Structure and Conductivity of Crosslinked Ca‐POE Polymer Electrolytes for Secondary Batteries

• Published in: ChemElectroChem 2024-10, Vol.11 (20), p.n/a
• Main Authors: Brombin, Federico, Pagot, Gioele, Vezzù, Keti, Roman, Raul San, Martinez Cisneros, Cynthia Susana, Ureña, Nieves, Varez, Alejandro, Sanchez, Jean‐Yves, Di Noto, Vito
• Format: Article
• Language: English
• Subjects: Anions; batteries; Broadband; broadband electrical spectroscopy; calcium electrolytes; Calcium ions; conductivity; Coordination; Coupled modes; Crosslinking; Electrical properties; Electrolytes; Mechanical properties; Metal ions; Molecular chains; Molecular weight; Molten salt electrolytes; polymer electrolytes; Polymers; Polyoxyethylene; Solid electrolytes; Spectroscopy; Storage batteries
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.202400315

Poly(oxyethylene) (POE) is frequently used as suitable component to prepare solid polymer electrolytes (SPEs), due to its: (i) ability to coordinate and dissociate doping salts; (ii) good mechanical properties; and (iii) high chemical and electrochemical stability. With the aim to obtain calcium secondary batteries, here we describe the preparation and studies of crosslinked Ca‐polycondensate (NPCY) electrolytes with formula NPCY/(CaTf2)x based on fragments of POE chains and CaTf2. The molecular weight of POE precursors is Y=400 and 1000 g ⋅ mol−1. The effect of POE molecular weight on the thermal, structural, and electrical properties of NPCY/(CaTf2)x is investigated revealing that in mesoscale this materials show: (i) two different nanodomains with polyether chains both “free” (not coordinating the cation) and involved in 4–4 coordination cages of Ca2+ metal ions; (ii) fα‐fast, fα‐cross and fα‐slow relaxation modes of polyether chains, detected by broadband electrical spectroscopy, which are coupled with the long‐range charge migration pathways of SPEs; (iii) that triflate (Tf−) anions, which act as plasticizers, modulate the inter‐chain migration processes of Ca2+ between polyether coordination sites. Finally, the conductivity values of NPCY/(CaTf2)x, which is up to 10−4 S ⋅ cm−1 at 80 °C, classify NPCY/(CaTf2)x as promising SPEs for the development of calcium secondary batteries. Crosslinked Ca‐polycondensate (NPCY) electrolytes, based on poly(oxyethylene) (POE) chains and CaTf2, exhibit nanodomains with polyether chains “free” and coordinating Ca2+ ions. The influence of POE molecular weight on thermal, structural, and electrical properties of electrolytes is studied. The electrolytes show promising conductivity values up to 10−4 S ⋅ cm−1 at 80 °C, making NPCY/(CaTf2)x as potential SPEs candidates for calcium secondary batteries.