| The progress of human society in recent times cannot be so rapid without the persistent exploration and development of novel energy materials,and modern long-distance vehicles,intelligent energy storage grid and mobile communication facilities have increasingly high requirements for high-performance energy storage devices.There is a pressing need to develop clean,efficient,and long-lasting high-performance energy storage systems to meet rising energy demand,and Ni-Zn batteries（NZBs）with nickel-based materials as the positive electrode offer the benefits of high theoretical capacity,safety,environmental protection,and low cost.This paper focuses on the construction of nickel-based cathode materials for high-performance NZBs,and firstly explores effective strategies to improve the capacity of Ni-based cathode materials from the structural modulation of Ni-based hydroxides,and then tries to further optimize the rate performance and cycling stability of Ni-based materials by means of hierarchical-level nanostructure construction and material synthesis such as derived selenide and graphene composites,so the paper is mainly divided into the following parts:（1）NiCo-OH samples with different crystallinity as well as different Nito Co ratios were constructed based on a mixed solvothermal method of N-Methyl-2-pyrrolidone（NMP）and water,using NMP as a solvent while taking advantage of its modulating effect on crystallinity of hydroxide during the reaction process.Attributed to the increase of grain boundaries,ion diffusion channels and specific surface areas upon crystallization reduction,compared with the highly crystalline NiCo-OH（NiCo-OH-H）,the less crystalline NiCo OH（NiCo-OH-L）has higher specific capacity,higher rate performance and more durable cycle stability than the highly crystalline NiCo-OH-H.At the same time,due to the appropriate degree of substitution of Co element,the NiCo-OH-L based NZBs exhibits excellent electrochemical properties of both high energy and high power.（2）Based on the in situ etching-deposition-growth mechanism of Co-based metal-organic framework（Co-MOF）,NiCo-OH micro-nanosheet arrays were successfully constructed with the effect in-situ assisted derivation of Co-ZIF.The 3D hollow micro-nanosheet clustered material with a large number of ordered interstices helps the electrolyte to enter the active material rapidly and diffuse at high speed,and the active sites are effectively exposed to fully participate in the electrochemical reaction.By systematically investigating its performance as a high-rate-performance cathode for NZBs,it was found that the cathode material exhibits high reversibility,strong durability and high energy conversion efficiency for the high-speed electrochemical reaction process in NZBs,and its high specific capacity and excellent rate performance significantly exceed those of single Ni（OH）2 or Co(OH2) component and other similar NiCo-based materials.（3）By structurally compounding the hydroxide with graphene and the subsequent in situ selenization reaction,a high conductivity structure of NiCo-selenide microparticles strongly bonded with graphene substrate is constructed.In addition,the generation of NiCo bimetallic selenide is equivalent to doping NiSe2 with Co elements to enhance the electrochemical activity of NiSe2 and improve the reaction kinetics of Ni-based selenide for NZBs.This NiCo-selenide/graphene composite electrode material significantly outperforms the electrochemical performance of single-component selenides to NZBs,showing potential applications.The construction of this cathode material gives a novel concept for the development of high-performance rechargeable aqueous NZBs. |
