Crosslinked electrolyte capacitors and methods of making the same

• US 5,153,820 A
• Filed: 11/26/1991
• Issued: 10/06/1992
• Est. Priority Date: 04/30/1987
• Status: Expired due to Term

• Current Assignee: Telectronics Pacing Systems, Inc (Abbott Laboratories Incorporated)
• Original Assignee: Specialised Conductives Pty Limited
• Inventors: MacFarlane, Douglas R., Tetaz, John R., Philpott, Arthur K.
• Primary Examiner(s): GRIFFIN, DONALD
• Application Number:
  US07/798,640
• Time in Patent Office: 315 Days
• Field of Search: 361/523, 361/525, 361/526, 361/527, 29/25.03
• US Class Current: 361/525
• CPC Class Codes: H01B 1/122 Ionic conductors
• CPC Class Codes: H01G 11/56 Solid electrolytes, e.g. gels; Additives therein
• CPC Class Codes: H01G 9/012 specially adapted for solid capacitors
• CPC Class Codes: H01G 9/022 Electrolytes; Absorbents
• CPC Class Codes: H01G 9/025 Solid electrolytes H01G11/54 takes precedence
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

Compact leak-proof electrolytic capacitors including, between the anode and the cathode, an ultrathin layer of a solid electrolyte, are disclosed. The solid electrolyte comprises a solid solution of (a) an alkali metal salt, a transition metal salt, an ammonium salt, an organic ammonium salt, a zinc salt, a cadmium salt, a mercury salt or a thallium salt of (b) a monbasic, dibasic or tribasic acid other than a haloid acid (c) in a polymer of high solvation power. Preferred salts are the tetrafluoroborates and hexafluoroglutarates of sodium and potassium, and the preferred polymer is a blend of polyethylene oxide with a siloxane-alkylene oxide copolymer. Crosslinking of the polymer is accomplished by using an agent which may be a di -, tri, or polyisocyanate, a multifunctional reagent which is an analogy of the compound to be crosslinked or di - and multifunctional acids, or di - and multifunctional amines. Methods of making such capacitors are also disclosed. Rolled solid electrolyte capacitors of this type are characterized by low volume, absence of electrolyte leakage, and minimum dielectric deformation, and are capable of delivering intense bursts of current on demand, thereby being suitable for use in biomedical electronic devices such as cardiac pacemakers and defibrillators implanted in the human body.

Claims

1. A compact electrolytic capacitor including an electrically conductive anode, an electrically conductive cathode, and an electrolyte between said anode and said cathode;

characterized in that the electrolyte is in the form of an ultrathin layer of a solution of (a) at least one salt selected from the group consisting of alkali metal salts, transition metal salts, ammonium salts, organic ammonium salts, zinc salts, cadmium salts, mercury salts and thallium salts of (b) at least one acid selected from the group consisting of monobasic, dibasic and tribasic acids other than haloid acids (c) in an ionically conductive carrier of high solvation power.

2. A compact electrolytic capacitor including an electrically conductive anode, an electrically conductive cathode, and an electrolyte between said anode and said cathode;

characterized in that the electrolyte is in the form of an ultrathin layer of a solution of (a) at least one salt selected from the group consisting of alkali metals salts, transition metal salts, ammonium salts, organic ammonium salts, zinc salts, cadmium salts, mercury salts and thallium salts of (b) at least one acid selected from the group consisting of monobasic, dibasic and tribasic acids other and haloid acids (c) in a carrier of high solvation power;

said capacitor having a breakdown voltage which is increased by at least five percent for a given construction due to action of said electrolyte.

3. A compact electrolytic capacitor including an electrically conductive anode, an electrically conductive cathode, and an electrolyte between said anode and said cathode;

characterized in that the electrolyte is in the form of an ultrathin layer of a solution of (a) at lease one salt selected form the group consisting of alkali metal salts, transition metal salts, ammonium salts, organic ammonium salts, zinc salts, cadmium salts, mercury salts and thallium salts of (b) at least one acid selected from the group consisting of monobasic, dibasic and tribasic acids other than haloid acids (c) in a carrier of high solvation power;

said capacitor having a capacitance which is increased by at least five percent for a given anode construction due to action of said electrolyte.

4. A compact electrolytic capacitor including an electrically conductive anode, an electrically conductive cathode, and an electrolyte between said anode and said cathode;

characterized in that the electrolyte is in the form of an ultrathin layer of a solution of (a) at lease one salt selected from the group consisting of alkali metal salts, transition metal salts, ammonium salts, organic ammonium salts, zinc salts, cadmium salts, mercury salts and thallium salts of (b) at least one acid selected form the group consisting of monobasic, dibasic and tribasic acids other than haloid acids (c) in a carrier of high solvation power;

said capacitor undergoing, under given elevated temperature and time conditions, only minimal deforming of its dielectric layer.

5. The capacitor of claim 4, wherein said elevated temperature is 60°

C. and said deforming is less than substantially four percent.

6. The capacitor of claim 5, wherein said deforming takes place over a time of at least 1,000 hours.