Last updated on Jan 28, 2024

How can you conduct a cyclic voltammetry test on a battery material?

Cyclic voltammetry (CV) is a widely used technique to characterize the electrochemical properties of battery materials, such as their capacity, stability, and reaction kinetics. In this article, you will learn how to conduct a CV test on a battery material using a potentiostat and a three-electrode cell.

1 Potentiostat setup

A potentiostat is a device that controls the voltage or current applied to an electrochemical cell. To perform a CV test, you need to connect the potentiostat to a computer with a software that can generate and record the voltage and current signals. You also need to calibrate the potentiostat before the test to ensure accurate measurements.

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Dhiksha Mohan

Founder - 1.618 - Biomimicry / Commonwealth Scholar’24 / Energy Storage / Graphene/ Top Nanotechnology Voice/ Nature Photographer/ Multipotentialite
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From my learning, before initiating a CV test on any battery material, the foremost step is conducting a comprehensive literature review. Compile an extensive list of all CV experiments relevant to the chemistry and intended application of the battery material. This list should encompass details such as the counter electrode type, reference electrode type, working electrode specifications, scan rate, frequency, and potential window. Then, commence with the most frequently employed setup and customize the parameters and conditions through an iterative trial-and-error approach.

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Nirmita Roy, PhD.

PhD in Electrochemistry & Wearable Electronics. Skilled in FIB-SEM, EDX, XRD, Raman, FTIR, UV-VIS, Lithography, IC’s, Material Characterization. Innovating Semiconductor & Nanotechnology industry.
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To conduct a cyclic voltammetry test, connect the potentiostat (for example: VersaStat) to a computer with software for signal generation and recording. Calibration ensures accurate measurements. The test involves applying a potential or current sweep to the electrochemical cell and measuring the resulting current or voltage respectively. This data helps analyze the redox reactions in the battery material.

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2 Three-electrode cell assembly

A three-electrode cell consists of a working electrode (WE), a counter electrode (CE), and a reference electrode (RE). The WE is the battery material that you want to test, the CE is a metal wire or plate that balances the current flow, and the RE is a standard electrode that provides a stable reference voltage. You need to assemble the three electrodes in an electrolyte solution that is compatible with the battery material and the RE. The electrodes should be connected to the potentiostat with wires or clips.

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Nirmita Roy, PhD.

PhD in Electrochemistry & Wearable Electronics. Skilled in FIB-SEM, EDX, XRD, Raman, FTIR, UV-VIS, Lithography, IC’s, Material Characterization. Innovating Semiconductor & Nanotechnology industry.
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Cyclic voltammetry (CV) is a powerful technique for analyzing battery materials. In a three-electrode cell, the working electrode (WE) is the battery material under test. The counter electrode (CE) completes the circuit, and the reference electrode (RE) provides a stable voltage reference. The WE’s potential is cycled between two values. As the potential varies, current response is measured, providing information about redox reactions in the battery material. This data can reveal the material’s electrochemical properties, crucial for battery performance.

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3 CV test parameters

To perform a CV test, you need to set some parameters on the software, such as the scan rate, the voltage range, and the number of cycles. The scan rate is the speed at which the voltage changes, usually expressed in mV/s or V/s. The voltage range is the minimum and maximum voltage values that the WE will sweep, usually expressed in V vs. RE. The number of cycles is how many times the voltage will sweep back and forth. These parameters depend on the type and purpose of the battery material, and you may need to optimize them to obtain the best results.

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Dhiksha Mohan

Founder - 1.618 - Biomimicry / Commonwealth Scholar’24 / Energy Storage / Graphene/ Top Nanotechnology Voice/ Nature Photographer/ Multipotentialite
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Tweaking the right CV parameters is extremely important, as it is the language through which you understand the battery material. The blueprints of each cathode and anode material are different, some need a very slow scanning rate to capture their performance on graphs, and some require uniquely long/short potential windows for the redox or capacitive reactions to take place. I strongly recommend revisiting the literature review stage to gain insights into the optimal conditions tailored for each specific battery material.

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Nirmita Roy, PhD.

PhD in Electrochemistry & Wearable Electronics. Skilled in FIB-SEM, EDX, XRD, Raman, FTIR, UV-VIS, Lithography, IC’s, Material Characterization. Innovating Semiconductor & Nanotechnology industry.
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In cyclic voltammetry (CV) testing, setting parameters is crucial. The scan rate determines how quickly the voltage changes over time, affecting the resolution and duration of the test. The voltage range should encompass the potential window where redox reactions occur in the battery material. The number of cycles can affect the stability of the measurement. These parameters should be optimized based on the specific battery material to obtain accurate and meaningful data. Remember, interpretation of CV results requires expertise in electrochemistry.

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4 CV test procedure

Once you have set the parameters, you can start the CV test by clicking a button on the software. The potentiostat will apply a voltage to the WE and measure the current response. The software will plot the current vs. voltage curve in real time, which is called a voltammogram. The voltammogram will show the peaks and valleys that indicate the redox reactions of the battery material. The area under the curve represents the charge transferred, which is proportional to the capacity of the battery material. The shape and position of the curve can also reveal the stability and kinetics of the battery material.

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5 CV test analysis

After the CV test is finished, you can save and export the data from the software. You can then analyze the data using various methods and tools, such as peak integration, peak fitting, Tafel analysis, or Butler-Volmer analysis. These methods and tools can help you calculate and compare the parameters of interest, such as the specific capacity, the coulombic efficiency, the charge transfer resistance, or the reaction rate constant. You can also plot and compare the voltammograms of different battery materials or different test conditions to evaluate their performance and behavior.

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6 CV test limitations

While CV is a powerful and versatile technique, it also has some limitations that you should be aware of. For example, CV may not be suitable for battery materials that have slow reaction kinetics, high internal resistance, or irreversible reactions. CV may also be affected by factors such as the electrode surface area, the electrolyte concentration, the temperature, or the presence of impurities. Therefore, you should always perform CV tests with caution and proper controls, and complement them with other techniques, such as impedance spectroscopy, galvanostatic charge-discharge, or differential capacity analysis.

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