Secondary battery using alkaline earth metal ion moving during charge and discharge
A secondary battery includes: a first electrode; a second electrode; a first solid electrolyte covering the first electrode, the first solid electrolyte containing an alkaline earth metal; and a liquid electrolyte filling the space between the first electrode and the second electrode, the liquid electrolyte containing a non-aqueous solvent and a salt of the alkaline earth metal dissolved in the non-aqueous solvent.
1. A secondary battery comprising:
a first electrode;
a second electrode;
a first solid electrolyte covering the first electrode, the first solid electrolyte containing an alkaline earth metal; and
a liquid electrolyte filling a space between the first electrode and the second electrode, the liquid electrolyte containing a non-aqueous solvent and a salt of the alkaline earth metal dissolved in the non-aqueous solvent,
wherein the first solid electrolyte contains a compound represented by Mg x Zr y SiO z ,
where
0<x<2,
0<y<2,
and 3<z<6.
2. The secondary battery according to claim 1 , wherein
the first solid electrolyte further contains a polyanion composed of:
at least one selected from the group consisting of oxygen and nitrogen; and
at least one selected from the group consisting of phosphorus and silicon.
3. The secondary battery according to claim 1 , wherein
the first solid electrolyte is amorphous.
4. The secondary battery according to claim 1 , wherein
the first electrode is a positive electrode, and
the second electrode is a negative electrode.
5. The secondary battery according to claim 4 , wherein
the positive electrode includes:
a positive electrode collector; and
a positive electrode active material layer disposed on the positive electrode collector, the positive electrode active material layer including a plurality of positive electrode active material particles, and
the first solid electrolyte is formed as a layer disposed on the positive electrode active material layer, the positive electrode active material particles being collectively covered with the layer.
6. The secondary battery according to claim 5 , wherein
the positive electrode active material layer has an irregular surface defined by the positive electrode active material particles, and
the first solid electrolyte is formed along the irregular surface.
7. The secondary battery according to claim 4 , wherein
the positive electrode includes:
a positive electrode collector; and
a positive electrode active material layer disposed on the positive electrode collector, the positive electrode active material layer including a plurality of positive electrode active material particles, and
the first solid electrolyte is formed as a plurality of coats covering the respective positive electrode active material particles.
8. The secondary battery according to claim 4 , further comprising:
a second solid electrolyte covering the negative electrode and containing the alkaline earth metal.
9. The secondary battery according to claim 1 , wherein
the first electrode is a negative electrode, and
the second electrode is a positive electrode.
10. The secondary battery according to claim 9 , wherein
the negative electrode includes:
a negative electrode collector; and
a negative electrode active material layer disposed on the negative electrode collector, the negative electrode active material layer including a plurality of negative electrode active material particles, and
the first solid electrolyte is formed as a layer disposed on the negative electrode active material layer, the negative electrode active material particles being collectively covered with the layer.
11. The secondary electrode according to claim 10 , wherein
the negative electrode active material layer has an irregular surface defined by the negative electrode active material particles; and
the first solid electrolyte is formed along the irregular surface.
12. The secondary battery according to claim 9 , wherein
the negative electrode includes:
a negative electrode collector; and
a negative electrode active material layer disposed on the negative electrode collector, the negative electrode active material layer including a plurality of negative electrode active material particles, and
the first solid electrolyte is formed as a plurality of coats covering the respective negative electrode active material particles.
13. The secondary battery according to claim 9 , wherein
the negative electrode includes:
a negative electrode collector; and
a metal layer or an alloy layer disposed on the negative electrode collector.
14. The secondary battery according to claim 13 , wherein
the metal layer or the alloy layer has a standard electrode potential of more positive than −3 V.
15. The secondary battery according to claim 4 , wherein
the positive electrode has an electrode potential of +4 V or more based on the alkaline earth metal.
16. The secondary battery according to claim 1 , wherein
the first solid electrolyte is configured to block electrons from moving between the first electrode and the liquid electrolyte but allow alkaline earth metal ions to move between the first electrode and the liquid electrolyte.