TOPIC 23 - Novel binders enabling carbon-free Si anodes for the next generation of Li-ion batteries

The traditional graphite-based Li-ion battery technology still falls short in meeting the target for most demanding applications, such as electric vehicles. An intense research effort is hence dedicated at increasing the capacity of the anode. Silicon has been identified as a promising alternative owing to its 10-fold larger capacity compared to graphite. However, this record capacity is associated with ca 400% volumetric change during the Si-Li alloying reaction. This huge variation of the active materials’ particle size induces mechanical disintegration of the electrode when prepared by the traditional slurry casting method. Moreover, such drastic volumetric change is a concern for the stability of the SEI, a thin organic passivation layer that forms at the first cycle which prevents further electrolyte decomposition. A non-stable SEI will also contribute to capacity fading. An intense research effort is hence dedicated at allowing Si
anode to be viable, typically through carbon-Si composite preparation. In this approach the carbon matrix is designed to cope with the volumetric change of Si without losing electrical and mechanical cohesion within the electrode. However, for the moment no more than 10% Si can be found in the Si-carbon anode of last generation commercial Li-ion cells, leading to a limited gain in terms of energy density. A different approach is proposed here to increase the Si content, based on the development of novel polymer binders.

CIC energiGUNE has a solid track record in the development of organic and polymer-based materials as additive, solid electrolyte as well as binder for Li-ion batteries. It is well equipped for the synthesis and characterization of organic materials (liquid- and solid-state NMR, IR, Raman, DCS, TGA, rheological analysis), and has a state-of-the-art electrochemical characterization lab. CIC energiGUNE has also extensive experience in the study of electrochemical reactivity and charge storage mechanisms, supported by the availability of lab-scale operando techniques such as operando XRD and operando SAXS.

The student will have the possibility to undertake a research stay within the team of Pr. Władysław Wieczorek at the Warsaw University of Technology (Poland), which is specialized in the synthesis of novel organic metal alkali salts and other electrolyte additives.