196,117 research outputs found
The study of policy coordination: an approach to integrate expert assessment with automated content analysis
No full textPublic policy scholars have long agreed that the coordination of policies involving different authorities and policy frameworks is challenging.This paper responds to recent calls to explore new empirical methods for studying policy coordination by integrating automated text analysis into the workflow of human experts. A key contribution of our approach is a quantitative indicator of the semantic alignment between different policy objectives. We critically review the performance of the indicator in terms of its ability to assess both horizontal and vertical policy coordination by analysing the Recovery and Resilience Plan (2021-26) and the national and regional Smart Specialization Strategies (2021-27) in Portugal. Based on this exercise, we reflect on the necessary conditions for the successful implementation of automated text analysis of policy documents as well as its potential in other empirical settings.The work of S.K. was supported by the KU Leuven Impulsfund (grant number IMP/20/002)
Implementing Smart Specialisation Strategies Analysis of the Role of Regional Strategies in National Innovation Strategies
No full textSmart specialisation (RIS3) is a placed-based policy approach aiming to boost Europe’s
innovative potential by enabling each region to identify and develop its own competitive
advantages. It is based on an entrepreneurial discovery process and the selection of a
limited number of thematic priorities, allowing policy makers to address emerging
opportunities and market developments in a coherent manner, while avoiding duplication
and fragmentation of efforts across regions. The Smart Specialisation Strategies may take
the form of, or be included in, a national or regional research and innovation (R&I) strategic
policy framework. The adoption of national and/or regional Smart Specialisation Strategies
was a formal requirement for allocating R&I budgets from the European Structural and
Investment Funds.
The objective of the present report is to analyse the progress of Member States in the
implementation of national and regional smart specialisation strategies, in particular by
means of an assessment of new policy developments, the progress of implementation of
the different strategies, the monitoring mechanisms and observed impacts. This
assessment mainly relied on the information contained in the Research and Innovation
Observatory (RIO) country reports 2017 and through a survey conducted among the RIO
network experts. This input was complemented by data gathered through the Eye@RIS3
platform, the European Innovation Scoreboard 2017 and the Regional Innovation
Scoreboard (2017).The authors express their gratitude to Marek Przeor from DG REGIO and national experts in JRC’s Research and Innovation Observatory network, whose inputs were analyzed in this report. Furthermore, the Eye@RIS3 tool developed by the JRC’s Smart Specialisation Platform is acknowledged as an essential source of data on national and regional RIS3 priorities in Europe
Advancement of solid-state batteries through the understanding of cathode-solid electrolyte interactions
No full textThe aim of this thesis was to obtain fundamental insights in the interaction
between the polymeric eutectogel (P-ETG) and NMC622 positive electrode
materials on the one hand, and obtaining expertise in the integration of the P-ETG
electrolyte in solid-state batteries on the other hand, with the final goal the
realization of a high-performance positive electrode for solid-state batteries.
The flexible P-ETG electrolytes were introduced by Joos et al. at the DESINe
group (UHasselt) as a hybrid solid-state electrolyte in which a lithium-ion
conducting deep eutectic solvent (DES) is confined within a polymeric backbone.
They demonstrate a broad electrochemical stability window (1.5 − 4.5 V vs. Li+/Li)
and a high ionic conductivity at room temperature (0.76 mS cm−1). Therefore, the
P-ETG holds potential as an inexpensive and flexible electrolyte for the nextgeneration solid state Li-ion batteries with high-potential positive
electrode materials. Given the availability of this interesting candidate solid
electrolyte, the bottleneck of solid-state battery development today is not only
limited to maximize the ionic conductivity. Another main issue of solid-state
batteries is the integration of the solid-state electrolyte and electrodes.
The challenge of cell integration is associated mainly with maintaining chemical
and mechanical stability between the electrodes and the solid-state electrolyte
during battery operation, besides controlling the properties of the
electrode/electrolyte interface. A good interface between a solid electrolyte and
electrode requires fast ion transport, optimum contact area, and chemical stability
during cycling. However, experimentally, it was found that the reported P-ETG
containing 4-acryloyl morpholine (ACMO) backbone units has limited chemical
stability in contact with high-potential positive electrode materials, such as
NMC622. Therefore, the already existing P-ETG needed to be optimized to be
electrochemical compatible with the commercially relevant NMC622 positive
electrode materials.
Chapter 3 is was seen that the (electro)chemical compatibility between solid
electrolyte and positive electrode active material is very important and
has a significant effect on the battery performance. The incompatibility between
the ACMO-based P-ETG and high-nickel NMC622 positive electrode material,
resulting in fast capacity fading, was tackled by adapting the polymer backbone.
To this end, replacing the ACMO backbone with N-isopropyl acrylamide (NIPAM)
was successful. The NIPAM was selected because it does not contain any ether functions, which was hypothesized to be responsible for limiting the cycle life in
combination with high-energy, positive electrodes. This NIPAM-based P-ETG
shows interesting properties, such as relatively high ionic conductivity (0.82 mS
cm-1) and a broad electrochemical stability window (1.5 – 5.0 V vs. Li+/Li). The PETG also displays a higher thermal stability compared to conventional liquid
electrolytes (i.e., 1 M LiPF6 in EC/EMC (3/7) + 2% VC), leading to a suppressed
flammability which results in increased safety in the use of a battery applications,
such as electric vehicles. Physico-chemical characterization techniques, such as
PXRD, ATR-FT-IR, ICP-AES, and EIS, indicated that the NIPAM-based P-ETG
electrolyte and NMC622 active positive electrode material are chemically
compatible. However, a chemical instability of the P-ETG-85/Li interface leads to
the formation of resistant films. The Li|NMC622 coin cells assembled with this
NIPAM-based P-ETG as the electrolyte were found to deliver a capacity of 134,
110, and 97 mAh g-1 over 90 cycles at C/5, C/2, and 1C. The coulombic efficiency
is exceeding 95% for C/5, C/2, and 1C. In contrast to the former generation of PETG, which had the limitation that it could only function in conjunction with
LiFePO4, a low energy density cathode material, our novel composition of P-ETG
overcomes this limitation and elevates the P-ETG up to the league of the realworld high voltage batteries built with high Ni-NMC, such as NMC622. In
conclusion, the NIPAM-based P-ETG shows a great promise as an
inexpensive and safe electrolyte for the next generation solid state Li/Li-ion
batteries.
Nonetheless, further research was performed in chapter 4 to develop new stateof-the-art P-ETGs focussing on the interaction of the polymeric framework
and the enclosed DES. The properties of polymeric backbone eutectogel (P-ETG)
electrolytes for LIBs, created by DES confined inside various polymeric networks
are studied. Different P-ETG compositions were synthesized by varying the
monomer and crosslinker. The aim of this chapter was to study the effect of the
monomer and crosslinker by obtaining a more in-depth knowledge on the
interaction between the polymer and the DES. First, it was found that the
composition of the DES plays an important role on its electrochemical properties.
The improved anodic stability of DES composition with high LiTFSI concentrations
indicates that also in the Li-based DES hydrogen bonds between MAc molecules
are replaced with strong ionic interactions between MAc, Li+ and TFSI-
, lowering
the concentration of free and electrochemically unstable MAc molecules. Secondly,
the DES was incorporated into a polymer matrix. LSV and NMR experiments
indicated that the incorporation of the DES into the polymeric matrix affects the
interaction of LiTFSI and MAc inside the DES. To obtain a P-ETG with a high ionic
conductivity and anodic stability, a high vol% DES is necessary. Thirdly, varying
the type of functional groups in the polymeric backbone (monomer or crosslinker)
resulted in limited changes in interactions between DES and the various polymeric
backbones according to NMR spectroscopy. However, this could be explained by
the fact that only acrylamide-based monomers were studied. In future work, the
properties of the P-ETG electrolytes could be improved to facilitate the transport
of more Li+ ions by investigating the effect of immobilization of the DES components, such as MAc and TFSI- by means of hydrogen bonding to functional
groups present in the polymeric backbone matrix.
In a second part of chapter 4, the effect of the various P-ETGs on the
electrochemical properties was studied. The ionic conductivities depend on the
monomer and crosslinker, reaching values from 0.400 mS cm-1
for ACMO-EGDMA
to 1.011 mS cm-1
for DEAA-EGDMA at 25°C. The choice of the crosslinker has a
significant effect on the ionic conductivity as amides (MBAA) result in less mobile
chains compared to esters (EGDMA) due to increased rotational barriers in MBAA,
a shorter chain length, and the possibility of the MBAA N-H to hydrogen bond with
MAc, all reducing the mobility of the DES in the polymeric matrix. Using several
P-ETGs as the electrolyte, the Li | NMC622 coin cells were assembled. The
cells demonstrated initial specific discharge capabilities of 163, 136, 136, and 24
mAh g-1 at C/10 for NIPAM, HEAA, DEAA, and ACMO in combination with MBAA
crosslinker, making the NIPAM-MBAA P-ETG composition the most promising
electrolyte. EIS indicated that the P-ETGs with the NIPAM, HEAA, and DEAA
backbones are electrochemically compatible with high-voltage NMC622 active
positive electrode materials. However, resistant surface films arise as a result of
the chemical instability of all P-ETG | Li interfaces, limiting the life-time of the
batteries.
However, the development of solid-state batteries is not only limited to the
development of new solid electrolytes. The replacement of the conventional liquid
electrolyte by the solid electrolytes also introduces new challenges for cell
production processes, and its steps need to be adapted or even redesigned. In
the previous chapters, we showed that the P-ETG shows a great promise as an
inexpensive and safe electrolyte for the next generation solid state Li/Li-ion
batteries. Nonetheless further research was required to investigate the long-term
stability of the solid-solid contacts between the P-ETG and the electrodes by
improving the processing method and developing a composite electrode
containing the NMC622 active material and P-ETG electrolyte.
For commercial application of solid electrolytes and their electrodes for high
capacity solid-state batteries, a wet/solution process using a slurry coating
method is preferable. The aim of chapter 5 was the preparation of a composite
positive electrode for high-energy density Li-ion batteries by infiltrating the P-ETG
electrolyte precursor into the pores of the positive electrode. Knowledge was
obtained on the realisation of the composite positive electrode, and performance
limiting factors, such as electrolyte thickness, positive electrode active material
loading, porosity, and electrolyte composition. The preparation of a composite
positive electrode for high-energy density lithium-ion batteries was studied by
infiltrating the liquified P-ETG electrolyte into the pores of the positive
electrode. The P-ETG solution infiltration shows uniform distribution of the P-ETG
electrolyte inside the pores of the NMC622 positive electrode, even deep inside
the electrode. This solution infiltration process, called the in-situ synthesis
method, enables the formation of intimate ionic contacts between electrodes and
electrolyte as well as densification the positive electrodes. Long-term cycling tests
verify the reliability of the P-ETG-infiltrated composite NMC622 electrodes in Li NMC622 coin cells. However, increasing the areal capacity of the NMC622 positive
electrode from 0.11 mAh cm-2
to 0.61 mAh cm-2
resulted in significant capacity
fading which could be explained by the stability issues between our P-ETG
electrolyte and the Li metal anode at higher current densities. A stable discharge
capacity was obtained by using LTO negative electrode materials and the in-situ
synthesis method for the P-ETG electrolyte resulting in a more stable
discharge capacity with an initial discharge capacity of 110 mAh g-1
, and 76.6%
of the initial capacity is remained after 90 cycles, compared to 56.8% for the noninfiltrated NMC622 positive electrodes. The effect of the positive electrode porosity
and electrolyte thickness was studied using design of experiments. It could be
seen that the effect of the electrode porosity was not significant, but the
electrolyte thickness has a significant effect on the initial discharge capacity.
Decreasing the electrolyte thickness results in higher initial discharge capacities.
The effect of the polymeric backbone on the battery performance using the in-situ
P-ETG synthesis method developed in this work was studied in LTO | P-ETG |
NMC622 cells. It was seen that the DEAA-MBAA monomer-crosslinker combination
resulted in the highest and most stable discharge capacity at all C-rates, with even
a discharge capacity around 20 mAh g-1 at 3C. Therefore, it is concluded that in
this chapter knowledge was obtained on the realisation of a promising composite
positive electrode for the use in the next-generation solid state Li-ion batteries.
Increasing the areal capacity of the NMC622 positive electrodes even further to
0.98 mAh cm-2
resulted in a decreased discharge capacity. Possible issues that
could explain this reduced discharge capacity could be the poor conduction in the
positive electrode or conduction over the interphase between electrode and
electrolyte. To solve this issue, the P-ETG electrolyte could also be processed
in the electrode slurry. This could result in a higher, and more homogeneous
Li-ion conduction in the positive electrode, combined with a better interphase
contact between electrode and electrolyte. Although there is lots of experience in
processing of porous electrode sheets for lithium-ion battery applications with
conventional liquid electrolytes, there is little experience in processing of compact
electrodes optimized for solid-state batteries. One of the challenges is the
formulation of a slurry recipe containing the active material and the solid
electrolyte. Many parameters of the electrode fabrication process have an
influence on the final battery performance, which makes the electrode fabrication
process a critical and complicated step in battery assembly. Therefore, the last
aim of this thesis was the preparation of a composite positive electrode for highenergy density lithium-ion batteries by the development of one-pot method in
which the NMC622 active material, the P-ETG precursor solution electrolyte, and
carbon additives are mixed and tape-casted onto a current collector. Different
processing procedures were tested in this work, and knowledge on the slurry
recipe and processing parameters was be obtained by studying the effect of the
loading of the active material and solid electrolyte in the composite positive
electrode. One important finding was that the polymerization of the P-ETG
processed in the positive electrode was hindered by the presence of carbon black.
To solve this issue, the UV-initiator was replaced by a thermal-initiator, allowing
to start the polymerization by a heat pulse. However, this thermal polymerization step was responsible for the loss of a part of the MAc in the DES. Applying the insitu synthesis method to fill the pores of the positive electrodes with P-ETG
precursor, made it possible to obtain dense positive electrodes. The performance
was tested in LTO | P-ETG | NMC66 cells, resulting in reasonably high and stable
discharge capacities for 30 cycles. Almost all composition of positive electrodes
synthesized using the one-pot method, mixing the NMC622 active material and PETG electrolyte, result in a high initial discharge capacity compared to the
infiltrated NMC622 electrodes using the in-situ synthesis method described in
chapter 5. This indicates the importance of the processing of the solid electrolyte
inside the electrode. Decreasing the NMC622 active material loading resulted in
the highest discharge capacity. However, increasing the NMC622 active material
loadings resulted in a decreased initial discharge capacity, indicating the
complexity of an electrode preparation process and the importance of the
knowledge on the performance limiting factors. Therefore, additional research on
the processing of on-pot positive electrodes containing the NMC622 active
material and the P-ETG electrolyte is needed to identify the processing limiting
factors and to improve the NMC622 active material loading, discharge capacity
and cycle life of the cell.
2. Impact for battery/solid electrolyte community
Since the publication of the first silica-based eutectogel as a new class of solid
composite electrolytes by Joos and co-workers [1] in 2018, there has been an
increase in research into the use of liquid DES electrolytes as non-flammable,
hybrid solid-state electrolytes for lithium-ion batteries. Especially, the introduction
of the polymer-based eutectogel electrolytes showed a great potential due to their
facile synthesis method and promising properties, such as a high ionic conductivity
at room temperature and relatively broad electrochemical stability window. [2]
Many compositions of DES-containing hybrid electrolytes were described in
literature during the past years. [3]–[8] However, most publications focus only on
the development of a new electrolyte composite and its properties, such as
increasing the ionic conductivity even to higher values. This are indeed very
interesting and needed topics, however, given the availability of many promising
solid electrolytes, the bottleneck of solid-state battery development is no longer
to maximize the ionic conductivity or the anodic stability limit. The main issue has
now shifted towards the integration of the solid electrolyte and the electrode
materials in a battery. This PhD focusses on the combination of the synthesis of
the P-ETG electrolyte and its integration within a porous electrode, which is mostly
overlooked in the existing literature.
A part of the results presented in chapter 3 and 4, resulted in two peer-reviewed
publications, indicating its scientific relevance for the battery field and its possible
contribution to the development of the next generation solid-state batteries.
In summary, the work presented in this PhD thesis provides valuable insights for
the battery and solid electrolyte community for the development of P-ETG as solid
electrolytes, focussing both on their design and their integration into a battery
Advancement of solid-state batteries through the understanding of cathode-solid electrolyte interactions
No full textThe aim of this thesis was to obtain fundamental insights in the interaction
between the polymeric eutectogel (P-ETG) and NMC622 positive electrode
materials on the one hand, and obtaining expertise in the integration of the P-ETG
electrolyte in solid-state batteries on the other hand, with the final goal the
realization of a high-performance positive electrode for solid-state batteries.
The flexible P-ETG electrolytes were introduced by Joos et al. at the DESINe
group (UHasselt) as a hybrid solid-state electrolyte in which a lithium-ion
conducting deep eutectic solvent (DES) is confined within a polymeric backbone.
They demonstrate a broad electrochemical stability window (1.5 − 4.5 V vs. Li+/Li)
and a high ionic conductivity at room temperature (0.76 mS cm−1). Therefore, the
P-ETG holds potential as an inexpensive and flexible electrolyte for the nextgeneration solid state Li-ion batteries with high-potential positive
electrode materials. Given the availability of this interesting candidate solid
electrolyte, the bottleneck of solid-state battery development today is not only
limited to maximize the ionic conductivity. Another main issue of solid-state
batteries is the integration of the solid-state electrolyte and electrodes.
The challenge of cell integration is associated mainly with maintaining chemical
and mechanical stability between the electrodes and the solid-state electrolyte
during battery operation, besides controlling the properties of the
electrode/electrolyte interface. A good interface between a solid electrolyte and
electrode requires fast ion transport, optimum contact area, and chemical stability
during cycling. However, experimentally, it was found that the reported P-ETG
containing 4-acryloyl morpholine (ACMO) backbone units has limited chemical
stability in contact with high-potential positive electrode materials, such as
NMC622. Therefore, the already existing P-ETG needed to be optimized to be
electrochemical compatible with the commercially relevant NMC622 positive
electrode materials.
Chapter 3 is was seen that the (electro)chemical compatibility between solid
electrolyte and positive electrode active material is very important and
has a significant effect on the battery performance. The incompatibility between
the ACMO-based P-ETG and high-nickel NMC622 positive electrode material,
resulting in fast capacity fading, was tackled by adapting the polymer backbone.
To this end, replacing the ACMO backbone with N-isopropyl acrylamide (NIPAM)
was successful. The NIPAM was selected because it does not contain any ether functions, which was hypothesized to be responsible for limiting the cycle life in
combination with high-energy, positive electrodes. This NIPAM-based P-ETG
shows interesting properties, such as relatively high ionic conductivity (0.82 mS
cm-1) and a broad electrochemical stability window (1.5 – 5.0 V vs. Li+/Li). The PETG also displays a higher thermal stability compared to conventional liquid
electrolytes (i.e., 1 M LiPF6 in EC/EMC (3/7) + 2% VC), leading to a suppressed
flammability which results in increased safety in the use of a battery applications,
such as electric vehicles. Physico-chemical characterization techniques, such as
PXRD, ATR-FT-IR, ICP-AES, and EIS, indicated that the NIPAM-based P-ETG
electrolyte and NMC622 active positive electrode material are chemically
compatible. However, a chemical instability of the P-ETG-85/Li interface leads to
the formation of resistant films. The Li|NMC622 coin cells assembled with this
NIPAM-based P-ETG as the electrolyte were found to deliver a capacity of 134,
110, and 97 mAh g-1 over 90 cycles at C/5, C/2, and 1C. The coulombic efficiency
is exceeding 95% for C/5, C/2, and 1C. In contrast to the former generation of PETG, which had the limitation that it could only function in conjunction with
LiFePO4, a low energy density cathode material, our novel composition of P-ETG
overcomes this limitation and elevates the P-ETG up to the league of the realworld high voltage batteries built with high Ni-NMC, such as NMC622. In
conclusion, the NIPAM-based P-ETG shows a great promise as an
inexpensive and safe electrolyte for the next generation solid state Li/Li-ion
batteries.
Nonetheless, further research was performed in chapter 4 to develop new stateof-the-art P-ETGs focussing on the interaction of the polymeric framework
and the enclosed DES. The properties of polymeric backbone eutectogel (P-ETG)
electrolytes for LIBs, created by DES confined inside various polymeric networks
are studied. Different P-ETG compositions were synthesized by varying the
monomer and crosslinker. The aim of this chapter was to study the effect of the
monomer and crosslinker by obtaining a more in-depth knowledge on the
interaction between the polymer and the DES. First, it was found that the
composition of the DES plays an important role on its electrochemical properties.
The improved anodic stability of DES composition with high LiTFSI concentrations
indicates that also in the Li-based DES hydrogen bonds between MAc molecules
are replaced with strong ionic interactions between MAc, Li+ and TFSI-
, lowering
the concentration of free and electrochemically unstable MAc molecules. Secondly,
the DES was incorporated into a polymer matrix. LSV and NMR experiments
indicated that the incorporation of the DES into the polymeric matrix affects the
interaction of LiTFSI and MAc inside the DES. To obtain a P-ETG with a high ionic
conductivity and anodic stability, a high vol% DES is necessary. Thirdly, varying
the type of functional groups in the polymeric backbone (monomer or crosslinker)
resulted in limited changes in interactions between DES and the various polymeric
backbones according to NMR spectroscopy. However, this could be explained by
the fact that only acrylamide-based monomers were studied. In future work, the
properties of the P-ETG electrolytes could be improved to facilitate the transport
of more Li+ ions by investigating the effect of immobilization of the DES components, such as MAc and TFSI- by means of hydrogen bonding to functional
groups present in the polymeric backbone matrix.
In a second part of chapter 4, the effect of the various P-ETGs on the
electrochemical properties was studied. The ionic conductivities depend on the
monomer and crosslinker, reaching values from 0.400 mS cm-1
for ACMO-EGDMA
to 1.011 mS cm-1
for DEAA-EGDMA at 25°C. The choice of the crosslinker has a
significant effect on the ionic conductivity as amides (MBAA) result in less mobile
chains compared to esters (EGDMA) due to increased rotational barriers in MBAA,
a shorter chain length, and the possibility of the MBAA N-H to hydrogen bond with
MAc, all reducing the mobility of the DES in the polymeric matrix. Using several
P-ETGs as the electrolyte, the Li | NMC622 coin cells were assembled. The
cells demonstrated initial specific discharge capabilities of 163, 136, 136, and 24
mAh g-1 at C/10 for NIPAM, HEAA, DEAA, and ACMO in combination with MBAA
crosslinker, making the NIPAM-MBAA P-ETG composition the most promising
electrolyte. EIS indicated that the P-ETGs with the NIPAM, HEAA, and DEAA
backbones are electrochemically compatible with high-voltage NMC622 active
positive electrode materials. However, resistant surface films arise as a result of
the chemical instability of all P-ETG | Li interfaces, limiting the life-time of the
batteries.
However, the development of solid-state batteries is not only limited to the
development of new solid electrolytes. The replacement of the conventional liquid
electrolyte by the solid electrolytes also introduces new challenges for cell
production processes, and its steps need to be adapted or even redesigned. In
the previous chapters, we showed that the P-ETG shows a great promise as an
inexpensive and safe electrolyte for the next generation solid state Li/Li-ion
batteries. Nonetheless further research was required to investigate the long-term
stability of the solid-solid contacts between the P-ETG and the electrodes by
improving the processing method and developing a composite electrode
containing the NMC622 active material and P-ETG electrolyte.
For commercial application of solid electrolytes and their electrodes for high
capacity solid-state batteries, a wet/solution process using a slurry coating
method is preferable. The aim of chapter 5 was the preparation of a composite
positive electrode for high-energy density Li-ion batteries by infiltrating the P-ETG
electrolyte precursor into the pores of the positive electrode. Knowledge was
obtained on the realisation of the composite positive electrode, and performance
limiting factors, such as electrolyte thickness, positive electrode active material
loading, porosity, and electrolyte composition. The preparation of a composite
positive electrode for high-energy density lithium-ion batteries was studied by
infiltrating the liquified P-ETG electrolyte into the pores of the positive
electrode. The P-ETG solution infiltration shows uniform distribution of the P-ETG
electrolyte inside the pores of the NMC622 positive electrode, even deep inside
the electrode. This solution infiltration process, called the in-situ synthesis
method, enables the formation of intimate ionic contacts between electrodes and
electrolyte as well as densification the positive electrodes. Long-term cycling tests
verify the reliability of the P-ETG-infiltrated composite NMC622 electrodes in Li NMC622 coin cells. However, increasing the areal capacity of the NMC622 positive
electrode from 0.11 mAh cm-2
to 0.61 mAh cm-2
resulted in significant capacity
fading which could be explained by the stability issues between our P-ETG
electrolyte and the Li metal anode at higher current densities. A stable discharge
capacity was obtained by using LTO negative electrode materials and the in-situ
synthesis method for the P-ETG electrolyte resulting in a more stable
discharge capacity with an initial discharge capacity of 110 mAh g-1
, and 76.6%
of the initial capacity is remained after 90 cycles, compared to 56.8% for the noninfiltrated NMC622 positive electrodes. The effect of the positive electrode porosity
and electrolyte thickness was studied using design of experiments. It could be
seen that the effect of the electrode porosity was not significant, but the
electrolyte thickness has a significant effect on the initial discharge capacity.
Decreasing the electrolyte thickness results in higher initial discharge capacities.
The effect of the polymeric backbone on the battery performance using the in-situ
P-ETG synthesis method developed in this work was studied in LTO | P-ETG |
NMC622 cells. It was seen that the DEAA-MBAA monomer-crosslinker combination
resulted in the highest and most stable discharge capacity at all C-rates, with even
a discharge capacity around 20 mAh g-1 at 3C. Therefore, it is concluded that in
this chapter knowledge was obtained on the realisation of a promising composite
positive electrode for the use in the next-generation solid state Li-ion batteries.
Increasing the areal capacity of the NMC622 positive electrodes even further to
0.98 mAh cm-2
resulted in a decreased discharge capacity. Possible issues that
could explain this reduced discharge capacity could be the poor conduction in the
positive electrode or conduction over the interphase between electrode and
electrolyte. To solve this issue, the P-ETG electrolyte could also be processed
in the electrode slurry. This could result in a higher, and more homogeneous
Li-ion conduction in the positive electrode, combined with a better interphase
contact between electrode and electrolyte. Although there is lots of experience in
processing of porous electrode sheets for lithium-ion battery applications with
conventional liquid electrolytes, there is little experience in processing of compact
electrodes optimized for solid-state batteries. One of the challenges is the
formulation of a slurry recipe containing the active material and the solid
electrolyte. Many parameters of the electrode fabrication process have an
influence on the final battery performance, which makes the electrode fabrication
process a critical and complicated step in battery assembly. Therefore, the last
aim of this thesis was the preparation of a composite positive electrode for highenergy density lithium-ion batteries by the development of one-pot method in
which the NMC622 active material, the P-ETG precursor solution electrolyte, and
carbon additives are mixed and tape-casted onto a current collector. Different
processing procedures were tested in this work, and knowledge on the slurry
recipe and processing parameters was be obtained by studying the effect of the
loading of the active material and solid electrolyte in the composite positive
electrode. One important finding was that the polymerization of the P-ETG
processed in the positive electrode was hindered by the presence of carbon black.
To solve this issue, the UV-initiator was replaced by a thermal-initiator, allowing
to start the polymerization by a heat pulse. However, this thermal polymerization step was responsible for the loss of a part of the MAc in the DES. Applying the insitu synthesis method to fill the pores of the positive electrodes with P-ETG
precursor, made it possible to obtain dense positive electrodes. The performance
was tested in LTO | P-ETG | NMC66 cells, resulting in reasonably high and stable
discharge capacities for 30 cycles. Almost all composition of positive electrodes
synthesized using the one-pot method, mixing the NMC622 active material and PETG electrolyte, result in a high initial discharge capacity compared to the
infiltrated NMC622 electrodes using the in-situ synthesis method described in
chapter 5. This indicates the importance of the processing of the solid electrolyte
inside the electrode. Decreasing the NMC622 active material loading resulted in
the highest discharge capacity. However, increasing the NMC622 active material
loadings resulted in a decreased initial discharge capacity, indicating the
complexity of an electrode preparation process and the importance of the
knowledge on the performance limiting factors. Therefore, additional research on
the processing of on-pot positive electrodes containing the NMC622 active
material and the P-ETG electrolyte is needed to identify the processing limiting
factors and to improve the NMC622 active material loading, discharge capacity
and cycle life of the cell.
2. Impact for battery/solid electrolyte community
Since the publication of the first silica-based eutectogel as a new class of solid
composite electrolytes by Joos and co-workers [1] in 2018, there has been an
increase in research into the use of liquid DES electrolytes as non-flammable,
hybrid solid-state electrolytes for lithium-ion batteries. Especially, the introduction
of the polymer-based eutectogel electrolytes showed a great potential due to their
facile synthesis method and promising properties, such as a high ionic conductivity
at room temperature and relatively broad electrochemical stability window. [2]
Many compositions of DES-containing hybrid electrolytes were described in
literature during the past years. [3]–[8] However, most publications focus only on
the development of a new electrolyte composite and its properties, such as
increasing the ionic conductivity even to higher values. This are indeed very
interesting and needed topics, however, given the availability of many promising
solid electrolytes, the bottleneck of solid-state battery development is no longer
to maximize the ionic conductivity or the anodic stability limit. The main issue has
now shifted towards the integration of the solid electrolyte and the electrode
materials in a battery. This PhD focusses on the combination of the synthesis of
the P-ETG electrolyte and its integration within a porous electrode, which is mostly
overlooked in the existing literature.
A part of the results presented in chapter 3 and 4, resulted in two peer-reviewed
publications, indicating its scientific relevance for the battery field and its possible
contribution to the development of the next generation solid-state batteries.
In summary, the work presented in this PhD thesis provides valuable insights for
the battery and solid electrolyte community for the development of P-ETG as solid
electrolytes, focussing both on their design and their integration into a battery
Low bandgap polymers based on bay-annulated indigo for organic photovoltaics: Enhanced sustainability in material design and solar cell fabrication
No full textAlthough research in the field of organic photovoltaics (OPV) still merely focuses on efficiency, efforts to increase the sustainability of the production process and the materials encompassing the device stack are of equally crucial importance to fulfil the promises of a truly renewable source of energy. In this study, a number of steps in this direction are taken. The photoactive polymers all contain an electron-deficient building block inspired on the natural indigo dye, bay-annulated indigo, combined with electron-rich thiophene and 4H-dithieno[3,2-b: 2',3'-d] pyrrole units. The synthetic protocol (starting from indigo) is optimized and the final materials are thoroughly analyzed. MALDI-TOF mass spectrometry provides detailed information on the structural composition of the polymers. Best solar cell efficiencies are obtained for polymer: fullerene blends spin-coated from a pristine non-halogenated solvent (o-xylene), which is highly recommended to reduce the ecological footprint of OPV and is imperative for large scale production and commercialization. (C) 2017 Elsevier B. V. All rights reserved.This work was supported by the Research Foundation - Flanders (FWO Vlaanderen) (projects G.0415.14N, G.0B67.15N and RADESOL, PhD fellowship M. Van Landeghem). J. Brebels and M. Kelchtermans acknowledge the Agency for Innovation by Science and Technology in Flanders (IWT) for their PhD grants. K.C.C.W.S. Klider acknowledges the Brazilian National Council for Scientific and Technological Development (CNPq) for her Sandwich PhD scholarship. The authors are grateful to B. Van Mele and M. Defour for the thermal analysis, and H. Penxten for the CV measurements
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
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