Preparation of carbon-coated lithium iron phosphate/titanium nitride for a lithium-ion supercapacitor

Abstract

Carbon-coated lithium iron phosphate (C-LiFePO₄) supported on a titanium nitride (TiN) substrate was designed as the electrode material for a lithium-ion supercapacitor for an energy storage application. C-LiFePO₄ nanoparticles were prepared via a hydrothermal synthesis and carbonization treatment process. TiN nanowires were prepared using an anodization oxidation and nitridization process. A C-LiFePO₄/TiN nanowire network was synthesized by loading C-LiFePO₄ nanoparticles onto TiN nanowires through a chemical bath deposition method. The surface morphology and microstructure of C-LiFePO₄/TiN were characterized using scanning electron microscopy, X-ray diffraction and Raman spectrum analysis. The lithium-ion insertion–extraction behavior of the C-LiFePO₄/TiN in a Li₂SO₄ aqueous electrolyte was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge measurements. C-LiFePO₄/TiN exhibited a high capacitance of 972 F g⁻¹ at the current density of 1.0 A g⁻¹, presenting a capacity improvement of 210% when compared with 314 F g⁻¹ for LiFePO₄/TiN. The C-LiFePO₄/TiN nanowire network also exhibited good cycle stability and high rate capability, presenting a promising application of the lithium-ion supercapacitor.