According to foreign media reports, a South Korean research team successfully developed a new generation of high-capacity cathode materials for lithium ion batteries. The Korean Academy of Science and Technology (Korea Institute of Science and Technology,KIST) announced that Dr. Kyung Yoon, head of the KIST energy storage center, and Professor Sang-Young Lee (National Weishan Academy of Science and Technology) and the joint research team composed of doctor Wonyoung Chang, the chief researcher of KIST pure center, successfully developed a kind of high-performance cathode material by using salmon DNA to stabilize over lithium layered oxide (OLO).
(Photo source: eurekalert.org)
In the lithium ion secondary battery, the number of lithium ions moving back and forth between the yin and yang poles during charging and discharging determines the energy density of the battery system. In other words, the research and development of high-capacity cathode materials is crucial to improving the capacity of lithium ion batteries.
The reversible capacity of over-lithium layered oxide is relatively high, reaching 250 mAh/g (the reversible capacity of the existing commercial materials is only 160 mAh/g), which has long been considered as a new generation cathode material, can improve the energy storage capacity of the battery by more than 50%. However, the main disadvantage of OLO is that during the charge and discharge cycle, the layered structure of OLO will collapse, resulting in expansion and eventually making the battery unusable.
The KIST research team divided the surface and interior of OLO into specific areas and analyzed the changes of the crystal structure by using a perspective electron microscope. The analysis structure shows that after repeated charge and discharge cycles, the metal layer on the surface of OLO begins to collapse.
Therefore, the joint research team adopted a salmon DNA with strong adsorption force on lithium ions to control the surface structure of OLO, which will lead to material degradation. However, the salmon DNA shows a trend of aggregation in aqueous solution. To solve this problem, the research team combined carbon nanotubes (CNT) and salmon DNA into composite coating materials. The DNA/CNT mixture was evenly placed and attached to the surface of OLO, thus a new cathode material was developed.
The KIST research team adopted comprehensive advanced analysis technology (studying various factors, from single particle to electrode) and found that the electrochemical characteristics of OLO and its structural stability mechanism have been improved. The results of in-situ X-ray analysis also confirmed that the structural degradation was inhibited and the thermal stability was improved during the charge-discharge cycle.
