Publikationen

Uncontrollable dendrite growth and parasitic reactions are the fundamental obstacles to achieve large-scale application of aqueous Zn-ion batteries. Herein, a new strategy of tuning the electrolyte solvation structure and electrode interface is demonstrated for highly reversible zinc plating/stripping. Acetonitrile (AN) is introduced into Zn(OTf)2 electrolyte as co-solvent, the interaction between Zn2+ and acetonitrile attenuates the Zn2+ solvation and water activity. Concomitantly, theoretical calculations demonstrate that acetonitrile molecules tend to adsorb on the surface of zinc electrode to form an adaptive zinc-electrolyte interface. Such an electrolyte engineering significantly prevents water hydrogen evolution, suppresses vanadium dissolution and modulates Zn deposition behavior. As proof of concept, Zn//Zn symmetric cells with acetonitrile additive exhibit a ultra-long cycling of 2100 h at a high current density of 5 mA cm^-2. In particular, the university of the acetonitrile-water co-solvent (AWCS) electrolyte is demonstrated, multiple battery systems (Zn//Al-V-O, Zn//Zn-V-O, Zn//VOOH, and Zn//Mn-V-O) deliver markedly improved cycling stability and rate performance. The mechanism of action of AWCS electrolyte on performance indicators is discussed in detail, which provides a promising insight for energy storage devices.

Hierarchical assemblies of functional polymer particles are promising due to their surface as well as physicochemical properties. However, hierarchical composites are complex and challenging to form due to the many steps necessary for integrating different components into one system. Highly structured four-level composite particles were formed in a four-step process. First of all, gold (Au) nanoparticles, poly(methyl methacrylate) (PMMA) nanoparticles, and poly(tripropylene glycol diacrylate) (poly-TPGDA) microparticles were individually synthesized. By applying microfluidic techniques, polymer nano- and microparticles were formed with tunable size and surface properties. Afterwards, the negatively charged gold nanoparticles and PMMA particles functionalized with a positively charged surface were mixed to form Au/PMMA assemblies. The Au/PMMA composites were mixed and incubated with poly-TPGDA microparticles to form ternary Au/PMMA/poly-TPGDA assemblies. For the formation of composite-containing microparticles, Au/PMMA/poly-TPGDA composites were dispersed in an aqueous acrylamide-methylenebisacrylamide solution. Monomer droplets were formed in a co-flow microfluidic device and photopolymerized by UV light. In this way, hierarchically structured four-level composites consisting of four different size ranges - 0.025/0.8/30/1000 μm - were obtained. By functionalizing polymer nano- and microparticles with different fluorescent dyes, it was possible to visualize the same composite particle under two different excitation modes (λex = 395-440 and λex = 510-560 nm). The Au/PMMA/poly-TPGDA composite-embedded polyacrylamide microparticles can be potentially used as a model for the creation of composite particles for sensing, catalysis, multilabeling, and biomedical applications.

Rechargeable Na-CO2 batteries are promising energy-storage devices due to their high energy density, environmental friendliness, and cost effectiveness. However, the insulating nature and irreversibility of the Na2CO3 discharge product cause large polarization and poor cyclicity. Here, we report a reversible quasi-solid-state Na-CO2 battery that is constructed by the synergistic action of a Co-encapsulated N-doped carbon framework catalyst and gel electrolyte to ensure the formation of a highly reversible Na2C2O4 discharge product. Experiments and density functional theory calculations indicate that the electron-agglomeration effect of Co nanoparticles enhances CO2 adsorption and lowers energy barrier, as well as promotes Na2C2O4 generation. A gel electrolyte containing an imidazole organic cation is used to inhibit the decomposition of the thermodynamically unstable Na2C2O4. The fabricated Na-CO2 battery exhibits a high discharge capacity of 3,094 mAh g^-1, a high-rate performance of 1,777 mAh g^-1 at a current density of 0.5 mA cm^-2, and excellent cycling performance of 366 cycles (2,200 h).

The radical anion of Pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile (PPDN) in blends with imidazolium based room temperature ionic liquids (RTIL): EMIM-DCA, BMIM-BF4, EMIM-Ac has been detected by X-band continues wave (CW) electron paramagnetic resonance (EPR) under steady state Xe-lamp illumination in the temperature interval from 190 to 340 K. The radical anion of 1,4,5,8-Naphthalenetetracarboxylic dianhydride (NTCDA) was registered by X- and K-band CW EPR at room temperature under the visible light CW diode laser operated at 532 nm, and Xe-lamp as well. The experimental hyperfine coupling data of both anion radicals were confirmed by DFT calculation. The formation of PPDN•- NTCDA•- and fullerene derivative (FD) radical anions is attributed to the photoelectron transfer from an IL anion to PPDN, NTCDA and FD electron acceptors. Here, the electron transfer leads to an irreversibility of these reactions due to photo-induced decomposition of the IL anions in the presence of an effective electron acceptor and is supported in the above RTILs solutions by means of EPR. For the indirect confirmation of the EMIM-DCA, EMIM-AC, BMIM-BF4 anion degradation in solutions with PPDN and NTCDA up to the transient radical state, similar data of acetate anion [OCOCH3]- decomposition, under CW Xe-Lamp photolysis resulting in •CH3 formation and its stabilization at 77 K in EMIM-Ac suspension with some FD dissolved in DCB are introduced as well. However, the main goal of this study is dedicated to the features of rotational and translational diffusion kinetics of PPDN and NTCDA radical anions in IL solutions as well to the evaluation of their application as a spin probes in ILs study in liquid phase.