Abstract
Sodium-ion battery (SIB) alloy anodes are attractive for their high gravimetric capacities, but they suffer from sluggish kinetics during charge storage caused by bulk diffusion during (de)sodiation-induced phase transformations. Among these SIB alloy anodes, antimony (Sb) exhibits one of the fastest (de)sodiation kinetics, with a rate capability comparable to that of intercalation electrodes. It is desirable to understand the origin of Sb fast kinetics, and herein, we use ab initio grand canonical Monte Carlo (ai-GCMC) to predict possible intermediate compounds that form during (de)sodiation of Sb and discover a family of layered glassy intermediates that are not only close to the convex hull of the Na-Sb phase diagram, but are also similar in composition, structure, and energy, suggesting that an amorphous phase may be observed during (de)sodiation. Further, we find that the diffusion barrier for Na in an amorphous/glassy phase can be as low as 6 kJ mol−1. To experimentally validate our simulation results, we performed electrochemical studies including cyclic voltammetry (CV)-based kinetics analysis, which revealed a fast intermediate reaction; and operando wide-angle X-ray scattering (WAXS), which showed an alternating crystalline pattern indicative of an amorphous intermediate. Based on our results, we propose the following sodiation pathway: Sb (crystalline) → NaySb (amorphous/glassy) → NaxSb (amorphous/glassy) → Na3Sb (crystalline), where y < 1.5, 1.5 ≤ x ≤ 2, and these amorphous/glassy intermediate phases are responsible for the fast kinetics.
| Original language | English |
|---|---|
| Pages (from-to) | 3671-3681 |
| Number of pages | 11 |
| Journal | Journal of Materials Chemistry A |
| Volume | 12 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jan 8 2024 |
| Externally published | Yes |
Funding
The authors are thankful to the Vagelos Institute for Energy Science and Technology (VIEST) for the financial support through the 2018 VIEST seed grant. This work was carried out in part at the Singh Center for Nanotechnology, part of the National Nanotechnology Coordinated Infrastructure Program, which is supported by the NSF grant NNCI-1542153. T. Q. acknowledges the support of the US Department of Energy, Office of Basic Energy Sciences, under grant DE-SC0019281. A. M. R. acknowledges the support of the Army Research Laboratory via the Collaborative for Hierarchical Agile and Responsive Materials (CHARM) under cooperative agreement W911NF-19-2-0119. The authors acknowledge computational support from the National Energy Research Scientific Computing Center. We gratefully acknowledge the financial support from the National Science Foundation (NSF) through the Future Manufacturing Research Grant (FMRG) with award number 2134715, the MRSEC DMR-1720530, and NSF MRI-1725969. The NSF MRI-1725969 grant was used to acquire the Xenocs Xeuss 2.0 Dual Cu–Mo source and Environmental X-ray Source (DEXS) used in this research.
| Funders | Funder number |
|---|---|
| National Science Foundation | 2134715 |
| National Science Foundation | |
| U.S. Department of Energy | |
| Basic Energy Sciences | DE-SC0019281 |
| Basic Energy Sciences | |
| Army Research Laboratory | W911NF-19-2-0119 |
| Army Research Laboratory | |
| Materials Research Science and Engineering Center, Harvard University | DMR-1720530, MRI-1725969 |
| Materials Research Science and Engineering Center, Harvard University | |
| National Energy Research Scientific Computing Center | |
| Vagelos Institute for Energy Science and Technology, University of Pennsylvania | NNCI-1542153 |
| Vagelos Institute for Energy Science and Technology, University of Pennsylvania |
