Manganese dioxide cathode for a rechargeable alkaline cell, and cell containing the same
First Claim
1. A rechargeable electrochemical cell having a container, internal components comprising an anode, a separator, a manganese dioxide cathode, an ion conductive electrolyte, and a closure member;
- wherein said closure member is placed over said anode, separator, cathode, and electrolyte, within said container, so as to seal said internal components within said container; and
wherein said cathode is restricted from significantly changing its dimensions during cycling by interference at its outer periphery and its bottom with said container, and otherwise by interference with at least one of said separator and said closure member.
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Abstract
This invention relates to rechargeable manganese dioxide cells (usually alkaline cells with zinc anodes or cells having non-aqueous electrolyte and lithium anodes), and particularly to the cathodes therefor. In keeping with the present invention, the cathodes are essentially unconstrained--that is, no cage is used in the cell between the cathodes and the anodes. The cathode is restricted from significantly changing its dimensions during discharge of the cell, when it is inclined to swell--as opposed to the tendency of the cathode to contract during a charge cycle. The cathode substantially fills the entire space alloted for it within the cell, with a slight accommodation for height-wise or longitudinal expansion or growth of the cathode of bobbin-type cells, or cross-wise expansion or growth of button-type cells. There may be additives in the cathode mix, including particularly conductive fibres of graphite or other conductive materials; and other materials may also be added to the cathode mix, including metallic additives. Methods of manufacture are also provided by the present invention, including compaction and recompaction of the cathode pellet, and a range of compaction pressure is suggested. Cells in keeping with the present invention are capable of exhibiting high current drain rates, and long cycle life.
47 Citations
23 Claims
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1. A rechargeable electrochemical cell having a container, internal components comprising an anode, a separator, a manganese dioxide cathode, an ion conductive electrolyte, and a closure member;
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wherein said closure member is placed over said anode, separator, cathode, and electrolyte, within said container, so as to seal said internal components within said container; and wherein said cathode is restricted from significantly changing its dimensions during cycling by interference at its outer periphery and its bottom with said container, and otherwise by interference with at least one of said separator and said closure member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. The rechargeable alkaline electrochemical cell having a container, internal components comprising an anode, a separator, a manganese dioxide cathode, an alkaline electrolyte, and a closure member;
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wherein said closure member is placed over said anode, separator, cathode, and electrolyte, within said container, so as to seal said internal components within said container; wherein said cathode contains from about 4% to about 8% by weight thereof of said alkaline electrolyte, and optionally from about 5% to about 15% by weight thereof of graphite, and optionally from about 0.1% to about 10.0% by weight thereof of conductive carbon; wherein said cathode further contains from about 0.1% to about 5.0% by weight thereof of conductive fibres chosen from the group consisting of carbon fibres, graphite fibres, carbon fibres plated with nickel, carbon fibres plated with silver, graphite fibres plated with nickel, graphite fibres plated with silver, copper fibres plated with nickel, and copper fibres plated with silver; and wherein said cathode optionally further contains from about 1.0% to about 5.0% by weight thereof of a metal-based additive chosen from the group consisting of zinc, zinc, oxide, and zinc stearate.
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23. A rechargeable alkaline electrochemical cell having a container, internal components comprising an anode, a separator, a manganese dioxide cathode, an alkaline electrolyte, and a closure member;
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wherein said closure member is placed over said anode, separator, cathode, and electrolyte, within said container, so as to seal with internal components within said container; wherein said cathode contains from about 4% to about 8% by weight thereof of said alkaline electrolyte, and optionally from about 5% to about 15% by weight thereof of graphite, and optionally from about 0.1% to about 10.0% by weight thereof of conductive carbon; wherein said cathode further contains from about 1.0% to about 5.0% by weight thereof of a metal-based additive chosen from the group consisting of zinc, zinc oxide, and zinc stearate; and wherein said cathode optionally further contains from about 0.1% to about 5.0% by weight thereof of conductive fibres chosen from the group consisting of carbon fibres, graphite fibres, carbon fibres plated with nickel, carbon fibres plated with silver, graphite fibres plated with nickel, graphite fibres plated with silver, copper fibres plated with nickel, and copper fibres plated with silver.
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Specification