Tungsten oxide nanorod architectures as 3D anodes in binder-free lithium-ion batteries

Abstract

Tungsten oxide nanorods were synthesized using a template assisted process. A polycarbonate membrane (pore diameter 100 nm) was vacuum infiltrated by an aqueous solution of ammonium paratungstate ((NH₄)₁₀H₂W₁₂O₄₂·xH₂O) and yielded crystalline 3D oriented WO₃ nanorod arrays after template etching and calcination. By coating the nanorod arrays with carbon, a binder-free 3D WO₃/C composite electrode could be fabricated, allowing capacities up to 1149, 811, 699, 559 and 253 mA h g⁻¹ for cycles 1, 2, 20, 50 and 200 as well as a coulombic efficiency of around 99%. Moreover, as prepared WO₃ nanorod structures without that specific type of carbon coating deliver capacities in a range of 200–250 mA h g⁻¹ after 20 cycles. Finally, a full cell lithium ion battery system is fabricated. It consists of LiCoO₂ nanoparticles as cathode and binder-free carbon coated 3D WO₃ composite material as anode. Pre-lithiation of this 3D WO₃/C composite material as pre-conditioning before full cell assembly leads to a cell capacity of almost twice of that without pre-lithiation. Discharge capacities of 111, 91, 41 and 23 mA h g⁻¹ can be obtained for cycles 2, 20, 100 and 200 with a coulombic efficiency of around 99% in the case of the pre-lithiated 3D WO₃/C composite anode.