Hydrogen-Type Binding Sites in Carbonaceous Electrodes for Rapid Lithium Insertion

Direct pyrolysis of coronene at 800 & DEG;C produces low-surface-area,nanocrystalline graphitic carbon containing a uniquely high contentof a class of lithium binding sites referred to herein as hydrogen-typesites. Correspondingly, this material exhibits a distinct redox coupleunder electrochemical lithiation that is characterized as intermediate-strength,capacitive lithium binding, centered at & SIM;0.5 V vs Li/Li+. Lithiation of hydrogen-type sites is reversible and electrochemicallydistinct from capacitive lithium adsorption and from intercalation-typebinding between graphitic layers. Hydrogen-type site lithiation canbe fully retained even up to ultrafast current rates (e.g., 15 A g(-1), & SIM;40 C) where intercalation is severely hamperedby ion desolvation kinetics; at the same time, the bulk nature ofthese sites does not require a large surface area, and only minimalelectrolyte decomposition occurs during the first charge/dischargecycle, making coronene-derived carbon an exceptional candidate forhigh-energy-density battery applications.

Automated summary

Direct pyrolysis of coronene at 800°C produces low-surface-area, nanocrystalline graphitic carbon with a uniquely high content of hydrogen-type lithium binding sites. The lithiation of these sites is characterized by intermediate-strength, capacitive lithium binding, and is distinct from both capacitive lithium adsorption and intercalation-type binding. The lithiation of hydrogen-type sites is reversible and remains stable even at ultrafast current rates, making coronene-derived carbon an exceptional candidate for high-energy-density battery applications.