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Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2

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Title: Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2
Authors: Motohashi, T. Browse this author
Sugimoto, Y. Browse this author
Masubuchi, Y. Browse this author
Sasagawa, T. Browse this author
Koshibae, W. Browse this author
Tohyama, T. Browse this author
Yamauchi, H. Browse this author
Kikkawa, S. Browse this author
Issue Date: 15-May-2011
Publisher: American Physical Society
Journal Title: Physical Review B
Volume: 83
Issue: 19
Start Page: 195128
Publisher DOI: 10.1103/PhysRevB.83.195128
Abstract: Thermoelectric properties of the layered cobalt oxide system LixCoO2 were investigated in a wide range of Li compositions, 0.98 ≥ x ≥ 0.35. Single-phase bulk samples of LixCoO2 were successfully obtained through electrochemical deintercalation of Li from the pristine LiCoO2 phase. While LixCoO2 with x ≥ 0.94 is semiconductive, the highly Li-deficient phase (0.75 ≥ x ≥ 0.35) exhibits metallic conductivity. The magnitude of the Seebeck coefficient at 293 K (S293K) significantly depends on the Li content (x). The S293K value is as large as +70 up to +100μV/K for x ≥ 0.94, and it rapidly decreases from +90μV/K to +10μV/K as x is lowered within a Li composition range of 0.75 ≥ x ≥ 0.50. This behavior is in sharp contrast to the results of x ≤ 0.40 for which the S293K value is small and independent of x (+10μV/K), indicating that a discontinuous change in the thermoelectric characteristics takes place at x = 0.40-0.50. The unusually large Seebeck coefficient and metallic conductivity are found to coexist in a narrow range of Li composition at about x = 0.75. The coexistence, which leads to an enhanced thermoelectric power factor, may be attributed to unusual electronic structure of the two-dimensional CoO2 block.
Rights: ©2011 American Physical Society
Type: article
URI: http://hdl.handle.net/2115/45609
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 本橋 輝樹

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