Step cell

Claim 2

An electrochemical cell which exhibits a general step change in output voltage at a predetermined discharge level from a first substantially constant voltage to a second substantially constant voltage, and comprising: an alkali metal anode; an electrolyte including an oxyhalide cathode depolarizer together with a Lewis acid and a Lewis base and; a cathode structure of catalytic material suitable for providing oxyhalide-reducing sites, the quantity of electrolyte being proportioned relative to the remaining electrochemically active cell components so as to be the first exhausted.

Claim 3

The cell of claim 1 wherein the cathode structure includes a plurality of pores of sufficient size to generally prevent clogging of the pores by discharge products at the intended cell discharge rate.

Claim 4

The cell of claim 2 wherein the alkali metal is lithium.

Claim 5

The cell of claim 3 wherein the oxyhalide is thionyl chloride.

Claim 6

The cell of claim 4 wherein the Lewis base is aluminum chloride.

Claim 7

The cell of claim 5 wherein the cell active components are present in the approximate ratio of 250 mg carbon to 250 mg of lithium to 2.3 g of electrolyte.

Claim 8

An electrochemical cell which exhibits a generally stepped transition from a first substantially constant voltage to a second substantially constant voltage at a predetermined level of cell discharge and comprising an alkali metal anode, a first electrolyte including a Lewis acid and a Lewis base together with an oxyhalide cathode depolarizer which complexes with a byproduct of cell discharge; and a cathode structure of material capable of providing catalytic sites for the chemical reduction of the oxyhalide, the depolarizer being present in such quantity that it is exhausted prior to the alkali metal and being thereafter extracted from the complex at the second voltage level.

Claim 9

An electrochemical cell which exhibits a generally stepped transition from a first substantially constant voltage to a second substantially constant voltage at a predetermined level of cell discharge and comprising an alkali metal anode, a first electrolyte including a Lewis acid and a Lewis base together with an oxyhalide cathode depolarizer which complexes with a byproduct of cell discharge; and a cathode structure of material capable of providing catalytic sites for the chemical reduction of the oxyhalide, the depolarizer being present in such quantity that it is exhausted prior to the alkali metal and being thereafter extracted from the complex at the second voltage level.

Claim 10

An electrolyte-limited electrochemical cell which exhibits a generally stepped transition from a first substantially constant voltage to a second substantially constant voltage at a predetermined level of cell discharge and comprising a lithium anode; an electrolyte including thionyl chloride cathode depolarizer together with a selected one of a Lewis acid and a Lewis base, the volume of electrolyte being proportioned relative to the amount of lithium so that the electrolyte is the first exhausted element; and a porous carbon cathode structure, the pores of which are sufficiently large to substantially preclude deterioration of cell performance at the intended cell discharge rate, which deterioration is induced by the clogging of the pores by discharge products.

Claim 11

An electrolyte-limited electrochemical cell which exhibits a generally stepped transition from a first substantially constant voltage to a second substantially constant voltage at a predetermined level of cell discharge and comprising a lithium anode; an electrolyte including thionyl chloride cathode depolarizer together with a selected one of a Lewis acid and a Lewis base, the volume of electrolyte being proportioned relative to the amount of lithium so that the electrolyte is the first exhausted element; and a porous carbon cathode structure, the pores of which are sufficiently large to substantially preclude deterioration of cell performance at the intended cell discharge rate, which deterioration is induced by the clogging of the pores by discharge products.

Claim 14

The method of claim 9 including the steps of (a) inserting a quantity of lithium into the cell housing, (b) inserting a porous carbon cathode structure into the cell housing, (c) inserting an electrically insulative and porous seperator between the lithium and carbon, and (d) adding a quantity of electrolyte which includes thionyl chloride as a depolarizer.

Claim 15

The method of claim 10 including the step of limiting the relative amount of electrolyte to approximately 250 mg. carbon to 250 mg. lithium to 2.3 grams of electrolyte.

Claim 16

The method of claim 11 including the step of using an electrolyte containing approximately 1.8 moles of an equimolar ratio of lithium chloride and aluminum chloride per liter of electrolyte.