Abstract
Fast charging remains one of the greatest safety challenges in Li-ion batteries due to Li-dendrite growth occurring on graphite anodes if they are lithiated too quickly. The search for high-rate anodes has highlighted materials in the Wadsley-Roth (WR) shear phase family. The relative abundance of V compared with traditional WR compositions of Nb and W makes V-based phases attractive. However, the high voltage and poor reversibility typically associated with V redox have made V-rich WR phases less studied than Nb- and W-rich phases. Here, we show that a new V-rich Wadsley-Roth phase, V7Nb6O29, achieves excellent rate capability and 80% capacity retention after 228 cycles with a relatively low average voltage of 1.76 V vs Li/Li+ compared with other V-rich WR phases. Single-crystal X-ray diffraction reveals a P4/m space group with repeating 2 × 2 × ∞ and 3 × 3 × ∞ blocks of V4+ and Nb5+ octahedra. Combined neutron pair distribution function analysis, X-ray absorption spectroscopy, and density functional theory calculations show that V redox is the primary source of capacity and that cycling stability is provided by the stable octahedral coordination adopted by V4+ in the material.
| Original language | English |
|---|---|
| Pages (from-to) | 3470-3483 |
| Number of pages | 14 |
| Journal | Chemistry of Materials |
| Volume | 35 |
| Issue number | 9 |
| DOIs | |
| State | Published - May 9 2023 |
Funding
This work was supported by the NSF Career Award (DMR-2145832). NPDF experiments used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. E.L., J.B., and H.J. also acknowledge the startup support from the University of Utah. The participation of H.A. and T.D.S. was supported by the NSF QII-TAQS grant number 1936383 and was partially funded by the Kuwait Foundation for the Advancement of Sciences (KFAS) under project code \u201CCB20-68EO-01\u201D. The participation of A.H. was supported by the NSF ReUSE REU site at the University of Utah under NSF Award 1950589. The single-crystal synthesis, structural solution, and the contributions of M.A.D. and J.M.A. were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, EPSCoR, and Neutron Scattering Sciences under award DE-SC0018174. They also thank NSF CHE MRI 1828078 and the University of Alabama for the purchase of the single-crystal X-ray diffraction instrument used in this study. This work made use of the University of Utah shared facilities of the Micron Technology Foundation Inc. Microscopy Suite sponsored by the College of Engineering, Health Sciences Center, Office of the Vice President for Research, and the Utah Science Technology and Research (USTAR) initiative of the State of Utah.