Composite anode material including surface-stabilized active material particles and methods of making same
Composite anode materials and methods of making same, the anode materials including capsules including graphene, reduced graphene oxide, graphene oxide, or a combination thereof, and particles of an active material disposed inside of the capsules. The particles may each include a core and a buffer layer surrounding the core. The core may include crystalline silicon, and the buffer layer may include a silicon oxide, a lithium silicate, carbon, or a combination thereof.
1. An anode comprising:
a binder; and
a composite anode material comprising:
capsules comprising graphene, reduced graphene oxide, graphene oxide, or a combination thereof; and
active material particles disposed inside of the capsules, each particle comprising:
a core; and
a buffer layer surrounding the core,
wherein:
the buffer layer and the core comprise different materials:
the binder comprises polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), poly(acrylic) acid, polyethylenetetrafluoroethylene (ETFE), polyamides, and polyimides, polyethylene (UHMW), styrene-butadiene rubber, cellulose, polyacrylate rubber, or a mixture thereof; and
the anode has an internal porosity that ranges from about 40 percent to about 60 percent, as measured by the equation:
Internal
Porosity
(
%
)
=
1
-
(
measured
density
theoretical
density
)
where the measured density is calculated by dividing the mass of a dried electrode by its volume, and the theoretical density is the density of the electrochemically active material that is 100 percent dense.
2. A composite anode material comprising:
capsules comprising graphene, reduced graphene oxide, graphene oxide, or a combination thereof; and
active material particles disposed inside of the capsules, each particle comprising:
a core; and
a buffer layer surrounding the core,
wherein:
the buffer layer and the core comprise different materials;
the capsules have an average particle size that ranges from about 0.5 μm to about 10 μm;
the particles have an average particle size that ranges from about 30 nm to about 500 nm.
3. A composite anode material comprising:
capsules comprising graphene, reduced graphene oxide, graphene oxide, or a combination thereof; and
active material particles disposed inside of the capsules, each particle comprising:
a core; and
a buffer layer surrounding the core,
wherein:
the buffer layer and the core comprise different materials;
the capsules have an average particle size that ranges from about 0.5 μm to about 10 μm; and
the particles have an average particle size of 500 nm or less.