II) is charge neutral, M2 is at least one element selected from the elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; Li x ZnCl 4-h (X) h (III) wherein h is greater than 0 and less than 4, x is a value such that chemical formula (III) is charge neutral, and X is at least one element selected from the elements of Groups 16 and 17, and is different from Cl; Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV) In the formula, m is a number of 0 to less than 2, n is a number of 0 to less than 1, o is a number of 0 to less than 4, and x is a value that makes chemical formula (IV) charge neutral, with the proviso that at least two of m, n, and o are not 0; The compounds having chemical formulas (I), (II), (III) and (IV) comprise a crystal lattice structure having an orthorhombic phase of space group Pmn21, However, the content of M1, M2 and / or X is such that the compound maintains its Pmn21 structure.

[0040] The compounds having chemical formulas (I)-(IV) are derivatives of Li2ZnCl4 with a crystal lattice structure in the orthorhombic phase of space group Pmn21. The crystal lattice structure of Li2ZnCl4 in space group Pmn21 is shown in Figure 1, and the calculated X-ray diffraction (XRD) pattern based on Cu-Kα radiation with a wavelength of 1.54184 Å for this space group is shown in Figure 2. Peak positions and relative intensities are shown in Figure 3.

[0041] The present inventors have found that by substituting element M1 with Li, element M2 with Zn, and element X with Cl in Li2ZnCl4 of space group Pmn21, the Li-ion mobility can be improved, the Li-ion density in the crystal lattice can be increased, and an efficient Li-ion conductor useful as a solid electrolyte for lithium batteries can be provided.

[0042] The degree of doping or substitution that can be performed on Li2ZnCl4 while maintaining the Pmn21 morphology varies depending on the element used as the dopant. In general, the more similar the ionic radii and electronic structures, the greater the molar amount of dopant that can be used without significantly altering the crystal morphology. The simulation methods applied and described herein can be used to determine the degree of doping with a particular element without altering the basic Pmn21 crystal structure.

[0043] For example, as described in the Examples, Al 3+ Zn 2+ The Pmn21 structure can be maintained by doping with a ratio of 0.75Al / 0.25Zn.

[0044] In a further aspect of the first embodiment, simulation studies have shown that the solid electrolytes having chemical formulas (I)-(IV) have a conductivity of lithium ions (Li) of 0.01-10 mS / cm, preferably 0.1-15 mS / cm at 300 K. + ) conductivity.

[0045] The activation energy of the solid electrolytes having the chemical formulas (I) to (IV) may be 0.15 to 0.40 eV.

[0046] The synthesis of the composite materials of the above-described embodiments can be achieved by solid-state reactions between selected stoichiometric amounts of precursor materials. Exemplary methods of solid-state synthesis are described, for example, in the following publications: i) Monatshefte fur Chemie, 100, 295-303, 1969; ii) Journal of Solid State Chemistry, 128, 1997, 241; iii) Zeitschrift fur Naturforschung B, 50, 1995, 1061; iv) Journal of Solid State Chemistry, 130, 1997, 90; v) Journal of Alloys and Compounds, 645, 2015, S174; and vi) Z. Naturforsch. 51b, 1996, 52, 5.

[0047] In further embodiments, the present application includes solid-state lithium-ion batteries containing the above-described solid electrolytes. These embodiments of solid-state batteries, including metal-metal solid-state batteries, have higher charge / discharge rates and higher power densities than traditional batteries, and can provide high power and energy densities.

[0048] Thus, a further embodiment provides a solid state lithium battery comprising: an anode; a cathode; a solid-state lithium-ion electrolyte disposed between the anode and the cathode; The solid lithium ion electrolyte comprises at least one material selected from the group of materials consisting of compounds having chemical formulas (I), (II), (III), and (IV), Li x-y (M1) y ZnCl4···(I) wherein y is a number greater than 0 and less than 1, x is a value such that the chemical formula is charge neutral, and M1 is at least one element selected from the elements of Groups 1, 2, and 13, and is different from Li; Li x Zn 1-z (M2) z Cl4···(II) wherein z is a number greater than 0 and less than 1, x is a value such that chemical formula (II) is charge neutral, M2 is at least one element selected from the elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; Li x ZnCl 4-h (X) h (III) wherein h is greater than 0 and less than 4, x is a value such that chemical formula (III) is charge neutral, and X is at least one element selected from the elements of Groups 16 and 17, and is different from Cl; Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV) In the formula, m is a number of 0 to less than 2, n is a number of 0 to less than 1, o is a number of 0 to less than 4, and x is a value that makes chemical formula (IV) charge neutral, with the proviso that at least two of m, n, and o are not 0; The compounds having chemical formulas (I), (II), (III) and (IV) comprise a crystal lattice structure having an orthorhombic phase of space group Pmn21, However, the content of M1, M2 and / or X is such that the compound maintains its Pmn21 structure.

[0049] The anode may have any anode structure conventionally used in lithium-ion batteries. Generally, such materials are +The anode is capable of adding and extracting ions. Exemplary anode active materials include graphite, hard carbon, lithium titanate (LTO), tin / cobalt alloy, and silicon / carbon composite. In one aspect, the anode can include a current collector and a coating of lithium ion active material disposed on the current collector. Typical current collector materials include, but are not limited to, aluminum, copper, nickel, stainless steel, carbon, carbon paper, and carbon cloth. In aspects advantageously including the solid lithium ion conductivity material described in the first and second embodiments, the anode can be lithium metal or a lithium metal alloy, optionally coated on a current collector. In one aspect, the anode can be a lithium metal sheet that functions as both the active material and the current collector.

[0050] The cathode structure may be any of those conventionally used in lithium-ion batteries, including, but not limited to, composite lithium metal oxides such as lithium cobalt oxide (LiCoO), lithium manganese oxide (LiMnO), lithium iron phosphate (LiFePO), and lithium nickel manganese cobalt oxide. Other active cathode materials may also include elemental sulfur and metal sulfide composites. The cathode may also include a current collector such as copper, aluminum, and stainless steel.

[0051] In one embodiment, the active cathode material may be a transition metal, preferably silver or copper. Such transition metal-based cathodes may not include a current collector.

[0052] In further embodiments, electrodes are also disclosed that include solid electrolyte materials having formulas (I)-(IV). Accordingly, in the fabrication of an electrode, the active material described above may be physically mixed with the solid electrolyte material before being applied to a current collector, or the solid electrolyte material may be applied as a coating layer over the applied active material. In either embodiment, a lithium ion superconductor provided on or within the electrode structure can improve electrode performance and, particularly when applied as a coating layer, can protect conventional solid electrolytes.

[0053] Accordingly, embodiments of the present disclosure include a cathode comprising a current collector and a layer of cathode active material applied to the current collector. The cathode comprises at least one of the following components: i) the cathode active material applied to the current collector is a physical mixture comprising at least one of the solid electrolyte materials having the above-described chemical formulas (I)-(IV), and ii) the layer of cathode active material applied to the current collector is coated with a layer comprising at least one of the solid electrolyte materials having the above-described chemical formulas (I)-(IV). Cathodes comprising both components i) and ii) are also included in the present disclosure.

[0054] In a related embodiment, the present disclosure includes an anode comprising a current collector and a layer of anode active material applied to the current collector, the anode comprising at least one of the following components: i) the anode active material applied to the current collector is a physical mixture comprising at least one of the solid electrolyte materials having formulas (I)-(IV) described above, and ii) the anode active material layer applied to the current collector is coated with a layer comprising at least one of the solid electrolyte materials having formulas (I)-(IV).

[0055] Batteries including a cathode described in any of the above embodiments, an anode described in any of the above embodiments, or both an anode and a cathode described in any of the above embodiments are also embodiments of the present disclosure. [Example]

[0056] Example Using first-principles molecular dynamics simulations, the molecular formula Li 1.5 Zn 0.5 Al 0.5 Cl4 and Li 1.25 Al 0.75 Zn 0.25 The conduction properties of these compounds and their derivatives were determined by studying compounds with Cl4. The initial structure was statically relaxed and set to an initial temperature of 100 K. The structure was then heated to the target temperature (500-650 K) at a constant rate by varying the rate over a 2 ps period. The total time for the AIMD simulation was 400-1000 ps. Li at different temperatures from 500-650 K was measured. + The diffusion rate follows the Arrhenius law.

[0057] Both compounds are doped derivatives of Li2ZnCl4 with an orthorhombic space group Pmn21 crystal lattice structure. Figure 1 shows the crystal structure of Li2ZnCl4. Figure 2 shows the XRD analysis of the crystal structure of Li2ZnCl4, and Figure 3 shows a table listing the peak positions and intensities of peaks with relative intensities greater than or equal to the maximum intensity peak in the XRD analysis of Li2ZnCl4 in Figure 2. Figure 10 shows an Arrhenius plot of the Li-ion diffusivity D as a function of temperature in Li2ZnCl4.

[0058] E at 500 K for Li2ZnCl4, substituted compounds, and LiAlCl4 obtained from AIMD simulations hull (Energy above hull) and Li-ion conductivity are shown in the table below.

[0059] [Table 1]

[0060] Li 1.25 Al 0.75 Zn 0.25 The activation energy of Cl4 is 0.25±0.06 eV, and that of Li 1.25 Al 0.75 Zn 0.25The Li-ion conductivity of Cl4 at 300 K is 14.1 mS / cm with error limits [1.0 mS / cm, 193.3 mS / cm], and E hull is 6 meV per atom. 1.25 Al 0.75 Zn 0.25 The electrochemical window of Cl4 is Li / Li + The voltage range is 1.91 to 4.21V, which is called E hull is the energy difference between a compound and its stable equilibrium phase, and is traditionally used as a descriptor of compound transition and synthesis. hull is 12 meV / atom, lower than 30 meV / atom, suggesting the possibility of experimental synthesis (see A.H. Nolan, Y. Zhu, X. He, Q. Bai, Y. Mo, Joule 2018, 2 2016).

[0061] Figure 4 shows the Li in space group Pmn21. 1.5 Zn 0.5 Al 0.5 Figure 5 shows the crystal structure of LiCl4. 1.5 Zn 0.5 Al 0.5 Figure 6 shows the XRD analysis of the crystal structure of LiCl4 in Figure 5. 1.5 Zn 0.5 Al 0.5 The table below shows the peak positions and intensities of peaks with a relative intensity of 1 or more compared to the maximum intensity peak in the XRD analysis of Cl4.

[0062] Figure 7 shows the Li 1.25 Al 0.75 Zn 0.25 Figure 8 shows the crystal structure of LiCl4 in space group Pmn21. 1.75 Zn 0.75 Al 0.25 Figure 9 shows the XRD analysis of the crystal structure of LiCl4 in Figure 8. 1.25 Al 0.75 Zn 0.25 The table below shows the peak positions and intensities of peaks with a relative intensity of 1 or more compared to the maximum intensity peak in the XRD analysis of Cl4.

[0063] Figures 11, 12 and 13 show the results of AIMD simulations of Li2ZnCl4, Li 1.5 Zn 0.5 Al 0.5 Cl4 and Li 1.25 Al 0.75 Zn 0.25 Figures 11, 12, and 13 show the Li-ion probability density for each of the Al-doped materials and Li2ZnCl4. The Li-ion probability density extracted from AIMD simulations is considered to be the proportion of Li ions at each spatial location within the crystal structure (see He, X., Zhu, Y. & Mo, Y., Nat Commun 8, 15893 (2017)). The Li-ion probability densities in Figures 11, 12, and 13 indicate favorable channels for Li-ion conduction within the crystal structure. The high Li-ion hopping probability of the Al-doped materials and Li2ZnCl4 indicates the favorable lithium-ion conductivity obtained from compounds with chemical formulas (I) through (IV).

[0064] Therefore, these materials with crystalline morphology in the space group Pmn21 have the excellent properties required to function as high Li-ion conducting solid electrolytes, protective coatings for electrodes, or active components of electrodes.

[0065] The above description is presented to enable any person skilled in the art to make and practice the invention and is provided based on a particular application and its requirements. Various modifications to the preferred embodiment will be apparent to those skilled in the art. The generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features disclosed herein. Thus, certain embodiments within the scope of the invention in its broadest form may not represent all of the advantages of the invention.

Claims

1. A solid lithium ion electrolyte, It comprises a compound having the formula (II): <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> ｘ <h2 style=";text-align:left;direction:ltr"> 4Zn<h2 style=";text-align:left;direction:ltr"> １－ｚ <h2 style=";text-align:left;direction:ltr"> (2)<h2 style=";text-align:left;direction:ltr"> ｚ <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> ４ <h2 style=";text-align:left;direction:ltr"> I'm sorry In the formula, z is a number greater than 0 and less than 1, x is a value that makes the chemical formula (II) charge neutral, M2 is at least one element selected from the elements of Groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; The compound having the chemical formula (II) has the space group Pmn2 １ comprising a crystal lattice structure having an orthorhombic phase of However, the content of M2 is the Pmn2 of the compound. １ A solid lithium-ion electrolyte, whose value is such that it maintains its structure.

2. The lithium ions (Li ＋ 2. The solid lithium ion electrolyte of claim 1, wherein the conductivity is 0.1 to 15 mS / cm at 300K.

3. 2. The solid lithium ion electrolyte of claim 1, wherein the activation energy of the material is 0.15 to 0.40 eV.

4. XRD analysis calculated based on Cu-Kα radiation with a wavelength of 1.54184 Å indicates that the space group Pmn2 １ 2. The solid state lithium ion electrolyte of claim 1, comprising the following peaks defining: 【Table 1】

5. 1. A solid-state lithium battery, comprising: an anode; a cathode; a solid-state lithium-ion electrolyte disposed between the anode and the cathode; The solid lithium ion electrolyte comprises a compound having the formula (II): <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> ｘ <h2 style=";text-align:left;direction:ltr"> 4Zn<h2 style=";text-align:left;direction:ltr"> １－ｚ <h2 style=";text-align:left;direction:ltr"> (2)<h2 style=";text-align:left;direction:ltr"> ｚ <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> ４ <h2 style=";text-align:left;direction:ltr"> I'm sorry In the formula, z is a number greater than 0 and less than 1, x is a value that makes the chemical formula (II) charge neutral, M2 is at least one element selected from the elements of Groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; The compound having the chemical formula (II) has the space group Pmn2 １ comprising a crystal lattice structure having an orthorhombic phase of However, the content of M2 is the Pmn2 of the compound. １ A solid-state lithium battery, whose value is such that it maintains its structure.

6. 6. The solid-state lithium battery of claim 5, wherein the solid-state lithium battery is a lithium metal battery or a lithium ion battery.

7. 1. An electrode for a solid-state lithium battery, comprising: A current collector; an electrode active layer provided on the current collector, The electrode active layer comprises a compound having the chemical formula (II): <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> ｘ <h2 style=";text-align:left;direction:ltr"> 4Zn<h2 style=";text-align:left;direction:ltr"> １－ｚ <h2 style=";text-align:left;direction:ltr"> (2)<h2 style=";text-align:left;direction:ltr"> ｚ <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> ４ <h2 style=";text-align:left;direction:ltr"> I'm sorry In the formula, z is a number greater than 0 and less than 1, x is a value that makes the chemical formula (II) charge neutral, M2 is at least one element selected from the elements of Groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; The compound having the chemical formula (II) has the space group Pmn2 １ comprising a crystal lattice structure having an orthorhombic phase of However, the content of M2 is the Pmn2 of the compound. １ The electrode is of such a value that it maintains its structure.

8. 1. An electrode for a solid-state lithium battery, comprising: A current collector; an electrode active layer provided on the current collector; a coating layer provided on the electrode active layer, The coating layer provided on the electrode active layer comprises a compound having chemical formula (II), <h2 style=";text-align:left;direction:ltr">Li<h2 style=";text-align:left;direction:ltr"> ｘ <h2 style=";text-align:left;direction:ltr"> 4Zn<h2 style=";text-align:left;direction:ltr"> １－ｚ <h2 style=";text-align:left;direction:ltr"> (2)<h2 style=";text-align:left;direction:ltr"> ｚ <h2 style=";text-align:left;direction:ltr"> Cl<h2 style=";text-align:left;direction:ltr"> ４ <h2 style=";text-align:left;direction:ltr"> I'm sorry In the formula, z is a number greater than 0 and less than 1, x is a value that makes the chemical formula (II) charge neutral, M2 is at least one element selected from the elements of Groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17, and is different from Zn; The compound having the chemical formula (II) has the space group Pmn2 １ comprising a crystal lattice structure having an orthorhombic phase of However, the content of M2 is the Pmn2 of the compound. １ The electrode is of such a value that it maintains its structure.

9. A solid-state lithium battery comprising the electrode of claim 7, The solid-state lithium battery is a lithium-ion battery or a lithium metal battery.

10. A solid-state lithium battery comprising the electrode of claim 8, The solid-state lithium battery is a lithium-ion battery or a lithium metal battery.

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