https://scholar.dgist.ac.kr/handle/20.500.11750/237 Sat, 03 Oct 2026 23:10:24 GMT 2026-10-03T23:10:24Z https://scholar.dgist.ac.kr/handle/20.500.11750/60903 Title: Dendrite-free Zn deposition enabled by a TFSI-Nafion modified carbon felt electrode for zinc bromine flowless batteries Author(s): Jung, Jaehee; Shanmugam, Sangaraju Abstract: Aqueous zinc-bromine flowless batteries (ZBFLBs) are emerging as promising next-generation energy storage systems owing to their low-cost active materials, simplified cell configuration, intrinsic safety, and high energy densities. However, zinc dendrite formation on the anode remains a critical challenge that limits cycling stability and operational lifetime in aqueous zinc-based batteries. During repeated cycling, nonuniform Zn2+ nucleation and growth induce surface short circuits and dead zinc formation, collectively leading to capacity fading and cell failure. Herein, a TFSI-Nafion composite coating strategy is proposed to enhance Zn2+ transport kinetics and promote uniform zinc plating/stripping. The modified electrode enables homogeneous zinc deposition, thereby extending the ZBFLB lifespan. At a depth of charge of 96.5 mAh, the electrode maintains an average coulombic efficiency of 96.52% with uniform zinc deposition morphology. Furthermore, a practical ZBFLB demonstrates stable operation at a high depth of charge of 386 mAh for 800 h with a coulombic efficiency of 78.08%. This work provides an effective electrode design strategy to promote uniform Zn deposition and extend the cycle life of ZBFLBs. Mon, 31 Aug 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60903 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60543 Title: Efficient Electrochemical NO Reduction at Low Overpotential via Synergistic RuCu Alloy Nanoparticles Author(s): Jang, Seoyoung; Joo, Yong Lak; Shanmugam, Sangaraju Abstract: Ammonia (NH3) synthesis via electrochemical nitric oxide reduction (NORR) has emerged as a promising alternative to the Haber-Bosch process, which requires high temperatures and pressures. However, NORR still faces critical challenges, including side reactions, limited mass transfer, and high overpotential requirements. Transition metals have been widely employed to address these issues owing to their favorable NO adsorption properties; however, they suffer from intermediate overbinding and require high overpotentials to achieve meaningful catalytic activity. To overcome these limitations, we introduce a noble-metal alloying strategy that combines the high electron-transfer kinetics of noble metals with the tunable NO adsorption properties of transition metals, thereby synergistically enhancing catalytic activity for selective NH3 production. We designed Ru-Cu alloy nanoparticles supported on nitrogen-doped carbon nanorods (Ru x Cu100-x @NCNR), and the optimized Ru5Cu95@NCNR catalyst exhibited an ammonia yield of 32.66 +/- 4.38 mu mol cm-2 h-1 and a Faradaic efficiency of 94 +/- 1.25% (FENH3) at -0.2 V vs RHE, notably lower overpotential than that reported for conventional NORR catalysts, demonstrating energy-efficient ammonia production. Long-term stability tests confirmed the sustained catalytic performance, and its practical applicability was further validated through integration into a Zn-NO battery system, highlighting its potential for next-generation energy conversion devices. Mechanistic investigations revealed that precise control of Ru content induces structural modulation of the RuCu alloy, thereby regulating the strength of NO adsorption and facilitating efficient protonation, ultimately governing high NH3 selectivity. Sun, 31 May 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60543 2026-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60539 Title: Stabilizing Highly Sulfonated Poly(ether ether ketone) Membranes with Polybenzimidazole for Zinc-Bromine Redox Flow Batteries Author(s): Jannah, Sifathul; Kim, Minji; Shanmugam, Sangaraju Abstract: Zinc-bromine redox flow batteries (ZBRFBs) suffer from membrane degradation under bromine-rich operating conditions. Highly sulfonated poly(ether ether ketone) (SPEEK) at DS approximate to 75-79% offers superior ionic conductivity but undergoes excessive swelling and mechanical failure in ZBRFB electrolytes. Here, we report the first systematic application of Na+-pretreated SPEEK/polybenzimidazole (PBI) blend membranes to ZBRFBs, where Na+-ion exchange pretreatment enables homogeneous blending of these otherwise incompatible polymers. The optimized SPEEK/PBI 2.5 wt % membrane achieves a 3-fold reduction in Br-2 permeability and improves energy efficiency from 83.6% to 88.4%, retaining 94.22% discharge capacity after 280 cycles versus 54% at failure for pristine SPEEK at cycle 85. Postmortem analysis confirms reduced desulfonation and improved morphological integrity, consistent with the acid-base network reinforcement by PBI. These results demonstrate that controlled PBI blending effectively extends the usable DS range of SPEEK in harsh bromine-containing electrolytes. Thu, 30 Apr 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60539 2026-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60000 Title: Cationic Covalent Organic Framework-Based Membranes for High-Performance Zn/Br2 Redox Flow Batteries Author(s): Han, Dabin; Abuawwad, Lamia; Kim, Minji; Schneemann, Andreas; Shanmugam, Sangaraju Abstract: Zn/Br2 redox flow batteries (Zn/Br2 RFBs) have attracted significant attention for large-scale energy storage applications due to their high safety and efficiency. The membrane is a critical component of Zn/Br2 RFBs, directly influencing their efficiency and power density. However, designing suitable membranes is challenging due to an intrinsic trade-off between achieving fast bi-ionic species transport (Zn2+ and Br−). Increasing anion transport pathways improves Br− conductivity but simultaneously accelerates Brn− shuttling and self-discharge, while strong Brn− blocking typically restricts anion mobility and causes ionic imbalance. To address this trade-off, a membrane design strategy is proposed that enhances anion conduction while simultaneously suppressing Brn− migration by incorporating a cationic COF construced from ethidium bromide and triformylphloroglucinol (EB-COF) into a Nafion (NF) matrix. The EB-COF exhibits -CHO and -NH2 functional groups on its surface. The interaction between water molecules and these functional groups forms continuous, abundant water networks within the composite membrane, significantly enhancing its ion conductivity. In addition, the abundant quaternary amine groups (N+) of the EB-COF significantly reduce the polybromide (Brn−) shuttle by absorbing Br2 while forming Brn−. In particular, NF/EB-COF(0.3), in which 0.3 wt.% EB-COF is introduced into the NF polymer matrix, exhibits the most effective characteristics and has excellent performance for Zn/Br2 RFBs. Consequently, the Zn/Br2 RFBs assembled with the NF/EB-COF composite membrane demonstrate outstanding performance, achieving an energy efficiency of 89.1% at a current density of 40 mA cm−2. Sat, 31 Jan 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60000 2026-01-31T15:00:00Z