三维多级钴酸镍结构的形貌调控及其电化学性能

Morphology control and electrochemical properties of three-dimensional hierarchical NiCo_(2)O_(4) structure

形貌结构的调控对材料的电化学性能具有重要影响。本文采用溶剂热法结合煅烧在不同溶剂比及温度下合成不同形貌结构的钴酸镍,利用XRD及SEM和TEM等对样品的物相组成及形貌结构进行了表征,并对其电化学性能进行了分析。结果表明:当水与乙醇体积比为1∶1时,样品为中空的海胆状NiCo_(2)O_(4),随着水比例的增加,形貌逐渐转变为规则的中心放射状的针状形貌,且有第二相物质的存在。在水与乙醇体积比为1∶1时,随着温度的增加,形貌主要由毛绒球向花状、海胆状、中心放射状的针状过渡,而样品均为纯NiCo_(2)O_(4)。90℃合成的样品具有较好的电化学性能,在1 A·g^(−1)电流密度下,比电容高达1287.5 F·g^(−1),当扫速从20~100 mV·s^(−1)变化时,电容保持率达到59.4%,循环1500圈,比电容保持率高达80.1%,此外,在整个电化学反应过程中扩散控制过程起主导作用。

The control of the morphology and structure has an important influence on the electrochemical properties of materials.In this work,NiCo_(2)O_(4) samples with different morphologies and structures were synthesized by solvothermal method combined with calcination at different solvent ratios and temperatures.The phase composition and morphology of the samples were characterized by XRD,SEM and TEM et al,and the electrochemical performance was further studied.The results show that the sample is hollow sea urchin-like NiCo_(2)O_(4),when the volume ratio of water to ethanol is 1∶1.With the increase of the content of water,the morphology gradually changes to regular central radial needle-like morphology,and there is a second phase substance.Under the condition of the volume ratio of water to ethanol is 1∶1,with the increase of temperature,the morphology mainly changes from fluffy ball to a flower-like,sea urchin-like,and center-radiating needle,while the phases of samples are pure NiCo_(2)O_(4).The sample synthesized at 90℃exhibits better electrochemical performance.The specific capacitance is up to 1287.5 F·g^(−1) at a current density of 1 A·g^(−1).The specific capacitance retention rate reaches 59.4%with the scan rate changes from 20-100 mV·s^(−1),and the specific capacitance retention rate is up to 80.1%after 1500 cycles.In addition,the whole electrochemical reaction is dominated by the diffusion-controlled process.