Morphological control of nanostructured Ge films in high Ar-gas-pressure plasma sputtering process for Li ion batteries

• Published in: Japanese Journal of Applied Physics 2022-01, Vol.61 (SA), p.SA1002
• Main Authors: Hayashi, Junki, Nagai, Kenta, Habu, Yuma, Ikebe, Yumiko, Hiramatsu, Mineo, Narishige, Ryota, Itagaki, Naho, Shiratani, Masaharu, Setsuhara, Yuichi, Uchida, Giichiro
• Format: Article
• Language: English
• Subjects: Anode effect; Discharge; Gas pressure; Ge semiconductor; Li-ion battery; Lithium-ion batteries; Morphology; Nanostructure; nanostructure film; Plasma sputtering; Porosity; Rechargeable batteries; Sputtering
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/ac2b7b

We present a study on morphological control of nanostructured Ge films by the Ar gas pressure in plasma sputtering deposition. In the low Ar-gas-pressure range, aggregated islands of amorphous grains are formed on the film surface, while in the high-pressure range of 500 mTorr monodisperse nano-grains of about 30 nm in size are orderly arranged without aggregation. The film porosity shows a high value of over 10%. We tested the charge/discharge cycle performance of Li-ion batteries with nanostructured Ge films as anodes. The battery cell with an ordered arrangement structure maintained a high capacity of 434 mAh g −1 after 40 charge/discharge cycles, while that with an aggregated structure exhibited a rapid degradation of capacity to 5.08–183 mAh g −1 . An ordered arrangement of Ge nano-grains with a high porosity, which is realized in a simple one-step procedure using high Ar-gas-pressure plasma sputtering, is effective for the stable cycling of high-capacity metal anodes.