Understanding Stabilization in Nanoporous Intermetallic Alloy Anodes for Li-Ion Batteries Using Operando Transmission X-ray Microscopy

Abstract

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.

Interface engineering towardhigh‐efficiencyalloy anode for next‐generation energy storage device

“…Peng et al constructed controllable Zn/Si porous multi‐layer films structure to moderate the volume change and decrease the internal stress during lithiation/delithiation process 122 . Tolbert et al fabricated nanoporous antimony−tin (NP‐SbSn) through a facile and scalable selective‐etching method 123 . Furthermore, operando transmission X‐ray microscopy (TXM) was employed to display the porous structure of these NP‐SbSn well retained during cycling, which exhibit significantly better structural stability than the pure Sn.…”

Ultrafine nanoporous intermetallic catalysts by high-temperature liquid metal dealloying for electrochemical hydrogen production

“…Three-dimensional (3D) bicontinuous nanoporous structures fabricated by dealloying 25 , the selective removal of the less stable component(s) from an alloy, are very attractive owing to their large specific surface area with ample surface defects, high electric conductivity, and rapid mass transport pathways 19 , 26 . Several intermetallic compounds have been fabricated or integrated into 3D porous structures by the chemical etching of heterogeneous precursors (such as Mg 2 Cu 27 , PtSi 28 , (Pt 1-x M x ) 3 Al (M = Ni, Co, Fe) 29 – 31 , SbSn 32 , and Pd 3 Bi 24 ) or by segregation as nanoparticulate phases anchored on 3D nanoporous metal frameworks during dealloying (such as Cu 3 Sn/Cu 33 , Co 3 Mo/Cu 10 , Al 7 Cu 4 Ni/Cu 34 , and Nb 5 Si 3 /NbTi 35 ). However, these porous intermetallic materials exhibit low flexibility in microstructural optimization, high electric resistance due to copious grain boundaries and interfaces, and poor mechanical stability.…”

“…, SbSn32 , and Pd 3 Bi 24 ) or by segregation as nanoparticulate phases anchored on 3D nanoporous metal frameworks during dealloying (such as Cu 3 Sn/Cu 33 , Co 3 Mo/Cu 10 , Al 7 Cu 4 Ni/Cu 34 , and Nb 5 Si 3 /NbTi35 …”

Redox Mediated Control of Electrochemical Potential in Liquid Cell Electron Microscopy

“…Electrochemical reactions have enabled several advances in the development of energy storage technologies, photonic devices, nanocrystal synthesis methodologies, and the electrochemical synthesis of commodity chemicals . Structural dynamics that occur during electrochemical reactions are often probed with diffraction or spectroscopic techniques that provide ensemble information, or with microscopy techniques exhibiting microscale spatial resolution, − which limits mechanistic insight at the nanoscale. Although these techniques can be coupled with localized techniques for further insight, methods to probe electrochemical structural dynamics at nanoscale or atomic-scale resolution remain limited.…”