Organic nitrite additives for nonaqueous electrolyte in alkali metal electrochemical cells

In combination with an implantable medical device requiring at least one current pulse for a medical device operating function, an electrochemical cell which is dischargeable to deliver the current pulse while exhibiting reduced voltage delay, the cell which comprises:

• a) an anode comprising an alkali metal;
• b) a solid cathode of electrically conductive material;
• and
• c) a nonaqueous electrolyte activating the anode and the cathode, the nonaqueous electrolyte comprising:
• i) a first solvent selected from the group consisting of an ester, an ether and a dialkyl carbonate, and mixtures thereof;
• ii) a second solvent selected from the group consisting of a cyclic carbonate, a cyclic ester and a cyclic amide, and mixtures thereof;
• iii) a nitrite additive having the formula:
• (RO)N(.dbd.O), wherein R is an organic group of either a saturated hydrocarbon or heteroatom group containing 1 to 10 carbon atoms or an unsaturated hydrocarbon or heteroatom group containing 2 to 10 carbon atoms;
• and
• iv) an alkali metal salt dissolved therein, wherein the alkali metal of the salt is similar to the alkali metal comprising the anode, and wherein the activated anode and cathode provide the electrochemical cell dischargeable to deliver at least one current pulse for the medical device operating function, wherein the current pulse is of an electrical current of a greater amplitude than that of a prepulse current immediately prior to the pulse.

A method for providing an electrochemical cell activated with a nonaqueous electrolyte, comprising the steps of:

• a) providing an anode comprising an alkali metal;
• b) providing a solid cathode of electrically conductive material;
• and
• c) activating the electrochemical cell with the nonaqueous electrolyte operatively associated with the anode and the cathode, the nonaqueous electrolyte comprising:
• i) a first solvent selected from the group consisting of an ester, an ether and a dialkyl carbonate, and mixtures thereof;
• ii) a second solvent selected from the group consisting of a cyclic carbonate, a cyclic ester and a cyclic amide, and mixtures thereof;
• iii) a nitrite additive having the formula:
• (RO)N(.dbd.O), wherein R is an organic group of either a saturated hydrocarbon and heteroatom group containing 1 to 10 carbon atoms or an unsaturated hydrocarbon or heteroatom group containing 2 to 10 carbon atoms;
• and
• iv) an alkali metal salt dissolved therein, wherein the alkali metal of the salt is similar to the alkali metal comprising the anode.

A method for reducing voltage delay in a pulse discharging electrochemical cell activated with a nonaqueous electrolyte, comprising the steps of:

• a) providing an anode comprising an alkali metal;
• b) providing a cathode including a mixed metal oxide comprised of vanadium oxide and a second metal "SM" selected from the group consisting of Groups IB, IIB, IIIB, IVB, VIB, VIIB and VIII of the Periodic Table of the Elements, the mixed metal oxide having the general formula SM.sub.x V.sub.2 O.sub.y wherein 0.30.ltoreq.x.ltoreq.2.0 and 4.5.ltoreq.y .ltoreq.6.0;
• c) activating the electrochemical cell with the nonaqueous electrolyte operatively associated with the anode and the cathode, the nonaqueous electrolyte comprising:
• i) a first solvent selected from the group consisting of an ester, an ether and a dialkyl carbonate, and mixtures thereof;
• ii) a second solvent selected from the group consisting of a cyclic carbonate, a cyclic ester and a cyclic amide, and mixtures thereof;
• iii) a nitrite additive having the formula:
• (RO)N(.dbd.O), wherein R is an organic group of either a saturated hydrocarbon or heteroatom group containing 1 to 10 carbon atoms or an unsaturated hydrocarbon or heteroatom group containing 2 to 10 carbon atoms;
• and
• iv) an alkali metal salt dissolved therein, wherein the alkali metal of the salt is similar to the alkali metal comprising the anode;
• and
• d) discharge the cell to deliver at least one current pulse of an electrical current of a greater amplitude than that of a prepulse current immediately prior to the pulse.

A method for reducing voltage delay in a pulse discharging electrochemical cell activated with a nonaqueous electrolyte, comprising the steps of:

• a) providing an anode comprising an alkali metal;
• b) providing a cathode including a mixed metal oxide comprised of vanadium oxide and a mixture of copper and a second metal "SM" selected from the group consisting of groups IB, IIB, IIIB, IVB, VIB, VIIB, and VIII of the Periodic Table of the Elements, the mixed metal oxide having the general formula Cu.sub.x SM.sub.y V.sub.2 O.sub.z wherein 0.01 .ltoreq.x.ltoreq.1.0, 0.01.ltoreq.y.ltoreq.1.0 and 5.01.ltoreq.z.ltoreq.6.5;
• c) activating the electrochemical cell with the nonaqueous electrolyte operatively associated with the anode and the cathode, the nonaqueous electrolyte comprising:
• i) a first solvent selected from the group consisting of an ester, an ether and a dialkyl carbonate, and mixtures thereof;
• ii) a second solvent selected from the group consisting of a cyclic carbonate, a cyclic ester and a cyclic amide, and mixtures thereof;
• iii) a nitrite additive having the formula:
• (RO)N(.dbd.O), wherein R is an organic group of either a saturated hydrocarbon or heteroatom group containing 1 to 10 carbon atoms or an unsaturated hydrocarbon or heteroatom group containing 2 to 10 carbon atoms;
• and
• iv) an alkali metal salt dissolved therein, wherein the alkali metal of the salt is similar to the alkali metal comprising the anode;
• and
• d) discharge the cell to deliver at least one current pulse of an electrical current of a greater amplitude than that of a prepulse current immediately prior to the pulse.