Electrodes for energy storage devices
Disclosed herein is an apparatus comprising an electrode 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 enmeshed in the network; and a surface treatment on the surface of the high aspect ratio carbon elements which promotes adhesion between the high aspect ratio carbon elements and the active material particles.
1 . An energy storage apparatus comprising:
an electrode active layer in the energy storage apparatus, 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 enmeshed in the network; and
a surface treatment on the surface of the high aspect ratio carbon elements which promotes adhesion between the high aspect ratio carbon elements and the plurality of electrode active material particles; wherein the surface treatment comprises at least one compound selected from the group consisting of: hexadecyltrimethylammonium tetrafluoroborate, N-(cocoalkyl)-N,N,N-trimethylammonium methyl sulfate, cocamidopropyl betaine hexadecyltrimethylammonium acetate, and hexadecyltrimethylammonium nitrate.
2 . The apparatus of claim 1 , wherein the high aspect ratio carbon elements comprise elements each having two major dimensions and one minor dimension, wherein the ratio of the length of each of the major dimensions is at least 10 times that of the minor dimension.
3 . The apparatus of claim 1 , wherein the high aspect ratio carbon elements comprise elements each having one major dimension and two minor dimension, wherein the ratio of the length of each the major dimension is at least 10 times that of each of the minor dimensions.
4 . The apparatus of claim 1 , wherein the high aspect ratio carbon elements comprise carbon nanotubes or carbon nanotube bundles.
5 . The apparatus of claim 1 , wherein the high aspect ratio carbon elements comprise graphene flakes.
6 . The apparatus of claim 1 , wherein the electrode active layer contains less than 10% by weight of polymeric binders disposed in the void spaces.
7 . The apparatus of claim 1 , wherein the electrode active layer contains less than 1% by weight of polymeric binders disposed in the void spaces.
8 . The apparatus of claim 1 , wherein the electrode active layer is free of polymeric material other than the surface treatment.
9 . The apparatus of claim 1 , wherein the electrode active layer is free of polymeric material.
10 . The apparatus of claim 1 , wherein the surface treatment comprises a material which is soluble in a solvent having a boiling point less than 202° C.
11 . The apparatus of claim 1 , wherein the surface treatment comprises a material which is soluble in a solvent having a boiling point less than 185° C.
12 . The apparatus of claim 1 , wherein during the formation of the active layer, a material forming the surface treatment was dissolved in a solvent having a boiling point less than 202° C.
13 . The apparatus of claim 1 , wherein during the formation of the active layer, a material forming the surface treatment was dissolved in a solvent having a boiling point less than 185° C.
14 . The apparatus of claim 1 , wherein during the formation of the active layer, a material forming the surface treatment was dissolved in a solvent comprising iso-propyl alcohol.
15 . The apparatus of claim 1 , wherein during the formation of the active layer, a material forming the surface treatment was dissolved in a solvent free of pyrrolidone compounds.
16 . The apparatus of claim 1 , wherein the active material particles comprise lithium metal oxide.
17 . The apparatus of claim 16 , wherein the lithium metal oxide is a lithium cobalt oxide, a lithium nickel manganese cobalt oxide, a lithium manganese oxide, a lithium nickel cobalt aluminum oxide a lithium titanate oxide, a lithium iron phosphate oxide, or a lithium nickel cobalt aluminum oxide.
18 . The apparatus of claim 17 , wherein the lithium cobalt oxide is LiCoO 2 , the lithium nickel manganese cobalt oxide is LiNiMnCoO 2 ; the lithium manganese oxide is LiMn 2 O 4 or Li 2 MnO 3 , the lithium nickel cobalt aluminum oxide is LiNiCoAlO 2 , the lithium titanate oxide is Li 4 Ti 5 O 12 , and the lithium iron phosphate oxide is LiFePO 4 .
19 . The apparatus of claim 18 , wherein the LiNiMnCoO 2 is LiNi x Mn y Co 1-x-y , where x is equal to or greater than 0.7 and wherein y is about 0.1.
20 . The apparatus of claim 18 , wherein the LiNiMnCoO 2 is LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , or LiNi 0.6 Mn 0.2 Co 0.2 O 2 .
21 . The apparatus of claim 1 , wherein the surfactant provides functional groups which promote adhesion of the active material particles to the network.