Significantly Enhanced Thermoelectric Performance of γ-In2Se3 through Lithiation via Chemical Diffusion

4 years ago

Significantly Enhanced Thermoelectric Performance of γ-In2Se3 through Lithiation via Chemical Diffusion

Zhiliang Song, Jiaolin Cui, Yimin Chao, Gang Chen, Zhengliang Du, Hua Peng

γ-In₂Se₃ is selected as a thermoelectric candidate because it has a unique crystal structure and thermal stability at relatively high temperatures. In this work, we have prepared lithiated γ-In₂Se₃ through chemical diffusion and investigated its band structures and thermoelectric performance. After lithiation of γ-In₂Se₃ in a lithium acetate (CH₃COOLi) solution at 50 °C for 30 h, we have observed a high Hall carrier concentration (n_H) of ≤1.71 × 10¹⁸ cm^–3 at room temperature, which is ∼4 orders of magnitude higher than that of pristine γ-In₂Se₃. The enhancement of n_H is directly responsible for the remarkable improvement in electrical conductivity and can be elucidated as the Fermi level (F_r) unpinning and moving toward the conduction band through the dominant interstitial occupation of Li⁺ in the γ-In₂Se₃ lattice. Combined with the minimum lattice thermal conductivity (κ_L = 0.30–0.34 W K^–1 m^–1) at ∼923 K, the highest ZT value of 0.62–0.67 is attained, which is approximately 9–10 times that of pristine γ-In₂Se₃, proving that the lithiation in γ-In₂Se₃ is an effective approach to the improvement in thermoelectric performance.

Publisher URL: http://dx.doi.org/10.1021/acs.chemmater.7b02467

DOI: 10.1021/acs.chemmater.7b02467