Ni-Zn Microbattery Based On Hierarchical Ordered Porous Ni/Ni（OH）₂ Microelectrode

With the rapid development of self-powered microelectronic devices,the demand for high-performance microbatteries is increasing.Nevertheless,it is difficult to get both high energy/power densities in microbatteries owing to footprint restrictions.Ultrathin microelectrode can achieve higher power density,but its lower loading of active material per unit area will lead to an unsatisfactory energy density.Increasing the thickness of microelectrodes may help to boost the loading of active material,so as to get higher areal energy density of device,but the longer electron and ion diffusion distances often result in a decreased power density.It has been proven that microbatteries based on mesostructured microelectrodes are promising to achieve high energy/power densities simultaneously.However,majority of strategies to synthesize mesostructured materials are difficult to be applied in microbatteries and the development of microbatteries based on mesostructured microelectrodes is still in the initial stage.Therefore,searching for approaches to fabricate microbatteries is an urgent mission.In this thesis,we constitute a quasi-solid-state on-chip Ni-Zn microbattries based on an interdigital hierarchical ordered porous（HOP）Ni/Ni（OH）₂ microelectrode.The morphology and composition of HOP Ni/Ni（OH）₂ microelectrode are comprehensively characterized and its electrochemical performance are also completely investigated.The main research contents and results are as follows:（1）The HOP Ni/Ni（OH）₂ microelectrode is fabricated via a colloidal templating strategy combining with anodizing and it has a porous structure composed of HOP macropores and mesopores.（2）To explore the effect of thickness of HOP Ni/Ni（OH）₂ microelectrode on the electrochemical performance,the electrochemical performances of microelectrodes with different thicknesses are measured.As the thickness of microelectrode increases,the areal energy density of HOP Ni/Ni（OH）₂ microelectrode shows an ascending trend with negligible sacrifice in power density.The negative effect of the increasing thickness on electrochemical performances is effectively reduced,which should be attributed to the optimized ion and electron transport,and increased loading of Ni（OH）₂ provided by the HOP structure.（3）As a demonstration,a quasi-solid-state Ni-Zn microbattery based on HOP Ni/Ni（OH）₂ with gel electrolyte is assembled.The fabricated Ni-Zn microbattery exhibits a considerable capacity of 150.1μAh cm^-2 at 1 mA cm^-2 and an outstanding rate performance(65.81%capacity retention at 50 mA cm^-2).In addition,it achieves ultrahigh energy/power densities(0.26 mWh cm^-2,33.8 mW cm^-2),which are considerably superior to those of most reported micro energy storage devices.