Electrode, secondary battery, battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus

1. A secondary battery comprising:

a cathode;

an anode; and

an electrolytic solution, wherein

the cathode includes particles of a lithium composite oxide, a first compound, and a second compound, the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements,

the first compound is Li 4 Ti 5 O 12 , the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.

2. The secondary battery according to claim 1 , wherein titanium atoms of the first compound and atoms of the second metal element are not constituent atoms of a crystal lattice of the lithium composite oxide.

3. The secondary battery according to claim 1 , wherein the lithium composite oxide includes one or more of nickel (Ni), cobalt (Co), and manganese (Mn) as the transition metal element, and the second compound includes one or more of sodium (Na), lithium (Li), magnesium (Mg), zinc (Zn), manganese (Mn), and barium (Ba) as the second metal element.

4. The secondary battery according to claim 1 , wherein the second compound includes phosphorus (P) as a constituent element.

5. The secondary battery according to claim 1 , wherein the second compound is a phosphate compound.

6. The secondary battery according to claim 1 , wherein the lithium composite oxide includes Co as a constituent element.

7. The secondary battery according to claim 1 , wherein the lithium composite oxide is either or both of compounds represented by Formula (1) and Formula (2) described below, and the second compound is a compound represented by Formula (4) described below,

Li a M1 b M2 c O 2   (1)

where M1 represents one or more of Ni, Co, and Mn; M2 represents one or more of aluminum (Al), magnesium (Mg), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), yttrium (Y), niobium (Nb), molybdenum (Mo), barium (Ba), bismuth (Bi), calcium (Ca), and boron (B); and a to c satisfy 0.01<a<1.3, 0.9<b<1.05, and 0≦c<0.1,

Li d M3 e M4 f O 4   (2)

where M3 represents one or more of Ni, Co, and Mn; M4 represents one or more of Al, Mg, V, Cr, Fe, Cu, Zn, Y, Nb, Mo, Ba, Bi, Ca, and B; and d to f satisfy 0.01<d<1.3, 1.8<e<2.1, and 0≦f<0.2,

M6 j P k O m F n   (4)

where M6 represents one or more of Na, Li, Mg, Zn, Mn, and Ba; and j, k, m, and n satisfy 0<j≦6, 0<k≦5, 0<m≦14, and 0<n≦6.

8. The secondary battery according to claim 1 , wherein an upper limit value of a charge voltage is from about 4.2 volts to about 4.8 volts.

9. The secondary battery according to claim 1 , wherein an upper limit value of a charge voltage is from about 4.25 volts to about 4.8 volts.

10. The secondary battery according to claim 1 , wherein the secondary battery is a lithium ion secondary battery.

11. An electrode comprising:

particles of a lithium composite oxide;

a first compound; and

a second compound, wherein

the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements, the first compound is Li 4 Ti 5 O 12 ,

the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.

12. A battery pack comprising:

a secondary battery;

a control section controlling a usage state of the secondary battery; and

a switch section switching the usage state of the secondary battery according to an instruction of the control section, wherein

the secondary battery includes a cathode, an anode, and an electrolytic solution,

the cathode includes particles of a lithium composite oxide, a first compound, and a second compound,

the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements,

the first compound is Li 4 Ti 5 O 12 , the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.

13. An electric vehicle comprising:

a secondary battery;

a conversion section converting electric power supplied from the secondary battery to drive power;

a drive section operating according to the drive power; and

a control section controlling a usage state of the secondary battery, wherein

the secondary battery includes a cathode, an anode, and an electrolytic solution,

the cathode includes particles of a lithium composite oxide, a first compound, and a second compound,

the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements,

the first compound is Li 4 Ti 5 O 12 , the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.

14. An electric power storage system comprising:

a secondary battery;

one, or two or more electric devices supplied with electric power from the secondary battery; and

a control section controlling the supplying of the electric power from the secondary battery to the electric device, wherein

the secondary battery includes a cathode, an anode, and an electrolytic solution,

the cathode includes particles of a lithium composite oxide, a first compound, and a second compound,

the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements,

the first compound is Li 4 Ti 5 O 12 , the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.

15. An electric power tool comprising:

a secondary battery; and

a movable section being supplied with electric power from the secondary battery, wherein

the secondary battery includes a cathode, an anode, and an electrolytic solution,

the cathode includes particles of a lithium composite oxide, a first compound, and a second compound,

the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements,

the first compound is Li 4 Ti 5 O 12 , the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.

16. An electronic apparatus with a secondary battery as an electric power supply source, the secondary battery comprising:

a cathode;

an anode; and

an electrolytic solution, wherein

the cathode includes particles of a lithium composite oxide, a first compound, and a second compound,

the lithium composite oxide includes lithium (Li) and a transition metal element as constituent elements,

the first compound is Li 4 Ti 5 O 12 , the first compound existing on a surface of and inside of the particles of lithium composite oxide, and

the second compound includes a second metal element different from titanium as a constituent element, the second compound existing on the surface of but not inside of the particles of lithium composite oxide.