Negative Electrode Active Material, the Method for Preparing the Same, and Device Including the Same
A negative electrode active material includes a carbon-silicon composite, which includes a carbon-based particle and a silicon nanoparticle. The carbon-based particle has a carbon skeleton. The silicon nanoparticle is attach to the carbon skeleton of carbon-based particle. In a peripheral area of the carbon-silicon composite, a mass percentage content A 1 of carbon element and a mass percentage content B 1 of silicon element satisfy 0.8≤B 1 /A 1 ≤2.5.
1 . A negative electrode active material, including a carbon-silicon composite comprising:
a carbon-based particle having a carbon skeleton; and
a silicon nanoparticle attached to the carbon skeleton of the carbon-based particle,
wherein:
in a peripheral area of the carbon-silicon composite, a mass percentage A 1 of carbon element in the carbon-silicon composite relative to a total mass of the carbon-silicon composite and a mass percentage B 1 of silicon element in the carbon-silicon composite relative to the total mass of the carbon-silicon composite satisfy 0.8≤B 1 /A 1 ≤2.5; and
the peripheral area of the carbon-silicon composite is an area extending within r/2 from an outer surface of the carbon-silicon composite towards an interior of the carbon-silicon composite, wherein r represents a short diameter of the carbon-silicon composite.
2 . The negative electrode active material according to claim 1 , wherein:
in a central area of the carbon-silicon composite, a mass percentage content A 2 of carbon element in the carbon-silicon composite relative to the total mass of the carbon-silicon composite and a mass percentage content B 2 of silicon element in the carbon-silicon composite relative to the total mass of the carbon-silicon composite satisfy 1.05≤A 2 /B 2 ≤50; and
the central area of the carbon-silicon composite is an area within r/2 from a centroid of the carbon-silicon composite.
3 . The negative electrode active material according to claim 1 , wherein:
a mass percentage content B of silicon element of the carbon-silicon composite relative to the total mass of the carbon-silicon composite has an increasing trend along a direction from a centroid of the carbon-silicon composite to the outer surface of the carbon-silicon composite.
4 . The negative electrode active material according to claim 1 , wherein:
a mass percentage content B of silicon element of the carbon-silicon composite relative to the total mass of the carbon-silicon composite has an increasing trend along a direction from a centroid of the carbon-silicon composite to the outer surface of the carbon-silicon composite; and
a mass percentage A of the carbon element in the carbon-silicon composite relative to the total mass of the carbon-silicon composite and the mass percentage B of silicon element in the carbon-silicon composite relative to the total mass of the carbon-silicon composite satisfy 1≤A/B≤3.
5 . The negative electrode active material according to claim 1 , wherein:
the carbon-based particle includes one or more of graphite, soft carbon, and hard carbon.
6 . The negative electrode active material according to claim 1 , wherein:
the carbon skeleton is a porous carbon skeleton, and the silicon nanoparticle is located in a pore and/or surface of the porous carbon skeleton.
7 . The negative electrode active material according to claim 1 , wherein:
a particle size D of the silicon nanoparticle satisfies D≤10 nm.
8 . The negative electrode active material according to claim 1 , further comprising:
a conductive layer coated with the carbon-silicon composite.
9 . The negative electrode active material according to claim 7 , wherein:
a thickness of the conductive layer is ≤3.5 μm.
10 . The negative electrode active material according to claim 7 , wherein:
the conductive layer includes a carbon layer and/or a conductive polymer layer.
11 . The negative electrode active material according to claim 1 , wherein:
an average particle size Dv50 of the negative electrode active material satisfies 5 μm≤Dv50≤11 μm.
12 . The negative electrode active material according to claim 1 , wherein:
a specific surface area BET of the negative electrode active material is BET≤4 m 2 /g.
13 . A secondary battery, comprising the negative electrode active material according to claim 1 .
14 . A battery module, comprising the secondary battery according to claim 13 .
15 . A battery pack, comprising the battery module according to claim 14 .
16 . An electrical device, comprising the secondary battery according to claim 13 .
17 . A method for preparing negative electrode active material, comprising:
providing gas containing silicon precursor to a carbon-based particle having a carbon skeleton; and
generating a silicon nanoparticle attached to the carbon skeleton from the silicon precursor by chemical vapor deposition, resulting in a carbon-silicon composite;
wherein:
in a peripheral area of the carbon-silicon composite, a mass percentage A1 of carbon element in the carbon-silicon composite relative to a total mass of the carbon-silicon composite and a mass percentage B 1 of silicon element in the carbon-silicon composite relative to the total mass of the carbon-silicon composite satisfy 0.8≤B 1 /A 1 ≤2.5; and
the peripheral area of the carbon-silicon composite is an area extending within r/2 from an outer surface of the carbon-silicon composite towards an interior of the carbon-silicon composite, wherein r represents a short diameter of the carbon-silicon composite.
18 . The method according to claim 17 , further comprising:
forming a conductive layer on the silicon carbon composite.