A rapid photothermal self-healing and high-performance planar microsupercapacitor with a multifunctional MXene-based ionohydrogel electrolyte

Yewon Ku 고려대학교 대학원 2026 국내석사

To ensure the durability of wearable devices, there is a growing demand for materials that can rapidly self-heal even after physical damage. Herein, we report a fully self-healable, high-performance, and flexible microsupercapacitor (MSC) enabled by a novel MXene-based ionohydrogel electrolyte designed for skin-attachable wearable electronics. The ionohydrogel was designed based on the Schiff-base reaction and abundant hydrogen bond for fast self-healing. The Schiff-base reaction occurs between the amide group of acrylamide (AAm) and the aldehyde group of benzene-1,3,5-tricarbaldehyde (BTA), while hydrogen bonding between AAm and acrylic acid also contributes to self-healing. Because the MXene-induced photothermal effect rapidly activates and reforms these dynamic bonds, an ultrafast self-healing ionohydrogel could be synthesized. It achieves self-healing efficiency of 91.0% within 1 minute under 808 nm irradiation. MXene served a dual role in the ionohydrogel, functioning as both an inorganic filler and a photothermal agent. As a filler, MXene increased the ionic conductivity by approximately 60% compared with the MXene-free system. To fabricate a fully self-healable microsupercapacitor, an aniline-trimer-based polyurethane (AT-PU) with photothermal functionality was used as both the substrate and encapsulation layer. AT-PU can completely heal within 3 minutes under the same NIR laser conditions, and by integrating it with the ionohydrogel, an MSC capable of fully self-healing within 3 minutes was achieved. As a result, the MSC restored 100% and 85.7% of its capacitance after the first and fifth healing cycles, respectively. The ionohydrogel was also used as a strain sensor, and body-motion signals were successfully detected using the MSC as the power source. This demonstrates a robust platform for fully self-healable and multifunctional wearable energy storage systems. 웨어러블 디바이스의 내구성을 확보하기 위해서는 물리적 손상 이후에도 빠르게 자가 치유될 수 있는 소재에 대한 수요가 증가하고 있다. 본 연구에서는 피부부착형 웨어러블 전자소자를 위한 새로운 MXene 기반 이오노하이드로겔 전해질을 합성하여, 완전 자가 치유가 가능하며 고성능·유연성을 갖춘 마이크로 슈퍼커패시터(MSC)를 제시한다. 이오노하이드로겔은 빠른 자가 치유를 위해 시프 베이스 반응과 풍부한 수소결합을 기반으로 설계되었다. 시프 베이스 반응은 아크릴아마이드(AAm)의 아마이드기와 벤젠-1,3,5-트라이카바알데하이드(BTA)의 알데하이드기 사이에서 일어나며, AAm과 아크릴산 사이의 수소결합 역시 자가 치유에 기여한다. MXene의 광열효과는 이러한 동적 결합의 활성화 및 재형성을 빠르게 유도하므로, 초고속 자가 치유 이오노하이드로겔의 구현이 가능하였다. 그 결과 808 nm 조사 조건에서 1분 만에 91.0%의 자가 치유 효율을 달성하였다. MXene은 이오노하이드로겔 내에서 광열효과를 내는 물질과 동시에 무기 필러로 사용되었다. MXene이 포함된 전해질은 MXene이 없는 전해질에 비해 약 60%의 이온전도도가 향상되었다. 완전 자가 치유가 가능한 MSC를 제작하기 위해, 광열 기능을 갖는 아닐린 트리머 기반 폴리우레탄(AT-PU)을 기판과 인캡슐레이션 층 (encapsulation layer)으로 사용하였다. AT-PU는 동일한 NIR 레이저 조건에서 3분 이내에 완전히 자가 치유될 수 있으며, 이오노하이드로겔과 통합함으로써 3분 이내에 전체 소자가 완전 자가 치유되는 MSC를 구현하였다. 그 결과 MSC는 첫 번째 자가 치유 후 초기 용량의 100%, 다섯 번째 치유 후에는 85.7%를 회복하였다. 또한 이오노하이드로겔을 스트레인 센서로도 활용할 수 있음을 확인하였으며, MSC 자체를 전원으로 사용하여 신체 움직임 신호를 성공적으로 감지하였다. 이는 완전 자가 치유 기능과 다기능성을 동시에 갖춘 웨어러블 에너지 저장 시스템의 견고한 플랫폼을 제시한다.

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.

Self-healable single-ion conducting polymer electrolytes based on thermo-reversible Diels-Alder reaction

Song, Ju Hwan 고려대학교 KU-KIST융합대학원 2023 국내석사

Single ion conducting solid polymer electrolytes (SPEs) are physically and chemically stable than liquid electrolytes that suppress undesirable side reactions. Restrain of forming byproducts such as Li dendrite can effectively extend the battery life. Additional self-healable and reprocessable functionality is essential for SPEs since the self-healing materials provide industrial and environmental benefits by its sustainability and recyclability. Herein, the ion conducting monomer, 4-styrenesulfonyl (trifluoromethanesulfonyl) imide (LiSTFSI) was copolymerized with two types of cross-linkable monomers, furfuryl methacrylate (FMA) and polyethylene glycol furoyl ester methacrylate (PEGFMA), respectively. Fraction of the conducting unit was varied that 6 types of electrolytes were synthesized. The synthesis of the linear polymers was characterized by NMR and GPC. Their thermal stability up to 400 ℃ was confirmed by TGA. Formation of Diels-Alder cross-linking and its thermos-reversibility was investigated by various technics (DSC, FT-IR, DMA, rheometer). Ion conductivity was recorded 7.07×10-5 S cm-1 at 80 ℃ with high lithium transference number (0.96), attributed to its high electrolyte ratio and presence of PEO oligomer. After extra 30 times of reprocessing, the electrolyte remained its ion conductivity and mechanical properties thus showing good reprocessability of the SPE. 단일 이온 전도 고체 고분자 전해질은 액체 전해질에 비하여 기계적, 화학적으로 안정적이며 전지의 음극에서 생성되는 덴드라이트와 같은 불필요한 생성물의 형성을 효과적으로 억제하고 전지의 수명을 늘리는 효과적인 수단이 될 수 있다. 고분자 전해질에 자가 치유 기능성을 도입하는 것은 고체 재료의 재생성과 지속성에 기여할 수 있기 때문에 환경적, 산업적으로 중요하다. 본 연구에서는 이온 전도 단량체인 LiSTFSI를 두 가지 자가 치유 기능성 단량체인 FMA, PEGFMA와 각각 공중합하였다. 또한 LiSTFSI의 첨가 비율을 달리하여 총 여섯 가지의 단일 이온 전도 고체 고분자 전해질을 합성하였다. 선형 고분자의 합성은 NMR, GPC를 통해 확인하였으며, TGA를 통해 고분자 종류에 따라 400 ℃까지의 열적 안정성을 확인하였다. 또한 DSC, FT-IR, DMA, 레오미터를 통해 가교 결합의 형성과 그 가역성을 확인하였다. 이온 전도도는 80 ℃에서 7.07×10-5 S cm-1까지 측정되었고 0.96의 높은 리튬 전도율을 보였으며, 이온 전도 단량체의 비율 및 PEO 사슬의 도입 여부에 따라 긍정적인 영향을 받는 것으로 나타났다. 추가적인 30회의 재처리 과정 이후 이온 전도도와 기계적 물성에서 높은 재현성을 보여 고분자 전해질의 높은 재생 기능성을 확인할 수 있었다.

Design of Dynamic Covalent Gel Polymer Electrolytes for Reprocessable Lithium Metal Batteries

전용하 인하대학교 대학원 2026 국내석사

The development of energy storage devices has led to a proportional increase in the generation of end-of-life batteries. Consequently, the amount of discarded electrolytes and lithium salts is also rising, necessitating the establishment of effective recovery and reuse strategies. In particular, polymer electrolytes based on permanent covalent bonds face limitations in terms of reprocessability and recyclability. To overcome these challenges, this study introduces dynamic covalent polymer electrolyte systems, designed using Diels–Alder reactions. The Diels–Alder-based polymer electrolyte was designed by introducing crosslinking points through covalent bonding between furan and maleimide groups. The optimized polymer electrolyte (CAE62) exhibited a high ionic conductivity of 1.4 × 10−3 S/cm at room temperature and excellent mechanical robustness with a shear modulus of 1.1 × 105 Pa. Moreover, due to its thermally reversible characteristics, the CAE62 electrolyte demonstrated self-healing behavior via retro-Diels–Alder reactions at 80°C, effectively restoring its structure after damage. In addition, the polymer matrix was simultaneously employed as a cathode binder to fabricate composite electrodes. By enabling interfacial self-healing between the composite electrode and the polymer electrolyte, the system achieved enhanced interfacial stability, and a higher specific capacity compared to conventional cathodes. 증가하는 에너지 저장 장치들의 사용량에 따라 폐배터리의 발생량도 비례하여 증가하고 있다. 이에 따라, 폐배터리 내 전해질 및 리튬 염의 폐기량 역시 늘어나고 있기 때문에 폐배터리 자원의 재사용 및 회수에 대한 개발이 필요하다. 특히, 영구 공유 결합 기반의 고분자 전해질은 재가공 및 재사용에 한계를 가지고 있기 때문에 본 연구에서는 Diels-Alder 반응을 이용한 동적 공유 결합 기반의 고분자 전해질 시스템을 준비했다. Diels-Alder 기반의 고분자 전해질은 Furan 과 Maleimide 의 공유 결합을 통해 가교점을 형성하여 설계했다. 최적화된 고분자 전해질(CAE62)은 상온에서 높은 이온 전도도(1.4 × 10-3 S/cm)와 우수한 기계적 견고성(1.1 × 105 Pa)을 보여주었고, 열적 가역 특성을 가진 CAE62 전해질은 80 °C 에서 역반응을 통해 손상된 전해질의 자가 치유 특성을 보였다. 또한, 고분자 매트릭스를 양극의 바인더로써 동시 사용하여 복합 전극을 제작했으며, 복합 전극과 고분자 전해질 계면 사이에서 자가 치유를 유도하여 향상된 계면 안정성과 기존 양극 대비 높은 단위 무게당 용량을 가졌다.