On January 14th , a research paper entitled Single Lithium-Ion Conducting Polymer Electrolytes Based on a Super-Delocalized Polyanion, composed by the research group led by Professor Zhou Zhibin and Professor Nie Jin at the School of Chemistry and Chemical Engineering, was published on Angrew. Chem. Int. Ed.,(55,2521-2525 IF:11.3),a top international journal in Chemistry.

To address the current problems associated with single lithium-ion conducting solid polymer electrolytes (SPEs) in  low ionic conductivity, which hinders its application into rechargeable lithium batteries and in the ambient temperature region Lithium batteries, the researchers elegantly propose a super-conjugate structure of perfluorinated sulfonimide anion with super-delocalized negative charge distribution and high flexibility, through introducing the functional group of electron-withdrawing perfluoralkyl sulfonimino group  into the classic sulfonimide anion. This significantly enhances the disassociation ability of lithium ions and promotes the motion of polymer chain, thereby significantly enhancing the ionic conductivity of the single Li-ion conducting SPEs. Li-ion conductivity of the SPE prepared is as high as 10(-4)s/cm at 70℃, which is among those with the highest Li-ion conductivity reported so far and comparable with the classic ambipolar LiTFSI/PEO SPEs in terms of Li-ion conductivity.

Thanks to the advantages bestowed by solid polymer electrolytes (SPEs), such as high safety, excellent mechanical flexibility, easy processing, as well as functions as both electrolytes and  separator, researches on the basic science and applied technology in the arena of all-solid-state lithium polymer batteries have been carried out worldwide over the past 30 years, in the hope of ultimately resolving the safety issues in state-of-art Li-ion batteries based on organic liquid electrolytes. Recently, great breakthroughs have made in the application of lithium polymer batteries. Since 2011, recycled solid polymer lithium batteries have been applied as power source to over 4000 Autolibs (an electric car sharing service based in Paris at the first phase of application) electric automobiles in demonstrative operations in France, German and Singapore. However, the solid polymer electrolytes (SPEs) being used are double ionic conductors, in which the anions that does not contribute to the electrochemical storage and conversion is mobile. During the discharge of battery, the transportation of anion results in concentration gradients of the salt and cell polarization, finally causing premature battery failure. It is well understood that one of the best solutions to the above-mentioned problem is to immobilize the anions through polymerization reaction so as to achieve the single Li-ion conducting solid polymer electrolytes. It is one of the hot research areas for the next-generation solid lithium battery technology.

The paper was lead-authored by Ma Qiang, a Grade 2014 Ph.D student, with the joint effort of Professor Hu Yongsheng, researcher from the Institute of Physics of CAS (Chinese Academy of Sciences) and Professor Michel Armand from the European Energy Research Center, Spain.

In fact, over the 20 years’ dedication to the research on the methodology of efficient fluorination and its application in the preparation of the electrolyte material for Li battery, research group led by Professor Zhou Zhibin and Professor Nie Jin have achieved promising results in the field of lithium salt electrolyte materials, arousing the interest and applauding of Li battery industry.

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