Batteries made of lemons and oranges have been gracing grade school laboratories for years. In addition to fruit-based batteries, now you can make a battery using spit.

The new paper-based bacteria-powered battery can be activated with a single drop of saliva, generating enough power to power an LED light for around 20 minutes.

“The battery includes specialized bacterial cells, called exoelectrogens, which have the ability to harvest electrons externally to the outside electrode,” Seokheun Choi, co-author of the new study, tells Nexus Media. “For the long-term storage, the bacterial cells are freeze-dried until use. This battery can even be used in challenging environmental conditions like desert areas. All you need is an organic matter to rehydrate and activate the freeze-dried cells.”

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Lithium-ion batteries power a vast majority of the world’s portable electronics, from smartphones to laptops. A standard lithium-ion batteries utilizes a liquid as the electrolyte between two electrodes. However, the liquid electrolyte has the potential to lead to safety hazards. Researchers from MIT believe that by using a solid electrolyte, lithium-ion batteries could be safer and able to store more energy. However, most research in the area of all-solid-state lithium-ion batteries has faced significant barriers.

According to the team from MIT, a reason why research into solid electrolytes has been so challenging is due to incorrect interpretation of how these batteries fail.

This from MIT:

The problem, according to this study, is that researchers have been focusing on the wrong properties in their search for a solid electrolyte material. The prevailing idea was that the material’s firmness or squishiness (a property called shear modulus) determined whether dendrites could penetrate into the electrolyte. But the new analysis showed that it’s the smoothness of the surface that matters most. Microscopic nicks and scratches on the electrolyte’s surface can provide a toehold for the metallic deposits to begin to force their way in, the researchers found.

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In an effort to expand South Australia’s renewable energy supply, the state has looked to business magnate Elon Musk to build the world’s largest lithium-ion battery. The goal of the project is to deliver a grid-scale battery with the ability to stabilize intermittency issues in the area as well as reduce energy prices.

An energy grid is the central component of energy generation and usage. By changing the type of energy that powers that grid in moving from fossil fuels toward more renewable sources, the grid itself changes. Traditional electrical grids demand consistency, using fossil fuels to control production for demand. However, renewable sources such as wind and solar provide intermittency issues that traditional fossil fuels do not. Researchers must look at how we can deliver energy to the electrical grid when the sun goes down or the wind stops blowing. This is where energy storage systems, such as batteries, play a pivotal role.

In South Australia, Musk’s battery is intended to sustain 100 megawatts of power and store that energy for 129 megawatt hours. To put it in perspective, that is enough energy to power 30,000 homes and, according to Musk, will be three times as powerful as the world’s current largest lithium-ion battery.

Musk hopes to complete the project by December, stating that “It’s a fundamental efficiency improvement to the power grid, and it’s really quite necessary and quite obvious considering a renewable energy future.”

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Instead of batteries, a new cell phone harvests the few microwatts of power it needs from a different source: ambient radio signals or light.

Researchers were also able to make Skype calls using the battery-free phone, demonstrating that the prototype—made of commercial, off-the-shelf components—can receive and transmit speech and communicate with a base station.

“We’ve built what we believe is the first functioning cell phone that consumes almost zero power,” says Shyam Gollakota, an associate professor of computer science & engineering at the University of Washington and coauthor of the paper.

“To achieve the really, really low power consumption that you need to run a phone by harvesting energy from the environment, we had to fundamentally rethink how these devices are designed.”

Researchers eliminated a power-hungry step in most modern cellular transmissions—converting analog signals that convey sound into digital data that a phone can understand. This process consumes so much energy that it’s been impossible to design a phone that can rely on ambient power sources.

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In an effort to develop a more affordable, plentiful alternative to lithium-ion batteries, researchers from Purdue University are pursuing rechargeable potassium based batteries, demonstrating a way to derive carbon for battery electrodes from old tires.

“With the growth of rechargeable batteries for electronic devices, electric vehicles and power grid applications, there has been growing concern about the sustainability and cost of lithium,” says Vilas G. Pol, an associate professor in the Davidson School of Chemical Engineering at Purdue University and former member of ECS. “In the last decade, there has been rapid progress in the investigation of metal-ion batteries beyond lithium, such as sodium and potassium.”

Researchers in the field believe that potassium based batteries show potential for large-scale grid storage due to their low cost and the abundance of the element itself.

“The intermittent energy generated from solar and wind requires new energy storage systems for the grid,” Pol says. “However, the limited global availability of lithium resources and high cost of extraction hinder the application of lithium-ion batteries for such large-scale energy storage. This demands alternative energy storage devices that are based on earth-abundant elements.”

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A new development in electrolyte chemistry, led by ECS member Shirley Meng, is expanding lithium-ion battery performance, allowing devices to operate at temperatures as low as -60° Celsius.

Currently, lithium-ion batteries stop operating around -20° Celsius. By developing an electrolyte that allows the battery to operate at a high efficiency at a much colder temperature, researchers believe it could allow electric vehicles in cold climates to travel further on a single charge. Additionally, the technology could allow battery-powered devices, such as WiFi drones, to function in extreme cold conditions.

(MORE: Read ECS’s interview with Meng, “The Future of Batteries.”)

This from UC San Diego:

The new electrolytes also enable electrochemical capacitors to run as low as -80 degrees Celsius — their current low temperature limit is -40 degrees Celsius. While the technology enables extreme low temperature operation, high performance at room temperature is still maintained. The new electrolyte chemistry could also increase the energy density and improve the safety of lithium batteries and electrochemical capacitors.

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Unpiloted underwater vehicles (UUVs) are used for a wide array of tasks, including exploring ship wreckage, mapping the ocean floor, and military applications. Now, a team from MIT has developed an aluminum-water power system that will allow UUVs to become safer, more durable, and have ten times more range compared to UUVs powered by lithium-ion batteries.

“Everything people want to do underwater should get a lot easier,” says Ian Salmon Mckay, co-inventor of the device. “We’re off to conquer the oceans.”

The aluminum-water power system is a direct response to lithium-ion batteries, which have a limited energy density causing service ships to chaperone UUVs while at sea, recharging the batteries when necessary. Additionally, UUV lithium-ion batteries have to be encased in expensive metal pressure vessels, making the battery both short-lived and pricey for use in UUVs.

This from MIT:

In contrast, [Open Water Power’s] power system is safer, cheaper, and longer-lasting. It consists of a alloyed aluminum, a cathode alloyed with a combination of elements (primarily nickel), and an alkaline electrolyte that’s positioned between the electrodes.

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In an effort to increase security on airplanes, the U.S. government is considering expanding a ban on lithium-ion based devices from cabins of commercial flights, opting instead for passengers to transport laptops and other electronic devices in their checked luggage in the cargo department. However, statistics from the Federal Aviation Administration suggest that storing those devices in the cargo area could increase the risk of fires.

The FAA reports that batteries were responsible for nine airline fires in 2014. The number grew to 16 in 2015 and further to 31 in 2016. Most fires were able to be extinguished by passengers.
According to Homeland Security Secretary John Kelly, the U.S. government is considering expanding the ban to 71 additional airports.

(READ: “What’s Next for Batteries?” with Robert Kostecki.)

Mainstream concern regarding lithium-ion battery safety became widespread in 2016 when videos of hoverboards exploding began to emerge. Since then, news reports of smartphone and laptop batteries have emerged.

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In 2016, Solar Impulse 2 was the first solar-powered electrified aircraft to make a trip around the world. But that aircraft wasn’t the first to partake in electric flight, nor will it be the last.

Since the development of the battery-powered Militky MB-E1 in the early 1970s, there has been excitement surrounding the promise of an electric aircraft. However, many of the concepts being floated around by aerospace companies assume huge improvements in current battery technology.

The problem? According to a recently published article in Wired, current battery technology does not offer the power-to-weight ratio needed to make battery-powered planes feasible.

But battery technology has taken leaps over the past few years. Energy storage devices are become more efficient and lighter simultaneously. But how long will it take to be able to pack enough energy into a device while remaining light enough to glide through the sky?

“There’s already been a lot of progress,” Venkat Srinivasan, battery expert with Argonne National Lab, told Wired. “It’s not the same ballpark as Moore’s law progress because it’s chemistry, not electronics, but it’s still very good.”

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The electric vehicle market continues to build momentum every year, with consumers around the world growing more interested. But in order for EVs to pave the way for the future of transportation, more efficient, longer-lasting batteries will need to be developed.

That’s where ECS member Jeff Dahn, leader of Tesla’s researcher partnership through his Dalhousie University research group, comes in. Recently, Dahn and his team unveiled new chemistry that could increase battery lifecycle at high voltages without significant degradation.

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