NEGATIVE ELECTRODE MATERIAL FOR LITHIUM-ION SECONDARY BATTERY AND USE THEREOF
Provided is a negative electrode material for a lithium-ion secondary battery capable of providing a high capacity lithium-ion secondary battery. A negative electrode material for a lithium-ion secondary battery containing a composite (C) that contains a porous carbon (A) and a Si-containing compound (B), wherein the porous carbon (A) satisfies V 1 /V 0 >0.80 and V 2 /V 0 <0.10, when a total pore volume at the maximum value of a relative pressure P/P 0 is defined as V 0 and P 0 is a saturated vapor pressure, a cumulative pore volume at a relative pressure P/P 0 =0.1 is defined as V 1 , and a cumulative pore volume at a relative pressure P/P 0 =10 −7 is defined as V 2 in a nitrogen adsorption test, and has a BET specific surface area of 800 m 2 /g or more; and wherein the Si-containing compound (B) is contained in pores of the porous carbon (A).
1 . A negative electrode material for a lithium-ion secondary battery comprising a composite (C), the composite (C) comprising a porous carbon (A) and a Si-containing compound (B), wherein the porous carbon (A) and the Si-containing compound (B) are as follows:
wherein the porous carbon (A) satisfies V 1 /V 0 >0.80 and V 2 /V 0 <0.10,
when a total pore volume at the maximum value of a relative pressure P/P 0 is defined as V 0 and P 0 is a saturated vapor pressure,
a cumulative pore volume at a relative pressure P/P 0 =0.1 is defined as V 1 , and
a cumulative pore volume at a relative pressure P/P 0 =10 −7 is defined as V 2 in a nitrogen adsorption test,
and has a BET specific surface area of 800 m 2 /g or more; and
wherein the Si-containing compound (B) is contained in pores of the porous carbon (A).
2 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the porous carbon (A) satisfies V 3 /V 0 >0.50,
when a cumulative pore volume at a relative pressure P/P 0 =10 −2 is defined as V 3 in the nitrogen adsorption test.
3 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the porous carbon (A) has the total pore volume V 0 in the nitrogen adsorption test of 0.4 cm 3 /g or more and less than 1.0 cm 3 /g.
4 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the composite (C) has a 50% particle size (Dv 50 ) of 2.0 μm or more and 30.0 μm or less, has a 10% particle size (Dv 10 ) of 1.0 μm or more in a volume-based cumulative particle size distribution by laser diffraction method, and has a BET specific surface area of 0.5 m 2 /g or more and 40.0 m 2 /g or less.
5 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the composite (C) has an average aspect ratio of 1.00 or more and 2.50 or less.
6 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the Si-containing compound (B) is one or more selected from silicon elemental substance, silicon oxide, and silicon carbide.
7 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein a Si content in the composite (C) is 15% by mass or more and 85% by mass or less.
8 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the Si content in the composite (C) is 15% or more and 95% or less with respect to a theoretical value, when a true density of Si is set to 2.32 g/cm 3 with respect to the total pore volume V 0 of the porous carbon (A), the theoretical value of the Si content (theoretical Si content) when total pores of the porous carbon (A) are occupied by Si is determined from:
theoretical
Si
content
(
%
)
=
(
V
0
[
cm
3
/
g
]
×
1
[
g
]
×
2.32
[
g
/
cm
3
]
)
/
(
(
V
0
[
cm
3
/
g
]
×
1
[
g
]
×
2.32
[
g
/
cm
3
]
)
+
1
[
g
]
)
×
100.
9 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein (I Si /I G ) is less than 0.30 with respect to a peak intensity (I Si ) in the vicinity of 470 cm −1 and a peak intensity (I G ) in the vicinity of 1580 cm −1 measured by Raman spectroscopy of the composite (C).
10 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein (I D /I G ) is 0.50 or more and less than 1.50 with respect to a peak intensity (I G ) in the vicinity of 1580 cm −1 and a peak intensity (I D ) in the vicinity of 1350 cm −1 measured by Raman spectroscopy of the composite (C).
11 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein in an XRD pattern using a Cu-Kα ray of the composite (C), a full width at half maximum of a peak of a 111 plane of Si is 3.00° or more.
12 . The negative electrode material for a lithium-ion secondary battery according to claim 1 , further comprising inorganic particles and a polymer on a portion or the entire surface of the composite (C), wherein the inorganic particles comprise one or more selected from graphite and carbon black, and a content of the polymer is 0.1 to 10.0% by mass.
13 . A negative electrode sheet comprising a sheet-like current collector and a negative electrode layer covering the current collector, the negative electrode layer comprising a binder and the negative electrode material for a lithium-ion secondary battery according to claim 1 .
14 . A lithium-ion secondary battery having a negative electrode comprising the negative electrode sheet according to claim 13 .