You gotta love Elon Musk—the man is everywhere. Current Musk projects include Tesla Motors,
Power Wall, and SpaceX. Take a look at the drawing
board, and things get interesting. Hyperloop promises to
speed passengers from Los Angeles to San Francisco in
35 minutes; the Boring Company wants to cut costs of
building tunnels by 75 percent, and recently made 20,000
flamethrowers available as a publicity stunt.
As ECN readers know very well, Tesla’s vehicles and
Power Wall both rely on batteries to store and supply
electrical energy. The market for batteries is on a roll as
HEV/EV adoption rates continue to increase and utilities
look for a way to balance supply and demand, as well as
store the intermittent production from alternative energy
sources such as photovoltaic (PV) cells and wind turbines.
According to GTM Research (Figure 1), the annual
deployment for energy storage devices will total almost
1 GW in 2019; installations that capture energy from
residential or commercial PV (solar) installations—
commonly known as “behind-the-meter” deployments—
will comprise half the annual market by 2021. The U.S.
energy storage market will be worth an estimated $3.1
billion by 2022, a nine-fold increase from 2016 (and
seven-fold from 2017).
Figure 1: U.S. annual energy storage deployment forecast
2012–2022. (Image Source: GTM)
The rise in battery-based energy storage is intimately
linked with lithium-ion (Li-ion) chemistries: according
to GTM analysts, they made up at least 97 percent of
all storage capacity deployed in 2016. Li-ion also rules
the roost in electric and hybrid vehicles, especially since
Toyota, the last major holdout, switched most models
of its flagship Prius hybrid from nickel-metal-hydride
(NiMH) to Li-ion in the 2016 model year.
Reflecting the increase in demand, production volumes
have ramped up, while Li-ion battery cell prices have
fallen by about 60 percent in five years to around $139
per kilowatt-hour. Global battery manufacturing is
forecast to double from 2017 to 2021 and reach 278
GWh per year, accompanied by a further price reduction
of more than 40 percent.
Tesla is casting a long shadow over the Li-ion
market. To protect against potential shortages, they’re
moving to secure their own source of batteries. Their
Gigafactory 1 in Sparks, NV, began production of
Panasonic’s Li-ion design in 2017. When completed in
2020, the factory will produce 35 GWh of batteries
yearly, primarily for in-house use. The company is
already planning up to five Gigafactories.
Inside the Li-ion Battery
In spite of worldwide efforts to find better alternatives,
why is Li-ion still slaying all comers?
One reason is the hurdles any challenger must surmount
to make it to the finish line. There’s no shortage of
candidates, and researchers regularly claim breakthroughs
in battery chemistry, energy density, or charging time. So
far, they’ve all been hobbled by some combination of high
production costs, reliance on rare materials, problems
with recycling or disposal, or limited number of charge/
Lithium (Li) is also a formidable opponent. With atomic
number 3, it’s the lightest metal. Li has the greatest
electrochemical potential and largest specific energy per
weight, both highly desirable in a battery. A Li battery is non-rechargeable, while the pure metal is unstable, flammable,
and potentially explosive when exposed to air or water,
so research has concentrated on Li compounds that offer
greater safety at the cost of slightly lower energy density.
Several Li compounds are in use for the positive
electrode (cathode). Lithium nickel manganese cobalt
oxide (NMC), lithium iron phosphate (LFP), and lithium
cobalt oxide (LiCoO2) are three examples, each with
characteristics optimized for different applications.
In current Li-ion batteries, the negative electrode
(anode) is most commonly made of graphite.
The liquid electrolyte consists of Li salts in an organic
solvent such as ethylene carbonate or dimethyl carbonate.
During operation, Li-ions move from the anode to the
cathode during discharging, and in the reverse direction
By Paul Pickering, Technical Contributor