CAS OpenIR
基于多层离子凝胶电解质的钠离子电容器
李伯森
Thesis Advisor张海涛, 陈群
2020-07-01
Degree Grantor中国科学院大学
Degree Name硕士
Degree Discipline化学工程
Keyword钠离子电容器,过渡金属氧化物,离子凝胶,界面稳定性,多物理场耦合
Abstract

随着传统化石能源的日益枯竭和气候变化的加剧,发展绿色、低碳及高效的可再生能源变得十分迫切。因此,与可再生能源匹配度极高的新型电化学储能技术的研发备受关注。钠离子电容器作为一种新型混合超级电容器,由于钠资源储量丰富、成本低、环境友好等特点而更适合于大规模储能,因此开发新型钠基储能器件成为当前热点。此外,安全性和体积限制使得研发固态钠离子电容器成为趋势。本论文主要围绕高性能固态钠离子电容器,在固态电解质和过渡金属氧化物电极的结构设计、储能机理、界面匹配及调控等方面开展了系统的研究。主要内容和成果如下:(1)针对非对称电容器正负极储能机制的不同,设计制备了兼具高离子迁移数层和高离子电导率层的非对称离子凝胶电解质,该双层离子凝胶电解质能有效促进电极/电解质界面的稳定性。此外,为了实现电极材料的动力学匹配,采用微波辅助溶剂热法制备了锐钛矿/青铜混合相二氧化钛纳米杂化电极(TiO2(A)/TiO2(B)@C/CNT)。多壁碳纳米管(MWCNTs)为二氧化钛提供了丰富的结晶位点,获得高比表面积的片状阵列,缩短了钠离子的传输距离,并通过无定形碳包覆有效提高电极的导电特性。双动力学匹配的钠离子电容器实现了低界面电阻,最大能量密度达94.8 Wh·kg-1,超长稳定循环达10000圈,容量保持率为82.4%。该研究为混合电容器的动力学匹配问题提供了一个有效的解决方案。(2)采用具有高热稳定性能的聚丙烯腈(PAN)、聚亚酰胺(PI)作为基质,以离子液体为增塑剂,构筑高压高热稳定性双层离子凝胶电解质。具有高抗氧化性的PAN层与活性炭阴极形成了稳定的高压界面,将器件的工作电压有效拓展至4.5 V。随后,经过剥离-自卷曲过程制备出T-Nb2O5/rGO纳米杂化电极,负载的还原氧化石墨烯(rGO)有效提高了电极的电子传导能力。T-Nb2O5纳米管与高比表面积的还原氧化石墨烯的紧密结合充分提升了纳米杂化电极的动力学特性。组装的高压高温钠离子电容器在90 ℃下提供能量密度为109.9 Wh·kg-1,循环6000次后容量保持率为91.4%。(3)采用基于有限元方法的COMSOL Multiphysics软件模拟了钠离子电容器内部电解质离子分布和电压分布。通过分析钠离子分布得出,高离子迁移数层能够有效缓解负极/电解质界面的浓度梯度和极化,进一步揭示了动力学匹配双层离子凝胶电解质的工作原理。通过电压分布模拟,促进了对高压层有效厚度的优化设计,提高实验效率。;The development of next-generation large-scale energy storage techniques is being stimulated by an increasing demand in sustainable and renewable energy resources due to climate change and the lack of enough fossil fuels. Sodium-ion capacitors(SICs) have attracted extensive attentions due to the availability of abundant cheap, environmental friendly sodium resources. Meanwhile, security risks and volume restrictions of energy storage devices have stimulated the study of solid-state sodium-ion capacitors. This thesis will be focusing on the construction of high performance high-voltage solid-state sodium-ion capacitors. In particularly, the studies on structure design, energy storage mechanism and solid electrolyte interface matching of solid electrolyte and electrodes have been performed systemically. Detailed outcomes are presented as follows:(1) An asymmetric ionogel electrolyte was constructed to provide stable electrode/electrolyte interfaces on account of the different energy storage mechanisms of opposite electrodes. In addition, anatase/bronze mixed phase titanium dioxide nanohybrid electrode, TiO2(A)/TiO2(B)@C/CNT, has been prepared by a microwave-assisted solvothermal method. Abundant crystallization sites for titanium dioxide were provided by multiwalled carbon nanotubes (MWCNTs). A high specific-surface-area nanosheet arrays coated with an amorphous carbon layer were obtained. The modification could improve effectively the conductivity of the electrode and shorten the transport distance of sodium ions. Owing to the double kinetic-matchings design, a sodium-ion capacitor could exhibit a high energy density of 94.8 Wh·kg-1 and an ultra-long-term ability of 10000 cycles with a capacity retention rate of 82.4%. This work provides a new strategy to design hybrid capacitors incorporating the electrodes with diverse ion storage mechanisms.(2) A high thermally stable ionogel electrolyte was constructed by employing thermally stable PAN and PI as the matrix and ionic liquid as plasticizer. Such an electrolyte would provide a possibility of tolerating high temperature. Note that PAN layer with a high oxidation resistance could provide a stable high-voltage interface with the activated carbon cathode, and effectively expand the working voltage of SICs up to 4.5 V. In addition, the T-Nb2O5/rGO nanohybrid electrode was prepared by an exfoliation-rolling process, its conductivity was improved effectively due to the presence of reduced graphene oxide nanosheets. The combination of nanotubes and high specific-surface-area reduced graphene enhanced the kinetic characteristics of T-Nb2O5/rGO. At 90 ℃, optimized SIC could provide an ultra-high energy density of 109.9 Wh·kg-1, and a capacity retention rate maintained 91.4% after 6000 cycles.(3) A finite element method, based on the COMSOL Multiphysics software, was used to simulate the ion distribution and voltage distribution in a sodium-ion capacitor. The PDADMATFSI layer was proved to be able to alleviate effectively the concentration gradient and polarization at the anode/electrolyte interface by simulating the distribution of sodium ions. The thickness of the PAN layer was optimized through the simulation of voltage distribution. 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/49726
Collection中国科学院过程工程研究所
Recommended Citation
GB/T 7714
李伯森. 基于多层离子凝胶电解质的钠离子电容器[D]. 中国科学院大学,2020.
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