ANODE ELECTRODE INCLUDING DOPED ELECTRODE ACTIVE MATERIAL AND ENERGY STORAGE DEVICE INCLUDING SAME

1 . An anode electrode for an energy storage device comprising a doped active material represented by a formula:

ATi 2−X M X (PO 4 ) 3 ,

wherein:

A comprises at least 51 atomic percent sodium and 0 to 49 atomic percent alkali metals other than sodium;

X ranges from about 0.1 to about 0.6, and

M is selected from at least one of Mg, Ca, Mn, Mo, Nb, Ni, W, Zn, Zr, Al, Ge, and Si.

2 . The electrode of claim 1 , wherein A comprises 60 to 100 atomic percent sodium, and 0 to 40 atomic percent lithium.

3 . The electrode of claim 2 , wherein A consists essentially of sodium and the doped active material comprises doped sodium titanium phosphate having a NASICON structure and represented by a formula NaTi 2−X M X (PO 4 ) 3 .

4 . The electrode of claim 1 , wherein M is selected from the group consisting of at least one of Zn, Ca and Mg.

5 . The electrode of claim 1 , wherein:

M consists essentially of Zn; and

the doped active material comprises zinc doped sodium titanium phosphate having a NASICON structure and represented by a formula NaTi 2−X Zn X (PO 4 ) 3 , wherein X ranges from about 0.2 to about 0.45.

6 . (canceled)

7 . The electrode of claim 1 , wherein:

M consists essentially of Zn and Ca; and

the doped active material comprises zinc and calcium doped sodium titanium phosphate having a NASICON structure and represented by a formula NaTi 2−(X+Y) Zn X Ca Y (PO 4 ) 3 , wherein Y ranges from about 0.035 to about 0.3.

8 . (canceled)

9 . The electrode of claim 1 , wherein:

M consists essentially of Zn and Mg; and

the doped active material comprises zinc and manganese doped sodium titanium phosphate having a NASICON structure and represented by a formula NaTi 2−(X+Y) Zn X Mg Y (PO 4 ) 3 , wherein Y ranges from about 0.035 to about 0.3.

10 . (canceled)

11 . The electrode of claim 1 , wherein:

M X comprises at least two elements M′ and N;

the doped active material is represented by a formula ATi 2−(Z+Y) M′ Z N Y (PO 4 ) 3 , wherein Z ranges from about 0.1 to about 0.565 and Y ranges about 0.035 to about 0.3; and

M′ and N comprise different elements selected from Mg, Ca, Mn, Mo, Nb, Ni, W, Zn, Zr, Al, Ge and Si.

12 . The electrode of claim 1 , further comprising activated carbon mixed with the active material, wherein a mass ratio of the active material to the activated carbon ranges from about 1:9 to about 9:1.

13 . The electrode of claim 1 , wherein:

the doped active material comprises sodium titanium phosphate having a NASICON structure doped with zinc or a combination of zinc with at least one of calcium and magnesium; and

the doped sodium titanium phosphate active material includes only the sodium, titanium, phosphorus and oxygen of the NASICON structure and a dopant selected from one or more zinc, calcium, magnesium and lithium, and excludes all other elements or compounds above an unavoidable trace impurity level; and

the doped sodium titanium phosphate material excludes halogen and hydroxyl compounds.

14 . (canceled)

15 . The electrode of claim 1 , wherein the doped active material comprises a doped sodium titanium phosphate having a NASICON structure in which dopant atoms are present in the sodium titanium phosphate material throughout a thickness of the anode electrode and not just in a shell or coating on a surface of the anode electrode.

16 . The electrode of claim 15 , wherein a dopant is selected from one or more zinc, calcium, magnesium and lithium, and excludes all other elements or compounds above an unavoidable trace impurity level.

17 . The electrode of claim 1 , wherein the electrode is free of polymers, is free of organic materials, or is free of both polymers and organic materials.

18 . An energy storage device, comprising:

electrochemical energy storage cells connected electrically in series, wherein each cell comprises:

the anode electrode of claim 1 ;

a positive cathode electrode comprising a cubic spinel λ-MnO 2 -type material; and

an aqueous electrolyte comprising at least one of Na 2 SO 4 , K 2 SO 4 , and Li 2 SO 4 .

19 . (canceled)

20 . A method of making an anode electrode for an energy storage device comprising:

combining a dopant selected from at least one of elemental Mg, Ca, Mn, Mo, Nb, Ni, W, Zn, Zr, Al, Ge, and Si, an oxide thereof or a hydroxide thereof with titanium, sodium and phosphate precursor materials;

heating the combined dopant and precursor materials to form a doped sodium titanium phosphate material; and

providing the doped sodium titanium phosphate material into an anode electrode of the energy storage device.

21 . (canceled)

22 . An anode electrode for an energy storage device comprising a doped active material represented by the formula:

Na 1−X D X Ti 2−Y M Y (P 1−Z E Z O 4 ) 3 ,

wherein:

X ranges from 0 to about 0.49;

Y ranges from 0 to about 0.6;

Z ranges from 0 to about 0.4;

X+Y+Z>0;

D comprises Li, an alkaline earth metal or a combination thereof;

M comprises an alkaline earth metal, a transition metal, a P-block metal element or any combination thereof; and

E comprises a metalloid.

23 . The electrode of claim 22 , wherein:

E comprises silicon; and

Z ranges from about 0.1 to about 0.4.

24 . The electrode of claim 22 , wherein M is selected from the group consisting of Zn, Ca, Mg, or any combination thereof and D is selected from the group consisting of Ca, Mg, Li, or any combination thereof.

25 . The electrode of claim 24 , wherein:

D comprises at least one of Ca and Mg;

M consists essentially of Zn;

X>0; and

Y ranges from about 0.2 to about 0.45.

26 . The electrode of claim 22 , wherein X+Y>0 and wherein D comprises two or more of Li or alkaline earth metals.