Printable Electrolytes: Tuning 3D‐Printing by Multiple Hydrogen Bonds and Added Inorganic Lithium‐Salts

• Published in: Advanced materials technologies 2022-08, Vol.7 (8), p.n/a
• Main Authors: Rupp, Harald, Bhandary, Rajesh, Kulkarni, Amit, Binder, Wolfgang
• Format: Article
• Language: English
• Subjects: 3D‐printing; battery; conductivity; electrolyte; hydrogen bonds
• ISSN: 2365-709X; 2365-709X
• DOI: 10.1002/admt.202200088

Here, the 3D‐printing of supramolecular polymer electrolytes is reported, able to be manufactured via 3D‐printing processes, additionally dynamically compensating for volume changes. A careful mechanical design, in addition to rheological effects observed for different additives to the electrolyte, is investigated and adjusted, in order to achieve printability via an extrusion process to generate a conductive electrode material. Qudruple‐hydrogen bonds (UPy) act as supramolecular entities for the desired dynamic properties to adjust printability, in addition to added LiTFSi‐salts to achieve ionic conductivities of ≈10–4 S cm–1 at T = 80 °C. Three different telechelic UPy‐PEO/PPO‐UPy‐polymers with molecular weights ranging from Mn = 600–1500 g mol−1 were investigated in view of their 3D‐printability by FDM‐processes. It is found that there are three effects counterbalancing the rheological properties of the polymers: besides temperatures, which can be used as a known tool to adjust melt‐rheology, also the addition of lithium‐salts in junction with the polymers crystallinity exerts a major toolbox to 3D‐print these electrolytes. Using specific compositions with Li/EO‐ratios from 20:1, 10:1, and 5:1, the rheological profile can be adjusted to reach the required printability window. AT‐IR‐investigations clearly indicate a weakening of the UPy‐bonds by the added Li+ ions, in addition to a reduction of the crystallinity of the PEO‐units, further changing the rheological profile. The so generated electrolytes are printable systems for novel electrolytes. 3D printing of novel supramolecular polymer electrolytes, additionally compensating for volume changes is reported. UPy‐PEO/PPO‐UPy‐polymers bearing quadruple‐hydrogen bonds, in mixture with Li/EO ranging from 20:1, 10:1, and 5:1 enable printability and ionic conductivities of ≈10‐4 S cm‐1 at T = 80 °C. AT‐IR‐investigations indicate weakening of the UPy‐bonds by the addition of Li+ ions and a reduction of the PEO's crystallinity.