A Japanese start-up plans to test an experimental battery on the Moon

A type of battery still under development on Earth could move to the Moon as early as 2021 aboard a lunar commercial lander. The Japanese start-up ispace plans to be the first to test a solid-state battery on the surface of the moon, hoping that this emerging technology can help solve the problem of storing energy out of the world .

Countries and societies like ispace are trying to send back both robots and people to the moon. They will need energy to power their rovers, their homes and other electronic equipment once there. Solar energy is an option, but areas of the lunar surface remain without sun rays for weeks. During sunny days, temperatures drop and solar panels receive no light. Finding a battery capable of withstanding extreme temperature variations while still allowing efficient energy storage could be a great benefit for lunar exploration.

Semiconductor batteries could be a promising solution. This is a very popular version of traditional lithium-ion batteries, found in iPhones, Teslas, and basically anything that has a rechargeable battery. Lithium-ion batteries rely on a flammable liquid called electrolyte to help move charged particles called ions from one side to the other of the battery. Unfortunately, this liquid can cause problems even here on our planet. At high temperatures, electrolytes can ignite and can, for example, detonate phones. At low temperatures, the liquid freezes into a solid and the battery turns off completely.

In solid-state batteries, the electrolyte is a solid material carefully designed to help ions move, according to a PhD student studying semiconductor batteries at the Swiss Federal Laboratories for Science and Technology. materials. Instead of having liquid surrounding everything, the different parts are stacked in solid layers, which also makes the battery more compact.

Image: Will Joel /The edge

Semiconductor batteries are supposed to hold more energy and charge faster than a conventional li-ion battery. In theory, they could also better survive the dramatic changes in Moon temperature from 260 ° C (127 ° C) to 260 ° F at minus 180 ° C in the shade. The battery does not ignite because of the heat and the electrolyte is already designed to be a solid in which the ions can pass. While the intense cold slows down the charge of solid-state batteries, they have at least the potential to survive in space, whereas a conventional lithium-ion battery would never succeed.

The proposed Moon battery will be manufactured by the Japanese company NGK Spark Plug. The companies have not yet finalized the exact specifications of the Moon battery, but have announced that they will have a ceramic electrolyte. (Ceramics is one of the most popular options for solid electrolytes because it is pretty stable.) The plan is to perform very basic tests, just to see if the battery can survive and keep a charge in the vacuum. space on the Moon. Hopefully the experience will "expand the possibilities" of batteries in the space, said a spokesman for NGK Spark Plug.

Wanting to use solid-state batteries in space is not new, according to Rao Surampudi, head of NASA's Jet Propulsion Laboratory's Electrical Systems Program Office and author of several reports on energy storage. in the space. "We started working on solid-state batteries in 1991," he says. "We are still working on it."

The main challenge is that the life cycle of solid-state batteries (or the number of times a battery recharges before it dies) is incredibly limited. It will not be very useful in space, where things have to last a very long time. "You can replace the battery of your car or your cell phone, but you can not go back and replace the battery of a spaceship," Surampudi adds.

The poor cycle life is also one of the main reasons why solid-state batteries have not taken off on Earth either. Many companies try to market them, but you still can not buy a solid-state battery for your phone or electric vehicle. At present, we can only manufacture small batteries in the solid state and most only last 18 months. They are also extremely expensive to manufacture, much less. "It was promised that solid-state batteries would come on the market in the next two to three years, and investors are increasingly looking forward to the progress of the solid," commented Ian McClenny, an analyst at Navigant Research, specialist of battery research, said The edge. Realistically, McClenny does not believe that solid-state batteries will be a commercial option until the early to mid-2020s.

Surampudi is also skeptical. Semiconductor battery technology is not yet very mature, he said, and it will probably take five to ten years to refine it sufficiently for a more practical application. That's why we "spend $ 100 million" to invest in more research, he adds.

Meanwhile is It is also possible to design traditional lithium-ion batteries that will work well in space. Many lithium-ion batteries are used onboard the International Space Station and are designed so that any unforeseen explosion does not injure astronauts or compromise safety. And it is the traditional lithium-ion (although very well designed) that has powered the recently deceased Mars Rover Opportunity vehicle for 15 years, according to Surampudi, which has contributed to the development of this technology. His team created special thermal management systems to help batteries deal with heat and cold, and tested them for three years in extreme temperatures.

That's not to say that lithium-ion is the ultimate goal. "It's time to replace the lithium-ion," says Surampudi. "This country has to invest and we have to find the next best battery. But the development of the battery is not an easy task, because the simplest solutions were put in place a long time ago. "

We'll see what happens when the NGK solid-state battery goes into space, and it will take at least a few years before that happens. ispace plans to launch its first mission – a lunar orbiter – aboard a SpaceX Falcon 9 rocket by 2020. If successful, the company will launch a lander and rover combo (which will carry the battery) to another Falcon. 9 in 2021..

In the end, ispace's long-term vision is to create a prosperous and sustainable community on the moon, where people live and interact with robotic spacecraft. For that to be possible, it will be necessary to find intelligent solutions of storage of energy. Semiconductor batteries could be part of that future, but it may take some time before they materialize.