Electrode active material for magnesium battery
Provided are an electrode active material for a magnesium battery, including a complex transition metal oxide which is represented by a Formula 1 below and which includes λ-MnO 2 phase having a cubic structure at a percentage of 60% or higher, an electrode and a magnesium battery including the same, and a method of preparing the electrode active material for a magnesium battery: <Formula 1> M x Mn y O z In the Formula 1, 0<x≤1, 0.25≤y≤1, and 1≤z<3; and M is at least one metal selected from Mg 2+ , Ca 2+ , Na + , K + , and Zn 2+ .
1. An electrode active material for a magnesium battery, the electrode active material comprising a complex transition metal oxide which is represented by a Formula 1 below and which includes λ-MnO 2 phase having a cubic structure at a percentage of 60% or higher:
(Mg) v MnO w <Formula 1>
In the Formula 1,
0<v≤0.2 and 1<w<2.5.
2. The electrode active material for a magnesium battery of claim 1 , wherein the average oxidation number of the Mn positive ion of the complex transition metal oxide is +3.6 or higher.
3. The electrode active material for a magnesium battery of claim 1 , wherein the percentage of Mn 4+ with respect to the oxidation number of the total Mn positive ions is 60% or higher in an XPS analysis of the complex transition metal oxide.
4. The electrode active material for a magnesium battery of claim 1 , wherein the content of Mg included in the complex transition metal oxide is more than 0 wt % and less than 10 wt % with respect to the total weight of the complex transition metal oxide.
5. The electrode active material for a magnesium battery of claim 1 , wherein the average particle diameter of the complex transition metal oxide is from about 1 nm to about 200 nm.
6. The electrode active material for a magnesium battery of claim 1 , wherein the shape of the complex transition metal oxide includes a needle-like shape and a spherical shape.
7. The electrode active material for a magnesium battery of claim 1 , wherein the complex transition metal oxide further includes a phase having a Birnessite structure.
8. The electrode active material for a magnesium battery of claim 1 , wherein the electrode active material is a positive electrode active material.
9. An electrode for a magnesium battery, comprising the electrode active material according to claim 1 .
10. A magnesium battery comprising:
a positive electrode including the electrode active material according to claim 8 ;
a negative electrode; and
an electrolyte.
11. The magnesium battery of claim 10 , wherein the operation potential of the positive electrode active material is from about 1 V to about 4 V (vs. Mg/Mg 2+ ).
12. The magnesium battery of claim 10 , wherein the negative electrode comprises a magnesium metal, a magnesium metal-based alloy, a magnesium intercalating compound, or a carbonaceous material.
13. The magnesium battery of claim 10 , further comprising a separator interposed between the positive electrode and the negative electrode.
14. A method of preparing an electrode active material for a magnesium battery, the method comprising
obtaining a complex transition metal oxide having a spinel structure by a solid phase method or a liquid phase method; and
preparing a complex transition metal oxide which is represented by a Formula 1 below and which includes λ-MnO 2 phase having a cubic structure at a percentage of 60% or higher by treating with an acid the complex transition metal oxide having the spinel structure:
(Mg) v MnO w <Formula 1>
In the Formula 1,
0<v≤0.2 and 1<w<2.5.
15. The method of preparing an electrode active material for a magnesium battery of claim 14 , wherein the complex transition metal oxide having the spinel structure comprises a complex transition metal oxide having a spinel structure prepared by a Pechini method.
16. The method of preparing an electrode active material for a magnesium battery of claim 14 , wherein the average particle diameter of the complex transition metal oxide represented by the Formula 1 is from about 1 nm to about 200 nm.
17. The method of preparing an electrode active material for a magnesium battery of claim 14 , wherein, in the Formula 1, 0<x≤0.5, 0.25≤y≤1, and 1≤z<2.5.
18. The method of preparing an electrode active material for a magnesium battery of claim 14 , wherein the acid concentration during the acid treatment is from about 0.1 M to about 3 M.
19. The method of preparing an electrode active material for a magnesium battery of claim 14 , wherein the acid used for the acid treatment is nitric acid, sulfuric acid, hydrochloric acid, acetic acid, or a salt thereof.
20. The method of preparing an electrode active material for a magnesium battery of claim 14 , wherein the content of Mg included in the complex transition metal oxide represented by the Formula 1 is more than 0 wt % and less than 10 wt % with respect to the total weight of the complex transition metal oxide.