Oxide Composite Material Electrodes Preparation And Research For Electrochemical Properties

In recent years, oxides as electrode materials of nano energy storage devices have been widely concerned and studied. For lithium ion battery, T1O2, for example, has been considered as a potential alternative anode materialto conventional graphite due to its excellent stable structural and safe intercalation potential. But it offers a low theoretical capacity, so it needs to be combined with material that has higher capacity. Among them, Fe2O3 owing to itsextensive sources, low price, and the high theoretical capacity, which is 1005 mAh/g, has attracted a lot of attention.However, the two oxidesall suffer from poor electrical conductivity. So we need to design a reasonable structure to solve this problem.In this study, we present a method which using Co2(OH)2CO3 as the sacrificial templates prepared by hydrothermal method, the deposited TiO2 and Fe2O3 by a stepwise ALD process, respectively, to fabricate TiO2@Fe2O3coaxial nanotube arrays composite electrode. It shows excellent electrochemical performance not only due to it combines the merits of the high specific capacity of Fe2O3 and the structural stability of TiO2 but also owing to the structure of the nanotube arrays directly grown on the Ti substrate improved its electric conductivity. Moreover, such a strategy can be readily extended to synthesize other multi-component alternative electrodes.For supercapacitor, pseudocapacitive electrode materials, Fe2O3, for example, has been considered as a promising anode material for asymmetric supercapacitors due to its proper negative potential window, rich abundance, and large theoretical capacitance. However, the poor electronic conductivity remains a great challenge that limits its development. Therefore, conductive materials are usually incorporated into Fe2O3 to make composite, which could further increase the utilization of Fe2O3. Metal sulfides usually exhibit much higher electronic conductivity than their oxide counterparts. Nevertheless, the Fe2O3@FeS2 composite has not been studied as an electrode material for supercapacitors.In this study, the Fe2O3@FeS2heterostructure with Fe2O3 nanospheres which consisting of many ultra small nanorods and anchored on FeS2 anosheets is delicately synthesized via a facile and one-pot hydrothermal method.The introduction of FeS2 greatly improved the electrical conductivity. The Fe2O3@FeS2hybrid electrode exhibited superior supercapacitive performance, demonstrating the synergistic effect of the composite electrode by hybridization of Fe2O3and FeS2. This work brings new opportunities to design Fe2O3-based composites for developing high-performance supercapacitors.