Abuse resistant active metal anode/fluid cathode depolarized cells
AssigneeDuracell International Inc.
InventorJoseph N. Barrella
Life of this patent
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Abstract
An abuse resistant electrochemical cell having an active metal anode, a fluid cathode depolarizer, an inert cathode and an electrolyte solution. The cell components are arranged in terms of relative capacities and configuration such that a sufficient amount of the dischargeable anode metal is utilized prior to the cell reaching zero volts (caused by deactivation of the cathode) whereby, upon forced discharge, polarization of both anode and cathode and deep cell reversal occur within a short period of time thereafter. This short period of time is no greater than 15% of the initial discharge time to zero volts. The cell additionally contains sufficient fluid depolarizer such that a portion thereof remains at the time of such deep cell reversal.
Claims28
An abuse resistant electrochemical cell comprising an active metal anode, a fluid cathode depolarizer in a non-aqueous electrolyte solution and an inert cathode, wherein the realizable capacity of said inert cathode, relative to the realizable capacities of said anode and said cathode depolarizer, is dependent upon at least one variable parameter characterized in that under predetermined parameters, which result in said inert cathode being the limiting factor in the life of the cell and said predetermined parameters being selected as approximating abuse conditions, the relationship between the utilizable capacity of the active metal anode and the realizable capacity of the inert cathode is such that at the end of the discharge life of said cell, the quantity of dischargeable active metal remaining in the anode is no greater than about 15% of the amount of active metal already discharged;
- and that there is initially a stoichiometric excess of said cathode depolarizer above the initial amount of said utilizable anode metal.
An abuse resistant electrochemical cell comprising a lithium anode, a fluid sulfur dioxide cathode depolarizer in a non-aqueous electrolyte solution wherein said sulfur dioxide does not exceed 75% by weight of said electrolyte solution and an inert carbonaceous cathode wherein at a discharge rate of at least 2 amperes and an ambient temperature of no more than -30.degree. C., said inert cathode is the limiting factor in the life of said cell, characterized in that at the end of the discharge life of said cell, the quantity of dischargeable lithium remaining in the anode is no greater than about 15% of the amount of lithium already discharged;
- and that there is initially at least a 5% stoichiometric excess of SO.sub.2 above the initial amount of utilizable lithium metal.
An abuse resistant electrochemical cell comprising an active metal anode, a fluid cathode depolarizer in a non-aqueous electrolyte solution and an inert cathode, wherein the realizable capacity of said inert cathode, relative to the realizable capacities of said anode and said cathode depolarizer, is dependent upon at least one variable parameter characterized in that under predetermined parameters, which result in said inert cathode being the limiting factor in the life of said cell and said predetermined parameters being selected as approximating abuse conditions, the relationship between the utilizable capacity of the active metal anode and the realizable capacity of the inert cathode is such that, at the end of cell discharge with said cell being force discharged at a rate substantially equivalent to the initial discharge rate, the time required for anode polarization is no greater than about 15% of the time initially required to reach the end of cell life and wherein at the time of anode polarization there is remaining fluid depolarizer.
Dependencies are inferred from the claim text.