兰州大学机构库 >材料与能源学院
以碳纳米纤维为模板生长纳米颗粒储能特性研究
Alternative TitleStudy on Energy Storage Properties of Growth of Nanoparticles Using Carbon Nanofibers as Templates
王煜
Subtype硕士
Thesis Advisor贺德衍
2023-08-27
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name工学硕士
Degree Discipline材料工程
Keyword超级电容器 Supercapacitors 静电纺丝 electrostatic spinning 掺氮碳纳米纤维 nitrogen-doped carbon nanofibers 电化学性能 electrochemical properties 纳米复合材料 nanocomposites
Abstract

中文摘要

实现“碳达峰”“碳中和”目标,能源产业是主战场,能量存储科学与技术成为了当今重要的研究方向,超级电容器作为代表性的能量存储器件有望应用于各个方面。随着电极材料的革新和应用功能的开发,超级电容器的发展已经走上了“快车道”。碳纳米纤维具有轻量化、低成本、绿色环保等优点,是制备超级电容器的理想材料之一。制约碳纳米纤维发展的主要因素是碳材料本身的容量具有局限性,需要通过复合其他材料来提升电极的电化学性能。

在本论文中,以掺氮碳纳米纤维复合材料作为研究对象,逐步实现对掺氮碳纳米纤维的设计制备、与金属纳米材料的复合、形貌优化、储能特性提升和实用化拓展等。通过设计基于掺氮碳纳米纤维复合材料的非对称超级电容器,获得了高的能量密度与功率密度。

(1)掺氮碳纳米纤维复合Ni-Cu纳米颗粒自支撑电极:通过静电纺丝结合退火碳化制备了掺氮碳纳米纤维,Ni-Cu纳米颗粒被成功地复合到纳米纤维上,纳米颗粒呈微球状,且与碳纤维附着紧密。氮掺杂碳纳米纤维具有高的导电性,纳米颗粒增大了复合材料作为电极的比表面积,使得离子传输、电子转移等性能更优异,从而改善了碳纳米纤维电极电化学性能。在电流密度为1 mA cm-2时,最优性能的CNFs/Ni-Cu-300电极的比容量为752.5 mF cm-2。基于CNFs/Ni-Cu-300电极和Ni-Co-S/NF电极组装的非对称超级电容器,在功率密度为6.99 × 10-2 W cm-2时,能量密度达到了1.24 × 10-2  Wh cm-2,且具有长循环稳定性,在循环5000次后器件的容量保持率达到了86.2%。

(2)保持碳纳米纤维结构,硫化制备掺氮碳纳米纤维与Ni-Cu-S复合材料:通过在硫气氛下对CNFs/Ni-Cu退火处理制备了CNFs/Ni-Cu-S复合材料,碳纳米纤维表面凹凸不平,呈现多级结构,增大了电极与电解液的接触面积。在电流密度为1 mA cm-2时,性能最佳的CNFs/Ni-Cu-S-300电极的比电容达到了1208 mF cm-2,同时表现出了良好的循环稳定性能。在5000次循环后电容容量为初始容量的76.5%。由于电极为自支撑电极,避免了传统电极活性材料与集流体附着力差、添加的非活性粘结剂和导电剂导致的活性材料利用率较低等问题。

(3)水热法制备掺氮碳纳米纤维与Ni-Co-S复合的自支撑电极:通过水热法在掺氮碳纳米纤维上制备了Ni-Co纳米棒及Ni-Co-S纳米颗粒。Ni-Co纳米棒的复合提升了电极与电解液的接触面积,有效增大了电极/电解液之间界面,提高了离子扩散和电子的传输速率。在电流密度为1 mA cm-2时,CNFs/Ni-Co电极比容量高达1316 mF cm-2。以Ni-Co-S/NF电极作为正极材料,CNFs/Ni-Co-S电极作为负极材料组装了非对称超级电容器,在功率密度为6.90 × 10-2 W cm-2时,器件的能量密度为7.00 × 10-3  Wh cm-2,在功率密度增大到3.12 × 10-1  W cm-2时,器件仍能保持5.90 × 10-4  Wh cm-2的能量密度。在5000次循环后容量保持率为72.6%,具有良好的倍率性能和循环稳定性。

Other Abstract

Abstract

The energy industry is the main battleground for achieving the goal of "emission peak" and "carbon neutrality", and energy storage science and technology has become an important research filed today. As a representative energy storage technology, supercapacitors are used in various aspects. With the innovation of electrode materials and the exploration of application functions, the development of supercapacitors has entered the "fast track". Carbon nanofibers can achieve the advantages of light weight, low cost, and environment-friendly, which is an ideal material for preparing supercapacitors. The main factor limiting the development of this material is the relative low electrochemical capacity of the carbon material, so the electrochemical performance needs to be enhanced by composite nanomaterials.

In this thesis, nitrogen-doped carbon nanofiber composites was investigated in terms of the different composite methods and enhancement of material properties, to realize the design and preparation of nitrogen-doped carbon nanofibers, composite methods of nanomaterials, morphology optimization, bonding methods, energy storage property enhancement and practical expansion. Based on the above experiments, the asymmetric supercapacitor using nitrogen-doped carbon nanofiber composites was designed to achieve high energy density and power density, and a feasible solution is proposed for the practical application of this material:

(1) Self-supporting electrode of nitrogen-doped carbon nanofiber composite Ni-Cu: nitrogen-doped carbon nanofiber substrate was prepared by electrostatic spinning and subsequent annealing carbonization, meanwhile, Ni-Cu nanoparticles were successfully compounded onto the nanofiber, and the nanoparticle was microspherical and tightly attached. The structure takes advantage of the high electrical conductivity of nitrogen-doped carbon nanofibers, while the nanoparticles increase the specific surface area of the electrode, and the combination results in better ion transport and electron transfer, thus improving the electrochemical properties of carbon nanofiber electrodes. The specific capacity of optimal performance electrodes CNFs/Ni-Cu-300 electrode is 752.5 mF cm-2 at a current density of 1 mA cm-2. The asymmetric supercapacitor assembled based on CNFs/Ni-Cu-300 electrode and Ni-Co-S/NF electrode achieves an energy density of 124.3 W h cm-2 at a power density of 6.99 × 10-2  W cm-2, and a long cycle stability, the device achieved 86.2% capacity retention after 5000 cycles.

(2) Preparation of CNFs/Ni-Cu-S nanocomposites by sulfidation of CNFs/Ni-Cu with maintained carbon nanofiber structure: the CNFs/Ni-Cu-S electrode was successfully prepared by annealing of CNFs/Ni-Cu under sulfur atmosphere, the Ni-Cu nanoparticles were sulfurized to obtain Ni-Cu-S nanoparticles with an uneven morphological surface and a multi-level structure, and this open structure can enhance the contact area between the electrode and the electrolyte. The area specific capacitance of the best performing electrode CNFs/Ni-Cu-S-300 electrode reached 1208 mF cm-2 at a current density of 1 mA cm-2, while exhibiting a good cycling stability performance. The capacitance capacity was 76.5% of the initial capacity after 5000 cycles. Since this electrode is a self-supporting electrode, it avoids the problems of poor adhesion of electrode materials and low utilization of active materials due to inactive binder and conductive agent, which exist in conventional collectors.

(3) CNFs/ Ni-Co-S self-supporting electrode via hydrothermal process of: Ni-Co nanorods and Ni-Co-S nanoparticles were successfully prepared on the nitrogen-doped carbon nanofiber substrate by hydrothermal method, and Ni-Co nanorods have obvious rod-like structure. The nanorods enhance the contact area between the electrode and electrolyte through the open structure, which effectively promotes the ion contact and ion diffusion and electron transport at the interface between the electrode/electrolyte. The specific capacity of the CNFs/Ni-Co electrode is as high as 1316 mF cm-2 at a current density of 1 mA cm-2. The asymmetric supercapacitor was assembled with Ni-Co-S/NF electrodes as the positive material and CNFs/Ni-Co-S electrodes as the negative material, and the device was able to maintain an energy density of 7.00× 10-3 W h cm-2 at a power density of 6.90 × 10-2  W cm-2 and 5.90× 10-4 W h cm-2 when the power density was increased to 3.12 × 10-1  W cm-2. The capacity retention rate was 72.6% after 5000 cycles, which shows good multiplicative performance and cycling stability.

Subject Area新能源材料与器件
MOST Discipline Catalogue工学 - 材料与化工 - 材料工程
URL查看原文
Language中文
Other Code262010_220200936791
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/538359
Collection材料与能源学院
Affiliation
兰州大学材料与能源学院
Recommended Citation
GB/T 7714
王煜. 以碳纳米纤维为模板生长纳米颗粒储能特性研究[D]. 兰州. 兰州大学,2023.
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