Fabrication And Electrochemical Investigation Of MMoO₄?M=Ni?Co?nanomaterials As High-performance Anode Materials For Sodium-ion Hybrid Capacitors

Nowadays,with the increasing demands of mobile devices,the clean energy plays an increasingly important role in modern society to satisfy the need of green development.At the same time,due to the two problems about the clean energy that are intermittent and unstable asked the next generation of energy storage technology has a breakthrough development.As the main energy storage device,the batteries and super capacitors had been the hot research,because the advantage of their convenience and stability.We all know,with the government's promotion and subsidies for lithium batteries,the lithium battery industry has ushered in a development opportunity.But compared the batteries and super capacitors,there are an imagine that we can design an energy storage device which combine the advantages of double layer capacitors and batteries,fortunately there are some work about this imagine,these new devices had been called lithium-ion hybrid capacitors.In addition,considered the widely applications of lithium battery will affect reserves of the lithium,this asked us to look for other rich elements to replace the lithium.The elements of lithium and sodium were in the same main group.So,it is obvious that sodium-ion is a best element can replace the lithium which has a rich resource and is cheaper.And there are few works in the area of the Sodium-ion hybrid capacitors.So,as the new generation of potential and environmental friendly energy storage devices,the NHCs will become the new energy devices,which will be widely applied in the future,especially in the field of emerging energy applications.But,as the past report,the radius of the sodium ions is larger than lithium ions?Na⁺:1.06?,Li⁺:0.76??,which makes it impossible that use the same electrode materials in these different system.Therefore,the most important thing is to find suitable electrode materials which can store the Na ion effectively.According to the study,the NiMoO₄ has been used as the electrode materials of super capacitors and has a specific capacity.CoMoO₄ has been used as the electrode materials of super capacitors and lithium batteries,because it has a specific capacity.So we decided to adopt appropriate methods to synthesis of these samples and explore their electrochemical properties as anode materials for sodium-ion hybrid capacitors.The NiMoO₄/Ni composites and the CoMoO₄ are successfully synthesized by one-step hydrothermal route.In this work,the NiMoO₄/Ni composites and he CoMoO₄ are used as anodes and which will assembled with cathode material?AC?to form the sodium-ion hybrid capacitors.The NiMoO₄/Ni//AC system has a high energy density of 62.4 Wh kg^-11 and a high power density of 3500 W kg^-1.It also exhibits prominent cycling stability that the capacity retention is about 70%after 6000 cycles.From this work the nanostructure of the CoMoO₄had an excellent sodium ion storage property,the half-cell of CoMoO₄ electrode achieve a high specific capacitance of 300 mA h g^-11 after 100 cycles with the current density of 50 m A g^-1.With an expanded potential that range from 0 to 3.5 V,the specific capacitance and the high energy density of CoMoO₄//AC is 37.2 F g^-11 and 63.3 Wh kg^-11 at a current density of0.05 A g^-1,respectively.It can be retained nearly 90%until 6000 cycles at a current density of0.5 A g^-1.Therefore,sodium-ion hybrid capacitors?NHCs?which the Ni MoO₄ and CoMoO₄were used as the electrode materials are considered to be the new-generation environment-friendly energy storage devices,and they are expected to be widely used in future,especially for emerging energy applications.