Multiscale dynamics of charging and plating in graphite electrodes coupling operando microscopy and phase-field...

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Phase separation dynamics in graphite anodes are critical for lithium plating.
• Lithium plating is a major cause of degradation in automotive lithium-ion batteries, impacting safety and fast-charging capabilities.

Purpose of the Study:

• To investigate the rate-dependent spatial dynamics of phase separation and lithium plating in graphite electrodes.
• To provide a mechanistic understanding of multistage phase separation, plating, and lithium exchange phenomena.

Main Methods:

• Operando high-resolution optical microscopy.
• Multi-dimensional phase-field modeling (1D+1D to 3D) using non-equilibrium thermodynamics.
• Image-based 3D phase-field modeling.

Main Results:

• Observed strong dependence of intra-particle lithiation heterogeneity on particle size, shape, orientation, surface condition, and C-rate.
• Revealed early onset of plating due to lithiation heterogeneity, spatially resolved by a 3D model.
• Highlighted distinct relaxation processes at different states-of-charge (SOCs), with faster redistribution at intermediate SOCs.

Conclusions:

• Developed a mechanistic understanding of phase separation and plating dynamics in graphite electrodes.
• Demonstrated the impact of particle-level heterogeneities on plating propensity.
• Provided physics-based insights into SOC-dependent relaxation efficiency for developing advanced fast-charging protocols to suppress plating.