A Review of Lithium-Ion Battery Electrode Drying: Mechanisms and Metrology

Lithium-ion battery manufacturing chain is extremely complex with many controllable parameters especially for the drying process. These processes affect the porous structure and properties of these electrode films and influence the final cell performance properties. However, there is limited available drying information and the dynamics are poorly understood due to the limitation of the existing metrology. There is an emerging need to develop new methodologies to understand the drying dynamics to achieve improved quality control of the electrode coatings. A comprehensive summary of the parameters and variables relevant to the wet electrode film drying process is presented, and its consequences/effects on the finished electrode/final cell properties are mapped. The development of the drying mechanism is critically discussed according to existing modeling studies. Then, the existing and potential metrology techniques, either in situ or ex situ in the drying process are reviewed. This work is intended to develop new perspectives on the application of advanced techniques to enable a more predictive approach to identify optimum lithium-ion battery manufacturing conditions, with a focus upon the critical drying process

Towards optimised cell design of thin film silicon-based solid-state batteries via modelling and experimental characterisation

To realise the promise of solid-state batteries, negative electrode materials exhibiting large volumetric expansions, such as Li and Si, must be used. These volume changes can cause significant mechanical stresses and strains that affect cell performance and durability, however their role and nature in SSBs are poorly understood. Here, a 2D electro-chemo-mechanical model is constructed and experimentally validated using steady-state, transient and pulsed electrochemical methods. The model geometry is taken as a representative cross-section of a non-porous, thin-film solid-state battery with an amorphous Si (a-Si) negative electrode, lithium phosphorous oxynitride (LiPON) solid electrolyte and LiCoO2 (LCO) positive electrode. A viscoplastic model is used to predict the build-up of strains and plastic deformation of a-Si as a result of (de)lithiation during cycling. A suite of electrochemical tests, including electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique and hybrid pulse power characterisation are carried out to establish key parameters for model validation. The validated model is used to explore the peak interfacial (a-Si∣LiPON) stress and strain as a function of the relative electrode thickness (up to a factor of 4), revealing a peak volumetric expansion from 69% to 104% during cycling at 1C. The validation of this electro-chemo-mechanical model under load and pulsed operating conditions will aid in the cell design and optimisation of solid-state battery technologies

Socioeconomic inequalities in health among Swedish adolescents - adding the subjective perspective

Abstract Background Socioeconomic inequalities in adolescent health predict future inequalities in adult health. Subjective measures of socioeconomic status (SES) may contribute with an increased understanding of these inequalities. The aim of this study was to investigate socioeconomic health inequalities using both a subjective and an objective measure of SES among Swedish adolescents. Method Cross-sectional HBSC-data from 2002 to 2014 was used with a total sample of 23,088 adolescents aged 11–15 years. Three measures of self-rated health (dependent variables) were assessed: multiple health complaints, life satisfaction and health perception. SES was measured objectively by the Family Affluence Scale (FAS) and subjectively by “perceived family wealth” (independent variables). The trend for health inequalities was investigated descriptively with independent t-tests and the relationship between independent and dependent variables was investigated with multiple logistic regression analysis. Gender, age and survey year was considered as possible confounders. Results Subjective SES was more strongly related to health outcomes than the objective measure (FAS). Also, the relation between FAS and health was weakened and even reversed (for multiple health complaints) when subjective SES was tested simultaneously in regression models (FAS OR: 1.03, CI: 1.00;1.06 and subjective SES OR: 0.66, CI: 0.63;0.68). Conclusions The level of socioeconomic inequalities in adolescent health varied depending on which measure that was used to define SES. When focusing on adolescents, the subjective appraisals of SES is important to consider because they seem to provide a stronger tool for identifying inequalities in health for this group. This finding is important for policy makers to consider given the persistence of health inequalities in Sweden and other high-income countries

Lighting and recognition of emotion conveyed by facial expressions

A recent study examined how luminance and spectral power distribution affect recognition of facial expression, a proxy for pedestrians' judgements concerning the apparent intent of other people. This paper describes a repeat study which included a greater number of test luminances, a third type of lamp, and an additional, shorter duration of observation (500 ms). Luminance and distance had significant effects on expression recognition; the effect of lamp was not significant and the effect of duration was suggested to be significant only within the escarpment region of the performance versus luminance relationship. The results were used to estimate appropriate light levels for outdoor lighting. A luminance of 1.0 cd/m2 permits facial expressions to be identified with a 50% probability of correct identification at a distance of 15 m

The effect of fog on detection of driving hazards after dark

The presence of fog leads to an increase in road traffic accidents. An experiment was carried out using a scale model to investigate how the detection of hazards in peripheral vision was affected by changes in luminance (0.1 cd/m2 and 1.0 cd/m2 road surface luminance), scotopic/photopic (S/P) ratio (0.65 and 1.40) and fog density (none, thin and thick). Two hazards were used, a road surface obstacle and lane change of another vehicle. Increasing luminance, and reducing from thick to thin fog, led to significant increase in detection rate and a reduction in reaction time, for both types of hazard. The effect of a change in S/P ratio was significant only when measuring detection of the surface obstacle using reaction times, under the thick fog, with an increase in S/P ratio leading to a shorter reaction time

Lighting for cycling in the UK : a review

While UK governments have recently sought to increase cycling activity, it remains a minority interest. One reason for this is the perceived danger of cycling on roads filled with traffic. There is statistical evidence to support this perception; for equal exposure, cyclists are more likely to be seriously injured than either drivers or pedestrians. Lighting has a role to play in reducing the hazards of cycling by enhancing the visibility and conspicuity of cyclists. Unfortunately, it is not at all clear that the current lighting regulations and recommendations for cycling and cyclists are the best that can be achieved or are even adequate for these purposes. A number of actions are suggested that should enable lighting’s contribution to the safety of cyclists to be realized

Global Diversity Hotspots and Conservation Priorities for Sharks

Sharks are one of the most threatened groups of marine animals, as high exploitation rates coupled with low resilience to fishing pressure have resulted in population declines worldwide. Designing conservation strategies for this group depends on basic knowledge of the geographic distribution and diversity of known species. So far, this information has been fragmented and incomplete. Here, we have synthesized the first global shark diversity pattern from a new database of published sources, including all 507 species described at present, and have identified hotspots of shark species richness, functional diversity and endemicity from these data. We have evaluated the congruence of these diversity measures and demonstrate their potential use in setting priority areas for shark conservation. Our results show that shark diversity across all species peaks on the continental shelves and at mid-latitudes (30–40 degrees N and S). Global hotspots of species richness, functional diversity and endemicity were found off Japan, Taiwan, the East and West coasts of Australia, Southeast Africa, Southeast Brazil and Southeast USA. Moreover, some areas with low to moderate species richness such as Southern Australia, Angola, North Chile and Western Continental Europe stood out as places of high functional diversity. Finally, species affected by shark finning showed different patterns of diversity, with peaks closer to the Equator and a more oceanic distribution overall. Our results show that the global pattern of shark diversity is uniquely different from land, and other well-studied marine taxa, and may provide guidance for spatial approaches to shark conservation. However, similar to terrestrial ecosystems, protected areas based on hotspots of diversity and endemism alone would provide insufficient means for safeguarding the diverse functional roles that sharks play in marine ecosystems