Constant current constant voltage (CCCV) cycling with INTELLO

Importance of the topic

Charge/discharge cycling is a cornerstone technique in battery research, providing essential insights into performance, lifetime and safety. By repeatedly charging and discharging cells under controlled conditions, researchers can evaluate capacity retention, coulombic efficiency and rate capability. Such data guide materials development, quality control and failure analysis for batteries in consumer electronics, electric vehicles and grid storage.

Study objectives and overview

This Application Note presents the workflow for constant current/constant voltage (CCCV) cycle testing using the INTELLO software platform paired with Metrohm Autolab instrumentation. It covers terminology, cycle construction, recommended plots and example results obtained for a Li-ion coin cell. The aim is to demonstrate how to configure robust battery cycling sequences and extract key metrics to characterize cell behavior.

Methodology and Instrumentation

Researchers define cell properties (voltage limits, capacity) and construct nested cycle commands in INTELLO. Core commands include:

• CC Charge/Discharge: constant current step
• CV Charge/Discharge: constant voltage step held until a current cutoff or timeout
• Rest: open-circuit relaxation
• EIS: electrochemical impedance spectroscopy at any sequence point

C-rates are specified relative to the cell’s theoretical or nominal capacity (1C fully (dis)charges in one hour). Users can set end conditions such as maximum cycle time or minimum coulombic efficiency. Example sequence: CCCV charge to 4.2 V (1 C) until current drops below 10 mA or 120 min, 30 min rest, 1 C discharge, 30 min rest, repeat.

Instrument setup in the example:

• Metrohm Autolab VIONIC potentiostat/galvanostat
• Duo coin cell holder
• Test cell: commercial Li-ion LIR2450 coin cell (120 mAh)

Key results and discussion

INTELLO generates standard diagnostic plots for cycle analysis:

1. Voltage & current vs time (E & i vs T): reveals charge/discharge plateaus and irregularities indicating reaction dynamics or cell faults.
2. Voltage vs capacity (E vs Q+/Q–): highlights phase transitions and resistance effects; capacity fade manifests as curve shortening.
3. Voltage vs cumulative capacity (E vs |Q|): tracks shifts due to capacity loss across cycles.
4. Charge/discharge capacity vs cycle number (Q+, Q– vs cycle): quantifies capacity retention over time.
5. Coulombic efficiency vs cycle number (CE vs cycle): monitors electron transfer efficiency; drop in CE signals side reactions or degradation.
6. Relative capacity vs cycle (RC vs cycle): assesses capacity retention relative to the cell’s rated capacity; rapid decline suggests stress from high C-rate.

In the example, the 120 mAh coin cell charged at 1 C and cycled showed progressive capacity fade and a gradual drop in coulombic efficiency, underscoring the need to optimize charge protocols.

Benefits and practical applications

This workflow enables:

• Rapid configuration of complex cycle sequences with safety limits.
• Automated generation of diagnostic plots for performance evaluation.
• Normalization of capacity data to active material mass or area for material screening.
• Early detection of failure mechanisms via cycle-resolved metrics.

Such capabilities support R&D, quality control and lifetime testing in battery production and academic research.

Future trends and opportunities

Advances likely include integration of high-throughput cycling modules, machine-learning models for predictive lifetime estimation and in situ diagnostics coupling cycling with spectroscopic or thermal measurements. Expanding EIS automation and real-time data analytics will enhance understanding of degradation pathways and accelerate material screening.

Conclusion

The INTELLO platform, combined with a versatile potentiostat such as VIONIC, provides an intuitive environment for CCCV and CC cycling, facilitating comprehensive battery characterization. Standardized cycle building, customizable end conditions and a suite of analytical plots streamline the evaluation of capacity, efficiency and aging behavior, supporting informed decisions in battery development.

Reference

Application Note AN-BAT-014: Constant current constant voltage (CCCV) cycling with INTELLO, Metrohm Autolab.