Vertically aligned architecture in the dense and thick TiO2-graphene nanosheet electrode towards high volumetric and areal capacities

Abstract 2D nanomaterials have attracted intensive attention in the area of compact energy storage owing to their large packing densities. However, the highly tortuous and lengthy channels in conventional 2D nanomaterial electrodes cause sluggish ion diffusion kinetics and seriously reduce the capacity. Herein, we report a simple method adopting diamond wire saw cutting technology to construct a compact vertically aligned TiO2-graphene nanosheet electrode (VATiO2-G) with a large thickness of 130 μm. The vertical alignment not only provides short and less tortuous ion transport pathways to facilitate ion diffusion kinetics, but also improves the electronic conductivity to promote electron transport across the electrode. Accordingly, the VATiO2-G anode for lithium-ion batteries simultaneously exhibits high volumetric and areal capacities of 243 mA h cm−3 and 3.16 mA h cm−2 at 2.8 mA cm−2, respectively. This work exploits a general method to attain vertically aligned architecture in dense and thick 2D nanomaterial electrodes.