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research and development
Batteries taking charge
T
he ability to affordably store
energy in large quantities for both
residential and grid applications
is set to redefine energy consumption,
production and grid operation. With
batteries set to become a requisite part of
residential power systems, it should come as
no surprise that development in the energy
storage sector has gone into overdrive.
Lithium-ion (Li-Ion) batteries are the
current forerunners in this booming
industry, and with their high energy density
and compact footprint it’s easy to see
why. Indeed, a host of lithium alternatives
to Tesla’s now famous Powerwall are
beginning to come out of the woodwork.
Advancements in lithium battery
technology are also progressing with US
body, the National Institute of Standards
and Technology (NIST), University of
Arizona and Seoul National University
jointly developing an inexpensive method
for fabricating Lithium-Sulphur batteries.
Through a process coined ‘inverse
vulcanisation’ researchers have produced
a stable plasticised sulphur cathode that is
cheap (sulphur is a petroleum bi-product)
and easy to produce. The resulting battery
was touted to retain over 50% of its
capacity after 500 cycles.
Their ability to deliver in power intensive
situations means lithium batteries can
perform well in a range of applications,
but the alkali metal’s inherent instability
and the battery’s consequential
incendiary potential will always dissuade a
considerable portion of the market.
To fill this gap there is a host of emerging
battery chemistries and technologies that
have the potential to deliver some very
stiff competition to lithium and make
the energy storage market extremely
competitive in the near future.
Redflow’s ZBM
A relatively small, modular zinc-bromine
flow battery that can also be containerised
to form large scale storage systems
has been developed by Brisbane-based
company Redflow. The batteries, or
zinc-bromide modules (ZBMs), range
from 8–11kWh and have a footprint of
just 0.34m².
Flow batteries operate by continuously
pumping an electrolyte between a
storage compartment and a reaction
chamber containing the electrodes. This
action means flow batteries contain
more moving parts than most other
batteries and while this can be seen
as a disadvantage, the separation of
compartments also allows for the
replacement of the electrode stack while
retaining the battery’s other elements.
The nominal 48V batteries have a
100% depth of discharge and operate
at near linear voltage and current levels
across all charge states, making them well
The fervour surrounding
energy storage devices
is driving significant
developments in battery
chemistry and technology,
causing a diverse
marketplace to emerge.
Jacob Harris explains.
This article has been reproduced with permission from ELECTRICAL Connection magazine, SUMMER 2015.
Connection Magazines does not endorse any manufacturer, product or service nor does it provide any assurances of product or service performance.
ELECTRICAL Connection

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suited to energy applications as opposed
to power applications.
While the company’s key target market
is telecommunications base transceiver
sites, Redflow also focuses on transmission
and distribution deferral over smart grids
and micro grids, renewables integration, on
and off grid remote power and residential
energy storage.
The batteries can be kept at low or zero
state of charge for long periods of time
without degradation and can use their full
capacity for deep day-in day-out cycling.
ZBMs can also be stored uncharged and
have an indefinite shelf life.
“We have a longer base life than Li-Ion
and when factoring in the ZBM’s capacity
for 100% depth of discharge and its
indefinite shelf life, Redflow’s battery
life can be seen to significantly increase.
Our ZBM3 (11kWh) has an expected
life of more than 44,000kWh, and this
can be extended further with a stack
replacement,” says Redflow’s marketing
manager Sciobhan Leahy.
ZBMs are built from a commonly
sourced plastic and contain no rare earth
elements. Their electrolyte (a water
based solution of zinc-bromide salt) is fire
retardant and because of the separation
of the stack and tank there is no chance of
thermal runaway.
ZBMs are managed by an on-board
Module Management System (MMS) that
controls battery operations while providing
access to battery status, real-time data,
event logs, warnings and alarms. This
allows the battery to self-manage and
protect against potential risks.
Ambri’s liquid metal battery
American company Ambri is in the
process of fine tuning a liquid metal
battery. Originally developed by MIT
professor Don Sadoway, the technology is
touted to fundamentally change the way
power grids are operated. Unfortunately,
dates for the first commercial sales have
recently been pushed back due to an
issue with one of the battery’s seals, but
the company is still progressing with
development – albeit at a reduced pace.
The battery’s cells are made of three
simple components, a salt electrolyte
which separates two metal (electrode)
layers of magnesium (Mg) and antimony
(Sb). Because of their different densities
these components naturally form three
layers when in a liquid state. As the
battery discharges, Mg electrons move
across the electrolyte to form an Mg-Sb
alloy, when the battery is recharged the
metals separate again and return to their
original compositions.
Because the battery is all liquid, the
electrodes will not degrade in the same
way as their solid counterparts. This means
the battery could potentially last many
years without losing much of its storage
capacity. The batteries are also incredibly
scalable and can range in size from 100kWh
to hundreds of mWhs.
The cells are housed in steel containers
and are assembled in systems using
basic components such as steel racking.
Because of this, Ambri’s manufacturing
strategy involves steel workers on a
production line that is similar to an
aluminium smelter. This relatively
simple manufacturing process and
the technology’s use of cheap, earth
abundant materials, means the batteries
promise to be extremely affordable to
build and maintain.
Aquion Energy’s aqueous
hybrid ion battery
Commercial shipments of Aquion
Energy’s AHI batteries began in mid-
2014 and are rapidly increasing because,
according to Aquion’s VP of product
management Matthew Maroon,
they satisfy several unmet market
requirements.
Being saltwater batteries that use no
heavy metals, they are a clean, non-
toxic energy storage solution based
on abundant, low-cost materials. AHI
batteries are modular and scalable for
various power/energy ratio applications
up to mW scale and are easily
manufactured, providing economical,
long-duration storage for high-energy
applications such as renewable energy
storage and time shifting.
“AHI batteries are optimised for
daily deep cycling (defined as 4 to 20+
hour charge and discharge cycles) for
residential solar. Being adept at long
duration cycling and because they’re
not damaged by long stands at partial
state of charge, they are high performing
under solar cycling profiles and are the
cleanest and safest storage solution
available. In fact, Aquion batteries are
the only ones that are Cradle-to-Cradle
certified and we’ve found that their
inherent safety really resonates with
customers,” says Matthew.
As the energy storage market grows,
we can expect new innovations in battery
technology to come to light increasingly
frequently. There is room for multiple
players in battery manufacturing as
different battery chemistries will play a role
in meeting the needs of different customer
types and applications.
Development in the energy
storage sector has gone
into overdrive.
This article has been reproduced with permission from ELECTRICAL Connection magazine, SUMMER 2015.
Connection Magazines does not endorse any manufacturer, product or service nor does it provide any assurances of product or service performance.
ELECTRICAL Connection