Coin Cell Battery Guide: Types, Sizes, Chemistry, Safety, and Battery R&D Uses

Coin cell batteries are small, round batteries used in watches, car key fobs, computer motherboards, medical devices, calculators, sensors, remote controls, and many other compact electronic products. Although many coin cells look similar from the outside, their internal chemistry, voltage, size, discharge behavior, and safety requirements can be very different.

This coin cell battery guide explains how coin cell batteries are named, how common chemistries such as CR, SR, LR, and LIR differ, how to select the correct replacement battery, and why coin cells are also important in lithium battery research.

At Flux Battery, coin cells are especially relevant from a research perspective. We supply laboratory coin cell components such as CR2032 coin cell cases, spacers, springs, separator discs, disc cutters, and crimping tools for battery R&D, university laboratories, and material evaluation workflows. Flux Battery’s coin cell preparation products are designed to help researchers standardize electrode cutting, pressure, handling, and cell assembly for repeatable test results. 

Quick Answer: What Is a Coin Cell Battery?

A coin cell battery is a small, round, flat battery with a diameter larger than its height. In daily use, people often call these batteries “button batteries” or “coin batteries.” They are commonly used in low-power electronic devices because they are compact, lightweight, and able to provide stable power for long periods.

However, not all coin cells are the same. A CR2032, SR44, LR44, and LIR2032 may all be small round batteries, but they use different chemistries and have different voltages. Choosing the wrong one can cause poor performance, unstable contact, device failure, leakage risk, or overvoltage damage.

1. How Coin Cell Battery Codes Work

Most coin cell battery codes use letters and numbers to describe the battery chemistry and size.

A common example is:

CR2032

This code can be understood as:

CR = lithium manganese dioxide chemistry
20 = 20.0 mm diameter
32 = 3.2 mm thickness

So a CR2032 is a lithium manganese dioxide coin cell with a 20.0 mm diameter and 3.2 mm thickness. Energizer’s CR2032 datasheet lists the cell as a lithium coin battery with the chemical system lithium/manganese dioxide, designation IEC-CR2032, nominal voltage of 3.0V, and typical dimensions of 20.0mm diameter and 3.2mm height.

This is why CR2032 and CR2025 are not identical, even though both are 20mm in diameter. CR2032 is 3.2mm thick, while CR2025 is 2.5mm thick. In some devices, using a thinner cell may create poor contact pressure, intermittent power loss, or unstable operation.

2. Main Coin Cell Battery Chemistries

Coin cell batteries are classified mainly by their electrochemical system. The chemistry determines the nominal voltage, discharge curve, shelf life, leakage behavior, and suitable application.

CR Series: Lithium Manganese Dioxide Coin Cells

CR-series coin cells are lithium manganese dioxide primary batteries. They are non-rechargeable and typically have a nominal voltage of 3.0V.

Common examples include:

CR2016
CR2025
CR2032
CR2430
CR2450

CR-series cells are widely used in:

• Computer motherboard CMOS backup
• Car key fobs
• Remote controls
• Medical devices
• Sensors
• Memory backup systems
• Low-power electronics

The CR2032 is one of the most common lithium coin cells. Its advantages include high energy density, long shelf life, and low self-discharge. Energizer’s CR2032 datasheet lists typical self-discharge at approximately 1% per year, which explains why this chemistry is widely used in long-standby applications.

SR Series: Silver Oxide Button Cells

SR-series cells are silver oxide batteries. They are usually used in precision devices that require a stable voltage output.

Common examples include:

SR44
SR626
SR621
SR920

Silver oxide cells normally have a nominal voltage of around 1.55V. Energizer’s SR44 / 357 datasheet identifies the chemistry as silver oxide, designation IEC-SR44, with a nominal voltage of 1.55V. 

Silver oxide batteries are commonly used in:

• Watches
• Medical instruments
• Precision measurement tools
• Digital calipers
• Cameras
• Small electronic instruments

Their key advantage is voltage stability. Maxell describes silver oxide batteries as having a stable operating voltage up to the end of discharge, which makes them suitable for devices where voltage consistency matters.

LR / AG Series: Alkaline Button Cells

LR-series coin cells are alkaline manganese dioxide batteries. They are usually lower-cost and are often used in devices that do not require an extremely stable voltage output.

Common examples include:

LR44
LR41
LR1130
AG13
AG10

AG names are often older or commercial naming conventions, while LR names are more commonly used in IEC-style technical documentation. For example, LR44 is also commonly sold as A76 or AG13.

Energizer’s A76 datasheet identifies the cell as manganese dioxide chemistry, designated IEC-LR44, with a nominal voltage of 1.5V.

LR / alkaline button cells are commonly used in:

• Small toys
• LED lights
• Simple calculators
• Low-cost electronic devices
• Basic household electronics

They are cost-effective, but their voltage is generally less stable than silver oxide cells. Therefore, they may not be ideal for precision timing or measurement devices.

LIR Series: Rechargeable Lithium-Ion Coin Cells

LIR-series coin cells are rechargeable lithium-ion coin cells. A common example is:

LIR2032

This is where many users make a dangerous mistake.

A LIR2032 may have the same physical size as a CR2032, but it is not the same battery. A CR2032 is a 3.0V non-rechargeable lithium manganese dioxide cell, while a LIR2032 is typically a 3.6V or 3.7V rechargeable lithium-ion coin cell. A LIR2032 datasheet lists a nominal voltage of 3.7V and a charging voltage of 4.20V.

This means a LIR2032 should not be used as a direct replacement for CR2032 unless the device is specifically designed for rechargeable lithium-ion coin cells.

The physical size may match, but the electrical system may not.

3. CR2032 vs CR2025: Why Thickness Matters

CR2032 and CR2025 are often confused because they share the same diameter.

CR2032 = 20.0 mm diameter × 3.2 mm thickness
CR2025 = 20.0 mm diameter × 2.5 mm thickness

The 0.7mm difference may look small, but in a compact battery holder, it matters.

If the battery compartment is designed for CR2032 and a CR2025 is inserted, the thinner cell may not press firmly against the contacts. This can cause:

• Intermittent power loss
• Increased contact resistance
• Device reset
• Unstable voltage supply
• Failure under vibration

In engineering applications, battery selection is not only about voltage. Mechanical fit, contact pressure, thickness, and holder design are equally important.

4. Selection Rules: How to Choose the Right Coin Cell

When replacing or specifying a coin cell battery, follow these rules.

Rule 1: Match the Size

Always match the full battery code, not just the diameter.

For example:

CR2032 is not always replaceable with CR2025.

Even if the diameter is the same, the thickness and contact pressure may be different.

Rule 2: Match the Chemistry

Different chemistries have different voltage and discharge behavior.

CR = lithium manganese dioxide, usually 3.0V
SR = silver oxide, usually 1.55V
LR = alkaline manganese dioxide, usually 1.5V
LIR = rechargeable lithium-ion, usually 3.6V–3.7V

Never assume that two coin cells are interchangeable just because they look similar.

Rule 3: Match the Voltage

Voltage mismatch can damage sensitive electronics.

The most important warning is:

Do not replace CR2032 with LIR2032 unless the device is designed for LIR cells.

A fully charged LIR2032 can reach 4.2V, while many CR2032-powered devices are designed around a 3V system. That difference can overstress circuits.

Rule 4: Consider the Discharge Curve

For precision timing, measurement, or medical devices, stable voltage matters. Silver oxide cells are often preferred in applications where the voltage curve must remain flat for most of the discharge life.

Rule 5: Consider Storage Life and Leakage Risk

For long-standby devices such as BIOS backup, car key fobs, and sensors, lithium CR-series cells are often preferred because they have a long shelf life and low self-discharge. CR2032 datasheets commonly highlight low self-discharge and long service capability under low-drain conditions.

5. Coin Cell Safety: Small Battery, Serious Risk

Coin cell batteries can be dangerous if swallowed, especially by children.

The main risk is not simply “choking.” If a button or coin cell becomes lodged in the esophagus, it can create an electrical current through body fluids. This can generate hydroxide at the battery surface and cause severe chemical burns.

The CDC warns that button batteries, especially coin-sized batteries with a diameter of 20mm or larger, can lodge in the esophagus and lead to serious complications or death. The CDC also notes that a battery lodged in the esophagus can cause serious burns in as little as 2 hours.

Energizer’s CR2032 datasheet also states that swallowing may lead to serious injury or death in as little as 2 hours due to chemical burns and potential esophageal perforation.

For safety:

• Keep coin cells away from children.
• Store new and used batteries in child-resistant containers.
• Do not leave loose batteries on desks, drawers, bags, or floors.
• Secure battery compartments with screws or child-resistant designs.
• Dispose of used batteries promptly and responsibly.
• Seek immediate medical help if ingestion is suspected.

6. Coin Cells in Battery Research: Not the Same as Consumer Button Batteries

In consumer electronics, a coin cell is a small power source.

In battery research, a coin cell is often a test platform.

Researchers use coin cell formats such as CR2032 to evaluate new cathode materials, anode materials, electrolytes, separators, additives, current collectors, and electrode formulations.

A research coin cell usually includes:

• Coin cell case
• Cathode case
• Anode case
• Gasket
• Spring
• Spacer
• Cathode electrode disc
• Separator disc
• Anode electrode disc
• Electrolyte

Flux Battery supplies CR20XX coin cell case sets for CR2032, CR2025, CR2016, and CR2430 formats. The SS304 coin cell case product page describes these cases as standard laboratory components for assembling coin cells for battery research and material evaluation.

Flux Battery also supplies CR2032 SS316L coin cell case sets that include a cathode case, an anode case, a wave spring, and a spacer, with a pre-installed PP gasket on the anode case.

7. Why Coin Cell Components Matter in R&D

In battery research, data repeatability is critical. If the cell assembly process is inconsistent, researchers may misinterpret the electrochemical performance of the active material.

Small differences can affect test results, including:

• Electrode disc diameter
• Separator thickness
• Electrolyte amount
• Stack pressure
• Spacer thickness
• Spring force
• Sealing quality
• Contact resistance
• Case material
• Crimping consistency

This is why laboratory coin cell components are not just “accessories.” They influence the reliability of the test cell.

Flux Battery’s coin cell separator discs are designed for laboratory coin cell assembly and are compatible with common CR2032, CR2025, and CR2016 coin cell cases. These separator discs provide electrical insulation between the cathode and anode while allowing ion transport through the electrolyte. 

For researchers working on lithium-ion, sodium-ion, lithium-sulfur, or other electrochemical systems, consistent coin-cell components help reduce experimental noise and improve comparisons between test groups.

8. Consumer Coin Cells vs Research Coin Cell Cases

It is important to distinguish between a commercial coin cell battery and a laboratory coin cell case.

A commercial CR2032 battery is already a sealed primary battery. It is used directly in electronic devices.

A laboratory CR2032 coin cell case is an empty metal housing used to assemble experimental cells. Researchers place electrodes, separator, electrolyte, spring, spacer, and gasket into the case, then seal it using a coin cell crimper.

Flux Battery’s coin cell preparation collection includes hydraulic coin cell crimpers, disc cutters, rolling presses, coating tools, disassembly machines, spacers, springs, and coin cell cases. These tools support controlled laboratory workflows for CR-series coin cells. 

So when researchers talk about “CR2032 coin cell testing,” they usually mean an experimental cell assembled in a CR2032-sized case, not a consumer CR2032 battery purchased for a remote control.

9. Practical Coin Cell Selection Checklist

Before selecting a coin cell battery or coin cell case, check the following:

For Consumer Devices

1. Match the exact battery code.
2. Confirm voltage compatibility.
3. Confirm chemistry.
4. Check thickness and diameter.
5. Avoid replacing primary lithium cells with rechargeable lithium-ion cells unless allowed.
6. Use high-quality batteries from reliable manufacturers.
7. Keep all button and coin cells away from children.

For Battery Research

1. Select the correct case format: CR2032, CR2025, CR2016, or CR2430.
2. Choose case material: SS304, SS316L, Al-clad, or specialized formats.
3. Match spacer and spring dimensions to the electrode stack.
4. Use separator discs with consistent diameter and thickness.
5. Control electrolyte volume.
6. Maintain consistent crimping pressure.
7. Record every component batch for traceability.

Match the exact battery type and keep coin cells away from children.