Optimize battery protocols for fast-charging & aging studies with 3-electrodes

Traditional two-electrode battery measurements capture overall cell behavior but cannot attribute performance limitations or degradation to specific electrodes. Three-electrode configurations address this by adding a reference electrode to independently monitor anode and cathode potentials -particularly valuable when multiple degradation mechanisms (lithium plating, SEI growth, structural changes) operate simultaneously during fast charging.

The challenges in traditional battery testing

Traditional two-electrode configurations only provide the overall cell behavior without revealing which electrode is responsible for performance limitations or degradation.

Three-electrode configurations: a partial solution

Adding a reference electrode enables researchers to decouple individual electrode contributions, theoretically pinpointing where problems originate. However, most commercial potentiostats are designed primarily for classical electrochemistry experiments rather than battery research and only record the working electrode potential versus the reference while controlling current between working and counter electrodes. The counter electrode potential and full-cell voltage remain unmeasured.

Figure 1: Configuration for a battery with a reference electrode.

This creates an operational constraint: researchers can monitor either one electrode or the full cell, but not both simultaneously. For battery studies requiring comprehensive data, this necessitates either multiple experimental runs with different connection configurations or post-experiment calculations based on assumptions about the unmeasured electrodes.

The ideal battery characterization system requires simultaneous recording for capturing all three critical measurements in real-time (anode potential versus reference, cathode potential versus reference, and full-cell voltage) and flexible control that allows researchers to set cutoff conditions and experimental triggers based on any of these three measurements.

Advanced BioLogic Solutions: The Complete Picture

BioLogic potentiostat/galvanostats, paired with EC-Lab^® software, address these limitations by recording all potentials simultaneously while the full cell voltage is controlled.

Note: Associated energy and power variables are also available for all voltage. When “Energy/W.h” is ticked in the “Safety/Adv.Settings” tab, energy calculations are performed by firmware at each time base (rather than only at recorded data points) for improved temporal resolution and accuracy compared to post-processing approaches.

Figure 2: Potential control and record option in the Safety/Adv.Settings tab, for both Essential and Premium range potentiostat

And for fine-tuning Constant Current Constant Voltage (CCCV) protocol, EC-Lab^® software enables multi-criteria protocol control. Voltage limits can be set and held on the anode and/or cathode, and/or full cell, all during the same experiment (independent of the potential control mode).

Additional limits such as charge, state of charge, energy, and temperature thresholds can be incorporated in the protocol. These limits can operate simultaneously, stopping the experiment when any criterion is met.

Figure 3: CCCV settings on EC-Lab® with up to 4 conditional limits by step and various limit variable options.

Key advantages: better battery research insights

Complete electrode monitoring without compromise

All relevant potentials are tracked continuously, eliminating the need for calculations, assumptions, or multiple experimental runs to piece together the full story.

Enhanced CCCV protocol capabilities.

Traditional CCCV protocols rely exclusively on full-cell voltage. A typical approach charges at high current until reaching 4.2 V, then holds that voltage until current tapers. While simple, this method provides no protection against electrode-specific degradation mechanisms.

The ability to monitor all electrodes simultaneously enables fundamentally new charging protocols that protect battery health while maximizing charging speed. For example, when developing a fast charging protocol, charging can terminate if:

• the anode drops below 0 V vs Li/Li⁺, to avoid lithium plating and dendrite growth
• OR if full-cell voltage exceeds 4.2 V, to prevent cathode structural degradation
• OR if the cathode reaches a predefined stress threshold.

Degradation attribution made simple

As capacity diminishes during cycling, comparing all three signals reveals exactly which electrode drives the aging process.

Post-analysis flexibility

Complete datasets enable multiple analytical approaches after data collection. Researchers need not commit to a single analysis strategy before beginning the experiment.

Conclusion

This comprehensive approach transforms battery characterization from a constraint-limited process into one where complete electrochemical visibility enables complete insights. For researchers investigating fast-charging protocols, degradation mechanisms, or electrode-specific phenomena, the visibility into both electrodes and the full cell is essential for rigorous analysis.