Pukyong National University

Contrarian research for 'securing additional capacity with explosive hazardous material in secondary batteries'

Professor Ko Min-Seong

Contrarian research that can secure additional battery capacity by using a material known as the main cause of fire or explosion of secondary batteries is attracting attention.

Pukyong National University announced that in case of overcharging exceeding the capacity of the graphite anode by leading the growth of defective carbon-nanotubes in the graphite anode, Prof. Ko Min-Seong (dept. of metallurgical engineering)'s team conducted research to effectively control the lithium formed on the graphite surface and utilize this as a battery capacity.

In addition to the disadvantage that the graphite anode material of the secondary battery has a low capacity, the formation of dendrite lithium on the graphite surface has been raised as a problem when overcharged or non-uniformly charged continuously. It is known that dendrite lithium causes deterioration of battery performance because of its low reversibility, and is known to be a major cause of deterioration of battery safety due to the risk of fire or explosion due to electric short circuit when continuously growing.

Professor Ko Min-Seong's research team conducted joint research with Dr. Sung Jae-Kyung from the Massachusetts institute of technology (MIT) and Dr. Kim Nam-Hyung from Pacific Northwest National Laboratory (PNNL) to find a way to overcome the capacity limit of graphite anode materials with dendrite lithium, which threatens the stability of the battery. Their research turned flaws into strengths.

The research team promoted the growth of carbon nanotubes with structural defects on the graphite surface by using a chemical vapor deposition process using a nickel catalyst and hydrocarbon gas. When this material was applied to the negative electrode, the research team confirmed that the lithium deposition was uniformly induced as the resistance of the electrode caused by the electrodeposition of lithium was alleviated.

As a result of the experiment, it was found that the uniform lithium layer induced in this way showed high reversibility and operated with additional battery capacity. When driving a full cell in which the capacity of the positive electrode was designed to be larger than that of the negative electrode, the reversible capacity could be used even after 300 cycles.

Professor Ko said, "I expect that defective carbon nanotubes can effectively control dendrite lithium to solve the battery stability problem, thereby reducing the unnecessary use of negative electrodes in electrode design, and at the same time improving battery energy density by using additional lithium."

The research was supported by the Korea evaluation institute of industrial technology (KEIT) and National Research Foundation of Korea (NRF), and was recently published in <Journal of Materials Chemistry A> (IF=12.732), an international academic journal in the field of materials and energy.