Organic Chemistry, Renewable Energy, Sustainability and the Environment, Materials Chemistry, Electrochemistry
10
Scopus Publications
Scopus Publications
Oxidized λ-Carrageenan as an Aqueous Silicon-Anode Polymer Binder with Reduced Viscosity for Lithium-Ion Batteries Sang Wook Kim, Rajeev K.K, Yumi Kang, Jong Hyeok Han, Seo Jin Yeon, Senthil Kannan, Tae-Hyun Kim ACS Sustainable Chemistry and Engineering, 2024 λ-Carrageenan (L-CGN) exhibits high potential as a Si-anode binder due to its high adhesive strength and 3D structure with Si. This study aimed to improve the mechanical properties and reduce the high viscosity of polysaccharides, including L-CGN, by oxidation. The aldehyde functional group introduced via oxidation served as a hinge, providing flexibility to relatively stiff polysaccharide binders and strengthening their interactions with the Si active materials. The oxidized CGN binders exhibited enhanced adhesion and mechanical strength, thereby maintaining the electrode integrity against Si’s volume expansion. The Si@Ox-L-CGN electrode, combining oxidized L-CGN (Ox-L-CGN) as a binder and 350 nm-sized Si as an active material, displayed enhanced mechanical properties compared to those of the Si@L-CGN electrode. Si@Ox-L-CGN-5, oxidized by 5% relative to Si@L-CGN, showed an improved initial Coulombic efficiency of 78.6% compared to that of Si@L-CGN (72.6%). Furthermore, at a Si loading level of 1.0 mg cm –2, Si@Ox-L-CGN-5 displayed a capacity of 2032 mAh g –1 after 100 cycles (compared to a very low value of 248 mAh g –1 for Si@L-CGN) and a high capacity retention of 73.9%. The results highlight the potential of Ox-L-CGN as a binder for Si anodes with a large particle size and a high loading level.
Lambda Carrageenan as a Water-Soluble Binder for Silicon Anodes in Lithium-Ion Batteries Wonseok Jang, Rajeev K. K., Gaurav M. Thorat, Sangwook Kim, Yumi Kang, Tae-Hyun Kim ACS Sustainable Chemistry and Engineering, 2022 The large volume expansion of a silicon (Si) anode causes severe mechanical failure, limiting its use in lithium-ion batteries (LIBs). Using functional polymers as a binder material is an approach to this issue. We explore the applicability of the water-soluble natural polysaccharide lambda carrageenan (CGN) as a binder for Si nanoparticles in LIBs. The characteristic binder properties of commercial (CGN-com) and custom (ext-CGN) CGNs are investigated. CGN binders exhibit excellent mechanical characteristics, remarkable interfacial adhesion, and strong cohesion. The high density of sulfonyl groups in CGN improves the lithium-ion transport kinetics; CGN effectively buffers the volume expansion of Si during alloying, enhancing cycling and rate performance. After 300 cycles at 0.5 C, the Si@CGN electrode delivers a reversible capacity of 1623.75 mAh g–1 and a rate capability of 2143.72 mAh g–1 at 5 C. The electrochemical performance of Si@CGN-ext is about 91% of that of Si@CGN-com. Under all test conditions, both outperformed Si anodes made with traditional binders. When paired with the commercial NCM811 cathode, full cells using Si@CGN-com and Si@CGN-ext have capacities of 79.96 and 75.68 mAh g–1, respectively, and superior stability for 50 cycles. This study reveals the potential of CGN as a low-cost, sustainable binder for Si anodes.
Chitosan- grafted-Gallic Acid as a Nature-Inspired Multifunctional Binder for High-Performance Silicon Anodes in Lithium-Ion Batteries Rajeev K. K., Wonseok Jang, Sangwook Kim, Tae-Hyun Kim ACS Applied Energy Materials, 2022 Due to its high theoretical specific capacity and natural abundance, silicon (Si) and its composites are considered to be pivotal anode materials for high-energy-density next-generation lithium-ion batteries (LIBs). However, the significant volume changes during the repeated lithiation/delithiation process cause the loss of electrical contact and the continuous formation of a solid electrolyte interface (SEI), hindering Si’s practical applications. The rational design of the polymer binder is an efficient approach to preserve the electrode’s structure from large Si volume changes, thereby enhancing the cycle performance in lithium-ion batteries. We developed an aqueous binder using a plant-inspired adhesive phenolic moiety, gallic acid (3,4,5-trihydroxybenzoic acid, GA), grafted onto the marine-based polymer, chitosan (CS) by a simple radical reaction. The chitosan-grafted-gallic acid, CS-g-GA, not only improves the water solubility of CS but also achieves enhanced binding properties onto Si, hence contributing to better accommodating the volume expansion of Si during the repeated cycling and also maintaining the structural integrity of the Si electrode electronic made from the CS-g-GA as a binder. Si@CS-GA-100 exhibits excellent high-rate capability and long cycling stability, delivering a high reversible specific capacity of 1868 mAh g–1 with a capacity retention of 67% at a rate of 0.5 C after 350 cycles.
A conductive self healing polymeric binder using hydrogen bonding for Si anodes in lithium ion batteries Jaebin Nam, Eunsoo Kim, Rajeev K.K., Yeonho Kim, Tae-Hyun Kim Scientific Reports, 2020 A ureido-pyrimidinone (UPy)-functionalized poly(acrylic acid) grafted with poly(ethylene glycol)(PEG), designated PAU-g-PEG, was developed as a high performance polymer binder for Si anodes in lithium-ion batteries. By introducing both a ureido-pyrimidinone (UPy) unit, which is capable of self-healing through dynamic hydrogen bonding within molecules as well as with Si, and an ion-conducting PEG onto the side chain of the poly(acrylic acid), this water-based self-healable and conductive polymer binder can effectively accommodate the volume changes of Si, while maintaining electronic integrity, in an electrode during repeated charge/discharge cycles. The Si@PAU-g-PEG electrode retained a high capacity of 1,450.2 mAh g−1 and a Coulombic efficiency of 99.4% even after 350 cycles under a C-rate of 0.5 C. Under a high C-rate of 3 C, an outstanding capacity of 2,500 mAh g−1 was also achieved, thus demonstrating its potential for improving the electrochemical performance of Si anodes.
