Stacked battery
A main object of the present disclosure is to provide a stacked battery in which an unevenness of short circuit resistance among a plurality of cells is suppressed. The present disclosure achieves the object by providing a stacked battery comprising: a plurality of cells in a thickness direction, wherein the plurality of cells are electrically connected in parallel; each of the plurality of cells includes a cathode current collector, a cathode active material layer, a solid electrolyte layer, an anode active material layer, and an anode current collector, in this order; the stacked battery includes a surface-side cell that is located on a surface side of the stacked battery, and a center-side cell that is located on a center side rather than the surface-side cell; and a contact resistance between the cathode current collector and the anode current collector in the surface-side cell is more than a contact resistance between the cathode current collector and the anode current collector in the center-side cell.
1. A stacked battery comprising:
a plurality of cells in a thickness direction, wherein
the plurality of cells are electrically connected in parallel;
each of the plurality of cells includes a cathode current collector, a cathode active material layer, a solid electrolyte layer, an anode active material layer, and an anode current collector, in this order;
the stacked battery includes a surface-side cell that is located on a surface side of the stacked battery, and a center-side cell that is located on a center side rather than the surface-side cell;
a contact resistance between the cathode current collector and the anode current collector in the surface-side cell is more than a contact resistance between the cathode current collector and the anode current collector in the center-side cell, wherein the contact resistance pertains to a physical contact between the anode current collector and the cathode current collector;
the total cell number included in the stacked battery is 3 or more;
when the contact resistance between the cathode current collector and the anode current collector in the surface-side cell is R c1 , and the contact resistance between the cathode current collector and the anode current collector in the center-side cell is R c2 , R c1 /R c2 under pressure of 100 MPa is in a range of 1.5-10,000;
the solid electrolyte layer includes an inorganic solid electrolyte material as a solid electrolyte material; and
the surface-side cell and the center-side cell satisfying at least one of the following conditions:
i) a material for the cathode current collector in the surface-side cell is different from a material for the cathode current collector in the center-side cell; and
ii) a material for the anode current collector in the surface-side cell is different from the material for the anode current collector in the center-side cell.
2. The stacked battery according to claim 1 , wherein at least one of the cathode current collector and the anode current collector in the surface-side cell includes, on a surface thereof, an oxide layer.
3. The stacked battery according to claim 1 , wherein the cathode current collector in the surface-side cell includes, on a surface thereof, a first coating layer containing a carbon material, and
the cathode current collector in the center-side cell includes, on a surface thereof, a second coating layer containing a carbon material.
4. The stacked battery according to claim 3 , wherein a content of the carbon material in the first coating layer is less than a content of the carbon material in the second coating layer.
5. The stacked battery according to claim 3 , wherein a thickness of the first coating layer is more than a thickness of the second coating layer.
6. The stacked battery according to claim 3 , wherein, when a proportion of a resistance R 200 at 200° C. with respect to a resistance R 25 at 25° C. is R 200 /R 25 ,
the R 200 /R 25 value of the first coating layer is more than the R 200 /R 25 value of the second coating layer.
7. The stacked battery according to claim 1 , wherein the anode current collector in the surface-side cell includes, on a surface thereof, a third coating layer containing a carbon material, and
the anode current collector in the center-side cell includes, on a surface thereof, a fourth coating layer containing a carbon material.
8. The stacked battery according to claim 7 , wherein a content of the carbon material in the third coating layer is less than a content of the carbon material in the fourth coating layer.
9. The stacked battery according to claim 7 , wherein a thickness of the third coating layer is more than a thickness of the fourth coating layer.
10. The stacked battery according to claim 7 , wherein, when a proportion of a resistance R 200 at 200° C. with respect to a resistance R 25 at 25° C. is R 200 /R 25 ,
the R 200 /R 25 value of the third coating layer is more than the R 200 /R 25 value of the fourth coating layer.
11. The stacked battery according to claim 1 , wherein:
one of the cathode current collector and the anode current collector in the surface-side cell includes, on a surface thereof, a coating layer containing a carbon material, and another does not include, on a surface thereof, a coating layer containing a carbon material; and
one of the cathode current collector and the anode current collector in the center-side cell includes, on a surface thereof, a coating layer containing a carbon material, and another does not include, on a surface thereof, a coating layer containing a carbon material in reverse to the surface-side cell.
12. The stacked battery according to claim 1 , wherein, when each of the plurality of cells is numbered as 1 st cell to N th cell, in which N≥3, in order along the thickness direction of the stacked battery,
the surface-side cell is a cell that belongs to a cell region A including 1 st cell to (N/3) th cell.
13. The stacked battery according to claim 12 , wherein the center-side cell is a cell that belongs to a cell region B including ((N/3)+1) th cell to (2N/3) th cell.
14. The stacked battery according to claim 13 , wherein an average value of the contact resistance in the cell region A is more than an average value of the contact resistance in the cell region B.
15. The stacked battery according to claim 1 , wherein, when each of the plurality of cells is numbered as 1 st cell to N th cell, in which N≥60, in order along the thickness direction of the stacked battery,
the surface-side cell is a cell that belongs to a cell region C including 1 st cell to 20 th cell.
16. The stacked battery according to claim 15 , wherein the center-side cell is a cell that belongs to a cell region D including 21 st cell to 40 th cell.
17. The stacked battery according to claim 16 , wherein an average value of the contact resistance in the cell region C is more than an average value of the contact resistance in the cell region D.
18. The stacked battery according to claim 1 , wherein the anode active material layer includes Si or a Si alloy as an anode active material.
19. The stacked battery according to claim 1 , wherein the value of R c1 under pressure of 100 MPa is 0.037 Ω·cm 2 or more and 0.277 Ω·cm 2 or less.
20. The stacked battery according to claim 1 , wherein, in a state in which a nail penetration test has been conducted, the contact resistance between the cathode current collector and the anode current collector in the surface-side cell is more than the contact resistance between the cathode current collector and the anode current collector in the center-side cell.