Preparation Of Cobalt-nickel MOFs-based Electrode Materials For Supercapacitor Performance

Transition metal cobalt-nickel-based phosphides,sulfides,and selenides are used as supercapacitor electrode materials because of their high electrical conductivity,tunable structural morphology,and low electronegativity.Their unique structures and multi-metal elements can substantially improve the electrochemical performance of the electrode materials.However,these materials also have the disadvantages of low stability and easy agglomeration.In this thesis,from the perspective of electrode material selection and material structure design,cobalt-nickel-based electrode materials with homogeneous morphology are selected,and regular and unique morphological structures are constructed by fully activating metal elements using various ways to enhance the structural stability and electrochemical performance of transition metal cobalt-nickel-based materials,as follows:（1）In this study,uniformly sized bimetallic nanoclusters Co-Ni-MOF were prepared by the solvothermal method,and subsequently Co-Ni-B-P composites were synthesized by room-temperature boronization and phosphorylation.Conditioning the Co-Ni-MOF crystal structure by using room temperature boronization and phosphorylation can fully activate the Co/Ni metal elements leading to electron transfer,thus enhancing the electrochemical performance,electrode material multiplication performance and cycle life of the electrode.The sample has an excellent performance of 1578 F·g^-1 at 1 A·g^-1.The constructed asymmetric supercapacitor device（ASC）provided a power density of 849 W·kg^-1 and an energy density of 76.5 Wh·kg^-1.This method provides an idea for synthesizing electrode materials with excellent performance.（2）The nanocubic box Fe-Co-PBA with uniform size and well-defined morphology was synthesized by room-temperature co-precipitation.Using this as a base material,the Co-Ni-MOF nanosheets were statically adsorbed on its surface.The PBA@Co-Ni-MOF was finally sulfurized to obtain PBA@CoS₂/NiS₂.The electrochemical performance of the electrode material was effectively enhanced due to the CoS₂/NiS₂ provides a large number of pores for ion shuttling,which promotes the electron transfer rate.In the electrochemical tests,the resulting samples exhibited excellent electrochemical performance of 1261 F·g^-1 at1 A·g^-1.The ASC device provided a power density of 837 W·kg^-1 and an energy density of63 Wh·kg^-1.（3）The Ni-Fe-PBA with homogeneous structure was prepared by co-precipitation method,and as a substrate material,a layer of Polydopamine（PDA）was coated on its surface,followed by the growth of Ni-Mn-LDH nanosheets on its surface.Finally,the Ni-Fe-Mn-Se composites were obtained by etching PBA@PDA@Ni-Mn-LDH using selenium acid.The sample structure was transferred to a double-layer hollow structure,and this structure can effectively mitigate the volume change of the electrode material during repeated charging and discharging.In the electrochemical test,Ni-Fe-Mn-Se has an ultra-high specific capacitance of 1435 F·g^-1 at 1 A·g^-1.