The modern battery has come a long way in its 224-year history. In place of Alessandro Volta’s stacks of metal discs and brine-soaked cloth, we now have graham cracker-sized batteries that can go days before needing a recharge.
But what is the cap of devices on the market right now? What technical challenges must be overcome to break this ceiling, and when will these obstacles be overcome? What is the future of energy storage?
Several scientists around the world are working on an answer: battery technology that uses the laws of quantum physics, not classical physics, to maintain a charge. It’s a long, long way, but Rome wasn’t built in a day—and it certainly wasn’t powered in a day.
The main, beloved battery
A battery is a piece of technology that uses chemical reactions to produce electrical energy. Household batteries produce electrical energy by the flow of electrons through a circuit. Various battery cells have been developed over the centuries; Benjamin Franklin is believed to have coined the term “electric battery” in a 1749 letterwhich he ended with an amusing riff on the wonders of electricity:
Putin should be killed for our dinners by electrocution; and roasted by the electric jack, before a fire kindled by the electrified bottle; when the health of all the famous electricians in England, France, and Germany must be drunk in electrified armor, under the discharge of the guns from the electric battery.
Fast forward through several different battery cells, mostly named after the scientists who developed them using chemical reactions of various acids and metals, and in 1859 we had the lead-acid battery – the first with the capacity to be recharged by reversing the current through the system. In the late 20th century, the lithium-ion battery came into vogue and has essentially remained popular ever since, using various permutations of lithium combined with other metals and phosphates. But throughout the history of the modern battery, the basic principle of the chemical reaction that produces electricity has not changed.
Ok, forget the battery. What the hell is “quantum”?
Let’s take a quick overview of quantum physics in general terms. Particles in quantum states operate by a completely different set of rules than everything you see around you, from the water in the clouds to the blood vessels flowing in your veins. Particles enter quantum states under extreme conditions: very low temperatures and in a vacuum. Under these conditions, particles can act as multiple things at once, making them useful for doing things like complex mathematical operations (as a quantum computer does) and checking whether time travel (in a sense) is possible.
Quantum systems can also be imagined entanglementa phenomenon by which two or more quantum particles determine the characteristics of each other. In quantum computers, the atoms in the array carry the information needed for the given operation, just like the bits in an ordinary computer. These atoms are quantum bits or qubits.
But quantum operations are delicate. The moment any value in the quantum system is certain, the operation breaks down. Then the entire system—for example, atoms in an array—returns to the classical state.
Quantum states can exist for a long time. Take time crystals, first state of matter proposed in 2012 which earlier this year physicists showed could stay at least 40 minutes, about 10 million times longer than other known crystals. These crystals are far from quantum batteries, but they demonstrate how transient some quantum systems tend to be—an important problem that must be solved if we are ever to rely on such power modes.
So how do the rules of quantum mechanics apply to a battery, the technology that allows you to continue reading this article and perhaps more after recharging it?
Quantum batteries as it currently stands
Like normal batteries, quantum batteries – as they are presented – store energy. But that’s where the similarities end. Unlike chemical reactions that simultaneously charge and drain a battery’s stored energy, quantum batteries are powered by quantum entanglement, or behavior that more closely binds the battery and its source.
“Quantum batteries are made up of many quantum cells that act like one big quantum battery,” said Ju-Yeon Gyhm, a quantum researcher at Seoul National University in South Korea, in an email to Gizmodo. “The challenge is how to preserve the quantum properties for a long time.”
Since the same properties apply to quantum batteries as quantum computers, one major technical challenge must be resolved to see the technology become a reality outside of research settings: Physicists must figure out how to maintain quantum systems in their delicate states beyond the most carefully managed research settings. A superconductor at room temperature would be such a grail, but these days the only one people who claim such discovery they had their work to do debunked within months.
“Equilibrium thermodynamics sets no limits on how quickly energy is transformed into heat and work,” wrote a team of five scientists at a recent colloquium on quantum batteries, currently host on the arXiv preprint server. “Therefore, it seems natural to look for thermodynamic quantum advantages in quantum systems that are out of equilibrium.”
The group noted that quantum entanglement is related to how quickly energy can be stored in many-body quantum systems, a discovery that has spurred research into quantum systems as energy storage devices.
In 2018, a team modeled Dicke’s quantum battery, the first proposed to exist in a solid-state architecture, and in 2022team tested a basic framework for a quantum battery in a laboratory setting using a target, mirrors and laser light.
Recent experiments reveal the problem
Late last year, a team of quantum researchers proposed a system by which quantum batteries could be charged in an indefinite causal order, or ICO. Their findings –published in Physical examination letters— claims that an ICO billing system can outperform conventional billing protocols.
“Roughly speaking, ICO can be used to construct quantum processes that are not possible in standard quantum theory, where the causal order must be determined or fixed,” said Yuanbo Chen, a researcher at the University of Tokyo and lead author of the study, in an email to Gizmodo. “This flexibility allows for a greater variety of quantum processes, some of which may exhibit advantageous and interesting properties.”
“We have seen huge gains in both energy stored in the system and thermal efficiency. And somewhat counterintuitively, we found the surprising interaction effect that is the opposite of what you might expect: a lower-powered charger can provide higher energies with greater efficiency than a comparably higher-powered charger using same device,” Chen said at the time.
Different experimental setups of quantum battery systems – both proposed and realized – mean that there are different avenues for innovation in the design of such a futuristic technology. Last month, a team from the University of Gdansk and the University of Calgary suggested a quantum battery charging system that maximizes the amount of energy stored in the battery while minimizing the amount of energy dissipated (or lost) in the charging process. Part of the team’s redesign is that the quantum battery and its charger are connected to the same reservoir, creating a perturbation-like pattern that improves the efficiency of energy transfer between the two. The team estimates that the battery can store four times more energy through the new charging process than using a conventional charger.
“Quantum batteries act more like a wave, where the molecules or atoms act in unison, whereas in conventional batteries the molecules or atoms act more like individual particles,” said James Quach, a quantum researcher at the University of Adelaide in Australia, in an email to Gizmodo. “This collective behavior is the basis of the super-extensive charging properties of quantum batteries, where it takes less time to charge quantum batteries with larger capacities.”
In 2022, a team led by Quach tested the basic framework of a quantum battery by placing a molecular dye called Lumogen-F orange in a small cavity and pulsing light at it to see how it stored the energy transmitted by photons of light. The team found that the system loaded remarkably quickly, and that larger systems should generally load faster.
“Currently, it takes femto- to picoseconds to charge a quantum battery that stores about a microjoule of energy for nano- to milliseconds,” Quach said. “Although that doesn’t sound like a long time, the storage time is actually more than a million times longer than the charging time. In comparison, this would be equivalent to a conventional battery that takes minutes to charge, and can hold that charge for hundreds of years.
Like reported by A new scientist, some physicists theorize that the charging time of a quantum battery is inversely proportional to the number of qubits in the system; in other words, the bigger the battery, the faster it charges.
So…when can I get a quantum battery?
Research into quantum batteries is gaining ground, but is still in its infancy. While their promise is remarkable, what the final design of the technology will be remains an open question. Commercialization? It’s just a twinkle in the eye of the most business minded physicist right now.
The main problem remains to make quantum systems stay in a quantum state when scaled up. Quach believes that quantum batteries could be used as a mobile power source in phones and cars, but many quantum systems currently need very cold, silent conditions to remain so (as an aside, Quach’s experimental setup from 2022 .operates at room temperature). Not to demoralize you, dear reader, but nuclear fusion it’s probably closer to reality than the quantum batteries in our devices.
Although many skeptical reporters are reluctant to admit it, I’d be happy to eat my words. The only thing better than being right is making the world a better place by being wrong. Quantum batteries could be charged faster and more efficiently than classical devices and could be integrated with nascent quantum technologies that are used for high simulations and measurements. A fully working quantum battery has yet to be demonstrated, but according to a recent colloquium, such technology could revolutionize the way we harvest, deliver and control energy. Given that humanity is obvious dependence on electricityenergy storage could use a quantum leap.
More ▼: Physicists made a quantum computer work by blowing it up with the Fibonacci sequence
