Tech Briefs Magazine - February 2022 - BT-20

Schematic illustration of an integrated solar flow battery. A solar cell is hooked up to tanks of
chemicals that can store electricity for later use. (Photo: Wenjie Li)
dramatically increased. The materials can
also increase the efficiency of traditional
silicon solar cells by capturing more energy
from the Sun. Yet silicon remains key for
making a stable device that can withstand
the chemicals in a flow battery.
The team fabricated the perovskite-silicon
solar cells with an additional protection
layer on the silicon surface. To predict
the ideal voltage at which the flow batteries
should run, the team developed a new
theoretical modeling method that allowed
them to select a pair of chemicals in the
flow battery that would operate at the ideal
voltage based on the characteristics of the
solar cell, maximizing efficiency. The chemicals
are organic compounds, not expensive
metals as in traditional flow batteries, and
are dissolved in a benign water solution of
table salt rather than strong acids.
The integrated solar flow battery contains
both a solar cell and chemicals to generate,
store, and redeliver renewable electricity from
the Sun in one device. (Photo: Wenjie Li)
The resulting device maintained a high
efficiency over hundreds of hours and
hundreds of charge-discharge cycles
while retaining most of its capacity. That
lifespan was several times longer than
earlier devices.
      
 
Fast-Charging, Long-Running, Bendable
Supercapacitor
This technology has potential as a portable power supply in several applications, including electric vehicles,
cellphones, and wearable technology.
University College London, United Kingdom
A
20
new bendable supercapacitor made
from graphene has been developed
that charges quickly and safely stores
a record-high level of energy for use over a
long period. The technology overcomes the
issue faced by high-powered, fast-charging
supercapacitors: they usually cannot hold a
large amount of energy in a small space.
The new supercapacitor is extremely
promising for next-generation energy storage
technology as either a replacement for
current battery technology, or for use
alongside it, to provide the user with more
power. It was designed with materials that
give it a high power density and a high
energy density. It also can bend to 180
degrees without affecting performance and
doesn't use a liquid electrolyte, which minimizes
risk of explosion and makes it suitable
for integrating into phones or wearable
electronics.
The bendable supercapacitor. (Photo: University
College of London)
A graphene electrode material with
pores can be changed in size to store the
charge more efficiently. This tuning maximizes
the energy density of the supercapacitor
to 88.1 Wh/L (Watt-hour per liter).
Similar fast-charging commercial technology
has a relatively poor energy density
of 5-8 Wh/L and traditional slowcharging;
long-running lead-acid batteries
used in electric vehicles typically
have 50-90 Wh/L. Power density is two
Battery & Electrification Technology, February 2022

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Tech Briefs Magazine - February 2022

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