Research Field 4

Katcharava, Z. et. al., Chemistry- An European Journal., 2024, 30, e202402004, https://doi.org/10.1002/chem.202402004

 Novel fluorinated, pyrrolidinium-based dicationic ionic liquids (FDILs) as high-performance electrolytes in energy storage devices have been prepared, displaying unprecedented electrochemical stabilities (up to 7 V); thermal stability (up to 370 °C) and ion transport (up to 1.45 mS cm−1). FDILs were designed with a fluorinated ether linker and paired with TFSI/FSI counterions. To comprehensively assess the impact of the fluorinated spacer on their electrochemical, thermal, and physico-chemical properties, a comparison with their non-fluorinated counterparts was conducted. With a specific focus on their application as electrolytes in next-generation high-voltage lithium-ion batteries, the impact of the Li-salt on the characteristics of dicationic ILs was systematically evaluated. The incorporation of a fluorinated linker demonstrates significantly superior properties compared to their non-fluorinated counterparts, presenting a promising alternative towards next-generation high-voltage energy storage systems. © 2024 The Authors. Chemistry – A European Journal published by Wiley-VCH GmbH

Katcharava, Z. et. al., Advanced Functional Materials, 2024, 2403487,  https://doi.org/10.1002/adfm.202403487

Here, poly(ionic liquid)-based dual network gel electrolytes are reported as safer and sustainable alternative materials for next-generation energy storage systems. The materials employ both, dynamic (up to 45 mol%) and covalent crosslinking (up to 10 mol%), allowing the fabrication of mechanically stable gels with a high content (up to 65 wt%) of ionic liquid/salt both via thermal and photo polymerization. The dual nature of this network in interplay with other key components is systematically investigated. Mechanical stability (up to 0.7 MPa), combined with enhanced ionic conductivity (surpassing 10⁻⁴ S cm⁻¹ at room temperature) is achieved via the synergetic combination of dynamic non-covalent and covalent crosslinking, resulting in improved electrochemical (up to 5 V) and thermal stability (reaching 300 °C) by the embedded ionic liquid. Moreover the presence of the dynamic crosslinks facilitates reprocessing at 70 °C without comrpomising the electrochemical performance, thus reaching full recyclability and reusability. © 2024 The Author(s). Advanced Functional Materials published by Wiley‐VCH GmbH.

Li, C. et. al., Macromol. Raid Commun., 2023,  2300464,  https://doi.org/10.1002/marc.202300464 

Hydrogen bonds (H-bonds) are highly sensitive to the surrounding environments owing to their dipolar nature, with polar solvents kown to significantly weaken H-bonds. Herein, the stability of the H-bonding motif ureidopyrimidinone (UPy) is investigated, embedded into a highly polar polymeric ionic liquid (PIL) consisting of pendant pyrrolidinium bis(trifluoromethylsulfonyl)imide (IL) moieties, to study the influence of such ionic environments on the UPy H-bonds. The content of the surrounding IL is changed by addition of an additional low molecular weight IL to further boost the IL content around the UPy moieties in molar ratios of UPy/IL ranging from 1/4 up to 1/113, thereby promoting the polar microenvironment around the UPy-H-bonds. Variable-temperature solid-state MAS NMR spectroscopy and FT-IR spectroscopy demonstrate that the UPy H-bonds are largely present as (UPy-) dimers, but sensitive to elevated temperatures (>70 °C). Subsequent rheology and DSC studies reveal that the ILs only solvate the polymeric chains but do not interfere with the UPy-dimer H-bonds, thus accounting for their high stability and applicability in many material systems. © 2023 The Authors. Macromolecular Rapid Communications published by Wiley‐VCH GmbH

Katcharava, Z. et al., RSC Advances, 2023, 14435-14442,

https://doi.org/10.1039/D3RA02396F

Polymer electrolytes (PEs) are a promising alternative to overcome shortcomings of conventional lithium ion batteries (LiBs) and make them safer for users. Introduction of self-healing features in PEs additionally leads to prolonged life-time of LIBs, thus tackling cost and environmental issues. We here present solvent free, self-healable, reprocessable, thermally stable, conductive poly(ionic liquid) (PIL) consisting of pyrrolidinium-based repeating units. The dynamic boronic ester linkages allow reprocessing (at 40 °C), reshaping and self-healing ability of PEs. Such vitrimeric PILs rcan be subjected to 3D printing via FDM, offering the possibility to design batteries with more complex and diverse architectures. Published with a permission of the Royal Society of Chemistry 2023.

Li, C. et al., Polymers, 2022, 4090,

https://doi.org/10.3390/polym14194090

Within the era of battery technology, the urgent demand for improved and safer electrolytes is immanent. In this work, novel electrolytes, based on pyrrolidinium-bistrifluoromethanesulfonyl-imide polymeric ionic liquids (POILs), equipped with quadrupolar hydrogen-bonding moieties of ureido-pyrimidinone (UPy) to mediate self-healing properties were generated. By combining the results from differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS), and rheology, a decoupled conductivity of the POILs from the glass transition was revealed. Tensile tests for both pristine and self-healed samples, evidenced a rational design of self-healing electrolytes bearing both hydrogen bonding moieties and low-molecular-weight polymeric ionic liquids.

Zhou, X. et al., ACS Applied Engineering Materials, 2023, accepted,

https://doi.org/10.1021/acsaenm.3c00286

Vitrimers have been widely employed in self-healing, recyclable, and shape-shifting materials. However, the application of catalyst-free vitrimers to create self-healable and mechanically robust gel polymer electrolytes (GPEs) remains a challenge, often limiting the potential of vitrimer-based materials. Herein, we utilized a catalyst-free dynamic covalent bond (silyl ether) as a linkage to prepare self-healable and mechanically robust GPEs, which are fully reprocessable. By incorporating polymeric ionic liquids into the dynamically cross-linked networks, both ion conductivity and mechanical properties can be flexibly tuned. This dynamic feature enables self-healing and allows for reprocessing via embedding of such dynamic covalent networks into the GPEs, exhibiting good ion conductivites of 0.13 mS/cm at 20 °C and 1.88 mS/cm at 80 °C. Furthermore, the elastic modulus of the GPEs could reach a value of 0.24 MPa and was able to persist through electrode-volume expansions during charging/discharging, indicating promising applications for this type of dynamic bond in sustainable solid electrolytes. Copyright © 2023, American Chemical Society.

Katcharava, Z. et al., RSC Advances, 2023, 14435-14442,

https://doi.org/10.1039/D3RA02396F

Polymer electrolytes (PEs) are a promising alternative to overcome shortcomings of conventional lithium ion batteries (LiBs) and make them safer for users. Introduction of self-healing features in PEs additionally leads to prolonged life-time of LIBs, thus tackling cost and environmental issues. We here present solvent free, self-healable, reprocessable, thermally stable, conductive poly(ionic liquid) (PIL) consisting of pyrrolidinium-based repeating units. The dynamic boronic ester linkages allow reprocessing (at 40 °C), reshaping and self-healing ability of PEs. Such vitrimeric PILs rcan be subjected to 3D printing via FDM, offering the possibility to design batteries with more complex and diverse architectures. Published with a permission of the Royal Society of Chemistry 2023.

Marinow, A. et al., Polymers, 2023, 1145,

https://doi.org/10.3390/polym15051145

The integration of polymer materials with self-healing features into advanced lithium batteries is a promising and attractive approach to mitigate degradation and, thus, improve the performance and reliability of batteries. This paper comprehensively reviews various categories of self-healing polymer materials for application as electrolytes and adaptive coatings for electrodes in lithium-ion (LIBs) and lithium metal batteries (LMBs). We discuss the opportunities and current challenges in the development of self-healable polymeric materials for lithium batteries in terms of their synthesis, characterization and underlying self-healing mechanism, as well as performance, validation and optimization.

Chenming Li , et al. Polymers, 2022, 14, 4090, DOI:https://doi.org/10.3390/polym14194090

Within the era of battery technology, the urgent demand for improved and safer electrolytes is immanent. In this work, novel electrolytes, based on pyrrolidinium-bistrifluoromethanesulfonyl-imide polymeric ionic liquids (POILs), equipped with quadrupolar hydrogen-bonding moieties of ureido-pyrimidinone (UPy) to mediate self-healing properties are generated. The polymers display good conductivities as well as a self-healing efficiency of up to 88 %, in turn evidencing a rational design of self-healing electrolytes bearing, both hydrogen bonding moieties and low-molecular-weight polymeric ionic liquids.

Katacharava, Z., et al. Nanomaterials 2022, DOI:https://doi.org/10.3390/nano12111859

We here demonstrate the preparation of composite polymer electrolytes (CPEs) for Li-ion batteries, applicable for 3D printing process via fused deposition modeling. Based on composites of modified (H-bonding) poly(ethylene glycol) (PEG), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and SiO2-based nanofillers we introduce self-healing into the electrolyte system. The composite electrolyte PEG 1500 UPy2/LiTFSI (EO:Li 5:1) mixed with 15% NP-IL was successfully 3D printed, revealing its suitability for application as printable composite electrolyte.