| Autor: |
Lin TC; Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States., Dawson A; Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States., King SC; Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States., Yan Y; Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States., Ashby DS; Department of Materials Science and Engineering, UCLA, Los Angeles, California 90095, United States., Mazzetti JA; Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States., Dunn BS; Department of Materials Science and Engineering, UCLA, Los Angeles, California 90095, United States.; The California NanoSystems Institute, UCLA, Los Angeles, California 90095, United States., Weker JN; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Tolbert SH; Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States.; Department of Materials Science and Engineering, UCLA, Los Angeles, California 90095, United States.; The California NanoSystems Institute, UCLA, Los Angeles, California 90095, United States. |
| Abstrakt: |
Tin-based alloying anodes are exciting due to their high energy density. Unfortunately, these materials pulverize after repetitive cycling due to the large volume expansion during lithiation and delithiation; both nanostructuring and intermetallic formation can help alleviate this structural damage. Here, these ideas are combined in nanoporous antimony-tin (NP-SbSn) powders, synthesized by a simple and scalable selective-etching method. The NP-SbSn exhibits bimodal porosity that facilitates electrolyte diffusion; those void spaces, combined with the presence of two metals that alloy with lithium at different potentials, further provide a buffer against volume change. This stabilizes the structure to give NP-SbSn good cycle life (595 mAh/g after 100 cycles with 93% capacity retention). Operando transmission X-ray microscopy (TXM) showed that during cycling NP-SbSn expands by only 60% in area and then contracts back nearly to its original size with no physical disintegration. The pores shrink during lithiation as the pore walls expand into the pore space and then relax back to their initial size during delithiation with almost no degradation. Importantly, the pores remained open even in the fully lithiated state, and structures are in good physical condition after the 36th cycle. The results of this work should thus be useful for designing nanoscale structures in alloying anodes. |
