Preparation Of NiCoP Based Nanomaterials And Research On Their Electrochemical Performance

Supercapacitors（SCs）are favored candidates in energy-storage field,with high-power density,ultrafast charging and discharging.However,the wide-range application of supercapacitors in modern electronic equipment is still a challenge in terms of the low energy density.For this regard,preparing a kind of electrode material with high energy density and high cycle stability is vital important.NiCoP is a promising candidate as electrode for supercapacitors due to the ultrahigh redox activity and excellent conductivity.In this work,NiCoP nanomaterial is used as the research basis to improve its electrochemical performance from two aspects:structural engineering and doping engineering.The specific research is as follows:（1）In the first part of this work,NiCoP with intrinsic porosity structure（IP-NiCoP）was designed and prepared by adjusting the reaction conditions.The intrinsic porosity structure has many energy-storage advantages,such as:1.Providing abundant active sites for the electrochemical reaction.2.Enlarging the contact areas between the electrode and electrolyte.3.Providing a large number of electron and ion transport channels for the enhanced diffusion ability.IP-NiCoP shows excellent electrochemical performance in alkaline electrolyte.NiCoP with no intrinsic porosity structure（NP-NiCoP）was also prepared as a comparative electrode,and both the NiCo-LDH and NiCo₂O₄ participated in electrochemical tests as precursors.The specific capacitance of NiCoP electrode with intrinsic porosity structure could reach up to 1915F/g at the current density is 1 A/g,which is higher than the NiCoP without intrinsic structure（1659 F/g）、NiCo-LDH（1177 F/g）and NiCo₂O₄（1690 F/g）.In addition,the capacitance can retain 66%of its original capacitance at the current density of 10 A/g,which illustrates excellent rate performance.（2）In order to explore the conditions for improving the stability of materials,the second part of the work of this work is based on theoretical calculations,through doping engineering methods to adjust the interaction between metals and anions.Controlling the electronic structure stability essentially.The experiment is to design sulfur-doped NiCoP（S-NiCoP）nanomaterials.This part mainly includes theoretical calculations and verification of experimental results.From the theoretical simulation aspect,the band structure near Fermi level and electron delocalization structure changed after sulfur doping of NiCoP,presents an enhanced conductivity.S-NiCoP shows a larger internal space than NiCoP through simulation calculation of cell structure and atomic packing density,which can provide a relatively strong resistance to volume expansion and internal mechanical stress when the electrode material reacts with the electrolyte ion OH^-.The results of the theoretical simulation,S-NiCoP predicts an enhanced conductivity and structure stability and the electrochemical performance results verifies this.After 10,000 cycles at a current density of 5.0 A/g,the S-NiCoP electrode can maintain 85%of its original capacity,much higher than NiCoP（50%） In addition,the hybrid super capacitor battery based on S-NiCoP as cathode and AC（activated carbon）as anode can maintain 81.2% of its original capacity after 10000 cycles.