A new type of mixed electrolyte to improve the performance of lithium ion battery is helpful to establish sustainable energy supply

Lithium ion batteries (LIB), which are often used in commercial batteries, contribute to the contemporary ITC society, including electric vehicles and smart phones. LIBs are continuously charged and discharged back and forth between the positive electrode and the negative electrode through lithium ion (Li ion), and lithium ion electrolyte acts as an ion channel.

Photos (left), scanning electron microscope images (middle) and composite electrolyte structure diagram (right)

Organic electrolytes, such as liquid ethyl carbonate (EC) and its gel, are usually used as lithium ion electrolytes due to their ionic conductivity and voltage resistance. However, since gel and liquids are flammable, it is necessary to switch to safer polymer solid electrolytes.

Polymer solid electrolytes, such as polyethylene glycol (PEG), have been recommended as shock resistant lithium ion electrolytes. However, PEG based polymer electrolytes tend to crystallize near room temperature, resulting in a sharp drop in lithium ion conductivity to about 10-6 S/cm.

In order to solve this problem, the research team designed a new type of polymer solid electrolyte, which integrates porous polymer membrane with many micro pores and PEG based polymer electrolyte that can be photocrosslinked.

The polymer solid electrolyte has realized a wide potential window (4.7 V), a high lithium ion migration number (0.39) and a high lithium ion conductivity of 10-4 S/cm group, which is equivalent to the liquid and sufficient to meet the use of the real world.

Due to natural diffusion, lithium ions moving in the electrolyte move in different directions. This distance ranges from many µ m to 10 µ m, and does not always move linearly between electrodes, which is one of the reasons for the drop in ionic conductivity.

Therefore, in the current research, by combining the photocrosslinking PEG based solid polymer electrolyte with the micron scale porous membrane, its working ability can be enhanced.

This polymer solid electrolyte shows its high performance as an electrolyte and its effectiveness in preventing the development of lithium dendrites (dendrites). Due to the addition of porous membranes, lithium dendrites will cause ignition. Achieving safe, high-performance lithium-ion batteries will help build sustainable energy supplies.