Ionic conductor and secondary battery

Abstract

An ionic conductor is provided, wherein a composition formula thereof is Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(GeO.sub.4).sub.x, wherein x is a range of 0<x≦2.0.

Claims

1. An ionic conductor, wherein a composition formula thereof is Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(GeO.sub.4).sub.x, wherein x is a range of 0<x≦2.0.

2. An ionic conductor, wherein a composition formula thereof is Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(SiO.sub.4).sub.x, wherein x is a range of 0<x≦2.0.

3. An ionic conductor, wherein a composition formula thereof is Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(SiO.sub.4).sub.x/2(GeO.sub.4).sub.x/2, wherein x is a range of 0<x≦2.0.

4. An ionic conductor, wherein a composition formula thereof is Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(MO.sub.4).sub.x, wherein M is selected from a group consisting of C, Si, Ge, Sn, Pb, and any combination thereof, and wherein x is a range of 0<x≦2.0.

5. The ionic conductor as claimed in claim 1, wherein the ionic conductor has a crystal structure of space group P-3c1.

6. The ionic conductor as claimed in claim 2, wherein the ionic conductor has a crystal structure of space group P-3c1.

7. The ionic conductor as claimed in claim 3, wherein the ionic conductor has a crystal structure of space group P-3c1.

8. The ionic conductor as claimed in claim 4, wherein the ionic conductor has a crystal structure of space group P-3c1.

9. A secondary battery, comprising: a solid electrolyte formed of the ionic conductor as claimed in claim 1; an electrode formed on one face of the solid electrolyte; and an electrode formed on the other face of the solid electrolyte.

10. A secondary battery, comprising: a solid electrolyte formed of the ionic conductor as claimed in claim 2; an electrode formed on one face of the solid electrolyte; and an electrode formed on the other face of the solid electrolyte.

11. A secondary battery, comprising: a solid electrolyte formed of the ionic conductor as claimed in claim 3; an electrode formed on one face of the solid electrolyte; and an electrode formed on the other face of the solid electrolyte.

12. A secondary battery, comprising: a solid electrolyte formed of the ionic conductor as claimed in claim 4; an electrode formed on one face of the solid electrolyte; and an electrode formed on the other face of the solid electrolyte.

13. The secondary battery as claimed in claim 9, wherein the electrode formed on one face is formed of Li.sub.9V.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2.

14. The secondary battery as claimed in claim 10, wherein the electrode formed on one face is formed of Li.sub.9V.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2.

15. The secondary battery as claimed in claim 11, wherein the electrode formed on one face is formed of Li.sub.9V.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2.

16. The secondary battery as claimed in claim 12, wherein the electrode formed on one face is formed of Li.sub.9V.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2.

17. The secondary battery as claimed in claim 9, wherein the ionic conductor and the electrode formed on one face have an identical crystal structure.

18. The secondary battery as claimed in claim 10, wherein the ionic conductor and the electrode formed on one face have an identical crystal structure.

19. The secondary battery as claimed in claim 11, wherein the ionic conductor and the electrode formed on one face have an identical crystal structure.

20. The secondary battery as claimed in claim 12, wherein the ionic conductor and the electrode formed on one face have an identical crystal structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural diagram of LVPP that is used as a positive electrode material.

(2) FIG. 2 is a structural diagram of an ionic conductor with a NASICON structure.

(3) FIG. 3 is a structural diagram of an ionic conductor in a first embodiment.

(4) FIG. 4 is a structural diagram of a secondary battery in a second embodiment.

(5) FIG. 5 is a correlation diagram between composition ratios and electrical conductivities of ionic conductors in Practical Examples 1-5.

(6) FIG. 6 is a diagram that illustrates results of X-ray diffraction for ionic conductors in Practical Examples 1-5.

(7) FIG. 7 is a correlation diagram between composition ratios and electrical conductivities of ionic conductors in Practical Examples 6-10.

(8) FIG. 8 is a diagram that illustrates results of X-ray diffraction for ionic conductors in Practical Examples 6-10.

(9) FIG. 9 is a correlation diagram between composition ratios and electrical conductivities of ionic conductors in Practical Examples 11-13.

(10) FIG. 10 is a diagram that illustrates results of X-ray diffraction for ionic conductors in Practical Examples 11-13.

DESCRIPTION OF EMBODIMENTS

(11) Embodiments for implementing the invention will be described below. Here, an identical letter or numeral will be attached to an identical member or the like and a description(s) thereof will be omitted.

A First Embodiment

(12) As described previously, Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 utilizes an oxidation reduction reaction of V.sup.3+.fwdarw.V.sup.5+, and has a theoretical capacitance that is 1.2 times as large as that of LiCoO.sub.2. Because this Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 has a crystal structure that is different from that of LiCoO.sub.2, an ionic conductor that is a solid electrolyte with a high matching property with Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 has not existed at present. Therefore, even though a secondary battery is fabricated by combining a known ionic conductor with Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 as an electrostatic electrode, it is not possible to derive an effect of using Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 sufficiently at present. Hence, an ionic conductor is desired wherein it is possible to derive an effect of using Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 sufficiently.

(13) Meanwhile, the inventor executed a study for a preferable ionic conductor in a case where Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 was used as a positive electrode material, and as a result, conceived and reached an idea that an ionic conductor with a crystal structure similar to that of Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 provided a high matching property. As a result of synthesis of an ionic conductor that was tried based on this idea, it was possible to obtain an ionic conductor that had a crystal structure similar to that of Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2, namely, in a space group of P-3c1 (165). The present embodiment is based on such a process, and it is possible to improve a characteristic of a secondary battery more than a conventional one by using Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 as a positive electrode material and using an ionic conductor in the present embodiment as a solid electrolyte.

(14) (An Ionic Conductor)

(15) First, Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 will be described that is a positive electrode material of a secondary battery. As illustrated in FIG. 1, Li.sub.2V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 is formed of Li (lithium), VO.sub.6, P.sub.2O.sub.7, and PO.sub.4. Li.sub.2V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 is such that a space group thereof is P-3c1 (165) and there is an anisotropy in a direction of a c-axis that is a diffusion pathway. Here, Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 may be described as an LVPP in the present embodiment.

(16) On the other hand, FIG. 2 illustrates Li.sub.1.5Al.sub.0.5Ge.sub.1.5 (PO.sub.4).sub.3 that is a solid electrolyte with a NASICON structure that is commonly used as a solid electrolyte. Li.sub.1.5Al.sub.0.5Ge.sub.1.5(PO.sub.4).sub.3 is such that a space group thereof is R-3cH (167), and a crystal structure thereof is different from that of Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2, and further, a diffusion pathway of lithium is also different from that of Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 and is isotropic. In this Li.sub.1.5Al.sub.0.5Ge.sub.1.5(PO.sub.4).sub.3, a migration distance of lithium from a solid electrolyte to an outermost surface of a positive electrode is 12.769 angstrom.

(17) Next, an ionic conductor for forming a solid electrolyte in the present embodiment will be described. An ionic conductor in the present embodiment is Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(GeO.sub.4).sub.x, wherein a part of (PO.sub.4) in Li.sub.2V.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2 is replaced by (GeO.sub.4). Herein, x is a range of 0<x≦2.0. Thus, a part of (PO.sub.4) is replaced by (GeO.sub.4), so that Li is increased accordingly and a carrier is also increased. Here, Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 may be described as LAPP and Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (GeO.sub.4).sub.x may be described as an LAPPG in the present embodiment.

(18) FIG. 3 illustrates a structure of Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4)(GeO.sub.4) that is an ionic conductor in the present embodiment. This Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4)(GeO.sub.4) is formed of Li (lithium), AlO.sub.6, P.sub.2O.sub.7, PO.sub.4, and GeO.sub.4. Li.sub.10Al.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4)(GeO.sub.4) in the preset embodiment has a crystal structure similar to that of Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 that is a positive electrode material, wherein a space group is P-3c1 (165) and there is an anisotropy in a direction of a c-axis that is a diffusion pathway of lithium. That is, a space group is had that is a crystal structure identical to that of Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 that is a positive electrode material and an anisotropy is had that is similar to a diffusion pathway of lithium. Therefore, a matching property with Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 that is a positive electrode material is high. Furthermore, a migration distance of lithium from a solid electrolyte of this ionic conductor to an outermost surface of a positive electrode is 6.797 angstrom that is less than that of LAGP, so that it is possible to reduce a migration resistance between lithium sites.

(19) Furthermore, an ionic conductor in the present embodiment may be Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(SiO.sub.4).sub.x wherein a part of (PO.sub.4) is replaced by (SiO.sub.4), other than Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(GeO.sub.4).sub.x as described above. Furthermore, Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (SiO.sub.4).sub.x/2 (GeO.sub.4).sub.x/2 may be provided wherein a part of (PO.sub.4) is replaced by (SiO.sub.4) and (GeO.sub.4). Here, in the present embodiment, Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (SiO.sub.4).sub.x may be described as an LAPPS and Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x (SiO.sub.4).sub.x/2 (GeO.sub.4).sub.x/2 may be described as an LAPPSG.

(20) Moreover, it is considered that it is possible for an element such as C, Sn, or Pb to obtain a similar effect, other than Ge in (GeO.sub.4) and Si in (SiO.sub.4). That is, an ionic conductor in the present embodiment may be such that a composition formula thereof is Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (MO.sub.4).sub.x, wherein M is formed of one or two or more elements selected from C, Si, Ge, Sn, and Pb.

(21) (a Manufacturing Method for an Ionic Conductor)

(22) Next, a manufacturing method for Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4)(GeO.sub.4) will be described that is an ionic conductor in the present embodiment.

(23) First, lithium phosphate (Li.sub.3PO.sub.4), aluminum oxide (Al.sub.2O.sub.3), germanium oxide (GeO2), diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) are mixed by using a mortar made of agate. Then, a mixture thereof is put into a platinum crucible and heated to 900° C., subsequently, is slowly cooled to 850° C. at 50° C./H, and subsequently, is slowly cooled to 600° C. at 2° C./H, and subsequently, slow cooling to a room temperature is executed at 200° C./H.

(24) Here, weighed values of lithium phosphate (Li.sub.3PO.sub.4), aluminum oxide (Al.sub.2O.sub.3), germanium oxide (GeO.sub.2), diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) are 4.0878 g, 1.6922 g, 11.5767 g, and 10.2285 g, respectively. Thus, it is possible to fabricate Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4)(GeO.sub.4) that is an ionic conductor in the present embodiment.

A Second Embodiment

(25) Next, a secondary battery in a second embodiment will be described. A secondary battery in the present embodiment is such that an ionic conductor in the first embodiment is used for a solid electrolyte. Specifically, a secondary battery in the present embodiment is of a structure in such a manner that an electrode 31 that is a positive electrode is provided on one face of a solid electrolyte 30 formed of an ionic conductor in the first embodiment and an electrode 32 that is a negative electrode is provided on the other face thereof, as illustrated in FIG. 4. Here, Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 is used for the electrode 31 that is a positive electrode and Li is used for the electrode 32 that is a negative electrode.

(26) According to a disclosed ionic conductor and secondary battery, it is possible to provide a high matching property with Li.sub.9V.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 that is a positive electrode material and reduce an internal resistance thereof, and hence, it is possible to improve a characteristic of a secondary battery.

(27) Next, practical examples of an ionic conductor in the first embodiment will be described.

Practical Example 1

(28) For Practical Example 1, an LAPPG that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (GeO.sub.4).sub.x wherein x was 0.25, namely, Li.sub.9.25Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.75(GeO.sub.4).sub.0.25 was fabricated.

(29) Specifically, first, 1.9708 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8818 g of aluminum oxide (Al.sub.2O.sub.3), 0.1510 g of germanium oxide (GeO.sub.2), and 5.9010 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 1 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 3.4×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 2

(30) For Practical Example 2, an LAPPG that was Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(GeO.sub.4).sub.x wherein x was 0.5, namely, Li.sub.9.5Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.5(GeO.sub.4).sub.0.5 was fabricated.

(31) Specifically, first, 1.9960 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8697 g of aluminum oxide (Al.sub.2O.sub.3), 0.2979 g of germanium oxide (GeO.sub.2), and 5.6323 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 2 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 2.2×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 3

(32) For Practical Example 3, an LAPPG that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x(GeO.sub.4).sub.x wherein x was 1.0, namely, Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.0(GeO.sub.4).sub.1.0 was fabricated.

(33) Specifically, first, 2.0447 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8465 g of aluminum oxide (Al.sub.2O.sub.3), 0.5793 g of germanium oxide (GeO.sub.2), and 5.1142 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 3 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 1.7×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 4

(34) For Practical Example 4, an LAPPG that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x(GeO.sub.4).sub.x wherein x was 1.5, namely, Li.sub.10.5Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.0.5(GeO.sub.4).sub.1.5 was fabricated.

(35) Specifically, first, 2.0885 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8230 g of aluminum oxide (Al.sub.2O.sub.3), 0.8454 g of germanium oxide (GeO.sub.2), and 4.6260 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 4 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 1.5×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 5

(36) For Practical Example 5, Ll.sub.11Al.sub.3 (P.sub.2O.sub.7).sub.3 (GeO.sub.4).sub.2.0 that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (GeO.sub.4).sub.x wherein x was 2.0 was fabricated.

(37) Specifically, first, 2.1338 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8020 g of aluminum oxide (Al.sub.2O.sub.3), 1.0987 g of germanium oxide (GeO.sub.2), and 4.1585 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 5 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 1.0×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 6

(38) For Practical Example 6, an LAPPS that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (SiO.sub.4).sub.x wherein x was 0.25, namely, Li.sub.9.25Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.75(SiO.sub.4).sub.0.25 was fabricated.

(39) Specifically, first, 1.9970 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8935 g of aluminum oxide (Al.sub.2O.sub.3), 0.0891 g of silicon oxide (SiO.sub.2), and 5.9768 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 6 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 1.5×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 7

(40) For Practical Example 7, an LAPPS that was Li.sub.9+xAl.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2−x(SiO.sub.4).sub.x wherein x was 0.5, namely, Li.sub.9.5Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.5(SiO.sub.4).sub.0.5 was fabricated.

(41) Specifically, first, 2.0483 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8920 g of aluminum oxide (Al.sub.2O.sub.3), 0.1763 g of silicon oxide (SiO.sub.2), and 5.7787 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 7 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 2.4×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 8

(42) For Practical Example 8, an LAPPS that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x(SiO.sub.4) wherein x was 1.0, namely, Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.0(SiO.sub.4).sub.1.0 was fabricated.

(43) Specifically, first, 2.1500 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8895 g of aluminum oxide (Al.sub.2O.sub.3), 0.3498 g of silicon oxide (SiO.sub.2), and 5.3805 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, weighed lithium carbonate, aluminum oxide, silicon oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, tentative baking thereof was executed under argon atmosphere at a temperature of 300° C. for 5 hours. Then, tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, main baking thereof was executed under argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 8 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 3.7×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 9

(44) For Practical Example 9, an LAPPS that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x(SiO.sub.4).sub.x wherein x was 1.5, namely, Li.sub.10.5Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.0.5(SiO.sub.4).sub.1.5 was fabricated.

(45) Specifically, first, 2.2521 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8872 g of aluminum oxide (Al.sub.2O.sub.3), 0.5238 g of silicon oxide (SiO.sub.2), and 4.9853 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 9 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 4.1×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 10

(46) For Practical Example 10, Li.sub.11Al.sub.3 (P.sub.2O.sub.7).sub.3(SiO.sub.4).sub.2.0 that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x(SiO.sub.4).sub.x wherein x was 2.0 was fabricated.

(47) Specifically, first, 2.5470 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8855 g of aluminum oxide (Al.sub.2O.sub.3), 0.6954 g of silicon oxide (SiO.sub.2), and 4.5880 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmO, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 10 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 2.6×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 11

(48) For Practical Example 11, an LAPPSG that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (SiO.sub.4).sub.x/2 (GeO.sub.4).sub.x/2 wherein x was 0.5, namely, Li.sub.9.5Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.5(SiO.sub.4).sub.0.25(GeO.sub.4).sub.0.25 was fabricated.

(49) Specifically, first, 2.2290 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8807 g of aluminum oxide (Al.sub.2O.sub.3), 0.0877 g of silicon oxide (SiO.sub.2), 0.1509 g of germanium oxide (GeO.sub.2), and 5.7018 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 11 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 1.5×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 12

(50) For Practical Example 12, an LAPPSG that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (SiO.sub.4).sub.x/2 (GeO.sub.4).sub.x/2 wherein x was 1.0, namely, Li.sub.10Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.1.0(SiO.sub.4).sub.0.5(GeO.sub.4).sub.0.5 was fabricated.

(51) Specifically, first, 2.0957 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8670 g of aluminum oxide (Al.sub.2O.sub.3), 0.1720 g of silicon oxide (SiO.sub.2), 0.2980 g of germanium oxide (GeO.sub.2), and 5.2437 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours.

(52) Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 12 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 3.5×10.sup.−7 S.Math.cm.sup.−1.

Practical Example 13

(53) For Practical Example 13, Li.sub.11Al.sub.3 (P.sub.2O.sub.7).sub.3 (SiO.sub.4).sub.1.0 (GeO.sub.4).sub.1.0 that was Li.sub.9+xAl.sub.3 (P.sub.2O.sub.7).sub.3 (PO.sub.4).sub.2−x (SiO.sub.4).sub.x/2 (GeO.sub.4).sub.x/2 wherein x was 2.0 was fabricated.

(54) Specifically, first, 2.2389 g of lithium carbonate (Li.sub.2CO.sub.3), 0.8429 g of aluminum oxide (Al.sub.2O.sub.3), 0.3300 g of silicon oxide (SiO.sub.2), 0.5733 g of germanium oxide (GeO.sub.2), and 4.3653 g of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4) were weighed. Then, the weighed lithium carbonate, aluminum oxide, silicon oxide, germanium oxide, and diammonium hydrogen phosphate were mixed by a ball mill at 200 rpm for 3 hours, and subsequently, a tentative baking thereof was executed under an argon atmosphere at a temperature of 300° C. for 5 hours. Then, the tentatively baked one was milled by a ball mill at 300 rpm for 3 hours, pelleting thereof was executed by using a die with 10 mmφ, and subsequently, a main baking thereof was executed under an argon atmosphere at a temperature of 750° C. for 10 hours, so that an ionic conductor in Practical Example 13 was fabricated. As an electrical conductivity of a fabricated ionic conductor was measured, the electrical conductivity was 1.4×10.sup.−7 S.Math.cm.sup.−1.

(55) The electrical conductivities of the ionic conductors in Practical Examples 1-5 are illustrated in FIG. 5 and Table 1 and results of X-ray diffraction thereof are illustrated in FIG. 6. Furthermore, the electrical conductivities of the ionic conductors in Practical Examples 6-10 are illustrated in FIG. 7 and Table 2 and results of X-ray diffraction thereof are illustrated in FIG. 8. Furthermore, the electrical conductivities of the ionic conductors in Practical Examples 11-13 are illustrated in FIG. 9 and Table 3 and results of X-ray diffraction thereof are illustrated in FIG. 10.

(56) TABLE-US-00001 TABLE 1 Electrical conductivity x [S .Math. cm.sup.−1] Li.sub.9Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 0.0 1.3 × 10.sup.−8 Practical Example 1 0.25 3.4 × 10.sup.−7 Practical Example 2 0.5 2.2 × 10.sup.−7 Practical Example 3 1.0 1.7 × 10.sup.−7 Practical Example 4 1.5 1.5 × 10.sup.−7 Practical Example 5 2.0 1.0 × 10.sup.−7

(57) TABLE-US-00002 TABLE 2 Electrical conductivity x [S .Math. cm.sup.−1] Li.sub.9Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 0.0 1.3 × 10.sup.−8 Practical Example 6 0.25 1.5 × 10.sup.−7 Practical Example 7 0.5 2.4 × 10.sup.−7 Practical Example 8 1.0 3.7 × 10.sup.−7 Practical Example 9 1.5 4.1 × 10.sup.−7 Practical Example 10 2.0 2.6 × 10.sup.−7

(58) TABLE-US-00003 TABLE 3 Electrical conductivity x [S .Math. cm.sup.−1] Li.sub.9Al.sub.3(P.sub.2O.sub.7).sub.3(PO.sub.4).sub.2 0.0 1.3 × 10.sup.−8 Practical Example 11 0.5 1.5 × 10.sup.−7 Practical Example 12 1.0 3.5 × 10.sup.−7 Practical Example 13 2.0 1.4 × 10.sup.−7

(59) Although an embodiment has been described in detail above, limitation to a particular embodiment is not provided and a variety of alterations and modifications are possible within a scope recited in what is claimed.

(60) All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.