Battery Cycler Microcalorimeter Solution for Lithium-Ion Battery Analysis

The Battery Cycler Microcalorimeter solution combines TA Instruments’ TAM IV Isothermal Microcalorimeter with BioLogic’s VSP-300 Potentiostat. By integrating these instruments, the system simplifies the most demanding and labor-intensive parts of battery calorimetry while enhancing the technology’s performance and practical application. 

Control of both the potentiostat and calorimeters, along with the import, correlation, and analysis of their data, is completed through the integrated TAM Assistant software.

Pre-wired battery lifters serve as calorimeter inserts that hold the batteries and establish electrical connections with the potentiostat. These lifters are tailored for three widely used lithium-ion battery formats: 18650 cylindrical cells, pouch cells, and coin cells.

As a result, this solution is a valuable instrument for research and development laboratories and can provide more detailed insight than many currently available techniques.

Introduction

Conventional battery chemistry research has generally treated materials characterization and thermal analysis as separate activities from electrochemical testing.

Materials characterization was used to measure newly developed battery components and assess how they changed following cell failure. Thermal analysis, meanwhile, supported the development of improved thermal management systems for practical applications.

Much of the understanding of battery performance, the chemistry occurring inside the cell, and its evolution over time was derived from electrochemical measurements.

However, this traditional workflow left important gaps in chemical understanding.¹ Batteries are highly dynamic systems in which electrochemical, chemical, and structural transformations occur during every cycle.

Because electrochemical analysis only detects processes that influence electrochemical reactions, other chemical, phase, and structural changes remain uncharacterized. Numerous intermediate stages exist between a new battery cell and a failed one, and understanding degradation requires information beyond what conventional techniques can provide.^1,2

Current approaches increasingly combine electrochemistry with an additional analytical technique to quantify battery processes during operation. A leading strategy is to integrate high-resolution isothermal microcalorimetry with electrochemical measurements.^3–6

Evaluating the thermal behavior of lithium-ion batteries in response to electrochemical stimuli can provide substantially more information than electrochemical measurements alone.

Alongside general thermal management information, calorimetry can quantify parasitic reactions, meaning non-reversible reactions that contribute to degradation, as well as structural changes, lithium plating, self-discharge rates, and reactions associated with SEI layer formation and decomposition.^3–8

Such information can support the development and refinement of battery formulation chemistry. Battery calorimetry can also support quality control by improving the identification of poorly manufactured cells, since the technique is inherently compatible with commercial cell formats.

Although electrochemical calorimetry is a powerful analytical method, the complexity and sensitivity of the experiments can make it difficult for many researchers to implement. Hyphenated and hybrid instrument methods often require lengthy post-experiment processing to align signals from different devices.

They may also require several software platforms, forcing users to coordinate experiment start times and operating parameters manually. The Battery Cycler Microcalorimeter solution addresses these limitations by integrating the calorimeter and potentiostat at both the hardware and software levels, thereby simplifying battery calorimetry.

Battery Cycler Microcalorimeter Solution

The Battery Cycler Microcalorimeter solution combines the BioLogic VSP-300 Potentiostat with the TA Instruments TAM IV Isothermal Microcalorimeter (Figure 1). Through the integrated TAM Assistant software, both instruments can be controlled, including experiment setup and the real-time integration of heat-flow and electrochemical measurements.

The pre-wired lifters function as calorimeter inserts that contain the batteries and establish electrical contact with the potentiostat. They are designed to transfer heat generated by the battery into the calorimeter while reducing interference caused by ambient temperature variation and wire heating. Battery contact is established using a conductive spring clip, eliminating the need for soldering or supplementary insulation.

Three lifter configurations are available for commonly used lithium-ion battery sizes. The first, the coin cell lifter, accommodates coin or button cells with diameters of up to 23 mm. It can be used with any 20 mL calorimeter on the TAM IV, including the microcalorimeter and the three-unit multicalorimeter configuration.

Figure 1. The Battery Cycler Microcalorimetry solution integrates TA Instruments’ TAM IV Isothermal Microcalorimeter with BioLogic’s VSP-300 Potentiostat. The pre-wired lifters house the batteries and make electrical contact with the potentiostat. Both instruments are controlled through an integrated TAM Assistant software. Image Credit: TA Instruments

The macrocalorimeter lifter accommodates standard 18650 cylindrical cells, which are frequently used in electric vehicles. The Micro-XL lifter is designed for pouch cells measuring up to 50 mm in width, 94 mm in length, and 12 mm in thickness. An adjustable clamp with conductive contacts secures the tabs and accommodates different tab spacings.

The TAM IV calorimeters can be arranged in several configurations to increase throughput according to testing requirements. For example, when the TAM IV is equipped with four multicalorimeters and two VSP-300 potentiostats, each providing six channels, users can test 12 coin cells simultaneously in separate experiments.

Integrated Software

From a workflow standpoint, the software connection between the TAM IV and VSP-300 is one of the most important features of the Battery Cycler Microcalorimeter. TAM Assistant enables simultaneous control of the TAM IV and VSP-300 Potentiostat, allowing battery calorimetry experiments to be conducted through one software interface.

The battery experiment wizards are presented in Figure 2. These wizards guide users through method selection, parameter configuration, sample loading, and confirmation of baseline stability.

Figure 2. New experiment wizard in TAM Assistant. The user can choose from a variety of preset experiments and program custom run sequences for maximum flexibility. Image Credit: TA Instruments

The available methods are outlined below.

Manual: Enables customized experiments by allowing users to select actions, waiting periods, and event markers within the run-sequence menu.

Heat management (CCCV): Records heat flow during battery cycling and is primarily intended for thermal management studies. This method applies different charging profiles, including variable charge and discharge rates, using constant-current constant-voltage (CCCV) parameters.

Entropy changes: Uses a slow cycle at C/20 followed by a very slow cycle at C/100 to provide high-resolution information about the structural and phase changes associated with lithiation and delithiation.

First-cycle reaction (SEI): Examines SEI formation by applying a low charging current in the low-voltage region where SEI generally forms, typically below 3 V. A higher charging current is then applied until the standard upper voltage limit is reached, typically 4.2 V.

Full-cycle parasitics: Determines parasitic power across the complete voltage range. The term “parasitics” refers broadly to non-reversible side reactions that contribute to battery degradation.

Narrow-cycle parasitics: Determines parasitic power within a limited voltage range. This approach is faster when the investigation is restricted to specific voltage windows.

Self-discharge: Measures the self-discharge rate by combining the conventional approach of monitoring open-circuit voltage over time and then discharging the cell to determine remaining capacity with a thermal approach that integrates the total heat generated during the open-circuit period.

Figure 3. Real-time data integration of the potentiostat and calorimeter signals. Voltage and heat flow labels were added for clarity. Image Credit: TA Instruments

During an experiment, thermal and electrochemical signals are displayed together in a single window (Figure 3). For the resulting measurements to be useful, the signals must be aligned with a high degree of precision.

Both data sets are timestamped and automatically matched by the software during import. This provides a major improvement over manual data processing, which is more time-consuming and can introduce transcription errors.

Analysis Tools

Once an experiment is complete, the results file provides several analysis options. The integrated TAM Assistant software automatically calculates important values and displays them either in a table or as a graph. Users can select from multiple x- and y-axis variables, overlay several cycles, and distinguish between charging and discharging data (see Figure 4).

These functions were developed to provide flexibility, speed, and ease of use, enabling users to identify trends and features in the data more efficiently. The summary table displays averaged or accumulated signals, including coulombic efficiency and mean parasitic power.

Additional information about the calculations, underlying theory, and calibration is available in the TA Instruments application note entitled “Determination of Parasitic Power in Lithium-Ion Batteries using the Battery Cycler Microcalorimeter Solution.”

Figure 4. Automated Plotting of raw signals and calculated values. Image Credit: TA Instruments

Conclusion

Calorimetric analysis of complete battery cells is useful for thermal management, investigations of electrolyte additives, active material formulation, and quality control. The complexity of the experiments and the amount of manual data processing previously limited access to this technology. By integrating the TAM IV with the VSP-300 at both the hardware and software levels, the Battery Cycler Microcalorimeter solution improves the accessibility, reliability, and overall practical value of battery calorimetry.

Acknowledgments

Produced using materials originally authored by Jeremy May, PhD, from TA Instruments.

References and Further Reading

1. Liu, D., et al. (2019). Review of Recent Development of In Situ/Operando Characterization Techniques for Lithium Battery Research. Advanced Materials, 31(28). DOI:10.1002/adma.201806620. https://advanced.onlinelibrary.wiley.com/doi/abs/10.1002/adma.201806620.
2. Boebinger, M.G., et al. (2020). Understanding Transformations in Battery Materials Using in Situ and Operando Experiments: Progress and Outlook. ACS Energy Lett., 5(1), pp.335–345. DOI:10.1021/acsenergylett.9b02514. https://pubs.acs.org/aelccp/article-abstract/5/1/335/1675750/Understanding-Transformations-in-Battery-Materials?redirectedFrom=fulltext.
3. Krause, L.J., Jensen, L.D. and Dahn, J.R. (2012). Measurement of Parasitic Reactions in Li Ion Cells by Electrochemical Calorimetry. Journal of The Electrochemical Society, 159(7), pp.A937-A943. DOI:10.1149/2.021207jes. https://iopscience.iop.org/article/10.1149/2.021207jes/meta.
4. Downie, L.E., Hyatt, S.R. and Dahn, J.R. (2015). The Impact of Electrolyte Composition on Parasitic Reactions in Lithium Ion Cells Charged to 4.7 V Determined Using Isothermal Microcalorimetry. Journal of The Electrochemical Society, 163(2), pp.A35-A42. DOI:10.1149/2.0081602jes. https://iopscience.iop.org/article/10.1149/2.0081602jes/meta.
5. Krause, L.J., Jensen, L.D. and Chevrier, V.L. (2017). Measurement of Li-Ion Battery Electrolyte Stability by Electrochemical Calorimetry. Journal of The Electrochemical Society, 164(4), pp.A889-A896. DOI:10.1149/2.1651704jes. https://iopscience.iop.org/article/10.1149/2.1651704jes/meta.
6. Kunz, A., et al. (2022). Time-Resolved Electrochemical Heat Flow Calorimetry for the Analysis of Highly Dynamic Processes in Lithium-Ion Batteries. Journal of The Electrochemical Society, 169(8), p.080513. DOI:10.1149/1945-7111/ac8625. https://iopscience.iop.org/article/10.1149/1945-7111/ac8625/meta.
7. Burns, J.C., et al. (2013). Predicting and Extending the Lifetime of Li-Ion Batteries. Journal of The Electrochemical Society, 160(9), pp.A1451-A1456. DOI:10.1149/2.060309jes. https://iopscience.iop.org/article/10.1149/2.060309jes/meta.
8. Downie, L.E., et al. (2013). In Situ Detection of Lithium Plating on Graphite Electrodes by Electrochemical Calorimetry. Journal of The Electrochemical Society, 160(4), pp.A588-A594. DOI:10.1149/2.049304jes. https://iopscience.iop.org/article/10.1149/2.049304jes/meta.

This information has been sourced, reviewed, and adapted from materials provided by TA Instruments.

For more information on this source, please visit TA Instruments.