All solid lithium ion secondary battery and a solid electrolyte therefor
An all solid type lithium ion secondary battery which has high heat resistance and can be used over a broad temperature range, has a high battery capacity and an excellent charging-discharging characteristic, and can be used stably for a long period of time includes an inorganic substance including a lithium ion conductive crystalline and is substantially free of an organic substance and an electrolytic solution. The inorganic substance comprising a lithium ion conductive crystalline preferably is lithium ion conductive glass-ceramics.
1. A solid electrolyte comprising sintered inorganic substance powder comprising a lithium ion conductive crystalline said sintered inorganic substance powder being in an amount within a range from 50 mass % to 98 mass %,
wherein said solid electrolyte is substantially free of an organic substance and an electrolytic solution, and
said solid electrolyte has a thickness of 25 μm or over.
2. A solid electrolyte as defined in claim 1 wherein the inorganic substance powder comprising a lithium ion conductive crystalline is substantially free of a pore or a crystal grain boundary which obstructs ion conduction.
3. A solid electrolyte as defined in claim 1 wherein the inorganic substance powder comprising a lithium ion conductive crystalline is lithium ion conductive glass-ceramics.
4. A solid electrolyte as defined in claim 1 comprising an inorganic substance powder comprising a lithium ion conductive crystalline and an inorganic substance comprising Li.
5. A solid electrolyte as defined in claim 4 wherein the inorganic substance powder comprising a lithium ion conductive crystalline has ion conductivity of 10 −4 Scm −1 or over, has an average particle diameter of 9 μm or below.
6. A solid electrolyte as defined in claim 3 wherein the ion conductive glass-ceramics are in the form of a thin plate.
7. A solid electrolyte as defined in claim 1 having ion conductivity which is 10 −5 Scm −1 or over.
8. A solid electrolyte as defined in claim 1 wherein the inorganic substance powder comprising a lithium ion conductive crystalline has a predominant crystal phase of Li 1+x+y Al x Ti 2−x Si y P 3−y O 12 where 0≦x≦1 and 0≦y≦1.
9. A solid electrolyte as defined in claim 1 wherein the inorganic powder substance comprising a lithium ion conductive crystalline comprises, in mol %;
Li 2 O
12-18%
Al 2 O 3 + Ga 2 O 3
5-10%
TiO 2 + GeO 2
35-45%
SiO 2
1-10%
and
P 2 O 5
30-40%.
10. A solid electrolyte as defined in claim 1 wherein the inorganic substance powder comprising a lithium ion conductive crystalline comprises, in mass %;
Li 2 O
3-10%
Al 2 O 3 + Ga 2 O 3
5-20%
TiO 2 + GeO 2
25-40%
SiO 2
0.5-8%
and
P 2 O 5
40-55%.
11. A lithium ion secondary battery comprising a solid electrolyte as defined in claim 1 .
12. A lithium ion secondary battery as defined in claim 11 comprising an inorganic substance comprising a lithium ion conductive crystalline in a positive electrode and/or a negative electrode.
13. A lithium ion secondary battery as defined in claim 12 wherein the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode is substantially free of a pore or a crystal grain boundary which obstructs ion conduction.
14. A lithium ion secondary battery as defined in claim 12 wherein the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode is a lithium ion conductive glass-ceramics.
15. A lithium ion secondary battery as defined in claim 12 wherein an average particle diameter of the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode is ⅕ or below of an average particle diameter of an active material of the positive electrode and/or the negative electrode comprising an inorganic substance comprising a lithium ion conductive crystalline.
16. A lithium ion secondary battery as defined in claim 12 wherein an amount of the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode is 2-35 mass % of an active material of the positive electrode and/or the negative electrode.
17. A lithium ion secondary battery as defined in claim 12 wherein the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode comprises, in mol %;
Li 2 O
12-18%
Al 2 O 3 + Ga 2 O 3
5-10%
TiO 2 + GeO 2
35-45%
SiO 2
1-10%
and
P 2 O 5
30-40%.
18. A lithium ion secondary battery as defined in claim 12 wherein the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode comprises, in mass %;
Li 2 O
3-10%
Al 2 O 3 + Ga 2 O 3
5-20%
TiO 2 + GeO 2
25-40%
SiO 2
0.5-8%
and
P 2 O 5
40-55%.
19. A lithium ion secondary battery as defined in claim 12 wherein the inorganic substance comprising a lithium ion conductive crystalline contained in the positive electrode and/or the negative electrode has a predominant crystal phase of Li 1+x+y Al x Ti 2−x Si y P 3−y O 12 where 0≦x≦1 and 0≦y≦1.
20. A lithium ion secondary battery as defined in claim 12 which comprises, in the positive electrode and/or the negative electrode, the same inorganic substance as the inorganic substance comprising a lithium ion conductive crystalline contained in the solid electrolyte.