Cooperative Conformational Change of a Single Organic Molecule for Ultrafast Rechargeable Batteries

Abstract

We unveil that the conformational change of a single organic molecule during the redox reaction leads to impressive battery performance for the first time. We propose the model material, a phenoxazin-3-one derivative, as a new redox-active bioinspired single molecule for the Li-ion rechargeable battery. The phenoxazin-3-one cathode delivered a high discharge capacity (298 mAh g–1) and fast rate capability (65% capacity retention at 10 C). We elaborate the redox mechanism and reaction pathway of phenoxazin-3-one during Li+-coupled redox reaction. The molecular structure alteration of phenoxazin-3-one during the lithium-coupled electron transfer reaction enables strong π–π interaction between 2Li-phenoxazin-3-one and carbon, which was evidenced by operando Raman spectroscopy and density functional theory calculation. Our work provides in-depth understanding about the conformational molecular switch of the single molecule during Li+-coupled redox reaction and insight into the design of a new class of organic electrode materials.

Self‐Assembled Carbon Superstructures Achieving Ultra‐Stable and Fast Proton‐Coupled Charge Storage Kinetics

“…[ 29 ] The capture ability of O‐1 to H atoms is boosted to deliver a binding energy of −4.38 eV (Figure 5i), indicating the robust electrochemically reactivity of carbonyl group. [ 30 ] In addition, top (Figure 5j) and side (Figure S13, Supporting Information) views of the electron density difference were demonstrated by subtracting the charge densities of H and C atoms from N‐6, N‐5, and O‐1 to understand the bonding nature of the adsorbed H atoms in depth. The charge depletion of H and much charge accumulation around N/O active regions are explicitly observed.…”

Reversible Redox Chemistry in a Phenoxazine-Based Organic Compound: A Two-Electron Storage Negolyte for Alkaline Flow Batteries

“…The authors evidenced a competition of H + ions for the same chelating groups (negative charged groups) of GAL ox 2– species. Li-ion pairing and H + ion transfer competition was also observed during the reduction process of a phenoxazine-3-one structure used in Li-ion batteries . To be consistent with such reported mechanism, the next set of chemical and electrochemical equations are proposed to explain a competition mechanism during the reduction process of GAL ox 2– species in solution ( sol ), GAL ox(sol) 2– , to form reduced ( red ) species, GAL red(sol) 4– , in hydroxide salt solutions which provide n number of protons H + and positive charged counterions M + (K + , Na + and Li + ): boldGAL ox ( sol ) 2 − + 2 normale − ⇌ boldGAL red ( sol ) 4 − goodbreak0em1em⁣ E 0 , k normals boldGAL red ( sol ) 4 − + n normalM + ⇌ normalM italicn boldGAL red ( sol ) n − 4 goodbreak0em1em⁣ K ion = k normalf 1 / k normalb 1 boldGAL red ( sol ) 4 − + …”

“…The authors evidenced a competition of H + ions for the same chelating groups (negative charged groups) of GAL ox 2– species. Li-ion pairing and H + ion transfer competition was also observed during the reduction process of a phenoxazine-3-one structure used in Li-ion batteries . To be consistent with such reported mechanism, the next set of chemical and electrochemical equations are proposed to explain a competition mechanism during the reduction process of GAL ox 2– species in solution ( sol ), GAL ox(sol) 2– , to form reduced ( red ) species, GAL red(sol) 4– , in hydroxide salt solutions which provide n number of protons H + and positive charged counterions M + (K + , Na + and Li + ): Regardless of the number of H + and M + ions interacting with each reduced GAL red(sol) 4– species to form M n GAL red(sol) n –4 and/or H n GAL red(sol) n –4 aggregates, both ion pairing and proton transfer reactions should occur as a fast and reversible process, since no significant changes in the shape and height of E pa signal are observed when modifying the amount of hydroxide salt and/or neutral salt in solution.…”

“…Li-ion pairing and H + ion transfer competition was also observed during the reduction process of a phenoxazine-3-one structure used in Li-ion batteries. 43 To be consistent with such reported mechanism, the next set of chemical and electrochemical equations are proposed to explain a competition mechanism during the reduction process of GAL ox 2− species in solution (sol), GAL ox(sol) 2− , to form reduced (red) species, GAL red(sol) 4− , in hydroxide salt solutions which provide n number of protons H + and positive charged counterions M + (K + , Na + and Li + ):…”

Octaphyrin(1.0.1.0.1.0.1.0) as an Organic Electrode for Li and Na Rechargeable Batteries

“…The primary factor is the durability of the organic host molecular conformation with ion compositional variation during redox‐interconversions and vital kinetics of ion diffusions (insertion/desertions) to obtain optimal organic batteries. [ 8 ] Moreover, redox processes during charging/discharging are supposed to be perfectly reversible and chemically tunable with multiple oxidation states, furnishing the characteristic electrochemistry.…”