ELECTRODES FOR ENERGY STORAGE DEVICES
An electrode for an energy storage device is disclosed. The electrode includes an active layer. The active layer includes a network of high aspect ratio carbon elements defining void spaces within the network, a plurality of electrode active material particles disposed in the void spaces within the network, wherein the active material particles comprise silicon, and a polymeric additive, the polymeric additive being at least one of a polyolefin, a Poly(acrylic acid), and a styrene-butadiene rubber (SBR).
1 . An electrode, comprising:
an active layer comprising:
a network of high aspect ratio carbon elements defining void spaces within the network;
a plurality of electrode active material particles disposed in the void spaces within the network, wherein the active material particles comprise silicon; and
a polymeric additive, the polymeric additive being at least one of a polyolefin, a poly(acrylic acid), and a styrene-butadiene rubber (SBR).
2 . The electrode of claim 1 , wherein the silicon comprised in the electrode active material particles is in the form of SiO.
3 . The electrode of claim 1 , wherein the silicon comprised in the electrode active material is microsilicon.
4 . The electrode of claim 1 , wherein the silicon comprised in the comprised in the electrode active material is greater than fifty percent of the active layer by weight.
5 . The electrode of claim 1 , wherein the silicon comprised in the comprised in the electrode active material is at least eighty percent of the active layer by weight.
6 . The electrode of claim 1 , wherein:
the network of high aspect ratio carbon elements comprises a mesh of carbon nanotubes; and
the mesh of carbon nanotubes maintains electrical connection among at least a subset of the carbon nanotubes comprised in the mesh during expansion of the Silicon.
7 . The electrode of claim 1 , wherein:
the network of high aspect ratio carbon elements comprises a mesh of carbon nanotubes; and
the mesh of carbon nanotubes maintains electrical connection among at least a subset of the carbon nanotubes comprised in the mesh during a charging and discharging of a battery in which the electrode is comprised.
8 . The electrode of claim 1 , wherein the network of high aspect ratio carbon elements comprises:
a first set of carbon nanotubes, wherein the first set of carbon nanotubes comprise a plurality of first carbon nanotubes or a plurality of bundles of first carbon nanotubes; and
a second set of carbon nanotubes, wherein:
the second set of carbon nanotubes comprise a plurality of second carbon nanotubes or a plurality of bundles of second carbon nanotubes; and
the second set of carbon nanotubes has one or more properties different from the first set of carbon nanotubes.
9 . The electrode of claim 8 , wherein the first set of carbon nanotubes comprises multi-wall nanotubes.
10 . The electrode of claim 8 , wherein the second set of carbon nanotubes comprises single wall nanotubes.
11 . The electrode of claim 8 , wherein:
the first set of carbon nanotubes comprises multi-wall carbon nanotubes;
the second set of carbon nanotubes comprises single-wall carbon nanotubes; and
a ratio of an amount by weight of the first set of carbon nanotubes to the second set of carbon nanotubes is about 2:1.
12 . The electrode of claim 8 , wherein the first set of carbon nanotubes and the second set of carbon nanotubes form a mesh that maintains electrical connection among carbon nanotubes comprised in the mesh during a charging and discharging of a battery in which the electrode is comprised.
13 . The electrode of claim 8 , wherein after wetted with an electrolyte an average thickness of the multi-wall carbon nanotubes increases less than 10%.
14 . The electrode of claim 8 , wherein a first average aspect ratio of the first set of carbon nanotubes is larger than a second average aspect ratio of the second set of carbon nanotubes.
15 . The electrode of claim 8 , wherein an average aspect ratio of the first set of carbon nanotubes is at least 100 microns.
16 . The electrode of claim 1 , wherein the network of high aspect ratio carbon elements comprises:
a first set of carbon nanotubes, wherein the first set of carbon nanotubes comprise a plurality of first carbon nanotubes or a plurality of bundles of first carbon nanotubes;
a second set of carbon nanotubes, wherein:
the second set of carbon nanotubes comprise a plurality of second carbon nanotubes or a plurality of bundles of second carbon nanotubes; and
the second set of carbon nanotubes has one or more properties different from the first set of carbon nanotubes; and
graphite particles.
17 . The electrode of claim 16 , wherein the network of high aspect ratio carbon elements comprises approximately 5% graphite by weight of the active layer.
18 . The electrode of claim 16 , wherein:
the first set of carbon nanotubes comprises multi-wall carbon nanotubes;
the second set of carbon nanotubes comprises single-wall carbon nanotubes;
the network of high aspect ratio carbon elements is approximately 2% single-wall carbon nanotubes by weight.
19 . The electrode of claim 16 , wherein:
the first set of carbon nanotubes comprises multi-wall carbon nanotubes;
the second set of carbon nanotubes comprises single-wall carbon nanotubes;
the network of high aspect ratio carbon elements is approximately 0.5% single-wall carbon nanotubes by weight of the active layer.
20 . The electrode of claim 16 , wherein:
the first set of carbon nanotubes comprises multi-wall carbon nanotubes;
the second set of carbon nanotubes comprises single-wall carbon nanotubes;
the network of high aspect ratio carbon elements is less than or approximately equal to 2% single-wall carbon nanotubes by weight of the active layer.