Lithium ion conductive inorganic substance
To provide a lithium ion conductive inorganic substance that makes it possible to further enhance the charge-discharge voltage of batteries and to further improve the charge-discharge properties of batteries. The lithium ion conductive inorganic substance includes a ZrO 2 component from 2.6% to 52.0% by mass on an oxide basis. The lithium ion conductive inorganic substance is preferably used for lithium ion secondary batteries that have a positive electrode layer, a negative electrode layer, and a solid electrolyte layer intervening between the positive electrode layer and the negative electrode layer.
1. A lithium ion conductive inorganic substance, comprising:
a ZrO 2 component from 10.0% to 52.0% by mass on an oxide basis; and
a crystalline phase of Li 1+x+z M x A 2−x P 3−z Si z O 12 , wherein 0<X≦1, 0<Z<1, M: at least one selected from Al, Sc, Y, Ga, and La, and A: at least one selected from Ti, Zr, Ge, and Sn.
2. The lithium ion conductive inorganic substance according to claim 1 , wherein the lithium ion conductive inorganic substance is a glass ceramic.
3. The lithium ion conductive inorganic substance according to claim 1 , wherein the lithium ion conductive inorganic substance is a ceramic.
4. The lithium ion conductive inorganic substance according claim 1 , further comprising a Li 2 O component from 3.0% to 9.5%, a P 2 O 5 component from 24% to 55%, an AO 2 component from 21% to 51%, and a M 2 O 3 component greater than 0% and no greater than 24% by mass on an oxide basis (A: at least one selected from Zr, Ti, Ge, and Sn, and M: at least one selected from Al, Y, Sc, Ga, and La).
5. The lithium ion conductive inorganic substance according claim 1 , wherein the content of an SiO 2 component is no greater than 18% by mass on an oxide basis.
6. The lithium ion conductive inorganic substance according claim 1 , wherein a mass ratio on an oxide basis of Y 2 O 3 /(ZrO 2 +Y 2 O 3 ) from 0.001 to 0.14 or Sc 2 O 3 /(ZrO 2 +Sc 2 O 3 ) from 0.001 to 0.10 is satisfied.
7. The lithium ion conductive inorganic substance according claim 1 , wherein a lithium ion conductivity at 25° C. is no less than 1.0×10 −7 S·cm −1 .
8. The lithium ion conductive inorganic substance according claim 1 , wherein a potential with respect to Li at 25° C. is no less than 0.3 V and no greater than 1.5 V and a current density of a reduction current is less than 10 μA/cm 2 .
9. A lithium ion secondary battery, comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer that intervenes between the positive electrode layer and the negative electrode layer, and that comprises a solid electrolyte formed from the lithium ion conductive inorganic substance according to claim 1 .
10. A solid electrolyte used for primary batteries or secondary batteries, having a thickness from 0.5 μm to 1000 μm and comprising the lithium ion conductive inorganic substance according claim 1 .
11. The lithium ion conductive inorganic substance according to claim 1 , wherein the content of an ZrO 2 component is from 10.4 to 52.0% by mass on an oxide basis.