Controllable Fabrication Of Transition Metal Sulfur/Selenium Compounds And Their Application In Electrochemical Energy Storage

In order to establish a green,low-carbon and recyclable economic development mode,the construction of new energy storage system,especially electrochemical energy storage devices,has become one of the effective approaches to control energy consumption and carbon dioxide emission.With the development of science and technology,great progress has been made in the field of electrochemical energy storage devices,especially supercapacitors and alkali metal ion batteries.In this thesis,we select Binary-metal disulfides and diselenides as active materials to study their performance as supercapacitor and sodium ion battery,respectively.The detailed contents are as follows:（1）The Co_0.5Ni_0.5S₂-C double-shell porous microspheres(Co_0.5Ni_0.5S₂-C DSPMs)are fabricated via sulfuration treatment in N₂ atmosphere using CoNi-MOF as template.With the aid of Co_0.5Ni_0.5S₂-C and the unique structure of double-shell porous microspheres,the Co_0.5Ni_0.5S₂-C DSPMs as electrode material presents an outstanding specific capacity of 2011.3F·g^-1 at the current density of 1 A·g^-1.The asymmetric supercapacitor（ASC）assembled with Co_0.5Ni_0.5S₂-C DSPMs as cathode and activated carbon（AC）as anode can not only provides high specific capacity(182.4 F·g^-1 at 1 A·g^-1)and energy density of 64.85 Wh·kg^-1 at the power density of 800 W·kg^-1,but also shows an excellent cycle stability with 92.78%capacitance retention rate at the current density of 8 A·g^-1over 5000 cycles.（2）CoNi-MOF hollow microspheres are synthesized by microwave hydrothermal method.After sulfuration treatment,the NiS₂/Co_0.5Ni_0.5Se₂-C hollow porous microsphere(named NiS₂/Co_0.5Ni_0.5Se₂-C HPMS)are obtained.After a detailed study of the formation mechanism of NiS₂/Co_0.5Ni_0.5Se₂-C HPMS,we find that this strategy is suitable for the synthesis of other bimetallic selenide hollow porous microspheres such as Fe_0.4Ni_0.6Se₂-C HPMS as well.Due to the special porous hollow structure,the NiS₂/Co_0.5Ni_0.5Se₂-C HPMS as the negative electrode material of sodium ion battery（SIBs）not only has good chemical reaction kinetics and excellent sodium storage performance,but also provides a large space for the volume change of Na⁺extraction/insertion process.The specific capacitance of sodium ion battery that is assembled by using NiS₂/Co_0.5Ni_0.5Se₂-C HPMS as negative and sodium metal as positive electrode still remains 562.9 m Ah·g^-1 at the current density of 0.1 A·g^-1.These results demonstrate that the NiS₂/Co_0.5Ni_0.5Se₂-C HPMS exhibits excellent performance in sodium storage.