IMPROVED ELECTRODE FOR FLOW BATTERIES
An electrode for a flow battery includes a carbonized felt having a bulk density of from between about 0.05 g/cc and about 0.2 g/cc and a dry weight and an equilibrium weight after submersion in an electrolyte. The carbon felt receives a treatment that enables an equilibrium weight at least 20 times the dry weight.
1 . An electrode for a flow battery comprising:
a carbonized felt having a bulk density of from between about 0.05 g/cc and about 0.2 g/cc and having a dry weight and an equilibrium weight after submersion in an electrolyte, wherein said equilibrium weight is at least 20 times said dry weight.
2 . The electrode according to claim 1 wherein said equilibrium weight is at least 21 times said dry weight.
3 . The electrode according to claim 1 wherein said equilibrium weight is at least 22 times said dry weight.
4 . The electrode according to claim 1 wherein said bulk density is at least about 0.1 g/cc.
5 . The electrode according to claim 1 wherein said carbonized felt is a carbonized rayon fiber material.
6 . The electrode according to claim 1 wherein said carbonized felt is a carbonized PAN fiber material.
7 . The electrode according to claim 1 wherein said carbonized felt is a carbonized pitch fiber material.
8 . The electrode according to claim 1 wherein said carbonized felt is a carbonized lignin fiber material.
9 . An electrode for a flow battery having an electrolyte as a working fluid, the electrode comprising:
a carbonized felt material having a bulk density of from between about 0.05 g/cc and about 0.2 g/cc and wherein a 0.75 cm thick portion of said carbonized felt material submerges under force of gravity in said electrolyte in less than 15 seconds.
10 . The electrode according to claim 9 wherein said bulk density is at least about 0.1 g/cc.
11 . The electrode according to claim 9 wherein said bulk density is at least about 0.15 g/cc.
12 . The electrode according to claim 1 wherein said carbonized felt is a carbonized rayon fiber material.
13 . The electrode according to claim 1 wherein said carbonized felt is a carbonized PAN fiber material.
14 . The electrode according to claim 1 wherein said carbonized felt is a carbonized pitch fiber material.
15 . The electrode according to claim 1 wherein said carbonized felt is a carbonized lignin fiber material.
16 . A method of making an electrode for a flow battery comprising:
providing a carbon felt having a bulk density from between about 0.05 g/cc and about 0.2 g/cc;
exposing said carbon felt to an acid solution; and
heat treating said carbon felt to at least 300 degrees C. for at least 1 hour.
17 . The method of making an electrode according to claim 16 wherein said acid solution comprises an organic acid.
18 . The methods of making an electrode according to claim 17 wherein said organic acid comprises oxalic acid.
19 . The method of making an electrode according to claim 16 wherein said carbon felt has a bulk density from between about 0.06 g/cc and about 0.08 g/cc.
20 . The methods of making an electrode according to claim 16 wherein said carbon felt has a bulk density of at least 0.1 g/cc.
21 . A method of making an electrode according to claim 16 wherein said heat treating step is performed after said step of exposing said carbon felt to an acid solution.