Skip to content

Development and Applications of an eReaxFF Force Field for Graphitic Anodes of Lithium-Ion Batteries

Summary

The work introduces an eReaxFF parametrization for graphitic carbon that carries an explicit electronic degree of freedom, aimed at large-scale atomistic models of electron conduction and finite-bias-like scenarios in Li-ion battery anodes. The motivation is to move beyond fixed charge-equilibration pictures when excess electrons localize at defects or under applied bias. The parametrization is checked against quantum-chemistry reference data (including electron affinities and equations of state), and simulations reproduce qualitative trends in electron conductivity for pristine and defective graphitic models across temperature and applied voltage. Excess electron localization near a defect from eReaxFF agrees well with DFT. Simulations also show lithium metal plating initiated by electron transfer from the graphene surface toward exposed Li ions, illustrating a path toward modeling electrode–electrolyte phenomena with explicit electronics.

Methods

A — eReaxFF parameterization / model

  • eReaxFF: ReaxFF extended with explicit electronic degrees of freedom for graphitic carbon—bond-order-dependent coupling of nuclei to excess charge / carrier populations.

B — Validation vs QM

  • DFT (or related QC) benchmarks on energies, affinities, EOS; defect charge localization vs eReaxFF on surface imperfections.

C — Production MD (battery-relevant interfaces)

  • Graphite models with defects; temperature and bias/voltage conditions in J. Electrochem. Soc. Methods.
  • Li intercalation / plating trajectories with interfacial electron transfer tracked alongside ion positions.

D — Experiments

  • None; qualitative comparison to conductivity trends from literature as discussed.

Integrated protocol (with locators in the version-of-record PDF): 1 — MD / eReaxFF dynamics. Engine: LAMMPS-class eReaxFF molecular dynamics; graphene / graphitic supercell and defect models with 3D PBC; NVT/NVE-class integration with a thermostat and fs-scale timestep; ps–ns equilibration/production as in J. Electrochem. Soc. 169 110540. Bias and voltage enter through the explicit electronic DOF (not “E-field: N/A” in the electrochemical sense). Barostat: N/A for the illustrations summarized. Hydrostatic pressure: N/A in the main abstract narrative. N/A in this short note for full atom counts and one-line E-field magnitudes—read the Methods/SI. Replica / enhanced sampling: N/A to the eReaxFF demonstrations highlighted. 2 — eReaxFF training. Parent ReaxFF/eReaxFF; DFT/QM training energies/forces, affinity and equation-of-state targets, optimization, and validation data are described in the article; N/A to reproduce every table here.

Findings

Outcomes / mechanisms: eReaxFF reports qualitative electronic conduction vs. temperature and voltage/bias in pristine and defective graphite; DFT-consistent excess charge at imperfections. Li plating can be shown from interfacial electron transfer to lithium ions—a route toward electrode–electrolyte phenomena with explicit carriers, but not a quantitative transport calibration. Comparisons: versus QM on defects; vs experiment is trend-level, not a transport coefficient benchmark. Sensitivity: temperature and bias; defect density changes local trapping. Authored limitations (quantitative vs real anodes) remain in the JES text. Corpus / KB — p1–2 extract misses full protocol numbers; use the open PDF (169, 110540) for citable detail and for any SI replica; this page does not add chemistry beyond those sources.

Limitations

Qualitative conductivity matching; users should check quantitative transport numbers and bias ranges against experiment and higher-level electronic-structure theory for their specific cells. System sizes in interfacial battery modeling often under-resolve long-wavelength polarization and image-charge effects that real electrodes supply, so the eReaxFF stage is best viewed as a mechanistic microscope for local electron–ion coupling rather than a drop-in replacement for continuum transport solvers. J. Electrochem. Soc. 169, 110540 is the citable volume/issue anchor for the open PDF in this corpus.

Relevance to group

Core eReaxFF development at Penn State for battery anodes and graphitic carbon—extends the ReaxFF lineage toward electrochemical fidelity.

Citations and evidence anchors

Reader notes (navigation)