柔性储能器件的机械性能、能量密度、充放电速度等特性极大地影响着可穿戴设备和柔性电子领域的发展。混合电容器作为锂离子电池与超级电容器的结合，具有良好的应用前景。本论文针对柔性混合电容器正负极材料在比容量、动力学方面不匹配的问题，分别对正负极材料进行研究，在保持电极材料良好柔性的基础上提高其电化学性能。 首先通过简单的溶液法合成了纳米级的金属有机骨架（MOF）材料Zn-MOF和Cu-MOF，通过安全、高效率、低成本的气纺丝工艺将Cu-MOF和Zn-MOF分别引入到聚丙烯腈（PAN）纤维。通过碳化以及硫化，制备得到了铜硫化物/碳纤维复合负极材料，引入Cu-MOF改善了负极材料的孔隙结构，且活性物质均匀分布在碳纤维上，进而表现出极高的倍率性能（40 A g-1时比容量为170 mAh g-1），对引入Zn-MOF的PAN纤维进行高温碳化以及氨气活化得到多孔碳纤维正极材料，比表面积为1522 m2 g-1，并表现出层次化的孔结构。将正负极材料组装得到锂离子混合电容器，具有106 Wh kg-1的能量密度和90 kW kg-1的功率密度，组装为软包电池后在弯折条件下具有良好的电化学稳定性。 其次，为了进一步提高混合电容器的能量密度与循环稳定性，通过气纺丝工艺在碳纤维前驱体中引入了Zn和Cu双金属源，通过碳化以及硫化工艺得到了ZnS/CuS双金属硫化物与碳纤维的复合负极，利用两种金属硫化物之间的协同效应，纳米级的活性物质颗粒均匀分散在纤维上，得到的负极材料具有极高的比容量（0.2 A g-1的电流密度下超过900 mAh g-1）以及优异的倍率性能（20 A g-1的大电流密度下比容量为300 mAh g-1）。将其与水蒸气活化后的多孔碳纤维正极材料组装为锂离子电容器，显示出最高136 Wh kg-1的能量密度，循环次数达到4000圈。组装为软包电池以后在弯折条件下可稳定循环1000圈。 本文针对目前柔性混合电容器负极材料倍率性能、循环性能差的问题，在碳纤维中引入了高容量的过渡金属硫化物（TMSs），利用碳纤维的三维网状结构均匀分散活性物质，充分发挥了过渡金属硫化物材料的高容量、高倍率特性。这为后续构建高倍率性能的柔性混合电容器提供了思路。
The mechanical property, energy density and rate performance of energy storage devices greatly influence the development of flexible electronics. As a combination of lithium ion batteries and supercapacitors, hybrid capacitors have good application prospects. In this thesis, to address the mismatch in specific capacity and kinetics between anode and cathode materials, we explored two electrodes separately to improve their electrochemical performance while maintaining good flexibility of the materials. Firstly, the nanoscale Metal-Organic Framework (MOF) materials, Zn-MOF and Cu-MOF, were synthesized by a simple solution method. Cu-MOF and Zn-MOF were introduced into polyacrylonitrile (PAN) fibers by a safe, high-efficiency and low-cost blow-spinning method. Copper sulfides/carbon fiber (CF) anode material was prepared by carbonization and subsequent sulfidation process, the introduction of Cu-MOF adjusted the pore structure of anode material, and the active particles were uniformly distributed on the carbon fibers. As a result, copper sulfides/carbon fiber anode exhibits a superior rate performance (170 mAh g-1 at 40 A g-1). Through high-temperature carbonization and NH3 activation of PAN fibers with Zn-MOF embedded, the obtained porous carbon fiber cathode presents a high specific surface area of 1522 m2 g-1 and hierarchical porous structure. The anode and cathode were assembled as Li-ion capacitor, which presents an energy density of 106 Wh kg-1 and a high-power density of 90 kW kg-1. After being fabricated as pouch cell, it exhibits good cycle stability under bending conditions. Secondly, in order to further improve the energy density and cycling stability of hybrid capacitor, Zn and Cu bimetallic sources were introduced into carbon fiber precursor through the same blow-spinning process. The anode material of ZnS/CuS-CF composite was obtained through the carbonization and sulfidation process. Benefitting from the synergistic effect of the two kinds of metal sulfides, the active nanoparticles were uniformly dispersed on the carbon fibers. The obtained anode material performs a superior specific capacity (over 900 mAh g-1 at 0.2 A g-1) and outstanding rate performance (300 mAh g-1 at 20 A g-1). After being coupled with porous carbon fiber cathode material which was activated by H2O steam, the obtained Li-ion capacitor shows an improved energy density up to 136 Wh kg-1 with a long cycle life about 4,000 cycles. When being assembled as a pouch cell, it exhibits good electrochemical stability after 1,000 cycles. In this thesis, to address the problems of poor rate performance and cycling stability of anode materials for flexible hybrid capacitors, transition metal sulfides (TMSs) with a high specific capacity were introduced into carbon fibers, the active particles were uniformly dispersed benefitting from the three-dimensional mesh structure of carbon matrix, which helps to make full use of the high-capacity and high-rate characteristics of TMSs. This thesis provides possible direction for the construction of high-power density flexible hybrid capacitors.
