Using Hierarchically Structured, Nanoporous Particles as Building Blocks for NCM111 Cathodes

Nanoparticles have many advantages as active materials, such as a short diffusion length, low charge transfer resistance, or a reduced probability of cracking. However, their low packing density makes them unsuitable for commercial battery applications. Hierarchically structured microparticles are synthesized from nanoscale primary particles by targeted aggregation. Due to their open accessible porosity, they retain the advantages of nanomaterials but can be packed much more densely. However, the intrinsic porosity of the secondary particles leads to limitations in processing properties and increases the overall porosity of the electrode, which must be balanced against the improved rate stability and increased lifetime. This is demonstrated for an established cathode material for lithium-ion batteries (LiNi0.33Co0.33Mn0.33O2, NCM111). For active materials with low electrical or ionic conductivity, especially post-lithium systems, hierarchically structured particles are often the only way to produce competitive electrodes.

Micron-Sized Pored Membranes Based on Polyvinylidene Difluoride Hexafluoropropylene Prepared by Phase Inversion Techniques

In this study, micron-sized pored membranes, based on the co-polymer polyvinylidene difluoride hexafluoropropylene (PVdF-HFP) were prepared via phase inversion techniques. The aim of the approach was to find less harmful and less toxic solvents to fabricate such films. Therefore, the Hansen solubility approach was used to identify safer and less toxic organic solvents for the phase inversion process, relative to present solvent mixtures, based on acetone, dimethyl formamide, dimethyl acetamide or methanol. With this approach, it was possible to identify cyclopentanone, ethylene glycol and benzyl alcohol as suitable solvents for the membrane preparation process. Physicochemical and mechanical properties were analyzed and compared, which revealed a uniform membrane structure through the cross section. Differences were observed at the top surface, in dependence of both preparation approaches, which are described in detail.

Perceived Usefulness and Satisfaction of Mobile Phone for Users with Disabilities

The United Nations Convention on the Rights of Persons with Disabilities came into force in 2008. The ICT Opportunity for a Disability-Inclusive Development Framework produced by UNESCO in 2013 formulated a development agenda for these rights, highlighting the importance of mobile devices in this development effort. For most persons with disabilities, the mobile phone is an innovation. What factors affect their satisfaction of mobile phones? The technology acceptance model (TAM) suggests that the perceived usefulness of the device will affect a person’s attitude towards the technology and the associated satisfaction. This study examines the perceived usefulness of mobile phones for persons with disabilities. A survey was conducted. The structural equation model developed showed the latent variable Perceived Usefulness, manifested as Social Function, Emergency Help, Sense of Security, positively affected user satisfaction. Implications for enhancing mobile phone perceived usefulness for users with disabilities are discussed.