From left, Prof.Park Su-jin of POSTECH, Dr. Woo-Jin Song of POSTECH, Dr. Myeong-Soo Shin of UNIST, Prof. Yoo Seung-min of Ulsan University, Prof. Nam-Soon Choi of UNIST, Dr. Jung-gu Han of UNIST. © News 1

 A membrane based on an agar developed by a collaborative research team. (Presented by Prof. Nam-Soon Choi, UNIST) © News 1

 Degradation results in shorter battery life and lower efficiency of batteries. POSTECH said it has developed a technology that suppresses the deterioration of secondary batteries, which continue to charge and discharge, such as electric cars and smart phones, by professor Park Soo-jin, Dr. Woo-Jin Kim.

The research team solved the problem of battery deterioration by using an agar, which is mainly used as a raw material of jelly.
An organic electrolyte-based lithium secondary battery has a problem that an electrolyte is eluted by attacking a cathode material at a high temperature.

Therefore, high-voltage, high-capacity lithium secondary batteries were not able to perform at high temperatures and were regarded as the biggest obstacle to the commercialization of electric vehicles. The researchers paid attention to the hydrophilicity of agar in order to solve the deterioration phenomenon.

Agar, a natural seaweed, is a food that can be eaten in a summer soybean paste soup. When agar is mixed with water, agar is tangled like a jelly and has a property of holding water.

To utilize the properties of agar, the team developed polymer membranes with uniform pores by reacting organosilicon compounds to control the hydrophilicity of the agar and phase separation. The membrane thus formed showed flexibility and maintains the porous structure without thermal deformation at high temperature.

Professor Park said, “Applying multi-functional membranes and binders made from agar to high performance cells will not cause a big problem in battery operation even at high temperatures.”