Vertically orientated one-dimensional titania lepidocrocite quasi nanoflakes for stabilized lithium deposition in lithium metal anodes

Abstract

Lithium metal has long been considered the ideal anode for a variety of cell chemistries owing to its quite high gravimetric capacity. Dendrite growth, loss of Li in SEI, and processing challenges, however, restrict its practical deployment. Here, a new form of titania, TiO₂, viz. 1-dimensional lepidocrocite (1DL) are used as the basis for creating a Li scaffold. The basic units are Ti–O chains – 5 × 7 Ų in cross-section – that can assemble into quasi 2D nanoflakes. These nanoflakes are synthesized via a bottom-up reaction, directly from commercial 3D-bulk solids at near ambient temperatures and pressures. Here the 2D flakes are vertically oriented to guide Li-metal deposition and serve as a Li metal scaffold. This is achieved through a directional control freezing of an aqueous blade cast slurry. The vertical-1DLs (V-1DL) enable Li nucleation at lower overpotentials compared with bare copper or a conventional cast slurry of 1DL. Their long-range order and vertical alignment contribute to improved Li-ion fluxes. V-1DLs also show improved cyclability with plating and stripping at 2 mAh cm⁻² and 2 mA cm⁻², up to 150 h. Dead Li measurements further indicate that V-1DL reduces Li loss to dead Li.