Wilson Greatbatch Ltd.

Wilson Greatbatch Technologies, Inc.

Greatbatch Ltd.

W. Greatbatch Ltd.

Randolph A Leising

Esther S Takeuchi

Marcus J Palazzo

Hong Gan

Amy C Marschilok

Jingsi Yang

An electrochemical cell comprising an electrode, whether it is the cathode of a primary cell or an anode or a cathode of a secondary cell, comprised of a mixture of a robust, high temperature binder along with a sacrificial decomposable polymer is described. The robust binder remains in the electrode throughout formation and processing, and maintains adhesion and cohesion of the cathode during utilization. The sacrificial decomposable polymer is present during the electrode formation stage. However, it is decomposed via a controlled treatment prior to electrode utilization. Upon subsequent high pressure pressing, the void spaces formerly occupied by the sacrificial polymer provides sites where the electrode active material collapses into a tightly compressed mass with enhanced particle-to-particle contact between the active material particles. For a cathode in a primary cell, for example a Li/SVO cell, the result is believed to be improved rate capability, capacity and stability throughout discharge.

Electrochemical cell electrode with improved particle-to-particle contact and method of manufacturing

An electrochemical cell comprising a lithium anode and a fluorinated silver vanadium oxide cathode activated with a nonaqueous electrolyte is described. The fluorinated silver vanadium oxide is of the formula AgVOF, wherein x ranges from about 0.02 to about 0.3.

Method of making silver vanadium oxyfluorides for nonaqueous lithium electrochemical cells

The prevention of lithium clusters from bridging between the negative and positive portions of a cell during discharge is described. This is done by limiting the amount of electrolyte in the cell, thereby eliminating excess electrolyte pooling above the cell stack. It is in this excess electrolyte that a relatively higher Liion concentration can occur, creating an anodically polarized region resulting in the reduction of lithium ions on the negative and positive surfaces as the concentration gradient is relaxed. Typically, a lithium ion concentration gradient sufficient to cause lithium cluster formation is induced by the high rate, intermittent discharge of a lithium/silver vanadium oxide (Li/SVO) cell.

Prevention of lithium deposition in nonaqueous electrolyte cells by electrolyte-to-cathode weight ratio

An improved cathode material for nonaqueous electrolyte lithium electrochemical cell is described. The preferred active material is &#x3b5;-phase silver vanadium oxide (AgVO) coated with a protective layer of a metal oxide, preferably &#x3b3;-phase SVO (AgVO). The SVO core provides high capacity and rate capability while the protective coating reduces reactivity of the active particles with electrolyte to improve the long-term stability of the cathode.

Silver vanadium oxide provided with a metal oxide coating

The current invention relates to the preparation of an improved cathode active material for non-aqueous lithium electrochemical cell. In particular, the cathode active material comprises &#x3b5;-phase silver vanadium oxide prepared by using a &#x3b3;-phase silver vanadium oxide starting material. The reaction of &#x3b3;-phase SVO with a silver salt produces the novel &#x3b5;-phase SVO possessing a lower surface area than &#x3b5;-phase SVO produced from vanadium oxide (VO) and a similar silver salt as starting materials. Consequently, the low surface area &#x3b5;-phase SVO material provides an advantage in greater long-term stability in pulse dischargeable cells.

Preparation of copper silver vanadium oxide from &#x3b3;-phase SVO starting material

It is known that reforming implantable defibrillator capacitors at least partially restores and preserves their charging efficiency. An industry-recognized standard is to reform implantable capacitors by pulse discharging the connected electrochemical cell about once every three months throughout the useful life of the medical device. A Li/SVO cell typically powers such devices. The present invention relates to methodologies for significantly minimizing, if not entirely eliminating, the occurrence of voltage delay and irreversible Rdc growth in the about 35% to 70% DOD region by subjecting Li/SVO cells to novel discharge regimes. At the same time, the connected capacitors in the cardiac defibrillator are reformed to maintain them at their rated breakdown voltages.

Electrochemical treatment method to reduce voltage delay and cell resistance in lithium/silver vanadium oxide cells

The current invention provides a method of preparing a cathode material in a sequential two-part reaction process. In the first step, silver nitrate and vanadium oxide are decomposed by heat under an inert atmosphere. In the second part of the process, the resulting intermediate material is heat treated under an oxidizing atmosphere. The sequential combination of steps produces a highly crystalline silver vanadium oxide cathode material which has properties not heretofore exhibited by SVO prepared by prior art methods.

Preparation for a cathode material by a two-step reduction/oxidation synthesis process

The invention is directed to an SVO electrochemical cell having high rate capability. The cathode is produced by coating a mixture of an active material, conductive additives, a mixed binder, and an aluminum foil current collector. The mixed binder consists of a mixture of heat treated polyamic acid with PVDF. The use of heat treated polyamic acid maintains adhesion to the conductive current collector while the PVDF portion of the binder gives flexibility. A particularly preferred couple is of a lithium/silver vanadium oxide (Li/SVO) chemistry and the binder mixture enables an active slurry of SVO to be coated onto a current collector without delamination.

Electrochemical cell having an electrode of silver vanadium oxide coated to a current collector

The current invention relates to the preparation of an improved cathode active material for non-aqueous lithium electrochemical cell. In particular, the cathode active material comprises &egr;-phase silver vanadium oxide prepared by using a &ggr;-phase silver vanadium oxide starting material. The reaction of &ggr;-phase SVO with a silver salt produces the novel &egr;-phase SVO possessing a lower surface area than &egr;-phase SVO produced from vanadium oxide (V O ) and a similar silver salt as starting materials. Consequently, the low surface area &egr;-phase SVO material provides an advantage in greater long term stability in pulse dischargeable cells.

Preparation of &egr;-phase silver vanadium oxide from &ggr;-phase SVO starting material

The negative electrode or anode for a secondary electrochemical cell comprising a mixture of graphite or &ldquo;hairy carbon&rdquo; and a lithiated metal oxide, a lithiated mixed metal oxide or a lithiated metal sulfide, and preferably a lithiated metal vanadium oxide, is described. A most preferred formulation is graphite mixed with lithiated silver vanadium oxide or lithiated copper silver vanadium oxide.

Anode for nonaqueous secondary electrochemical cells

An electrochemical cell comprising an anode of a Group IA metal and a cathode of a mixed phase metal oxide prepared from a combination of starting materials comprising vanadium oxide and a mixture of at least one of a decomposable silver-containing constituent and a decomposable copper-containing constituent is described. The starting materials are mixed together to form a homogeneous admixture that is not further mixed once decomposition heating begins. The resulting cathode material is particularly useful for implantable medical applications.

Electrochemical cell having a cathode of a mixed phase metal oxide and method of preparation

An electrochernical cell comprising an anode of a Group IA metal and a cathode of a mixed phase metal oxide prepared from a combination of starting materials comprising vanadium oxide and a mixture of at least one of a decomposable silver-containing constituent and a decomposable copper-containing constituent is described. The starting materials are mixed together to form a homogeneous admixture that is not further mixed once decomposition heating begins. The resulting cathode material is particularly useful for implantable medical applications.

Method for providing a cathode of a mixed phase metal oxide

A single phase silver vanadium oxide prepared from a mixture of a decomposable silver salt and vanadium oxide first heated at about 2&deg; C. to about 40&deg; C. above the decomposition temperature of the mixture followed by a second heating in a temperature range of about 490&deg; C. to about 520&deg; C. is described. The silver vanadium oxide material is coupled with a lithium anode and activated with a nonaquecus electrolyte to provide an improved high energy density electrochemical cell having increased pulse voltages and a reduction in voltage delay.

Synthetic method for preparation of a low surface area, single phase silver vanadium oxide

The present invention is related to an electrochemical cell comprising an anode of a Group IA metal and a cathode of a mixed phase metal oxide prepared from a combination of starting materials comprising vanadium oxide and a mixture of at least one of a decomposable silver-containing constituent and a decomposable copper-containing constituent. The starting materials are mixed together to form a homogeneous admixture that is not further mixed once decomposition heating begins to form the product active material. The present cathode material is particularly useful for implantable medical applications.

Mixed phase metal oxide and method of preparation

The present invention is directed to a process for preparing a cathode active material consisting of a single phase of mixed metal oxide, such as a single phase silver vanadium oxide. The synthesis technique involves first heating the starting materials to melt a decomposable starting constituent. This first heating temperature is held for a period of time sufficient to enable the decomposable starting constituent to melt and completely flow throughout and within the other starting materials. Then, the thusly produced melt impregnated reaction admixture is preferably ground to ensure complete homogeneity of the starting materials, followed by heating to the decomposition temperature of the decomposable starting constituent. To finish the synthesis, the decomposed admixture is heated to an elevated temperature above the decomposition temperature to provide the single phase mixed metal oxide.

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Williamsville, NY, United States of America

Randolph A Leising