Vanadium is added to steel, titanium and aluminum to improve heat resistance and toughness. It is used as a steel additive in high-tensile steels, structural alloy steels, tool steels such as high-tensile deformed steel bars and roll which are used to construct buildings such as skyscrapers, the New National Stadium and Tokyo Skytree. It is also used as an additive for titanium alloys in aircrafts, hydrogen storing alloys and sputtering targets. In chemical applications, it is used in denitration catalysts and petrochemical catalysts. In addition, Vanadium is gathering attention as a rechargeable material for environmentally friendly redox flow batteries.