Chemistry: electrical current producing apparatus – product – and – Having diverse cells or diverse removable cells in a support...
Reexamination Certificate
1999-10-08
2002-09-17
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Having diverse cells or diverse removable cells in a support...
C429S006000, C429S006000, C429S047000
Reexamination Certificate
active
06451463
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
This present invention relates generally to improvements in the field of rechargeable batteries, and more particularly to improvements in metal-air batteries, including metal-air fuel cell battery (FCB) systems which have both discharging and recharging modes of operations.
2. Brief Description of the State of Knowledge in the Art
In recent times, metal-air fuel cell battery (FCB) systems have received great recognition for their ability to produce large amounts of electrical power from relatively small size devices. During power generation, a metal-fuel structure such as zinc is positioned over a cathode structure in the presence of an ionically-conducting medium, such as an electrolyte-impregnated gel or electrolyte solution. In accordance with well known principles of electro-chemistry, as electrical power is produced from the system the metal-fuel structure is oxidized. Examples of prior art metal-air FCB systems are disclosed in Applicants' U.S. Pat. No. 5,250,370 incorporated herein by reference.
In U.S. Pat. No. 5,250,370, Applicant discloses an improved method of and system for recharging oxidized metal-fuel tape used in prior art metal-air FCB systems. During power generation, metal-fuel tape is transported over a stationary cathode structure in the presence of an ionically-conducting medium, such as an electrolyte-impregnated gel. In U.S. Pat. No. 5,250,370, a recharging head is installed downstream from the discharging head for carrying out recharging operations when the metal-fuel tape has been completely oxidized. In order to enable quicker recharging of metal-fuel tape for reuse in FCB discharging operations, the cathode surface of the recharging head is made substantially greater than the cathode surface of the discharging head. While this arrangement allows for recharging of metal fuel tape, it requires a separate recharging head assembly in order to efficiently carry out recharging operations, in an energy efficient manner. This increases the manufacturing cost of the overall system, and containing the head assemblies within a compact housing quite difficult.
In Applicants' U.S. Pat. No. 6,296,960 Applicants disclose a metal-air fuel cell battery system having a hybrid discharging/recharging head assembly for carrying out discharging and recharging operations as required. In this FCB system design, the recharging head assembly is spaced apart from the discharging assembly, for selectively recharging discharged regions of metal fuel tape.
In Applicants' copending U.S. application Ser. No. 09/074,337, Applicants also disclose a FCB power generation system that produces electrical power by discharging metal-fuel having the form factor of cards and sheets. When the metal-fuel cards are discharged (i.e. oxidized), the metal-fuel cards can be recharged by being reduced by a recharging head assembly provided within the system.
However, despite such advances in rechargeable metal-air FCB systems, prior art metal-air FCB systems, in general, suffer from an number of shortcomings and drawbacks that have made commercial success difficult to attain, namely: (1) some systems and devices employ bi-functional cathode structures which are energy-inefficient and have a relatively short cycle life (e.g. about 40 or so recharging cycles) due to the production of gas bubbles inside the porous cathode structure caused by the recharging action; (2) many systems and devices employ separate recharging head assemblies for recharging metal-fuel structures, which increases the manufacturing cost of the overall system, while containing the head assemblies in a compact housing; (3) some systems employ metal-fuel anode structures having large surface areas which are very difficult to discharge in an uniform manner due to the formation of “spots” during recharging operations which provide places for zinc tree-like structures (referred to as “dendrites”) to grow and locations where short-circuiting can occur; (4) some systems and devices employ metal anode structures that undergo significant shape change during recharging operations; (5) some systems and devices employ the electrolyte-pervious metal anode structures from which “dendrites” often grow from towards the cathode structures, eventually shorting-out the power cell structure and thus reducing the cycle life thereof; and (6) some systems and devices employ the metal anode structures that undergo densification during repeated recharging and discharging cycles, thus reducing the cycle life of the power cell structures therewithin as well.
Thus, there is a great need in the fuel-cell battery art for alternative ways and means of electrochemically producing electrical power from metal-air fuel cell battery systems as well as recharging the same as needed, while overcoming the shortcomings and drawbacks of prior art technologies known in the fuel-cell battery field.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, a primary object of the present invention is to provide an improved system and method of discharging and/or recharging electro-chemical battery systems and devices, while avoiding the shortcomings and drawbacks of prior art methodologies.
Another object of the present invention is to provide an improved metal-air FCB system, wherein different types of cathode elements are embodied within an integrated support structure in order to achieve improvements in discharging and/or recharging operations, as well as the overall performance of the electrical power generating systems and devices employing the same.
Another object of the present invention is to provide an integrated cathode structure having a plurality of relatively small cathode elements spatially arranged on a cathode support structure, in combination with a plurality of anode-contacting elements spatially arranged on an anode-contacting element support plate, wherein each cathode element is in spatial registration with one of the anode-contacting elements so as to form either a discharging and/or recharging cell that is independently activatable (i.e. enabled) using a solid-state transistor switching technology under the control of a cell switching controller embodied within an electrical power generating module.
Another object of the present invention is to provide such an integrated cathode structure, wherein control over each cell can be achieved by monitoring the cell voltage and/or current during discharging or recharging operations, and then measuring the voltages and/or currents and comparing the same with reference measures to ensure that a particularly selected power, voltage and/or current control method is being carried out in a desired manner.
Another object of the present invention is to provide such an integrated cathode structure, wherein if any cell has lower than normal voltage value thereacross, then the cell switching controller, can automatically determine (by computation) to skip this section during normal discharge, and after a certain period of time, the cell switching controller can return to recheck the status of the skipped cell and decide to “fix/repair” or abandon the same.
Another object of the present invention is to provide such an integrated cathode structure, wherein thinner current conductors can be used to collect the same amount of current within a discharging head assembly.
Another object of the present invention is to provide such an integrated cathode structure which, when used for recharging metal-fuel like structures, enables the recharging power to be evenly distributed among the cathode elements, or in a manner precisely controlled according to feedback signals derived therewhile, so as to achieve uniform recharging and avoidance of dendrite growth, thereby increasing the anode cycle life.
Another object of the present invention is to provide an improved metal-air FCB system, having a hybrid discharging/recharging head assembly which comprises a first array of cathode elements (i.e. segments) that are a disposed on a common support substrate and optimized/designed for
Faris Sadeg M.
Tsai Tsepin
Crispino Ralph J.
Kalafut Stephen
Perkowski Thomas J.
Reveo Inc.
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