稀土掺杂氢氧化镍1D纳米线可控制备并与石墨烯导电网络组装及其电化学性质研究

Graphene conductive networks possess open architecture and excellent electron, ion transmission performance. Nickel hydroxide one-dimensional nanowire structures provide greater stability for high capacity and stability electrode materials. The goal of this project is to explore high-current chargeable and dischargeable electrode materials. Nano-graphene networks and one-dimensional nanowire cross-linked networks structures will be constructed with the introduction of heavy rare earth elements in the structure and assembled into three-dimensional ordered composite electrode materials, which resolve the conflict of large current charge -discharge between small discharge specific capacity and cyclic performance, and then improve high temperature performance. Graphene conductive networks can be built by CVD. heavy rare earth elements doped nickel hydroxide one-dimensional nanowire will be controllable prepared through the hydrothermal method. Then the one-dimensional nanowire cross-linked networks structure and nano graphene network can assembly together by interaction-driven force. Also the construction and assembly can be finished in one step by in situ synthesis. The performances of resulting composite as electrode materials in nickel-metal hydride batteries will be studied in the high-current charge-discharge process. The relationship between structural characteristics of the composite electrode materials and high-current charge-discharge performance will be illustrated. This project will promote the development of electrode materials for new high-current chargeable and dischargeable battery, which would lay the basis for nano material directly used as electrode materials for nickel-metal hydride batteries.

石墨烯导电网络具有开放结构和良好电子、离子传输性能。氢氧化镍一维纳米线作为电极材料提供高容量和高稳定性。本项目以可大电流充放电电极材料为目标，构建纳米石墨烯网络和一维纳米线交联网络结构并在其结构中引入重稀土元素，组装成为三维有序复合电极材料，解决大电流充放电和放电比容量低及循环性能差的矛盾，从而改善其高温性能。通过化学气相沉积法构建石墨烯导电网络，水热法可控制备重稀土元素掺杂氢氧化镍一维纳米线。利用弱相互作用驱动自组装，将纳米线交联网络结构组装到纳米石墨烯网络，形成复合电极材料。通过原位合成，实现结构构建和组装一步进行。将所得复合材料作为镍基电池正极材料，研究其在大电流充放电条件下的性能和行为。探究复合电极材料结构特征及变化与大电流充放电性能的关系。本项目有助于研究大电流充放电条件下电极材料的结构特征和变化规律，促进新型大电流充放电电池材料开发，为纳米材料直接用于镍氢电池电极材料奠定基础。

本项目主要是围绕过渡金属氧化物/氢氧化物电极材料的设计和调控进行研究，采取了金属掺杂、石墨烯复合和界面调控等手段，解决了过渡金属反应动力学缓慢、表面活性位不足以及结构稳定性差的问题。采用Y作为掺杂剂，Y-Ni(OH)2电极不仅具有优异的比电容，而且获得了良好的循环寿命，其容量保持率为72.39%(6000次)。Y的引进加速了电极体系内部的反应动力学，同时提高了电荷转移效率。在此基础上，进一步引进石墨烯来改善整个电极表面的湿润性，促使电解质离子的渗透。Y-Ni/GNS异质结构在1 A/g下获得822.3 C/g的比容量，经过6000次循环后其比容量保持率达到了76.24%。. 基于3D网状结构是由一种纳米薄膜和纳米线构成的网状材料,以泡沫镍作为生长基底，合成了一种网络状Co3O4/NiCo-LDH复合电极材料。该材料在电流密度为1 A/g时，获得的最优放电比容量为1067 C/g。组装的Co3O4/NiCo-LDH//AC器件获得了74.4 Wh/kg的能量密度，其对应的功率密度为989 W/kg，经过7000次循环后，该器件的比电容仅损失了8.43%。. 基于核壳结构是一种由纳米片/纳米线和纳米片组成的高性能储能材料，构建了一种NiCo2S4纳米片包覆NiCo-LDH纳米片的核分支结构。高活性的NiCo2S4材料可通过高效的氧化还原反应为整个体系提供大量的电荷，弥补了内层NiCo-LDH的不足。由于内外层活性物质之间具有强的协同电化学作用，核壳型NiCo2S4@NiCo-LDH电极表现出优异的储能特性，在1 A/g下达到1385.7 C/g的比容量。组装的NiCo2S4@NiCo-LDH//AC元件具有93.21 Wh/kg的能量密度，展现出优异的存储能力。