Researchers from the Institute for Basic Science (IBS) have developed a simple synthetic method for producing carbon-based hybrid cellular nanosheets that exhibit strong electrochemical performance for key aspects of high performance lithium-ion batteries anodes. The results were originally published in the September issue of the Journal of the American Chemical Society (JACS).

The nanosheets consist of closely packed cubic cavity cells separated by carbon walls, resembling the vascular tissue makeup of a leaf from its top and cross-sectional structure views. Nanosheets are incredibly thin, two-dimensional nanostructures with a thickness ranging from 10 to 100 nanometers (nm). Graphene, measuring 0.34nm, is perhaps the best known 2-D material in the world and holds immense properties. A human hair, in contrast, is about 100,000nm.

The team from the Center for Nanoparticle Research within IBS began their experiments by loading carbon cellular nanosheets with tin dioxide (SnO₂) nanoparticles. Using this as a base, they found the resulting anode material (positively charged electrode) showed a specific capacity of 914 mAh g^–1 on average, with a retention of 97.0% during 300 cycles. This is in stark contrast to that of graphite, 372 mAh/g^–1, which is a commercialized anode material. When the cycle density was increased from 200 to 3000 mA g^–1, the reversible capacity was decreased by only 20% from 941.3 to 745.5 mAh g^–1. Charging and discharging a lithium-ion battery involves moving lithium ions into and out of the anode. The more lithium the electrode can pack the more energy the battery can store.

The results of the experiments performed on the SnO₂−carbon nanosheets were compared with that of carbon cellular nanosheets and an SnO₂ nanosheet and found that their hybrid materials significantly outperformed the others. This performance can be compared with that of other similar structured hybrid nanostructures. For example, the team’s previous effort reported ferrite−carbon hybrid nanosheets, that exhibited a specific capacity of 600 mAh/g^–1 and 73% retention of initial capacity after 50 cycles.

According to the team, “the development of next-generation energy-storage devices is of primary importance to meet the challenges in the electronics and automobile industries in the near future. In particular, there has been increasing interest in the development of new multicomponent nanomaterials that can overcome a number of intrinsic limitations of single-component electrode materials for lithium-ion batteries.”

The results, published in JACS, show that effective hybrid nanostructured electrode material can be prepared via a relatively simple procedure. As many different kinds of materials can be immobilized in the carbon cellular nanosheets, the resulting hybrid cellular nanosheets can be applied to various areas including electrochemical devices and catalysis.

Figure 1. Illustration of a SnO₂ carbon hybrid cellular nanosheet and
its features that contribute to the electrochemical performance. Credit: ACS, Yu et al.

By Neil Mannix

Notes for editors

- References
Seung-Ho Yu, Dong Jun Lee, Mihyun Park, Soon Gu Kwon, Hyeon Seok Lee, Aihua Jin, Kug-Seung Lee, Ji Eun Lee, Myoung Hwan Oh, Kisuk Kang, Yung-Eun Sung and Taeghwan Hyeon, Hybrid Cellular Nanosheets for High-Performance Lithium-Ion Battery Anodes, JACS. DOI: 10.1021/jacs.5b03673

- Media Contact
For further information or to request media assistance, please contact: Mr. Shi Bo Shim, Head of Department of Communications, Institute for Basic Science (+82-42-878-8189; sibo@ibs.re.kr) or Ms. Sunny Kim, Department of Communications, Institute for Basic Science (+82-42-878-8135;Sunnykim@ibs.re.kr)

- About the Institute for Basic Science (IBS)
IBS was founded in 2011 by the government of the Republic of Korea with the sole purpose of driving forward the development of basic science in Korea It comprises a total of 50 research centers in all fields of basic science, including mathematics, physics, chemistry, life science, earth science and interdisciplinary science. IBS has launched 25 research centers as of October 2015.There are eight physics, one mathematics, six chemistry, eight life science, and two interdisciplinary research centers.