Origins of Irreversibility in Layered NaNixFeyMnzO2 Cathode Materials for Sodium Ion Batteries.

Layered NaNixFeyMnzO2 cathode (NFM) is of great interest in sodium ion batteries because of its high theoretical capacity and utilization of abundant, low-cost, environmentally friendly raw materials. Nevertheless, there remains insufficient understanding on the concurrent local environment evolution in each transition metal (TM) that largely influences the reversibility of the cathode materials upon cycling. In this work, we investigate the reversibility of TM ions in layered NFMs with varying Fe contents and potential windows. Utilizing ex situ synchrotron X-ray absorption near-edge spectroscopy and extended X-ray absorption fine structure of precycled samples, the valence and bonding evolution of the TMs are elucidated. It is found that Mn is electrochemically inactive, as indicated by the insignificant change of Mn valence and the Mn-O bonding distance. Fe is electrochemically inactive after the first five cycles. The Ni redox couple contributes most of the charge compensation for NFMs. Ni redox is quite reversible in the cathodes with less Fe content. However, the Ni redox couple shows significant irreversibility with a high Fe content of 0.8. The electrochemical reversibility of the NFM cathode becomes increasingly enhanced with the decrease of either Fe content or with lower upper charge cutoff potential.

Ultrasound-Assisted Removal of A Fishbone Stuck in A Tongue in the Emergency Department.

BACKGROUND: Foreign body (FB) impaction in the oropharyngeal region-and specifically the tongue-is a common problem in the emergency department that often requires specialty consultation and admission for operative intervention. Over the years, the use of point of care ultrasound (POCUS) has increased ease and success of FB removal in other anatomic regions, but is only rarely reported for extraction of FB from the tongue outside of the operating room. CASE REPORT: This case demonstrates a unique case of ultrasound-guided removal of a fishbone from the tongue in the emergency department after blind attempts failed. Operative intervention and admission were initially avoided; however, because of initial failed attempts and blind dissection before the use of POCUS, the patient presented a day later requiring admission for postprocedural tongue swelling and edema. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should be aware that POCUS may assist in FB localization in the tongue.