Polymeric artificial interfaces for next generation batteries

Modern day Li-ion batteries have countless interfaces (or interphases) and stability of these interfaces determines overall performance and durability of the final electrochemical devices. This is especially true for Li metal anode which is reactive towards most available/promising electrolytes (solid/liquid) but have the potential to provide extremely high capacity (> 1000 Wh/L). Li reacts immediately with most battery electrolyte components to form a passivation layer called solid electrolyte interphase (SEI), which is Li⁺ conducting and e^- insulating. However, this native SEI is not robust enough to prevent Li dendrites, and eventually leads to dead Lithium, which can ultimately result in cell failure. In this regard, an artificially engineered SEI with desired properties is a promising route to prevent dendrite formation and growth. An artificial interface layer can be of either inorganic or organic origin, but synthetic flexibility in organics is more convenient for creating a variety of molecular architectures. In addition, compared to small organic molecules, which might have limited electrochemical stability and issue of dissolution, strategically designed functional polymeric structures are promising for interfacial engineering on Li anode. Self-healing polymers based on molecular interdiffusion, or dynamic covalent bonding are well suited in this regard. The challenge will be to combine such self-healing properties along with stability towards Lithium, decent Li⁺ ion conductivity at ambient temperature, good tensile strength to mitigate Li dendrites, and sufficient elasticity to accommodate the constant volume change during plating/striping cycles.

 At imec, we are working on different strategies to stabilize Li metal anode towards both liquid as well as with solid electrolytes through multilayer stack architectures using both organic and inorganic layers. We have several years of experience in plating smooth and structured Li from optimized electrolyte baths, cell fabrication (coin cells, pouch cells) in glove box as well as in state-of-art dry rooms. For interfacial engineering, we are supported by our team’s expertise in thin film deposition, enabling us to deposit nanometer thick protective layers of inorganic/organic materials. In this project you will study various multilayer stacks for Li plating/stripping focusing on Li⁺ conductivity, uniform Li growth and stable cycling. You will work on design principles for artificial SEI layers, their fabrication through various routes including thin film deposition, chemical and electrochemical techniques. You will be working in a team together with other PhD students, researchers, and engineers, while collaborating with several different universities, research institutes, and companies. Your efforts will form the basis of successful fabrication of next generation Li – metal batteries.