Identifying Defects in Li-Ion Cells Using Ultrasound Acoustic Measurements

Identification of the state-of-health (SoH) of Li-ion cells is a vital tool to protect operating battery packs against accelerated degradation and failure. This is becoming increasingly important as the energy and power densities demanded by batteries and the economic costs of packs increase. Here, ultrasonic time-of-flight analysis is performed to demonstrate the technique as a tool for the identification of a range of defects and SoH in Li-ion cells. Analysis of large, purpose-built defects across multiple length scales is performed in pouch cells. The technique is then demonstrated to detect a microscale defect in a commercial cell, which is validated by examining the acoustic transmission signal through the cell. The location and scale of the defects are confirmed using X-ray computed tomography, which also provides information pertaining to the layered structure of the cells. The demonstration of this technique as a methodology for obtaining direct, non-destructive, depth-resolved measurements of the condition of electrode layers highlights the potential application of acoustic methods in real-time diagnostics for SoH monitoring and manufacturing processes

Reflections on personal psychological resilience arising from the Shoreham air crash in 2015

Following critical events many people experience a period of emotional and cognitive disturbance before re-establishing well-being without the need for formal psychological support. Those working in emergency care have frequent and repeated exposure to such incidents and are therefore at increased risk of psychological distress. This article discusses the psychological sequalae of the author’s witnessing and involvement in the immediate on-scene care of those injured in the Shoreham, England air show crash in August 2015. Using narrative reflection, the author describes, with reference to the literature, his psychological journey drawing particularly on the conservation of resources theory. Within this is the recognition that unduly early and misinformed emphasis on psychological disorder and post-traumatic stress disorder are not only unhelpful but may deliver the person into greater distress and long-term mental health problems