Why your phone battery gets worse over time - George Zaidan
A drop of gasoline, a match,
and a battery, all store energy—
but, after each expends its energy,
only the battery is recyclable.
That's because, chemically speaking,
a dead battery is actually not
that different from a fresh one.
Most of the batteries we use
today take advantage
of the fact that some metals like
to release electrons
and others like to accept them.
For example, in a typical
alkaline double-A battery,
zinc metal reacts with hydroxide ions,
changing into zinc oxide and releasing
electrons at the negative terminal.
The electrons travel through, say,
a light bulb,
and then return to the battery
at the positive terminal,
where they’re accepted
by manganese dioxide.
Different batteries use different
combinations of metals,
and sometimes non-metals like graphite,
but the basic idea is to use
a pair of chemical reactions
to generate a stream of electrons.
Almost all batteries,
even single-use batteries,
are theoretically rechargeable.
That's because the metals and other
chemicals are still right there.
That’s very different than in,
say, gasoline,
where the liquid hydrocarbon molecules
are converted to gases.
You can't convert exhaust
back into gasoline,
but, with some work you can convert,
say, zinc oxide back to zinc.
So then what's the difference
between these and these?
The short answer is that trying
to recharge a single-use battery
doesn’t just force these reactions
to run in reverse.
It also results in a bunch of side
reactions that produce
useless contaminants,
reducing a battery’s capacity;
and it could even damage
the internal structure of the battery,
leading to a loss of electrical contact
and failure.
Rechargeable batteries are engineered
to avoid these issues.
Look at this lithium-ion battery.
Both sides have an atomic-level structure
that you can imagine as lots of docks.
So when the battery is powering something,
the lithium “ships” give up their
electrons to power the circuit,
and then sail over to the other side
of the battery,
dock in an orderly, organized way,
and meet up with their
now-lower-energy electrons.
When the battery is being charged,
the opposite happens.
Over the course of hundreds,
sometimes thousands, of charge cycles,
some of the lithium ion ships
sort of veer off course
and engage in side reactions,
producing stuff that increases
the internal resistance of the battery,
which in turn makes it lose
efficiency and power
until it inevitably dies.
Even when that happens,
you can bring dead batteries back to life—
whether they’re rechargeable or not—
by recycling them.
The heart of most battery recycling
is a process called smelting,
which is basically just melting
the metallic parts.
This drives off impurities,
returning metals back to their
initial, orderly state.
Unfortunately, in many countries you can’t
just toss household batteries
in with your regular recycling.
You have to take them to a battery
collection point or recycling center.
Same goes for more complicated
rechargeable batteries:
you need to bring them
to a collection point
or send them back to the company
you bought them from.
It’s a pain, but absolutely
worth the time and effort,
because recycling batteries is critical.
Not only does it prevent
potentially toxic battery metals
from leaking into the environment,
it conserves scarce— and vital— resources.
Earth has about 22 million tons
of lithium—
enough for about 2.5 billion EVs.
That sounds like plenty, but it’s only
25% higher than the number of EVs
experts believe it’ll take to reach
net zero emissions by 2050,
and that doesn’t even account for laptops,
phones, and anything else
that uses a lithium-ion battery.
Currently, though, most lithium-ion
batteries are not manufactured
with recycling in mind.
The designs are intricate
and non-standard,
and the components are held together
by almost indestructible glues.
So today, less than 5% of lithium-ion
batteries are recycled.
Regulations that clearly define
who is responsible for a spent battery
and what should happen to it
can boost recycling dramatically.
For example, lead-acid batteries are
generally subject to stringent regulations
and are recycled at much higher rates
than lithium-ion batteries.
Over the next century, we’ll need
to recycle huge numbers of EV batteries,
so scientists are working on making
the battery recycling process cheaper
and more environmentally friendly.
Smelting uses a lot of energy and,
depending on the type of battery,
can release harmful by-products.
In addition to regulations, industrial
processes, and our own individual choices,
battery tech will also continue to evolve.
There are proof-of-concept batteries
being developed that can convert
physical force, ambient sound,
and even pee into electricity.
But if your top priority is to make your
number one source of power, number one,
sorry to say, but urine for a long wait.
