Search

Two main goals for the industrial, slurry‐based electrode processing are a high process speed and the maximum possible material efficiency. This makes an increased drying rate and active material share favorable, but both are limited by adverse effects on the electrode quality. The adverse effects of fast drying are associated with the migration of binder. In this article, the slurry properties of water‐based graphite slurries are manipulated using a synthetic, layered silicate as additive. The influence of the polymer‐particle composite network on the viscosity, adhesion strength, and cell performance is investigated. By addition of a small amount of additive (0.5 wt% of the dry electrode), the binder migration is mitigated up to a drying rate of 6 g m−2 s−1 for graphite anodes with ≈4.2 mAh cm−2 (corresponding with 30 s drying time) leading to a possible increase of eight times the process speed compared to drying with 0.75 g m−2 s−1 if adverse effects on the tortuosity of the electrodes can be solved. In this work, a combination of additive usage is pointed out with a multilayer approach and first insights are provided in how the binder migration may be mitigated to gain structurally optimized fast‐dried electrodes without losses in electrode quality. [ABSTRACT FROM AUTHOR]

Many methods have been proposed to analyse SEM‐EDS hypermaps of hydrated cementitious materials but none can fit all purposes. In this presentation, we review existing methods for phase identification, stoichiometry quantification, and microstructure quantification in cementitious materials and related materials. We first discuss the unique contribution of SEM‐EDS with respect to the outstanding scientific challenges towards sustainable construction materials. We then compare the SEM‐EDS and image analysis techniques which contribute to answering these challenges. Convergence and divergence in current methods and workflows, and knowledge gaps are highlighted in terms of the specificities of the material (phase assemblage complexity, grain sizes, mixtures, etc.). The discussion is weighted by the required expert knowledge for the sample preparation, microscope operation, and data analysis. We conclude by discussing how microscopy and image analysis integrate into the overall experimental toolkit to investigate and improve cementitious materials. LAY DESCRIPTION: Concretes, mortars and hardened cement pastes are very complex and heterogeneous. As such, the visualisation of phases in the microstructure is often necessary to understand the processes by which this microstructure forms and evolves. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM‐EDS) is one of the techniques that allows studying these materials at the micron‐scale level, by forming images combining the elemental composition. But the analysis of the data is challenging due to the heterogeneity of the material. This article is a review of the latest advancements in the analysis of SEM‐EDS data for cementitious materials. It focuses on two aspects, the most successful applications of SEM‐EDS to study the microstructure of hardened cementitious materials; and some of the main methods used to analyse the dataset. The discussion aims to highlight the requirements of each method and each application, so that readers can pick and mix methods to answer their own scientific questions. [ABSTRACT FROM AUTHOR]

Burning of clinker is the most influencing step of cement quality during the production process. Appropriate characterisation for quality control and decision‐making is therefore the critical point to maintain a stable production but also for the development of alternative cements. Scanning electron microscopy (SEM) in combination with energy dispersive X‐ray spectroscopy (EDX) delivers spatially resolved phase and chemical information for cement clinker. This data can be used to quantify phase fractions and chemical composition of identified phases. The contribution aims to provide an overview of phase fraction quantification by semi‐automatic phase segmentation using high‐resolution backscattered electron (BSE) images and lower‐resolved EDX element maps. Therefore, a tool for image analysis was developed that uses state‐of‐the‐art algorithms for pixel‐wise image segmentation and labelling in combination with a decision tree that allows searching for specific clinker phases. Results show that this tool can be applied to segment sub‐micron scale clinker phases and to get a quantification of all phase fractions. In addition, statistical evaluation of the data is implemented within the tool to reveal whether the imaged area is representative for all clinker phases. [ABSTRACT FROM AUTHOR]

The extended process chain starting from slurry mixing up to the operative lithium‐ion battery requires a deep understanding of each individual process step and knowledge of the interaction of the different process steps with each other. In particular, the intertwining of slurry mixing and drying determines the microstructure of the electrode, which in turn affects the performance of the cell. Herein, a scalable multilayer approach is used to tailor electrodes with improved mechanical and electrochemical properties, which disclose their advantages especially at high drying rates. Cryogenic broad ion beam scanning electron microscopy (Cryo‐BIB‐SEM) micrographs are used to reveal the influences of different process parameters, like slurry formulation, mixing device, and properties of the active material on the intrinsic network between active particles and binders in graphite‐based anode slurries. By a chosen combination of these slurries in a multilayer electrode, a tenfold acceleration of the drying time with favorable mechanical and electrochemical properties for full cells derived from these anodes is demonstrated. [ABSTRACT FROM AUTHOR]