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645 results on '"Lassi, Ulla"'

1. Compton scattering study of strong orbital delocalization in a LiNiO$_2$ cathode

Author

Kothalawala, Veenavee Nipunika, Suzuki, Kosuke, Nokelainen, Johannes, Hyvönen, Arttu, Makkonen, Ilja, Barbiellini, Bernardo, Hafiz, Hasnain, Tynjälä, Pekka, Laine, Petteri, Välikangas, Juho, Hu, Tao, Lassi, Ulla, Takano, Kodai, Tsuji, Naruki, Amada, Yosuke, Devi, Assa Aravindh Sasikala, Alatalo, Matti, Sakurai, Yoshiharu, Sakurai, Hiroshi, and Bansil, Arun

Subjects
Condensed Matter - Materials Science
Abstract

Cobalt is used in Li-ion batteries, but it is expensive and could be replaced by nickel to deliver better performance at a lower cost. With this motivation, we discuss how the character of redox orbitals of LiNiO$_2$ can be ascertained through x-ray Compton scattering measurements combined with parallel first-principles simulations. Our analysis reveals the nature of hole states in Li-doped NiO resulting from the hybridization of O 2$p$ and Ni 3$d$ orbitals. Our study also gives insight into the ferromagnetic ground state and provides a pathway toward the rational design of next-generation battery materials., Comment: 5 pages, 5 figures

Published
2024
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49. Implementing Substrate Treatments to Enhance Adhesion and Facilitate Cyrene as an NMP Alternative for Sustainable Printed Nickel–Manganese–Cobalt‐Based Battery Cathodes.

Author

Roy, Ivy Saha, Taponen, Harri, Välikangas, Juho, Hannila, Esa, Lassi, Ulla, Fabritius, Tapio, and Sliz, Rafal

Abstract

This study proposes a greener approach for electrode preparation using cyrene, a bio‐derived and fully biodegradable green solvent, as a potential N‐methyl‐2‐pyrrolidone substitute for fabricating high‐performance nickel–manganese–cobalt oxide (NMC88) lithium‐ion battery cathodes by screen‐printing method. This study also investigates the replacement of the polyvinylidene fluoride (PVDF) binder with Arkema Kynar HSV1810 homopolymer, a crucial substitution for enabling the effective utilization of cyrene, addressing the solvent inadequacy associated with PVDF dissolution. Alongside the ink formulation, the electrode preparation process is optimized by investigating current collector surface treatments using plasma, ultraviolet, and citric acid to enhance substrate wetting, leading to improved printability, adhesion, and cathode layer performance. Cyrene‐based screen‐printed NMC cathodes are analyzed using various characterization techniques, including microscopy, optical profilometry, scanning electron microscopy, adhesion tests, and electrochemical performance tests for assembled batteries. The results demonstrate that cyrene‐based slurries exhibit improved wettability and adhesion on substrates/current collectors when surface treatments are applied. Furthermore, the electrochemical performance of cells based on surface‐treated NMC88 electrodes prepared with cyrene shows adequate cycling performance and rate capability. As a proof of concept, the study presents an alternative green and sustainable approach for electrode preparation in screen‐printed Li‐ion batteries using cyrene. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Preparation and characterisation of alkali-activated blast furnace slag and Na-jarosite catalysts for catalytic wet peroxide oxidation of bisphenol A.

Author

Hautamäki, Katariina, Heponiemi, Anne, Tuomikoski, Sari, Hu, Tao, and Lassi, Ulla

Subjects
BISPHENOL A, CATALYTIC activity, SLAG, AQUEOUS solutions, SURFACE area, HYDROGEN peroxide
Abstract

In this study, cost-effective alkali-activated materials made from industrial side streams (blast furnace slag and Na-jarosite) were developed for catalytic applications. The catalytic activity of the prepared materials was examined in catalytic wet peroxide oxidation reactions of a bisphenol A in an aqueous solution. All materials prepared revealed porous structure and characterisation expressed the incorporation of iron to the material via ion exchange in the preparation step. Furthermore, the materials prepared exhibited high specific surface areas (over 200 m2/g) and were mainly mesoporous. Moderate bisphenol A removal percentages (35%–37%) were achieved with the prepared materials during 3 h of oxidation at pH 7–8 and 50°C. Moreover, the activity of catalysts remained after four consecutive cycles (between the cycles the catalysts were regenerated) and the specific surface areas decreased only slightly and no changes in the phase structures were observed. Thus, the prepared blast furnace slag and Na-jarosite-based catalysts exhibited high mechanical stability and showed good potential in the removal of bisphenol A from wastewater through catalytic wet peroxide oxidation. [ABSTRACT FROM AUTHOR]

Published
2024
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