Abstract
Germanium thin film electrodes show a reversible Na-ion reaction at potentials around 0.15/0.6 V. The reaction is accompanied with a reversible capacity close to 350 mAh g-1, which matches the value expected for the formation of NaGe. The electrode capacity retention is stable over 15 cycles but subsequently declines. However, using fluoroethylene carbonate (FEC) electrolyte additive positively improves capacity retention and promotes the formation of a thinner SEI. Mechanical degradation due to repeated expansion/shrinkage coupled with SEI formation are the main sources of capacity decline. Preliminary XRD results do not reveal the formation of crystalline phases at full (dis)charge. The excellent charge rateup to 340 C highlights the high potential of nanosized germanium as Na-ion anode.
| Original language | English |
|---|---|
| Pages (from-to) | 41-44 |
| Number of pages | 4 |
| Journal | Electrochemistry Communications |
| Volume | 34 |
| DOIs | |
| State | Published - 2013 |
Funding
This work was supported by the U.S. Department of Energy (DOE), Basic Energy Sciences (BES), Materials Sciences and Engineering Division . Microscopy supported by ORNL's Shared Research Equipment (ShaRE) User Program and XRD conducted at SNS and the Center for Nanophase Materials Sciences are both sponsored at ORNL by the Office of BES, U.S. DOE.
Keywords
- Amorphous bulk structure (XRD)
- FEC electrolyte additive improves cycle life
- Germanium (Ge) sputtered thin films
- Sodium-ion (Na-ion) anode
- Very high rate performance