Germanium as a Sodium Ion Battery Material: In Situ TEM Reveals Fast Sodiation Kinetics with High Capacity

Journal Article · Fri Jan 29 04:00:00 EST 2016 · Chemistry of Materials

DOI:https://doi.org/10.1021/acs.chemmater.6b00200· OSTI ID:1243193

Lu, Xiaotang; Adkins, Emily R.; He, Yang; Zhong, Li; Luo, Langli; Mao, Scott X.; Wang, Chong M.; Korgel, Brian A.

Amorphous germanium (a-Ge) nanowires have great potential for application as anodes in Na-ion batteries. However, the Na-Ge reaction is much less studied and understood compared with other metal alloy anodes. Here, in situ transmission electron microscopy (TEM) is used to study the sodiation/desodiation behavior of a-Ge nanowires. Unexpectedly, our experiments revealed that a-Ge nanowires can be charged at a very fast rate and the final sodiation product, with over 300% volume expansion, is close to Na3Ge instead of NaGe which was considered as the ultimate sodiation state that Ge could achieve. Porous structure was observed in desodiation and, in contrast to delithiation, Na extraction is more likely to create pores in the nanowires due to the much larger radius of the Na ion. This porous structure has demonstrated excellent robustness upon cycling: it could recover flawlessly from the giant pores that were created during experimentation. These results show that the potential of a-Ge for Na-ion battery applications may have been previously underestimated.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1243193
• Report Number(s): PNNL-SA-111277; 48266; KP1704020
• Journal Information: Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 4 Vol. 28; ISSN 0897-4756
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory
amorphous
germanium nanowire
in situ TEM
sodium-ion batteries