title: Realizing the full potential of insertion anodes for Mg-ion batteries through the nanostructuring of Sn.
abstract: Magnesium is of great interest as a replacement for lithium in next-generation ion-transfer batteries but Mg-metal anodes currently face critical challenges related to the formation of passivating layers during Mg-plating/stripping and anode-electrolyte-cathode incompatibilities. Alternative anode materials have the potential to greatly extend the spectrum of suitable electrolyte chemistries but must be systematically tailored for effective Mg(2+) storage. Using analytical (scanning) transmission electron microscopy ((S)TEM) and ab initio modeling, we have investigated Mg(2+) insertion and extraction mechanisms and transformation processes in β-SnSb nanoparticles (NPs), a promising Mg-alloying anode material. During the first several charge-discharge cycles (conditioning), the β-SnSb particles irreversibly transform into a porous network of pure-Sn and Sb-rich subparticles, as Mg ions replace Sn atoms in the SnSb lattice. After electrochemical conditioning, small Sn particles/grains (<33 ± 20 nm) exhibit highly reversible Mg-storage, while the Sb-rich domains suffer substantial Mg trapping and contribute little to the system performance. This result strongly indicates that pure Sn can act as a high-capacity Mg-insertion anode as theoretically predicted, but that its performance is strongly size-dependent, and stable nanoscale Sn morphologies (<40 nm) are needed for superior, reversible Mg-storage and fast system kinetics.
authors.affiliation: Joint Center for Energy Storage Research, Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Lucas R
authors.initials: LR
authors.lastname: Parent
authors.forename: Yingwen
authors.initials: Y
authors.lastname: Cheng
authors.forename: Peter V
authors.initials: PV
authors.lastname: Sushko
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Shao
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Chong-Min
authors.initials: CM
authors.lastname: Wang
authors.forename: Nigel D
authors.initials: ND
authors.lastname: Browning
keywords: Mg-ion battery; STEM EDS; SnSb nanoparticles; ion-insertion anode; multivalent battery; nanostructured Sn; transformation anode