title: Ionic conduction in Zn3(PO4)2.4H2O enables efficient discharge of the zinc anode in serum.
abstract: Batteries contain corrosive or reactive components necessitating containment in a case, setting a limit to their miniaturization. Miniature, small-capacity batteries could power medical sensors in the body, for example sensing glucose for diabetes management. A miniature, case-less Zn-Ag/AgCl battery would consist merely of a zinc anode and a bioinert gel-coated Ag/AgCl cathode, if both operated efficiently in the interstitial fluid. Such a battery has not previously been built, primarily because of rapid corrosion of Zn. We show that the corrosion of zinc is significantly reduced by growth of Zn2+-ion-conducting, O2-impermeable, hopeite [Zn3(PO4)2.4H2O] lamellae on the Nafion-coated Zn anode. The hopeite lamellae allow discharge of the Zn anodes over three weeks at 86% current efficiency in physiological buffer and at 60% efficiency over two weeks in serum. The Zn|physiological buffer|Ag/AgCl cell operates at 1.00 V at 13 muA cm-2 and at 0.94 V at 0.2 mA cm-2 anodic current density.
authors.affiliation: Department of Chemistry, Sogang University, Seoul 121-742, Korea. shinws@sogang.ac.kr
authors.forename: Woonsup
authors.initials: W
authors.lastname: Shin
authors.forename: Junghyun
authors.initials: J
authors.lastname: Lee
authors.forename: Yousung
authors.initials: Y
authors.lastname: Kim
authors.forename: Hugo
authors.initials: H
authors.lastname: Steinfink
authors.forename: Adam
authors.initials: A
authors.lastname: Heller
mesh_terms: D004553:Electric Conductivity; D004566:Electrodes; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010710:Phosphates / Q000737:chemistry*; D016062:Porosity; D044967:Serum / Q000737:chemistry*; D013997:Time Factors; D015032:Zinc / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D010710:Phosphates; D017967:Zinc Compounds; C043952:zinc phosphate; D015032:Zinc