Paradoxical roles of hydrogen in electrochemical performance of graphene: High rate capacity and atomistic origins
Atomic hydrogen exists ubiquitously in graphene materials made by chemical methods. Yet determining the effect of hydrogen on the electrochemical performance of graphene remains a significant challenge. Here we report the experimental observations of high rate capacity in hydrogen-treated 3-dimensional (3D) graphene nanofoam electrodes for lithium ion batteries. Structural and electronic characterization suggests that defect sites and hydrogen play synergistic roles in disrupting sp 2 graphene to facilitate fast lithium transport and reversible surface binding, as evidenced by the fast charge-transfer kinetics and increased capacitive contribution in hydrogen-treated 3D graphene. In concert with experiments, multiscale calculations reveal that defect complexes in graphene are prerequisite for low-temperature hydrogenation, and that the hydrogenation of defective or functionalized sites at strained domain boundaries plays a beneficial role in improving rate capacity by opening gaps to facilitate easier Li penetration. Additional reversible capacity is provided by enhanced lithium binding near hydrogen-terminated edge sites. Furthermore, these findings provide qualitative insights in helping the design of graphene-based materials for high-power electrodes.
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- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Publication Date:
- Report Number(s):
- LLNL-JRNL-670804
Journal ID: ISSN 2045-2322
- Grant/Contract Number:
- AC52-07NA27344
- Type:
- Accepted Manuscript
- Journal Name:
- Scientific Reports
- Additional Journal Information:
- Journal Volume: 5; Journal Issue: C; Journal ID: ISSN 2045-2322
- Publisher:
- Nature Publishing Group
- Research Org:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org:
- USDOE
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; 25 ENERGY STORAGE; graphene; hydrogen; electrochemical performance; first principles; pseudocapacitance
- OSTI Identifier:
- 1251039