<p>Worldwide concern on fossil fuels
depletion and adverse impact on environment pushed researchers to find an
alternative energy source. Among various potential systems, electrochemical
energy storage devices have attracted significant attraction due to short
charge/discharge time, easy relocation, and relatively cheap cost compared to
large storage systems. Much research has been reported to suggest a material
for electrochemical storage systems. Carbon is a key part of human life in
terms of energy source, building materials, daily clothing and foods. The
extraordinary characteristics of carbon materials, including good conductivity,
good structure stability, relatively low cost, and sustainability, draw
interest to carbon application in energy storage systems. </p>
<p>The introduction of lithium ion batteries
(LIB), using graphite as an anode material, fulfilled the need of alternative
energy source and elevated the technologies into next level high-performance
applications such as portable devices. While the technology advancement in high
performance electronics fosters the development of advanced lithium ion
batteries, the introduction of electric vehicles and large intermittent systems
seeks energy storage devices with high capacity, sustainability, and low cost. In
this thesis, the impact of the characteristics of carbon material on energy
storage system performance is studied. The work presented in this thesis not
only suggests a cost-effective carbon synthesis for advanced LIB, but also
addresses how the carbon structure impact and resolves the systematic issue
associated with next generation energy storage systems.</p>
<p>Chapter 3 describes a facile, one-step,
solvent-free ‘dry autoclaving’ synthesis method utilizing coffee oil as the carbon
precursor to obtain micrometer diameter spheroidal carbon particles for lithium
ion battery anodes. The spheroidal morphology resulted from the evaporation of
liquid oil into a liquid/gas phase interphase at elevated temperature (700 <sup>o</sup>C),
followed by solid/gas sublimation interactions during cooling (below 350 <sup>o</sup>C)
in a closed autoclave. A mechanism of spheroidal carbon formation is proposed considering
the precursor’s composition and chemical interactions during autoclaving. The
prepared carbon from dry autoclave has shown successful LIB performance and
structure stability after 250 cycles.</p>
<p>Chapter
4 illustrates the temperature effect on the structure of biomass derived
carbon. In this study, due to its abundance and high
porosity, pistachio shells were selected as the primary carbon source and carbonized
at a range from 700 to 1500 °C. The temperature effect on carbon structure
was analyzed by XRD, Raman, BET, and electron microscopy. To propose an advanced
lithium ion battery, pistachio shell-derived carbon was applied as an anode
material for a sodium ion battery (SIB). The correlation of carbon structure
and SIB electrochemical performance is presented. Pistachio shell carbonized at
1000 °C resulted in highly amorphous structure with specific surface area
(760.9 m<sup>2</sup>/g) and stable cycle performance (225 mAh g<sup>-1</sup> at
10 mA g<sup>-1</sup>). With support from Raman, XRD, and BET, the storage
mechanism has been studied as well.</p>
<p> Chapter 5
describes the impact of carbon structure on resolving the polysulfide shuttling
effect in lithium sulfur (Li-S) batteries. Lithium sulfur batteries have
received tremendous attention due to its high theoretical capacity (1672 mAh g<sup>-1</sup>),
sulfur abundance, and low cost. However, main systemic issues, associated with
polysulfide shuttling and low Coulombic efficiency, hinder the practical use of
sulfur electrodes in commercial batteries. The work in this thesis demonstrated
an effective strategy of decorating nano-MnO<sub>2</sub> (less than 10 wt. %)
onto a sulfur reservoir in order to further capture the out-diffused
polysulfides via chemical interaction, and thereby improve the electrochemical
performance of sulfur electrodes without increasing the mass burden of the
total battery configuration. Pistachio shell-derived sustainable carbon (PC)
was employed as an effective sulfur container due to its structural
characteristics (interconnected macro channels and micropores). With the aids
of the structural benefits of PC scaffold and the uniform decoration of
nano-MnO<sub>2</sub>, the polysulfide shuttling effect was significantly
suppressed and cycling performance of a sulfur cathode was dramatically
improved over 250 cycles.</p>
This thesis offers a new prospect
in the study of carbon materials applications in various energy storage
systems. This concept can be further extended to other applications, such as
lithium metal batteries. The intercalation property of carbon structure can
reduce the local current density, reducing the risk of lithium dendrite growth,
which is the most critical issue of lithium metal battery.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/7789244 |
| Date | 15 May 2019 |
| Creators | Kyungho Kim (5929898) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/THE_STUDY_OF_CARBON_MATERIALS_FOR_ENERGY_STORAGE_SYSTEMS_FROM_SYNTHESIS_TO_STRUCTURE/7789244 |
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