Fluorescence-Enabled Self-Reporting for Redox Flow Batteries

Abstract

Monitoring battery health is challenging. Self-reporting enables the rapid health assessment of redox flow batteries (RFBs) and provides insight into degradation mechanisms of electrochemically active molecules (redoxmers). Here we introduce fluorescence as an orthogonal property to probe this chemistry in situ. An established anolyte redoxmer, 2,1,3-benzothiadiazole, is rendered an efficient blue-green fluorophore through minimalistic derivatization. One of the derivatives is electrochemically reversible with a long lifetime and cycling stability in the charged state. Spectroscopic measurements on this new redoxmer reveal strong effects of the electrolyte cation on the fluorescence that are useful for probing the solvent microenvironment. Using this probe, we demonstrate proof-of-concept in situ crossover sensing and characterize the effects of electrolyte composition on this crossover. In this way, real-time tracing of redoxmers in a flow cell is demonstrated, paving the way to include still more self-reporting functions into the redoxmers.

Discovery of Energy Storage Molecular Materials Using Quantum Chemistry-Guided Multiobjective Bayesian Optimization

“…In a recent work, Robertson et al have identified that BzNSN molecules with λ abs values ranging from 350 to 400 nm exhibit fluorescence activity. 11 Our DFT calculations of a subset of 1400 BzNSNs also confirm that molecules with λ abs in this range possess the emission wavelength (λ em ) in the visible range (Figure S1). Since the computational evaluation of λ em is significantly more expensive than that of λ abs , we used the latter as an approximate screening indicator of the fluorescence activity.…”

“…8−10 Recently, a BzNSN derivative, CH 3 -AcBzC 6 , was engineered with a π-extended acetamide group, 11 which enabled an orthogonal molecular property, namely fluorescence, to monitor the crossover of the active species and assess the state of health of the battery. 11 Hence, one promising strategy for designing anolyte redoxmers is to perform molecular engineering of the BzNSN scaffold using a wide range of functional groups to achieve the desired properties (e.g., using electron-withdrawing/-donating groups to tune the redox potential). However, high-throughput experimental synthesis and characterization are often a significant bottleneck, and high-fidelity computational methods provide a cost-efficient alternative to enable the design and discovery.…”

Bayesian optimization with known experimental and design constraints for chemistry applications

“…[64][65][66] Furthermore, derivatization of benzothiadiazole enabled self-reporting of battery health by fluorescence emission. 67 In this application we demonstrate our constrained optimization approach for the multi-objective design of retro-synthetically accessible redoxmer molecules. We utilize a previously reported dataset that comprises 1408 benzothiadiazole derivatives (Fig.…”

Clusteroluminescence in Maleimide: from Well-Known Phenomenon to Unknown Mechanism

“…The development of organic fluorophores has revolutionized in various fields such as electronics, 1-3 energy, 4 and medicine. [5][6][7] Organic fluorophores have better structure-property tunability, flexibility, and biocompatibility compared with inorganic light-emitting materials.…”