Removal Of Impurities From Lithium-Iron Disulfide Electrochemical Cells
A lithium electrochemical cell, and a process for making the same, are disclosed. The cell includes a chelating agent that is specifically selected to remove impurities introduced to the cell by other component.
1 . A primary electrochemical cell:
an anode;
a cathode including an active material having a maximum potential versus lithium that is less 2.8 volts and a nominal operating voltage of 1.5 volts or less; and
a liquid electrolyte comprising a chelating agent capable of sequestering at least one metal ion impurity present within the cell.
2 . The electrochemical cell according to claim 1 , wherein the chelating agent remains soluble in the liquid electrolyte after the at least one metal ion impurity is sequestered by the chelating agent.
3 . The electrochemical cell according to claim 1 , wherein the chelating agent comprises a polychelatogen.
4 . The electrochemical cell according to claim 1 , wherein the chelating agent is selected from the group consisting of: poly(ethyl acrylate/acrylic acid), derivatives of poly(ethyl acrylate/acrylic acid), diphenylthiocarbazone, derivatives of diphenylthiocarbazone, poly(acrylamide/acrylic acid), poly(methyl methacrylate/methacrylic acid), poly(n-butyl acrylate/acrylic acid), poly(ethylene/acrylic acid), poly(butadiene/maleic acid), ethylenediaminetetra-acetic acid, diphenylthiocarbazone, phenothioazine and carboxymethylcellulose.
5 . The electrochemical cell according to claim 1 , wherein the metal ion impurity is selected from the consisting of: zinc ions, ferric ions, ferrous ions and copper ions.
6 . The electrochemical cell according to claim 5 , wherein the anode consists essentially of lithium or a lithium alloy and the cathode includes iron disulfide.
7 . The electrochemical cell according to claim 1 , wherein the anode consists essentially of lithium or a lithium alloy and the cathode comprises iron disulfide.
8 . The electrochemical cell according to claim 7 , wherein the chelating agent comprises a polychelatogen.
9 . The electrochemical cell according to claim 7 , wherein the chelating agent is selected from the group consisting of: poly(ethyl acrylate/acrylic acid), derivatives of poly(ethyl acrylate/acrylic acid), diphenylthiocarbazone, derivatives of diphenylthiocarbazone, poly(acrylamide/acrylic acid), poly(methyl methacrylate/methacrylic acid), poly(n-butyl acrylate/acrylic acid), poly(ethylene/acrylic acid), poly(butadiene/maleic acid), ethylenediaminetetra-acetic acid, diphenylthiocarbazone, phenothioazine and carboxymethylcellulose.
10 . The electrochemical cell according to claim 7 , wherein the chelating agent remains soluble in the liquid electrolyte after the at least one metal ion impurity is sequestered by the chelating agent.