|Preparation of nickel cobalt layered double hydroxide and its application in micro energy storage devices
|Place of Conferral
|镍钴层状双氢氧化物 NiCo layered double hydroxide 氧化铟锡纳米线 indium tin oxide nanowires 盐包水电解液 water-in-salt electrolyte 平面微型储能器件 planar micro energy storage devices
（1）通过界面调控利用氧化铟锡纳米线（ITO NWs）和聚吡咯（PPy）改善NiCo-LDH的导电性和微观结构稳定性，制备高性能的面内叉指非对称微型超级电容器。首先，以化学气相沉积法（CVD）制备的三维ITO NWs导电网络为活性材料的集流体，导电网络极大的增加了活性物质的负载量并加速了电荷的快速转移。通过电沉积在ITO NWs上成功生长NiCo-LDH纳米片，为了防止NiCo-LDH纳米片的团聚和脱落，保持微观结构稳定，通过电聚合在前面得到的复合电极上包覆一层PPy。PPy的包覆提供了除ITO NWs之外的额外电子传输路径，而且作为外壳也可以防止NiCo-LDH结构在电荷储存过程中大幅度的膨胀和收缩，从而提升NiCo-LDH的循环稳定性。选用“盐包水”（9.2 M NaClO4·H2O）电解液拓展电化学稳定窗口，PPy@NiCo-LDH@ITO NWs单电极表现出0~1.3 V较宽的电压工作范围，在扫速为5 mV s-1时面电容为598 mF cm-2；并且在10000次充放电循环后电容保持率为83%，展示了优异的长循环稳定性。得益于生长在ITO NWs上PPy包覆的NiCo-LDH分层结构以及宽电压窗口的WIS电解液，组装的正极PPy@NiCo-LDH@ITO NWs//负极PPy@FeOOH@ITO NWs非对称微型超级电容器（MSCs）具有0~2.5 V的工作电压范围，最大面电容为63.04 mF cm-2，并且在功率密度为294.1 mW cm-3时提供了32.2 mWh cm-3的高体积能量密度。另外，通过串并联照明测试进一步证明了器件良好的一致性。
（2）激光刻蚀技术辅助合成无隔膜的水系高安全性Zn//NiCo-LDH@ITO NWs@CC平面微型锌电池。基于可手工操作的炭布（CC）和锌箔（Zn），通过界面调控利用生长在CC上的ITO NWs（ITO NWs@CC）作为集流体来改善NiCo-LDH的导电性和循环过程中微观结构的稳定性。之后，通过激光刻蚀将ITO NWs@CC和Zn分别刻蚀为两个独立且相同尺寸的叉指。在ITO NWs@CC叉指上电沉积NiCo-LDH得到正极NiCo-LDH@ITO NWs@CC，以Zn为负极，在AB胶、导电凝胶和CC导线的辅助下，在载玻片上组装成Zn//NiCo-LDH@ITO NWs@CC微型锌电池（ZMB）。三维ITO NWs@CC导电网络可以增加活性物质的负载量、促进电荷的快速转移并缓冲长循环过程中活性材料的大幅度膨胀和收缩，从而提升ZMB的性能和寿命。水系ZMBs在1 mA cm-2时提供了0.56 mAh cm-2（453.5 mAh g-1）的面容量，获得最大的能量密度为798.4 μWh cm-2（649.9 Wh kg-1）和功率密度4.1 mW cm-2（3.29 W kg-1），表现出较好的倍率性能（电流密度从1 mA cm-2增至3 mA cm-2容量保持率为63.8%）和出色的循环稳定性（在1 mA cm-2下循环1000次后容量保持率为101%）。此外，ZMBs的串并联和点灯测试证明了器件的一致性。因此，合成快速、简单的平面叉指型ZMB为下一代高性能、绿色友好和可扩展的平面微型储能器件提供了参考。
The rapid development of miniaturized, wearable electronics has led to higher requirements for planar miniaturized electrochemical energy storage systems with high performance, high safety, long life, and integrability. For example, in terms of the shape, size, mechanical properties, stimulus response capability, and environmental adaptability of the device, it is required to achieve design, self-healing, integration, and miniaturization. Compared with traditional energy storage devices with a diaphragm sandwich structure, the planar interdigitated structure has significant advantages such as short ion transmission distance, long cycle life and excellent power density. As a micro-unit that can be integrated in a large number of planes, it has become the main energy supply object for microelectronic devices. In addition, the planar interdigitated energy storage device has a convenient and space-saving connection method as well as a flexible shape and size design, which can greatly improve the output voltage and the energy density of the energy storage device.
High conductivity and a large number of charge storage reaction sites are key features of high-performance energy storage materials. Layered double hydroxides (LDHs), commonly known as hydrotalcites, are layered structures composed of multiple positively charged metal layers and anions that balance charges in the middle. Among them, nickel-cobalt layered double hydroxide (NiCo-LDH) is widely used as an energy storage material due to its strong electrochemical activity, high theoretical specific capacity, adjustable layered structure, and simple synthesis process. However, the poor conductivity of the material itself and the microstructure that is difficult to maintain during the long-term cycle make the charge storage capacity of energy storage devices still have a lot of room for improvement. Based on this, this thesis improves the conductivity and structural stability of NiCo-LDH through interface regulation, and prepares an in-plane interdigitated, integrable micro energy storage device. The following are the main research findings:
(1) Using ITO NWs and polypyrrole (PPy) to improve the conductivity and microstructural stability of NiCo-LDH through interfacial modulation, a high-performance in-plane interdigitated asymmetric micro-supercapacitor was prepared. First, the three-dimensional ITO NWs conductive network was prepared by chemical vapor deposition (CVD) as the current collector of the active material. The conductive network greatly increased the loading of the active material and accelerated the rapid charge transfer. NiCo-LDH nanosheets were successfully grown on ITO NWs by electrodeposition. In order to prevent the agglomeration and shedding of NiCo-LDH nanosheets and keep the microstructure stable, a layer of PPy was coated on the composite electrode obtained above by electropolymerization. The coating of PPy provides an additional electron transport path in addition to ITO NWs, and as an outer shell, it can also prevent the large expansion and contraction of the NiCo-LDH structure during the charge storage process, thereby improving the cycle stability of NiCo-LDH. The "water-in-salt" (9.2 M NaClO4·H2O) electrolyte was selected to expand the electrochemical stability window, the obtained PPy@NiCo-LDH@ITO NWs electrodes have a wide voltage range from 0 to 1.3 V, a maximum areal capacitance of 598 mF cm-2 at a scan rate of 5 mV s-1, and a capacitance retention rate of 83% after 10000 charge-discharge cycles, demonstrating the composite electrode has excellent long-term cycle stability. Benefit from the NiCo-LDH layered structure coated with PPy grown on ITO NWs and the WIS electrolyte with a wide voltage window, The assembled positive electrode PPy@NiCo-LDH@ITO NWs//negative electrode PPy@FeOOH@ITO NWs asymmetric MSCs have an operating voltage range of 0~2.5 V and a maximum areal capacitance of 63.04 mF cm-2, and it provides a high volume energy density of 32.2 mWh cm-3 when the power density is 294.1 mW cm-3. In addition, the series-parallel lighting test further proves the good consistency of the device.
(2) Laser etching technology assisted synthesis of membrane-free aqueous high-safety Zn//NiCo-LDH@ITO NWs@CC planar micro-zinc batteries. Based on manually manipulated carbon cloth (CC) and zinc foil (Zn), the conductivity and microstructural stability of NiCo-LDH was improved by using ITO NWs grown on CC (ITO NWs@CC) as current collectors through interfacial regulation. Afterwards, the ITO NWs@CC and Zn were respectively etched into two independent fingers of the same size by laser etching. NiCo-LDH was electrodeposited on the ITO NWs@CC finger to obtain the cathode NiCo-LDH@ITO NWs@CC, with Zn as the anode, and assembled into Zn// NiCo-LDH@ITO NWs@CC MBs on the glass slide with the aid of AB glue, conductive gel and CC wire. The three-dimensional ITO NWs@CC conductive network can increase the loading of active materials, facilitate the fast transfer of charges, and buffer the large expansion and contraction of active materials during long cycling, thereby improving the performance and lifetime of ZMBs. The aqueous ZMBs provided an areal capacity of 0.56 mAh cm-2 (453.5 mAh g-1), achieved a maximum energy density of 798.4 μWh cm-2 (649.9 Wh kg-1) and a power density of 4.1 mW cm-2 (3.29 W kg-1), exhibiting satisfactory rate performance (63.8% capacity retention from 1 mA cm-2 to 3 mA cm-2) and excellent cycling stability (101% capacity retention after 1000 cycles at 1 mA cm-2). In addition, the series-parallel and lighting tests of ZMBs illustrate the consistency of the devices. Therefore, the synthesis of fast and simple planar interdigitated ZMBs provides a reference for the next generation of high-performance, green-friendly and scalable planar micro-energy storage systems.
|MOST Discipline Catalogue
|理学 - 物理学 - 凝聚态物理
|李喜娟. 镍钴层状双氢氧化物的制备及其在微型储能器件中的应用研究[D]. 兰州. 兰州大学,2023.
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