DC08 - Stockholm University - Sweden

Title: Nanoporous functional ionic separators for Na-ion batteries

Objective:

DC8 will synthesize functional nanoporous separators for Na-ion batteries by controlled wet-chemical method, focusing on facile and up-scalable preparation. Resulting separators will exploit electrostatic complexation between a cationic poly(ionic liquid) and a polyacid-based polyanion, simultaneously integrating the membrane formation and nanopore creation processes into a single and rather simple solution-soaking procedure. The polymer skeleton will guarantee the chemical and mechanical stability of membranes in Na-ion batteries. The nitrile functionality in the poly(ionic liquid) will be further covalently cross-linked via a mild base-catalyzed trimerization reaction to improve (electro)chemical stability. After a comprehensive and in-depth analysis of the structure-property relationship with respect to wettability, and the impact of porosity, morphology and tortuosity on the effective conductivity in the presence of liquid electrolyte, the best performing separators will be up-scaled to produce quantities sufficient for their implementation in Na-ion pouch cells.

Expected results:

DC8 will obtain a series of functional nanoporous separators from polyelectrolyte membranes using a facile and upscalable wet-chemical process and having tailored and enhanced properties (e.g. thickness < 25 μm, porosity > 50 %, tensile strength-MD >100 MPa, TD >10 MPa, high liquid electrolyte wettability, enhanced effective conductivity (i.e. reduced membrane tortuosity) and (electro)chemical stability enabling increased cyclability of Na-ion cells. The corresponding structure-property correlations between membrane structure (polymer chemical structure, pores size, pores surface functionality and charge) and electrochemical performance in Na-ion batteries (reduction of the impedance, enhanced effective conductivity, rate capability and cycle life) will be established and used as a guideline for further optimisation of separators functional properties. Na-ion cells (up to 100 mAh in pouch) will be assembled using scaled-up nanoporous separators (i.e. 1 m2) in collaboration with CSIC and KIT.

The selection process for this position is closed.

SUPERVISORS

Prof. Jiayin Yuan
Prof. Aji Mathew
Politecnico di Torino, Italy
Spanish National Research Council, Bellaterra, Spain
Cellfion, Stockholm, Sweden

Institutionen för material- och miljökemi, Stockholms universitet
Svante Arrhenius väg 16C, 114 18 Stockholm, Sweden