화학공학소재연구정보센터
Electrochimica Acta, Vol.162, 275-281, 2015
Atomic layer deposition of amorphous iron phosphates on carbon nanotubes as cathode materials for lithium-ion batteries
A non-aqueous approach was developed to synthesize iron phosphate cathode materials by the atomic layer deposition (ALD) technique. Deposition of iron phosphate thin films was achieved on nitrogen-doped carbon nanotubes (NCNTs) by combining ALD subcycles of Fe2O3 (ferrocene-ozone) and POx (trimethyl phosphate-water) at 200 -350 degrees C. The thickness of iron phosphate thin films depends linearly on the ALD cycle, indicating their self-limiting growth behavior. The growth per cycle of iron phosphate thin films was determined to be similar to 0.2, 0.4, 0.6, and 0.5 angstrom, at 200, 250, 300, and 350 degrees C, respectively. Characterization by SEM, TEM, and HRTEM techniques revealed uniform and conformal coating of amorphous iron phosphates on the surface of NCNTs. XANES analysis confirmed Fe-O-P bonding in the iron phosphates prepared by ALD. Furthermore, electrochemical measurement verified the high electrochemical activity of the amorphous iron phosphate as a cathode material in lithium-ion batteries. It is expected that the amorphous iron phosphate prepared by this facile and cost-effective ALD approach will find applications in the next generation of lithium-ion batteries and thin film batteries as either cathode materials or surface coating materials. (C) 2015 Elsevier Ltd. All rights reserved.