Thursday, February 25, 2021
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Why your phone battery loses charge after one year

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.


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.


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.’



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