Self‐Healing, Ga‐Sb Alloy Confined Sn Anode for Stable Na‐Ion Storage in Glyme Based Electrolytes
Dimpal Deori, Madhurja Buragohain, Youhyun Son, Sooraj Kunnikuruvan, Ashok Kumar Nanjundan, Philipp Adelhelm, Thangavelu Palaniselvam
Abstract
Abstract In this contribution, the development of a self‐healable GaSb alloy featuring a confined Sn (core‐shell) structure is reported for stable Na + storage in an ether‐based electrolyte. The core‐shell architecture of GaSb@Sn has been validated through high‐angle annular dark field‐scanning transmission electron microscopy (HAADF‐STEM) paired with electron energy loss spectroscopy (EELS) analysis. The GaSb@Sn support on carbon electrode has delivered specific capacity of 560 mAh g electrode −1 at 50 mA g −1 with 89% retention capacity after 1200 cycles and specific capacity of 449 mAh g electrode −1 at 2 Ag −1 with 82% retention capacity after 2000 cycles. The GaSb@Sn/C electrode stores Na + by forming Na‐Sn, Na‐Sb‐O, and Na‐Ga‐O intermetallic compounds, as confirmed by operando XRD studies. Operando electrochemical dilatometry studies reveal that the self‐healable electrode expands by 33% at the electrode level during Na + insertion, significantly lower than the theoretically predicted expansion of Sn, which is 420%. DFT calculations show that the adsorption of diglyme on GaSb@Sn (−0.4 eV) is weaker than that on bulk Sn (−5.1 eV). The weaker interaction between diglyme and GaSb@Sn could be responsible for the thinner SEI formation on the edges of GaSb@Sn, thereby resulting in the high initial coulombic efficiency (GaSb@Sn‐ 81%, Bulk Sn‐62%) and stable cycle life.