物理化学学报 >> 2019, Vol. 35 >> Issue (7): 734-739.doi: 10.3866/PKU.WHXB201806063

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基于共价有机框架复合材料的锂硒电池应用

李路路,姚路,段力*()   

  • 收稿日期:2018-06-28 发布日期:2018-12-21
  • 通讯作者: 段力 E-mail:franklinduan@sjtu.edu.cn
  • 基金资助:
    国家自然科学基金(61376003)

Application of Lithium-Selenium Batteries Using Covalent Organic Framework Composite Cathodes

Lulu LI,Lu YAO,Li DUAN*()   

  • Received:2018-06-28 Published:2018-12-21
  • Contact: Li DUAN E-mail:franklinduan@sjtu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(61376003)

摘要:

本文利用溶剂热反应方法,在多壁碳纳米管(MWCNTs)管壁上生长了共价有机框架(TpPa-COF)材料,并将这种核壳多壁碳纳米管/共价有机框架纳米复合材料(MWCNTs@TpPa-COF)成功应用在锂硒电池上。利用场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)和傅里叶变换红外光谱(FT-IR)等手段对材料结构进行表征,结果表明多壁碳纳米管和共价有机框架材料成功复合。电化学测试结果表明,该材料在电流密度3C (1C = 675 mA∙g−1)下的质量比容量为463.5 mAh∙g−1,500次循环后能保持99%的库仑效率,表明锂硒电池具有优异的循环稳定性和较长的循环寿命。

关键词: 锂硒电池, 多壁碳纳米管, 共价有机框架, 纳米复合材料, 核壳结构

Abstract:

Li-S batteries are considered promising next-generation energy storage systems because they offer high theoretical specific capacity (1675 mAh∙g−1), high energy density (2600 Wh∙kg−1), environmental friendliness, and low cost. However, large-scale commercial applications are hindered by the low electrical conductivity of S, high volume expansion ratio, and high solubility of intermediate polysulfides in organic electrolytes. Li-Se batteries using Se as the cathode material have high discharge rates, good cyclic performance, high electrical conductivities, high output voltages, and high volumetric capacity densities, and therefore, they are potential alternatives to Li-S systems. Recently, covalent organic frameworks (COFs) have emerged as new porous crystalline materials with large specific surface areas, high porosities, low densities, good thermal stabilities, and controllable structures. Therefore, COFs have wide potential applicability in the fields of gas adsorption, heterogeneous catalysis, energy storage, and drug delivery. Based on the above analysis, a simple core-shell multiwalled carbon nanotube (MWCNT)/1, 3, 5-triformylphloroglucinol (Tp)-phenylenediamine (Pa) COF nanocomposite (MWCNT@TpPa-COF) was prepared by growing a TpPa-COF on MWCNTs through a simple solvothermal reaction. The MWCNT@TpPa-COF high-performance cathode material realizes the first application of a COF in Li-Se batteries. The MWCNTs can encapsulate Se, limit the diffusion of polyselenides (Li2Sen, 3 ≤ n ≤ 8), and provide rapid electron conduction and ion transmission. In addition, the π-π interaction between MWCNTs and COFs promotes COF growth and distribution on the MWCNTs, thereby forming core-shell MWCNT@TpPa-COF nanocomposites, which can further increase the loading of Se. Measurements via field-emission scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy confirmed the successful combination of MWCNTs and COFs. The rich micro- and mesoporous hierarchical structure provides the MWCNT@TpPa-COF nanocomposites with initial specific discharge capacities reaching 463.5 mAh∙g−1 at the current density of 3C (1C = 675 mA∙g−1). Cells utilizing the nanocomposite electrodes maintained 99% Coulombic efficiency, with the average cyclic capacitive loss of 0.14% after 500 cycles. In addition, electrochemical impedance spectroscopy, cyclic voltammetry, and multiple-rate cycling analyses support the excellent electrochemical performance of the proposed cathode material. This work provides a promising new prospect for the future development of rechargeable Li-Se batteries utilizing new COF-based cathode materials.

Key words: Lithium-selenium battery, Multi-walled carbon nanotube, Covalent organic frameworks, Nanocomposites, Core-shell structure

MSC2000: 

  • O646