Negative electrode material for nonaqueous secondary batteries, negative electrode for nonaqueous secondary batteries, and nonaqueous secondary battery
Provided are: a negative electrode material for nonaqueous secondary batteries, which can yield a high-capacity nonaqueous secondary battery having excellent discharge rate characteristics; and a negative electrode for nonaqueous secondary batteries and a nonaqueous secondary battery. Also provided is a nonaqueous secondary battery having excellent charge-discharge efficiency. The negative electrode material for nonaqueous secondary batteries includes carbonaceous particles (A) and silicon oxide particles (B), and satisfies the followings: a) the average particle size (50% cumulative particle size from the smaller particle side; d50) is 3 μm to 30 μm, and the 10% cumulative particle size from the smaller particle side (d10) is 0.1 μm to 10 μm; b) the ratio (R1=d90/d10) between the 90% cumulative particle size from the smaller particle side (d90) and the d10 is 3 to 20; and c) the ratio (R2=d50/d10) between the d50 and the d10 is 1.7 to 5.
1. A negative electrode material for nonaqueous secondary batteries, the negative electrode material comprising carbonaceous particles (A) and silicon oxide particles (B), wherein both the carbonaceous particles (A) and the silicon oxide particles (B) satisfy the following a) to c):
a) the average particle size (50% cumulative particle size from the smaller particle side; d50) is 3 μm to 30 μm, and the 10% cumulative particle size from the smaller particle side (d10) is 0.1 μm to 10 μm;
b) the ratio (R1=(d90/d10) between the 90% cumulative particle size from the smaller particle side (d90) and the d10 is 3 to 20; and
c) the ratio (R2=(d50/d10) between the d50 and the d10 is 1.7 to 5,
wherein
the carbonaceous particles (A) comprise natural graphite,
the carbonaceous particles (A) do not contain an artificial graphite, and
the carbonaceous particles (A) have a specific surface area of 20 m 2 /g or smaller.
2. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the ratio (R3=(d50 b /d50 a ) between the average particle size of the silicon oxide particles (B) (50% cumulative particle size from the smaller particle side; d50 b ) and the average particle size of the carbonaceous particles (A) (50% cumulative particle size from the smaller particle side; d50 a ) is 0.01 to 1.
3. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the ratio (R4=d50 b /d10 a ) between the d50 b of the silicon oxide particles (B) and the 10% cumulative particle size from the smaller particle side (d10 a ) of the carbonaceous particles (A) is 0.01 to 2.
4. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein, with regard to the carbonaceous particles (A),
the d50 a is 5 μm to 30 μm, and
the ratio (R1 a =d90 a /d10 a ) between the 90% cumulative particle size from the smaller particle side (d90 a ) and the 10% cumulative particle size from the smaller particle side (d10 a ) is 3 to 10.
5. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein, with regard to the silicon oxide particles (B),
the d50 b is 0.1 μm to 20 μm, and
the ratio (R1 b =d90 b /d10 b ) between the 90% cumulative particle size from the smaller particle side (d90 b ) and the 10% cumulative particle size from the smaller particle side (d10 b ) is 3 to 15.
6. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the 10% cumulative particle size from the smaller particle side (d10 b ) of the silicon oxide particles (B) is 0.001 μm to 6 μm.
7. The negative electrode material for nonaqueous secondary batteries according to claim 1 , comprising the carbonaceous particles (A) and the silicon oxide particles (B) at a ratio of 30:70 to 99:1 ([weight of carbonaceous particles (A)]:[weight of silicon oxide particles (B)]).
8. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the carbonaceous particles (A) have a circularity of 0.88 or higher as determined by a flow-type particle image analysis.
9. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the carbonaceous particles (A) comprise a spheroidized graphite.
10. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the ratio (M O /M Si ) of the number of oxygen atoms (Mo) with respect to the number of silicon atoms (M Si ) in the silicon oxide particles (B) is 0.5 to 1.6.
11. The negative electrode material for nonaqueous secondary batteries according to claim 1 , wherein the silicon oxide particles (B) comprise zero-valent silicon atoms.
12. The negative electrode material for nonaqueous secondary batteries according to claim 1 , comprising silicon microcrystals in the silicon oxide particles (B).
13. A negative electrode for nonaqueous secondary batteries, the negative electrode comprising:
a current collector; and
an active substance layer formed on the current collector,
wherein the active substance layer comprises the negative electrode material for nonaqueous secondary batteries according to claim 1 .
14. A nonaqueous secondary battery comprising:
a positive electrode;
a negative electrode; and
an electrolyte,
wherein the negative electrode is the negative electrode for nonaqueous secondary batteries according to claim 13 .
15. The nonaqueous secondary battery according to claim 14 , wherein the electrolyte is an electrolyte solution contained in a nonaqueous solvent.
16. The nonaqueous secondary battery according to claim 15 , wherein
the electrolyte solution contains lithium difluorophosphate, and
the content thereof is 0.01% by weight to 2% by weight with respect to the whole electrolyte solution.