The exploration of ideal electrode materials overcoming the critical problems of large electrode volume changes and sluggish redox kinetics induced by large ionic radius of Na+/K+ ions is highly desirable for sodium/potassium‐ion batteries (SIBs/PIBs) toward large‐scale applications. The present work demonstrates that single‐phase ternary cobalt phosphoselenide (CoPSe) in the form of nanoparticles embedded in a layered metal–organic framework (MOF)‐derived N‐doped carbon matrix (CoPSe/NC) represents an ultrastable and high‐rate anode material for SIBs/PIBs. The CoPSe/NC is fabricated by using the MOF as both a template and precursor, coupled with in situ synchronous phosphorization/selenization reactions. The CoPSe anode holds a set of intrinsic merits such as lower mechanical stress, enhanced reaction kinetics, as well as higher theoretical capacity and lower discharge voltage relative to its counterpart of CoSe2, and suppressed shuttle effect with higher intrinsic electrical conductivity relative to CoPS. The involved mechanisms are evidenced by substantial characterizations and density functional theory (DFT) calculations. Consequently, the CoPSe/NC anode shows an outstanding long‐cycle stability and rate performance for SIBs and PIBs. Moreover, the CoPSe/NC‐based Na‐ion full cell can achieve a higher energy density of 274 Wh kg−1, surpassing that based on CoSe2/NC and most state‐of‐the‐art Na‐ion full cells based on P‐, Se‐, or S‐containing binary/ternary anodes to date.
Weak van der Waals interactions between interlayers of two‐dimensional layered materials result in disabled across‐interlayer electron transfer and poor layered structural stability, seriously deteriorating their performance in energy applications. Herein, we propose a novel covalent assembly strategy for MoS2 nanosheets to realize unique MoS2/SnS hollow superassemblies (HSs) by using SnS nanodots as covalent linkages. The covalent assembly based on all‐inorganic and carbon‐free concept enables effective across‐interlayer electron transfer, facilitated ion diffusion kinetics, and outstanding mechanical stability, which are evidenced by experimental characterization, DFT calculations, and mechanical simulations. Consequently, the MoS2/SnS HSs exhibit superb rate performance and long cycling stability in lithium‐ion batteries, representing the best comprehensive performance in carbon‐free MoS2‐based anodes to date. Moreover, the MoS2/SnS HSs also show excellent sodium storage performance in sodium‐ion batteries.
A novel high-performance gel polymer electrolyte (GPE) based on an electrospun polymer membrane of poly(vinylidene fluoride)/ poly(propylene carbonate) (PVdF/PPC) was prepared and investigated for high-performance lithium-ion battery applications. This study presents a methodology for introducing PPC into PVdF-based GPEs designed for highperformance lithium-ion batteries. SEM images and porosity measurements showed that the electrospun membrane had a uniform and highly interconnected porous structure with an average fiber diameter of 300−850 nm. Such a morphology resulted in excellent electrolyte uptake amount (500 wt %) and retention in PVdF/PPC membrane. The DSC result indicated that the PVdF crystallinity was deteriorated by the incorporation of PPC. The PVdF/PPC electrospun membrane showed significantly higher ionic conductivity (4.05 mS•cm −1 ) than that of the PVdF electrospun membrane (2.11 mS•cm −1 ) at 30 °C. The PVdF/PPC GPE was stable at a potential higher than 5.2 V (versus Li + /Li). The capacity of Li/ CGE-20/LiFePO 4 was 160, 151, 133, 119, and 102 mAh g −1 at a charge/discharge rate of 0.1, 0.2, 0.5, 1, and 2 C, respectively.
To overcome inferior rate capability and cycle stability of MnO-based materials as a lithium-ion battery anode associated with the pulverization and gradual aggregation during the conversion process, we constructed robust mesoporous N-doped carbon (N-C) protected MnO nanoparticles on reduced graphene oxide (rGO) (MnO@N-C/rGO) by a simple top-down incorporation strategy. Such dual carbon protection endows MnO@N-C/rGO with excellent structural stability and enhanced charge transfer kinetics. At 100 mA g, it exhibits superior rate capability as high as 864.7 mAh g, undergoing the deep charge/discharge for 70 cycles and outstanding cyclic stability (after 1300 cyclic tests at 2000 mA g; 425.0 mAh g remains, accompanying merely 0.004% capacity decay per cycle). This facile method provides a novel strategy for synthesis of porous electrodes by making use of highly insulating materials.
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