Effect Of Trace Ba²⁺ On The Magnetic And Electrochemical Properties Of Spinel Ferrites

Due to the need for green and sustainable development of modern society and various ecological issues that are constantly emerging,there is an increasing demand for research on new,low-cost,environmentally friendly and high-performance energy storage systems.Supercapacitors are considered as a very promising candidate for alternative energy storage devices due to their high rate capability,pulsed power supply,long cycle life,simple principle,high dynamic charge propagation and low maintenance cost.The electrode material is a very important factor affecting the energy storage capacity of supercapacitors,and many researchers have been working on electrode materials with simple preparation methods,excellent electrochemical properties and good stability.As a new type of electrode material,spinel-type transition metal oxide(AB₂O₄)has received more and more attention in recent years because of its superior electrochemical and conductive properties than other materials.Spinel ferrite(AFe₂O₄),as the leading one,can provide excellent performance for supercapacitor devices,especially Co Fe₂O₄ and Zn Fe₂O₄,etc.,due to their not only low cost,environmental friendliness and high natural abundance,but also multiple variable valence states,which gives them good redox performance and thus can obtain better electrochemical performance.In this paper,Co Fe₂O₄and Zn Fe₂O₄ ferrites were synthesized by sol-gel method and doped with Ba²⁺,aiming to explore the addition of trace amounts of Ba²⁺and the effects of different calcination temperatures and calcination times on their magnetic and electrochemical properties.The main contents of this article are as follows:Cobalt ferrite and zinc ferrite were first prepared by sol-gel method,and Ba²⁺was doped on this basis,and the effect of Ba²⁺addition on the synthetic sample was discussed.Then,the ratio of x=0.05 was fixed,and Ba_0.05Co/Zn_0.95Fe₂O₄ was calcined at different temperatures for 3h to explore the effect of different calcination temperatures on the performance of the samples.Finally,the ratio of x=0.05 was fixed,and Ba_0.05Co/Zn_0.95Fe₂O₄was calcined at different times at 1000°C,and the effects of different reaction times on the magnetic and electrochemical properties of the samples were explored.The results show that Ba_xCo_1-xFe₂O₄(x=0?0.09)is an anti-spinel structure with ferromagnetic properties.Ba_xZn_1-xFe₂O₄(x=0?0.09)is a spinel structure with paramagnetic characteristics.The iron ions in the sample are mostly present in the form of low spin Fe³⁺.The barium ion content increased,the lattice constant of the sample increased,the saturation magnetization intensity Ms decreased and the coercive force increased.The specific capacitance of the sample after doping is significantly greater than that of the unpoped sample,but the increase in specific capacitance and the amount of Ba²⁺addition are not proportional.With the increase of calcination temperature,the saturation magnetization intensity Ms of Ba_0.05Co_0.95Fe₂O₄ increased,and the saturation magnetization intensity Ms of Ba_0.05Zn_0.95Fe₂O₄ decreased.Changes in temperature and forging duration both affect the placement of Fe³⁺ and thus the magnetic properties of the sample.Both series of samples share a common pattern,the CV shows good reversibility of the samples,and the CP results indicate that the specific capacitance of the Ba²⁺-doped samples is significantly higher than that of the undoped samples,and the specific capacitance of all material electrodes decreases with increasing current density.