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Yayın Colloidal polypyrrole as binder for silicon anode in lithium ion batteries(Energy Storage, 2022) Yayla, Işık İpek Avcı; Yuca, Neslihan; Sezer, Esma; Ustamehmetoğlu, BelkısSilicon (Si)-based anodes have limited application in lithium ion batteries (LIBs) due to the loss of contact with current collector because of large volume change during lithiation and delithiation processes. In this study, pyrrole (Py) was polymerized chemically by cerium ammonium nitrate (CAN) and conductive colloidal polypyrrole (Col-PPy) was obtained in one step in N,N0 - dimethylformamide (DMF). To overcome problems during the volume change, Col-PPy was then used as polymeric binder with Si nanoparticle (SiNP) in Sianode and it called as “Col-PPy/SiNP.” In order to improve the cyclability and capacity of Si-anodes, Col-PPy solution was used also together with polyvinylidenefluoride (PVDF) and polyvinylpyrrolidone (PVP). These Si-anodes were further analyzed with cycle tests and combined cycle tests at different rates (C-rate) in half cells and scanning electron microscopy images of electrodes were taken before and after cycling. All results suggested that as an anode for LIB, Col-PPy/SiNP exhibited high reversible capacity (2617 mAh/g at C/10 [0.42 A/g]) and good cycling performance (reversible capacity of 1400 mAh/g after 189 cycles at C/3 [1.4 A/g]).Yayın Determination of Si/graphite anode composition for new generation Li-ion batteries: a case study(Tubitak Scientific & Technological Research Council Turkey, 2022) Kalafat, İlknur; Yuca, NeslihanSilicon with the properties of high capacity capability, moderate working potential, environmental sensitivity, and existence are the highly promising anode materials for lithium-ion batteries. Silicon anodes have disadvantageous properties and advantages like 300% volume change during lithium insertion and extraction process that can result in capacity fading and a shorter lifetime of the battery. In the literature, different optimizations of Silicon with different nanomaterials or composite materials, in different ratios, and with different binders and different procedures have been studied. The physical mixing of silicon with carbon provides a good performance by combining the high lithium storage capacity of the silicon and the good mechanical and conductive properties of carbon. Binders are one of the other factors affecting the performance of the Si/C anodes. In this study, different ratios of silicon/graphite combinations were tested. The Si/C hybrid material provides an advantageous and efficient use for innovative lithium-ion anodes and available lithium-ion battery technology when the Si/C match performs a suitable combination of two material properties, such as the high lithium storage capacity of silicon and the conductive properties of carbon. This study is aimed to improve the performance of the cell by changing the amount of active material and polymer in the electrode by finding the most appropriate amount of active substance and binder polymer ratio in the electrode. The electrochemical result of the composition, which compensates for the problems caused by the volume expansion of the silicon by using less silicon, showed higher capacitive properties, as it exhibits better adhesion among these compositions with a higher binder ratio. This study resulted in more than 1000 mAh/g specific capacity after 100 cycles at C/3 rate and structural characterization of the samples before and after cycling provided information about the electrode content.Yayın Effect of Mn, Ni, Co transition metal ratios in lithium rich metal oxide cathodes on lithium ion battery performance(Elsevier, 2020) Çetin, Büşra; Camtakan, Zeyneb; Yuca, NeslihanLithium rich layered metal oxide is a high energy density cathode material for new generation lithium ion batteries (LIBs). This material has Li [Li1/3Mn2/3]O-2 and LiMO2 (M: Ni, Co, Mn, Al etc.) structure and exhibit higher irreversible capacity and cycle life than conventional cathode materials. In this study, the stoichiometry of metals in the lithium rich cathode material formulation was investigated by changing Mn, Ni and Co ratios. Li1.2Mn0.49+xCo0.2-2xNi0.2-2xAl0.02O2 (x = 0, 0.01, 0.02, 0.03). formulation was used and the prepared lithium rich cathode active powders were structurally characterized by XRD, ICP and NAA. Li-rich cathodes were tested by electrochemical methods, too. (c) 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the E-MRS Fall Meeting, 2019. All rights reserved.Yayın The electrochemical behavior of silicon and graphite anode materials with different cathodes for lithium ion cells(Elsevier, 2020) Yuca, NeslihanNew material compositions with new electrode designs have the serious potential to improve the energy per weight and volume at reduced cost for lithium ion batteries. Herein, the advantage and disadvantage of electrode materials for LIBs were investigated in both half and full cells. It was found high capacity materials like silicon anode and Li-rich cathode provide higher specific capacity in mAh/g. In full cell configuration Graphite/Li-rich cathode had 92mAh/g specific capacity after 100 cycles at C/2.Yayın Influence of Doping and Controlled Sn Charge State on the Properties and Performance of SnO2 Nanoparticles as Anodes in Li-Ion Batteries(American Chemical Society, 2020) Vazquez-Lopez, Antonio; Maestre, David; Ramirez-Castellanos, Julio; Gonzalez-Calbet, Jose M; Pis, Igor; Nappini, Silvia; Yuca, Neslihan; Cremades, AnaLi-ion batteries (LiB) play nowadays a major role in several technological fields. In addition to enhanced high capacity and long cyclability, some other issues regarding safety, materials sustainability, and low cost remain unsolved. Tin oxide (SnO2) presents several of those advantages as an anode material; however, some aspects still require to be investigated such as capacity fading over cycles. Herein, tin oxide nanoparticle-based anodes have been tested, showing high capacities and a significant cyclability over more than 150 cycles. A complementary strategy introducing doping elements such as Li and Ni during the synthesis by hydrolysis has been also evaluated versus the use of undoped materials, in order to assess the dependence on SnO2 quality and properties of battery performance. Diverse aspects such as the Sn charge state in the synthesized nanoparticles, the variable incorporation of dopants, and the structure of defects have been considered in the understanding of the obtained capacity.Yayın Interconnected conductive gel binder for high capacity silicon anode for Li-ion batteries(Elsevier, 2020) Taşkın, Ömer Suat; Yuca, Neslihan; Papavasiliou, Joan; Avgouropoulos, GeorgeA new design for conjugation and crosslinking combined with a conjugated polymer and its application for high capacity Li-ion battery are demonstrated. Polyfluorene (PF), poly(phenylene) (PP), with lateral substituents, namely carboxylic acids, as a potential building block for conjugation was synthesized and characterized. The synthesis was achieved through Suzuki polycondensation reaction in the presence of Pd(PPh3)4 catalyst by using dibromo benzoic acid in conjunction with dioctylfluorene-diboronic acid bis(1,3-propanediol) ester. Thermal chemical cross-linking between carboxylic acid in the polymer backbone and free hydroxyl groups in poly(vinyl alcohol) (PVA) has been performed in the presence of Si. This approach enables a polymer binder with multi-functionality providing a high electronic conductivity and good cycling stability. Overall, we report on a Si-anode with capacity of 1932 mAh/g at C/3, demonstrating the improvement of the electrode using gel polymer binder.Yayın Novel approach with polyfluorene/polydisulfide copolymer binder for high-capacity silicon anode in lithium-ion batteries(Wiley, 2020) Bulut, Emrah; Güzel, Emre; Yuca, Neslihan; Taşkın, Omer S.In this study, as a novel design with the collaboration of a fluorene and sulfide-based copolymer for Li-ion battery application is presented. Polyfluorene-co-polydisulfide is prepared with desired functional groups to yield a conductivity and good adhesion. These critical and important features are performed by preparing polymers with proper functional groups. The preparation process is accomplished via Suzuki coupling process under Pd catalyst by combining separately synthesized 4,4 '-dibromodiphenyl disulfide in combination with 9,9-dioctylfluorene-2,7-bis(trimethylborate). The fully obtained capacity of the silicon particles, that is, at C/10 with the capacity of 1250 mAh g(-1) after the 500th cycle, approves the good performance by preserving capacity stability till 600th cycles. The designed and synthesized polymer binder with different functionalities and carbon nanotube additive show better characteristics such as conductivity, high polarity, and binding adhesion. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48303.Yayın An overview on efforts to enhance the Si electrode stability for lithium ion batteries(Wiley, 2020) Yuca, Neslihan; Taşkın, Omer S.; Arici, ElifThis report summarizes the challenges and developments related to the cycle stability of Si anodes. It describes the two-component material concepts using polymer blends and the approaches to material optimization for more stable Si anodes. Since the anode behavior also depends strongly on the Si particle size (and in polymer mixtures no uniform Si particle size is given), the properties of the Si anodes depending on the Si particle size and the underlying fundamental processes at the solid-electrolyte interface were described shortly. Bicomponent silicon-based composites (carbon additives, inorganic nanoparticles and polymers) on the anode behavior were compared by two properties: specific capacity and cycle number of the anodes. This article focuses on Si-polymer blends where the polymer can act as a binder or/and as a solid-state electrolyte. To help further the understanding the role of polymer we have gathered together useful data from the literature on solubilities, flexibility and hardness for the polymers generally used. We offer a perspective for polymer hydrogels that will enable a promising material composition for stable Si anodes.Yayın Self-healing systems in silicon anodes for li-lon batteries(Materials, 2022) Yuca, Neslihan; Kalafat, İlknur; Güney, Emre; Çetin, Büşra; Taşkın, Ömer S.Self-healing is the capability of materials to repair themselves after the damage has occurred, usually through the interaction between molecules or chains. Physical and chemical processes are applied for the preparation of self-healing systems. There are different approaches for these systems, such as heterogeneous systems, shape memory effects, hydrogen bonding or covalent–bond interaction, diffusion, and flow dynamics. Self-healing mechanisms can occur in particular through heat and light exposure or through reconnection without a direct effect. The applications of these systems display an increasing trend in both the R&D and industry sectors. Moreover, self-healing systems and their energy storage applications are currently gaining great importance. This review aims to provide general information on recent developments in self-healing materials and their battery applications given the critical importance of self-healing systems for lithium-ion batteries (LIBs). In the first part of the review, an introduction about self-healing mechanisms and design strategies for self-healing materials is given. Then, selected important healing materials in the literature for the anodes of LIBs are mentioned in the second part. The results and future perspectives are stated in the conclusion section.Yayın Synergistic effect of carbon nanomaterials on a cost-effective coral-like Si/rGO composite for lithium ion battery application(PERGAMON-ELSEVIER SCIENCE LTD, 2020) Benzait, Zineb; Yuca, NeslihanThe emergence and the continuous rise of smart technologies require to emergently meet their ever-increasing energy demand. Improving the commercial lithium-ion batteries (LIB) by using silicon-which has a distinct energy storage capacity-might be a promising solution. However, solving Sirelated problems, such as gross volume variation and low electrical conduction, is indispensable. Preparing different Si nanostructures having certain internal voids, and adding some conductive materials, are two smart approaches largely used to mitigate the volume expansion and to enhance the electrons transport of LIB anodes. Still, their raw materials and their preparation methods are generally costly, which limits their feasibility for commercial scalability. In this study, we synthesized a coral-like nanoporous Si/rGO composite, starting from cheap raw materials (graphite and Al-Si powders), and using simple methods which do not need any high temperatures or sophisticated equipment. The preparation steps were also reduced, as the reactions of Al-etching and GO reduction concurrently occurred. The LIB half-cells made on this composite were further improved by incorporating other carbon nanomaterials which had a synergistic effect on both cycling and rate performances: a reversible capacity of 1080 mAh g(-1) at 0.2 A g(-1) after 250 cycles; and similar to 1710,1300,1030 - and 840 mAh g(-1) at a rate of 1, 2, 3, and 4 A g(-1) respectively, have been achieved. Testing a full battery with an LCO cathode has also given a promising result: a reversible capacity of similar to 54 mAh g(-1) at 36 mA g(-1) after 25 cycles has been obtained. (C) 2020 Elsevier Ltd. All rights reserved.Yayın Synthesis and characterization of li-rich cathode material for lithium ion batteries(Elsevier, 2020) Cetin, Busra; Camtakan, Zeyneb; Yuca, NeslihanLithium rich (Li-rich) transition metal oxide cathodes are considered to be among the most promising intercalation cathode materials used for lithium-ion batteries (LIBs) with their high energy density above 900?Wh/kg. Li1.252Mn0.557Ni0.123Co0.126Al0.0142O2 layered Li-rich nickel manganese cobalt (NMC) cathode material was synthesized by sol-gel method. This study aims to reveal the superiority of Li-rich cathode material over existing commercial cathodes. The stoichiometric ratio of Li-rich cathode material was confirmed by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), portable X-ray Fluorescence (pXRF) and Instrumented Neutron Activation Analysis (INAA). Structural and morphological characterization of Li-rich NMC material was examined with X-ray diffraction (XRD) and Scanning Electron Microscopy-Emission with Energy Dispersive Spectroscopy (SEM-EDS). Electrochemical performances of Li-rich NMC and commercial NMC111 cathode materials in coin cell at C/10, C/5 and 1C were investigated. The discharge capacity of Li-rich NMC and NMC111 was found to be 160, 156, 96 mAhg?1 and 153, 120, 72 mAhg?1 at C/10, C/5, 1C, respectively.Yayın Systematic structural characterization of high-density porous silicon anodes in lithium-ion batteries(Wiley, 2019) Yuca, Neslihan; Colak, Uner; Liu, GaoLithium-ion batteries lead to high energy density, especially desired for portable electronic device applications. Advanced electrode structures for high energy density lithium-ion batteries make the technological breakthrough by improving performance. In the focus of this study, a simple, low cost, scalable, and a versatile way is chosen to obtain high-density SiO-based electrodes with high porosity for lithium-ion batteries. SiO anode is fabricated in a conventional doctor blade system with the addition and removal of the NaCl to get a desired porous anode structure. Porosity and porous structure were characterized by various techniques such as atomic force microscopy, scanning electron microscope, mercury porosimetry, and pycnometry. The results showed that the porosities can be formed successfully after salt addition and removal method by providing the values of pore volumes and porosities of the electrodes before and after the salt-washing process. According to NaCl salt content, the level of porosities was changed and it affected the electrochemical cycling performance of the lithium-ion cells.
