As part of the Department of Chemical and Materials Engineering PhD Seminar Series, Dr. Michel Armand, innovator in lithium-ion and solid state batteries, will deliver a lecture discussing the latest developments in the field.
The climate drama calls for unprecedented changes in particular in the way we use and store energy. Both transportation EVs and grid storage are needed to abate the CO2 emissions. Batteries are seen as a solution for this purpose. However, today’s Li-ion batteries do not meet the requirement of safety and sustainability, with flammable organic solvent and a weaning from rare cobalt for electrode materials more difficult than anticipated. Solid-state batteries that can harness a lithium metal operation could give higher energy density, or keep them on a par despite using the lower voltage but earth-abundant LiFePO4. Polymer electrolytes batteries are already a reality powering EVs, busses, and are used in Africa for solar energy storage . The only drawback of such batteries, which are relatively safe despite the use of Li metal, is their operating temperature of ≈ 70°C needed to reach the desired conductivity. Besides, the fraction of the current carried by Li+ is only ≈ 20% of the total current, anions being more mobile. In this presentation, we will show how the modification of the architecture of the polymer, keeping the same solvating units, can help bring down the temperature of operation, though not yet to RT. New solutes (salts) have been designed so that the corresponding anions less mobile in the matrix, increasing the fraction of the current carried by Li+ . Modification of the wellknown anion TFSI to increase its interactions and slow it down have been undertaken: either hydrogen bonds, dipole interactions, chain entanglement, or π - π interactions have been introduced in the RSO2N(- )SO2CF3 anion with R equal respectively CF2H—, (CH3)2N—, (CH3OC2H4)2N—, C6H5—. In all cases, higher T+ were obtained as compared with TFSI-, though the total conductivity was lower, but resulting still in σLi+ that translates into better lithium plating efficiencies as seen in the classical Li°/PE/Li° cells. The resulting progress will be discussed.
About Dr. Michel Armand
Prof. Dr. Michel Armand received his Ph.D. from University Joseph Fourier (1978). He was Director for Research at Centre National de la Recherche Scientifique (CNRS, France) since 1989 and Professor at University of Montreal (1995−2004). He has ushered theoretical concepts leading to practical applications in energy-related electrochemistry. He has been one of the pioneers of the use of intercalation electrodes (1972), of the introduction of the polymer electrolytes for battery application (1978), of new salts based on delocalized anions, of the sulfonimide family (1986), of organic electrode materials (1996) and of the carbon coating for electrode materials like LiFePO4. He joined CIC Energigune in 2013, and present activities include new solvating polymers for lithium and sodium, new salts and nitrogen-containing electrode materials; Michel Armand has been quoted > 85000 times and has a H factor of 95.