A simple solution‐phase technique is used to synthesize crystalline lithium niobate nanostructures roughly 7 nm in diameter and up to 100 nm in length. The observed anisotropy is the result of directed aggregation between the exposed 001 facets of the nanoparticles produced.

ChatGPT, a language-learning model chatbot, has garnered considerable attention for its ability to respond to users’ questions. Using data from 14 countries and 186 institutions, we compare ChatGPT and student performance for 28,085 questions from accounting assessments and textbook test banks. As of January 2023, ChatGPT provides correct answers for 56.5 percent of questions and partially correct answers for an additional 9.4 percent of questions. When considering point values for questions, students significantly outperform ChatGPT with a 76.7 percent average on assessments compared to 47.5 percent for ChatGPT if no partial credit is awarded and 56.5 percent if partial credit is awarded. Still, ChatGPT performs better than the student average for 15.8 percent of assessments when we include partial credit. We provide evidence of how ChatGPT performs on different question types, accounting topics, class levels, open/closed assessments, and test bank questions. We also discuss implications for accounting education and research.

This paper describes an innovative and simple technique to synthesize anisotropic nanostructures of both lithium niobate (LiNbO 3 ) and niobium oxide (Nb 2 O 5 ). These materials were obtained using a solution-phase non-hydrolytic decomposition of LiNb(OPr i ) 6 with or without the presence of Nb and Li-chlorides. The stability of LiCl is suggested as an explanation for the lack of LiNbO 3 production in the chloride-based reaction. After 2 and 24 hours of reaction crystalline products of Nb 2 O 5 and LiNbO 3 are obtained without further thermal treatment. The products of both reactions contained a mixture of spherical and rod-like morphologies. Larger crystals of LiNbO 3 and Nb 2 O 5 were predominantly found to be anisotropic with aspect ratios of 7:1 and 3:1, respectively. These structures are believed to result from the natural anisotropy of the unit cell for these materials and from the use of triphenylphosphine oxide (TPPO) as a coordinating solvent. Our solution-phase synthesis is easily scaled-up as a one-pot procedure that offers a promising route to controlling crystal size and morphology. Details of the composition and the growth of our LiNbO 3 and Nb 2 O 5 nanostructures will be discussed in addition to the details of our experimental procedure.

The volume of electrolyte used in commercial cylindrical rechargeable Li-ion batteries needs to be closely controlled to optimize performance. It is widely reported in the open literature that insufficient electrolyte can negatively impact cycling performance. However, there are scant reports showing the impact of excessive amounts of electrolyte on cell performance. Here, we show that adding excessive amounts of electrolyte also negatively impacts the cycling performance, causing cells to show faster capacity fade. The effect can be quite significant, causing a noticeable difference within the first 30 cycles, particularly at higher discharge rates (e.g., 1C to 2C rates, Figure 1). It is important to understand the causes of this “high-volume effect” because it sets an additional constraint on the optimization of the system. We have carried out extensive electrochemical impedance measurements of commercial 3.5 Ah 18650 cylindrical cells with various levels of electrolyte (LiPF6/EC/DMC/EMC; 15/25/56/4 wt%) using PEIS and GEIS protocols at an ambient temperature of 25°C. The collected impedance patterns exhibit typical two loop features reported in the literature 1,2 and were modelled by a series combination of one resistance and two parallel R/C elements to extract the cell ohmic and charge transfer resistance values. The total cell resistance of cells with both nominal and high-volume electrolyte show impedance growth during cycling. However, the high-volume cell shows noticeably higher growth of charge transfer resistance. Details of the experimental work and possible mechanism of this effect will be discussed during the presentation. References N. Ogihara et al., J. Electrochem. Soc., 159, A1034–A1039 (2012). W. Waag, S. Käbitz, and D. U. Sauer, Appl. Energy, 102, 885–897 (2013). Figure 1

Effects of electrolyte degradation on cell performance and corrosion of cell components, e.g. current collectors, are topics that have been reported in the literature.1,2 Recently, it has been reported that water contamination of LiPF6 liquid electrolytes can lead to salt degradation, generating difluorophosphoric acid (DFPH) and hydrofluoric acid (HF).3 With strict quality control of the moisture content in individual components and the use of dryroom conditions for cell assembly the risk of moisture contamination can be practically eliminated. When moisture is allowed to enter the cell in controlled research samples, dark stains indicative of pitting type corrosion have been observed on the inside of mild steel cans that are used to house cylindrically wound electrodes (see Figure 1 inset). Motivation to understand the underlying corrosion mechanism and the influential factors is important to help lower the risk of occurrence in manufacturing further. The use of a simple corrosion plate cell to study the susceptibility of a mild steel sample immersed in a LiPF6/EC/DMC (15/25/60 wt%) electrolyte will be discussed, with a focus on measured corrosion potentials, E corr, and current densities, j corr, extracted from the Tafel region of a potentiodynamic scan. Observations on the influence of acid degradation products in the electrolyte on the corrosion susceptibility of the mild steel will be discussed and applied to study select electrolyte additives previously reported in literature. Early results have shown that additives that scavenge HF and/or water directly can effectively suppress j corr, as shown in Figure 1, whereas additives that increased DFPH generation had no apparent effect. References: [1] Myung, Hitoshi, and Sun. J. Mater. Chem., 2011, 21, 9891-9911. [2] Ma et al. J. Phys. Chem. Lett. 2017, 8, 5, 1072–1077 [3] Wiemers-Meyer, Winter, and Nowak. Phys. Chem. Chem. Phys., 2016, 18, 26595-26601. Figure 1: Bar graph of corrosion current, j corr, measured for a LiPF6/EC/DMC (15/25/60 wt%) control electrolyte with 2500 ppm of water contamination, as well as with ~2 wt% of an additive that formed more DFPH than the control, an additive that formed more DFPH and HF than the control, and an additive that scavenged HF. Inset: Optical image of the inside of a mild steel can disassembled after 14 days of 60°C storage at top of charge illustrating dark regions indicative of steel corrosion. Figure 1