Mn(II)基氧化物电活化调控及其高电压水凝胶电解质微型超电容三维一体化设计

Aqueous microsupercapacitors have great advantages of low cost, high safety and high power density. Nevertheless, two key challenges still remain in obtaining high energy density and forming high-quality electrode/electrolyte interfaces. In this proposal, based on interdigitated microelectrode patterns and three-dimensional (3D) CNTs array nano-current collectors, we propose to design novel microsupercapacitors by using in-situ activated Ni1-xMnxO as the positive electrode material, MoO2 as the negative electrode material and PVA-Li, Na or K salts hydrogel as the electrolyte. In such a design, the electro-activation of Ni1-xMnxO is utilized to widen the working potential window of positive electrode, thus leading to high device voltage of ~2.4 V and high energy density of >15 μWh cm-2; and the three-dimensionally penetration and integration of electrode and hydrogel electrolyte could establish highly stable interfacial contact at the nanoscale, promoting the interfacial charge transfer. This proposal will specifically focuses on the electro-activation features, influencing factors and mechanism of Ni1-xMnxO electrode in three different kinds of electrolytes, and the key factors for the formation of stable 3D electrode/electrolyte interface as well as the unique merits of ion transport via the 3D ordered interfaces. The “structure-property” relationship between the 3D micro-electrodes, hydrogel electrolyte, the integrated interfacial architecture and the device’s performance will also be studied in detail. Our proposal provides a new concept of developing high-energy and high-safety microsupercapacitors.

水系微型超级电容器具有成本低、安全性高、功率高等优势，但如何获得高能量密度、构建高品质电极/电解质界面是两个关键挑战。本项目基于叉指微电极和CNTs阵列三维纳米集流体，提出以原位电化学活化Ni1-xMnxO为正极材料、MoO2为负极材料、PVA-锂/钠/钾盐水凝胶为电解质，设计全赝电容非对称微型超级电容器。通过电活化Ni1-xMnxO抑制水电解拓宽电位窗口来实现~2.4V器件高电压，以提高比能量（>15μWh cm-2）；利用阵列电极与水凝胶电解质的三维贯通一体化来构建纳米尺度的稳定界面，以加速电荷传递。项目拟重点研究Ni1-xMnxO在三类电解质中的电活化规律、关键影响因素及机理；研究三维电极/电解质稳定界面的形成条件，揭示三维有序界面离子输运优势；建立三维微电极、电解质及两者一体化界面结构与器件性能的构效关系，阐明性能增强机制。本项目为高能量和高安全微型超电容的设计提供了全新思路。

与有机电解液的微型超级电容器相比，水系微型超级电容器具有安全性高、成本低廉、功率密度大等优势，构建高品质电极/电解质界面、实现器件的高比能是当前该领域的研究热点，但存在极大挑战。本项目利用三维纳米集流体优势，将原位电化学活化的Ni1-xMnxO微型正极与直接沉积的MoO2等微型负极结合，设计构筑了新型全赝电容非对称微型超级电容器。通过XPS、XRD、EIS等连续监测电极材料在充放电过程中的结构演化与电化学动力学演变，系统地研究了Ni1-xMnxO正极的原位电活化规律、关键影响因素与活化机制，揭示了Ni1-xMnxO活化转变为具有更宽电位窗口的尖晶石氧化物MnNi2O4的现象，并阐明了镍离子含量与纳米碳层包覆对微型正极电化学性能的影响及其储能构效关系；制备了多类水凝胶电解质如PVA-NaClO4和PVA-LiCl等，实现了与阵列化微型正负极结构的三维一体化，构建了三维有序界面的离子输运，获得了纳米尺度界面稳定性和增强的界面电荷传输能力。项目通过协同优化碳/金属基三维集流体、水凝胶电解质与微型正负极，构建电极/电解质高品质三维界面，实现了微型超电容2.4 V及以上的高电压，并充分利用了全赝电容正负极的高比容量特性，促使器件最高比能量达到126.67 μWh cm-2，循环稳定性大于5000圈，综合性能优于已报道的诸多微型电化学储能体系。本项目的实施为高电压、高比能和高安全微型超电容的设计提供了有益参考，对发展其他高性能水凝胶电解质微型电化学储能器件亦具有十分重要的科学意义。