Conventional and fuel cells. Differences and operation

07/05/2026

The online cell simulations on this page will help you to better understand how conventional batteries, also called electric cells, and fuel cells work and what are the differences between them.

This Thematic Unit is part of our Chemistry collection

Catalytic Electrode

Conductive surface that facilitates the redox reaction of external gases without being consumed or degraded during the process.

Conventional Battery

Device that stores its reactants internally and ceases to supply current when chemical equilibrium is reached.

Energy Density

Amount of energy stored per unit of mass or volume, a critical parameter for comparing the efficiency of different battery systems.

Fuel Cell

Type of galvanic cell designed to operate continuously by the external flow of reactants toward the electrodes.

Galvanic Cell

Electrochemical device that transforms chemical energy into electrical energy through spontaneous electron transfer reactions.

Membrane Electrolyte

Selective barrier that allows the passage of specific ions between electrodes while blocking the direct passage of electrons and gases.

Operating Autonomy

Duration during which the system can generate energy, limited in conventional batteries by their reactants and in fuel cells by the external supply.

Storage Capacity

Total amount of electrical charge (usually in Ah) that a battery can supply based on the mass of its internal reactants.

Conventional cells and fuel cells

Conventional batteries, or electric cells, and fuel cells are two technologies that allow electricity to be generated from chemical processes. While they have some similarities, they also have important differences in their operation, applications and advantages. Each has its own advantages and challenges, and their use is determined by the specific application. In general, electric cells are more common in portable and electronic applications, while fuel cells are more suitable for power generation and long-distance transportation systems.

Conventional or electric cells

Conventional cells or electric cells, also known as batteries, are devices that convert the chemical energy stored inside them into electrical energy. They consist of two electrodes, one positive and one negative, and an electrolyte. When the electrodes are connected to an electrical circuit, electrons flow from the negative to the positive electrode through the circuit, generating electricity. Electric batteries are very common in electronic devices such as cell phones, laptops and cameras.

Fuel cell

Fuel cells, on the other hand, convert the chemical energy of a reaction between a fuel and an oxidant into electrical energy. Fuel cells consist of two electrodes, an anode and a cathode, separated by an electrolyte. The fuel, which can be hydrogen, methane or even alcohol, is fed to the anode and the oxidant, usually oxygen from the air, is fed to the cathode. The chemical reaction between the fuel and oxidant produces electrons that flow from the anode to the cathode through an electrical circuit, generating electricity and water as a by-product.

Comparison between battery types

Fuel cells have some advantages over electric cells, such as higher efficiency and lower pollutant emissions. In addition, they can be powered by a wide variety of fuels, such as hydrogen, methane, ethanol, natural gas and biofuels. This gives them great versatility in terms of their use, from portable applications to power generation systems in large facilities.

However, fuel cells also present some challenges. Although they are more efficient than electric cells, their production cost is still high. In addition, they require fuel storage and supply systems, which can be complicated and expensive. Moreover, the production of hydrogen, one of the most common fuels for fuel cells, still relies heavily on fossil fuels, which limits its use as a renewable energy source.

Catalytic Electrode

Conductive surface that facilitates the redox reaction of external gases without being consumed or degraded during the process.

Conventional Battery

Device that stores its reactants internally and ceases to supply current when chemical equilibrium is reached.

Energy Density

Amount of energy stored per unit of mass or volume, a critical parameter for comparing the efficiency of different battery systems.

Fuel Cell

Type of galvanic cell designed to operate continuously by the external flow of reactants toward the electrodes.

Galvanic Cell

Electrochemical device that transforms chemical energy into electrical energy through spontaneous electron transfer reactions.

Membrane Electrolyte

Selective barrier that allows the passage of specific ions between electrodes while blocking the direct passage of electrons and gases.

Operating Autonomy

Duration during which the system can generate energy, limited in conventional batteries by their reactants and in fuel cells by the external supply.

Storage Capacity

Total amount of electrical charge (usually in Ah) that a battery can supply based on the mass of its internal reactants.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Cell simulations

Conventional cell

A conventional battery is a device that generates electricity through a chemical reaction. This animation represents Volta’s and Daniel’s electric cells.

Fuel cell

A fuel cell is a device that converts chemical energy into electricity through a reaction between oxygen and hydrogen that results in water.

Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Joseph Louis Gay-Lussac

1778

–

1850

Joseph Louis Gay-Lussac formulated fundamental gas laws on the relationship between volume, temperature, and pressure, also studying gas mixtures and chemical reactions in air

“Chemistry is the key to understanding nature”

Michael Faraday

1791

–

1867

Michael Faraday discovered electromagnetic induction, conducted pioneering experiments in optics (Faraday effect), and established fundamental principles of electrochemistry.

“Nothing is too wonderful to be true”

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“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Robert Boyle

1627

–

1691

Robert Boyle formulated the first quantitative law of gases, showing the relationship between pressure and volume, laying foundations of modern chemistry and fluid mechanics

“Air is as necessary to life as food”

Gilbert Newton Lewis

1875

–

1946

Gilbert Lewis formulated the chemical bond theory, introduced electron pairs, and contributed to acid-base theory

“Atoms build nature as bricks build a building”

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The Physics of Electronic Polymers (PEP)

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Electrochemistry

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Test your knowledge

What fundamental aspects define how a conventional electrochemical cell operates compared to a fuel cell?

A conventional electrochemical cell relies on chemical substances stored inside it. These substances react spontaneously and release electrical energy until the reactants are consumed. Once that happens, the cell can no longer produce electricity. A fuel cell, however, does not store its reactants internally. Instead, it continuously receives fuel and oxidant from external sources, allowing it to generate electricity as long as the supply is maintained. This continuous‑flow design makes fuel cells suitable for long‑duration applications and often results in cleaner and more efficient energy conversion. The distinction between “stored reactants” and “externally supplied reactants” is what fundamentally separates the two technologies in both behavior and practical use.

How do the properties of the fuel and oxidant influence the performance and applicability of a fuel cell?

The efficiency and practicality of a fuel cell depend heavily on the type of fuel it uses and how easily that fuel reacts with the oxidant. Hydrogen enables highly efficient and clean reactions, but storing and producing it can be technically challenging. Other fuels—such as methane, ethanol, or natural gas—are easier to obtain and integrate into existing infrastructures, though they may require more complex processing and can generate additional by‑products. This diversity of possible fuels makes fuel cells adaptable to many contexts, from portable electronics to large‑scale power systems. At the same time, it introduces constraints related to cost, purity requirements, and the environmental impact of producing the fuel itself.

Why do electrons always leave from the negative electrode in a battery instead of the positive one?

Because the negative electrode is where the reaction that releases electrons takes place. That electrode ends up with an excess of electrons, and they naturally move through the external circuit toward the positive electrode, where they can be accepted. The battery isn’t “pulling” electrons from the negative side; it’s the chemistry inside that creates an imbalance, and the electrons simply follow the path that lets them flow and complete the reaction.

What would happen if a fuel cell stopped receiving fuel for a moment? Would it still work?

It would stop producing electricity almost immediately. A fuel cell depends on a constant supply of fuel and oxidant because the reaction only occurs while both are present. If the flow stops, the reaction stops, and so does the electrical output. It’s similar to a car engine running out of fuel: nothing is broken, but the system has nothing to work with until the supply is restored.

Why are fuel cells considered “clean” if producing hydrogen can still cause pollution?

Because the fuel cell itself doesn’t generate pollutants while it’s running—it typically produces only electricity and water. The environmental impact depends on how the hydrogen is produced. If it comes from fossil fuels, there are emissions associated with that process, but not with the fuel cell’s operation. If the hydrogen is produced using renewable energy, the entire system can be almost emission‑free. That’s why people talk about “green hydrogen” as the ideal scenario.