Stabilization of Nanoporous Si/Graphite Composite Anodes by Ultrathin Titanicone Coatings

Abstract

Herein, we report on the stabilization of nanostructured Si/graphite based anodes for Li-ion batteries (LIB) with titanicone against capacity fade and solid electrode interphase (SEI) formation. Nanostructured Si powders were first prepared by optimized and tailored Metal Assisted Catalytic Etching (MACE) of p-type Si wafers. These nanopowders were subsequently coated with titanicone thin films using Molecular Layer Deposition (MLD) and extensively characterized in reference to uncoated nanopowders. The LIB anode slurry was prepared by blending 18 wt. % uncoated or titanicone-coated Si nanopowder with graphite. The electrochemical performance of the anode containing coated Si was benchmarked against a corresponding electrode containing uncoated Si nanopowder. The titanicone-coated anode exhibited less reduction of the original capacity upon long-term cycling than the anode composed of graphite and uncoated Si nanopowder (51.1% versus 89.1%). The titanicone-coated Si anode also exhibited higher electrochemical activity during cyclic voltammetry measurements. The results demonstrate the power of ultrathin metalcone - in particular, titanicone – coatings for the improvement of the capacity and cyclability of Si/graphite based anodes.