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Andrew Stark
PHYS-P 310
12/6/16
Advanced Battery Chemistry
In order to mitigate greenhouse gas emissions to slow and potentially halt or even reverse
anthropogenic climate change, there must be an enormous and global decrease in use of fossil
fuels and a corresponding increase in use of renewable energy. Fortunately, the economic
prospects for renewable energy are quite favorable and wind and solar have particularly
favorable outlooks, especially relative to coal.1, 2 The development of these renewable energy
sources is critical to confronting climate change and will hopefully be supported by private and
public interests, in addition to the aforementioned economics that result from technological
improvements in cost and efficiency. Unlike fossil fuels, most renewable energy sources lack
inherent storability, apart from sources like biomass or artificial photosynthesis.3 Fossil fuels are
stable gases, liquids, or solids, but the electricity that is generated from solar energy, for
example, must be stored if not utilized immediately. In order to ensure a steady supply of energy
for consumers, energy storage is particularly important for clean energy generation that naturally
fluctuates, which applies to both wind and solar. On the other hand, power plants can burn fossil
fuels according to consumer demand. Whether renewable energy is stored through flywheels,
heat, electrolysis of water, gravitational potential energy, or batteries, the development of energy
storage must complement the development of renewable energy technologies in order to support
a smooth transition away from fossil fuels. The previous sentence applies to virtually all energy
consuming sectors of society, including residential and commercial, industrial, and
transportation. The content of the current paper contained hereafter will mostly relate to energy
storage through batteries, battery chemistry, and research and development in the areas of
batteries and battery chemistry, especially as it relates to the transportation sector.
Andrew Stark
PHYS-P 310
12/6/16
Basically, a battery is an apparatus for storing electrical energy in the form of chemical
energy, the former of which is presumably obtained from the electrical grid or from a small scale
renewable source. Batteries can consist of multiple cells, of which are compartmentalized into
two separate cells. One half cell contains the negative electrode, or the anode, along with an
electrolyte, whereas the other cell contains the positive electrode, or the cathode, along with the
same electrolyte. The electrolyte may be solid or liquid, but ultimately serves as the medium for
the transport of ions between the half cells. Furthermore, the electrolyte may be shared by both
half cells or may be separated by a semi-permeable membrane that allows for translocation of
select ions. The translocation of ions is vital for the function of the battery, as ion movement
through the electrolyte complements electron movement through an external circuit between the
electrodes, which can do useful work during discharge.3 During recharge, the solid product from
discharge must be converted back to the solid reactant, both of which have distinct crystal
structures and densities. The interconversion of solids causes mechanical stress in the anode and
cathode, which ultimately results in partial degradation of the electrodes and limitation of the
battery’s number of charge-discharge cycles.4 The voltage difference between the electrodes
depends on the chemistry of the electrodes and can be increased when multiple cells are joined
together. Moreover, voltage decreases with the discharge of a battery, as internal battery
resistance increase during discharge.3
Batteries generally exist either as non-rechargeable or rechargeable, which depends on
the reversibility of the chemical reaction within the battery, and the current paper will focus on
the latter of the two battery types, as the former lacks sustainability due to its disposability and
the latter is more relevant to expediting a societal transition to renewable energy.3 Different
battery chemistries result in different battery properties, including specific energy, specific
Andrew Stark
PHYS-P 310
12/6/16
power, self-discharge rate, number of cycles, and cost. Given a specific battery size within a
vehicle, specific energy roughly indicates vehicle driving range and specific power indicates the
rate of purposeful discharge, both of which are very attractive to maximize, especially in
conjunction.3 Unfortunately, electric vehicles cannot be constantly connected to the grid and
solar and wind vehicles are generally unviable, so larger vehicle driving ranges are more
appealing to customers as they enable travel over greater distances without recharge.3
Researchers are especially interested increasing the specific energy of batteries in order to
increase electrical holding capacity, or the resulting vehicle driving range in the context of
transportation.
Some traditional examples of rechargeable battery chemistries include lead-acid, nickel
metal hydride, and lithium-ion. Lead-acid batteries are widely used to start automobile engines,
nickel metal hydride batteries are used in hybrid vehicles, and lithium-ion batteries are often
used for electric vehicles. Lead-acid batteries have a relatively low specific energy and therefore
are often require multiple cells and modules for sufficient output.4 On the other hand, lithium ion
batteries are appealing as electric car batteries since they have a high specific energy and a
relatively high specific power.3, 4 The chemistry of lithium-ion batteries largely depends on the
materials of the electrodes and the binding strength of lithium cations to the two materials.4
Despite its desirable chemical properties, lithium ion batteries are expensive to produce and
accessible lithium is limited in amount with an estimate of enough supply for about 500 to 600
million car batteries, which is roughly equivalent to the number of cars that currently exist.3 As
previously mentioned, batteries have a limited longevity, so the aforementioned supply of
lithium would be even limited unless the batteries are properly recycled. Accordingly, battery
research also seeks to produce competitive batteries that do not rely on lithium.
Andrew Stark
PHYS-P 310
12/6/16
Rechargeable sodium batteries are relatively new alternatives to lithium-ion batteries and
they address issues of cost and availability, as an incredibly large supply of sodium exists.
Following lithium, sodium is the next heaviest alkali metal and therefore shares much of the
same chemical reactivity as lithium. The design for a sodium-ion battery is similar to that of a
lithium-ion battery and also manifest in a high specific energy battery. Moreover, it is able to
operate at room temperature and does not produce corrosive by-products, which occurs in some
other sodium batteries. Sodium-ion battery chemistry research is a relatively new, but the
prospects for commercial use of the sodium-ion chemistry are positive.3 Another developing
alternative to lithium-ion batteries is the lithium-air (Li-O2) battery, which utilizes molecular
oxygen from the atmosphere to operate.5 While this battery still utilizes lithium, researchers at
the University of Cambridge have produced a lithium-air battery with an energy density about
ten times the size of a lithium-ion battery, more than 2,000 charge-discharge cycles, and an
efficiency of 93.2%. This battery performs exceptionally well in lab and would require much less
lithium to store the same amount of energy as a lithium-ion battery, which would translate to
cheaper and smaller batteries. It is widely considered to be the next generation battery, but
lithium-air batteries are estimated to require another decade of development before being
commercially viable.6, 7 Nonetheless, the commercialization of lithium-air batteries would be
hugely impactful on the transportation sector, as electric vehicles lack accessibility due to their
cost, which would be largely reduced assuming the prices for lithium do not drastically increase.
Should lithium-air batteries never commercialize, another form of a metal-air battery would
hopefully find commercial success as these types of batteries generally boast high specific
energies.5, 8
Andrew Stark
PHYS-P 310
12/6/16
Battery chemistry research also seeks to enhance batteries for stationary use. Sodiumsulfur share some chemical features with sodium-ion batteries, but are mostly useful for small or
large scale stationary use. The arrangement of the battery yields a very high specific energy,
however, the cell generally must be operated at high temperatures and forms a corrosive
discharge product, both of which are potential hazards. These drawbacks generally limit sodiumsulfur batteries to more controlled use, like grid backup power storage.3 Another battery type that
has high usefulness for large scale stationary use is the flow battery. Flow batteries are distinct
from traditional rechargeable batteries as their energy storage capacity is directly related to the
size of their electrolyte storage tank, which can be tremendously scaled up and possibly be
utilized for large-scale electrical storage.3 Stationary batteries face fewer limitations than
batteries used for transportation, as the latter are more often restricted in size and weight than the
former.
Overall, the chemistry and practical characteristics of a battery are determined by the
materials that respectively compose its anode, cathode, and electrolyte. The most appealing
batteries are able to maximize specific energy, specific power, rechargeability, recharge rate, and
efficiency while minimizing cost. The current paper has explored some of the basic science
behind batteries, the importance of battery research to the transportation sector and renewable
energy, and some battery chemistries that are currently in use or under development. Despite this
short report, battery research as a whole is extremely expansive and involves contributions from
disciplines like materials chemistry, inorganic chemistry, electrochemistry, engineering, and
physics.
Andrew Stark
PHYS-P 310
12/6/16
Works Cited
1. Bloomberg. The Way Humans Get Electricity Is About to Change Forever.
https://www.bloomberg.com/news/articles/2015-06-23/the-way-humans-get-electricityis-about-to-change-forever (accessed Dec 4, 2016).
2. Bloomberg. Economics to Keep Wind and Solar Energy Thriving With Trump.
https://www.bloomberg.com/news/articles/2016-11-23/economics-will-keep-wind-andsolar-energy-thriving-under-trump (accessed Dec 4, 2016).
3. Dunlap, R. Sustainable Energy; Cengage Learning: Stamford, 2015; pp. 486-509.
4. Engel, T.; Reid, P. Physical Chemistry, 3rd ed.; Pearson Education, Inc.: London, 2013;
pp. 272-276.
5. Forbes. Lithium-Air Battery Breakthrough May Mean Game Over For Gasoline.
http://www.forbes.com/sites/williampentland/2015/10/31/lithium-air-batterybreakthrough-may-mean-game-over-for-gasoline/#53fc84ab5a00 (accessed Dec 5, 2016).
6. Liu, T.; Leskes, M.; Yu, W.; Moore, A. J.; Zhou, L.; Bayley, P. M.; Kim, G.; Grey, C. P.
Cycling Li-O2 batteries via LiOH formation and decomposition. Science. 2015, 350, 530533.
7. Arstechnica. Lithium-Air Battery Research Shows Potential Paths to Next-Gen Batteries.
http://arstechnica.com/science/2015/10/lithium-air-battery-research-shows-potentialpaths-to-next-gen-batteries/ (accessed Dec 6, 2016).
8. Sandhu, S. S., Brutchen, G. W., & Fellner, J. P. Lithium/air cell: Preliminary
mathematical formulation and analysis. J. Power Sources, 2007, 170, 196-209.