LiZnCl4 derivatives in space group Pmn21 used as lithium superionic conductors, solid electrolytes, and coatings in lithium metal and lithium-ion batteries

Abstract

This invention provides a solid-state lithium-ion electrolyte of a lithium zinc chloride derivative compound having a crystal morphology in the Pmn21 space group as a material for conducting lithium ions. The activation energy of the lithium aluminum chloride derivative compound is 0.15 to 0.40 eV, and the conductivity is 0.01 to 15 mS / cm at 300 K. This invention provides a compound of a specific formula and a method for modifying the material by including the indicated heterovalent ions. This invention also provides a lithium battery containing a composite lithium-ion electrolyte and an electrode containing a lithium aluminum chloride derivative compound.

Description

[0001] Names of the parties to the joint research agreement

[0002] The contents of this paper are the result of a joint research effort conducted under a joint research agreement between Toyota Motor Engineering & Manufacturing North America, Inc. (6565 Headquarters Drive W1-3C, Plano, Texas, 75024) and the University of Maryland, College Park (2130 Mitchell Bldg. 7999 Regents Dr. Colledge Park, Maryland, 20742). Technical Field

[0003] This disclosure relates to novel LiZnCl4 derivative compounds with high lithium-ion conductivity having a crystal structure of the Pmn21 space group, which can be used as solid electrolytes and electrode components and / or electrode coatings for lithium-ion and lithium metal batteries. Background Technology

[0004] Lithium-ion batteries have traditionally dominated the market for portable electronic devices. However, conventional lithium-ion batteries contain flammable organic solvents as components of the electrolyte, and this flammability is the basis of a safety risk that is of concern and may limit or prevent the use of lithium-ion batteries for large-scale energy storage.

[0005] Replacing the flammable organic liquid electrolyte with a solid Li conductive phase would alleviate this safety concern and could offer additional advantages such as improved mechanical and thermal stability. The primary function of the solid Li conductive phase (often referred to as a solid Li ion conductor or solid electrolyte) is to conduct Li ions during discharge. + Ions are conducted from the anode side to the cathode side and from the cathode side to the anode side during charging, while blocking the direct transport of electrons between the electrodes within the battery.

[0006] Furthermore, it is known that lithium batteries constructed with non-aqueous electrolytes form dendritic lithium metal structures protruding from the anode to the cathode during repeated discharge and charge cycles. If, and when such dendritic structures protrude to the cathode and short-circuit, battery energy is rapidly released and can ignite the organic solvent.

[0007] Therefore, researchers have been focusing on and dedicated to discovering new solid-state Li ion-conducting materials that will enable all-solid-state lithium batteries. Research over the past few decades has primarily concentrated on ion-conducting oxides, such as LISICON (Li 14 ZnGe4O 16 ), NASICON (Li 1.3 Al 0.3 Ti 1.7 (PO4)3), perovskite (e.g., La)0.5 Li 0.5 TiO3), garnet (Li7La3Zr2O) 12 ), LiPON (e.g., Li 2.88 PO 3.73 N 0.14 ) and sulfides such as Li3PS4, Li7P3S 11 and LGPS (Li 10 GeP2S 12 ).

[0008] Although recent developments have rated the conductivity of solid lithium-ion conductors at the level of 1-10 mS / cm, which is comparable to that in liquid electrolytes, the search for new solid lithium-ion conductors remains of great interest.

[0009] An effective lithium-ion solid conductor will have high Li-level performance at room temperature. + Conductivity. Typically, Li... + The conductivity should be no less than 10. -6 S / cm. Furthermore, Li in the conductor + The activation energy for migration must be low to allow for use within the range of operating temperatures likely encountered in the environment. Furthermore, the material should exhibit good stability against chemical, electrochemical, and thermal degradation. Unlike many conventionally used non-aqueous solvents, solid-state conductor materials should be stable against electrochemical degradation reactivity of both anodic and cathodic chemical compositions. The material should possess low grain boundary resistance for use in all-solid-state batteries. Ideally, the synthesis of this material should be easy and inexpensive.

[0010] The standard redox potential of Li / Li+ is -3.04 V, making lithium metal one of the strongest available reducing agents. Therefore, Li metal can reduce most known cation species to lower oxidation states. Due to this strong reducing ability, when lithium metal at the anode contacts solid Li containing a cation composition different from lithium ions... + When lithium is used as a conductor, it reduces the cations to a lower oxidation state and degrades the solid conductor.

[0011] Therefore, many currently known solid Li ion conductors suffer from stability problems when in contact with Li metal anodes.

[0012] The inventors of this application have studied lithium compounds that can be used as solid Li+ conductors in the future, and previous results of this study have been disclosed in U.S. Application No. 15 / 626696, filed June 19, 2017; U.S. Application No. 15 / 805672, filed November 7, 2017; U.S. Application No. 16 / 013495, filed June 20, 2018; U.S. Application No. 16 / 114946, filed August 28, 2018; and U.S. Application No. 16 / 14, filed September 26, 2018. U.S. Application No. 2217, U.S. Application No. 16 / 144157 (filed September 27, 2018), U.S. Application No. 16 / 153335 (filed October 10, 2018), U.S. Application No. 16 / 155349 (filed October 9, 2018), U.S. Application No. 16 / 264294 (filed January 31, 2019), U.S. Application No. 16 / 570811 (filed September 13, 2019), and U.S. Application No. 16 / 570888 (filed September 13, 2019). However, research continues to uncover additional materials with maximum efficiency, high stability, low cost, and ease of handling and fabrication.

[0013] Therefore, the purpose of this application is to identify a range of other materials that have high Li-ion conductivity and are poor electronic conductors, which are suitable as solid electrolyte and / or electrode components for lithium-ion and lithium metal batteries.

[0014] Another objective of this application is to provide solid-state lithium-ion and / or lithium metal batteries containing these materials which have high Li-ion conductivity and are poor electronic conductors. Summary of the Invention

[0015] These and other objectives are provided through embodiments of this application, the first of which includes a solid lithium-ion electrolyte comprising at least one material selected from the group consisting of compounds of formulas (I), (II), (III), and (IV):

[0016] Li x-y (M1) y ZnCl4 (I)

[0017] in

[0018] y is a number greater than 0 and less than 2, x is a value that makes the expression charge neutral, and M1 is at least one element different from Li selected from elements of groups 1, 2 and 13.

[0019] Li x Zn 1-z (M2) z Cl4 (II)

[0020] in

[0021] z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is at least one element different from Zn selected from elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17.

[0022] Li x ZnCl 4-h (X) h (III)

[0023] in

[0024] h is greater than 0 and less than 4, x is a value that makes equation (III) charge neutral, and X is at least one element selected from groups 16 and 17 other than Cl; and

[0025] Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV)

[0026] in

[0027] m is a number from 0 to less than 2, n is a number from 0 to less than 1, o is a number from 0 to less than 4, and x is a value that makes equation (IV) charge-neutral, provided that at least two of m, n, and o cannot be 0.

[0028] The compounds of formulas (I), (II), (III), and (IV) contain an orthorhombic lattice structure with space group Pmn21, and

[0029] The condition is that the contents of M1, M2 and / or X are values ​​that allow the Pmn21 structure of the compound to be maintained.

[0030] In one aspect of the first embodiment, the lithium-ion (Li) of the solid lithium-ion electrolyte of formulas (I) to (IV) + The conductivity is 0.1 to 15 mS / cm at 300 K.

[0031] In another aspect of the first embodiment, the activation energy of the complexes of formulas (I) to (IV) is 0.15 to 0.40 eV.

[0032] In a second embodiment, a solid-state lithium battery is provided. The battery includes:

[0033] anode;

[0034] cathode; and

[0035] A solid lithium-ion electrolyte is located between the anode and the cathode.

[0036] The solid lithium-ion electrolyte comprises at least one material selected from the group consisting of compounds of formulas (I), (II), (III), and (IV):

[0037] Li x-y (M1) y ZnCl4 (I)

[0038] in

[0039] y is a number greater than 0 and less than 2, x is a value that makes the expression charge neutral, and M1 is at least one element different from Li selected from elements of groups 1, 2 and 13.

[0040] Li x Zn 1-z (M2) z Cl4 (II)

[0041] in

[0042] z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is at least one element different from Zn selected from elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17.

[0043] Li x ZnCl 4-h (X) h (III)

[0044] in

[0045] h is greater than 0 and less than 4, x is a value that makes equation (III) charge neutral, and X is at least one element selected from groups 16 and 17 other than Cl; and

[0046] Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV)

[0047] in

[0048] m is a number from 0 to less than 2, n is a number from 0 to less than 1, o is a number from 0 to less than 4, and x is a value that makes equation (IV) charge-neutral, provided that at least two of m, n, and o cannot be 0.

[0049] The compounds of formulas (I), (II), (III), and (IV) contain an orthorhombic lattice structure with space group Pmn21, and

[0050] The condition is that the contents of M1, M2 and / or X are values ​​that allow the Pmn21 structure of the compound to be maintained.

[0051] The lithium battery in the second embodiment can be a lithium metal battery or a lithium-ion battery.

[0052] In a third embodiment, an electrode for a solid-state lithium battery is provided. The electrode comprises:

[0053] Current collector; and

[0054] The electrode active layer on the current collector

[0055] The electrode active layer comprises at least one compound selected from the group consisting of compounds of formulas (I), (II), (III), and (IV):

[0056] Li x-y (M1) y ZnCl4 (I)

[0057] in

[0058] y is a number greater than 0 and less than 2, x is a value that makes the expression charge neutral, and M1 is at least one element different from Li selected from elements of groups 1, 2 and 13.

[0059] Li x Zn 1-z (M2) z Cl4 (II)

[0060] in

[0061] z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is at least one element different from Zn selected from elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17.

[0062] Li x ZnCl 4-h (X) h (III)

[0063] in

[0064] h is greater than 0 and less than 4, x is a value that makes equation (III) charge neutral, and X is at least one element selected from groups 16 and 17 other than Cl; and

[0065] Lix-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV)

[0066] in

[0067] m is a number from 0 to less than 2, n is a number from 0 to less than 1, o is a number from 0 to less than 4, and x is a value that makes equation (IV) charge-neutral, provided that at least two of m, n, and o cannot be 0.

[0068] The compounds of formulas (I), (II), (III), and (IV) contain an orthorhombic lattice structure with space group Pmn21, and

[0069] The condition is that the contents of M1, M2 and / or X are values ​​that allow the Pmn21 structure of the compound to be maintained.

[0070] In a fourth embodiment, an electrode for a solid-state lithium battery is provided. The electrode comprises:

[0071] current collector;

[0072] The electrode active layer on the current collector; and

[0073] The coating on the electrode active layer

[0074] The coating on the electrode active layer comprises at least one compound selected from the group consisting of compounds of formulas (I), (II), (III), and (IV):

[0075] Li x-y (M1) y ZnCl4 (I)

[0076] in

[0077] y is a number greater than 0 and less than 2, x is a value that makes the expression charge neutral, and M1 is at least one element different from Li selected from elements of groups 1, 2 and 13.

[0078] Li x Zn 1-z (M2) z Cl4 (II)

[0079] in

[0080] z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is at least one element different from Zn selected from elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17.

[0081] Li x ZnCl 4-h (X) h (III)

[0082] in

[0083] h is greater than 0 and less than 4, x is a value that makes equation (III) charge neutral, and X is at least one element selected from groups 16 and 17 other than Cl; and

[0084] Li x-m (M1) m Al 1-n (M2) n Cl 4-o (X) o (IV)

[0085] in

[0086] m is a number from 0 to less than 2, n is a number from 0 to less than 1, o is a number from 0 to less than 4, and x is a value that makes equation (IV) charge-neutral, provided that at least two of m, n, and o cannot be 0.

[0087] The compounds of formulas (I), (II), (III), and (IV) contain an orthorhombic lattice structure with space group Pmn21, and

[0088] The condition is that the contents of M1, M2 and / or X are values ​​that allow the Pmn21 structure of the compound to be maintained.

[0089] Solid-state lithium batteries are also provided, which include electrodes and / or electrolytes with various implementations and aspects thereof. Solid-state lithium batteries can be lithium metal batteries or lithium-ion batteries.

[0090] The foregoing description is intended to provide a general introduction and overview of this disclosure and is not intended to limit this disclosure, unless otherwise expressly stated. The presently preferred embodiments and further advantages will be best understood by referring to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0091] This patent or application document contains at least one color drawing. Copies of this patent or patent application disclosure containing one or more color drawings will be provided by the Patent Office upon request and payment of the necessary fees.

[0092] Figure 1 The crystal structure of Li2ZnCl4 in space group Pmn21 is shown.

[0093] Figure 2 XRD analysis of the crystal structure of Li2ZnCl4 in space group Pmn21 is shown.

[0094] Figure 3 Showing the list with Figure 2 Table showing the peak position and intensity of the maximum intensity peak compared to peaks with a relative intensity of 1 or greater in XRD analysis of Li₂ZnCl₄.

[0095] Figure 4 Li shows the Pmn21 space group 1.5 Zn 0.5 Al 0.5 Crystal structure of Cl4.

[0096] Figure 5 Li shows the Pmn21 space group 1.5 Zn 0.5 Al 0.5 XRD analysis of the crystal structure of Cl4.

[0097] Figure 6 Showing the list with Figure 5 Zhong Li 1.5 Zn 0.5 Al 0.5 Table of peak positions and intensities in XRD analysis of Cl4, relative to peaks with a relative intensity of 1 or greater.

[0098] Figure 7 Li shows the Pmn21 space group 1.25 Al 0.75 Zn 0.25 Crystal structure of Cl4.

[0099] Figure 8 Li shows the Pmn21 space group 1.25 Al 0.75 Zn 0.25 XRD analysis of the crystal structure of Cl4.

[0100] Figure 9 Showing the list with Figure 8 Zhong Li 1.75 Al 0.75 Zn 0.25 Table of peak positions and intensities in XRD analysis of Cl4, relative to peaks with a relative intensity of 1 or greater.

[0101] Figure 10 The Arrhenius plot of the lithium-ion diffusion rate D in Li2ZnCl4 obtained from AIMD simulation is shown.

[0102] Figure 11 The probability density of lithium ions in Li2ZnCl4 is shown from AIMD simulations.

[0103] Figure 12 The Li obtained from AIMD simulation is shown. 1.5 Zn 0.5 Al 0.5 Lithium ion probability density in Cl4.

[0104] Figure 13 The Li obtained from AIMD simulation is shown. 1.25 Al 0.75 Zn 0.25 Lithium ion probability density in Cl4. Detailed Implementation

[0105] Throughout this specification, the terms "electrochemical cell" and "cell" may be used interchangeably unless the context clearly distinguishes an electrochemical cell from a cell. Furthermore, the terms "solid electrolyte" and "solid ionic conductor" may be used interchangeably unless otherwise explicitly stated.

[0106] Regarding the known Li + ionic conductor Li 10 GeP2S 12 and Li7P3S 11 Ceder et al. (Nature Materials, 14, 2015, 1026-1031) have described efficient Li + The structural properties of the conductive lattice are shown, revealing a very close match between the thiodilatant lattices of the two materials and the bcc lattice structure. Additionally, it indicates Li coordination across adjacent tetrahedra. + Li at lattice sites + Ion hopping provides the pathway with the lowest activation energy.

[0107] The inventors are conducting ongoing research on novel lithium composite compounds to identify materials with properties suitable for use as solid electrolytes in solid-state lithium batteries. In the course of this ongoing research, the inventors have developed and implemented methods for identifying composite materials with chemical and structural properties that have been determined by the inventors as indicators of lithium-ion conductivity suitable for use as solid electrolytes in lithium-ion batteries and as components of electrodes adjacent to the solid electrolyte.

[0108] To qualify as a solid-state electrolyte in practical applications, the material must meet several specific criteria. First, it should exhibit the desired lithium-ion conductivity, typically not less than 10 at room temperature. -6S / cm. Second, the material should exhibit good stability against chemical, electrochemical, and thermal degradation. Third, the material should have low grain boundary resistance for use in all-solid-state batteries. Fourth, the material should be easy to synthesize and not expensive.

[0109] The standard requirement for this method is that, in order to qualify as a solid-state electrolyte in practical applications, the material must exhibit the desired lithium-ion conductivity at room temperature, typically not less than 10. -6 S / cm. Therefore, ab initio molecular dynamics simulations were applied to calculate the diffusion rate of lithium ions in the lattice structure of the selected silicate material. To accelerate the simulation, calculations were performed at high temperatures, and the effects of excess Li or Li vacancies were considered. To generate excess Li or Li vacancies, heterovalent substitution of cations or anions can be evaluated. Therefore, Li vacancies are generated, for example, by partially substituting Si with heterovalent cations while compensating for charge neutrality with Li vacancies or excess Li. For example, substituting Li with P. 10 Si2PbO 10 50% of the Si in the solution leads to the formation of Li9PSiPbO 10 .

[0110] According to equation (I), the diffusivity at 300K is determined.

[0111] D = D0exp(-E a / k b Equation (I)

[0112] Among them, D0, E a and k b These refer to the prefactor, activation energy, and Boltzmann constant, respectively. According to equation (II), the conductivity is related to the calculated diffusivity:

[0113] σ=D 300 ρe 2 / k b Equation (II)

[0114] Where ρ is the volume density of lithium ions and e is the unit charge.

[0115] The anionic lattice of Li-ion conductors has been shown to match several lattice types (see Nature Materials, 14, 2015, 2016). Therefore, potential Li-ion conductors... + The anionic lattice of ionic conductors and Li, which is known to have high conductivity + Comparison of anionic lattices of ionic conductors.

[0116] Therefore, the selected lithium aluminum chloride derivative compounds were compared with Li-containing compounds reported in the Inorganic Crystal Structure Database (FIZKarlsruhe ICSD - https: / / icsd.fiz-karlsruhe.de) and evaluated using an anion lattice matching method developed by the inventors for this purpose and described in co-pending U.S. Application No. 15 / 597651, filed May 17, 2017, to match the lattices of these compounds with known lithium-ion conductors.

[0117] According to the anion lattice matching method described in co-pending U.S. Application No. 15 / 597651, the atomic coordinate system of a compound lattice structure can be converted to a coordinate system used only for anion lattices. The anions in the lattice are replaced with anions from the comparison material, and the resulting unit cell is rescaled. X-ray diffraction data for the modified anion-only lattice can be simulated, and an n×2 matrix is ​​generated from the simulated diffraction data. Quantitative structural similarity values ​​can be derived from the n×2 matrix.

[0118] The purpose of anion lattice matching is to further identify those with the maximum potential to exhibit high Li content. + Compounds with high conductivity. From this work, compounds described in subsequent embodiments were identified as potentially suitable as solid-state Li. + conductor.

[0119] Then, ab initio molecular dynamics (AIMD) simulations were applied to predict the conductivity of the target lithium aluminum chloride derivative compound. 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 using a rate scale over a time interval of 2 ps. The total AIMD simulation time ranged from 400 to 1000 ps. A typical example of the calculated diffusivity versus temperature is shown below. Figure 11 As shown. Li at different temperatures from 500-650 K. + The diffusion rate follows an Arrhenius-type relationship.

[0120] Apply equation (I) to determine the diffusivity at 300 K, and then use the relationship between conductivity and diffusivity in equation (II) to determine the conductivity.

[0121] Therefore, the first embodiment provides a solid lithium-ion electrolyte comprising at least one material selected from the group consisting of compounds of formulas (I), (II), (III), and (IV):

[0122] Li x-y (M1) y ZnCl4 (I)

[0123] in

[0124] y is a number greater than 0 and less than 1, x is a value that makes the expression charge neutral, and M1 is at least one element different from Li selected from elements of groups 1, 2 and 13.

[0125] Li x Zn 1-z (M2) z Cl4 (II)

[0126] in

[0127] z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is at least one element different from Zn selected from elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17.

[0128] Li x ZnCl 4-h (X) h (III)

[0129] in

[0130] h is greater than 0 and less than 4, x is a value that makes equation (III) charge neutral, and X is at least one element selected from groups 16 and 17 other than Cl; and

[0131] Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV)

[0132] in

[0133] m is a number from 0 to less than 1, n is a number from 0 to less than 1, o is a number from 0 to less than 4, and x is a value that makes equation (IV) charge-neutral, provided that at least two of m, n, and o cannot be 0.

[0134] The compounds of formulas (I), (II), (III), and (IV) contain an orthorhombic lattice structure with space group Pmn21, and

[0135] The condition is that the contents of M1, M2 and / or X are values ​​that allow the Pmn21 structure of the compound to be maintained.

[0136] The compounds of formulas (I)-(IV) are derivatives of Li₂ZnCl₄ with an orthorhombic lattice structure of space group Pmn₂₁. Figure 1The lattice structure of Li₂ZnCl₄ in space group Pmn₂₁ is depicted, and... Figure 2 The figure shows the wavelength-based [value] for this space group. The calculated X-ray diffraction (XRD) pattern of Cu-Kα radiation. Peak positions and relative intensities are shown in... Figure 3 middle.

[0137] The inventors have determined that replacing Li with element M1, Zn with M2, and Cl with X in Li2ZnCl4 of space group Pmn21 can enhance Li ion mobility and increase Li ion density in the lattice, thereby providing an effective Li ion conductor that can be used as a solid electrolyte in lithium batteries.

[0138] The extent to which doping or substitution can be performed in Li₂ZnCl₄ while preserving the Pmn₂₁ morphology varies depending on the element used as the dopant. Generally, the more similar the ionic radius and electronic structure, the greater the molar amount of dopant that can be used without significant alteration of the crystal morphology. The simulation methods applied and described in this paper can be used to determine the extent to which doping with a given element can be performed without changing the basic Pmn₂₁ crystal structure.

[0139] For example, as described in the embodiments, Al 3+ Zn can be doped 2+ The ratio was increased to 0.75Al / 0.25Zn while retaining the Pmn21 structure.

[0140] In other aspects of the first embodiment, simulation studies have determined that the solid electrolytes of formulas (I) to (IV) can have lithium ion (Li) concentrations of 0.01 to 10 mS / cm, preferably 0.1 to 15 mS / cm, at 300 K. + Conductivity.

[0141] Furthermore, the activation energies of the solid electrolytes of formulas (I) to (IV) can be from 0.15 to 0.40 eV.

[0142] The synthesis of the composite materials described in the above embodiments can be achieved through a solid-state reaction between stoichiometric amounts of selected precursor materials. Exemplary methods of solid-state synthesis are described, for example, in each of the following documents: i) Monatshefte für Chemie, 100, 295-303, 1969; ii) Journal of Solid State Chemistry, 128, 1997, 241; iii) Zeitschrift für 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.

[0143] In a further embodiment, this application includes a solid-state lithium-ion battery containing the aforementioned solid-state electrolyte. These embodiments of solid-state batteries, including metal-metal solid-state batteries, can have higher charge / discharge rate performance and higher power density than conventional batteries, and have the potential to provide high power and energy density.

[0144] Therefore, in a further embodiment, a solid-state lithium battery is provided. The solid-state lithium battery comprises: an anode; a cathode; and a solid-state lithium-ion electrolyte located between the anode and the cathode; wherein the solid-state lithium-ion electrolyte comprises at least one material selected from the group consisting of compounds of formulas (I), (II), (III), and (IV).

[0145] Li x-y (M1) y ZnCl4 (I)

[0146] in

[0147] y is a number greater than 0 and less than 1, x is a value that makes the expression charge neutral, and M1 is at least one element different from Li selected from elements of groups 1, 2 and 13.

[0148] Li x Zn 1-z (M2) z Cl4 (II)

[0149] in

[0150] z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is at least one element different from Zn selected from elements of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16 and 17.

[0151] Li x ZnCl 4-h (X) h (III)

[0152] in

[0153] h is greater than 0 and less than 4, x is a value that makes equation (III) charge neutral, and X is at least one element selected from groups 16 and 17 other than Cl; and

[0154] Li x-m (M1) m Zn 1-n (M2) n Cl 4-o (X) o (IV)

[0155] in

[0156] m is a number from 0 to less than 1, n is a number from 0 to less than 1, o is a number from 0 to less than 4, and x is a value that makes equation (IV) charge-neutral, provided that at least two of m, n, and o cannot be 0.

[0157] The compounds of formulas (I), (II), (III), and (IV) contain an orthorhombic lattice structure with space group Pmn21, and

[0158] The condition is that the contents of M1, M2 and / or X are values ​​that allow the Pmn21 structure of the compound to be maintained.

[0159] The anode can be any anode structure conventionally used in lithium-ion batteries. Typically, such materials are capable of inserting and extracting Li... + Ions. Example anode active materials may include graphite, hard carbon, lithium titanate (LTO), tin / cobalt alloys, and silicon / carbon composites. In one aspect, the anode may include a current collector and a coating of lithium-ion active material on the current collector. Standard current collector materials include, but are not limited to, aluminum, copper, nickel, stainless steel, carbon, carbon paper, and carbon cloth. In aspects where the solid-state lithium-ion conducting material described in the first and second embodiments is advantageously configured, the anode may be lithium metal or a lithium metal alloy, optionally coated on the current collector. In one aspect, the anode may be a sheet of lithium metal that serves as both an active material and a current collector.

[0160] The cathode structure can be any structure conventionally used in lithium-ion batteries, including but not limited to composite lithium metal oxides such as lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), and lithium nickel manganese cobalt oxide. Other active cathode materials may also include elemental sulfur and metal sulfide composites. The cathode may also include current collectors such as copper, aluminum, and stainless steel.

[0161] In one aspect, the active cathode material can be a transition metal, preferably silver or copper. A cathode based on this transition metal may not contain a current collector.

[0162] In another set of embodiments, electrodes containing solid electrolyte materials of formulas (I)-(IV) are also disclosed. Therefore, in the preparation of the electrode, the active material as described above can be physically mixed with the solid electrolyte material before being applied to the current collector, or the solid electrolyte material can be applied as a coating onto the applied active material. In any embodiment, the presence of a lithium-ion superconductor in or within the electrode structure can enhance the electrode's performance, and, particularly when applied as a coating, can be used to protect conventional solid electrolytes.

[0163] Therefore, embodiments of this disclosure include a cathode comprising a current collector and a cathode active material layer applied to the current collector, wherein at least one of the following components is present: i) the cathode active material applied to the current collector is a physical mixture containing at least one of the solid electrolyte materials of formulas (I)-(IV) as described above; and ii) the cathode active material layer applied to the current collector is coated with a layer containing at least one of the solid electrolyte materials of formulas (I)-(IV). This disclosure also includes a cathode having both elements i) and ii).

[0164] In related embodiments, this disclosure includes an anode comprising a current collector and an anode active material layer applied to the current collector, wherein at least one of the following components is present: i) the anode active material applied to the current collector is a physical mixture containing at least one of the solid electrolyte materials of formulas (I)-(IV) as described above; and ii) the anode active material layer applied to the current collector is coated with a layer containing at least one of the solid electrolyte materials of formulas (I)-(IV).

[0165] A battery containing the cathode described in the above embodiments, the anode described in the above embodiments, or both the anode and cathode according to the above embodiments is also an embodiment of this disclosure.

[0166] Example

[0167] The Li equation was studied using ab initio dynamic simulation. 1.5 Zn 0.5 Al0.5 Cl4 and Li 1.25 Al 0.75 Zn 0.25 Compounds of Cl4 were used to determine the conductivity properties of these compounds and their derivatives. 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 using a rate scale over a time interval of 2 ps. The total AIMD simulation time ranged from 400 to 1000 ps. Li4 was studied at different temperatures from 500-650 K. + The diffusion rate follows an Arrhenius-type relationship.

[0168] Both compounds are doped derivatives of Li₂ZnCl₄ with an orthorhombic space group Pmn₂₁ lattice structure. The crystal structure of Li₂ZnCl₄ is shown in [image / description]. Figure 1 . Figure 2 XRD analysis showing the crystal structure of Li₂ZnCl₄ is presented, and Figure 3 Showing the list with Figure 2 Table showing the peak position and intensity of the maximum intensity peak compared to peaks with a relative intensity of 1 or greater in XRD analysis of Li₂ZnCl₄. Figure 10 The Arrhenius plot of the Li ion diffusion rate D versus temperature is shown for Li₂ZnCl₄.

[0169] The Li ion conductivity at 500 K and Et of Li2ZnCl4, substituted compounds, and LiAlCl4 from AIMD simulations were compared with those of Et. hull (Energy above the hull) is shown in the table below.

[0170] composition <![CDATA[E hull (meV / atom)]]> σ(mS / cm)(500K) <![CDATA[Li2ZnCl4]]> 12 39 <![CDATA[Li 1.5 Al 0.5 Zn 0.5 Cl4]]> 13 280 <![CDATA[Li 1.25 Al 0.75 Zn 0.25 Cl4]]> 6 198 <![CDATA[LiAlCl4]]> 0 ＜30

[0171] 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 0.25 The Li ion conductivity of Cl4 at 300 K is 14.1 mS cm⁻¹. -1 It has an error limit of [1.0 mS cm]. -1 193.3mS cm -1 ], E hull It is 6 meV per atom, and Li 1.25 Al 0.75 Zn 0.25 The electrochemical window of Cl4 relative to Li / Li + The voltage ranges from 1.91 to 4.21 V. E hullEquation is the energy difference between a compound and its stable phase equilibrium, and it is often used as a descriptor to demonstrate the metastable state and synthesizability of a compound. The Equation for Li₂ZnCl₄ is an example. hull (12 meV / atom) is less than 30 meV / atom, which suggests the syntheticity of the experiment (see AHNolan, Y. Zhu, X. He, Q. Bai, Y. Mo, Joule 2018, 22016).

[0172] Figure 4 The Li in the Pmn21 space group is shown 1.5 Zn 0.5 Al 0.5 Crystal structure of Cl4. Figure 5 Li is shown 1.5 Zn 0.5 Al 0.5 XRD analysis of the crystal structure of Cl4, and Figure 6 Showing the list with Figure 5 Li 1.5 Zn 0.5 Al 0.5 Table of peak positions and intensities in XRD analysis of Cl4, relative to peaks with a relative intensity of 1 or greater.

[0173] Figure 7 Li is shown 1.25 Al 0.75 Zn 0.25 Crystal structure of Cl4. Figure 8 The Li in the Pmn21 space group is shown 1.75 Zn 0.75 Al 0.25 XRD analysis of the crystal structure of Cl4, and Figure 9 Showing the list with Figure 8 Li 1.25 Al 0.75 Zn 0.25 Table of peak positions and intensities in XRD analysis of Cl4, relative to peaks with a relative intensity of 1 or greater.

[0174] Figure 11 , 12 Figures 1 and 13 show the Li₂ZnCl₄ and Li₂ obtained from AIMD simulations, respectively. 1.5 Zn 0.5 Al 0.5 Cl4 and Li 1.25 Al 0.75 Zn 0.25Li ion probability density in Cl4. The lithium ion probability density extracted from AIMD simulations counts the fraction of Li ions at each spatial location in the crystal structure (see He.X, Zhu, Y. and Mo, Y. Nat Commun 8, 15893 (2017)). Figure 11 , 12 The lithium-ion probability density in equations (I) and (IV) shows a good channel for Li-ion conduction in the crystal structure. The high probability of Li-ion hopping in Al-doped materials and Li₂ZnCl₄ demonstrates the favorable lithium-ion conductivity obtained with compounds of formulas (I)-(IV).

[0175] Therefore, these materials with the crystal morphology of the Pmn21 space group possess the excellent properties necessary for use as high lithium-ion conductive solid electrolytes, protective coatings for electrodes, or active components of electrodes.

[0176] The above description is provided to enable those skilled in the art to implement and use the invention, and is offered in the context of specific applications and their requirements. Various modifications to the preferred embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the invention. Therefore, the invention is not limited to the embodiments shown, but should be given the widest scope consistent with the principles and features disclosed herein. In this regard, it is to be considered broadly that some embodiments within the invention may not demonstrate every benefit of the invention.

Claims

1. A solid lithium-ion electrolyte comprising: at least one material selected from the group consisting of compounds of formula (II): Li x Zn 1-z (M2) z Cl4(II) in z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is Al; The compound of formula (II) comprises a lattice structure of an orthorhombic phase having space group Pmn21, and The condition is that the content of M2 is such that the Pmn21 structure of the compound is maintained.

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

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

4. The solid-state lithium-ion electrolyte according to claim 1, wherein, The XRD analysis calculated based on Cu-Kα radiation at a wavelength of 1.54184 Å includes the following peaks, which define the Pmn21 space group: 。 5. Solid-state lithium battery, including: anode; cathode; and A solid lithium-ion electrolyte is located between the anode and the cathode. in, The solid lithium-ion electrolyte comprises at least one material selected from the group consisting of compounds of formula (II): Li x Zn 1-z (M2) z Cl4(II) in z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is Al; The compound of formula (II) comprises a lattice structure of an orthorhombic phase having space group Pmn21, and The condition is that the content of M2 is such that the Pmn21 structure of the compound is maintained.

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

7. Electrodes for solid-state lithium batteries, comprising: Current collector; and The electrode active layer on the current collector The electrode active layer comprises at least one compound selected from the group consisting of compounds of formula (II): Li x Zn 1-z (M2) z Cl4(II) in z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is Al; The compound of formula (II) comprises a lattice structure of an orthorhombic phase having space group Pmn21, and The condition is that the content of M2 is such that the Pmn21 structure of the compound is maintained.

8. Electrodes for solid-state lithium batteries, comprising: current collector; The electrode active layer on the current collector; and The coating on the electrode active layer The coating on the electrode active layer comprises at least one compound selected from the group consisting of compounds of formula (II): Li x Zn 1-z (M2) z Cl4(II) in z is a number greater than 0 and less than 1, x is a value that makes equation (II) charge neutral, and M2 is Al; The compound of formula (II) comprises a lattice structure of an orthorhombic phase having space group Pmn21, and The condition is that the content of M2 is such that the Pmn21 structure of the compound is maintained.

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

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

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