Low-cost and high-performance lithium ion batteries (LIBs) are a key technology in these days. One promising candidate for cathodes is the layered nickel (Ni)-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) active material due to its high energy density, high specific capacity and lower material costs as well as social aspects concerning mining due to the diminished cobalt content. However, the lower thermal stability and higher sensitivity to H2O and CO2 result in a potential stronger performance degradation and lower safety. Therefore, process adaptions are inevitable. In this paper the current status and challenges of the entire cathode production process with NCM811 as active material are reviewed taking quality, cost and environmental aspects into account. General important aspects within the process are presented which are specially extended to NCM811 cathode production. Process recommendations are highlighted and innovative approaches like a water-based or solvent-free processing are discussed in comparison to conventional production technologies.
Solid-state batteries possess the potential to combine increased energy densities, high voltages, as well as safe operation and therefore are considered the future technology for electrical energy storage. In particular, sulfides as solid electrolyte are promising candidates due to their high ionic conductivities and the possibility of a scalable production. This review aims to demonstrate ways to manufacture suspension-based sulfidic solid-state batteries both on a laboratory scale and on an industrial level, focusing on the assessment of current knowl-edge and its discussion from a process engineering point of view. In addition to the influence of process parameters during mechanochemical synthesis of the solid electrolyte, formulation strategies for electrodes and separators are presented. The process chain from dispersion to cell assembly is evaluated. Scale-up technologies are considered in comparison to established techniques in the field of conventional lithium-ion batteries with liquid electrolyte summarizing the current status of sulfidic solid-state battery production.
For batteries with high energy density and good fast-charge capability, NCM cathode active materials with ≥80 mol% nickel are promising due to their high specific capacities. Unfortunately, the increase in nickel content is accompanied by a high susceptibility to moisture. Therefore, nickel-rich NCM is coated or doped by the manufacturers to increase its stability. However, it is unclear if special requirements regarding ambient humidity must still be met during the whole production chain, or only after post-drying and during cell assembly. Therefore, the structure and properties of three different nickel-rich NCM active materials (one doped monocrystalline, two coated polycrystalline materials) processed at ambient atmosphere were investigated. At every process step, moisture content and microstructure were examined. Prior to cell assembly, two different post-drying procedures were applied and investigated. As validation, electrochemical tests were performed. Both polycrystalline cathodes demonstrated good physical and electrochemical properties, despite the ambient process atmosphere. Higher moisture reduction led to improved electrochemical performances at higher C-rates. Finally, a comparison between dry and normal atmosphere of the best performing material indicates that a production of high-quality nickel-rich electrodes at ambient atmosphere is possible if their exposure to moisture is short and well-designed post-drying techniques are applied.
Lignin is the most abundant aromatic polymer in nature and a promising renewable source for the provision of aromatic platform chemicals and biofuels. β-Etherases are enzymes with a promising potential for application in lignin depolymerization due to their selectivity in the cleavage of β-O-4 aryl ether bonds. However, only a very limited number of these enzymes have been described and characterized so far. Using peptide pattern recognition (PPR) as well as phylogenetic analyses, 96 putatively novel β-etherases have been identified, some even originating from bacteria outside the order Sphingomonadales. A set of 13 diverse enzymes was selected for biochemical characterization, and β-etherase activity was confirmed for all of them. Some enzymes displayed up to 3-fold higher activity than previously known β-etherases. Moreover, conserved sequence motifs specific for either LigE- or LigF-type enzymes were deduced from multiple-sequence alignments and the PPR-derived peptides. In combination with structural information available for the β-etherases LigE and LigF, insight into the potential structural and/or functional role of conserved residues within these sequence motifs is provided. Phylogenetic analyses further suggest the presence of additional bacterial enzymes with potential β-etherase activity outside the classical LigE- and LigF-type enzymes as well as the recently described heterodimeric β-etherases. IMPORTANCE The use of biomass as a renewable source and replacement for crude oil for the provision of chemicals and fuels is of major importance for current and future societies. Lignin, the most abundant aromatic polymer in nature, holds promise as a renewable starting material for the generation of required aromatic structures. However, a controlled and selective lignin depolymerization to yield desired aromatic structures is a very challenging task. In this regard, bacterial β-etherases are especially interesting, as they are able to cleave the most abundant bond type in lignin with high selectivity. With this study, we significantly expanded the toolbox of available β-etherases for application in lignin depolymerization and discovered more active as well as diverse enzymes than previously known. Moreover, the identification of further β-etherases by sequence database mining in the future will be facilitated considerably through our deduced etherase-specific sequence motifs.
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