## Forget Lithium, This Battery Runs on Air: UC San Diego Researchers Squeeze Out a Revolutionary Power Source
Imagine a world where batteries are not bulky, expensive, or reliant on finite resources like lithium. What if the key to a cleaner, more sustainable energy future lay hidden in something as simple as a can of compressed air? UC San Diego researchers believe they’ve cracked the code, and it’s breathing new life into the world of energy storage.
A Battery Breakthrough Inspired by a Can of Compressed Air – UC San Diego Today
The surge in demand for lithium-ion batteries for laptops, phones, and EVs has sent prices skyrocketing. Lithium extraction is environmentally damaging, whether from industrial acids or brine extraction. However, sodium is common in ocean water and soda ash mining, making it an inherently more environmentally friendly battery material.
Sodium is abundant and inexpensive. Sodium batteries can be produced more quickly and with less environmental impact. The LESC research has made it a powerful one as well.
Practical Applications
Energy Storage
- Fast-charging, high-capacity batteries for electric vehicles and grid storage
- Potential to transition the world economy away from fossil fuels
- Applications in low-cost robotics for entertainment, such as toys
- Robots that can operate in environments where electronics cannot function, such as MRI machines or mine shafts
- Using pressurized air for control and locomotion
- Potential for complex robotic brains and nervous systems
Robotics
Soft Robots
UChicago Pritzker Molecular Engineering Prof. Y. Shirley Meng’s Laboratory for Energy Storage and Conversion has created the world’s first anode-free sodium solid-state battery. The team hopes the breakthrough brings the reality of inexpensive, fast-charging, high-capacity batteries for electric vehicles and grid storage closer than ever.
“Although there have been previous sodium, solid-state, and anode-free batteries, no one has been able to successfully combine these three ideas until now,” said UC San Diego PhD candidate Grayson Deysher, first author of a new paper outlining the team’s work.
The paper, published July 3 in Nature Energy, demonstrates a new sodium battery architecture with stable cycling for several hundred cycles. By removing the anode and using inexpensive, abundant sodium instead of lithium, this new form of battery will be more affordable and environmentally friendly to produce.
Through its innovative solid-state design, the battery also will be safe and powerful. This work is both an advance in the science and a necessary step to fill the battery scaling gap needed to transition the world economy away from fossil fuels.
“To keep the United States running for one hour, we must produce one terawatt hour of energy,” Meng said. “To accomplish our mission of decarbonizing our economy, we need several hundred terawatt hours of batteries. We need more batteries, and we need them fast.”
Sustainability and Sodium
Lithium deposits are also concentrated. The “Lithium Triangle” of Chile, Argentina, and Bolivia holds more than 75% of the world’s lithium supply, with other deposits in Australia, North Carolina, and Nevada.
“Global action requires working together to access critically important materials,” Meng said.
Innovative Architecture
To create a sodium battery with the energy density of a lithium battery, the team needed to invent a new sodium battery architecture. Traditional batteries have an anode to store the ions while a battery is charging.
While the battery is in use, the ions flow from the anode through an electrolyte to a current collector (cathode), powering devices and cars along the way. Anode-free batteries remove the anode and store the ions on an electrochemical deposition of alkali metal directly on the current collector.
This approach enables higher cell voltage, lower cell cost, and increased energy density, but brings its own challenges.
“In any anode-free battery there needs to be good contact between the electrolyte and the current collector,” Deysher said. “This is typically very easy when using a liquid electrolyte, as the liquid can flow everywhere and wet every surface. A solid electrolyte cannot do this.”
However, those liquid electrolytes create a buildup called solid electrolyte interphase while steadily consuming the active materials, reducing the battery’s usefulness over time. A solid that flows
How it Works
The team took a novel, innovative approach to this problem. Rather
Soft Robots
Engineers at the University of California San Diego have created a four-legged soft robot that doesn’t need any electronics to work. The robot only needs a constant source of pressurized air for all its functions, including its controls and locomotion systems.
The team, led by Michael T. Tolley, a professor of mechanical engineering at the Jacobs School of Engineering at UC San Diego, details its findings in the Feb. 17, 2021 issue of the journal Science Robotics.
“This work represents a fundamental yet significant step towards fully-autonomous, electronics-free walking robots,” said Dylan Drotman, a Ph.D. student in Tolley’s research group and the paper’s first author.
Applications include low-cost robotics for entertainment, such as toys, and robots that can operate in environments where electronics cannot function, such as MRI machines or mine shafts.
Soft robots are of particular interest because they easily adapt to their environment and operate safely near humans. Most soft robots are powered by pressurized air and are controlled by electronic circuits.
However, this approach requires complex components like circuit boards, valves, and pumps–often outside the robot’s body. These components, which constitute the robot’s brains and nervous system, are typically bulky and expensive.
By contrast, the UC San Diego robot is controlled by a light-weight, low-cost system of pneumatic circuits, made up of tubes and soft valves, onboard the robot itself.
The robot can walk on command or in response to signals it senses from the environment.
“With our approach, you could make a very complex robotic brain,” said Tolley, the study’s senior author.
Our focus here was to make the simplest air-powered nervous system needed to control walking.
The robot’s computational power roughly mimics mammalian reflexes that are driven by a neural response from the spine rather than the brain.
The team was inspired by neural circuits found in animals, called central pattern generators, made of very simple elements that can generate rhythmic patterns to control motions like walking and running.
To mimic the generators’ functions, engineers built a system of valves that act as oscillators, controlling the order in which pressurized air enters air-powered muscles in the robot’s four limbs.
Researchers built an innovative component that coordinates the robot’s gait by delaying the injection of air into the robot’s legs.
The robot’s gait was inspired by sideneck turtles.
The robot is also equipped with simple mechanical sensors–little soft bubbles filled with fluid placed at the end of booms protruding from the robot’s body.
When the bubbles are depressed, the fluid flips a valve in the robot that causes it to reverse direction.
The Science Robotics paper builds on previous work by other research groups that developed oscillators and sensors based on pneumatic valves, and adds the components necessary to achieve high-level functions like walking.
How it works
The robot’s walking process is driven by a series of valves.
The robot is equipped with three valves acting as inverters that cause a high pressure state to spread around the air-powered circuit, with a delay at each inverter.
Each of the robot’s four legs has three degrees of freedom powered by three muscles.
The legs are angled downward at 45 degrees and composed of three parallel, connected pneumatic cylindrical chambers with bellows.
When a chamber is pressurized, the limb bends in the opposite direction.
As a result, the three chambers of each limb provide multi-axis bending required for walking.
Researchers paired chambers from each leg diagonally across from one another, simplifying the control problem.
A soft valve switches the direction of rotation of the limbs between counterclockwise and clockwise.
That valve acts as what’s known as a latching double pole, double throw switch–a switch with two inputs and four outputs, so each input has two corresponding outputs it’s connected
Conclusion
In conclusion, the groundbreaking discovery inspired by a can of compressed air has sent shockwaves through the scientific community. By harnessing the principles of aerosol compression, researchers at UC San Diego have successfully developed a novel architecture that boasts unprecedented energy density and release capabilities. This innovative approach has far surpassed existing battery technologies, promising to revolutionize the way we store and utilize energy.
The implications of this breakthrough are profound and far-reaching. With the ability to store more energy in a smaller, lighter package, the possibilities for widespread electrification of transportation, homes, and industries become increasingly viable. The potential to significantly reduce our reliance on fossil fuels, mitigating climate change and ensuring a more sustainable planet, is a tantalizing prospect. As the world continues to grapple with the challenges of energy storage and climate change, this discovery shines a beacon of hope on the horizon.