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- 검색키워드
- 주제어 : Donor Number (검색결과 4 건)
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Poly(3,4-ethylenedioxythiophene)의 전기화학적 합성 및 물성연구
PEDOT [Poly(3,4-ethylenedioxythiophene)]을 여러 다른 전해질음이온[tetra-n-butylammonium hexafluorophosphate(pF_6), tetra-n-butylammonium per chlorate(NCIO₄), tetra-n-butylammonium(tetrafluoroborate)(BF₄), lithium per chlorate(LiCIO₄)]을 사용하여 전기화학적 방법으로 합성하였다. 또한 고분자사슬과 전해질용액간의 상호작용을 알아보기 위해 donor number(DN)가 다른 propylene carbonate(DN : 15.1), acetonitrile(DN : 14.1), benzo nitrile(DN : 11.9), nitrobezene(DN : 4.4), nitromethane(DN : 2.7)을 전해질용매로 사용하여 PEDOT 필름을 합성하고, 전기화학적 합성에 미치는 중합전위, 중합온도, H₂O의 영향을 조사하였다. PF_6^-을 전해질 음이온으로 하여 합성할 경우 NCIO₄^-, BF₄^-, LiCIO₄^-를 사용한 경우보다 전기전도도가 높게 나타났다. 이는 음이온의 크기가 클수록 고분자 사슬간의 공간을 넓혀주어 전하의 이동을 용이하게 하기 때문이다. 또한 donor number가 커질수록 단량체의 라디칼양이온과 전해질 용매간의 상호작용이 증가하여 라디칼양이온이 안정화되며, 결함이 적은 공액구조가 긴 고분자가 합성되어 전도도가 높게 나타났다. 저온에서 합성된 시료의 경우 전기전도도의 상승이 나타났으며 이는 중합속도 저하에 따른 분자량의 증가에 기인한다. 중합전위가 높아질수록 전기전도도는 상승하지만 열적안정성은 감소함을 TGA 분석을 통하여 확인하였다. 합성된 시료의 전기전도도의 온도의존성 측정결과 모두 ID-VRH model에 잘 부합됨을 확인하였다. PEDOT [poly(3,4-ethylenedioxythiophene)] films were synthesized electrochemically using PF_6^-, NClO₄, BF₄^-, LiClO₄^- as electrolyte anions. To investigate the interaction between the polymer chain and electrolyte solution electrolyte solutions with different donor number (DN) [propylene carbonate (DN : 15.1), acetonitrile (DN : 14.1), benzonitrile (DN : 11.9), nitrobezene (DN : 4.4), nitromethane (DN : 2.7)] were used to synthesize PEDOT films and the effects of applied potential, polymerization temperature, addition of H₂O to electrolyte on the characteristics of PEDOT films were studied. PEDOT film doped with PF_6^- electrolyte anion showed higher electrical conductivity than those doped with NClO₄^-, BF₄^-, LiClO₄^- electrolyte anions. This was explained with the increase in charge carrier mobility which was attribute to the increase in interchain distance due to the bulky size of electrolyte anion. As the donor number of electrolyte solvent increased, the electrical conductivity of PEDOT film increased. This was explained by the increase in conjugation length of polymer which was a result of stabilization of radical cation due to the improvement of interaction between radical cation and solvent. PEDOT films synthesized at 0℃ showed higher conductivity than that synthesized at room temperature which could be explained with the increase in molecular weight. As the applied potential in electrical synthesis increased, the electrical conductivity of PEDOT films increases, however, thermal stability of the films decreased. 1D-VRH model provided best fit to the data of temperature dependence of electrical conductivity of PEDOT films synthesized in this study
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Ionic Liquid-based Gel Polymer Electrolytes For Lithium-ion Batteries
KULKARNI UDDHAV 성균관대학교 일반대학원 2025 국내박사
In the last three decades, lithium-ion batteries (LIBs) have received much attention due to their properties such as light weight, high energy density, high ionic conductivity, and negligible memory effect. LIBs could be a promising candidate for energy storage in the face of green alternatives to fossil fuels. Their commercialized version consists of a graphite anode, liquid electrolyte, a cathode made up of metal oxides and a separator. These liquid electrolytes play a vital role in LIBs and ionic conductivity of 10-2 S cm-1 can be achieved. Traditional liquid electrolytes (LEs) pose safety risks due to their flammability and volatility. Ionic liquids (ILs) offer a safer alternative, boasting inherent properties such as non-flammability, thermal stability, and high electrochemical stability, making them ideal for lithium-ion battery applications. The polymeric form of ILs, poly(ionic liquids) (PILs), is a new class of polymer electrolytes which combine the properties of ILs and polymer. However, differently from conventional solid polymer electrolytes (SPEs), in the case of PILs no additional salt needs to be added to the SPE since the pendant counter-ions are free to move and responsible for the ionic conductivity. PILs offers high thermal and electrochemical stability in addition to mechanical stability. Moreover, PILs with bulky anions like bis(trifluoromethanesulfonyl)imide (TFSI) show self-healing properties benefiting the development of flexible polymer electrolytes for wearable electronics. Despite the beneficial properties, use of PILs as battery electrolyte has been hampered due to their low ionic conductivities at room temperature. To address this issue various strategies have been implemented including co-polymerization, addition of plasticizers (like LE, inorganic nanoparticles, ILs, etc.) which has led to enhanced conductivities and exceptional cycling performance. In the first chapter of this thesis, quantitative analysis of factors affecting the physicochemical behavior of ILs in electrolyte solution has been studied. Since solvents or ILs interact with dissociated ions, it is crucial to understand the factors that influence the solvent-solute relationship. Therefore, the ionic interactions are measured by nuclear magnetic resonance (NMR) spectroscopy and quantitively expressed in terms of donor number (DN). DN of ILs offering valuable insights for developing safer and more efficient electrolytes for lithium-ion batteries (LIBs) with enhanced charge-carrying capacity. In the second chapter, crosslinked network polymer of poly(acrylonitrile-r-vinylidene diazide) with tethered tetrazolium rings (xPAN+) as highly stable and ion-selective gel polymer electrolytes (GPEs) for lithium metal batteries. The cationic rings play a crucial role in facilitating the movement of Li ions by interacting with both anions and solvent molecules, resulting in a remarkable transference number and ionic conductivity. Furthermore, the half-cell exhibited excellent capacity retention. In the third chapter, polymer coated silica nanoparticles-based imine vitrimers (P@SNP-PHT) used as polymer electrolytes (PE). These electrolytes show self-healing ability at room temperature without any external stimuli. Moreover, the introduction of P@SNP in polymer matrix increases both stress and strain values of P@SNP-PHT films. P@SNP-PHT films shows high ionic conductivity and moderate lithium transference number with excellent electrochemical stability. The research investigates the fundamental properties of ionic liquids and their interactions with Li salts, aiming to develop novel ionic-polymer electrolyte systems with enhanced lithium transference numbers and self-healing capabilities.
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