Tech Briefs Magazine - February 2024 - 36

Power & Energy
to study when lithium was deposited, in
real time and in 3D using X-ray tomographic
microscopy. Although many researchers
have wanted to study lithium
metal in a working cell, no one had been
able to do so as far as the team knew. If
they succeeded, it would be a major step
forward, compared with analyzing images
after a cell has been cycled.
" It was magical when we saw with our
own eyes that it worked on the first attempt, "
Matic said. " When we observed the
lithium creating big structures, like huge
needles, it was almost like being in a lunar
landing project. We've been wanting to observe
the inner workings of batteries in real
time for so long. And now we can. "
Next, the research team aims to test
the technique on other battery concepts,
hoping that the necessary imaging technology
will be available closer to home,
for example at the Swedish MAX IV lab,
a national research facility for advanced
X-ray experiments.
" We're looking forward to developing
this method to take faster measurements
at higher resolution to see more
detailed microstructures formed early
on in the deposition process, " Matic
says. " This is a key piece of the puzzle to
be able to use lithium metal batteries
on a large scale and make them safe. A
lot of research teams and companies
are looking at the lithium metal concept
for their future prototypes. "
For more information, contact
Mia Halleröd Palmgren at mia.
hallerodpalmgren@chalmers.se; +1 46721-513-512.
Space
Solar Power Demonstrator Wirelessly Transmits
Power in Space
Wireless power transfer was recently demonstrated by MAPLE, one of three key technologies
being tested by the Space Solar Power Demonstrator.
California Institute of Technology, Pasadena, CA
W
ireless power transfer was recently
demonstrated by MAPLE - Microwave
Array for Power-transfer Low-orbit Experiment
- one of three key technologies
being tested by the Space Solar Power
Demonstrator (SSPD-1), the first spaceborne
prototype from Caltech's Space Solar
Power Project (SSPP), which aims to
harvest solar power in space and transmit it
to the Earth's surface.
MAPLE consists of an array of flexible
lightweight microwave power transmitters
driven by custom electronic chips that were
built using low-cost silicon technologies. It
uses the array of transmitters to beam the
energy to desired locations. For SSPP to be
feasible, energy transmission arrays will
need to be lightweight to minimize the
amount of fuel needed to send them to
space, flexible so they can fold up into a
package that can be transported in a rocket,
and a low-cost technology overall.
" Through the experiments we have
run so far, we received confirmation that
MAPLE can transmit power successfully
to receivers in space, " said SSPP Co-Director
and Professor Ali Hajimiri, who
led the team that developed MAPLE.
" We have also been able to program the
array to direct its energy toward Earth,
which we detected here at Caltech. We
had, of course, tested it on Earth, but
now we know that it can survive the trip
to space and operate there. "
" To the best of our knowledge, no one
has ever demonstrated wireless energy
transfer in space even with expensive rigid
structures. We are doing it with flexible
lightweight structures and with our own integrated
circuits, " said Hajimiri.
Beyond a demonstration that the power
transmitters could survive the launch and
space flight, and still function, the experiment
has provided useful feedback to SSPP
engineers.
Space solar power provides a way to tap
into the practically unlimited supply of solar
energy in outer space, where the energy
is constantly available without being subjected
to the cycles of day and night, seasons,
and cloud cover - potentially yielding
eight times more power than solar
panels at any location on Earth.
When fully realized, SSPP will deploy a
constellation of modular spacecraft that
collect sunlight, transform it into electricity,
then convert it to microwaves that will be
transmitted wirelessly over long distances
to wherever it is needed - including locations
that currently have no access to reliable
power.
" In the same way that the internet democratized
access to information, we hope
that wireless energy transfer democratizes
access to energy, " said Hajimiri. " No energy
transmission infrastructure will be needed
on the ground to receive this power.
That means we can send energy to remote
regions and areas devastated by war or natural
disaster. "
Individual SSPP units will fold up into
packages about 1 m³ in volume and then
unfurl into flat squares about 50 m per
side, with solar cells on one side facing the
sun and wireless power transmitters on the
other side facing Earth.
SSPD has two main experiments besides
MAPLE: DOLCE (Deployable on-Orbit ultraLight
Composite
Experiment) and
Photo from space of the interior of MAPLE, with the transmission array to the right and the receivers
to the left. (Image: SSPP)
36
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ALBA, a collection of 32 different types of
photovoltaic cells to enable an assessment
of the types of cells that are the most effective
in the punishing environment of space.
For more information, contact Kathy
Svitil at ksvitil@caltech.edu; 626-3958022.
Tech
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