Editing Wilson Greatbatch (section)

== The Greatbatch lithium-iodide battery cell ==
{{unreferenced section|date=September 2011}}
In 1968, [[Catalyst Research Corporation]] of [[Baltimore, Maryland]] developed and patented a [[lithium battery]] cell {{US patent|4049890}}. The cell used two elements at near ends of the [[electrochemical]] scale, causing a high [[voltage]] of 2.8V and an energy density near the physical maximum. Unfortunately, it had an internal [[Electrical impedance|impedance]] which limited its current load to under 0.1 mA and was thus considered useless.

Greatbatch sought to introduce this invention into the pacemaker industry, which could readily use a high impedance battery. The early work was conducted in a rented area of the former [[Wurlitzer]] [[North Tonawanda Barrel Organ Factory|Organ Factory]] in [[North Tonawanda, New York]]. [[Ralph Mead]] is understood to have headed the early electrochemical development.

Greatbatch introduced the developed ''WG1'' cell to [[Artificial pacemaker|pacemaker]] developers in 1971, and was met with limited enthusiasm. On July 9, 1974, Manuel A. Villafaña and [[Anthony Adducci]] founders of [[Cardiac Pacemakers Inc.]]([[Guidant]]) in St. Paul, Minnesota, manufactured the world's first pacemaker with a lithium anode and a lithium-iodide electrolyte solid-state battery.<ref>{{cite web|title=Metal-enclosed cardiac pacer with solid-state power source|url=https://patents.google.com/patent/US3822707?oq=3822707}}</ref><ref>{{cite web|title=Pioneers of the Medical Device Industry|url=http://www.mnhs.org/collections/medTech/org_cardiac_pacemakers.php|publisher=Minnesota Historical Society}}</ref> The lithium-iodide cell manufactured by Greatbatch is now the standard cell for pacemakers, having the [[energy density]], low self-discharge, small size and reliability needed.

In the cell as developed for cardiac pacemaker application, the [[anode]] is [[lithium]] and the [[cathode]] a proprietary composition of [[iodine]] and poly-2-vinylpyridine, neither of which is electrically conductive. However, after processing by mixing and heating to ~ 150&nbsp;°C for 72 hours the components react with each other to form an electrically conductive viscous liquid which, while still molten, is poured into the cell where it cools to form a solid. When the liquid contacts the lithium anode it creates a monomolecular layer of semiconducting crystalline lithium iodide. As the cell is discharged by the current load of the pacemaker, the reaction between the lithium anode and iodine cathode forms a growing barrier of lithium iodide, This is [[resistive]], and causes the terminal voltage of the cell to decrease approximately as an inverse function of the volume of the barrier. Pacemaker designers use this characteristic to permit detection of incipient 'end of life' of the pacemaker's lithium cell.