A lot of the technology we use today was not around a while back like having smartphones
that's thousands of times faster than the computer that powered the first moon landing
what if your phone could last four days on a charge or an EV could go twice as far
charging minutes and cost less than its internal combustion counterpart
this will be made possible by solid state batteries the next generation of batteries
as the name suggests a solid state battery is a battery technology that uses a solid electrolyte
instead of the liquid or polymer gel electrolytes found in lithium ion or lithium polymer batteries
a battery's electrolyte is a conductive chemical mixture that allows the flow of electrical current
between the two electrodes a lithium ion battery consists of three main layers a cathode or
positive electrode an anode or negative electrode a separator which is an electrical insulator
that prevents short circuits and is made of a porous material and an electrolyte through which
lithium ions move from the anode to the cathode a battery can be thought of as the electrochemical
equivalent of rolling a ball uphill which requires work to be put into the system and letting it roll
back downhill on its own to release stored energy in a fully discharged cell the lithium in the cell
resides in the cathode when the cell is charged work is put into the system to drive lithium
ions from the cathode to the anode in the fully charged state the lithium ions sit in the anode
when the battery is discharged these lithium ions are allowed to move back through the electrolyte
and in the process energy can be extracted from the system just like the ball rolling downhill
can release its stored energy in the form of work solid state batteries still work in the same way
as current batteries do but the change to a solid electrolyte alters some of the battery's
attributes a similar sized solid state battery promises to have a higher energy storage capacity
charge significantly faster a longer lifespan and a lot safer than a conventional lithium ion
battery the immediate benefit of switching to a solid electrolyte is the increase in energy
density of the battery conventional liquid soaked battery separators are about 20 to 30 microns
thick compared to three to four micron separators in solid state batteries which is roughly seven
fold space saving a further increase in energy density can be obtained by ditching today's
standard anode material graphite for a lithium metal anode a paper published by a group from bmw
includes a chart showing a dozen different next generation cathode materials and three different
anode materials the chart clarifies that the energy density gains from using next generation
cathode materials are limited unless lithium metal is used as the anode traditional lithium ion cells
use a hosted anode in which the host material provides a structure to hold the lithium for
example in the case of carbon it takes six carbon atoms to hold one lithium atom if however an anode
of pure metallic lithium were used all the carbon in the anode could be eliminated and the energy
could be stored in a much smaller volume however it has been known that lithium metal anodes do not
work with conventional liquid electrolytes due to dendrite formation metal can build up on the anode
and slowly create dendrites needle-like formations and those can extend and puncture the separator
between the anode and the cathode which can cause short circuits and lead to fires or
even explosions it is widely believed that to make a lithium-metal anode battery one needs a
solid-state separator which is about as conductive as a liquid but resists dendrite formation and
does not react with the metallic lithium for more than 40 years the industry has been searching for
such a material in the past few years materials such as oxides sulfides phosphates solid polymers
ceramics and even glass have been used as solid electrolytes some of the main drawbacks of the
lithium ion batteries we use today which solid state is trying to solve is that cells can lose
about a third of their capacity within a decade of use where over time compounds in the liquid
can corrode internal battery components and can experience degradation or solid material build
up inside both of which lead to a degradation of battery capacity and overall performance
then there is the risk of leaking electrolyte and a high flammability which is a safety risk
solid state batteries aren't a new thing at all but their use in such a heavy duty application
such as in an automobile is they've been in use for many years in small devices like pacemakers
and rfid in the early 1830s michael faraday discovered the solid electrolytes silver sulfide
and lead fluoride which laid the foundation for solid-state batteries by the late 1950s several
electrochemical systems used a silver ion as the solid electrolyte but it had some unwanted
qualities including low energy density and cell voltages and a high internal resistance in the
1990s a new class of solid state electrolyte emerged developed by the oak ridge national
laboratory which was then used to make thin-film lithium-ion batteries as technology advanced into
the new millennium researchers and companies operating in the automotive and transportation
industries experienced a revitalized interest in solid state battery technologies in 2017
john goodinoff the co-inventor of lithium-ion batteries unveiled a solid-state battery using
a glass electrolyte and an alkali metal anode consisting of lithium sodium or potassium another
solid-state battery startup named quantumscape drew attention in 2018 when volkswagen announced
a hundred million dollar investment into the team's research becoming the largest stakeholder
joined by investor bill gates in january 2021 quantum scape revealed performance results of
their solid state battery after a thousand charge cycles the single layer cells retained ninety
percent of its energy capacity quantum scope targets to achieve an energy density of a thousand
watt hours per liter for their multi-layer cell which will provide a 40 increase in range compared
to the 2170 cell used in the tesla model 3 which has an energy density of 713 watt hours per liter
the main delay is currently caused by the stacking of single layer cells into a multi-layered battery
moving from lab reduction to mass scale production solid-state batteries are one
of several next-generation battery technologies that can solve the safety issues with lithium-ion
batteries to obtain a higher safety higher energy density and a longer battery lifetime