In Situ Lithiation-Delithiation of Mechanically Robust Cu-Si Core-Shell Nanolattices in a Scanning Electron Microscope

Nanoarchitected Cu-Si core-shell lattices were fabricated via two-photon lithography and tested as mechanically robust Li-ion battery electrodes which accommodate similar to 250% Si volume expansion during lithiation. The superior mechanical performance of the nanolattice electrodes is directly observed using an in situ scanning electron microscope, which allows volume expansion and morphological changes to be imaged at multiple length scales, from single lattice beam to the architecture level, during electrochemical testing. Finite element modeling of lithiation-induced volume expansion in a core-shell structure reveals that geometry and plasticity mechanisms play a critical role in preventing damage in the nanolattice electrodes. The two-photon lithography-based fabrication method combined with computational modeling and in situ characterization capabilities would potentially enable the rational design and fast discovery of mechanically robust and kinetically agile electrode materials that independently optimize geometry, feature size, porosity, surface area, and chemical composition, as well as other functional devices in which mechanical and transport phenomena are important.