查看更多>>摘要：? 2022 Elsevier B.V.To achieve wide applications of LiCoO2-based high-voltage lithium-ion batteries, three questions remain to be answered: how to stabilize the cathode/electrolyte interphase upon cycling, what is the practical performance at the pouch cell level and various temperatures, and why the charge cutoff voltage is limited at 4.4 V. Thus, an ~3 Ah LiCoO2/artificial graphite pouch cell has been developed, whose performances at different temperatures and voltages have been studied. It is observed that the cell at 4.5 V exhibits ultrahigh area capacity and energy-density, good discharge abilities at high rates and at ? 20 °C, and high cyclic stability. Investigation reveals that the bulk structure and interface of LiCoO2 are stabilized by using LiCoO2, which is composed of monocrystalline and polycrystalline powders, and a combination of multiple electrolyte additives. We also find that the real barriers for a commercial application are the inferior high-rate charge ability due to the aggravated electrochemical polarization and poor storage stability at 60 °C caused by the side reactions. Undoubtedly, this work will deepen the understanding of the overall performance of LiCoO2-based high-energy-density pouch cells and direct further optimization of LiCoO2.
查看更多>>摘要：? 2022 Elsevier B.V.CsPbI3 all-inorganic perovskite has now drawn much attention due to its superior thermal stability compared with the organic-inorganic hybrid counterparts. Despite the great progress achieved recently in this field, CsPbI3 still suffers from low phase stability when exposed to moisture. We found the phase transition of CsPbI3 would be accelerated after depositing the conventional hole transport material (HTM) 2,2′,7,7′-Tetrakis[N,N-di(4-methoxyphenyl)amino]? 9,9′-spirobifluorene (spiro-OMeTAD). This is attributed to the negative effects of the additives in spiro-OMeTAD HTM: the hydrolysis of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), the corrosivity of 4-tert-butylpyridine (TBP), and the evaporation of TBP. By slightly modifying the additive content, full coordination between LiTFSI and TBP could be achieved and the negative effects mentioned above could be mitigated. Furthermore, tris(2-(1 H-pyrazol-1-yl)? 4-tert-butylpyridine)cobalt(III)-tris(bis(trifluoromethylsulfonyl)imide) (Co(III)TFSI) was added to promote oxidation of spiro-OMeTAD HTM in inert environment. With these approaches of additive engineering, HTMs with better interface contact and charge transport capability could be obtained. The device with optimized spiro-OMeTAD HTM achieved a champion power conversion efficiency (PCE) of 10.61% compared with 6.63% of the control one. Moreover, the optimal device maintained 81% of its initial PCE after storage for 30 days, exceeding that (68%) of the control one. Our results highlight the importance of spiro-OMeTAD HTM on the stability of CsPbI3 all-inorganic perovskite and provide a facile and feasible way to increase the stability and performance of corresponding solar cells.
查看更多>>摘要：? 2022 Elsevier B.V.For metal oxide gas sensors, the upstream theoretical mechanism can provide both quantum guidance for screening favorable materials and important insights in fabricating electronic devices. However, except for widely popular Yamazoe's ‘receptor-transducer-utility’ model, some specific theoretical models still lack for diverse sensing properties of metal oxide semiconductor currently. Based on a deeper understanding of surface catalytic mechanism, n-type SnO2 was selected as an example to screen a better solution. Herein, hierarchical SnO2 microcubes assembled from cross-stacked nanoslices were synthesized via a self-templated method, and the SnO2 microcubes displayed versatile performances with excellent response to 100 ppm ethanol (Sr = Rair/Rgas = 56.9), relative low optimal working temperature of 170 °C, good repeatability under high R.H. (90%) and ultra-low detection limit even under 0.1 ppm. The performances of SnO2 nanofilms, hierarchical SnO2 nanotubes and commercial SnO2 powder were also studied. The results showed that the increase of exposed higher energy facet of (101) and rich oxygen vacancies on 3D-crossed nanoslices of SnO2 microcubes contribute to outstanding gas sensing performances, which were also confirmed by the DFT calculations. These demonstrate a diverse sensing mechanism and a new insights for state-in-art gas sensing materials of SnO2.
查看更多>>摘要：? 2022 Elsevier B.V.A series of nano-V1-xMnxO2 samples (x = 0–0.035) were prepared by a simple solvothermal method. XRD patterns and the Rietveld refinement results of V1-xMnxO2 samples showed that Mn ions were incorporated into the V sites during the solvothermal process. XPS results indicated that the valence state of Mn ion was a mixed state of Mn2+, Mn3+ and Mn4+. The corresponding relationship between the diameter, specific surface area and electrochemical performances of V1-xMnxO2 nanorods was studied. It can be found that Mn doping promoted the insertion of K+ ions into the electrode material and improved the conductivity, discharge capacity and cycle stability, which was due to more defects induced by Mn doping. The x = 0.020 sample had the largest specific capacitance (the 88% capacity retention rate after 550 cycles at 0.1 A·g?1) due to the improvement of structural stability by Mn-ion doping. These results provide great potential applications for nano-VO2(B) in the cathode material of lithium-ion battery and supercapacitor.
查看更多>>摘要：? 2022 The AuthorsSilicon is a promising alternative anode material for lithium-ion batteries (LIBs), offering a high theoretical capacity and low working potential versus Li+/Li. However, massive volume changes during the Li+ charge/discharge process and the low intrinsic conductivity of Si are limiting factors for its practical applicability in energy storage systems. In this study, transition metal (Mn, Ni)-doped silicon nanoparticles (Si NPs) with different dopant concentrations were prepared using a low-temperature heat treatment approach and studied as anode materials for LIBs. Compared to pure Si anodes, transition metal-doped Si anodes showed improved electrochemical performance. After 100 cycles, 0.5% Mn- and 0.5% Ni-doped Si anodes delivered 2324 mA h g–1 and 2561mA h g–1 with 88% and 86% capacity retention, respectively, at 200 mA g–1 (vs. first reversible capacity). The prepared anodes exhibited a superior rate capability and better Li+ diffusion properties. These significant enhancements in the electrochemical properties are attributed to the metal dopant, which enhances the intrinsic conductivity of the host Si and mitigates volume expansion. Moreover, it provides the required ionic channels for faster Li+ diffusion while reducing the Li+ diffusion length across the host Si. The full cells fabricated from the prelithiated metal-doped Si anodes and commercial LiCoO2 cathodes delivered high energy densities of 371 Wh kg–1 and 388.5 Wh kg–1, respectively, and were found to be suitable for Li+ energy storage applications.
查看更多>>摘要：? 2022 The AuthorsThis work address the issue of spectral implications provided by doping AgInS2 QDs with Zn2+ and its higher homologues including Cd2+ and Hg2+. The impact of alloying AgInS2 QD with IIB group atoms is here discussed in terms of comprehensive spectroscopic measurements as well as theoretical predictions performed within the Density Functional Theory. It is shown that each of the admixtures used induces a completely different spectral response including complete reversal character for Cd2+ and Hg2+ ions. Observed differences were here associated with changes in the native defects structure and possible relaxation pathways due to doping. It is shown that Zn2+ ions results in quite weak impact on the emission properties of the AgInS2 QDs. Highest impact was found for Cd2+ and Hg2+ ions. Doping AgInS2 QDs with Cd2+ results in successive deactivation of the relaxation pathways which were typical for pristine AgInS2 QDs leading to significant shortening of the photoluminescence lifetime and partial band symmetrisation. Doping with Hg2+ ions was found to be of completely opposite character. It was found that mercury adatom has the lowest affinity to the AgInS2 surface giving rise to formation of metallic Hg-Ag complexes on a surface which may be responsible for anomalous behaviour of Hg-doped AgInS2 QDs.
查看更多>>摘要：? 2022 Elsevier B.V.The dual phase PtAl2-dispersed (Ni,Pt)Al coating (DP coating) and single phase (Ni,Pt)Al coating (SP coating) have been prepared simultaneously with an intermediate Pt content at the surface before low-activity high-temperature aluminizing process. Hot corrosion and cyclic oxidation performance of these two Pt-modified coatings are investigated in comparison with unmodified NiAl coating (UM coating). The results show that DP coating displays better hot corrosion resistance than SP and UM coating due to its higher Al content and faster Al diffusion rate in PtAl2 phase. The cyclic oxidation resistance of DP coating is comparable to SP coating, while lighter rumpling is achieved at the surface of DP coating. This is because the volume change accompanied by phase transformation from ζ-PtAl2 to β-(Ni,Pt)Al in DP coating is less than that from β-(Ni,Pt)Al to γ’-Ni3Al in SP coating. Moreover, ζ-PtAl2 is superior to β-(Ni,Pt)Al in creep resistance, which also qualifies DP coating with less rumpling than SP coating with the same residual stress.
查看更多>>摘要：? 2022 Elsevier B.V.Hard carbon with high specific capacity and cost-effective characteristics has emerged as a critical material in the study of sodium-ion batteries (SIBs) anodes. However, their unsatisfactory initial coulombic efficiency (ICE) and ineluctable structural deformation during long-cycling work seriously hinder their application in practice. Here, phosphorus/sulfur co-doped hard carbon with a porous bowl-like structure (denoted as P/S-HCB) is developed to achieve high performance. The experimental data show that the doping of S increased the interlayer spacing of graphite in the surface/subsurface region, the doping of P promoted the formation of C-S-P and P-O bonds, which can contribute to abundant structural defects and redox reaction sites that not only improves structural stability but also contributes to the capacitive process under high rate. The as-fabricated P/S-HCB electrode demonstrates outstanding Na-ion storage performance regarding high ICE of 88.71%, the high-reversibility capacity of about 450 mA h g?1 after 140 cycles at 0.2 A g?1, extraordinary rate capability of 216.3 mA h g?1 at 10 A g?1, and long-term cycling stability of 276 mA h g?1 after 3000 cycles at 10 A g?1. These results show a novel approach to developing advanced hard carbon materials for sodium storage.
查看更多>>摘要：? 2022 Elsevier B.V.In order to broaden the spectral response range of graphitic carbon nitride (g-C3N4) and improve its visible-light catalytic activity, the method of ethanol-assisted solvo-thermal pretreatment and subsequent polymerization was used to prepare Bi/γ-Bi2O3 nanoparticles modified O-doped g-C3N4 (Bi/γ-Bi2O3/EtCN). During the polymerization of g-C3N4, oxygen doping brought about a richer pore structure, while ethanol and urea promoted the formation of sub-stable γ-Bi2O3, and most importantly, these reactions were achieved simultaneously to successfully fabricate the all-solid Z-scheme structure. The obtained Bi/γ-Bi2O3/EtCN showed much higher activity in the visible-light photocatalytic degradation of bisphenol A (BPA) than that of g-C3N4 and EtCN, where the degradation rate of 0.03Bi/γ-Bi2O3/EtCN was 15.67 times higher than that of g-C3N4, showing excellent visible photocatalytic performance. The improvement of the activity of Bi/γ-Bi2O3/EtCN mainly caused by the formation of all-solid Z-scheme heterojunction between γ-Bi2O3 and EtCN with Bi as the electron shuttle, which broadened the light absorption range of the catalyst, promoted the effective separation of electron-hole pairs. It was also found that ?O2? played a major role and h+ played a secondary role during BPA degradation process using 0.03Bi/γ-Bi2O3/EtCN as the photocatalyst, which confirmed the mechanism of Z-scheme heterojunction.
查看更多>>摘要：? 2022 Elsevier B.V.In recent years, low-cost spinel sulfides as counter electrode materials for quantum dot sensitized solar cells (QDSSCs) have gradually become a research hotspot in this field. In this study, CuCo2S4/reduced graphene oxide (RGO) composite is successfully prepared via a simple and low-cost solvothermal method, which was used as counter electrode (CE) and assembled with CdS/CdSe photoanode to form QDSSCs device. In comparison with other materials, the power conversion efficiency of CuCo2S4/RGO CE reaches 6.59% and is conspicuously superior to that of pure CuCo2S4 and Cu2S/brass CE, benefiting from that the peculiar structure of the CuCo2S4 hollow spherical shell loaded on RGO nanosheets shortens electron migration paths and enables efficient transportation of electrons. Furthermore, the corrosion resistance of CEs has been prominently enhanced compared with Cu2S/brass CE. Thus, CuCo2S4/RGO composite can be primely acknowledged as promising CE materials for competitive high-performance QDSSCs and offer the possibility for high efficiency and energy saving of QDSSCs in the future.
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