Biomimetic layer-by-layer Co-mineralization approach towards TiO2/Au nanosheets with high rate performance for lithium ion batteries

Abstract

We fabricated a sandwich-like branched-polyethyleneimine (b-PEI)/TiO₂/Au/graphene oxide (GO) nanocomposite through a biomimetic layer-by-layer co-mineralization approach, and the polymer b-PEI was believed to act as both an inducing agent for the hydrolysis of titanium bis(ammonium lactato)-dihydroxide (Ti-BALDH) and a reducing agent for the reduction of HAuCl₄ in the synthetic procedure. Upon organic pyrolysis in air at 500 °C, a TiO₂/Au nanosheet was formed; and gold nanocrystals were observed uniformly dispersed on TiO₂ nanosheet. Moreover, the obtained TiO₂/Au nanosheets demonstrated an enhanced lithium storage performance when they are used as anode materials for lithium ion batteries (LIBs), particularly, a high capacity of 205 mA h g⁻¹ and 189 mA h g⁻¹ was obtained at 5 C and 10 C rate, respectively, indicating the high rate capability of the material. The greatly improved rate performance might be attributed from both the sheet-like nanostructure and the existence of uniformly dispersed gold nanocrystals, which facilitate electron transfer and lithium ions diffusion in the material. The result suggests that the TiO₂ electrode performance can be improved through a design of sheet-like nanocomposites using a bio-inspired route, which is desirable for both “green synthesis” and application for high power LIBs, moreover, such a benign bio-inspired route can be developed into a general pathway to synthesize many other TiO₂ based nanocomposites for broad applications in the fields of batteries, photoelectrochemistry, photocatalysis and dye-sensitized solar cells.