Lithium primary cell
View Patent ↗The present disclosure is directed to a primary electrochemical cell having an improved discharge performance, and/or improved reliability under physical abuse and/or partial discharge. More particularly, the present disclosure is directed to such a primary cell that comprises an improved cathode material comprising iron disulfide and a select pH-modifier and an improved non-aqueous electrolyte that comprises a solvent, a salt, pH-modifiers, and selected organic or inorganic additives, which improve cell stability and discharge performance.
1. A primary electrochemical cell comprising: a cell housing; an anode comprising lithium; a cathode comprising a cathode active material, the cathode active material comprising
iron disulfide;
a separator disposed between the anode and the cathode; and,
a non-aqueous electrolyte in fluid communication with the anode, cathode and separator, wherein said electrolyte comprises a solvent, a salt dissolved therein, and a pH-modifier, wherein said pH-modifier is an inorganic additive selected from the group consisting of ammonium carbonate and ammonium bicarbonate or a combination thereof in an amount from about 0.1% to about 5.0%, by weight of the electrolyte; and wherein the solvent comprises a mixture, by volume, of from about 55% to about 70% dioxolane, from about 30% to about 45% sulfolane and from about 0.1% to about 0.5% of 3,5-dimethylisoxazole.
2. The electrochemical cell of claim 1 , wherein the salt is selected from the group consisting of lithium iodide, lithium nitrate, lithium bis(trifluoromethanesulfonyl) imide and mixtures thereof.
3. The electrochemical cell of claim 1 , wherein the electrolyte has a water content of less than about 50 ppm.
4. The electrochemical cell of claim 1 , wherein the salt comprises from about 0.75 to about 1M of lithium bis(trifluoromethanesulfonyl)imide.
5. The electrochemical cell of claim 1 , wherein the cell further comprises a gasket seal material comprising polypropylene and a copolymer of ethylene-propylene-diene monomer.
6. The electrochemical cell of claim 1 , wherein the cell further comprises a Positive Temperature Coefficient (PTC) device.
7. The electrochemical cell of claim 1 , wherein the salt is lithium nitrate.