Why your phone battery lasts for DAYS when it’s new, but loses charge in a few hours after a year: Latest research reveals how lithium-ion cells degrade and could pave the way for longer lasting batteries
- The common understanding of how lithium-ion batteries work is actually wrong
- Charged particles in a battery move at random, with ions gathering in groups
- These densely-concentrated regions produce a lot of heat and damage the cell
- As a result, the lifespan of a battery decreases dramatically over time
- Researchers believe they can use this knowledge to create a next-generation batteries that will be more durable and longer lasting
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Scientists have finally unpicked the mystery behind why smartphone batteries have such diabolical battery life after a year or so of use.
According to the latest findings, the commonly-held belief of how a lithium-ion battery works is incorrect.
Instead of charged particles flowing in a single, uniform direction inside the battery, they move back and forth in a random pattern of movement.
According to the researchers, this knowledge could be used to create batteries that last longer and hold their charge without damaging the lifespan of the cell.
This could have applications for the mass roll-out of electric vehicles as well as improving the lifespan of billions of gadgets worldwide, scientists say.
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Scientists have finally unpicked the mystery behind why smartphone batteries have such diabolical battery life after a year or so of use. They claim the understanding of how batteries actually work has been widely misunderstood (stock)
The breakthrough study came from researchers at Stanford University, MIT and the University of Bath who discovered that our understanding of how a lithium-ion battery – the type that powers all our favourite gadgets – works, is incorrect.
It is known that charged particles flow between a positive electrode to a negative electrode through a material (electrolyte) and this movement creates a charge.
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However, it was previously believed the lithium was anisotropic, a property that means it flows in a single direction, with the particles in a single, uniform route through the battery.
However, it has now been found that the reality is vastly different and the particles, known as ions, actually ebb and flow back and forth through the electrolyte.
This can create random pockets of densely packed ions inside the cell, which create large amounts of heat, damaging the lifespan of the battery.
HOW DO LITHIUM ION BATTERIES WORK?
Batteries store and releases energy by moving electrons from one ‘end’ of the battery to the other.
We can use the energy from those moving electrons to do work for us, like power a drill.
These two battery ‘ends’ are known as electrodes. One is called the anode and the other is called the cathode.
Generally, the anode is made from carbon and the cathode from a chemical compound known as a metal oxide, like cobalt oxide.
The final battery ingredient is known as the electrolyte, and it sits in between the two electrodes.
In the case of lithium-ion batteries, the electrolyte is a salt solution that contains lithium ions—hence the name.
When you place the battery in a device, the positively charged lithium ions are attracted to and move towards the cathode.
Once it is bombarded with these ions, the cathode becomes more positively charged than the anode, and this attracts negatively charged electrons.
As the electrons start moving toward the cathode, we force them to go through our device and use the energy of the electrons ‘flowing’ toward the cathode to generate power.
You can think of this like a water wheel, except instead of water flowing, electrons are flowing.
Lithium-ion batteries are especially useful because they are rechargeable.
When the battery is connected to a charger, the lithium ions move in the opposite direction as before.
As they move from the cathode to the anode, the battery is restored for another use.
Lithium ion batteries can also produce a lot more electrical power per unit of weight than other batteries.
This means that lithium-ion batteries can store the same amount of power as other batteries, but accomplish this in a lighter and smaller package.
As a result, the battery loses the ability to hold a charge and we often find ourselves relying on portable chargers more often.
William Chueh, an assistant professor at Stanford, said: ‘We used very powerful X-rays from an accelerator, and we’re using these X-rays to look into these individual nanoparticles.
‘Our original expectation was that lithium moves in certain directions only. We actually saw lithium move in the direction it’s not supposed to move.’
Random pockets of densely packed ions create large amounts of heat in a cell which can damage the battery. As a result, many of us become reliant on portable chargers (stock)
The research made use of the SLAC National Accelerator Lab’s facilities at Stanford, which allowed the team of scientists to look at batteries on the nanoscale.
Dr Chueh elaborates on the phenomenon and explained that previous theories did not account for how the liquid interacts with the solid.
‘Kind of like in space, we think about how the particle behaves in a vacuum,’ he said.
‘But a battery doesn’t operate in a vacuum—it operates in a liquid.’
The team believe they will be able to fix this flaw by altering the transport pathway and allowing for more durable batteries in the future.
HOW DOES CHARGING A BATTERY WORK?
In their simplest form, batteries are made of three components: a positive electrode, a negative electrode and an electrolyte.
When a battery is charging, lithium ions are extracted from the positive electrode and move through the crystal structure and electrolyte to the negative electrode, where they are stored.
The faster this process occurs, the faster the battery can be charged.
The material a battery is made of can severely restrict this rate.
Graphite is a commonly used material for the negative electrode as it accepts positive ions well and has a high energy density.
In the search for new electrode materials, researchers normally try to make the particles smaller.
However, it’s difficult to make a practical battery with nanoparticles as it creates a lot of unwanted chemical reactions with the electrolyte, so the battery doesn’t last as long, plus it’s expensive to make.
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