Nanostructured Ge and GeSn films by high-pressure He plasma sputtering for high-capacity Li ion battery anodes

Giichiro Uchida,Yumiko Ikebe,Junki Hayashi,Ryota Narishige,Kenta Nagai,Masaharu Shiratani,Yuichi Setsuhara,Yuma Habu,Mineo Hiramatsu,Naho Itagaki

doi:10.1038/s41598-022-05579-z

Giichiro Uchida, Yumiko Ikebe + Show 8 more

Open Access

https://doi.org/10.1038/s41598-022-05579-z

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Abstract

We fabricated nanostructured Ge and GeSn films using He radio-frequency magnetron plasma sputtering deposition. Monodisperse amorphous Ge and GeSn nanoparticles of 30–40 nm size were arranged without aggregation by off-axis sputtering deposition in the high He-gas-pressure range of 0.1 Torr. The Ge film porosity was over 30%. We tested the charge/discharge cycle performance of Li-ion batteries with nanostructured Ge and GeSn anodes. The Ge anode with a dispersed arrangement of nanoparticles showed a Li-storage capacity of 565 mAh/g after the 60th cycle. The capacity retention was markedly improved by the addition of 3 at% Sn in Ge anode. The GeSn anode (3 at% Sn) achieved a higher capacity of 1128 mAh/g after 60 cycles with 92% capacity retention. Precise control of the nano-morphology and electrical characteristics by a single step procedure using low temperature plasma is effective for stable cycling of high-capacity Ge anodes.

Highlights

We fabricated nanostructured Ge and GeSn films using He radio-frequency magnetron plasma sputtering deposition
We focus on Ge as a Li-ion battery anode material, for which the room temperature diffusivity of Li is 400 and 40 times higher than that for Si and Sn, r espectively[12,23,24,25], and the intrinsic electrical conductivity σ is the order of 1 S/m which is four orders of magnitude higher than that of Si at room temperature of 1 0−4 S/m
Lee et al reported that amorphous Ge nanoparticles, which were produced by a G eCl4 chemical solution process, exhibited high Li-storage capacity over 1450 mAh/g after 19 cycles[11]

Summary

Introduction

We fabricated nanostructured Ge and GeSn films using He radio-frequency magnetron plasma sputtering deposition. A Li ion battery cell with a Si-nanowire-array anode showed 0.25 mAh/cm−2 with a low capacity fading of 16.7% after 20 charge/discharge cycles.

Results

Conclusion