Automotive Engineering - March 2023 - BET29

Also key to the battery's design is its
novel, nano-engineering that allows the
battery to overcome limitations of previous
aqueous batteries, such as slow
charging times and poor stability.
Yang is an expert in developing materials
for renewable energy devices
such as batteries with improved safety.
The UCF-designed battery
is fast
charging, reaching full charge in three
minutes, compared to the hours it takes
Li-ion batteries.
Previous aqueous battery designs have
suffered from low energy output, instability,
the growth of harmful metallic structures
called dendrites on the negative
electrode and corrosion.
By using saltwater as the battery's
liquid electrolyte, the UCF researchers
were able to use naturally occurring
metal ions found in the saltwater, such
as sodium, potassium, calcium, and magnesium,
to create a dual-cation battery
that stores more energy. This implementation
allowed them to overcome the
sluggishness of previous single-cation
aqueous battery designs.
To solve problems with instability, dendrite
growth and corrosion, the researchers
engineered a forest-like 3D zinc-copper
anode containing a thin zinc-oxide
protective layer on top.
The novel, nano-engineered surface,
which looks like a birds-eye-view of a
forest, allows the researchers to precisely
control electrochemical reactions,
thereby increasing the battery's stability
and quick charging ability. Furthermore,
the zinc-oxide layer prevented dendritic
growth of zinc, which was confirmed
using optical microscopy.
" These batteries using the novel materials
developed in my lab will remain safe
even if they are used improperly or are
flooded in saltwater, " Yang said. " Our work
can help improve electric vehicle technology
and continue to advance it as reliable
and safe form of travel. "
For more information, contact Andrea
Adkins at Andrea.Adkins@ucf.edu;
407-823-0138.
Improving Accuracy of Battery Charge Measurement
High-precision monitoring of charge/discharge current over a wide range of EV batteries using diamond
quantum sensors.
Tokyo Institute of Technology, Japan
T
he issue of battery usage inefficiency
in electric vehicles (EVs) resulting
from an inaccurate battery charge
measurement may finally get resolved,
thanks to a diamond quantum sensor
prototype developed in the MEXT Q-LEAP
Flagship project with researchers from
Tokyo Tech and Yazaki Corporation. The
sensor can measure currents in a wide
range as well as detect milliampere-level
currents in a noisy environment, improving
the detection accuracy from 10 percent
to within 1 percent.
The popularity of EVs as an environmentally
friendly alternative to conventional
gasoline vehicles has been on the
rise. This has led to research efforts directed
toward developing high-efficiency
EV batteries. However, a major inefficiency
in EVs results from inaccurate estimations
of the battery charge. The charge
state of an EV battery is measured based
on the current output of the battery. This
provides an estimate of the remaining
driving range of the vehicles.
Typically, the battery currents in EVs
can reach hundreds of amperes. However,
commercial sensors that can detect such
currents cannot measure small changes
in the current at milliampere levels. This
Battery & Electrification Technology, March 2023
leads to an ambiguity of around 10 percent
in the battery charge estimation.
What this means is that the driving
range of EVs could be extended by 10
percent. This, in turn, would reduce inefficient
battery usage.
Now, a team of researchers from Japan,
led by Professor Mutsuko Hatano from
Tokyo Institute of Technology (Tokyo
Tech), has come up with a solution. In
their study published in Scientific
Reports the team has reported a diamond
quantum sensor-based detection
technique that can estimate the battery
charge within 1 percent accuracy while
measuring high currents typical of EVs.
In their work, the team made a prototype
sensor using two diamond quantum
sensors that were placed on either
side of the busbar (electrical junction for
incoming and outgoing currents) in the
car. They then used a technique called
" differential detection " to eliminate the
common noise detected by both the
sensors and retain only the actual signal.
This, in turn, enabled them to detect a
small current of 10 mA amid background
environmental noise.
Next, the team used a mixed analog-digital
control of the frequencies
generated by two microwave generators
to trace the magnetic resonance
frequencies of the quantum sensor over
a bandwidth of 1 gigahertz. This allowed
for a large dynamic range (ratio
of largest to smallest current detected)
of ±1000 A. Moreover, a wide operating
temperature range of −40 to +85 °C
was confirmed to cover general vehicular
applications.
Finally, the team tested this prototype
for Worldwide Harmonized Light
Vehicles Test Cycle (WLTC) driving, a
standard test for energy consumption
in EVs. The sensor accurately traced the
charge/discharge current from -50 A to
130 A and demonstrated the battery
charge estimation accuracy within 1
percent.
According to Professor Hatano, " In creasing
battery usage efficiency by 10 percent
would reduce battery weight by 10
percent, which will reduce 3.5 percent
running energy and 5 percent production
energy of 20 million new EVs in 2030 WW.
This, in turn, corresponds to a 0.2 percent
reduction in CO2
emissions in 2030 WW
transportation field. "
For more information, contact Mutsuko
Hatano at hatano.m.ab@m.titech.ac.jp.
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