Alkaline cell with improved cathode
First Claim
1. An electrochemical cell comprising an anode, an aqueous alkaline electrolyte, and a cathode comprising manganese dioxide and graphite material, wherein said graphite material comprises graphitized carbon fibers having an average BET surface area of between 10 and 60 m2/g.
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Abstract
An alkaline electrochemical cell having a cathode comprising manganese dioxide and conductive graphitized mesophase pitch-based carbon fibers having an increased BET surface area of between about 10 and 60 m2/g, desirably between about 10 and 50 m2/g, preferably between about 30 and 50 m2/g by heat treatment between 800 and 1200° C. with potassium hydroxide. The treated graphitized mesophase pitch-based carbon fibers can comprise between about 1 and 100 percent by weight of the total graphite material in the cathode, typically between about 5 and 50 percent by weight of the total graphite. The total graphite in the cathode desirably comprises between about 4 and 10 percent by weight of the cathode. The graphite can be the mixtures of the graphitized mesophase pitch-based carbon fibers with flaky crystalline graphites including expanded graphites. The graphitized mesophase pitch-based carbon fibers have a mean average diameter typically between about 1 and 10 micron. The use of said carbon fibers in the cathode increases cathode conductivity and results in improved cell performance.
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Citations
29 Claims
- 1. An electrochemical cell comprising an anode, an aqueous alkaline electrolyte, and a cathode comprising manganese dioxide and graphite material, wherein said graphite material comprises graphitized carbon fibers having an average BET surface area of between 10 and 60 m2/g.
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21. An electrochemical cell comprising an anode, an aqueous alkaline electrolyte, and a cathode comprising manganese dioxide and graphite material, wherein said graphite material comprises graphitized mesophase pitch-based carbon fibers having an average BET surface area of between 10 and 60 m2/g.
- 22. An electrochemical cell comprising an anode, an aqueous alkaline electrolyte, and a cathode comprising manganese dioxide and graphite material, wherein said graphite material comprises graphitized mesophase pitch-based carbon fibers having an average BET surface area of between 10 and 50 m2/g.
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24. An electrochemical cell comprising an anode, an aqueous alkaline electrolyte, and a cathode comprising manganese dioxide and graphite material, wherein said graphite material comprises graphitized mesophase pitch-based carbon fibers having an average BET surface area of between 30 and 50 m2/g.
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26. An electrochemical cell comprising an anode, an aqueous alkaline electrolyte, and a cathode comprising manganese dioxide and graphite material, wherein said graphite material comprises graphitized carbon fibers having an average BET surface area of between 10 and 60 m2/g and wherein said carbon fibers have a crystalline size Lc in the crystal “
- c”
direction of between 50 and 300 Angstrom and a crystalline size La in the crystal “
a”
direction of between 100 to 300 Angstrom. - View Dependent Claims (27, 28, 29)
- c”
Specification