Transport properties and lithium insertion study in the p-type semi-conductors AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2}
- Department of Chemistry and Materials Research Center, Northwestern University, Evanston, IL 60208-3113 (United States)
- Instituto de Ciencia de Materiales de Barcelona, CSIC, Campus UAB, 08193 Bellaterra, Barcelona (Spain)
The transport properties and lithium insertion mechanism into the first mixed valence silver-copper oxide AgCuO{sub 2} and the B-site mixed magnetic delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} were investigated by means of four probes DC measurements combined with thermopower measurements and in situ XRD investigations. AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} display p-type conductivity with Seebeck coefficient of Q=+2.46 and +78.83 {mu}V/K and conductivity values of {sigma}=3.2x10{sup -1} and 1.8x10{sup -4} S/cm, respectively. The high conductivity together with the low Seebeck coefficient of AgCuO{sub 2} is explained as a result of the mixed valence state between Ag and Cu sites. The electrochemically assisted lithium insertion into AgCuO{sub 2} shows a solid solution domain between x=0 and 0.8Li{sup +} followed by a plateau nearby 1.7 V (vs. Li{sup +}/Li) entailing the reduction of silver to silver metal accordingly to a displacement reaction. During the solid solution, a rapid structure amorphization was observed. The delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} also exhibits Li{sup +}/Ag{sup +} displacement reaction in a comparable potential range than AgCuO{sub 2}; however, with a prior narrow solid solution domain and a less rapid amorphization process. AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} provide a discharge gravimetric capacity of 265 and 230 mA h/g above 1.5 V (vs. Li{sup +}/Li), respectively, with no evidence of a new defined phases. - Graphical abstract: Investigation on the transport properties of AgCuO{sub 2} and the new B-site mixed Delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} shows a p-type conductivity of {sigma}=3.2x10{sup -1} and 1.8x10{sup -4} S/cm, respectively. The high conductivity, as a result from a high charge carrier density in AgCuO{sub 2} supports the existence of a mixed valence state between silver and copper. A particular emphasis is also placed on the electrochemical lithium insertion properties into these two materials by in situ XRD measurements to better insight on the Li{sup +} insertion mechanism and also scrutinize possible new compounds electrochemically accessible in the Li-Ag-Cu system.
- OSTI ID:
- 21212202
- Journal Information:
- Journal of Solid State Chemistry, Vol. 182, Issue 2; Other Information: DOI: 10.1016/j.jssc.2008.10.038; PII: S0022-4596(08)00526-4; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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