Negative-electrode material for Li-ion secondary cell, method for manufacturing said material, negative electrode for Li-ion-secondary-cell, and Li-ion secondary cell
The present invention provides a Li-ion secondary cell negative-electrode material with which it is possible to adequately suppress reductive decomposition of a liquid electrolyte by an active material during charging, the Li-ion secondary cell negative-electrode material exhibiting a high discharge capacity that exceeds the theoretical capacity of graphite and exceptional initial charging efficiency and cycle characteristics. In this negative-electrode material for a Li-ion secondary cell, the surfaces of particles of SiO x (O≤x<2) contain Li and at least one metallic element M selected from among Si, Al, Ti, and Zr, and have a coating of a Li-containing oxide comprising a composition in which M/Li>5 with respect to the molar ratio.
1. A negative electrode material for a Li-ion secondary battery, the negative electrode material having, on SiO x (O≤x<2) particle surfaces, coatings of a Li-containing oxide that includes Li and at least one kind of a metal element M selected from Al, Ti and Zr and has a composition of M/Li≥6 in molar ratio.
2. The negative electrode material for a Li-ion secondary battery according to claim 1 , wherein the M/Li is 6≤M/Li<100.
3. The negative electrode material for a Li-ion secondary battery according to claim 1 , wherein a content of the Li-containing oxide is 2 to 10 mass %.
4. A negative electrode for a Li-ion secondary battery containing the negative electrode material according to claim 1 .
5. A Li-ion secondary battery including the negative electrode for a Li-ion secondary battery according to claim 4 .
6. A manufacturing method of a negative electrode material for a Li-ion secondary battery comprising dispersing SiO x (O≤x<2) particles in an oxide precursor solution containing at least one kind of a metal element M selected from Al, Ti and Zr, and Li, and performing heat treatment at temperature in a range of 200 to 1,200° C. after drying, thereby obtaining the negative electrode material according to claim 1 .
7. The negative electrode material for a Li-ion secondary battery according to claim 2 , wherein a content of the Li-containing oxide is 2 to 10 mass %.
8. A negative electrode for a Li-ion secondary battery containing the negative electrode material according to claim 2 .
9. A negative electrode for a Li-ion secondary battery containing the negative electrode material according to claim 3 .
10. A negative electrode for a Li-ion secondary battery containing the negative electrode material according to claim 7 .
11. A Li-ion secondary battery including the negative electrode for a Li-ion secondary battery according to claim 8 .
12. A Li-ion secondary battery including the negative electrode for a Li-ion secondary battery according to claim 9 .
13. A Li-ion secondary battery including the negative electrode for a Li-ion secondary battery according to claim 10 .
14. A manufacturing method of a negative electrode material for a Li-ion secondary battery comprising dispersing SiO x (O≤x<2) particles in an oxide precursor solution containing at least one kind of a metal element M selected from Al, Ti and Zr, and Li, and performing heat treatment at temperature in a range of 200 to 1,200° C. after drying, thereby obtaining the negative electrode material according to claim 2 .
15. A manufacturing method of a negative electrode material for a Li-ion secondary battery comprising dispersing SiO x (O≤x<2) particles in an oxide precursor solution containing at least one kind of a metal element M selected from Al, Ti and Zr, and Li, and performing heat treatment at temperature in a range of 200 to 1,200° C. after drying, thereby obtaining the negative electrode material according to claim 3 .
16. A manufacturing method of a negative electrode material for a Li-ion secondary battery comprising dispersing SiO x (O≤x<2) particles in an oxide precursor solution containing at least one kind of a metal element M selected from Al, Ti and Zr, and Li, and performing heat treatment at temperature in a range of 200 to 1,200° C. after drying, thereby obtaining the negative electrode material according to claim 7 .
17. A Li-ion secondary battery including the negative electrode for a Li-ion secondary battery according to claim 1 , wherein x=0 and the Li-ion secondary battery having silicon as an active material particle has at least one of:
(i) initial capacity of 445 mAh/g or more,
(ii) 1C charging rate of 50.7% or more,
(iii) 2.5C discharging rate of 89.8% or more,
(iv) efficiency of each operation of 30 cycles of 99.0% or more, and
(v) capacity retention rate of 30 cycles of 74.4% or more.