are an essential part of every modern day person's life, and
are used by most people in the developed world on a daily
basis. The most common rechargeable batteries are known as lead
acid, NiCd, NiMH and lithium-ion or Li-ion.
Lead acid, with its
heavy physical weight, environmental toxicity, low specific
energy and limited cycle count, still holds a solid position
for starter and standby batteries, as no other system can
currently beat its cheap price and ruggedness.
| Rechargeable battery family
The Li-ion family receives the most
attention and is slowly replacing its nickel-based predecessors
which dominated the battery world until the 1990s. And
while the lead acid family may still be the cheapest on the
market up-front, the cost of ownership for a Li-ion battery
versus a lead acid one could tip the scales in lithium's
engineering, maintenance, installation and disposal cost
benefits may outweigh the lead-acid argument in many cases, as
well as its improved safety, reliability, and reduced
between Li-ion batteries
batteries have a vast array of chemistries
with end use depending on weight, lifespan, safety performance,
specific energy and power, cost and the overall power supply
performance. Development of these batteries is driven by end
uses, as well as the cost of raw materials.
The Li-ion system was
conceived as far back as the 1970s, but, like all cutting-edge
technology, did not gain traction right away. By the 1990s,
Li-ion was being taken up rapidly.
The term 'lithium-ion'
refers to a family of batteries in which ions move from the
negative electrode (anode) to the positive electrode (cathode)
during discharge and back again when being charged.
|Lithium battery performance (Source:
Sealed Performance Batteries)
Li-ion batteries are broken down into two
sub-types; lithium iron phosphate (LFP) and metal oxides
-nickel manganese cobalt (NMC), nickel cobalt aluminum (NCA),
cobalt (LCO), manganese (LMO) - and lithium titanite (LTO).
With the exception of lithium titanite (LTO), it is usually the
material composition of the cathode which gives its name to the
Li-ion type, with the anode most commonly made of
A speaker at this
year's IDC Technologies Lithium Battery Conference, Ryan
Hammond, an electrical engineer by trade and now director of
Sealed Performance Batteries, stressed that Li-ion batteries
are a "family of batteries".
In his talk, which
focused on how the world is to replace lead-acid battery
systems with Li-ion, Hammond said that "the important thing to
note is that the best battery technology depends on the
The NMC has become one
of the most widely used lithium technologies in the world. The
battery is gaining popularity in home energy storage systems,
such as the 7kWh Tesla Powerwall, the LG Chem equivalent and
the Leclance Apollion Cube.
battery is relatively safe with a 210°C thermal runaway
threshold, as well having a good charge time and low cost of
The NMC battery
additionally has a relatively high number of charge cycles,
defined as the number of times the battery can be discharged
and charged again before the maximum capacity of the battery is
reduced to 80-85% of its initial capacity. In NMCs this can be
anywhere between 3,000 and 8,000 cycles.
Another advantage of
NMC batteries is that their composition can be modified to
produce high specific power while maintaining low specific
energy. This characteristic has already given rise to NMC use
in electric vehicles (EVs) such as the BMW i3 and the Nissan
Specific energy refers
to the battery's gravimetric energy density and defines battery
capacity in terms of weight (Wh/kg). Similarly, energy density
(as opposed to gravimetric energy density, or specific energy),
reflects volume in litres.
Specific power, a
separate term, can be defined as gravimetric power density and
is indicative of loading capability. To make these terms
simpler, the relationship can be represented by water flowing
from a water bottle into a glass, seen below.
| Specific energy in Li-ion
batteries (Source: Battery
The water in the bottle represents specific energy
(capacity); the spout pouring the water governs specific power
(loading). Here, the bottle of water has high energy density
(or specific energy) and lower specific power.
A battery can have high
specific energy but poor specific power as is the case with the
alkaline battery, or low specific energy but high specific
power as with the
Moving on to NCAs,
which are closely related to NMC batteries in terms of
characteristics but differ in that they are slightly less safe
with a thermal runaway point of 150°C, in addition to being
Thermal runaway occurs
when a battery is overheated and results in heat spreading from
the inside to the outside of the battery, occasionally
resulting in explosions and fires. This has already become a
major concern for airlines carrying Li-ion
On the plus side, NCAs
have a higher energy density than NMCs, while still maintaining
a higher specific power. This is important, because it means
that like NMCs, NCAs are well suited to EVs, and are now known
for their use in Tesla cars. NCA battery packs are the most
expensive part of a Tesla, and provide power with a 435km
Lithium iron phosphate,
or LiFePO4, is a well-known lithium technology due
to its wide use and suitability for a range of applications.
The battery is recognised for its moderate specific energy,
excellent safety characteristics, good number of cycles
(5,000-8,000), great charge/discharge capabilities, as well as
its moderate price point.
make the LiFePO4 battery a strong option for
residential storage as per their use in the Alpha ESS battery
and the Enphase battery system.
The cell voltage of
3.2V/cell also makes it the lithium technology of choice for
sealed lead acid replacement in a number of key
There are a number of
reasons why LiFePO4 is the most suitable lithium
technology for replacement of sealed lead acid batteries (SLA).
These include its similar voltage, similar charge voltage and
its all-round good performance for multiple
batteries are also one of the safest forms of the lithium
technologies when considering temperature and abuse such as
overcharge and discharge, short circuit and penetration, as
they have the highest thermal runaway point of any of the
lithium batteries mentioned, have a long shelf life (they
experience a slow rate of capacity loss, meaning that they can
sit on a shelf for up to 12 months without requiring a refresh
charge) and have a high cycle life, making them very cost
batteries are also environmentally friendly due to their
chemistry components. When considering this against the
environmental risk posed by lead acid chemistry against the
direction in which companies are heading in terms of
environmental care and sustainability, LiFePO4 makes
a compelling case.
>650 @ 50% Discharge
>7000 @ 50% Discharge
Up to 6 months
Up to 12 months
8 to 12 hours
1 to 3 hours
50% to 60%
80% to 100%
3 to 5 years
60% to 90%
Source: Ryan Hammond, Sealed
although LiFePO4 batteries are becoming a very
viable option for SLA replacement, they still have a long way
to go, as demonstrated by a 2015 Avicenne Energy study
demonstrating SLA's current 90% market share.
LiFePO4 shows exemplary safety characteristics,
talks at this year's IDC Technologies Lithium Battery
Conference were quick to point out that a battery monitoring
system (or BMS) is still necessary in every case.
require a BMS for safety and to protect the cells from damage
in scenarios such as over-temperature, over-charge, cell
imbalance and short circuit.
In addition to home
energy storage, LiFePO4 batteries are suited to
mobility vehicles, recreational vehicles, caravans and campers
for their high cycle applications, medical devices, RC devices
for their quick-charge capability, as well as boats and gold
carts for their weight.
Atlas Copco announced
this year the first 100% battery driven underground loader,
something that the company says offers potential for greater
production, reduced costs and zero emissions. The system also
allows for lower heat emission, reducing cost of mine
ventilation or refrigeration.
The Scooptram ST7
Battery will first be introduced in Canada and the US and will
be gradually rolled out across the globe.
loader (Source: Atlas Copco)
LTO as a battery cell is distinguished by the fact it is not
the material located in the cathode, rather it replaces the
graphite in the anode of a typical Li-ion battery. The cathode
is made of graphite and resembles the architecture of a typical
LTO batteries have a
nominal cell voltage of 2.40V, can be fast-charged and deliver
a high discharge current of 10 times the rated capacity. The
cycle count is said to be higher than that of a regular Li-ion
of 15,000 cycles or more, depending on the depth of discharge,
operation temperature and charge/discharge rates. Li-titanate
is safe, has excellent low-temperature discharge
characteristics and obtains a capacity of 80 percent at
LTO batteries can
operate in conditions of up to around 60°C, thus a thermal
runaway event is significantly less likely to occur. LTO cells
can also be re-operated after an event of an over-discharge,
unlike conventional graphite-based Li-Ion cells. This feature
enables the user to operate the battery cells under extreme
environmental and operational conditions.
The two characteristics
which work against LTO are the low energy density at
approximately 63Wh/kg and its relative high cost compared to
the other options, however these are offset by the very high
specific power and extremely high cycle life.
Despite its benefits
LTO technology is relatively unknown. The cell's
characteristics make it an ideal solution for applications that
require the battery to be cycled highly or where there is a
short amount of power required in a short time, such as grid
applications and electric buses. It can also to be charged at a
rapid rate, again an advantage for heavy EVs.
Applications such as
grid stabilisation, frequency shifting and peak saving, as well
as industrial type EVs (those which can handle the heavy
weight) such as buses, ferries and trucks are ideally suited to
LTO. The Leclanche Ti-Box is an example of an energy storage
system that currently used LTO technology.
Like LTO, lithium
sulphur batteries use a lithium anode, this time with a
carbon/sulphur cathode. The battery is known for its extremely
high energy density, doubling that of NCA energy density. Sony,
which also commercialised the first Li-ion battery, plans to
introduce lithium sulfur batteries to the market in
Li-ion battery chemistries
Two more popular Li-ion
battery chemistries exist, including manganese oxide (LMO), and
lithium cobalt oxide (LCO) chemistries. LMOs have a specific
energy between that of a LFP and NMC cell, and the LCO has a
specific energy equal to the NMC.
LCO cells are the more
commonly known cell type, having a high capacity that is used
in handheld devices such as cell phones, laptops and cameras,
while LMOs have a lower capacity, but a higher specific power
and long life.
|Battery market share (Avicenne
Like the LFP and NMC, LMO cells may be
used in batteries which are in medical devices, hobby
equipment, e-bikes and even find use in EVs.
Another battery is
the lithium-air (Li-air) cell; a metal-air battery that
uses lithium oxidation at
the anode and reduction of oxygen at
the cathode to induce a current flow. The reason
behind the drive from EV manufacturers for Li-air battery
technology is that pairing lithium and oxygen (from air) can
theoretically lead to electrochemical cells with the
highest specific energy possible.
The energy density of
gasoline is approximately 13 kWh/kg, which corresponds
to 1.7 kWh/kg of energy provided to the wheels after
losses. Theoretically Li-air can achieve 12 kWh/kg
excluding the oxygen mass and deliver the same
1.7 kWh/kg to the wheels, after losses from
over-potentials, other cell components and battery pack
expects Li-air issues to be overcome and commercialised by
battery composition and supply
The six Li-ion
battery chemistries - LTO, LFP, LMO, NMC, LCO and NCA - use
varying amounts of lithium in their cathode and electrolyte
According to John
Petersen, a global thought leader on energy and
sustainability issues, a Li-ion battery with perfect
electrochemical efficiency would need 80 grams of lithium per
kWh of capacity, but "perfection doesn't exist in the real
world, the industry average is closer to 160
Peterson goes on to
say "while LTO cells don't use carbon-based anodes, the five
remaining chemistries use about 1kg of processed carbon
per kWh of battery capacity".
Supply 2015 (metric tonnes)
battery mineral supply and demand. Source: John Peterson,
Investorintel - based off Avicenne Energy
When Avicenne Energy
forecast cathode active materials in 2012, the study
concluded that while NMC and LCO chemistries would still
dominate the market, LFP would become a new significant
player in the cathode space.
| Cathode active materials, worldwide
battery market 2012-2025 (Avicenne Energy)
Cathode materials are
heavily dependent on the cost of the chemistry's active
materials, with UBS revealing that 70% of the price of a
lithium battery is accounted for by the raw
Cobalt supply difficulties could be a major
blockage when it comes to cheap Li-ion technology, with no
primary cobalt mine in existence and very little
transparency. Li-S batteries are already significantly
outperforming Li-ion batteries incorporating cobalt alloy
cathodes and could be a replacement as a cathode material as
cobalt prices rise.
Griffin, Managing Director of Lithium Australia, told IDC
Technologies Lithium Battery Conference delegates that "the
Li-S configuration, as well as being a prime contender in
resolving cobalt supply issues, may even come to dominate the
portable energy storage space in due course".
that "while commercialisation of Li-S cells is in its
infancy, the potential to substitute a cathode material
costing US$200/tonne (sulphur) for one costing
US$24,000/tonne (cobalt) while achieving a fivefold increase
in efficiency is beguiling".
Supplying those materials today are a
vast array of companies, summarised by Avicenne in the below
graphs. In addition to those companies dominating the space,
recent new entrants in the field include 3M LG Chem, Du Pont,
BASF, Mitsubishi and Dow.
Battery material suppliers (Source: