The accuracy and connection mode of the equivalent model of retired power battery cells will affect the size of the combined capacity. To this end, this article analyzes series-parallel combination capacity of retired power batteries. First, because an accurate single equivalent circuit model of retired power batteries is necessary for the capacity analysis of the combination, the forgetting factor recursive least squares (FFRLS) algorithm is used to identify the parameters of the model, and the second-order RC equivalent circuit is selected as the single equivalent circuit model of retired power battery. Then the equivalent circuit model is used as the basis, respectively constructing first-parallel-before-series and first-series-before-parallel power battery combination, and fully and unequally arranged the retired power batteries under the two assemblies. Finally, the capacity and distribution characteristics of the two combinations under different arrangements are verified by simulation. The results show that no matter how the arrangement is changed, the maximum capacity of the first-parallel-before-series retired power battery combination is always better than the first-series-before-parallel combination, and the distribution position of the single retired battery in both combinations under the maximum combination capacity is obtained.
All-solid-state batteries experience irreversible capacity loss particularly in the initial potential cycle, owing to electrolyte decomposition at the electrode/electrolyte interface. A strategy for expanding the oxidation stability of electrolytes is replacing the anion with fluorine. However, fluorine substitution has a negative influence on ionic conductivity. In this study, we introduced trace amounts of fluorine into Li3YCl6 solid electrolytes which exhibit high ionic conductivities and wide potential windows. The effect of replacement on ionic conductivity, oxidation stability, and charge–discharge characteristics were studied. The trace amounts of fluorine in Li3YCl6 did not reduce the conductivity, but improved the apparent oxidation stability. The decomposed product of LiF from the fluorine-substituted electrolyte disturbed the formation of a high-resistance layer at the electrode/electrolyte interface. The initial charge–discharge efficiency of the uncoated LiCoO2 cathode was improved by the trace amount of fluorine replacement in the Li3YCl6 solid electrolyte.
Perovskite oxides obtained from Ba1−xLaxFeO3−δ (BLF) are considered beneficial materials for electrodes of solid oxide fuel cells and oxygen permeation membranes because of their high oxygen permeability, which is a criterion of oxide ion (O2−)-electronic mixed conductivity. In this paper, the prime focus was to understand the oxygen permeation mechanism through surface exchange and bulk diffusion of the Ba0.5La0.5FeO3−δ (BLF55) sample. The permeated oxygen flux displayed higher than that of the typical mixed conductor La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF), which was explored simultaneously with corresponding oxygen chemical potentials employing an especial experimental setup. This study found that the surface exchange reaction on the oxygen-lean side was the rate-determining step (RDS) of the oxygen permeation below 800 °C, resulting from lower hole concentration on the oxygen-lean side surface. Enhancing the charge transfer from the surface oxygen by increasing hole concentration is a prime important strategy to improve the surface exchange reaction.
A lithium-excess cation-disordered rocksalt oxide, Li1.15Nb0.15Mn0.7O2, is synthesized and tested as positive electrode materials for battery applications. Although nanosized Li1.15Nb0.15Mn0.7O2 delivers a large reversible capacity using cationic/anionic redox reaction, the inferior capacity retention hinders its use for practical applications. Such degradation of electrode reversibility, including electrochemical and structural reversibility, is anticipated to originate from the gradual oxygen loss for the electrode materials with anionic redox. Herein, Li3PO4 is integrated into Li1.15Nb0.15Mn0.7O2 by high-energy mechanical milling, and 7 mol% Li3PO4 integrated Li1.15Nb0.15Mn0.7O2, Li1.2P0.06Nb0.13Mn0.61O2, shows much improved cyclability when compared with the sample without Li3PO4. Approximately 80 % of reversible capacity is retained after 100-cycle test at a rate of 200 mA g−1. Moreover, electrode kinetics are significantly improved by Li3PO4 integration, and Li1.2P0.06Nb0.13Mn0.61O2 delivers a discharge capacity of 200 mA h g−1 at a rate of 640 mA g−1. Li1.2P0.06Nb0.13Mn0.61O2 also shows improved thermal stability at elevated temperatures. From these results, the effectiveness of Li3PO4 integration into nanosized disordered rocksalt oxides with anionic redox is discussed, and this finding leads to the development of metastable high-capacity positive electrode materials for advanced Li-ion batteries.
All-solid-state batteries (ASSBs) using sulfide solid electrolytes (SEs) are attractive candidates as next-generation energy devices having longer lifetimes than liquid-type lithium-ion batteries (LIBs) using organic solvents. Sulfide SEs are known that to suffer a decrease in their ionic conductivity and generate toxic hydrogen sulfide when exposed to moisture even in an environment such as in a dry room. However, the influence of the exposure to moisture on the ASSB cell performance has not been fully elucidated so far. Aiming at filling this gap of knowledge, this paper describes the investigation of the influence of moisture on the durability of an ASSB positive electrode with sulfide SE unexposed or exposed to dry-room-simulated air with dew point of −20 °C in this study. After the cell durability evaluation, time-of-flight secondary-ion mass spectrometry (ToF-SIMS) measurements were performed on positive electrode, and a characteristic degradation mode was observed in the cell using the exposed SE.
Fluoride shuttle batteries are expected to be innovative with high energy density superior to lithium-ion ones as on-board power-source for electric vehicles. However, the low solubility of fluoride ion in organic solvents makes it difficult to choose electrolytes. Kawasaki et al. have reported that no precipitation appears in γ-butyrolactone solution of CsF at high concentrations in the presence of excess amounts of Li+ or Mg2+ cation [M. Kawasaki, et al., J. Electrochem. Soc., 169, 110508 (2022).]. Such solutions are called hybrid electrolyte ones. In this study, we performed conductometric titration of Li+- or Mg2+-containing solutions with CsF solutions to elucidate the ion equilibrium. The titration curves were analyzed on models including precipitation of LiF or MgF2 and formation of Li2F+ and LiF2− triple ion or MgF+ associated one to evaluate the corresponding equilibrium constants. The results indicate that no precipitation appears in certain ranges of the F−/Li+ or F−/Mg2+ molar ratio by the triple/associated ion formation. Details of the conductometric analysis are discussed together with some problems involved in the proposed method.