No. 94

April 2014

Headline News Innovation and Development

Applied Technology

Basic Science

Cooperation between CAS and Local Authorities

Bioscience International Cooperation Brief News Geoscience Activities of CAS Leaders
Applied Technology

New Method to Increase Rice Draft Resistance

“An approach to increase drought stress tolerance of rice, Medicago and Bermudagrass through exogenous application of low concentration NaCl solution” won state Invention patent. Through the cooperation of Prof. Chan Zhulong and Dr. Shi Haitao from the Wuhan Botanic Garden, CAS, “An approach to increase drought stress tolerance of rice, Medicago and Bermudagrass through exogenous application of low concentration NaCl solution” was granted the Chinese Invention Patent (ZL201310096011.X) on Jan, 7, 2014. Drought is the most severe abiotic stress which greatly affects plant growth and development. In North and Northwest of China there is less rainfall for a whole year, while other areas in south of China also encounter seasonal drought without rainfall in several months. The patent provides an easy-going approach to increase drought stress tolerance of rice, Medicago and Bermudagrass in these areas when drought or seasonal drought happens. Through exogenous application of low concentration NaCl solution, plant tolerance to drought stress could be increased in a very short period. Compared with the non-treatment control, survival rate of rice, Medicago and Bermudagrass were increased 20-50% after NaCl solution treatment. And water consumption for plant irrigation decreased for up to 30%. This invention provides an effective and easy-operating approach to increase crop yields and grass biomass during drought season, which is useful and helpful for plant growing and ecosystem restoration.

Progress Made on High Energy/Density Lithium/Sulfur Cells

Since 2010, a research group at the Advanced Carbon Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, CAS made use of carbon materials with high electrical conductivity, good chemical and thermal stability, large surface area, rich surface chemistry to conquer the above-mentioned challenges. They designed and developed a series of high-performance carbon-sulfur composite cathode materials at nano-scale by confining sulfur in micropores, defects and surface active sites, which effectively improve the electrical conductivity and restrict the polysulfide dissolution. Most recently, the team designed a unique sandwich structure with pure sulfur between two graphene membranes. One graphene membrane was used as a current collector (GCC) to replace commercial Al foil with sulfur coated on it as active material, and the other graphene membrane was coated on a commercial polymer separator (G-separator). The flexible and conductive graphene layer on the sulfur electrode provides excellent electric conductivity, and the sandwich structure can accommodate the large volumetric expansion of sulfur during lithiation. The presence of the graphene layer on the separator surface acts as a good barrier to mitigate the shuttle effect of dissolved polysulfides. Furthermore, the surface roughness of the GCC can improve the adhesion of sulfur to it and lower the impedance and polarisation of the Li–S battery. These properties provide the Li-S batteries with long cycling life and excellent rate performance. This design avoids any surface modification of sulfur particles and simplifies the fabrication of sulfur cathode. Because the density of a GCC is only one quarter of that of an Al-foil current collector, the use of GCC can further improve the specific energy density when assembled into a battery. Furthermore, for the first time they used a three-dimensional X-ray microtomography to explore the sulphur distribution in the electrode after cycling. It should be noted that the graphene used in the research is produced through an intercalation-exfoliation method from graphite and is commercially available at low cost. These features give the design and materials strong potential for the industrial production and application of Li–S batteries. The related work was published in Adv. Mater., 2014, 26, 625–631 (selected as Back cover), ACS Nano, 2013, 7, 5367–5375, Energy Environ. Sci., 2012, 5, 8901–8906, and applied for three Chinese patents.

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