Lithium iodine battery

The lithium iodine battery (Li-I ₂ battery) is a non-rechargeable lithium battery with lithium as the anode and a combination based on iodine and poly-2-vinylpyridine (P2VP) as the cathode . The solid electrolyte used is lithium iodide , which has the property of being able to conduct lithium ions from the anode to the cathode well, while it is impermeable to iodine ions in the opposite direction. This type of battery is primarily used in electrically operated implants such as cardiac pacemakers as a long-lasting and intrinsically safe energy source. Between the market launch in 1972 and 1997, cardiac pacemakers used 3.5 million lithium-iodine batteries.

properties

Two Li-I ₂ batteries in D-design, as used in cardiac pacemakers

Lithium-iodine batteries are solid-state batteries without liquid components and are characterized by a very low self-discharge of 0.06% per year. The open circuit voltage varies depending on the type and is 2.8 V for commercially available pacemaker cells  . Due to their high internal resistance, the Li-I ₂ cells can only deliver low discharge currents, usual load resistances are over 10  kΩ , the drawable power is under 1  mW . The cells are short-circuit-proof and in no case of operation there will be gas formation in the cell. Leakage of the battery can thus be reliably prevented, which is an essential criterion for implants.

Reactions

The lithium metal releases electrons at the anode. It is oxidized to the lithium ion Li ⁺ , which is absorbed in the LiI solid electrolyte:

Anode reaction: ${\displaystyle \quad \mathrm {Li\rightarrow Li^{+}+e^{-}} }$

Because of the electron release, this is the negative pole of the battery.

The elemental or complex-bound iodine is reduced at the cathode (positive pole), i. That is, it forms iodide anions I ^- with the absorption of electrons . These react with the lithium ions coming through the solid electrolyte to form lithium iodide:

Cathode reaction:     resp.     ${\displaystyle \mathrm {I_{2}+2\ Li^{+}+2\ e^{-}\rightarrow 2\ LiI} }$ ${\displaystyle \mathrm {P2VP\cdot nI_{2}+2\ Li^{+}+2\ e^{-}\rightarrow P2VP\cdot (n-1)\ I_{2}+2\ LiI} }$

Overall reaction:      resp.     ${\displaystyle \mathrm {2\ Li+I_{2}\rightarrow 2\ LiI} }$ ${\displaystyle \mathrm {P2VP\cdot n\ I_{2}+2n\ Li\rightarrow P2VP+2n\ LiI} }$

Historical

The first batteries with a solid iodide electrode were developed by a working group at the Jet Propulsion Laboratory (JPL); they published their results in 1967. However, they did not use a lithium electrode, but mainly magnesium and calcium anodes. The lithium-iodine battery was patented by James Moser and Alan Schneider in 1970/1971.

literature

• Thomas Roy Crompton: Battery Reference Book . Newnes, 2000, ISBN 0-7506-4625-X , chapter 24.

Individual evidence

1. ↑ VS Mallela, V. Ilankumaran, NS Rao: Trends in cardiac pacemaker batteries. In: Indian pacing and electrophysiology journal . tape 4 , no. 4 , 2004, p. 201-212 , PMID 16943934 , PMC 1502062 (free full text).
2. ^ Curtis F. Holmes: The Lithium / Iodine-Polyvinylpyridine Battery - 35 Years of Successful Clinical Use. (PDF) Retrieved August 26, 2014 .  
3. ^ Christian Julien: The CRC Handbook of Solid State Electrochemistry . Ed .: Paul J. Gellings, Henny J. Bouwmeester. CRC Press, Inc., 1997, ISBN 0-8493-8956-9 , Chapter 11: Solid State Batteries, pp. 386 .
4. ^ Edward J. Prosen, Jennifer C. Colbert: A Microcalorimeter for Measuring Self-Discharge of Pacemakers and Pacemaker Power Cells . Ed .: Journal of Research of the National Bureau of Standards. tape 85 , no. 3 , 1980, doi : 10.6028 / jres.085.010 .
5. ^ ^{A b} Felix Gutmann, Allen M. Hermann, Alan Rembaum: Solid State Electrochemical Cells Based on Charge Transfer Complexes . In: Journal of The Electrochemical Society (JEC) . tape 114 , no. 4 . The Electrochemical Society ECS, April 1966, pp. 323-329 , doi : 10.1149 / 1.2426586 ( abstract online ).
6. ↑ Patent US3660163 : Solid State Lithium-Iodine Primary Battery. Applied June 1, 1970 , published May 2, 1972 , applicant: Catalyst Research Corporation, Baltimore, inventor: James R. Moser. ‌
7. ↑ Patent US3674562 : Primary cells and iodine containing cathodes therefor. Applied January 15, 1971 , published July 4, 1972 , Applicant: Catalyst Research Corporation, Baltimore, Inventor: Alan A Schneider, James R Moser. ‌