To celebrate the holiday season and the re-release of Ionworks Studio, we featured "12 (business) days of electrochemical testing". Each day we pick a test, give a little bit of information about it, and show you how to run it in Ionworks. 🔋 🎄

Following the whole series, you can also see the Ionworks Studio UI evolving in real time as we add features and improve the visualization!

1. GITT

On the first day of Christmas Ionworks simulated for me... a cycle of GITT 🔁 ⚡ 🛏️

The Galvanostatic Intermittent Titration Technique (GITT) is one of the cornerstones of electrochemical testing. It is used to determine the diffusivity of intercalated lithium in the active material and the open-circuit potential. The test consists of applying short pulses at a relatively low C-rate, followed by long periods of rest, until the battery is fully charged or discharged.

The main advantage of GITT is that it isolates the Open Circuit Voltage (OCV), resistance, and diffusion dynamics in the particles, and therefore makes it easy to fit open-circuit, kinetic, and particle diffusion parameters. Since each pulse takes place at a different State of Charge (SOC), it enables fitting each parameter as a function of SOC. And the long rest steps mean that temperature stays relatively constant in the thermal chamber, even for larger format cells.

The main drawback is time: this test takes several days due to the long equilibration rest steps required, and even longer if repeating at multiple temperatures.

2. Pseudo-OCV

On the second day of Christmas Ionworks simulated for me... pseudo-OCV 🔋🐢🪫

Measuring the pseudo-OCV of a battery requires performing a discharge (or charge) at an extremely low current, so the influence of internal resistances is minimal. Even though the measured voltage is not exactly the open-circuit voltage (as measured, for example, using GITT) it provides a good approximation in a fraction of the time. As the number of measured points in a pseudo-OCV is typically much larger than in GITT, it is very well-suited for differential voltage analysis.

How low should you go? As with everything else there are trade-offs, in this case between reducing overpotentials and reducing test time. C/20 is the highest we would recommend, and between C/50 and C/30 is ideal. Some people have even gone as low as C/100 !

3. Constant current discharge

On the third day of Christmas Ionworks simulated for me... a discharge rate capability test 🔋 ⏩ 🪫

How much energy, capacity, and power can your battery deliver under different loads? That’s the question discharge rate capability tests answer. By discharging the battery at a constant current between two set voltages, or states of charge, across various rates, this test reveals how a battery performs under different operating conditions.

This isn’t just about current, though. The same experiment can be performed with constant power instead of constant current, measuring the total discharge energy instead of capacity. Understanding the trade-offs between power and energy delivery is key to designing systems that perform reliably across a range of use cases—from powering EVs up steep inclines to running electronics on standby.

4. Constant current charge

On the fourth day of Christmas Ionworks simulated for me... a charge rate capability test 🪫⏩🔋

How fast can you charge your battery without compromising its performance or longevity? That’s where charge rate capability tests come in. Just like their discharge counterpart, these tests are essential for understanding battery behavior—this time, during charging.

The test involves charging the battery between two defined SOC limits using a constant-current constant-voltage (CCCV) protocol, all at various rates. The result? A deeper understanding of how a battery performs at different charging speeds, along with insights into the trade-offs between capacity retention, heat generation, and charging time.

This experiment is particularly valuable for evaluating fast-charging strategies within specific SOC ranges, where efficiency and safety are top priorities. Whether you’re optimizing for rapid EV charging or extending the life of consumer electronics, charge rate capability tests offer the data you need to make informed decisions.

5. Cyclic Voltammetry

On the fifth day of Christmas, Ionworks simulated for me… Cyclic Voltammetry! 🔋 🔃

Cyclic Voltammetry (CV) is a powerful yet often under-the-radar electrochemical technique. By sweeping the electrode potential back and forth and measuring the resulting current, CV helps pinpoint exactly where oxidation and reduction reactions take place—and how stable and reversible they really are.

This early-stage characterization tool shines when it comes to:
• Identifying redox couples 🔍
• Estimating diffusion coefficients ⚖️
• Evaluating surface films like the SEI 🔬

However, CV alone isn’t the whole story. It doesn’t directly predict long-term battery life and should be paired with tests like GITT, rate capability, or EIS to give you a 360° view of your battery’s performance potential.

The good news? Ionworks Studio can simulate CV experiments across multiple scan rates—quickly and easily—so you can gain deeper insights without extra lab time.

6. Pulse Resistance (DCIR)

On the 6th day of Christmas, Ionworks simulated for me… Pulse Resistance! 🔋⚡

Curious about how efficiently your battery handles current flow? A Pulse Resistance (DCIR) test gives you the answer by measuring the battery’s internal resistance under real-world conditions. Since internal resistance drives heat generation, efficiency, and performance, it’s vital to understand how it behaves, especially under varying loads.

Here’s how it works: we apply a short current pulse to your battery and measure the resulting voltage drop. By repeating this at different states of charge (SOC) and C-rates, we gain a full picture of how internal resistance shifts based on operating conditions. These insights are indispensable for applications like EVs and consumer electronics, where optimizing performance at both high and low SOCs is key.

7. EIS

On the 7th day of Christmas Ionworks simulated for me... EIS! ⚡ 🌊 🔋

Electrochemical Impedance Spectroscopy (EIS) is essentially a frequency sweep through your battery’s inner workings. By applying a small AC signal across a wide frequency range, EIS uncovers the intricate interplay of processes that shape battery performance.

⬆️ At high frequencies: You’re looking at ohmic resistances—think electrolyte conductivity and current collector behavior.
➡️ In the mid-frequencies: Charge-transfer kinetics and double-layer effects dominate, offering insights into how quickly and efficiently reactions occur at the electrode surface.
⬇️ At low frequencies: Diffusion takes the spotlight, revealing how ions move through electrode materials and influence long-term capacity and stability.

What makes EIS truly powerful is its versatility. Whether you’re pinpointing degradation mechanisms, refining material choices, or fine-tuning equivalent circuit models, EIS distills complex electrochemical phenomena into actionable insights.

8. PITT

On the 8th day of Christmas, Ionworks simulated for me… a cycle of PITT ⚡▶️⏸️

The Potentiostatic Intermittent Titration Technique (PITT) is a sibling of GITT, applying a series of carefully controlled steps at changing SOCs. The difference is that PITT holds the voltage fixed for each step, monitoring current decay as the system approaches equilibrium. This enables precise analysis of lithium-ion kinetics and diffusion dynamics within electrode materials.

The trade-off? Each potential step requires significant equilibrium time, extending overall testing durations—and even more so if you’re testing under varying temperature conditions.

9. Peak Power

On the 9th day of Christmas, Ionworks simulated for me… a Peak Power Test 💥⚡📈

The Peak Power Test is a crucial assessment for determining the maximum power a battery can deliver in short bursts. By pushing the battery to its performance limits, this test reveals insights into how it handles high-demand conditions—an essential factor for applications requiring rapid energy delivery, especially for consumer electronics where apps can draw large amounts of power in short bursts.

Understanding your battery's peak power performance is key for avoiding brown-out at low SOCs and improving your customer's experience. Watch how we make it easy to visualize the peak power performance at different SOCs at durations.

10. Drive Cycle

On the 10th day of Christmas Ionworks simulated for me... a drive cycle experiment!

How does your battery perform in the real world, where loads are anything but constant? That’s the question a drive cycle experiment answers. By mimicking real-life power or current demands—like those experienced during EV acceleration, cruising, and braking—this test reveals how your battery handles dynamic operating conditions.

Drive cycle experiments are the key to understanding energy efficiency, thermal behavior, and capacity fade under realistic scenarios. From standardized profiles like WLTP or UDDS to custom cycles tailored to your application, this test evaluates performance across a wide range of speeds, accelerations, and regenerative braking events.

But it’s not just about vehicles. These experiments are equally valuable for renewable energy storage, robotics, or any system where fluctuating loads are the norm.