Silicate compounds as solid Li-ion conductors

Abstract

Solid-state lithium ion electrolytes of lithium silicate based composites are provided which contain an anionic framework capable of conducting lithium ions. An activation energy for lithium ion migration in the solid state lithium ion electrolytes is 0.5 eV or less and room temperature conductivities are greater than 10.sup.0.5 S/cm. Composites of specific formulae are provided and methods to alter the composite materials with inclusion of aliovalent ions shown. Lithium batteries containing the composite lithium ion electrolytes are also provided.

Claims

1. A solid-state lithium ion electrolyte, comprising: a composite material of formula (I):
Li.sub.y(M1).sub.x1Si.sub.2-x2(M2).sub.x2O.sub.7  (I) wherein x1 is a number from greater than 0 to less than 6, x2 is a number from greater than 0 to less than 2, y is a value such that the composite of formula (I) is charge neutral, M1 is at least one element selected from the group of elements consisting of a group 1 element, a group 2 element and a group 12 element, and M2 is at least one element selected from the group of elements consisting of a group 13 element, a group 14 element, and a group 15 element.

2. The solid state lithium ion electrolyte according to claim 1, wherein a lithium ion (Li.sup.+) conductivity of the solid state lithium ion electrolyte is at least 10.sup.−5 S/cm at 300K.

3. The solid state lithium ion electrolyte according to claim 1, wherein an activation energy of the composite of formula (I) is 0.4 eV or less.

4. The solid state lithium ion electrolyte according to claim 1, wherein the composite of formula (I) comprises a crystal lattice structure having a tetragonal unit cell.

5. The solid state lithium ion electrolyte according to claim 1, wherein an XRD analysis of the composite comprises the following major peaks: TABLE-US-00007 Peak Position Relative Intensity 21.55 24.8 24.47 52.16 25.82 100 31.76 21.87 36.84 31.47 41.38 19.87 47.12 25.34.

6. A solid-state lithium ion electrolyte, comprising: a composite material of formula (II):
Li.sub.y(M1).sub.x1Si.sub.2-x2d(M2).sub.x2Pb.sub.1-x3(M3).sub.x3O.sub.7  (II) wherein x1 is a number from greater than 0 to less than 10, x2 is a number from greater than 0 to less than 2, x3 is a number from greater than 0 to less than 1, and y is a value such that the composite of formula (II) is charge neutral, M1 is at least one element selected from the group of elements consisting of a group 1 element, a group 2 element and a group 12 element, M2 is at least one element selected from the group of elements consisting of a group 13 element, a group 14 element, and a group 15 element, M3 is at least one element selected from a group 2 element, a group 12 element, a group 13 element, a group 14 element and a group 15 element.

7. The solid state lithium ion electrolyte according to claim 6, wherein a lithium ion (Li.sup.+) conductivity of the solid state lithium ion electrolyte is at least 10.sup.−5 S/cm at 300K.

8. The solid state lithium ion electrolyte according to claim 6, wherein an activation energy of the composite of formula (II) is 0.45 eV or less.

9. The solid state lithium ion electrolyte according to claim 6, wherein the composite of formula (II) comprises a crystal lattice structure having a monoclinic unit cell.

10. A solid state lithium ion electrolyte, comprising: a composite material of formula (IIa):
Li.sub.10Si.sub.2PbO.sub.10  (IIa).

11. The solid state lithium ion electrolyte according to claim 10, wherein an XRD analysis of the composite comprises the following major peaks: TABLE-US-00008 Peak Position Relative Intensity 6.00 100 14.82 39.20 19.51 14.04 22.96 15.65 29.12 20.20 33.33 15.58 33.42 15.45.

12. A solid-state lithium ion electrolyte, comprising: a composite material of formula (III):
Li.sub.y(M1).sub.x1Si.sub.2-x2(M2).sub.x2Al.sub.1-x3(M3).sub.x3O.sub.7  (III) wherein x1 is from greater than 0 to less than 1, x2 is from greater than 0 to less than 1, x3 is from greater than 0 to less than 1, y is a value such that the composite of formula (III) is charge neutral, M1 is at least one element selected from a group 1 element, a group 2 element and a group 12 element, M2 is at least one element selected from a group 13 element, a group 14 element, and a group 15 element, and M3 is at least one element selected from a group 3 element, a group 4 element, a group 13 element, a group 14 element and a group 15 element.

13. The solid state lithium ion electrolyte according to claim 12, wherein a lithium ion (Li.sup.+) conductivity of the solid state lithium ion electrolyte is at least 10.sup.−6 S/cm at 300K.

14. The solid state lithium ion electrolyte according to claim 12, wherein an activation energy of the composite of formula (III) is 0.40 eV or less, and, the composite of formula (III) comprises a crystal lattice structure having a trigonal unit cell.

15. The solid state lithium ion electrolyte according to claim 12, wherein an XRD analysis of the composite comprises the following major peaks: TABLE-US-00009 Peak Position Relative Intensity 19.56 9.06 25.28 100 47.58 20.94 56.08 9.61 64.75 10.64.

16. A solid-state lithium ion electrolyte, comprising: a composite material of formula (IV):
Li.sub.y(M1).sub.x1 Si.sub.2-x2(M2).sub.x2Be.sub.1-x3(M3).sub.x3O.sub.7  (IV) wherein x1 is from greater than 0 to less than 2, x2 is from greater than 0 to less than 1, x3 is from greater than 0 to less than 1, y is a value such that the composite of formula (IV) is charge neutral, M1 is at least one element selected from the group of elements consisting of a group 1 element, a group 2 element and a group 12 element, M2 is at least one element selected from a group 13 element, a group 14 element, and a group 15 element, and M3 is at least one element selected from a group 1 element, a group 2 element, a group 12 element and a group 13 element.

17. The solid state lithium ion electrolyte according to claim 16, wherein a lithium ion (Li.sup.+) conductivity of the solid state lithium ion electrolyte is at least 10.sup.−6 S/cm at 300K.

18. The solid state lithium ion electrolyte according to claim 16, wherein an activation energy of the composite of formula (I) is 0.40 eV or less.

19. The solid state lithium ion electrolyte according to claim 16, wherein the composite of formula (IV) comprises a crystal lattice structure having an orthorhombic unit cell.

20. The solid state lithium ion electrolyte according to claim 16, wherein an XRD analysis of the composite comprises the following major peaks: TABLE-US-00010 Peak Position Relative Intensity 23.09 80.7 23.85 60.01 23.99 62.79 26.20 24.78 34.42 100 36.30 32.57 38.47 73.38 39.67 28.52 41.26 31.18 64.09 40.17.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The patent or application file contains at least one drawing executed in color. 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.

(2) FIG. 1 shows the crystal structure of Li.sub.6Si.sub.2O.sub.7.

(3) FIG. 2 shows the XRD analysis of the crystal structure of Li.sub.6Si.sub.2O.sub.7.

(4) FIG. 3 shows a table listing the peak positions and intensity for peaks of relative intensity of 1 or greater compared to the peak of greatest intensity in the XRD analysis of Li.sub.6Si.sub.2O.sub.7 in FIG. 2.

(5) FIG. 4 shows the crystal structure of Li.sub.10Si.sub.2PbO.sub.10.

(6) FIG. 5 shows the XRD analysis of the crystal structure of Li.sub.10Si.sub.2Pb.sub.10.

(7) FIG. 6 shows a table listing the peak positions and intensity for peaks of relative intensity of 1 or greater compared to the peak of greatest intensity in the XRD analysis of FIG. 5.

(8) FIG. 7 shows the crystal structure of LiAlSiO.sub.4.

(9) FIG. 8 shows the XRD analysis of the crystal structure of LiAlSiO.sub.4.

(10) FIG. 9 shows a table listing the peak positions and intensity for peaks of relative intensity of 1 or greater compared to the peak of greatest intensity in the XRD analysis of FIG. 8.

(11) FIG. 10 shows the crystal structure of Li.sub.2BeSiO.sub.4.

(12) FIG. 11 shows the XRD analysis of the crystal structure of Li.sub.2BeSiO.sub.4.

(13) FIG. 12 shows a table listing the peak positions and intensity for peaks of relative intensity of 1 or greater compared to the peak of greatest intensity in the XRD analysis of FIG. 11.

(14) FIG. 13 shows the crystal structure of Li.sub.2.4Zn.sub.4.4Si.sub.5.2∘.sub.16.

(15) FIG. 14 shows the XRD analysis of the crystal structure of Li.sub.2.4Zn.sub.4.4Si.sub.5.2◯.sub.16.

(16) FIG. 15 shows a table listing the peak positions and intensity for peaks of relative intensity of 1 or greater compared to the peak of greatest intensity in the XRD analysis of FIG. 14.

(17) FIG. 16 shows an Arrhenius plot of Li.sup.+ diffusivity (D) in Li.sub.10Si.sub.2PbO.sub.10 and Li.sub.6Si.sub.2O.sub.7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(18) Throughout this description, the terms “electrochemical cell” and “battery” may be employed interchangeably unless the context of the description clearly distinguishes an electrochemical cell from a battery. Further the terms “solid-state electrolyte” and “solid-state ion conductor” may be employed interchangeably unless explicitly specified differently.

(19) Structural characteristics of effective Li.sup.+ conducting crystal lattices have been described by Ceder et al. (Nature Materials, 14, 2015, 1026-1031) in regard to known Li.sup.+ ion conductors Li.sub.10GeP.sub.2S.sub.12 and Li.sub.7P.sub.3S.sub.11, where the sulfur sublattice of both materials was shown to very closely match a bcc lattice structure. Further, Li.sup.+ ion hopping across adjacent tetrahedral coordinated Li.sup.+ lattice sites was indicated to offer a path of lowest activation energy.

(20) The inventors are conducting ongoing investigations of new lithium composite compounds in order to identify materials having the properties which may serve as solid-state electrolytes in solid state lithium batteries. In the course of this ongoing study and effort the inventors have developed and implemented a methodology to identify composite materials which have chemical and structural properties which have been determined by the inventors as indicators of lithium ion conductance suitable to be a solid state electrolyte for a lithium-ion battery.

(21) To qualify as solid state electrolyte in practical applications, the material must meet several certain criteria. First, it should exhibit desirable Li-ion conductivity, usually no less than 10.sup.−6 S/cm at room temperature. Second, the material should have good stability against chemical, electrochemical and thermal degradation. Third, the material should have low grain boundary resistance for usage in all solid-state battery. Fourth, the synthesis of the material should be easy and the cost should not be high.

(22) A criterion of this methodology requires that to qualify as solid state electrolyte in practical application, the material must exhibit desirable Li-ion conductivity, usually no less than 10.sup.−6 S/cm at room temperature. Thus, ab initio molecular dynamics simulation studies were applied to calculate the diffusivity of Li ion in the lattice structures of selected silicate materials. In order to accelerate the simulation, the calculation was performed at high temperatures and the effect of excess Li or Li vacancy was considered. In order to create excess Li or Li vacancy, aliovalent replacement of cation or anions may be evaluated. Thus, Li vacancy was created by, for example, partially substituting Si with aliovalent cationic species while compensating the charge neutrality with Li vacancy or excess Li. For example, replacing 50% of Si in Li.sub.10Si.sub.2PbO.sub.10 with P results in the formation of Li.sub.9PSiPbO.sub.10.

(23) The diffusivity at 300 K was determined according to equation (1)
D=D.sub.0exp(−E.sub.a/k.sub.bT)  equation (1)
where D.sub.0, E.sub.a and k.sub.b are the pre-exponential factor, activation energy and Boltzmann constant, respectively. The conductivity is related with the calculated diffusivity according to equation (II):
σ=D.sub.300ρe.sup.2/k.sub.bT  equation (11)
where ρ is the volumetric density of Li ion and e is the unit charge.

(24) The anionic lattice of Li-ion conductors has been shown to match certain lattice types (see Nature Materials, 14, 2015, 2016). Therefore, in the anionic lattice of the potential Li.sup.+ ion conductor is compared to the anionic lattice of Li.sup.+ ion conductor known to have high conductivity.

(25) Thus, selected lithium silicate compounds were compared to Li-containing compounds reported in the inorganic crystal structure database (FIZ Karlsruhe ICSD—https://icsd.fiz-karlsruhe.de) and evaluated in comparison according to an anionic lattice matching method developed by the inventors for this purpose and described in copending U.S. application Ser. No. 15/597,651, filed May 17, 2017, to match the lattice of these compounds to known Li-ion conductors.

(26) According to the anionic lattice matching method described in copending U.S. application Ser. No. 15/597,651, an atomic coordinate set for the compound lattice structure may be converted to a coordinate set for only the anion lattice. The anions of the lattice are substituted with the anion of the comparison material and the obtained unit cell rescaled. The x-ray diffraction data for modified anion-only lattice may be simulated and an n×2 matrix generated from the simulated diffraction data. Quantitative structural similarity values can be derived from the n×2 matrices.

(27) The purpose of anionic lattice matching is to further identify compounds with greatest potential to exhibit high Li.sup.+ conductivity. From this work, the compounds described in the embodiments which follow were determined to be potentially suitable as a solid-state Li.sup.+ conductors.

(28) Ab initio molecular dynamics (AIMD) simulation was then applied to predict the conductivity of the targeted lithium silicates. The initial structures were statically relaxed and were set to an initial temperature of 100 K. The structures were then heated to targeted temperatures (750-1150 K) at a constant rate by velocity scaling over a time period of 2 ps. The total time of AIMD simulations were in the range of 200 to 400 ps. A typical example of the calculated diffusivity as a function of temperature is shown in FIG. 1. The Li.sup.+ diffusivity at different temperatures from 750-1150 K follows an Arrhenius-type relationship.

(29) Applying equation (I) above the diffusivity at 300 K was determined and then the conductivity may be determined using the link between conductivity and diffusivity of equation (II).

(30) Accordingly, the first embodiment provides a solid-state lithium ion electrolyte, comprising: a composite material of formula (I):
Li.sub.y(M1).sub.x1 Si.sub.2-x2(M2).sub.x2O.sub.7  (I)

(31) wherein x1 is a number from 0 to 6 inclusive of 0 and 6, x2 is a number from 0 to 2, inclusive of 0 and 2, and y is a value such that the composite of formula (I) is charge neutral, wherein M1 is at least one element selected from the group of elements consisting of a group 1 element, a group 2 element and a group 12 element, and M2 is at least one element selected from the group of elements consisting of a group 13 element, a group 14 element, and a group 15 element.

(32) The composite materials of formula (I) have a crystal structure comprising tetragonal unit cell (P42/m) with lattice parameters: a=7.72 Å and c=4.88 Å. The lithium ion (Li.sup.+) conductivities of the solid state lithium ion electrolytes of formula (I) are at least 10.sup.−5 S/cm at 300K and the activation energy of the composite of formula (I) is 0.4 eV or less.

(33) In a special aspect of the first embodiment the composite of formula (I) may be a material of formula (Ia):
Li.sub.6Si.sub.2O.sub.7  (Ia).

(34) The activation energy and room temperature conductivity determined for the composite of formula 1(a) are shown in Table 1. FIG. 1 shows a diagram of the lattice structure for the composite of formula (Ia) and FIG. 2 shows a computer generated XRD analysis of the composite of formula (Ia) The Table of FIG. 3 lists the respective XRD peaks and their relative intensities compared to the peak of greatest intensity in the XRD analysis. The major charateristic peaks are listed in Table 2.

(35) TABLE-US-00001 TABLE 2 Major Peaks in XRD Analysis of Li.sub.6Si.sub.2O.sub.7 Peak Position Relative Intensity 21.55 24.8 24.47 52.16 25.82 100 31.76 21.87 36.84 31.47 41.38 19.87 47.12 25.34

(36) In a second embodiment, a solid-state lithium ion electrolyte, comprising: a composite material of formula (II) is provided:
Li.sub.y(M1).sub.x1 Si.sub.2-x2(M2).sub.x2Pb.sub.1-x3(M3).sub.x3O.sub.7  (II)

(37) wherein x1 is a number from 0 to 10 inclusive of 0 and 10, x2 is a number from 0 to 2, inclusive of 0 and 2, x3 is a number from 0 to 1, inclusive of 0 and 1, and y is a value such that the composite of formula (II) is charge neutral, M1 is at least one element selected from the group of elements consisting of a group 1 element, a group 2 element and a group 12 element, M2 is at least one element selected from the group of elements consisting of a group 13 element, a group 14 element, and a group 15 element, M3 is at least one element selected from a group 2 element, a group 12 element, a group 13 element, a group 14 element and a group 15 element.

(38) The composite materials of formula (II) have a crystal structure comprising a monoclinic unit cell (C2/m) with lattice parameters: a=29.85 Å, b=6.11 Å and c=5.13 Å. The lithium ion (Li.sup.+) conductivities of the solid state lithium ion electrolytes of formula (II) are at least 10.sup.−5 S/cm at 300K and the activation energy of the composite of formula (I) is 0.45 eV or less.

(39) In a further aspect of the second embodiment, the composite of formula (II) comprises a crystal lattice structure having a monoclinic unit cell.

(40) In a special aspect of the second embodiment the composite of formula (II) is a material of formula (IIa):
Li.sub.10Si.sub.2PbO.sub.10  ((IIa).

(41) FIG. 4 shows a diagram of the lattice structure of the composite of formula (IIa) and FIG. 5 shows a computer generated XRD analysis of the composite of formula (IIa). The Table of FIG. 6 lists the respective XRD peaks and their relative intensities compared to the peak of greatest intensity. Table 3 lists the major characteristic peaks.

(42) TABLE-US-00002 TABLE 3 Major Peaks in XRD Analysis of Li.sub.10Si.sub.2PbO.sub.10 Peak Position Relative Intensity 6.00 100 14.82 39.20 19.51 14.04 22.96 15.65 29.12 20.20 33.33 15.58 33.42 15.45

(43) In a third embodiment, a solid-state lithium ion electrolyte, comprising:

(44) a composite material of formula (III) is provided:
Li.sub.y(M1).sub.x1Si.sub.2-x2(M2).sub.x2Al.sub.1-x3(M3).sub.x3O.sub.7  (III)

(45) wherein x1 is from 0 to 1, inclusive of 0 and 1, x2 is from 0 to 1, inclusive of 0 and 1, x3 is from 0 to 1, inclusive of 0 and 1, and y is a value such that the composite of formula (III) is charge neutral, M1 is at least one element selected from a group 1 element, a group 2 element and a group 12 element, M2 is at least one element selected from a group 13 element, a group 14 element, and a group 15 element, and M3 is at least one element selected from a group 3 element, a group 4 element, a group 13 element, a group 14 element and a group 15 element.

(46) The composite materials of formula (III) have a crystal structure comprising a trigonal unit cell (R3) with lattice parameters: a=13.53 Å and c=9.04 Å. The lithium ion (Li.sup.+) conductivities of the solid state lithium ion electrolytes of formula (III) are at least 10.sup.−6 S/cm at 300K and the activation energy of the composite of formula (I) is 0.40 eV or less.

(47) In a special aspect of the third embodiment the composite of formula (III) is a material of formula (IIIa):
LiAlSiO.sub.4  (IIIa).

(48) FIG. 7 shows a diagram of the lattice structure of the composite of formula (IIIa) and FIG. 8 shows the computer generated XRD analysis of the composite of formula (IIIa). The Table of FIG. 9 shows the peaks and relative intensities compared to the peak of greatest intensity for the XRD analysis shown in FIG. 8. Table 4 shows the major peaks in the XRD analysis.

(49) TABLE-US-00003 TABLE 4 Major Peaks in XRD Analysis of LiAlSiO.sub.4 Peak Position Relative Intensity 19.56 9.06 25.28 100 47.58 20.94 56.08 9.61 64.75 10.64

(50) In a further special aspect of the third embodiment the composite of formula (III) is the material of formula (IIIb):
Li.sub.1.33Al.sub.1.33Si.sub.0.67O.sub.4  (IIIb).

(51) In a fourth embodiment a solid-state lithium ion electrolyte, comprising:

(52) a composite material of formula (IV) is provided:
Li.sub.y(M1).sub.x1Si.sub.2-x2(M2).sub.x2Be.sub.1-x3(M3).sub.x3O.sub.7  (IV)

(53) wherein x1 is from 0 to 2, inclusive of 0 and 2, x2 is from 0 to 1, inclusive of 0 and 1, x3 is from 0 to 1, inclusive of 0 and 1, and y is a value such that the composite of formula (IV) is charge neutral, M1 is at least one element selected from the group of elements consisting of a group 1 element, a group 2 element and a group 12 element, M2 is at least one element selected from a group 13 element, a group 14 element, and a group 15 element, and M3 is at least one element selected from a group 1 element, a group 2 element, a group 12 element and a group 13 element.

(54) The composite materials of formula (IV) have a crystal structure comprising an orthorhombic unit cell (Pmnb) with lattice parameters: a=6.41 Å, b=10.52 Å and c=5.04 Å. The lithium ion (Li.sup.+) conductivities of the solid state lithium ion electrolytes of formula (IV) are at least 10.sup.−6 S/cm at 300K and the activation energy of the composite of formula (I) is 0.4 eV or less.

(55) In a special aspect of the fourth embodiment the composite of formula (IV) is a material of formula (IVa):
Li.sub.2BeSiO.sub.4  (IVa).

(56) FIG. 10 shows a diagram of the lattice structure of the composite of formula (IVa) and FIG. 11 shows a computer generated XRD analysis of the composite of formula (IVa). The Table of FIG. 12 lists the peaks and their relative intensities compared to the peak of greatest intensity of the XRD analysis of FIG. 11. Table 5 shows the major peaks in the XRD analysis.

(57) TABLE-US-00004 TABLE 5 Major Peaks in XRD Analysis of Li.sub.2BeSiO.sub.4 Peak Position Relative Intensity 23.09 80.7 23.85 60.01 23.99 62.79 26.20 24.78 34.42 100 36.30 32.57 38.47 73.38 39.67 28.52 41.26 31.18 64.09 40.17

(58) In a fifth embodiment, a solid-state lithium ion electrolyte, comprising: a composite material of formula (V) is provided:
Li.sub.2.4Zn.sub.4.4Si.sub.5.2O.sub.16  (V).

(59) The composite material of formula (V) has a crystal structure comprising a monoclinic unit cell (Pmnb) with lattice parameters: a=6.4 Å, b=10.5 Å and c=5.0 Å. FIG. 13 shows a diagram of the lattice structure and FIG. 14 shows a computer generated XRD analysis of composite of formula (V). The Table of FIG. 15 shows the peaks and their relative intensities compared to the peak of greatest intensity in the XRD analysis of FIG. 14. Table 6 shows the major peaks in the XRD analysis.

(60) TABLE-US-00005 TABLE 6 Major Peaks in XRD Analysis of Li.sub.2.4Zn.sub.4.4Si.sub.5.2O.sub.16 Peak Position Relative Intensity 21.86 69.54 22.44 65.65 24.45 60.49 27.85 35.59 32.73 100 34.09 75.78 34.24 39.79 35.60 95.85 39.40 54.39 42.20 33.36 57.55 35.15 60.16 59.58 68.48 38.12

(61) The lithium ion (Li.sup.+) conductivities of the solid state lithium ion electrolytes of formula (V) are at least 10.sup.−6 S/cm at 300K and the activation energy of the composite of formula (V) is 0.5 eV or less.

(62) TABLE-US-00006 TABLE 1 Activation energy and room temperature conductivity from AIMD simulations. composition E.sub.a (eV) σ (S/cm) Li.sub.6Si.sub.2O.sub.7 0.36 4 × 10.sup.−5 at 300 K Li.sub.10Si.sub.2PbO.sub.10 0.42 6 × 10.sup.−5 at 300 K Li.sub.2BeSiO.sub.4 0.39 7 × 10.sup.−6 at 300 K LiAlSiO.sub.4 1.1 × 10−1 at 1150 K

(63) Synthesis of the composite materials of the embodiments described above may be achieved by 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 papers: 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. 5 Ib, 199652 5.

(64) In further embodiments, the present application includes solid state lithium ion batteries containing the solid-state electrolytes described above. Solid-state batteries of these embodiments including metal-metal solid-state batteries may have higher charge/discharge rate capability and higher power density than classical batteries and may have the potential to provide high power and energy density.

(65) Thus, in further embodiments, solid-state batteries comprising: an anode; a cathode; and a solid state lithium ion electrolyte according to the embodiments described above, located between the anode and the cathode are provided.

(66) The anode may be any anode structure conventionally employed in a lithium ion battery. Generally such materials are capable of insertion and extraction of Li.sup.+ ions. Example anode active materials may include graphite, hard carbon, lithium titanate (LTO), a tin/cobalt alloy and silicon/carbon composites. In one aspect the anode may comprise a current collector and a coating of a 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 an aspect advantageously arranged with the solid-state lithium ion conductive materials described in the first and second embodiments, the anode may be lithium metal or a lithium metal alloy, optionally coated on a current collector. In one aspect, the anode may be a sheet of lithium metal serving both as active material and current collector.

(67) The cathode structure may be any conventionally employed in lithium ion batteries, including but not limited to composite lithium metal oxides such as, for example, lithium cobalt oxide (LiCoO.sub.2), lithium manganese oxide (LiMn.sub.2O.sub.4), lithium iron phosphate (LiFePO.sub.4) 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.

(68) In one aspect, the active cathode material may be a transition metal, preferably, silver or copper. A cathode based on such transition metal may not include a current collector.

(69) The above description is presented to enable a person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the preferred embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Thus, this 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. In this regard, certain embodiments within the invention may not show every benefit of the invention, considered broadly.