Representations of *-regular rings and their ortholattices of projections

We show that a subdirectly irreducible *-regular ring admits a representation within some inner product space provided so does its ortholattice of projections

Modeling Aqueous Zinc-Ion Batteries: The Influence of Electrolyte Speciation on Cell Performance

Zinc-based batteries are among the longest-used cell systems, yet they show increasing research interest in the last years [1]. The high specific capacity of zinc metal anodes combined with their stability in aqueous electrolytes and abundance highlights their potential in a growing market for energy storage systems. The long-commercialized alkaline cell chemistry, a zinc metal anode and a manganese dioxide cathode, showed increased rechargeability when switching to mildly acidic electrolytes [2]. While the charge transport of zinc-ions is widely acknowledged and distinguishes them from alkaline electrolytes, in-detail charge storage mechanisms are under debate [3]. The electrolyte's role in this process and its influence on cell performance and stability is often overlooked. We employ a thermodynamically consistent dynamic cell model to describe aqueous zinc-ion batteries' behavior in our work. The model includes a thermodynamical equilibrium description of complex formations. Species composition significantly alters the transport properties and stability of both the electrolyte and the cathode. We predict cell behavior and cycling performance for different electrolytes and electrode materials. Putting this into the context of cell parametrization and rate limitations, we describe possible pitfalls and identify goals for the ongoing optimization of zinc-ion batteries

A Multi-Process Cathode Model for MnO2-based Aqueous Zinc-Ion Batteries

Rapidly rising electricity prices on the European energy market flared up an accompanying discus-sion about the revival of nuclear power and gas-fired power plants as bridging technologies. This situation emphasises the urgency of powerful and affordable electrochemical energy storage systems for a rapid energy transition. Next-generation storage technologies are in a tight race competing in energy density, environmental safety and cost per capacity. Zinc-based anodes are commercial highly success-ful for several decades, yet there is no commercialised zinc-insertion cathode yet. Manganese dioxide cathodes, which are widely used in alkaline cells, were shown to have a reversible zinc storage capacity in mild electrolytes. This increased the research interest in zinc-ion batteries in the last decade, and many successful systems were proposed. Aqueous metal batteries face a series of challenges. The dynamic electrolyte composition and pH profile heavily influence performance, and many side reactions occur. This contribution presents a thermodynamically consistent dynamic cell model, which considers the electrolyte's complex formation and related transport properties. Additionally, it implements a multi-process model for the MnO2 cathode, reflecting the most reported side reactions in literature, manganese dissolution, and proton co-insertion. We use this to identify well-known experimental characteristics, describe possible pitfalls, and identify goals for further optimising zinc-ion batteries

Model-Based Electrolyte Design for Rechargeable Zinc Ion Batteries

Materials for next-generation batteries are optimized and characterized in terms of energy- and power density. Nevertheless, the growing market for stationary energy storage needs affordable and safe cell chemistries. Zinc-metal electrodes are highly successful in primary alkaline and zinc-air batteries due to their high specific energy and the abundance of zinc and have a remarkably high voltage in aqueous electrolytes. As used in commercialized zinc systems, traditional alkaline electrolytes show a Zn/ZnO conversion reaction at the anode. While Zn2+ transport in the electrolyte and its insertion process is broadly adressed [1], neither its specific interaction with different electrolytes nor the influence of the electrolyte on cathodic and anodic reactions is well studied. Furthermore, the limited electrochemical stability window of aqueous electrolytes leads to hydrogen evolution at the anode and H+ insertion at the cathode. All in all, the electrolyte is not an inert, idealistic charge carrier but significantly contributes to cell behaviour and performance. Within zinc-air batteries, we have performed model-based optimization studies of pH adjusted electrolytes [2,3]. To get a deeper understanding of this interplay in zinc-ion batteries, we have developed a model based on equilibrium thermodynamics of the electrolytes speciation interacting with a dynamic cell model. Consistent with simulations for primary alkaline cells, our model for a Zn/MnO2 cell chemistry includes H+ insertion into the cathode, forming MnOOH. Switching to near-neutral electrolytes, the electrolyte speciation and zinc solubility also allow a zinc transport and insertion mechanism [4], which we investigate and study not only for ZnSO4 but also for newly proposed electrolytes such as Zn(OTf)2. In our contribution, we discuss the origin for varying cell performance in the most common electrolytes, compare the electrode capacities by different charge storage processes and investigate the likelihood of hydrogen evolution based on electrolyte choice and rate behaviour.

Modelling Aqueous Zinc-Ion Batteries with a Novel Multi-Process Description of MnO2-based Cathodes

Amid the energy transition, the highly fluctuating supply from renewable energies prevents a rapid shift away from fossil fuels. It increases energy prices, further fuelled by geopolitical instabilities in gas supply. This situation emphasises the urgency of powerful and affordable electrochemical energy storage systems for a successful energy transition. Next-generation storage technologies are in a tight race competing in energy density, environmental safety, and cost per capacity. For several decades, zinc-based anodes have been commercially successful, though no production-ready zinc-insertion cathode exists yet. Manganese dioxide cathodes, widely used in alkaline cells, present a reversible zinc storage capacity in mild aqueous electrolytes. This finding increased the research interest in zinc-ion batteries in the last decade, and many successful systems were proposed. A series of challenges are facing aqueous metal batteries. The limited electrochemical stability of the electrolyte, the dynamic electrolyte composition and sensitivity to variations in local pH heavily influence performance. Additionally, a single redox couple rarely describes the cells cycling behaviour. This contribution presents a thermodynamically consistent dynamic cell model, which considers the electrolyte's complex formation and coupled transport properties. Building on this, we implement a multi-process model for the manganese oxide cathode, reflecting the most reported side reactions in literature, manganese dissolution, and proton co-insertion. We use this to identify experimental characteristics, describe pinholes, and identify optimisation potential for next-generation zinc batteries

Modeling Aqueous Zinc-Ion Batteries: The Influence of Electrolyte Speciation on Cell Performance

Zinc-based batteries are among the longest-used cell systems, yet they show increasing research interest in the last years [1]. The high specific capacity of zinc metal anodes combined with their stability in aqueous electrolytes and abundance highlights their potential in a growing market for energy storage systems. The long-commercialized alkaline cell chemistry, a zinc metal anode and a manganese dioxide cathode, showed increased rechargeability when switching to mildly acidic electrolytes [2]. While the charge transport of Zn2+ is widely acknowledged and distinguishes them from alkaline electrolytes, in-detail charge storage mechanisms are under debate [3]. The electrolyte's role in this process and its influence on cell performance and stability is often overlooked. We employ a thermodynamically consistent dynamic cell model to describe aqueous zinc-ion batteries' behavior in our work. The model includes a thermodynamical equilibrium description of complex formations. Species composition significantly alters the transport properties and stability of both the electrolyte and the cathode. We predict cell behavior and cycling performance for different electrolytes and electrode materials. Putting this into the context of cell parametrization and rate limitations, we describe possible pitfalls and identify goals for the ongoing optimization of zinc-ion batteries

Chemical Conversion of Fischer-Tropsch Waxes and Plastic Waste Pyrolysis Condensate to Lubricating Oil and Potential Steam Cracker Feedstock

The global economy and its production chains must move away from petroleum-based products, to achieve this goal, alternative carbon feedstocks need to be established. One area of concern is sustainable production of synthetic lubricants. A lubricating oil can be described as a high boiling point (>340 ◦C) liquid with solidification at least below room temperature. Historically, many lubricants have been produced from petroleum waxes via solvent or catalytic dewaxing. In this study, catalytic dewaxing was applied to potential climate neutral feedstocks. One lubricant was produced via Fischer–Tropsch (FT) synthesis and the other lubricant resulted from low temperature pyrolysis of agricultural waste plastics. The waxes were chosen because they each represented a sustainable alternative towards petroleum, i.e., FT waxes are contrivable from biomass and CO2 by means of gasification and Power-to-X technology. The pyrolysis of plastic is a promising process to complement existing recycling processes and to reduce environmental pollution. Changes in cloud point, viscosity, and yield were investigated. A bifunctional zeolite catalyst (SAPO-11) loaded with 0.3 wt% platinum was used. The plastic waste lubricants showed lower cloud points and increased temperature stability as compared with lubricants from FT waxes. There was a special focus on the composition of the naphtha, which accumulated during cracking. While the plastic waste produced higher amounts of naphtha, its composition was quite similar to those from FT waxes, with the notable exception of a higher naphthene content

The Cycling Mechanism of Manganese-Oxide Cathodes in Zinc Batteries: A Theory-Based Approach

Zinc-based batteries offer good volumetric energy densities and are compatible with environmentally friendly aqueous electrolytes. Zinc-ion batteries (ZIBs) rely on a lithium-ion-like Zn2+-shuttle, which enables higher roundtrip efficiencies and better cycle life than zinc-air batteries. Manganese-oxide cathodes in near-neutral zinc sulfate electrolytes are the most prominent candidates for ZIBs. Zn2+-insertion, H+-insertion, and Mn2+-dissolution are proposed to contribute to the charge-storage mechanism. During discharge and charge, two distinct phases are observed. Notably, the pH-driven precipitation of zinc-sulfate-hydroxide is detected during the second discharge phase. However, a complete and consistent understanding of the two-phase mechanism of these ZIBs is still missing. This paper presents a continuum full cell model supported by density functional theory (DFT) calculations to investigate the implications of these observations. The complex-formation reactions of near-neutral aqueous electrolytes are integrated into the battery model and, in combination with the DFT calculations, draw a consistent picture of the cycling mechanism. The interplay between electrolyte pH and reaction mechanisms is investigated at the manganese-oxide cathodes and the dominant charge-storage mechanism is identified. The model is validated with electrochemical cycling data, cyclic voltammograms, and in situ pH measurements. This allows to analyze the influence of cell design and electrolyte composition on cycling and optimize the battery performance