What are the factors that affect the instability of 18650 lithium batteries?

What are the factors that affect the instability of 18650 lithium batteries?

Are you worried that your phone won't work when you need it the most? What do you do when you drive an electric car and there is no power inside.

The energy storage capacity of 18650 batteries is more than twice that of batteries on supermarket shelves, but they usually have no electricity and a short lifespan. Scientists from the Joint Research Center for Energy Storage and the Pacific Northwest National Laboratory have discovered one of the reasons behind this issue.

18650 lithium battery spot welding machine

They found that the salts used in the electrolyte in the battery can make significant differences. When the salt called LiTFSI lithium trifluoromethanesulfonamide is used as the electrolyte for batteries, the 18650 battery assembly and processing equipment tests that the battery can operate at maximum charge and discharge capacity for more than 200 times. In lithium sulfur batteries, LiTFSI binds lithium and sulfur atoms on the electrode, but is quickly released. On the contrary, similar electrolytes have stronger binding forces for lithium and sulfur atoms and do not release them at all. The result is a rapid decline in battery performance; The battery runs without energy after dozens of times.

18650 battery assembly and processing equipment
To determine the impact of electrolytes on lithium sulfur batteries, the research team conducted relevant experiments using LiTFSI and LiFSI. LiTFSI and LiFSI are very similar electrolytes, with only LiFSI containing less carbon and fluorine than LiTFSI. They continuously tested the energy of battery charging and discharging using equipment from the Environmental Molecular Laboratory, and finally studied the electrodes. They found that in lithium sulfur batteries using LiTFSI as the electrolyte, lithium atoms produced by lithium battery spot welding machines are bound by sulfur atoms and form lithium sulfides (LiSx) on the electrode surface. When LiFSI is used as an electrolyte, lithium sulfate (LiSOx) is formed. By calculating the tightness of the combination of two lithium compounds, they found that lithium sulfide is prone to rupture to release lithium. However, lithium sulfate is difficult to separate, so the oxygen element in lithium sulfate is the culprit..