Reverse electrodialysis device having enhanced maximum power density with ultra-thin ion exchange membranes
A reverse electrodialysis device, including an anode, a cathode, one or more single cells spaced apart from each other between the anode and the cathode, each single cell including a cation exchange membrane and an anion exchange membrane, and a shielding membrane disposed to define spaces between the anode and the single cell and/or between the cathode and the single cell. The cation exchange membrane and the shielding membrane include a porous polymer substrate and a polymer electrolyte incorporated into pores in the substrate.
1. A reverse electrodialysis device, comprising:
an anode;
a cathode;
one or more single cells spaced apart from each other between the anode and the cathode so as to form a flow path through which fresh water flows, each of the single cells including a cation exchange membrane and an anion exchange membrane spaced apart from each other so as to form a flow path through which sea water flows; and
a shielding membrane disposed so as to define spaces in at least one of a location between the anode and the single cell or a location between the cathode and the single cell,
wherein,
each of the cation exchange membrane and the shielding membrane includes a porous polymer substrate having a pore volume of 30 to 70%, an average pore size of 0.05 μm to 0.1 μm, and a polymer electrolyte impregnating pores in the porous polymer substrate, the pores having inner surfaces which are hydrophilic, the polymer electrolyte being a crosslinked polymer made of (a) a solution including 2-acrylamido-2-methylpropanesulfonic acid, (b) a crosslinking agent comprising (i) a bisacrylamide-based crosslinking agent or (ii) a (meth)acryloyl group- or alkenyl group-substituted triazine, and (c) an initiator, and
the anion exchange membrane includes a porous polymer substrate having a pore volume of 30% to 70%, an average pore size of 0.05 μm to 0.1 μm, and a polymer electrolyte impregnating pores in the porous polymer substrate, the pores having inner surfaces which are hydrophilic, the polymer electrolyte being a crosslinked polymer made of a solution including (vinylbenzyl)trimethylammonium chloride, a crosslinking agent, and an initiator.
2. The reverse electrodialysis device of claim 1 , wherein the porous polymer substrate, included in the cation exchange membrane, is a porous hydrocarbon-based membrane with a thickness of 10 μm to 55 μm.
3. The reverse electrodialysis device of claim 1 , wherein the acrylamide-based crosslinking agent comprises at least one selected from the group consisting of N,N′-ethylenebisacrylamide, N,N′-methylenebisacrylamide, N,N′-methylenebismethacrylamide, and N,N′-bisacryloylpiperazine.
4. The reverse electrodialysis device of claim 1 , wherein the initiator used to form the cation exchange membrane and the shielding membrane is a photoinitiator or a thermal initiator, and the photoinitiator comprises a Doracure series or Irgacure series photoinitiator made by Ciba-Geigy, and the thermal initiator comprises N,N′-azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO).
5. The reverse electrodialysis device of claim 1 , wherein the polymer electrolyte included in the cation exchange membrane and the shielding membrane is formed by subjecting a solution comprising 2-acrylamido-2-methylpropanesulfonic acid and a crosslinking agent at a weight ratio of 2˜9:1 to crosslinking polymerization.
6. The reverse electrodialysis device of claim 1 , wherein the bisacrylamide-based crosslinking agent comprises at least one selected from the group consisting of N,N′-ethylenebisacrylamide, N,N′-methylenebisacrylamide, N,N′-methylenebismethacrylamide, and N,N′-bisacryloylpiperazine.
7. The reverse electrodialysis device of claim 1 , wherein the (meth)acryloyl group-substituted triazine is 1,3,5-triacryloylhexahydro-1,3,5-triazine.
8. The reverse electrodialysis device of claim 1 , wherein the polymer electrolyte included in the anion exchange membrane is formed by subjecting a solution comprising (vinylbenzyl)trimethylammonium chloride and a crosslinking agent at a weight ratio of 4˜12:1 to crosslinking polymerization.