掺杂钴酸镍/有序介孔碳复合材料的结构控制、相互作用及超级电容性能研究

Spinel nickel cobaltite (NiCo2O4) has attracted more and more attentions for its high performance as supercapacitor material. But its reversibility of charge-recharge and electrical conductivity at high current density need to be increased for actual application. In this project, doping with some transition cations, such as Mn, Fe, Zn, is considered as an effective strategy to expand the working potential range of NiMxCo2-xO4. And the effects of amount of doped metals and temperature of heat treatment on the crystal particle size, morphology and pore structure of NiMxCo2-xO4 are investigated in detail. Polyimide prepolymer with plenty of carboxyl and imine groups, which can capture metal ion by electrostatic interaction or through ion exchange, can be processed and carbonized to the composites of NiMxCo2-xO4/ordered mesophore carbon using SBA-15 as hard template. The synergic energy storage mechanism in the composite including pseudocapcitance and double-layer capacitance models should be constructed and analyzed. The electrical conductivity of the composite can be enhanced and the pore structure and surface contents of the ordered mesoporous carbon may be changed since the heat treatment process produce more graphitic structure with doped metals. The asymmetrical capacitors are assembled with NiMxCo2-xO4/ordered mesophore carbon cathode and activated carbon anode, and their cycling stability and rate performance are studied. The composite materials can expand the range of actual device as it has both redox reaction mechanism and double electric layer charge stores. The research of this project is beneficial to the understanding of the interfacial electron transfer among nano-oxide particles and the ion deliver between electrode and electrolytes.

NiCo2O4材料是近年来高性能超级电容器极具发展前景的材料之一，但仍然存在电子导电性较低，大电流下充放电可逆性不高的缺陷。项目利用多种金属元素（Mn,Zn,Fe）对NiCo2O4掺杂，扩展其电化学可逆反应电位范围，探讨元素掺杂影响NiMxCo2-xO4的晶粒尺寸、纳米形貌及孔结构变化的规律。利用富含羧基的聚酰亚胺（PI）预聚体链段与金属盐的静电作用或离子交换原位锚定金属离子，阐明NiMxCo2-xO4的赝电容及介孔碳的双电层电容协同储能机理。采用模板法控制有序介孔碳的孔道结构；探究金属离子/聚酰亚胺前驱体的热处理过程中碳石墨结构、孔结构及表面组成的变化规律。组装NiMxCo2-xO4/有序介孔碳//活性炭不对称电容器，研究其循环稳定性和倍率性能。项目的研究有利于丰富纳米氧化物/多孔碳电极材料界面电子传递、离子传递规律的认识，扩展超级电容器应用领域。

高性能的超级电容器在电动车、太阳能、风能、等新能源及可穿戴设备等新型电子器件中具有广阔的应用前景。项目基于纳米技术手段，构建了一系列具有纳米结构的镍钴金属氧化物、硫化物，以及其与碳材料、导电聚合物等构成的复合物，研究了这些纳米材料结构、电化学性能及储能机理。项目成功合成了氮掺杂有序介孔碳材料，发现氮含量对其比容量具有重要影响，该材料比表面积达890 m2/g，孔径集中在3.6nm，氮含量高达7.94wt.%。在碳布上原位生长了多孔NiCo2O4纳米阵列材料及包覆聚吡咯复合材料，研究发现高电导率的PPy纳米包覆层，提高了复合材料的电子导电性，而均匀分布在碳布上NiCo2O4纳米花，增大了其与电解液接触面积，从而赋予该材料优异的电化学性能。首次在氯化胆碱-尿素低共熔溶剂体系中，通过共沉淀法合成纳米中空NixCo2-x(OH)3Cl材料，避免水热法必须的高压高温条件。该材料在LiCl+LiOH混合电解液中具有高的循环稳定性，其机理是Cl-阻止了Cl-/OH-的交换，从而稳定了NixCo2-x(OH)3Cl的晶体结构。成功合成了N、S共掺杂多孔碳/碳纳米管负载CoS2纳米粒子，该材料具有规整的十二面体形貌，且原位生成的碳纳米管赋予复合材料良好的导电性。研究了多种硫化物异质结的合成方法，得到了Ni3S4/Co3S4/MoS2异质结、Co3S4@Ni3S4及Co3S4/CoSe2材料，其中具有核壳结构的Co3S4@Ni3S4纳米花具有2817F/g的高比电容（1A/g）。组装了Co3S4@Ni3S4//AC柔性不对称超级电容器，当功率密度为799.7 W/kg时，其能量密度达54.2 Wh/kg，优于一些文献报道的硫化物或氧化物组装而成的超级电容器性能。项目的研究结果对于高性能纳米材料的合成及不对称电容器的发展具有良好的推动作用。