Silicon-Based Solid-State Batteries: Electrochemistry and Mechanics to Guide Design and Operation.

Solid-state batteries (SSBs) are promising alternatives to the incumbent lithium-ion technology; however, they face a unique set of challenges that must be overcome to enable their widespread adoption. These challenges include solid-solid interfaces that are highly resistive, with slow kinetics, and a tendency to form interfacial voids causing diminished cycle life due to fracture and delamination. This modeling study probes the evolution of stresses at the solid electrolyte (SE) solid-solid interfaces, by linking the chemical and mechanical material properties to their electrochemical response, which can be used as a guide to optimize the design and manufacture of silicon (Si) based SSBs. A thin-film solid-state battery consisting of an amorphous Si negative electrode (NE) is studied, which exerts compressive stress on the SE, caused by the lithiation-induced expansion of the Si. By using a 2D chemo-mechanical model, continuum scale simulations are used to probe the effect of applied pressure and C-rate on the stress-strain response of the cell and their impacts on the overall cell capacity. A complex concentration gradient is generated within the Si electrode due to slow diffusion of Li through Si, which leads to localized strains. To reduce the interfacial stress and strain at 100% SOC, operation at moderate C-rates with low applied pressure is desirable. Alternatively, the mechanical properties of the SE could be tailored to optimize cell performance. To reduce Si stress, a SE with a moderate Young's modulus similar to that of lithium phosphorous oxynitride (∼77 GPa) with a low yield strength comparable to sulfides (∼0.67 GPa) should be selected. However, if the reduction in SE stress is of greater concern, then a compliant Young's modulus (∼29 GPa) with a moderate yield strength (1-3 GPa) should be targeted. This study emphasizes the need for SE material selection and the consideration of other cell components in order to optimize the performance of thin film solid-state batteries.

Numerical Design of Microporous Carbon Binder Domains Phase in Composite Cathodes for Lithium-Ion Batteries.

Lithium-ion battery (LIB) performance can be significantly affected by the nature of the complex electrode microstructure. The carbon binder domain (CBD) present in almost all LIB electrodes is used to enhance mechanical stability and facilitate electronic conduction, and understanding the CBD phase microstructure and how it affects the complex coupled transport processes is crucial to LIB performance optimization. In this work, the influence of microporosity in the CBD phase has been studied in detail for the first time, enabling insight into the relationships between the CBD microstructure and the battery performance. To investigate the effect of the CBD pore size distributions, a random field method is used to generate in silico a multiple-phase electrode structure, including bimodal pore size distributions seen in practice and microporous CBD with a tunable pore size and variable transport properties. The distribution of macropores and the microporous CBD phase substantially affected simulated battery performance, where battery specific capacity improved as the microporosity of the CBD phase increased.

Design of Scalable, Next-Generation Thick Electrodes: Opportunities and Challenges.

Lithium-ion battery electrodes are on course to benefit from current research in structure re-engineering to allow for the implementation of thicker electrodes. Increasing the thickness of a battery electrode enables significant improvements in gravimetric energy density while simultaneously reducing manufacturing costs. Both metrics are critical if the transition to sustainable transport systems is to be fully realized commercially. However, significant barriers exist that prevent the use of such microstructures: performance issues, manufacturing challenges, and scalability all remain open areas of research. In this Perspective, we discuss the challenges in adapting current manufacturing processes for thick electrodes and the opportunities that pore engineering presents in order to design thicker and better electrodes while simultaneously considering long-term performance and scalability.

Oncology service initiatives and research in regional Australia.

OBJECTIVE: This paper reflects on the recent growth of cancer research being conducted through some of Australia's rural centres. It encompasses work being done across the fields of clinical, translational and health services research. DESIGN: This is a collaborative piece with contributions from rural health researchers, clinical and cancer services staff from several different regions. CONCLUSION: The past decade has seen an expansion in cancer research in rural and regional Australia driven in part by the recognition that cancer patients in remote areas experience poorer outcomes than their metropolitan counterparts. This work has led to the development of more effective cancer networks and new models of care designed to meet the particular needs of the rural cancer patient. It is hoped that the growth of cancer research in regional centres will, in time, reduce the disparity between rural and urban communities and improve outcomes for cancer patients across both populations.

Adjuvant chemotherapy for early colon cancer: what survival benefits make it worthwhile?

BACKGROUND: We sought to determine the minimum survival benefits that patients judged sufficient to make adjuvant chemotherapy for early colon cancer worthwhile, factors associated with these judgments; and, to compare a self-administered questionnaire with a validated, scripted interview. PATIENTS AND METHODS: One twenty three subjects who completed adjuvant chemotherapy for early colon cancer 3-60 months earlier completed a questionnaire; 97 were randomised to complete an interview before or after the questionnaire. Preferences were elicited by the time trade-off method in 4 hypothetical scenarios. Concordance between the interview and questionnaire was assessed with the intraclass correlation coefficient (ICC). RESULTS: Median age was 65 years (range 19-86), 52% were female and 74% had involved lymph nodes. Over 60% of patients judged an additional 1 month beyond life expectancies of 5 years or 15 years, and an additional 1-2% beyond 5-year survival rates of 85% or 65%, sufficient to make chemotherapy worthwhile. Subjects with tertiary education (p=0.003) or aged 75 years or less (p=0.02) judged larger benefits necessary to make chemotherapy worthwhile. Concordance between the interview and questionnaire was high (ICCs 0.71-0.82). CONCLUSIONS: Most subjects judged small survival benefits sufficient to make adjuvant chemotherapy worthwhile. A self-administered questionnaire was a valid and acceptable way of eliciting preferences.