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The crystal structure and electrocatalytic performance of Ni-based MOFs were controlled by the symmetrical engineering of Br functional groups on the terephthalic acid ligand. The asymmetric coordination between metal active sites and the ligand makes Ni-DBC-1Br an excellent OER electrocatalyst with a significantly lower overpotential (247 mV) accompanied by a low Tafel slope of 58.1 mV dec−1 in 1 M KOH (pH = 13.88). [ABSTRACT FROM AUTHOR]

This study investigated the influence of green manure planting on the spectroscopic properties of dissolved organic matter (DOM) in saline–alkali soil under freshwater leaching conditions at different soil depths. The UV254, UV253/UV203, α300, α355, SUVA254, SUVA260, and SR ultraviolet parameters indicated reductions in the content of large molecular substances, benzene ring substitution degree, colored dissolved organic matter, aromaticity, and hydrophobic components in the soil leachate DOM with an increasing soil depth. Compared with the non-green manure treatment control, green manure planting mitigated the leaching of dissolved organic matter in soil during saline irrigation, with rape green manure demonstrating superior effectiveness. Utilizing three-dimensional fluorescence combined with parallel factor analysis, this study analyzed three fluorescent components of soil leachate DOM: C1 (visible-light fulvic acid), C2 (humic acid), and C3 (tyrosine-like protein). The combined contribution of the two humic substance components (C1 + C2) was approximately 70%, indicating the dominance of humic substances in leachate DOM. The fluorescence parameters of soil leachate DOM included an average of the fluorescence index (FI) values between 1.4 and 1.9, low humification index (HIX) values consistently below 4, and biological index (BIX) values ranging from 0.8 to 1.0, suggesting a mixed source, low humification degree, poor stability, and moderate self-source characteristics. Compared with the non-green manure treatment control, both the green manure treatments exhibited a relatively higher proportion of biogenic sources and humification degree in soil leachate DOM. This suggests that planting green manure can reduce the relative DOM content under freshwater leaching conditions, increase the proportion of biogenic sources in soil leachate DOM, and enhance soil humification. Planting rapeseed green manure can diminish the leaching of DOM from land sources and augment soil humification. [ABSTRACT FROM AUTHOR]

The spinel LiNi0.5Mn1.5O4 cathode material was synthesized via a metal–organic frameworks (MOFs) method followed by high-temperature calcination. The effects of the solvent molecular chain length on the structure, morphology, and electrochemical properties of the MOF precursors and LiNi0.5Mn1.5O4 materials were investigated. The results show that the content of Mn3+, the size of MOF precursors, and LiNi0.5Mn1.5O4 particle gradually decreases with the increasing of solvent molecular chain length. Among them, the LNMO-EG sample exhibits superior electrochemical performance, the discharge capacity retention of 96.1% after 200 cycles at 1C rate, at a high rate of 5C, it still delivers a capacity of 120.8 mAh g−1 and capacity remains 85.2% after 500 cycles. These improvements might be due to the synergistic effect of moderate particle size, high Mn3+ content, and low impurity content, which avoids material agglomeration during long-term cycling and promotes the diffusion of Li+ during the interaction/deinteraction process. [ABSTRACT FROM AUTHOR]

H3PO4 pretreated and Li3PO4 coated Li-rich materials Li1.2Ni0.2Mn0.6O2 have been prepared via hydrothermal followed by a facile modified method. The pretreated process partially extracts Li and O from lattice, results in pre-activation of Li2MnO3 component and the formation of spinel phase. A stable Li3PO4 coating is formed on the surface of the material during the subsequent heat treatment. H3PO4 pretreatment and Li3PO4 coating are skillfully combined using a simple method. Electrochemical studies exhibit that the electrochemical performance of Li1.2Ni0.2Mn0.6O2 is obviously improved after surface modification. The surface treated material with 0.04 mol L−1 H3PO4 shows more excellent electrochemical properties than those of Li1.2Ni0.2Mn0.6O2 cathode, with a high specific discharge capacity of 262.6 mAh g−1 at 0.1 C, a great capacity retention of 92.2% at 1 C after 100 cycles, and an outstanding rate capability reaching 105.4 mAh g−1 at 10 C. The enhanced performance is caused by the formation of spinel phase and Li3PO4 coating layer, which can accelerate the migration of Li+ and facilitate the charge transfer reaction. The Li3PO4 coating also inhibits the dissolution of transition metal ions and enhances the stability of electrode/electrolyte interface. [ABSTRACT FROM AUTHOR]

Spinel LiNi0.5Mn1.5O4(LNMO) cathode with high voltage plateau at around 4.7 V (vs. Li/Li+) has attracted great attention. While the unsatisfactory electrochemical performance at high voltage hinders its practical application in next generation lithium ion batteries. Based on our previous research, FEC as electrolyte additive significantly improves the electrochemical performance of high voltage LNMO cell. The LNMO/Li cell with 4 wt% FEC shows the best rate capability, 76% capacity retention even at 5C. And the high temperature cycling performance of LNMO/G full cell with FEC is improved. The result from Raman indicates that FEC can transform the association structure of AGGs in the electrolytes to the salvation structure of SSIPs which increases the conductivity of electrolyte. EIS, SEM, TEM, XPS and FTIR analyses indicate that a more stable CEI film has been formed on the cathode surface with appropriate FEC as additive, which can promote the transport of lithium ions and inhibit the dissolution of transition metal elements. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate and manganese oxide (PEDOT:PSS/MnO2) hybrids were prepared via a facile solvothermal method coupled with an oxidative polymerization route. The effects of the reaction temperature and the KMnO4-to-organic monomer (3,4-ethylenedioxythiophene, EDOT) ratio on the morphology, structure, and electrochemical properties of the materials were investigated. The optimized composites comprised homogeneous nanorod-like structures and exhibited overwhelmingly high conductivity (36 S cm−1) and superior supercapacitance—more specifically, they exhibited high-rate capability. The electrochemical properties of the nanocomposites were investigated using cyclic voltammetry and galvanostatic charge-discharge cycling. The prepared hybrids showed a high capacitance of 365.5 F g−1 at a current density of 1 A g−1, a good rate performance of 325.4 F g−1 at 20 A g−1 (capacitance retention of 89%), and excellent cycling stability with approximately 80% capacitance retention after 2000 cycles at a current density of 5 A g−1 in a 6 M KOH aqueous electrolyte. [ABSTRACT FROM AUTHOR]

Abstract Traditional approaches to recycle and regenerate spent lithium-ion batteries by leaching are polluted and complicated. In this study, a green and simple technique has been provided to regenerate spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode material, besides, the regenerated mechanisms are investigated. Studies indicate that lost lithium ions in material lattice are replenished by added lithium, meanwhile, insulting impurities on particle surface remove basically, cracked and broken particles disappear during the regeneration process. Electrochemical tests demonstrate that the performances of regenerated material improve significantly. The discharge capacities are 164.6 mAh g−1 at 0.1 C rate and 147 mAh g−1 at 1 C rate, respectively. They still could deliver a discharge capacity of 131 mAh g-1 with a high capacity retention rate of 89.12% after 100 cycles at 1 C, which can be considered as a preferable electrical energy storage system. The improved electrochemical performances prove a facial and effective regeneration process. [ABSTRACT FROM AUTHOR]