US5047899A — Solid electrolyte capacitor and method of making

Claim 1

Independent Claim 128 words

A method of storing a large amount of backup energy, comprising the steps of: (a) providing a capacitor structure including a solid electrolyte composed of a layer of RbAg 4 I 5 , an anode composed of a layer of carbon and RbAg 4 I 5 adjoining a first surface of the electrolyte, and a cathode composed of a layer of carbon and RbAg 4 I 5 adjoining a second surface of the electrolyte; (b) supplying a current to charge up the anode of the capacitor structure to a voltage in the range from 0.50 volts to 0.66 volts to cause storage of charge in the capacitor structure in both a double layer capacitance mode and a pseudocapacitance mode and to cause silver to deposit in the anode.

Claim 2

Independent Claim 128 words

A method of storing a large amount of backup energy, comprising the steps of: (a) providing a capacitor structure including a solid electrolyte composed of a layer of RbAg 4 I 5 , an anode composed of a layer of carbon and RbAg 4 I 5 adjoining a first surface of the electrolyte, and a cathode composed of a layer of carbon and RbAg 4 I 5 adjoining a second surface of the electrolyte; (b) supplying a current to charge up the anode of the capacitor structure to a voltage in the range from 0.50 volts to 0.66 volts to cause storage of charge in the capacitor structure in both a double layer capacitance mode and a pseudocapacitance mode and to cause silver to deposit in the anode.

Claim 3

Dependent Claim 14 words

The method of claim 1 including supplying the backup voltage to a CMOS memory.

Claim 4

Dependent Claim 127 words

A capacitor structure for storing backup energy, comprising in combination: (a) a layer of solid electrolyte material composed of RbAg 4 I 5 ; (b) a layer of anode material composed of carbon and RbAg 4 I 5 and adjoining a first surface of the electrolyte material, and a layer of cathode material also composed of carbon and RbAg 4 I 5 and adjoining a second surface of the electrolyte material parallel to the first surface; (c) means for charging the capacitor structure to produce a voltage of 0.50 volts to 0.66 volts between the anode material and the cathode material, to thereby cause storage of charge in a double layer mode and also in a pseudocapacitance mode and to cause silver to deposit in the anode.

Claim 5

Dependent Claim 127 words

A capacitor structure for storing backup energy, comprising in combination: (a) a layer of solid electrolyte material composed of RbAg 4 I 5 ; (b) a layer of anode material composed of carbon and RbAg 4 I 5 and adjoining a first surface of the electrolyte material, and a layer of cathode material also composed of carbon and RbAg 4 I 5 and adjoining a second surface of the electrolyte material parallel to the first surface; (c) means for charging the capacitor structure to produce a voltage of 0.50 volts to 0.66 volts between the anode material and the cathode material, to thereby cause storage of charge in a double layer mode and also in a pseudocapacitance mode and to cause silver to deposit in the anode.

Claim 6

Dependent Claim 39 words

The capacitor structure of claim 3 wherein the electrolyte material, the anode material, and the cathode material are compressed together such that solid bonding of the anode material, cathode material, and electrolyte is attained without use of binder material.

Claim 7

Dependent Claim 24 words

The capacitor structure of claim 4 wherein the molecular bonding is produced by compression forces of greater than twenty thousand pounds per square inch.

Claim 8

Dependent Claim 31 words

The capacitor structure of claim 5 wherein the thickness of the layer of anode material, the layer of electrolyte material, and the layer of cathode material each are approximately 50 mils.

Claim 9

Dependent Claim 23 words

The capacitor structure of claim 3 wherein the anode material, cathode material, and electrolyte material are in the form of relatively thin layers.

Claim 10

Dependent Claim 23 words

The capacitor structure of claim 3 wherein the anode material, cathode material, and electrolyte material are in the form of relatively thick layers.

Claim 11

Dependent Claim 42 words

The capacitor structure of claim 3 including a first refractory metal contact coupling an outer surface of the anode material to the charging means, and a second refractory metal contact coupling an outer surface of the cathode material to the charging means.

Claim 12

Dependent Claim 23 words

The capacitor structure of claim 9 wherein the refractory metal is composed of material from the group consisting of titanium, tantalum, and molybdenum.

Claim 13

Dependent Claim 40 words

The capacitor structure of claim 3 including a first electrical contact coupling an outer surface of the anode material to the charging means, and a second electrical contact coupling an outer surface of the cathode material to the charging means.

Claim 14

Dependent Claim 25 words

The capacitor structure of claim 11 wherein the first and second electrical contacts are composed of material from the group consisting of carbon and graphite.

Claim 15

Dependent Claim 41 words

The capacitor structure cf claim 3 including silver plated on an interface between the electrolyte material and the anode material, whereby silver is substantially depleted from the electrolyte material, preventing further growth of dendrites which cause failure of the capacitor structure.

Claim 16

Dependent Claim 58 words

The capacitor structure of claim 13 wherein the layer anode material is formed by charging the anode material to a voltage in the range of 0.50 volts to 0.66 volts, causing dendrites to form on an outside edge of the capacitor structure at an interface between the anode material and the electrolyte material and then removing the dendrites.

Claim 17

Dependent Claim 29 words

The capacitor structure of claim 3 including encapsulation hermetically sealing the layer of anode material, the layer of cathode material, and the layer of electrolyte material from outside environment.

Claim 18

Dependent Claim 53 words

The capacitor structure of claim 3 including a plurality of capacitor structures each including a layer of anode material, a layer of cathode material, and a layer of electrolyte material, connected in series, the charging means charging each of the capacitor structures to an anode-to-cathode voltage difference of 0.50 volts to 0.65 volts.

Claim 19

Independent Claim 189 words

A method of making a capacitor structure, comprising the steps of: (a) forming a first powder mixture of carbon and RbAg 4 I 5 , and forming a second powder mixture of RbAg 4 I 5 ; (b) placing a first amount of the first powder mixture in a die; (c) compressing the first amount in the die to form an anode layer; (d) placing a second amount of the second powder mixture in the die in the anode layer; (e) compressing the second amount against the anode layer in the die to form an electrolyte layer on the anode layer; (f) placing a third amount of the first powder mixture in the die on the electrolyte layer; (g) compressing the third amount against the electrolyte layer in the die to form a cathode layer on the electrolyte layer; (h) compressing the anode, electrolyte, and cathode layers together in the die by applying compressive pressure greater than twenty thousand pounds per square inch to form a solid pellet; and (i) forming first and second refractory metal contacts that adjoin outer surfaces of the anode layer and cathode layer, respectively.

Claim 20

Independent Claim 189 words

A method of making a capacitor structure, comprising the steps of: (a) forming a first powder mixture of carbon and RbAg 4 I 5 , and forming a second powder mixture of RbAg 4 I 5 ; (b) placing a first amount of the first powder mixture in a die; (c) compressing the first amount in the die to form an anode layer; (d) placing a second amount of the second powder mixture in the die in the anode layer; (e) compressing the second amount against the anode layer in the die to form an electrolyte layer on the anode layer; (f) placing a third amount of the first powder mixture in the die on the electrolyte layer; (g) compressing the third amount against the electrolyte layer in the die to form a cathode layer on the electrolyte layer; (h) compressing the anode, electrolyte, and cathode layers together in the die by applying compressive pressure greater than twenty thousand pounds per square inch to form a solid pellet; and (i) forming first and second refractory metal contacts that adjoin outer surfaces of the anode layer and cathode layer, respectively.

Claim 21

Dependent Claim 27 words

The method of claim 17 including forming the first powder mixture by mixing 1 part of carbon with 9 equal parts of RbAg 4 I 5 .

Claim 22

Dependent Claim 27 words

The method of claim 17 wherein the compressing of steps (c), (e), and (g) includes applying compressive forces of greater than twenty thousand pounds per square inch.

Claim 23

Dependent Claim 17 words

The method of claim 17 wherein steps (a) through (i) are performed in an oxygen-free, moisture-free environment.

Claim 24

Dependent Claim 36 words

The method of claim 17 wherein the first powder mixture is formed by melting the carbon and RbAg 4 I 5 , cooling the melt, and grinding it into particles of about one mil in size.

Claim 25

Dependent Claim 34 words

The method of claim 21 wherein the second powder mixture is formed by melting the RbAg 4 I 5 , cooling the melt, and grinding it into particles of about one mil in size.

Claim 26

Dependent Claim 51 words

The method of claim 17 including causing a DC charging current to flow into the cathode layer to charge the cathode layer of the capacitor structure to a voltage above 0.50 volts relative to the anode layer for a sufficiently long time to cause silver to form in the anode layer.

Claim 27

Dependent Claim 51 words

The method of claim 23 including repeatedly discharging the cathode layer and then recharging the cathode layer to voltages in the range from 0.50 volts to 0.65 volts for a sufficiently long time to cause peripheral silver dendrites to grow around an interface between the anode layer and the electrolyte layer.

Claim 28

Dependent Claim 24 words

The method of claim 24 including continuing the discharging and recharging until peripheral silver dendrite growth has essentially stopped and then removing the dendrites.

Claim 29

Independent Claim 149 words

A method of supplying standby power for a semiconductor memory, comprising the steps of: (a) providing a capacitor structure including a solid electrolyte composed of a layer of RbAg 4 I 5 , an anode composed of a layer of carbon and RbAg 4 I 5 adjoining a first surface of the electrolyte, and a cathode composed of a layer of carbon and RbAg 4 I 5 adjoining a second surface of the electrolyte; (b) supplying a current to charge up the anode of the capacitor structure to a voltage in the range from 0.50 volts to 0.65 volts to cause storage of charge in the capacitor structure in both a double layer capacitance mode and a pseudocapacitance mode; (c) sensing a condition in which the semiconductor memory requires application of standby power thereto; (d) electrically connecting electrodes of the capacitor structure to power terminals of the CMOS memory.

Claim 30

Independent Claim 149 words

A method of supplying standby power for a semiconductor memory, comprising the steps of: (a) providing a capacitor structure including a solid electrolyte composed of a layer of RbAg 4 I 5 , an anode composed of a layer of carbon and RbAg 4 I 5 adjoining a first surface of the electrolyte, and a cathode composed of a layer of carbon and RbAg 4 I 5 adjoining a second surface of the electrolyte; (b) supplying a current to charge up the anode of the capacitor structure to a voltage in the range from 0.50 volts to 0.65 volts to cause storage of charge in the capacitor structure in both a double layer capacitance mode and a pseudocapacitance mode; (c) sensing a condition in which the semiconductor memory requires application of standby power thereto; (d) electrically connecting electrodes of the capacitor structure to power terminals of the CMOS memory.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-09-09	1995-03-11	1995-09-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-09-09	1999-03-11	1999-09-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-09-09	2003-03-11	2003-09-10	$7700.00	Window Closed / Lapsed

Solid electrolyte capacitor and method of making

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