ELECTRODES FOR ENERGY STORAGE DEVICES
Disclosed herein is 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; and a polymeric binder comprising a first polymer which is a polymer comprising an acid functional group or a salt of such acid functional group; a polyamide; or an acrylate polymer, and a second polymer.
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; and
a polymeric binder comprising a first polymer which comprises an acid functional group or a salt of such acid functional group; a polyamide; or an acrylate polymer, and a second polymer.
2 . The electrode of claim 1 , wherein network of high aspect ratio carbon elements comprises:
a first set of carbon nanotubes, wherein the first set of carbon nanotubes comprises 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.
3 . The electrode of claim 2 , wherein the first set of carbon nanotubes comprises single wall carbon nanotubes.
4 . The electrode of claim 2 , wherein the second set of carbon nanotubes comprises multiwall carbon nanotubes.
5 . The electrode of claim 2 , wherein:
the first set of carbon nanotubes comprises single wall carbon nanotubes;
the second set of carbon nanotubes comprises multi-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.
6 . The electrode of claim 1 , wherein the network of high aspect ratio carbon elements comprises a set of multi-wall carbon nanotubes, preferably 0.8 to 2.6, more preferably between 1 and 1.8 wt % of multi-wall carbon nanotubes by weight of the active layer.
7 . The electrode of claim 3 , wherein the active layer comprises between 0.2 and 0.6, preferably between 0.3 and 0.5, wt % of single wall carbon nanotubes by weight of the active layer.
8 . The electrode of claim 1 wherein the second polymer comprises polyvinyl pyrrolidone or a cellulose polymer.
9 . An energy storage device comprising:
an electrolyte; and
the electrode of claim 5 .
10 . The energy storage device of claim 9 , wherein the multi-wall nanotubes swell more than the single-wall carbon nanotubes when wetted with the electrolyte.
11 . The electrode of claim 5 , wherein the multi-wall carbon nanotubes comprise:
an average diameter of between 6 nm and 10 nm;
an average wall thickness of between 6 nm and 7 nm; and
an average length of about 10 nanometers to 20 micrometers.
12 . The electrode of claim 5 , wherein the single-wall carbon nanotubes comprise:
an average diameter of between 0.5 nm and 5 nm;
and an average length of about 10 nm to 20 micrometers.
13 . The electrode of claim 5 , wherein the single-wall carbon nanotubes comprise:
an average diameter of between 3 nm and 5 nm; and
an average length of at least 200 micrometers.
14 . The electrode of claim 5 , wherein after wetted with an electrolyte an average thickness of the electrode increases by less than 10%.
15 . The electrode of claim 5 , wherein an average aspect ratio of the second set of carbon nanotubes is larger than an average aspect ratio of the first set of carbon nanotubes.
16 . An energy storge device comprising:
a housing;
an electrolyte;
a first current collector;
an anode active material disposed on the first current collector; where the anode active material comprises a network of high aspect ratio carbon elements defining void spaces within the network;
a plurality of anode active material particles disposed in the void spaces within the network; and
an anode polymeric binder, the polymeric binder comprising a first polymer which is a polymer comprising an acid functional group or a salt of such acid functional group or an acrylate polymer; and
a second current collector;
a cathode active material disposed on the second current collector; where the cathode active material comprises a network of high aspect ratio carbon elements defining void spaces within the network;
a plurality of cathode active material particles disposed in the void spaces within the network; where the cathode active material comprises a combination of nickel, manganese and cobalt; and
a cathode polymeric binder, the polymeric binder comprising a first polymer which is a polymer comprising an acid functional group or a salt of such acid functional group; a polyamide; or an acrylate polymer,
wherein at least one of the anode polymeric binder and the cathode polymeric binder further comprise a second polymer.
17 . The energy storage device of claim 16 , wherein the anode polymeric binder comprises a second polymer, preferably a cellulose polymer, more preferably carboxymethyl cellulose.
18 . The energy storage device of claim 16 , wherein the cathode polymeric binder comprises a second polymer.
19 . The energy storage device of claim 18 , wherein the second polymer is polyvinylpyrollidone.
20 . The electrode of claim 12 , wherein the single-wall carbon nanotubes comprise an average diameter of between 3 and 5 nm and an average length of about 7 to 8 micrometers.