【作者】 彭莉；

【导师】 肖鹏；

【作者基本信息】 重庆大学 ， 物理学， 2020， 硕士

【摘要】 超级电容器作为超大功率的电化学储能器件已被广泛用于各个领域,例如混合动力汽车、便携式电动工具等。但其相对较低的能量密度仍旧是阻碍超级电容器进一步发展的重要因素。电压窗口作为直接影响超级电容器能量密度的因素而受到研究者们的广泛关注。目前,电压窗口的拓宽主要从电解质溶液,电极材料和两电极匹配三方面进行,其中两电极匹配,尤其是针对赝电容材料之间的电极匹配研究较少。本论文通过为正极材料匹配不同赝电容负极材料,探究两电极匹配对非对称超级电容器的电压窗口、比电容、能量密度与功率密度等方面参数的影响。此外,从电极材料功函数角度对非对称超级电容器电压窗口的拓宽机理方面进行了研究。具体研究内容如下:首先通过简易的原位氧化还原的方法制备了高性能纳米碳@K_0.5Mn₂O₄正极材料,并选取四种金属氧化物Mo O₃、Fe₂O₃、V₂O₅、WO₃作为负极材料。单电极研究发现,在1 A g^-1电流密度下,正极材料在1 M Na₂SO₄电解质溶液中具有约300 F g^-1的高比电容和高达1.2 V的稳定电压窗口。四种不同负极材料在电压窗口方面差别不大,其中Mo O₃与V₂O₅电压窗口略低于Fe₂O₃和WO₃。其次,将纳米碳@K_0.5Mn₂O₄正极材料与所选的负极材料分别组装成四组非对称超级电容器器件并对其储能性能进行了研究。研究发现在1 M Na₂SO₄电解质溶液中,以Mo O₃为负极的非对称超级电容器性能最优。其在5.95 k W kg^-1的功率密度下能量密度为66.7 Wh kg^-1,并表现出2.42 V稳定电压窗口。而以V₂O₅、Fe₂O₃、WO₃为负极的非对称超级电容器电压窗口分别为2.4 V、2.3 V、2.2 V。利用开尔文探针力显微镜,从两电极材料之间的功函数角度对产生上述电压窗口差异的原因进行了研究。研究发现,对于赝电容电极材料,两电极的功函数差异越大,所得器件的稳窗口越大,而拓宽电压窗口使得非对称超级电容器器件的能量密度得到显著提升。更多还原

【Abstract】 Supercapacitors can provide ultra-high power and is widely used in various fields.Although it can meet the power requirements of hybrid vehicles,portable power tools,etc.as a green and environmentally friendly energy storage device,its relatively low energy density is still an important factor hindering its further development.Specific capacitance and potential window are important parameters for supercapacitors that directly affect the energy density and have received extensive attention,in recent years.In order to widening the voltage window,three aspects need to be focused:electrolyte solution,electrode materials and the matching of electrode materials.Among them,the research on the matching of electrode materials,especially for pesudocapacitor materials,is less studied.This paper intends to match the different pseudocapacitor negative electrodes with the prepared positive electrode material and explore the matching effect in voltage window.In addition,related research was conducted on the effect of work function difference on the potential window of the supercapacitor during the matching process.Following work were carried out for the above research purposes,in this thesis:Firstly,a high-performance nano-carbon@K_0.5Mn₂O₄ positive electrode was prepared by a simple in-situ redox method,Mo O₃,Fe₂O₃,V₂O₅,and WO₃ were selected as the matching negative electrode materials.The electrochemical test showed that the specific capacitance of positive electrode was about 300 F g^-1in a 1 M Na₂SO₄electrolyte solution(1 A g^-1).Meanwhile,the positive electrode also demonstrated a stable voltage window of up to 1.2 V.The four metal oxide anodes showed an approximate single-electrode potential window,about-0.2-0.9 V.Secondly,we assembled four asymmetric supercapacitor device by the nano-carbon@K_0.5Mn₂O₄ as positive electrode and four metal oxide as negative electrode respectively and investigated the energy storage performance.In the 1 M Na₂SO₄ electrolyte solution,carbon@K_0.5Mn₂O₄//Mo O3 presented the best performance,it’s power density achieved 66.7 Wh kg^-1 when the power density was5.95 k W kg^-1,and it showed the highest voltage window of 2.42 V.Finally,the influence of the work function difference between the two electrode materials on the potential window of the asymmetric supercapacitor during the matching process was also studied.We used the Kelvin probe force microscope to measure the work function difference between two materials.The study found that the greater the difference of the work function of the two pseudocapacitive electrodes,the larger the voltage window of the resulting device.更多还原