Fabrication of self-standing Si–TiO2 web-nanowired anodes for high volumetric capacity lithium ion microbatteries

Abstract

Abstract Silicon nanowire has been perceived as one of the most promising anodes in the next generation lithium-ion batteries (LIBs) due to its superior theoretical capacity. However, its high-cost and complicated fabrication process presents significant challenges for practical applications. Herein, we propose a simple scalable process, thermal-alkaline treatment followed by sputtering deposition, for preparing a unique self-standing anode of three-dimensional (3D) porous Si–TiO2 web-nanowired nanostructure for micro-LIBs. One-step thermal-alkaline synthesis of TiO2 nanowire scaffolds (TNS) with well-controlled thickness of 600–800 nm is reproducibly obtained onto Cu foils, achieving a 3D porous geometry for further growing Si active materials onto it to form 3D web-nanowired TiO2-Si composite material with interstitial voids. Profiting from the coverage of Si, direct contact of active materials on current collector, and the unique 3D web-nanowired structure, it exhibits high reversible volumetric charge capacity of 2296 mAh cm−3 with a coulombic efficiency of ∼95%, higher capacity retention, better capacity recovery ability and improved rate capability. Importantly, this work paves a simple way to directly build reliable 3D nanostructures or nanowired frameworks on selected current collectors as self-standing anodes for high volumetric capacity microbatteries; thus it is easy to scale up and beneficial for microelectronics industry.