A high‐efficiency solution‐processed inverted perovskite solar cell with poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)benzidine] (poly‐TPD) as the hole transport layer is demonstrated. The perovskite forms large crystallites on poly‐TPD, yielding devices with an average power conversion efficiency of 13.8% and a maximum of 15.3%.

In this paper, we explore the relationship between the nanoscale structure and electrochemical performance of nanoscale scrolls of vanadium oxides (vanadium oxide nanorolls). The vanadium oxide nanorolls, which are synthesized through a ligand‐assisted templating method, exhibit different morphologies and properties depending upon the synthetic conditions. Under highly reducing conditions, nearly perfect scrolls can be produced which have essentially no cracks in the walls (well‐ordered nanorolls). If the materials are produced under less reducing conditions, nanorolls with many cracks in the oxide walls can be generated (defect‐rich nanorolls). Both types of samples were examined by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and X‐ray photoemission spectroscopy (XPS) to characterize their local structure, local redox state, and nanoscale structure. After ion‐exchange to replace the templating ammonium ions with Na+, the ability of these materials to electrochemically intercalate lithium reversibly was investigated. In sweep voltammetry experiments, the well‐ordered nanorolls showed responses similar to those seen in crystalline orthorhombic V2O5. In contrast, the defect‐rich vanadium oxide nanorolls behaved electrochemically more like sol–gel‐prepared vanadium oxide materials. Moreover, the specific capacity of the well‐ordered nanorolls was about 240 mA h g–1 while that of the defect rich nanorolls was found to be as much as 340 mA h g–1 under these same conditions. Disorders on both the atomic and nanometer length scales are believed to contribute to this difference.

Vehicle-to-grid (V2G) and Grid-to-vehicle (G2V) strategies are often cited as promising approaches to mitigate the intermittency of renewable energy on electric power grids. However, their impact on vehicle battery degradation have yet to be investigated in detail. Since battery degradation is path dependent, i.e. different usage schedules lead to different degradation mechanisms, it is essential to investigate batteries under realistic V2G and G2V scenarios. The aim of this work is to understand the effect of bidirectional charging on the degradation mechanisms of commercial Li-ion cells used in electric vehicles today. Results showed that an extra V2G step during cycle-aging accelerated capacity loss and degraded the kinetics at the negative electrode. Moreover, for all cycling duty cycles, the loss of active material at the negative electrode was higher than the loss of lithium inventory. This condition could trigger lithium plating and shorten cell lifetimes. In the calendar-aging experiments, state of charge was shown to be an important factor and interacted with temperature to accelerate the loss of active material at the positive electrode and the loss of lithium. It was also found that high state of charge values caused loss of active material at the negative electrode and kinetic limitations.

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Automobile dependency and the inexorable proliferation of electric vehicles (EVs) compels accurate predictions of cycle life across multiple usage conditions and for multiple lithium-ion battery systems. Synthetic driving cycles have been essential in accumulating data on EV battery lifetimes. However, since battery deterioration is path-dependent, the representability of synthetic cycles must be questioned. Hence, this work compared three different synthetic driving cycles to real driving data in terms of mimicking actual EV battery degradation. It was found that the average current and charge capacity during discharge were important parameters in determining the appropriate synthetic profile, and traffic conditions have a significant impact on cell lifetimes. In addition, a stage of accelerated capacity fade was observed and shown to be induced by an increased loss of lithium inventory (LLI) resulting from irreversible Li plating. New metrics, the ratio of the loss of active material at the negative electrode (LAMNE) to the LLI and the plating threshold, were proposed as possible predictors for a stage of accelerated degradation. The results presented here demonstrated tracking properties, such as capacity loss and resistance increase, were insufficient in predicting cell lifetimes, supporting the adoption of metrics based on the analysis of degradation modes.

Three-dimensional nanometer-scale quantification of all species is made around grain boundaries in Nd-doped CeO2allowing three-dimensional determination of electrostatic potentials.

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Abstract:The use of lithium batteries for power and energy-hungry applications has risen drastically in recent years. For such applications, it is necessary to connect the batteries in large assemblies of cells in series and parallel. With a large number of cells operating together, it is necessary to understand their intrinsic variabilities, not only at the initial stage but also upon aging. In this study, we studied a batch of commercial cells to address their initial cell-to-cell variations and also the variations induced by cycling. To do so, we not only tracked several metrics associated with cell performance, the maximum capacity, the resistance, and the rate capability but also the degradation mechanism via a non-invasive quantification of the loss of lithium inventory (LLI), the loss of active material (LAM) and the kinetic degradation on both electrodes. We found that, even with small initial cell-to-cell variations, significant variations will be observed upon aging because the cells degrade at a different pace. We also observed that these variations were not correlated with the initial variations.