面对化石燃料短缺和能源需求量增加的问题，高效和可持续地利用能源成为了人们的目标，而实现这一目标离不开综合性能良好的储能设备的开发。近年来，超级电容器因具有充放电速率快、功率密度高、循环寿命长等优点引起了广泛的关注，而其性能主要取决于组成电极的特性。大量研究表明，合理设计多组分电极材料是提高电极性能的有效途径。受益于各组分间的相互作用，多组分电极材料不仅能提供更多的储能活性位点，而且还能改善电极材料的反应动力学及机械稳定性。此外，在众多电极材料中，钴基电极材料因其理论容量高、价态变化丰富、晶体稳定性好备受关注。然而，目前报道的一些钴基电极材料仍存在比容量低、循环稳定性差、内阻高等问题，钴基电极材料的性能远没有达到理论水平，其性能仍有很大的提升空间，因此对钴基电极材料进行深入研究很有必要。基于以上分析设计了两种多组分的钴基电极材料，主要内容如下：

通过简单的两步水热反应，合成了NiCo(CO₃)(OH)₂-Co(CO₃)_0.5(OH)（NCCH-CCH）纳米线电极材料。在具有较高倍率性能的NiCo(CO₃)(OH)₂和高稳定性的Co(CO₃)_0.5(OH)的协同作用下，NCCH-CCH电极材料展现出了较为优异的电化学性能。该电极在1 A g^-1下表现出937 C g^-1的高比容量，并且在循环15000圈后，仍具有80.9%的容量保留率。以NCCH-CCH电极作为正极，酸刻蚀的碳布作为负极，组装的混合超级电容器提供了1.6 V的宽电位窗口、156.7 μWh cm^-2 的高能量密度（0.8 mW cm^-2）、8.0 mW cm^-2的高功率密度（74.2 μWh cm^-2）以及出色的循环稳定性（17.5 mA cm^-2下循环15000次电容保留率为88.9%）。

在相对较低的水热温度（90 ℃）下，经一步水热反应制备了纳米片包裹纳米粒结构的NiCo₂O₄@Mn(OH)₂（Co-Mn-O-H）电极材料。得益于具有高比容量的NiCo₂O₄和较快的电荷转移动力学的Mn(OH)₂的协同作用，Co-Mn-O-H具有较好的导电性和氧化还原活性，表现出较优异的电化学性能。该电极在1 A g^-1时的比容量为1219.0 C g^-1，30 A g^-1电流密度下循环5000圈的容量保留率为93.8%。以Co-Mn-O-H电极作为正极，酸刻蚀的碳布作为负极，组装的不对称超级电容器可提供56.8 μWh cm^-2 的较高能量密度（0.7 mW cm^-2）和3.5 mW cm^-2的较高功率密度（32.1 μWh cm^-2），并且具有较好的循环稳定性（10 mA cm^-2下循环5000次后电容保留率为87.0%）。

Facing the shortage of fossil fuels and the increasing demand for energy，the efficient and sustainable use of energy has become the goal of people, and the development of energy storage devices with good comprehensive performance is indispensable to achieve this goal. In recent years, supercapacitors have attracted widespread attention due to their fast charge and discharge rates, high power density and long cycle life, and their performance mainly depends on the characteristics of the constituent electrodes. Numerous studies have shown that the rational design of multi-component electrode materials is an effective way to improve the performance of electrodes. Benefiting from the interaction between the components, multi-component electrode materials not only provide more active sites for energy storage, but also improve the reaction kinetics and mechanical stability of the electrode materials. In addition, among many electrode materials, cobalt-based electrode materials have attracted much attention because of their high theoretical capacity, rich valence changes and good crystal stability. However, some of the cobalt-based electrode materials reported so far still have problems such as low specific capacity, poor cycling stability and high internal resistance. The performance of cobalt-based electrode materials is far from the theoretical level and there is still much room for their performance to be improved, so it is necessary to conduct in-depth research on cobalt-based electrode materials. Based on the above analysis, two multi-component cobalt-based electrode materials are designed, the main contents are as follows:

NiCo(CO₃)(OH)₂-Co(CO₃)_0.5(OH) (NCCH-CCH) nanowire electrode materials were synthesized by a simple two-step hydrothermal reaction. Under the synergistic effect of NiCo(CO₃)(OH)₂ with high rate performance and Co(CO₃)_0.5(OH) with high stability, NCCH-CCH exhibits excellent electrochemical properties. The as-prepared NCCH-CCH electrode displays a high specific capacity of 937 C g^-1 at 1 A g^-1 with ultralong lifespan (80.9% after 15000 cycles at 20 A g^-1). A hybrid supercapacitor is assembled applying the NCCH-CCH as positive electrode and acid etched carbon cloth as negative electrode, which provides a wide potential window of 1.6 V, high energy density (156.7 μWh cm^-2 at 0.8 mW cm^-2), high power density (74.2 μWh cm^-2 at 8.0 mW cm^-2), and excellent cycling stability (88.9% capacitance retention after 15000 cycles at 17.5 mA cm^-2).

NiCo₂O₄@Mn(OH)₂ (Co-Mn-O-H) electrode materials with nanosheet-encapsulated particle structure grown on nickel foam were prepared by a one-step hydrothermal reaction at a relatively low hydrothermal temperature (90 °C). Thanks to the synergistic effect of NiCo₂O₄ with high specific capacity and Mn(OH)₂ with fast charge transfer kinetics, Co-Mn-O-H has good electrical conductivity and redox activity and exhibits excellent electrochemical performance. The electrode has a specific capacity of 1219.0 C g^-1 at 1 A g^-1, and a capacity retention rate of 93.8% after 5000 cycles at 30 A g^-1. The asymmetric supercapacitor assembled with the Co-Mn-O-H electrode as positive electrode and acid etched carbon cloth as negative electrode provides high energy density (56.8 μWh cm^-2 at 0.7 mW cm^-2), high power density (32.1 μWh cm^-2 at 3.5 mW cm^-2), and good cycling stability (87.0% retention of capacitance after 5000 cycles at 10 mA cm^-2).