Cause Li-ion battery life decreases gradually after use

Every time you charge lithium-ion batteries, its energy storage capacity decreases little by little. That's why your mobile device no longer holds the battery as long as you bought it. But thanks to the research done by Lawrence Berkely, Brookhaven and Stanford University labs, researchers finally know exactly what happened to the battery and, more importantly, how. to extend its life.

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When li-ion batteries are used (battery discharge), lithium (Li +) ions will run from cathode to anode to cathode via a dry electrolyte. This process will power your mobile device. However, this cycle is not repeated perfectly.Every time lithium ions move in the battery, they will cause physical structural changes at the electrodes. This is the key to reducing the battery's energy storage capacity.

Co-author of the study, materials scientist Huolin Xin, said: "We have discovered a surprising phenomenon that happened in both of the main components in the battery. Previously, when observed under nanoscale, lithium ions caused uneven erosion and created intrinsic holes in the molecular structure of the material at the electrodes . can imagine similar to rust on steel ".

In fact, when Li + ions move through an anode of Nikel Oxide during battery discharge, it will gradually break down the original structure of the material, thereby reducing their operability. Houlin further explained that: "Nickel anode Oxide will turn into Nickel metal due to the unevenness of the nanoscale or defect on the surface structure. And Li + ions are the agents that create cracks in the surface. armor face covering the anode ".

On the other hand, during charging, lithium ions will move through the cathode and form a layer of insulating salt on the surface . It is this salt layer that reduces the energy storage capacity of the entire battery . Houlin also added that by observing under an electron microscope, the salt crystallization process around the cathode will proceed as quickly as the higher the input voltage. Therefore, the higher the charging voltage, the faster the battery deteriorates.

Each orange dot represents an atomic column at the cathode that is observed under an electron microscope.Scientists have discovered that Li + ions tend to move along the middle layer of atoms.After the charging / discharging process takes place, the layer of flaking atoms will stick around the cathode surface (blue line), thereby reducing the battery's performance.

Knowing the exact cause of the deterioration of battery life, researchers have proposed ways to design stronger batteries and survive longer. Houlin said: "We can completely coat a layer of antifreeze on the surface of the cathode. It is a nano-sized powder compound made up of advanced nanotechnology. Experts at the lab Berkely are working on making this kind of compound ".

Since li-ion batteries were born, the technology world has seen this as an advanced battery generation with many advantages. However, outstanding issues have been continuously explored by researchers and proposed remedies. If the nano-coating compound was successfully developed by researchers, this would be a revolution in creating new generation of lithium batteries with the ability to operate at high efficiency for a much longer time. much more than before.