Quantum Batteries – Powering the Future at the Speed of Light?

Why the need for new batteries?

As our world races towards an ever-greater reliance upon electric vehicles and renewable energy, the once ingenious lithium batteries is beginning to show its limitations. Within the United States alone, battery storage capacity grew fivefold between 2021 and 2024, placing enormous pressure on existing infrastructure to deliver more—faster, safer, and more sustainable. 

Just as quantum computing is revolutionising communication and computing, it may soon do the same for energy. First introduced in 2013, quantum batteries are slowly being turned from concept to reality by combining physics and bold engineering. But how do they work? What are their advantages? And is it even possible?

Lithium Batteries

To fully understand how quantum batteries work, it is crucial to know how a normal lithium battery works.

In essence, a lithium battery is made up of an anode and a cathode (positively and negatively charged plates),where lithium ions are transferred through a liquid called an electrolyte, creating a current. The electrolyte allows ions to flow efficiently whilst preventing the flow of electrons. The cathodes are kept apart using a thin separator sheet to ensure that there is no short-circuiting. To charge a lithium battery, a voltage is applied across the terminals, causing the ions to move from the cathode to the anode. These ions are stored in the anode until they are used.

How do quantum batteries work, and what are their advantages?

Now that we know how a basic lithium battery works, we can move on to the quantum battery. At its core, a quantum battery is a system that stores energy using quantum mechanics rather than traditional electrochemistry. Instead of relying on chemical reactions between electrodes and electrolytes, quantum batteries use qubits and the phenomena of superposition, entanglement, and superabsorption. 

Superposition

Quantum batteries are not made up of anodes, cathodes, and electrolytes, but instead are composed of quantum dots, which make up qubits. Unlike a regular bit (the basic unit of information), which can only exist in one state at a time (1 or 0), a qubit can exist in any superposition between 0 and 1. This allows for a far greater number of possible states, resulting in faster charging times. 100 classical bits can represent one of 2¹⁰⁰ possible configurations at any time, but 100 qubits can exist in a superposition of all 2¹⁰⁰ configurations simultaneously. This then means that qubits can store multiple values at the same time, allowing them to gain a huge speed advantage over classical bits.

Entanglement and Superabsorbtion

Quantum entanglement is another advantage of these new batteries. When qubits are ‘entangled’, the state of one qubit instantly determines the state of the other. Interestingly, even if one qubit is entangled with another on the other side of the universe, if we were to change the state of one, the other would also change the state. Another key feature is that multiple qubits can become ‘entangled’ with one another. This allows all qubits to charge simultaneously by changing the state of just one. Entanglement is achieved by applying special quantum gates (building blocks of quantum circuits) to create a direct link between two qubits. To entangle two qubits, we start with both in the ∣0⟩∣0⟩ state. Applying a Hadamard (H) gate to the first qubit creates a superposition of ∣0⟩∣0⟩ and ∣1⟩∣1⟩. Then, applying a CNOT gate with the first qubit as the control and the second as the target entangles the qubits. The resulting state is:

This entangled state means that measuring one qubit immediately determines the state of the other, even if they are far apart. The qubits are now linked as part of a single quantum system.

Having the entangled qubits also gives rise to a quantum phenomenon called superabsorption, where the system can absorb more energy than would be possible in classical physics. When qubits are entangled, their combined interaction with light can lead to potentially enhanced absorption. Instead of absorbing the sum of both parts, the entangled qubits can store more energy than is possible. This would lead to increased energy storage over regular non-entangled qubits, resulting in batteries that can store much more energy. Furthermore, it would also lead to a reduction in charging times as the entangled qubits would be able to absorb more energy in a shorter time.

Current Research and Limitations

If these new batteries offer such incredible benefits, then why have they not been made yet? The main reason for this is because quantum systems are extremely fragile; they lose their quantum properties through interaction with the environment, a problem called decoherence. To create a battery, you would need a system that not only maintains quantum effects like entanglement and superposition but also interacts with the outside world to deliver energy, which is difficult to balance. We also lack practical materials that can support stable quantum states at large scales and room temperature, as most quantum experiments still require very cold, highly controlled environments. On top of that, designing a battery that stores and releases energy quantum mechanically presents entirely new engineering challenges. As classical batteries are still improving steadily, there is also less immediate commercial pressure to invest heavily in quantum battery development. Finally, the theory of quantum thermodynamics is still being developed, so we don’t fully understand all the principles needed to make quantum batteries practical. That said, there have been some small-scale experiments showing that quantum effects can speed up charging, but they are still at a very early stage.

A notable example of a small-scale quantum battery is the prototype developed by researchers from the Politecnico di Milano and Italy's National Research Council (CNR). The device consists of a microcavity enclosing a molecular dye called Lumogen-F Orange. This is achieved by an active layer of organic molecules, placed between two dielectric mirrors to form the microcavity. As a result, each molecule within the setup can live in a quantum state of superposition, the same way that a qubit does. This experiment is important as it is one of the first to display coherence. This coherence allows the units to act cooperatively, resulting in a charging power that increases faster than the battery size—a phenomenon termed "superextensive charging." 

In conclusion, quantum batteries offer a variety of benefits that could well be of extreme importance soon. Whilst this technology is still in its infancy, there have already been many promising prototypes that have helped to turn theoretics into reality. As researchers and engineers overcome current limitations, quantum batteries could become game-changers in how we power everything from electric vehicles to homes, which could change the world as we know it.