Molecularly imprinted polymers have in recent times been attracting widespread interest especially arising from their application in the development of tools for organic synthesis as a result of their high specificity, easy availability, stability and low cost. These synthetic polymers are fabricated by polymerizing polymerizable reagents in the presence of a template. More so, these molecularly imprinted polymers have the capability to selectively reorganize and bind target molecules with tailor made molecular recognition binding sites. With such binding capabilities, molecularly imprinted polymers have been widely applied in catalysis, analytical chemistry, water treatment, sensors and biochemistry field.
However, their potential can still be tapped by constructing different binding sites which would in turn yield new applications. Consequently, the mutual demand for clean energy from modern industries inclusive of military power supplies, civil transportation and stationary storage have placed urgent demands on the energy density of the battery. Lithium-sulfur batteries have been considered promising for powering portable electronics because they have an overwhelming advantage in energy density.
Prof. Chenglin Yan and colleagues from Soochow University in China proposed a breakthrough study on the adaptability of molecularly imprinted polymers to enable high efficiency recognition and trapping of lithium polysulfides for the development of stable lithium-sulfur battery. The researchers aimed at exploiting the ability of the molecularly imprinted polymers to recognize and target specific molecules. Their research work is now published in Nano Letters.
The researchers commenced their empirical procedure by preparing molecularly imprinted polymers with Lithium-Sulphur recognition characteristics by polymerization of acrylamide monomer molecular with tetraglyme catholyte as the target template. Polymerization by initiation at 700C with azodiisobutyronitrile as the initiator was then effected. Eventually, the removal of template molecule by anhydrous dimethylformamide washing and cyclic voltammetry scans, that left featured binding sites in the polymer matrix was done.
The research team observed that the approached they used, permitted them achieve a high capacity retention of over 82% after just 400 cycles at one coulomb. They also noted that the UV/vis spectroscopy revealed low concentrations of tetraglyme catholyte in the electrolyte indicating that the molecularly imprinted polymers matrix has excellent ionic sieving ability to tetraglyme catholyte during electrochemical cycle. More so, the visual characterization gave direct evidence on the affinity and absorbability of molecularly imprinted polymers to tetraglyme catholyte, which was theoretically confirmed by density functional theory calculations.
Herein, a new strategy of using molecularly imprinted polymers as recognition sites for polysulfides in Lithium-Sulphur battery system so as to trap long chain polysulfides, has been brought forward. Acrylamide and tetraglyme catholyte molecule have been employed as functional monomer and template, respectively, for the construction of molecularly imprinted polymers material, which can constraint tetraglyme catholyte in the molecularly imprinted polymers matrix by rebinding the target molecules. Undoubtedly, the original design demonstrated here opens a new direction of the electrochemical application of molecularly imprinted polymers materials in Lithium−Sulphur batteries.
Jie Liu, Tao Qian, Mengfan Wang, Xuejun Liu, Na Xu, Yizhou You, and Chenglin Yan. Molecularly Imprinted Polymer Enables High-Efficiency Recognition and Trapping Lithium Polysulfides for Stable Lithium Sulfur Battery. Nano letters 2017, volume 17, pages 5064−5070.Go To Nano Letters