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

Abstract

Nanoarchitected Cu−Si core−shell lattices were fabricated via two-photon lithography and tested as mechanically robust Li-ion battery electrodes which accommodate ∼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.

Mechanical Metamaterials and Their Engineering Applications

“…Other potential applications of mechanical metamaterials which makes use of its topological flexibility, size effects, and material constituents includes the creation of architected thermal heat exchangers and insulators, photonic crystals with unique optical properties, phononic crystals with tailorable bandgaps for acoustic cloaking, battery electrodes with optimized topology for electron transport, electrochemical and mechanical properties, and bio‐scaffolds or meta‐biomaterials, which involves the rational design of an optimized combination of mechanical, mass transport and biological properties to enhance tissue regeneration . Recently, microlattices for tunable electromagnetic shielding has also been reported …”

“…Electroplating is then employed to fill in the mold with a metal such as Cu. The polymer is subsequently etched away and the resulting metal structure is coated with a thin layer of another material to form the composite structure (e.g., by Plasma‐Enhanced Chemical Vapor Deposition (PECVD)) . b) The polymer scaffold is synthesized.…”

Design, Fabrication, and Mechanics of 3D Micro‐/Nanolattices

“…By adopting advanced electroplating techniques such as voltage pulsing, metals can be deposited into complicated 3D shapes. For the fabrication of architected materials, a negative template is first established on an electrically conductive substrate, followed by electroplating and removing the template, leaving a solid object …”

Optimized Porous Si/SiC Composite Spheres as High‐Performance Anode Material for Lithium‐Ion Batteries

“…To overcome these problems, researchers have adopted a number of measures such as designing nano‐sized structure (nanoparticles, nanofilms, nanowires and nanotubes) and porous structure, combining Si with carbon,, alloying Si with other metals, and so on. Among these methods, reserving pore and combining buffer materials are the most effective ways to solve the problem of volume expansion during the cycles.…”

“…[9][10][11][12] However, the practical applications of Si anodes are severely hampered by its huge volume change during the alloying/dealloying process, which lead to rapid capacity loss in the continuous charge/discharge processes. [13][14][15] To overcome these problems, researchers have adopted a number of measures such as designing nano-sized structure (nanoparticles, nanofilms, nanowires and nanotubes) [16][17][18][19] and porous structure, [20] combining Si with carbon, [21,22] alloying Si with other metals [23,24] and so on. Among these methods, reserving pore and combining buffer materials are the most effective ways to solve the problem of volume expansion during the cycles.…”