The research on aqueous zinc ion batteries (AZIB) is getting more attention as the energy transition continues to develop and the need for inexpensive and safe stationary storage batteries is growing. As the detailed reaction mechanisms are not conclusively revealed, we want to take an alternative approach to investigate the importance of pH value changes during cycling. By adding a pH-indicator to the electrolyte (2 M ZnSO 4 + 0.1 M MnSO 4 ), the local pH-value change during operation is visualized in operando. The overall pH value was found to increase during cycling whereas a major temporary pH drop in close proximity of the manganese dioxide electrode surface occurs. Additionally, this pH value change was quantified locally by in operando measurements with a pH micro electrode. Different electrolyte compositions with additives (sodium dodecyl sulfate (SDS), sulfuric acid (H 2 SO 4 )) and operation voltages were tested. The pH-potential-diagrams of manganese and zinc reveal pH value and potential limits, leading to active material dissolution at lower pH values and oxygen gas evolution at higher potentials >1.7 V. The procedure of combining a pH indicator, pH microelectrode measurements and pH-potential diagrams can be seen as an appropriate method to determine the recommendable working window of aqueous batteries.

A short synthesis route to silica‐encapsulated nanoparticles coated with a self‐assembled monolayer (SAM) is presented. The organic molecules within the SAM contain a SiO2 precursor to render the surface vitreophilic. Due to the high mechanical and chemical stability of a glass shell, such particles can be used as probes in targeted research with surface‐enhanced Raman scattering as the read‐out method.

The reaction mechanisms (RM) during cycling of aqueous rechargeable Zn//MnO2 batteries (ARZIBs) are still controversially discussed. The present study of different acidic electrolyte compositions (0.9 mM H2SO4, 0.5 M MnSO4, 2 M ZnSO4, 2 M ZnSO4+0.5 M MnSO4) and their pH behaviour is therefore designed as an alternative approach to investigate the RM. In operando pH tracking during cycling shows periodic pH changes for each electrolyte, highlighting the role of the pH‐relevant ions OH− and H+ in the chemical processes, the major influence of MnO2 deposition/dissolution mechanisms and the buffering behaviour of the zinc hydroxide sulphate (ZHS) precipitation. Innovative coupled cyclic voltammetry (CV) and pH measurements can link CV redox peaks to a pH change and a corresponding chemical reaction. It was found that a Zn2+ (de‐)intercalation has little or no influence on the capacity. The cycling of the SO42−‐free electrolyte 2 M Zn(CF3SO3)2 underlines the pH‐dependant behaviour of the chemical processes. The results can contribute to the debate of RMs in ARZIBs and other aqueous battery chemistries by introducing a novel measurement technique.

Gold oxide films were prepared by reactive sputtering of pure gold in an oxygen plasma. These films were characterized by chemical and physical means to better understand the behavior of this metastable compound. Gold oxide, Au2O3, decomposes into the elements at 350 °C. It does not react with dry carbon dioxide but does form a metastable bicarbonate in the presence of moisture and CO2, releasing oxygen and eventually reverting to elemental gold. Gold oxide was generated by reactive sputtering along with silica in an oxygen plasma from Au–Si solidified alloys. Gold oxide decomposed upon pyrolysis to produce composites showing different characteristics depending on the gold content. Composites containing about 95 wt % gold produced reflective, conductive, and adherent films. Composites derived from an alloy containing 5 at. % gold produced a nanostructured material with gold clusters of about 5 nm in diameter dispersed in a silica matrix. This nanocomposite showed high resistivity, and capacitance with a dielectric constant of 400.

In this work, lithium-ion battery full-cells based on sprucederived hard carbon anodes and an electrochemical prelithiation method are presented in combination with a detailed analysis of full-cell operation and the lithiation state. The physical and electrochemical properties agree well with those of previous biomass-derived hard carbon anodes. However, low initial coulombic efficiencies of 65 % represent one of the major challenges of the developed anodes with respect to full-cell operation. To counteract the initial lithium loss, in-situ electro-chemical pre-lithiation was conducted, allowing battery operation in the same cell setup without reassembly. Consequently, significantly increased capacities, cycle life, and first cycle coulombic efficiency were obtained in comparison to untreated anodes (195 mAh/g versus 150 mAh/g, state of health (SOH) 80 after 150 cycles versus 70 cycles, and 90 % versus 65 %). In summary, spruce-based hard carbon has the potential to be an environmentally friendly alternative to standard graphite.