Popular Mechanics - USA (2022-01 & 2022-02)

Li+

Li+

Li+

Li+

Li+

Li+

Li+

Li+

Li+

e-

Li+ Li+ Li+

Li+

Li+

Li+

Li+ Li+

Li+

H O W

L I T H I U M - I O N

B A T T E R I E S

WORK

HARVARD’S

LAYERED

ELECTROLYTE

BATTERY

The Harvard cell’s con-
struction is unique for its
three layers of lithium-
compound electrolytes.
The outer layers are
highly stable, but suscep-
tible to dendrites. The
middle layer is unstable
but stops dendrites. Li
says the design is more
effective for preventing
dendrite damage—which
the battery’s 10,000
cycles certainly support.

Lithium-ion batteries
operate on the same
principles regardless of
their materials. To power
a device, lithium ions
travel from the anode
(negative) through the
electrolyte and to the
cathode (positive), dis-
charging electrons. To
recharge, they receive an
electron and travel back
to the anode. A tradi-
tional lithium-ion battery
uses a liquid electrolyte
with a separator between
the electrodes to pre-
vent short-circuits while
allowing the ions to pass.
In a solid-state battery,
the electrolyte is a solid
material, like a ceramic,
which stops the growth
of dendrites and also pre-
vents short-circuits.

lithium anode

graphite

coating

electrolyte #1

chemical

name:

Li5.5PS4.5Cl1.5

or LPSCI

electrolyte #1

chemical

name:

Li5.5PS4.5Cl1.5

or LPSCI

cathode

electrolyte #2

chemical

name:

Li10Ge1P2S12

or LGPS

negative separator

electrode layer

positive

electrode layer

charge discharge

anode current

collector

ultra-thin

lithium

metal

solid

ceramic

electrolyte

cathode

current

collector

solid

catholyte

chemical name:

LiNi0.8Co0.1Mn0.1O2

or NMC 811

liquid

electrolyte

44 January/February 2022

ILLUSTRATION BY COLIN MCSHERRY