Negative electrode having intermetallic compound that occludes/desorbs lithium as an active material layer on collector for non-aqueous secondary battery and non-aqueous secondary battery using the same
View Patent ↗A negative electrode of the present invention has an active material layer composed of an intermetallic compound on a collector. The intermetallic compound is capable of occluding/desorbing lithium and contains at least one kind of element A selected from Sn, In, Ge, Ga, Pb, Al, Sb, and Si, and an element X that does not substantially react with Li. In the negative electrode, a ratio I b /I a of highest peak intensities I a and I b of X-ray diffraction peaks derived from the intermetallic compound and the element A is 0.1 or less. By configuring a non-aqueous secondary battery using the above-mentioned negative electrode, the charging/discharging efficiency and cycle characteristics of a thin film electrode used for the negative electrode of the non-aqueous secondary battery are enhanced.
1. A non-aqueous secondary battery comprising:
a positive electrode;
a non-aqueous electrolyte; and
a negative electrode comprising a collector, an intermetallic compound as an active material layer that occludes/desorbs lithium, and a conductive layer on the collector,
wherein a conductive layer is disposed between the active material layer and the collector, contains at least one kind of element selected from Ti, Ni, Zr, W and Ag, and has a thickness of 0.05 to 0.5 μm, and
wherein the intermetallic compound is a single phase and contains at least one kind of element A selected from Sn, In, Ge, Ga, Pb, Al, Sb, and Si, and an element X that does not substantially react with Li, wherein X is at least one kind of element selected from Cu, Ni, Fe, Mn, Co, Cr, Mo, W, Ti, and Zr, and
wherein in X-ray diffraction measurement with a CuKα-ray of the active material layer, highest peak intensities of diffraction lines derived from the intermetallic compound and the element A are represented by I a and I b , respectively, and an intensity ratio I b /I a is 0.1 or less.
2. The non-aqueous secondary battery according to claim 1 , wherein the element X is at least one kind of element selected from Cu, Ni, and Fe.
3. The non-aqueous secondary battery according to claim 1 , wherein the intermetallic compound is a NiAs type intermetallic compound belonging to a space group P6 3 /mmc.
4. The non-aqueous secondary battery according to claim 3 , wherein, the NiAs type intermetallic compound is Cu 6 Sn 5 .
5. The non-aqueous secondary battery according to claim 1 , wherein a highest peak intensity of a diffraction line derived from an intermetallic compound phase other than the intermetallic compound capable of occluding/desorbing lithium is represented by I c , and an intensity ratio I c /I a is 0.05 or less.
6. The non-aqueous secondary battery according to claim 1 , wherein a thickness of the active material layer is 20 μm or less.
7. The non-aqueous secondary battery according to claim 1 , wherein a thickness of the active material layer is 10 μm or less.
8. The non-aqueous secondary battery according to claim 1 , wherein the collector is composed of at least one kind of element selected from Cu, Ni, Fe, and Ti, and an alloy thereof.