When most people think about electric vehicle (EV) battery development, they picture large battery packs, cooling systems, and high-voltage cells destined for production vehicles. In reality, many EV battery technologies begin life in a laboratory coin cell small enough to fit in the palm of a hand.
Coin cells allow researchers to evaluate a battery chemistry before advancing it to larger cell formats.
Before engineers commit time and resources to larger-format cells, modules, and battery packs, they typically evaluate new materials and chemistries using coin cells. The format offers a relatively inexpensive and repeatable way to study how a battery behaves long before it reaches automotive scale.
“Almost every cell that ends up in a vehicle started as a coin cell on a bench. This is where you learn whether a chemistry is worth pursuing, long before it ever reaches a car,” explains Hang Lau, principal product manager, Thermodynamic Properties, Waters Materials Sciences Division (formerly TA Instruments).
Why start with coin cells?
Developing a new battery chemistry involves evaluating a wide range of variables. Researchers may be testing a new cathode material, anode material, electrolyte formulation, separator, or additive package. Building large-format cells for every iteration would be costly and time-consuming.
Coin cells allow engineers to quickly compare different material combinations while minimizing material consumption and manufacturing complexity.
“With coin cells, you can compare different battery chemistries side by side and see which one is actually moving in the right direction,” says Lau. That kind of controlled comparison is hard to get any other way.”
A single development program may involve hundreds or even thousands of coin cells before a promising chemistry advances to larger prototypes.
Coin-cell testing is the starting point in other fields too. It shows up in battery energy storage systems (BESS), aerospace, robotics, and consumer electronics.
So, what can be learned from coin cells? Despite their small size, coin cells can reveal a significant amount of information about battery behavior.
Researchers commonly use coin cells to evaluate:
- Capacity and energy-storage performance
- Charge-discharge efficiency
- Cycle life and degradation trends
- Electrochemical behavior
- Thermal stability
- Gas generation
- Early indicators of thermal runaway
These measurements help engineers determine whether a particular chemistry warrants further development.
Thermal characterization is particularly important as battery developers seek to improve safety while increasing energy density. Understanding how a cell behaves under elevated temperatures can help identify potential failure mechanisms long before a design reaches final cell format or vehicle-level testing.
The challenge of scaling results
While coin cells are valuable development tools, they do not provide a complete picture of how a battery will perform in an EV.
Large-format automotive cells introduce additional challenges related to thermal management, manufacturing consistency, mechanical stresses, current distribution, and cell-to-cell interactions. Module and pack-level testing remains essential before a battery can be qualified for vehicle use.
“A coin cell will not tell you everything about a finished pack, but the questions you answer at this stage shape every decision that follows,” she shares. “The more you can measure from a single cell, the fewer surprises you meet later.”
As a result, battery development typically follows a progression from coin cells to larger prototype cells, then to modules and eventually full battery packs.
Each stage answers a different set of engineering questions.
Linking thermal, gas, and electrochemical behavior
This coin-cell testing system measures heat flow from experimental EV battery cells, helping researchers identify thermal instability before a chemistry advances to larger automotive cell formats.
One area receiving increased attention is the relationship between thermal behavior, gas generation, and electrochemical performance.
Traditionally, engineers relied on multiple instruments and separate experiments to collect these data sets. New testing platforms are seeking to combine these measurements into a single workflow, allowing researchers to correlate thermal events with electrochemical behavior and evolved gases from the same cell.
The goal is to identify safety concerns and failure mechanisms earlier in the development process, when design changes are less costly and easier to implement.
For EV battery developers, these early insights can help guide material selection, improve safety evaluation, and reduce development risk before a chemistry advances to larger and more expensive cell formats.
The next generation of EV batteries may ultimately power vehicles with hundreds of miles of range, but many of those technologies will begin their journey inside a coin cell only a few centimeters wide.
“The batteries that will carry people hundreds of miles are being shaped right now, at the scale of a coin cell. Get the measurement right there, and that confidence follows the design all the way to the vehicle,” Lau says.
Filed Under: Batteries, FAQs, Test And Measurement, Testing and Safety