Negative electrode material for lithium-ion secondary battery and use thereof
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). 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. Further, the porous carbon (A) has a BET specific surface area of 800 m 2 /g or more, and the Si-containing compound (B) is contained in pores of the porous carbon (A). Also disclosed is a negative electrode sheet including the negative electrode material and a lithium-ion secondary battery including the negative electrode sheet.
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, V 2 /V 0 <0.10, and V 3 /V 0 >0.50,
when a total pore volume at a 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 ,
a cumulative pore volume at a relative pressure P/P 0 =10 −2 is defined as V 3 in the 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) 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.
3. The negative electrode material for a lithium-ion secondary battery according to claim 1 , wherein the composite (C) has a 50% particle size (D V50 ) of 2.0 μm or more and 30.0 μm or less, has a 10% particle size (D V10 ) 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. 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).
9. 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).
10. 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.
11. 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.
12. 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 .
13. A lithium-ion secondary battery having a negative electrode comprising the negative electrode sheet according to claim 12 .