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Aqueous ammonium‐ion batteries (AAIBs) are considered as one of the most promising technologies for large scale energy storage applications, due to their intrinsic safety, environmental friendliness and low cost. Nevertheless, the practical application of AAIBs is impeded by hydrogen evolution reaction (HER) occurring in diluted aqueous electrolyte. Highly concentrated electrolytes can improve electrochemical stability but lead to higher costs and increased hydrolysis of NH4+. In this work ethylene glycol (EG) is proposed as co‐solvent, which can act as H‐bond modulating agent, to increase the stability of AAIBs with diluted electrolytes. The perturbation of water H‐bond network regulated by EG is proved by spectroscopic methods, while the suppressed HER is confirmed by differential electrochemical mass spectrometry (DEMS) results. As a result, full cells with 3,4,9,10‐perylenebis(dicarboximide) (PTCDI) anode and FeFe(CN)6 (FeHCF) cathode and EG‐added electrolyte exhibit stable cycling performance with capacity retention of 77% after 1950 cycles. [ABSTRACT FROM AUTHOR]

Aqueous zinc–air batteries (ZABs) are a low‐cost, safe, and sustainable technology for stationary energy storage. ZABs with pH‐buffered near‐neutral electrolytes have the potential for longer lifetime compared to traditional alkaline ZABs due to the slower absorption of carbonates at nonalkaline pH values. However, existing near‐neutral electrolytes often contain halide salts, which are corrosive and threaten the precipitation of ZnO as the dominant discharge product. This paper presents a method for designing halide‐free aqueous ZAB electrolytes using thermodynamic descriptors to computationally screen components. The dynamic performance of a ZAB with one possible halide‐free aqueous electrolyte based on organic salts is simulated using an advanced method of continuum modeling, and the results are validated by experiments. X‐ray diffraction, scanning electron microscopy, and energy dispersive X‐ray spectroscopy measurements of Zn electrodes show that ZnO is the dominant discharge product, and operando pH measurements confirm the stability of the electrolyte pH during cell cycling. Long‐term full cell cycling tests are performed, and rotating ring disk electrode measurements elucidate the mechanism of oxygen reduction reaction and oxygen evolution reaction. The analysis shows that aqueous electrolytes containing organic salts could be a promising field of research for zinc‐based batteries, due to their Zn2+ chelating and pH buffering properties. The remaining challenges including the electrochemical stability of the electrolyte components are discussed. [ABSTRACT FROM AUTHOR]

To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2+ and CO2+ ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2, whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed. [ABSTRACT FROM AUTHOR]

Cobalt-free LiNi 0.5 Mn 1.5 O 4 (LNMO) is a promising alternative to the commonly used cobalt-containing positive electrode active materials in lithium-ion batteries (LIBs), owing to its high redox potential, relatively low cost, and low environmental impact. The high cell voltage, however, comes along with several challenges that need to be overcome before the material can be successfully used in commercial cells. Herein, these challenges are addressed by introducing three additives into the liquid organic carbonate-based electrolyte, namely tris(trimethylsilyl)-phosphite (TTSPi), lithium bis(oxalato) borate (LiBOB), and ethyl-(2,2,2-trifluoroethyl) carbonate (TFEC). The optimized electrolyte composition enables superior performance of Li‖LNMO and graphite‖LNMO cells because of the stabilized interphases at both the negative and the positive electrode and, thus, suppressed electrolyte decomposition. This is demonstrated by the substantially reduced gassing upon cycling and shelf-storage. These results are anticipated to contribute to the successful commercialization of LNMO in more sustainable LIBs. [Display omitted] • Stabilized interphases at the positive and negative electrode. • Mitigated transition metal cross-talk. • Reduced gas evolution upon cycling and storage. • Fully aqueous processed graphite‖LiNi 0.5 Mn 1.5 O 4 lithium-ion cells. [ABSTRACT FROM AUTHOR]