Batteries
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(NiMH) and lithium- ion (Li- Ion). NiMH batteries use Ni(OH) 2 in the positive electrode and metal hydride in the negative electrode, while Li- Ion
batteries use a metal oxide containing lithium in the positive electrode and
graphite in the negative electrode (Young, et.al, 2013). The US Department
of Energy (2017) describes NiMH batteries as having been successfully
used because they are safe, are capable of handling rough conditions, have
a substantial life span, and have acceptable specific energy and specific
power (specific energy is how many kilowatt hours [kWh] can be stored
per kilogram of mass, whereas specific power is the maximum kilowatts
per kilogram a battery can deliver [Young et. al, 2013]). However, a few
drawbacks of NiMH batteries are that they are expensive, generate heat,
have high self- discharge, and lose hydrogen. Li- Ion batteries are now
emerging as serious competitors to NiMH batteries due to their decreasing
costs, increasing reliability, and good life span. One way to measure battery
cost is the cost per kWh of energy. One goal is to lower the cost to $100/
kWh to be more competitive with the purchase price of current combustion engine vehicles (Chediak, 2017). It is projected that this goal is attainable, likely with Li- Ion batteries, by 2020 (Chediak, 2017; McMahon, 2018;
Morris, 2018).
Currently there is also significant interest in solid- state batteries because
they have the potential to increase energy density. If battery energy density
can be doubled, it will be very beneficial for EVs because the range of a
vehicle could be increased to about 600 km (373 miles). Many investigators
are working on solid- state batteries, with estimated global expenditures of
more than $500 million/ year in 2018 (Jaffe, 2019). There has been significant
progress in developing solid- state batteries, and there are several different
materials that are of interest (Zheng et al., 2018; Xin et al., 2017). By 2030,
there may be commercial solid- state batteries in EVs that can be purchased
(Gilboy, 2018).
There are several issues that are important in battery development,
including energy density, durability, impact of temperature on battery service life, time to charge, operational features, and cost. Developing a commercial battery that meets all of the requirements for long- term use takes
time, and important issues must be resolved successfully.
The design of batteries for grid energy storage can be different from those
designed for EVs, particularly in terms of energy density. Energy density
is more important for EVs, but systems with more volume or weight are
unproblematically able to be used for grid storage. Research to improve the
anode is being carried out by a number of research groups (Ball, 2019). There
are a number of new battery designs that have promise; however, they need
to be taken through the final stages of development and then produced commercially. The cost of production has been decreasing and the new battery
needs to be competitive with the other alternatives at the time the new
battery factory is ready for production. There is global competition that must
be considered and trade agreements may be important. If prices of storage
61
61
(NiMH) and lithium- ion (Li- Ion). NiMH batteries use Ni(OH) 2 in the positive electrode and metal hydride in the negative electrode, while Li- Ion
batteries use a metal oxide containing lithium in the positive electrode and
graphite in the negative electrode (Young, et.al, 2013). The US Department
of Energy (2017) describes NiMH batteries as having been successfully
used because they are safe, are capable of handling rough conditions, have
a substantial life span, and have acceptable specific energy and specific
power (specific energy is how many kilowatt hours [kWh] can be stored
per kilogram of mass, whereas specific power is the maximum kilowatts
per kilogram a battery can deliver [Young et. al, 2013]). However, a few
drawbacks of NiMH batteries are that they are expensive, generate heat,
have high self- discharge, and lose hydrogen. Li- Ion batteries are now
emerging as serious competitors to NiMH batteries due to their decreasing
costs, increasing reliability, and good life span. One way to measure battery
cost is the cost per kWh of energy. One goal is to lower the cost to $100/
kWh to be more competitive with the purchase price of current combustion engine vehicles (Chediak, 2017). It is projected that this goal is attainable, likely with Li- Ion batteries, by 2020 (Chediak, 2017; McMahon, 2018;
Morris, 2018).
Currently there is also significant interest in solid- state batteries because
they have the potential to increase energy density. If battery energy density
can be doubled, it will be very beneficial for EVs because the range of a
vehicle could be increased to about 600 km (373 miles). Many investigators
are working on solid- state batteries, with estimated global expenditures of
more than $500 million/ year in 2018 (Jaffe, 2019). There has been significant
progress in developing solid- state batteries, and there are several different
materials that are of interest (Zheng et al., 2018; Xin et al., 2017). By 2030,
there may be commercial solid- state batteries in EVs that can be purchased
(Gilboy, 2018).
There are several issues that are important in battery development,
including energy density, durability, impact of temperature on battery service life, time to charge, operational features, and cost. Developing a commercial battery that meets all of the requirements for long- term use takes
time, and important issues must be resolved successfully.
The design of batteries for grid energy storage can be different from those
designed for EVs, particularly in terms of energy density. Energy density
is more important for EVs, but systems with more volume or weight are
unproblematically able to be used for grid storage. Research to improve the
anode is being carried out by a number of research groups (Ball, 2019). There
are a number of new battery designs that have promise; however, they need
to be taken through the final stages of development and then produced commercially. The cost of production has been decreasing and the new battery
needs to be competitive with the other alternatives at the time the new
battery factory is ready for production. There is global competition that must
be considered and trade agreements may be important. If prices of storage