查看更多>>摘要：The development of high-energy and long-lifespan NASICON-type cathode materials for sodium-ion batteries has always been a research hotspot but a daunting challenge.Although Na4MnCr(PO4)3 has emerged as one of the most promising high-energy-density cathode materials owing to its three-electron reactions,it still suffers from serious structural distortion upon repetitive charge/discharge processes caused by the Jahn-Teller active Mn3+.Herein,the selective substitution of Cr by Zr in Na4MnCr(PO4)3 was explored to enhance the structural stability,due to the pinning effect of Zr ions and the ≈2.9-electron reactions,as-prepared Na3.9MnCr0.9Zr0.1(PO4)3/C delivers a high capacity retention of 85.94％over 500 cycles at 5 C and an ultrahigh capacity of 156.4 mAh g-1 at 0.1 C,enabling the stable energy output as high as 555.2 Wh kg-1.Moreover,during the whole charge/discharge process,a small volume change of only 6.7％was verified by in situ X-ray diffraction,and the reversible reactions of Cr3+/Cr4+,Mn3+/Mn4+,and Mn2+/Mn3+redox couples were identified via ex situ X-ray photoelectron spectroscopy analyses.Galvanostatic intermittent titration technique tests and density functional theory calculations further demonstrated the fast reaction kinetics of the Na3.9MnCr0.9Zr0.1(PO4)3/C electrode.This work offers new opportunities for designing high-energy and high-stability NASICON cathodes by ion doping.
查看更多>>摘要：lonic-conductive solid-state polymer electrolytes are promising for the development of advanced lithium batteries yet a deeper understanding of their underlying ion-transfer mechanism is needed to improve performance.Here we demonstrate the low-enthalpy and high-entropy(LEHE)electrolytes can intrinsically generate remarkably free ions and high mobility,enabling them to efficiently drive lithium-ion storage.The LEHE electrolytes are constructed on the basis of introducing CsPbl3 perovskite quantum dots(PQDs)to strengthen PEO@LiTFSI complexes.An extremely stable cycling＞1000 h at 0.3 mA cm-2 can be delivered by LEHE electrolytes.Also,the as-developed Li|LEHE|LiFePO4 cell retains 92.3％of the initial capacity(160.7 mAh g-1)after 200 cycles.This cycling stability is ascribed to the suppressed charge concentration gradient leading to free lithium dendrites.It is realized by a dramatic increment in lithium-ion transference number(0.57 vs 0.19)and a significant decline in ion-transfer activation energy(0.14 eV vs 0.22 eV)for LEHE electrolytes comparing with PEO@LiTFSI counterpart.The CsPbl3 PQDs promote highly structural disorder by inhibiting crystallization and hence endow polymer electrolytes with low melting enthalpy and high structural entropy,which in turn facilitate long-term cycling stability and excellent rate-capability of lithium-metal batteries.
查看更多>>摘要：Searching for novel solid electrolytes is of great importance and challenge for all-solid-state Mg batteries.In this work,we develop an amorphous Mg borohydride ammoniate,Mg(BH4)2·2NH3,as a solid Mg electrolyte that prepared by a NH3 redistribution between 3D framework-γ-Mg(BH4)2 and Mg(BH4)2·6NH3.Amorphous Mg(BH4)2·2NH3 exhibits a high Mg-ion conductivity of 5 × 10-4 S cm-1 at 75 ℃,which is attributed to the fast migration of abundant Mg vacancies according to the theoretical calculations.Moreover,amorphous Mg(BH4)2·2NH3 shows an apparent electrochemical stability window of 0-1.4 V with the help of in-situ formed interphases,which can prevent further side reactions without hindering the Mg-ion transfer.Based on the above superiorities,amorphous Mg(BH4)2·2NH3 enables the stable cycling of all-solid-state Mg cells,as the critical current density reaches 3.2 mA cm-2 for Mg symmetrical cells and the reversible specific capacity reaches 141 mAh g-1 with a coulombic efficiency of 91.7％(first cycle)for Mg||TiS2 cells.
查看更多>>摘要：The growing demand for substitutes of lithium chemistries in battery leads to a surge in budding novel anion-based electrochemical energy storage,where the chloride ion batteries(CIBs)take over the role.The application of CIBs is limited by the dissolution and side reaction of chloride-based electrode materials in a liquid electrolyte.On the flipside,its solid-state electrolytes are scarcely reported due to the challenge in realizing fast Cl-conductivity.The present study reports[Al(DMSO)6]Cl3,a solid-state metal-organic material,allows chloride ion transfer.The strong Al-Cl bonds in AlCl3 are broken down after coordinating of Al3+by ligand DMSO,and Cl-in the resulting compound is weakly bound to complexions[Al(DMSO)6]3+,which may facilitate Cl-migration.By partial replacement of Cl-with PF6-,the room-temperature ionic conductivity of as-prepared electrolyte is increased by one order of magnitude from 2.172 × 10-5 S cm-1 to 2.012 × 10-4 S cm-1.When they are assembled with Ag(anode)/Ag-AgCl(cathode)electrode system,reversible electrochemical redox reactions occur on both sides,demonstrating its potential for solid-state chloride ion batteries.The strategy by weakening the bonding interaction using organic ligands between Cl-and central metallic ions may provide new ideas for developing solid chloride-ion conductors.
查看更多>>摘要：The redox couple of I0/I-in aqueous rechargeable iodine-zinc(12-Zn)batteries is a promising energy storage resource since it is safe and cost-effective,and provides steady output voltage.However,the cycle life and efficiency of these batteries remain unsatisfactory due to the uncontrolled shuttling of polyiodide(I3-and I5-)and side reactions on the Zn anode.Starch is a very low-cost and widely sourced food used daily around the world."Starch turns blue when it encounters iodine"is a classic chemical reaction,which results from the unique structure of the helix starch molecule-iodine complex.Inspired by this,we employ starch to confine the shuttling of polyiodide,and thus,the I0/I-conversion efficiency of an I2-Zn battery is clearly enhanced.According to the detailed characterizations and theoretical DFT calculation results,the enhancement of I0/I-conversion efficiency is mainly originated from the strong bonding between the charged products of I3-and Is-and the rich hydroxyl groups in starch.This work provides inspiration for the rational design of high-performance and low-cost I2-Zn in AZIBs.
查看更多>>摘要：Designing flexible free-standing air-electrode with efficient OER/ORR performance is of vital importance for the application of Zinc-air batteries in flexible electronics.Herein,a flexible free-standing electrode(Ni/Fe-NC/NCF/CC)is synthesized by in-situ coupling of binary Ni/Fe-NC nanocubes and N-doped carbon nanofibers(NCF)rooted on carbon cloth.The highly dispersed binary Ni/Fe-NC sites ensure excellent ORR activity and create efficient OER active sites relative to Ni-NC and Fe-NC.The in-situ coupling of Ni/Fe-NC and NCF constructs a 3D interconnected network structure that not only provides abundant and stabilized reactive sites but also guarantees fast electron transfer and gas transportation,thus achieving efficient and fast operation of ORR/OER.Therefore,Ni/Fe-NC/NCF/CC displays a much positive potential(0.952 V)at 4.0 mA cm-2 for ORR and a low OER overpotential(310 mV)at 50 mA cm-2.The Zinc-air battery with Ni/Fe-NC/NCF/CC air-electrode exhibits excellent battery performance with outstanding discharge/charge durability for 2150 cycles.The flexible Zn-air batteries with foldable mechanical properties display a high power density of 105.0 mW cm-2.This work widened the way to prepare flexible bifunctional air-electrode by designing composition/structure and in-situ coupling.
查看更多>>摘要：In recent years,the interest in the development of highly concentrated electrolyte solutions for battery applications has increased enormously.Such electrolyte solutions are typically characterized by a low flammability,a high thermal and electrochemical stability and by the formation of a stable solid electrolyte interphase(SEI)in contact to electrode materials.However,the classification of concentrated electrolyte solutions in terms of the classical scheme"strong"or"weak"has been controversially discussed in the literature.In this paper,a comprehensive theoretical framework is presented for a more general classification,which is based on a comparison of charge transport and mass transport.By combining the Onsager transport formalism with linear response theory,center-of-mass fluctuations and collective translational dipole fluctuations of the ions in equilibrium are related to transport properties in a lithium-ion battery cell,namely mass transport,charge transport and Li+transport under anion-blocking conditions.The relevance of the classification approach is substantiated by showing that i)it is straightforward to classify highly concentrated electrolytes and that ii)both fast charge transport and fast mass transport are indispensable for achieving fast Li+transport under anion-blocking conditions.
查看更多>>摘要：Scintillation semiconductors play increasingly important medical diagnosis and industrial inspection roles.Recently,two-dimensional(2D)perovskites have been shown to be promising materials for medical X-ray imaging,but they are mostly used in low-energy(≤130 keV)regions.Direct detection of MeV X-rays,which ensure thorough penetration of the thick shell walls of containers,trucks,and aircraft,is also highly desired in practical industrial applications.Unfortunately,scintillation semiconductors for high-energy X-ray detection are currently scarce.Here,This paper reports a 2D(C4H9NH3)2PbBr4 single crystal with outstanding sensitivity and stability toward X-ray radiation that provides an ultra-wide detectable X-ray range of between 8.20 nGyair s-1(50 keV)and 15.24 mGyair s-1(9 MeV).The(C4H9NH3)2PbBr4 single-crystal detector with a vertical structure is used for high-performance X-ray imaging,delivering a good spatial resolution of 4.3 Ip mm-1 in a plane-scan imaging system.Low ionic migration in the 2D perovskite enables the vertical device to be operated with hundreds of keV to MeV X-ray radiation at high bias voltages,leading to a sensitivity of 46.90 μC Gyair-1 cm-2(-1.16 V μm-1)with 9 MeV X-ray radiation,demonstrating that 2D perovskites have enormous potential for high-energy industrial applications.
Sun Kyung HwangIk Jae ParkSe Won SeoJae Hyun Park...
147-152页
查看更多>>摘要：In spite of the high potential economic feasibility of the tandem solar cells consisting of the halide perovskite and the kesterite Cu2ZnSn(S,Se)4(CZTSSe),they have rarely been demonstrated due to the difficulty in implementing solution-processed perovskite top cell on the rough surface of the bottom cells.Here,we firstly demonstrate an efficient monolithic two-terminal perovskite/CZTSSe tandem solar cell by significantly reducing the surface roughness of the electrochemically deposited CZTSSe bottom cell.The surface roughness(Rrms)of the CZTSSe thin film could be reduced from 424 to 86 nm by using the potentiostatic mode rather than using the conventional galvanostatic mode,which can be further reduced to 22 nm after the subsequent ion-milling process.The perovskite top cell with a bandgap of 1.65 eV could be prepared using a solution process on the flattened CZTSSe bottom cell,resulting in the efficient perovskite/CZTSSe tandem solar cells.After the current matching between two subcells involving the thickness control of the perovskite layer,the best performing tandem device exhibited a high conversion efficiency of 17.5％without the hysteresis effect.
查看更多>>摘要：The improvement in the efficiency of inverted perovskite solar cells(PSCs)is significantly limited by undesirable contact at the NiOx/perovskite interface.In this study,a novel microstructure-control technology is proposed for fabrication of porous NiOx films using Pluronic P123 as the structure-directing agent and acetylacetone(AcAc)as the coordination agent.The synthesized porous NiOx films enhanced the hole extraction efficiency and reduced recombination defects at the NiOx/perovskite interface.Consequently,without any modification,the power conversion efficiency(PCE)of the PSC with MAPbl3 as the absorber layer improved from 16.50％to 19.08％.Moreover,the PCE of the device composed of perovskite Cs0.05(MA0.15FA0.85)0.95Pb(I0.85Br0.15)3 improved from 17.49％to 21.42％.Furthermore,the application of the fabricated porous NiOx on fluorine-doped tin oxide(FTO)substrates enabled the fabrication of large-area PSCs(1.2 cm2)with a PCE of 19.63％.This study provides a novel strategy for improving the contact at the NiOx/perovskite interface for the fabrication of high-performance large-area perovskite solar cells.
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