GAO-23-106332 Advanced Batteries
Science, Technology Assessment,
and Analytics
SCIENCE & TECH SPOTLIGHT:
ADVANCED BATTERIES
/// THE TECHNOLOGY
What is it? A battery is an energy storage device that consists of a
chemical solution called an electrolyte and a separator that serves as a
barrier between two terminals—an anode and a cathode. During use, the
electrolyte allows the flow of charged particles, such as lithium ions, from
the anode to the cathode. This produces an electric current that flows out
of the battery to a device through an external circuit. Charging the battery
reverses this process. Different applications, such as electric vehicles or
electric grid storage, require different battery properties—such as size,
weight, portability, or duration of use—each of which comes with trade-offs.
Figure 1. Example of How Rechargeable Lithium-Ion Batteries Work During Use
Most current battery research focuses on lithium-based systems, which
can store a lot of energy in a small volume and undergo many charging
cycles. According to the American Chemical Society, lithium-ion batteries
will make up 70 percent of the rechargeable battery market by 2025. The
lithium supply would need to increase to meet this demand, prompting
efforts to develop advanced battery technologies that use more earth-
abundant materials and reduce reliance on foreign-produced materials.
How does it work? Scientists are exploring how to replace critical
elements in various components of lithium-ion batteries to improve their
performance and safety while using more sustainable, widely-available,
and cost-effective materials. For example, the standard material used
for the anode of lithium-ion batteries is graphite—the same flaky carbon
material used in pencils. However, silicon is a cheap and more readily
available material that is safer and can potentially store 10 times as much
lithium by weight.
Alternative cathode materials are also being tested for lithium-ion
batteries. For example, different metal oxides are typically used in the
cathode to interact with the lithium and give the battery different traits.
Alternatively, lithium-sulfur batteries contain a sulfur-based cathode that
reacts with lithium ions to form lithium sulfide, which could allow cells to
store 5 times as much energy as a conventional lithium-ion battery. Sulfur
is an abundant element that can be mined in the U.S. This makes it a
more sustainable alternative to other commonly used metals in lithium-
ion battery cathodes, such as cobalt, which is costly and may come from
overseas mines with controversial labor or mining practices.
Another advancement replaces the typically liquid electrolyte—which
can be flammable and can catch fire when overheated—with safer, more
stable materials. For example, using a solid electrolyte such as a ceramic
or glassy material may prevent the build-up of lithium salt crystals that can
short the battery’s circuit and cause fires. These solid-state batteries have
the potential to store twice the energy of conventional lithium-ion batteries,
increasing how long the battery can work before it needs to be recharged.
Lithium-ion batteries are generally limited to short duration use.
Rechargeable metal-air batteries and flow batteries may allow for longer
storage duration, which could provide advantages in storing intermittent
energy produced from renewable sources for use when needed. Metal-
air batteries use a metal anode paired with a porous cathode to allow
oxygen flow from the surrounding air. Because one terminal is porous,
these batteries are lighter than conventional batteries. Researchers have
investigated a variety of metals—such as aluminum, lithium, sodium, tin,
and zinc—for potential use. Each comes with different advantages and
disadvantages. For example, the aluminum-air battery is lightweight,
recyclable, made of common materials, and cheap, but it is difficult to
recharge due to a tendency to corrode.
Unlike standard rechargeable batteries, flow batteries store liquid
electrolytes in external tanks. Because there is no size limit for external
tanks, the storage capacity of the flow battery can be scaled up as
needed. This makes them ideal for storing large amounts of energy for the
grid but less useful in portable applications like electric vehicles.
Figure 2. Example of How Flow Batteries Work for a Grid Application
DECEMBER 2022
WHY THIS MATTERS
Batteries are critical for powering many of our everyday
technologies. Increased demand in areas such as
transportation and electric grid storage will require longer-
lasting batteries with more capacity. Scientific advances in
batteries could meet the demand for more energy storage
while also ensuring these next-generation batteries are safe,
cost-effective, and sustainable. However, challenges remain.
