Mixed ionic and electronic conductor for solid state battery

Abstract

Disclosed are electrochemical devices, such as lithium ion battery electrodes, lithium ion conducting solid-state electrolytes, and solid-state lithium ion batteries including these electrodes and solid-state electrolytes. Also disclosed are methods for making such electrochemical devices. Also disclosed are composite electrodes for solid state electrochemical devices. The composite electrodes include one or more separate phases within the electrode that provide electronic and ionic conduction pathways in the electrode active material phase.

Claims

1. An electrode for an electrochemical device, the electrode comprising: a lithium host material phase; and a solid-state conductive material phase comprising a ceramic material having a crystal structure and a dopant in the crystal structure, the conductive material phase having a lithium-ion conductivity and a conductive material electronic conductivity wherein the conductive material electronic conductivity is greater than a reference electronic conductivity of a reference material comprising the ceramic material having the crystal structure without the dopant in the crystal structure, the conductive material phase filling at least part of a structure of the lithium host material phase, wherein the dopant is selected from the group consisting of transition metal ions and mixtures thereof, and wherein the electrode does not include a separate phase, other than the lithium host material phase and the solid-state conductive material phase, that provides an electrical pathway from a current collector to the lithium host material phase.

2. The electrode of claim 1 wherein: the ceramic material comprises an oxide including lithium, lanthanum, and zirconium, and the crystal structure is a garnet-type or garnet-like crystal structure.

3. The electrode of claim 1 wherein: the lithium-ion conductivity is greater than 10.sup.5 S/cm.

4. The electrode of claim 1 wherein: the dopant is present in the crystal structure at 0.05 to 3 weight percent based on a total weight of chemical elements in the crystal structure.

5. The electrode of claim 1 wherein: the conductive material electronic conductivity is greater than 10.sup.6 S/cm.

6. The electrode of claim 1 wherein: the conductive material electronic conductivity is greater than 10.sup.4 S/cm.

7. The electrode of claim 1 wherein: the ceramic material has a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, and wherein z is 10.875-13.125.

8. The electrode of claim 1 wherein: the ceramic material has the formula Li.sub.7La.sub.3Zr.sub.2O.sub.12.

9. The electrode of claim 1 wherein: the ceramic material has the formula Li.sub.6.25La.sub.2.7Zr.sub.2Al.sub.0.25O.sub.12, and is 0.125.

10. The electrode of claim 1 wherein: the dopant is selected from the group consisting of ions of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Fe, and mixtures thereof.

11. The electrode of claim 1 wherein: the dopant comprises cobalt ions.

12. An electrochemical device comprising: a cathode comprising a lithium host material phase; an anode comprising lithium metal, or a lithium host material phase; a solid-state electrolyte configured to facilitate the transfer of ions between the anode and the cathode; and a solid-state conductive material phase comprising a ceramic material having a crystal structure and a dopant in the crystal structure, the conductive material having a lithium-ion conductivity and an electronic conductivity wherein the electronic conductivity of the conductive material is greater than a reference electronic conductivity of a reference material comprising the ceramic material having the crystal structure without the dopant in the crystal structure, the conductive material filling at least part of at least one of a first structure of the lithium host material of the cathode or a second structure of the lithium host material of the anode, wherein the dopant is selected from the group consisting of transition metal ions and mixtures thereof, and wherein the cathode or the anode does not include a separate phase, other than the lithium host material phase and the solid-state conductive material phase, that provides an electrical pathway from a current collector to the lithium host material phase.

13. The electrochemical device of claim 12 wherein: the ceramic material comprises an oxide including lithium, lanthanum, and zirconium, and the crystal structure is a garnet-type or garnet-like crystal structure.

14. The electrochemical device of claim 12 wherein: the lithium-ion conductivity is greater than 10.sup.5 S/cm.

15. The electrochemical device of claim 12 wherein: the dopant is present in the crystal structure at 0.05 to 3 weight percent based on a total weight of chemical elements in the crystal structure.

16. The electrochemical device of claim 12 wherein: the conductive material electronic conductivity is greater than 10.sup.6 S/cm.

17. The electrochemical device of claim 12 wherein: the ceramic material has a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

18. The electrochemical device of claim 12 wherein: the ceramic material has the formula Li.sub.7La.sub.3Zr.sub.2O.sub.12.

19. The electrochemical device of claim 12 wherein: the ceramic material has the formula Li.sub.6.25La.sub.2.7Zr.sub.2Al.sub.0.25O.sub.12, and is 0.125.

20. The electrochemical device of claim 12 wherein: wherein the dopant is selected from the group consisting of ions of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Fe, and mixtures thereof.

21. The electrochemical device of claim 12 wherein: the dopant comprises cobalt ions.

22. The electrochemical device of claim 12 wherein: the conductive material fills at least part of the first structure.

23. The electrochemical device of claim 12 wherein: the conductive material fills at least part of the second structure.

24. The electrochemical device of claim 12 wherein: the lithium host material of the cathode is selected from the group consisting of lithium metal oxides wherein the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium, and lithium-containing phosphates having a general formula LiMPO.sub.4 wherein M is one or more of cobalt, iron, manganese, and nickel, and the conductive material fills at least part of the first structure.

25. The electrochemical device of claim 12 wherein: the lithium host material of the cathode is selected from the group consisting of lithium cobalt oxides, and the conductive material fills at least part of the first structure.

26. The electrochemical device of claim 12 wherein: the lithium host material of the cathode is selected from the group consisting of lithium nickel manganese cobalt oxides, and the conductive material fills at least part of the first structure.

27. The electrochemical device of claim 12 wherein: the lithium host material of the cathode is selected from the group consisting of lithium nickel cobalt aluminum oxides, and the conductive material fills at least part of the first structure.

28. The electrochemical device of claim 12 wherein: the anode comprises the lithium host material of the anode, the lithium host material of the anode is selected from the group consisting of graphite, lithium metal, lithium titanium oxides, hard carbon, tin/cobalt alloy, or silicon/carbon, and the conductive material fills at least part of the second structure.

29. The electrochemical device of claim 12 wherein: the anode comprises lithium metal.

30. The electrochemical device of claim 12 wherein: the solid-state electrolyte comprises a solid electrolyte material selected from the group consisting of any combination oxide or phosphate materials with the garnet, perovskite, NaSICON, and LiSICON phase or polymers.

31. The electrochemical device of claim 30 wherein: the solid electrolyte material has a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic of a lithium ion battery.

(2) FIG. 2 is a schematic of a lithium metal battery.

(3) FIG. 3 is a graph showing electronic and ionic conductivities of Li.sub.7La.sub.3Zr.sub.2O.sub.12 (LLZO) before and after doping with cobalt (Co).

DETAILED DESCRIPTION OF THE INVENTION

(4) In one non-limiting example application, an electrode according to embodiments of the invention can be used in a lithium ion battery as depicted in FIG. 1. The lithium ion battery 10 of FIG. 1 includes a current collector 12 (e.g., aluminum) in contact with a cathode 14. A solid state electrolyte 16 is arranged between the cathode 14 and an anode 18, which is in contact with a current collector 22 (e.g., aluminum). The current collectors 12 and 22 of the lithium ion battery 10 may be in electrical communication with an electrical component 24. The electrical component 24 could place the lithium ion battery 10 in electrical communication with an electrical load that discharges the battery or a charger that charges the battery.

(5) A suitable active material for the cathode 14 of the lithium ion battery 10 is a lithium host material capable of storing and subsequently releasing lithium ions. An example cathode active material is a lithium metal oxide wherein the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium. Non-limiting example lithium metal oxides are LiCoO.sub.2 (LCO), LiFeO.sub.2, LiMnO.sub.2 (LMO), LiMn.sub.2O.sub.4, LiNiO.sub.2 (LNO), LiNi.sub.xCo.sub.yO.sub.2, LiMn.sub.xCo.sub.yO.sub.2, LiMn.sub.xNi.sub.yO.sub.2, LiMn.sub.xNi.sub.yO.sub.4, LiNi.sub.xCo.sub.yAl.sub.zO.sub.2, LiNi.sub.1/3Mn.sub.1/3Co.sub.1/3O.sub.2 and others. Another example of cathode active materials is a lithium-containing phosphate having a general formula LiMPO.sub.4 wherein M is one or more of cobalt, iron, manganese, and nickel, such as lithium iron phosphate (LFP) and lithium iron fluorophosphates. Many different elements, e.g., Co, Mn, Ni, Cr, Al, or Li, may be substituted or additionally added into the structure to influence electronic conductivity, ordering of the layer, stability on delithiation and cycling performance of the cathode materials. The cathode active material can be a mixture of any number of these cathode active materials.

(6) A suitable active material for the anode 18 of the lithium ion battery 10 is a lithium host material capable of incorporating and subsequently releasing the lithium ion such as graphite, a lithium metal oxide (e.g., lithium titanium oxide), hard carbon, a tin/cobalt alloy, or silicon/carbon. The anode active material can be a mixture of any number of these anode active materials.

(7) A suitable solid state electrolyte 16 of the lithium ion battery 10 includes an electrolyte material having the formula Li.sub.uRe.sub.vM.sub.wA.sub.xO.sub.y, wherein Re can be any combination of elements with a nominal valance of +3 including La, Nd, Pr, Pm, Sm, Sc, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb, and Lu; M can be any combination of metals with a nominal valance of +3, +4, +5 or +6 including Zr, Ta, Nb, Sb, W, Hf, Sn, Ti, V, Bi, Ge, and Si; A can be any combination of dopant atoms with nominal valance of +1, +2, +3 or +4 including H, Na, K, Rb, Cs, Ba, Sr, Ca, Mg, Fe, Co, Ni, Cu, Zn, Ga, Al, B, and Mn; u can vary from 3-7.5; can vary from 0-3; w can vary from 0-2; x is 0-2; and y can vary from 11-12.5.
In a non-limiting example embodiment of the invention, the electrolyte material has the chemical formula of Li.sub.6.25La.sub.2.7Zr.sub.2Al.sub.0.25O.sub.12, wherein is 0.125.

(8) In another non-limiting example application, an electrode according to embodiments of the invention can be used in a lithium metal battery as depicted in FIG. 2. The lithium metal battery 110 of FIG. 2 includes a current collector 112 in contact with a cathode 114. A solid state electrolyte 116 is arranged between the cathode 114 and an anode 118, which is in contact with a current collector 122. The current collectors 112 and 122 of the lithium metal battery 110 may be in electrical communication with an electrical component 124. The electrical component 124 could place the lithium metal battery 110 in electrical communication with an electrical load that discharges the battery or a charger that charges the battery. A suitable active material for the cathode 114 of the lithium metal battery 110 is one or more of the lithium host materials listed above, or porous carbon (for a lithium air battery), or a sulfur containing material (for a lithium sulfur battery). A suitable active material for the anode 118 of the lithium metal battery 110 is lithium metal. A suitable solid state electrolyte material for the solid state electrolyte 116 of the lithium metal battery 110 is one or more of the solid state electrolyte materials listed above.

(9) The present invention provides embodiments of an electrode that provide improved electronic and ionic conduction pathways in the electrode active material phase (e.g., lithium host material) of a cathode or an anode suitable for use in the lithium ion battery 10 of FIG. 1 or the lithium metal battery 110 of FIG. 2.

(10) Attractive solid-state electrolytes for the electrolyte layer in solid state batteries require ionic transference numbers approaching 1, i.e., high ionic transport and low electronic transport. LLZO is able to reach ionic transference numbers of 0.99999 [see, Buschmann et al., Physical Chemistry Chemical Physics 2011, 13, 19378]. However, within an all solid state composite electrode (e.g., cathode), it is desirable to use a solid-state conductive material that has an ionic transference number less than 1, such that the solid-state conductive material also has appreciable electronic conductivity, also known as a mixed ionic electronic conductor.

(11) Transition metal doping of garnet LLZO phase can greatly increase electronic conductivity while ionic conductivity is minimally changed. Cobalt, in particular, readily dopes the LLZO structure and lends significant electronic conductivity, as shown in FIG. 3. In FIG. 3, undoped Li.sub.7La.sub.3Zr.sub.2O.sub.12 (LLZO) has the lower ionic conductivity and the lower electronic conductivity values. In FIG. 3, the doping was with about 0.3 wt. % Co.sub.3O.sub.4 in the LLZO as measured by an X-ray fluorescence analyzer (XRF). The 0.3 wt. % Co.sub.3O.sub.4 doping in the LLZO resulted in the higher ionic conductivity and the higher electronic conductivity values shown in FIG. 3.

(12) Cobalt doped LLZO can be produced by direct solid state reaction of cobalt oxides or cobalt metal and LLZO during synthesis. Additionally, cobalt doped LLZO can be generated in-situ by co-sintering cobalt containing cathode materials such as LiCoO.sub.2, lithium nickel manganese cobalt oxide (NMC), or lithium nickel cobalt aluminum oxide (NCA). In another embodiment, cobalt is diffused into the LLZO at a temperature (e.g., 600-1000 C.) from cobalt or cobalt oxide species in the gas phase. Although cobalt is used as an example, it is expected that other dopants including transition metals can similarly increase the electronic conductivity while minimally changing the ionic conductivity.

(13) Solid-State Electrolyte

(14) In one embodiment, the invention provides a solid-state electrolyte for an electrochemical device. The solid-state electrolyte can be used in a composite cathode to provide for facile movement of ions and electrons to the electrode active material phase. The solid-state electrolyte comprises a conductive material comprising a ceramic material having a crystal structure and a dopant in the crystal structure. The conductive material has a lithium-ion conductivity and a conductive material electronic conductivity wherein the conductive material electronic conductivity is greater than a reference electronic conductivity of a reference material comprising the ceramic material having the crystal structure without the dopant in the crystal structure. The ceramic material can comprise an oxide including lithium, lanthanum, and zirconium having a garnet-type or garnet-like crystal structure, and the dopant can be selected from the group consisting of transition metal ions and mixtures thereof. The dopant may be present in the crystal structure at 0.05 to 3 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at greater than 0.01 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at 0.1 to 1 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at 0.05 to 1.5 weight percent based on a total weight of the chemical elements in the crystal structure. For example, transition metal doping of garnet LLZO phase can greatly increase electronic conductivity while ionic conductivity is minimally changed. Cobalt, in particular, readily dopes the LLZO structure and lends significant electronic conductivity. The transition metal dopant (e.g., cobalt) may be from any appropriate transition metal containing source.

(15) The solid-state electrolyte can have a lithium-ion conductivity greater than 10.sup.5 S/cm, and preferably greater than 10.sup.4 S/cm. The solid-state electrolyte can have an electronic conductivity greater than 10.sup.6 S/cm, preferably greater than 10.sup.5 S/cm, and more preferably greater than 10.sup.4 S/cm.

(16) The ceramic material of the solid-state electrolyte can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, and wherein z is 10.875-13.125.
In one non-limiting example, the ceramic material has the formula Li.sub.7La.sub.3Zr.sub.2O.sub.12. In another non-limiting example, the ceramic material has the formula Li.sub.6.25La.sub.2.7Zr.sub.2Al.sub.0.25O.sub.12, wherein is 0.125.

(17) In the solid-state electrolyte, the dopant can be selected from the group consisting of ions of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. In one non-limiting example, the dopant comprises cobalt ions.

(18) Composite Electrodes

(19) In another embodiment, the invention provides a composite electrode for an electrochemical device. The electrode may be a cathode or an anode. The electrode comprises a lithium host material having a structure (which may be porous); and a solid-state conductive material comprising a ceramic material having a crystal structure and a dopant in the crystal structure. The conductive material has a lithium-ion conductivity and a conductive material electronic conductivity wherein the conductive material electronic conductivity is greater than a reference electronic conductivity of a reference material comprising the ceramic material having the crystal structure without the dopant in the crystal structure. The conductive material fills at least part (or all) of the structure of the electrode. The ceramic material of the solid-state conductive material of the electrode can comprise an oxide including lithium, lanthanum, and zirconium having a garnet-type or garnet-like crystal structure, and the dopant can be selected from the group consisting of transition metal ions and mixtures thereof. The dopant may be present in the crystal structure at 0.05 to 3 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at greater than 0.01 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at 0.1 to 1 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at 0.05 to 1.5 weight percent based on a total weight of the chemical elements in the crystal structure. For example, transition metal doping of garnet LLZO phase can greatly increase electronic conductivity while ionic conductivity is minimally changed. Cobalt, in particular, readily dopes the LLZO structure and lends significant electronic conductivity. The transition metal dopant (e.g., cobalt) may be from any appropriate transition metal containing source.

(20) The solid-state conductive material of the electrode can have a lithium-ion conductivity greater than 10.sup.5 S/cm, and preferably greater than 10.sup.4 S/cm. The solid-state conductive material of the electrode can have an electronic conductivity greater than 10.sup.6 S/cm, preferably greater than 10.sup.5 S/cm, and more preferably greater than 10.sup.4 S/cm.

(21) The ceramic material of the solid-state conductive material of the electrode can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, and wherein z is 10.875-13.125.
In one non-limiting example, the ceramic material of the solid-state conductive material of the electrode has the formula Li.sub.7La.sub.3Zr.sub.2O.sub.12. In another non-limiting example, the ceramic material of the solid-state conductive material of the electrode has the formula Li.sub.6.25La.sub.2.7Zr.sub.2Al.sub.0.25O.sub.12, wherein is 0.125.

(22) In the solid-state conductive material of the electrode, the dopant can be selected from the group consisting of ions of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. In one non-limiting example, the dopant comprises cobalt ions.

(23) Electrochemical Devices

(24) In one embodiment, the invention provides an electrochemical device, such as the lithium ion battery 10 of FIG. 1 or the lithium metal battery 110 of FIG. 2. The electrochemical device comprises a cathode, an anode, and a solid-state electrolyte configured to facilitate the transfer of ions between the anode and the cathode. The cathode can comprise a lithium host material having a first structure (which may be porous). The anode can comprise a lithium metal, or a lithium host material having a second structure (which may be porous).

(25) In the electrochemical device, a solid-state conductive material comprising a ceramic material having a crystal structure and a dopant in the crystal structure fills at least part (or all) of the first structure in the lithium host material of the cathode and/or a second structure of the lithium host material of the anode (in the case of a lithium ion battery). Typically, the lithium host materials are sintered.

(26) The conductive material has a lithium-ion conductivity and a conductive material electronic conductivity wherein the conductive material electronic conductivity is greater than a reference electronic conductivity of a reference material comprising the ceramic material having the crystal structure without the dopant in the crystal structure. The ceramic material of the solid-state conductive material of one or both of the electrode(s) of the electrochemical device can comprise an oxide including lithium, lanthanum, and zirconium having a garnet-type or garnet-like crystal structure, and the dopant can be selected from the group consisting of transition metal ions and mixtures thereof. The dopant may be present in the crystal structure at 0.05 to 3 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at greater than 0.01 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at 0.1 to 1 weight percent based on a total weight of the chemical elements in the crystal structure, or the dopant may be present in the crystal structure at 0.05 to 1.5 weight percent based on a total weight of the chemical elements in the crystal structure. For example, transition metal doping of garnet LLZO phase can greatly increase electronic conductivity while ionic conductivity is minimally changed. Cobalt, in particular, readily dopes the LLZO structure and lends significant electronic conductivity. The transition metal dopant (e.g., cobalt) may be from any appropriate transition metal containing source.

(27) The solid-state conductive material of one or both of the electrodes of the electrochemical device can have a lithium-ion conductivity greater than 10.sup.5 S/cm, and preferably greater than 10.sup.4 S/cm. The solid-state conductive material of one or both of the electrodes of the electrochemical device can have an electronic conductivity greater than 10.sup.6 S/cm, preferably greater than 10.sup.5 S/cm, and more preferably greater than 10.sup.4 S/cm.

(28) The ceramic material of the solid-state conductive material of one or both of the electrodes of the electrochemical device can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, and wherein z is 10.875-13.125.
In one non-limiting example, the ceramic material of the solid-state conductive material of one or both of the electrode(s) of the electrochemical device has the formula Li.sub.7La.sub.3Zr.sub.2O.sub.12. In another non-limiting example, the ceramic material of the solid-state conductive material of one or both of the electrodes of the electrochemical device has the formula Li.sub.6.25La.sub.2.7Zr.sub.2Al.sub.0.25O.sub.12, wherein is 0.125.

(29) In the solid-state conductive material of one or both of the electrodes of the electrochemical device, the dopant can be selected from the group consisting of ions of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. In one non-limiting example, the dopant comprises cobalt ions.

(30) The lithium host material of the cathode of the electrochemical device can be selected from the group consisting of lithium metal oxides wherein the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium, and lithium-containing phosphates having a general formula LiMPO.sub.4 wherein M is one or more of cobalt, iron, manganese, and nickel. The lithium host material of the cathode of the electrochemical device can be selected from the group consisting of lithium cobalt oxides. The lithium host material of the cathode of the electrochemical device can be selected from the group consisting of lithium nickel manganese cobalt oxides. The lithium host material of the cathode of the electrochemical device can be selected from the group consisting of lithium nickel cobalt aluminum oxides.

(31) The lithium host material of the anode of the electrochemical device (in the case of a lithium ion battery) can be selected from the group consisting of graphite, lithium metal, lithium titanium oxides, hard carbon, tin/cobalt alloy, or silicon/carbon. In a lithium metal battery, the anode comprises lithium metal.

(32) The solid-state electrolyte facilitating the transfer of ions between the anode and the cathode of the electrochemical device can comprise a solid electrolyte material selected from the group consisting of any combination oxide or phosphate materials with the garnet, perovskite, NaSICON, and LiSICON phase or polymers. The solid electrolyte material can have has a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

(33) The cathode and the anode of the electrochemical device can comprise a current collector configured to place the electrochemical device in electrical communication with an electrical load that discharges the battery or a charger that charges the battery.

(34) Methods for Forming a Solid Electrolyte Material

(35) In one embodiment, the invention provides a method for forming a solid electrolyte material. In this method, a first solid comprising a lithium oxide or a lithium salt, a second solid comprising a lanthanum oxide or a lanthanum salt; and a third solid comprising a zirconium oxide or a zirconium salt and a fourth solid comprising a transition metal, a transition metal oxide or a transition metal salt are combined to form a mixture. The mixture is calcined, preferably at a temperature from 400 C. to 1200 C., to form a solid electrolyte material having a lithium-ion conductivity and a solid electrolyte material electronic conductivity. In this method, the fourth solid is selected such that the solid electrolyte material electronic conductivity is greater than a reference electronic conductivity of a reference material having a formula of Li.sub.7La.sub.3Zr.sub.2O.sub.12.

(36) The fourth solid can comprises a transition metal, and the transition metal can be selected from the group consisting of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. The fourth solid can comprise a transition metal oxide, and the transition metal oxide can be selected from the group consisting of oxides of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. The fourth solid can comprise a transition metal salt, and the transition metal salt can be selected from the group consisting of salts of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. The fourth solid can comprise cobalt oxide or cobalt metal.

(37) In another embodiment, the invention provides a method for forming a solid electrolyte material. In this method, a first solid comprising a lithium oxide or a lithium salt, a second solid comprising a lanthanum oxide or a lanthanum salt; and a third solid comprising a zirconium oxide or a zirconium salt are combined. The mixture is calcined, preferably at a temperature from 400 C. to 1200 C., to form a ceramic material having a crystal structure. The crystal structure is doped with a transition metal ion to form a solid electrolyte material having a lithium-ion conductivity and a solid electrolyte material electronic conductivity. The transition metal ion is selected such that the solid electrolyte material electronic conductivity is greater than a reference electronic conductivity of a reference material having a formula of Li.sub.7La.sub.3Zr.sub.2O.sub.12.

(38) The ceramic material of this method can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

(39) In one version of this method, the transition metal ion is diffused into the crystal structure using gas phase transport from a solid comprising a transition metal, a transition metal oxide or a transition metal salt. The transition metal can be selected from the group consisting of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, and the transition metal oxide can be selected from the group consisting of oxides of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, and the transition metal salt can be selected from the group consisting of salts of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. In one version of this method, one or more cobalt ions are diffused into the crystal structure using gas phase transport from a powder comprising a cobalt metal, a cobalt oxide or a cobalt salt.

(40) Methods for Forming a Composite Electrode

(41) In one embodiment, the invention provides a method for forming a composite electrode for an electrochemical device. In this method, a slurry is cast on a surface to form a layer, wherein the slurry comprises (i) a lithium host material, (ii) a ceramic material comprising an oxide including lithium, lanthanum, and zirconium, and having a garnet-type or garnet-like crystal structure, and (iii) a dopant comprising a transition metal, a transition metal oxide or a transition metal salt. The layer is sintered, preferably at a temperature from 400 C. to 1200 C., to form the electrode.

(42) In this method, the lithium host material, typically for a cathode, can be selected from the group consisting of lithium metal oxides wherein the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium, and lithium-containing phosphates having a general formula LiMPO.sub.4 wherein M is one or more of cobalt, iron, manganese, and nickel. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium cobalt oxides. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium nickel manganese cobalt oxides. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium nickel cobalt aluminum oxides. The lithium host material, typically for an anode, can be selected from the group consisting of graphite, lithium metal, lithium titanium oxides, hard carbon, tin/cobalt alloy, or silicon/carbon.

(43) For the dopant of this method, the transition metal can be selected from the group consisting of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, or the transition metal oxide can be selected from the group consisting of oxides of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, or the transition metal salt can be selected from the group consisting of salts of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. The dopant can provide cobalt ions in a crystal structure of the ceramic material.

(44) In this method, the ceramic material can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

(45) In another embodiment, the invention provides a method for forming a composite electrode for an electrochemical device. In this method, a slurry is cast on a surface to form a layer, wherein the slurry comprises a lithium host material. The layer is sintered, preferably at a temperature from 400 C. to 1200 C., to form an electrode active material having a porous structure therein; and at least part (or all) of the porous structure is filled with a solid-state conductive material comprising a ceramic material having a crystal structure and a dopant in the crystal structure. The conductive material has a lithium-ion conductivity and a conductive material electronic conductivity wherein the conductive material electronic conductivity is greater than a reference electronic conductivity of a reference material comprising the ceramic material having the crystal structure without the dopant in the crystal structure. The ceramic material can be an oxide including lithium, lanthanum, and zirconium, the crystal structure can be a garnet-type or garnet-like crystal structure, and the dopant can be selected from the group consisting of transition metal ions and mixtures thereof.

(46) In this method, the lithium host material, typically for a cathode, can be selected from the group consisting of lithium metal oxides wherein the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium, and lithium-containing phosphates having a general formula LiMPO.sub.4 wherein M is one or more of cobalt, iron, manganese, and nickel. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium cobalt oxides. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium nickel manganese cobalt oxides. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium nickel cobalt aluminum oxides. The lithium host material, typically for an anode, can be selected from the group consisting of graphite, lithium metal, lithium titanium oxides, hard carbon, tin/cobalt alloy, or silicon/carbon.

(47) For the dopant of this method, the transition metal can be selected from the group consisting of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, or the transition metal oxide can be selected from the group consisting of oxides of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, or the transition metal salt can be selected from the group consisting of salts of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. The dopant can provide cobalt ions in a crystal structure of the ceramic material.

(48) In this method, the ceramic material can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

(49) In this method, the transition metal ion can be diffused into the crystal structure using gas phase transport from a solid comprising a transition metal, a transition metal oxide or a transition metal salt. The diffusion step can comprise diffusing one or more cobalt ions into the crystal structure using gas phase transport from a powder comprising a cobalt metal, a cobalt oxide or a cobalt salt.

(50) In another embodiment, the invention provides a method for forming a composite electrode for an electrochemical device. In this method, a slurry is cast on a surface to form a layer. The slurry can comprise (i) a lithium host material comprising a lithium metal oxide including a transition metal ion, and (ii) a ceramic material comprising an oxide including lithium, lanthanum, and zirconium, and having a garnet-type or garnet-like crystal structure. The layer is sintered, preferably at a temperature from 400 C. to 1200 C., such that diffusion of the transition metal ion of the lithium metal oxide into the ceramic material provides a transition metal ion dopant in a crystal structure of sintered ceramic material of the electrode.

(51) In this method, the lithium host material, typically for a cathode, can be selected from the group consisting of lithium metal oxides wherein the metal is one or more of aluminum, cobalt, iron, manganese, nickel and vanadium, and lithium-containing phosphates having a general formula LiMPO.sub.4 wherein M is one or more of cobalt, iron, manganese, and nickel. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium cobalt oxides. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium nickel manganese cobalt oxides. The lithium host material, typically for a cathode, can be selected from the group consisting of lithium nickel cobalt aluminum oxides. The lithium host material, typically for an anode, can be selected from the group consisting of graphite, lithium metal, lithium titanium oxides, hard carbon, tin/cobalt alloy, or silicon/carbon.

(52) For the dopant of this method, the transition metal can be selected from the group consisting of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, or the transition metal oxide can be selected from the group consisting of oxides of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof, or the transition metal salt can be selected from the group consisting of salts of Co, Mn, Cr, V, Ti, Mo, Ni, Cu, Zn, W, Bi, Sn, Pb, Cd, Sc, Y, Mg, Ca, Sr, Ba, Fe, and mixtures thereof. The dopant can provide cobalt ions in a crystal structure of the ceramic material.

(53) In this method, the ceramic material can have a formula of Li.sub.wA.sub.xM.sub.2Re.sub.3-yO.sub.z wherein w is 5-7.5, wherein A is selected from B, Al, Ga, In, Zn, Cd, Y, Sc, Mg, Ca, Sr, Ba, Co, Fe, and any combination thereof, wherein x is 0-2, wherein M is selected from Zr, Hf, Nb, Ta, Mo, W, Sn, Ge, Si, Sb, Se, Te, and any combination thereof, wherein Re is selected from lanthanide elements, actinide elements, and any combination thereof, wherein y is 0-0.75, wherein z is 10.875-13.125, and wherein the crystal structure is a garnet-type or garnet-like crystal structure.

(54) In any of the methods for forming a composite electrode, the slurry to be cast may include optional components. For example, the slurry may optionally include one or more sintering aids which melt and form a liquid that can assist in sintering of a cast slurry formulation of the invention via liquid phase sintering. Example sintering aids can be selected from boric acid, boric acid salts, boric acid esters, boron alkoxides phosphoric acid, phosphoric acid salts, phosphate acid esters, silicic acid, silicic acid salts, silanols, silicon alkoxides, aluminum alkoxides and mixtures thereof.

(55) The slurry may optionally include a dispersant. One purpose of the dispersant is to stabilize the slurry and prevent the suspended active battery material particles from settling out. The dispersant may be selected from the group consisting of salts of lithium and a fatty acid. The fatty acid may be selected from lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, and behenic acid.

(56) The slurry may optionally include a plasticizer. The purpose of the plasticizer is to increase the workability of the as-cast tape. Preferably, the plasticizer is a naturally derived plant based oil. The plasticizer may be selected from the group consisting of coconut oil, castor oil, soybean oil, palm kernel oil, almond oil, corn oil, canola oil, rapeseed oil, and mixtures thereof.

(57) The slurry formulation may optionally include a binder. Non-limiting examples of the binder include: poly(methylmethacrylate), poly(vinylacetate), polyvinyl alcohol, polyethyleneoxide, polyvinylpyrrolidone, polyvinyl ether, polyvinylchloride, polyacrylonitrile, polyvinylpyridine, styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyethylene, polypropylene, ethylene-propylene-diene terpolymers (EPDM), cellulose, carboxymethylcellulose, starch, hydroxypropylcellulose, and mixtures thereof. The binder is preferably a non-fluorinated polymeric material.

(58) The slurry may optionally include a solvent is useful in a slurry formulation to dissolve the binder and act as a medium for mixing the other additives. Any suitable solvents may be used for mixing the active battery material particles, dispersant, and binder into a uniform slurry. Suitable solvents may include alkanols (e.g., ethanol), nitriles (e.g., acetonitrile), alkyl carbonates, alkylene carbonates (e.g., propylene carbonate), alkyl acetates, sulfoxides, glycol ethers, ethers, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, or a mixture of any of these solvents.

(59) The slurry formulation may include other additives. For example, the cathode or anode active battery material particles may be mixed with other particles, such as conductive particles. Any conductive material may be used without particular limitation so long as it has suitable conductivity without causing chemical changes in the fabricated battery. Examples of conductive materials include graphite; carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black; conductive fibers such as carbon fibers and metallic fibers; metallic powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.

(60) Any suitable method may be used to mix the slurry components into a uniform slurry. Suitable mixing methods may include sonication, mechanical stirring, physical shaking, vortexing, ball milling, and any other suitable means.

(61) After the uniform slurry is obtained, the formulation is cast on a substrate surface to form a cast tape layer. The substrate may include any stable and conductive metals suitable as a current collector for the battery. A suitable metallic substrate may include aluminum, copper, silver, iron, gold, nickel, cobalt, titanium, molybdenum, steel, zirconium, tantalum, and stainless steel. In one embodiment, the metal substrate is aluminum.

(62) The slurry layer cast on the surface may have a thickness in the range of a few micrometers to a few centimeters. In one embodiment, the thickness of the cast slurry layer is in the range of 10 micrometers to 150 micrometers, preferably 10 micrometers to 100 micrometers. After the slurry is cast on the substrate surface to form a tape, the green tape can be dried and sintered to a composite electrode having a thickness in the range of 10 micrometers to 150 micrometers, preferably 20 micrometers to 100 micrometers, more preferably 50 micrometers to 100 micrometers. Optionally, multiple layers can be cast on top of one another. For example, the anode can be cast first on the metal substrate, followed by casting the solid electrolyte on the anode, and finally casting the cathode on the electrolyte. Alternatively, the cathode can be cast first on the metal substrate, followed by the solid electrolyte, and finally the anode. The multi-layer green tape can be dried and sintered to achieve the necessary electrochemical properties.

(63) Thus, the invention provides electrochemical devices, such as lithium ion battery composite electrodes, and solid-state lithium ion batteries including these composite electrodes and solid-state electrolytes. The composite electrodes include one or more separate phases within the electrode that provide electronic and ionic conduction pathways in the electrode active material phase. The solid state electrochemical devices have applications in electric vehicles, consumer electronics, medical devices, oil/gas, military, and aerospace.

(64) Although the invention has been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the embodiments contained herein.