This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF) with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a CNF product with low toxicity. Different CNF batches from a pilot plant were characterized with respect to physical properties (chemical composition, specific surface area, morphology, surface chemistry) as well as toxicity by in vitro and in vivo tests. A description of a test battery for both material characterization and toxicity is given. The results illustrate how the adjustment of production parameters and purification, thermal treatment in particular, influence the material characterization as well as the outcome of the toxic tests. The combination of the tests early during product development is a useful and efficient approach when aiming at designing CNF with low toxicity. Early quality and safety characterization, preferably in an iterative process, is expected to be efficient and promising for this purpose. The toxicity tests applied are preliminary tests of low cost and rapid execution. For further studies, effects such as lung inflammation, fibrosis and respiratory cancer are recommended for the more in-depth studies of the mature CNF product.

Due to global warming, technologies reducing CO2 emissions in the metallurgical industry are being sought. One possibility is to use bio-coke as a substitute for classic coke made of 100% fossil coal. Bio-coke can be produced on the basis of coal with the addition of substances of biomass origin. Blends for the production of bio-coke should have appropriate coke-making properties to ensure the appropriate quality of bio-coke. The article presents the results of the research on the influence of the addition (up to 20%) of bio-components of different origins to the coke blend on its coke-making properties, i.e., Gieseler Fluidity, Arnu—Audibert Dilatation and Roga Index. The bio-components used in the research were raw and thermally processed waste biomass of different origins (forestry: beech and alder woodchips; sawmill: pine sawdust; and the food industry: hazelnut shells and olive kernels) and commercial charcoal. Studies have shown that both the amount of additive and the type of additive affect the obtained coking properties. There was a decrease in fluidity, dilatation and Roga Index values, with more favorable results obtained for the addition of carbonized biomass and for additives with a higher apparent density. A regressive mathematical model on the influence of the share of the additive and its properties (oxygen content and apparent density) on the percentage decrease in fluidity was also developed.

Over the next half decade, significant changes expected in global carbon structures, carbon products and applications. Technological advances that improve the structure-property relationship of advanced carbon materials and breakthrough in manufacturing processes resulting in lower cost, leads to availability of carbon nano materials for applications in the metallurgical industry with a reference to electrodes for the metallurgical industry.In the current work we synthesized pitch-based C/C nano composite lab scale electrodes, partially replacing petroleum coke with nanofibers, by using a ball milling dispersion and high energy milling technique. The effect of different processing variables including the amount of binder and dispersants as well as mixing conditions is investigated. Low vacuum -SEM analyses of green pitch and dispersant samples show the pitch coating on dispersants. Field emission gun (FEG)-SEM is used to analyse dispersants, baked pitch/dispersant system as well baked electrodes. Transmission electron microscope (TEM) is applied to investigate in detail the primary structure of the dispersants, as well as the fiber/matrix interface and the alignment of binder with the fibres in graphitized and un-graphitized electrodes.

Elkem is one of the world’s leading companies for environment-friendly production of metals and materials. Among its principal products are metallurgical silicon, solar grade silicon, and different forms of carbon. For the coming generation of Li-ion batteries, silicon is a very attractive candidate to replace graphite as anodic material due to its remarkable energy density (3.6 Ah/g) and volumetric capacity (8.3 Ah/ccm). To tackle the massive cracking and degradation typically observed during electrochemical cycling of silicon anodes, we are developing composite nanostructured materials based on existing production of silicon and carbon at Elkem. The goal is to use silicon of optimum purity and doping w.r.t. production costs and performance mixed with carbon materials through milling techniques in a commercially viable way resulting in a product that can be used as anode material in Li-ion batteries. Results show that performance can be substantially improved by using appropriate milling methods. The current presentation focuses on silicon-carbon nanostructures obtained by high-energy ball-milling in argon atmosphere. Silicon-carbon composites showed improved cycle life-time with ball-milling time, though usually accompanied with a loss of initial capacity due to high-surface area and extensive SEI formation. More pronounced improvements were achieved by co-milling silicon with graphite. Further enhancements were obtained by using additives in the electrolyte and by controlling the delithiation step during cycling. The electrochemical performance was tested in half cells where typically the working electrode was made by mixing a silicon-carbon composite powder with an organic binder in an aqueous slurry and coated on a Cu-foil. Lithium metal was used as the counter electrode. Structural properties and degradation mechanisms were examined by electron microscopy (SEM, FIB-SEM, TEM) and XRD. Figure txt: A) Charge (delithiation) capacity retention for selected Si-C based materials. The electrodes were cycled with C/20 rate for the three first and the last cycle. Other cycles were performed at C/10 rate (C-rate was based on the mass of Si assuming full capacity of 3.6 Ah/gSi). The curves labeled 1 was for materials only treated by low-energy milling of Si. A rapid decrease in capacity is seen already from cycle one. This is in contrast to composite materials made by mixed milling of graphite and silicon by high-energy ball milling (curves labeled 2 represents material milled for 20 minutes at 800 rpm, curves labeled 3 were milled at 5 minutes) where a rapid degradation zone appears first after ca. 10 cycles. FIB-SEM cross-sectional images of the cycled electrodes (cycle 8 – just before rapid degradation sets in, cycle 15 – middle of rapid degradation zone, and “dead” electrode after 55 cycles) show that the electrodes gradually become clogged both by SEI formation and Si-intergrowth and lose porosity. This is accompanied with a thickness increase, most dramatically seen after the rapid degradation zone. B) Discharge-charge characteristics for a composite Si+C electrode restricting the charge capacity to 1200 mAh/gSi pr. cycle (material: 80wt.% Si and 20wt.% graphite ball-milled for 5 minutes at 800 rpm). All electrodes were tested as half-cells with a Li-counter electrode and consisted of 60wt.% silicon, 30wt.% graphite, 2 wt.% carbon black and 8wt.% CMC. Typical loading of the active material was 0.8-1.0 mg/cm2.