Concentration shift experiment with an electrode of active material for precise electrochemical analysis

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Accurate evaluation of battery active material electrochemical properties is crucial for performance optimization.
• Existing methods may not fully isolate the intrinsic properties of individual active material particles.
• Understanding resistance contributions at the single-particle level is key to improving electrode design.

Purpose of the Study:

• To develop and apply a novel 'concentration shift experiment' for precise electrochemical evaluation.
• To measure and calculate resistance components and apparent activation energy (Ea) of LiCoO2 single particles.
• To investigate the relationship between LiCoO2 concentration and electrode resistance.

Main Methods:

• Single-particle electrochemical measurement (SPEM) under extremely dilute conditions (≈0%).
• Fabrication of diluted electrode sheets (DES) with varying LiCoO2 concentrations (1%–100%).
• Alternating current impedance measurements to extract resistance components and calculate Ea.

Main Results:

• Apparent activation energy (Ea) for LiCoO2 single particles was determined to be 27 kJ mol⁻¹, significantly lower than bulk electrodes.
• Electrode resistance decreased non-linearly with increasing LiCoO2 concentration, suggesting percolation and inhomogeneity.
• SPEM successfully isolated and analyzed fundamental LiCoO2-originated resistance and Ea.

Conclusions:

• The concentration shift experiment combined with SPEM provides a powerful tool for isolating and evaluating intrinsic active material properties.
• The low Ea indicates a more efficient charge transport mechanism within individual LiCoO2 particles compared to bulk electrodes.
• Understanding particle-level behavior, including percolation and inhomogeneity, is critical for optimizing overall electrode performance.