查看更多>>摘要：Ternary strategy with a suitable third component is a successful strategy to improve the photovoltaic per-formance of organic solar cells(OSCs).Very recently,Y-series based giant molecule acceptors or oligomerized acceptors have emerged as promising materials for achieving highly efficient and stable binary OSCs,while application as third component for ternary OSCs is limited.Here a novel n-extended giant dimeric acceptor,GDF,is developed based on central Y series core fusion and rigid BDT as linker,and then incorporated into the state-of-the-art PM1:PC6 system to construct ternary OSCs.The GDF has a near planar backbone,resulting in increased π-conjugation,excellent crystallinity,and good electron transport capacity.When GDF is introduced into the PM1:PC6 system,it ensues in a cas-cade like the lowest unoccupied molecular orbitals(LUMO)energy level alignment,a complementary absorption band with PM1 and PC6,higher and balanced hole and electron mobility,slightly smaller domain size,and a higher exciton dissociation probability for PM1:PC6:GDF(1:1.1:0.1)blend film.As a consequence,the PM1∶PC6∶GDF(1∶1.1∶0.1)ternary OSC achieves a champion PCE of 19.22％,with a sig-nificantly higher open-circuit voltage and short-circuit current density,compared to 18.45％for the PM1:PC6(1:1.2)binary OSC.Our findings show that employing a π-extended giant dimeric acceptor as a third component significantly improves the photovoltaic performance of ternary OSCs.
查看更多>>摘要：As interest in double perovskites is growing,especially in applications like photovoltaic devices,under-standing their mechanical properties is vital for device durability.Despite extensive exploration of struc-ture and optical properties,research on mechanical aspects is limited.This article builds a vacancy-ordered double perovskite model,employing first-principles calculations to analyze mechanical,bonding,electronic,and optical properties.Results show Cs2HfI6,Cs2SnBr6,Cs2SnI6,and Cs2PtBr6 have Young's moduli below 13 GPa,indicating flexibility.Geometric parameters explain flexibility variations with the changes of B and X site composition.Bonding characteristic exploration reveals the influence of B and X site electronegativity on mechanical strength.Cs2SnBr6 and Cs2PtBr6 are suitable for solar cells,while Cs2HfI6 and Cs2TiCl6 show potential for semi-transparent solar cells.Optical property calculations highlight the high light absorption coefficients of up to 3.5 ×105 cm-1 for Cs2Hfl6 and Cs2TiCl6.Solar cell simulation shows Cs2PtBr6 achieves 22.4％of conversion efficiency.Cs2ZrCl6 holds promise for ionizing radiation detection with its 3.68 eV bandgap and high absorption coefficient.Vacancy-ordered double perovskites offer superior flexibility,providing valuable insights for designing stable and flexible devices.This understanding enhances the development of functional devices based on these perovskites,espe-cially for applications requiring high stability and flexibility.
查看更多>>摘要：The insurmountable charge transfer impedance at the Li metal/solid polymer electrolytes(SPEs)inter-face at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point,dominantly limits their applications in solid-state batteries(SSBs).Although the inorganic filler such as CeO2 nanoparticle content of composite solid polymer electrolytes(CSPEs)can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface,we found that the required content of CeO2 nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs.In this regard,a sandwich-type com-posited solid polymer electrolyte with a 10％CeO2 CSPEs interlayer sandwiched between two 50％CeO2 CSPEs thin layers(sandwiched CSPEs)is constructed to simultaneously achieve low charge transfer impe-dance and superior ionic conductivity at 30 ℃.The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm-2 and 30 ℃.In addition,the LiFePO4/Sandwiched CSPEs/Li cell also exhibits exceptional cycle performance at 30 ℃ and even elevated 120 ℃ without short circuits.Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high perfor-mance at a wide range of temperatures.
查看更多>>摘要：Ultra-high nickel cobalt-free lithium layered oxides are promising cathode material for lithium-ion bat-teries(LIBs)because of their relatively high capacity and low cost.Nevertheless,the high nickel content would induce bulk structure degradation and interfacial environment deterioration,and the absence of Co element reduces the lithium diffusion kinetics,severely limiting the performance liberation of this kind of cathodes.Herein,a multifunctional Ti/Zr dual cation co-doping strategy has been employed to improve the lithium storage performance of LiNi0.9Mn0.1O2(NM91)cathode.On the one hand,the Ti/Zr co-doping weakens the Li+/Ni2+mixing through magnetic interactions due to the inexistence of unpaired electrons for Ti4+and Zr4+,increasing the lithium diffusion rate and suppressing the harmful coexistence of H1 and H2 phases.On the other hand,they enhance the lattice oxygen stability because of the strong Ti-O and Zr-O bonds,inhibiting the undesired H3 phase transition and lattice oxygen loss,improving the bulk structure and cathode-electrolyte interface stability.As a result,the Ti/Zr co-doped NM91(NMTZ)exhibits a 91.2％capacity retention rate after 100 cycles,while that of NM91 is only 82.9％.Also,the NMTZ displays better rate performance than NM91 with output capacities of 115 and 93 mA h g-1 at a high current density of 5 C,respectively.Moreover,the designed NMTZ could enable the full battery to deliver an energy density up to 263 W h kg-1,making the ultra-high nickel cobalt-free lithium layered oxide cathode closer to practical applications.
查看更多>>摘要：Atom-level modulation of the coordination environment for single-atom catalysts(SACs)is considered as an effective strategy for elevating the catalytic performance.For the MNx site,breaking the symmetrical geometry and charge distribution by introducing relatively weak electronegative atoms into the first/sec-ond shell is an efficient way,but it remains challenging for elucidating the underlying mechanism of interaction.Herein,a practical strategy was reported to rationally design single cobalt atoms coordinated with both phosphorus and nitrogen atoms in a hierarchically porous carbon derived from metal-organic frameworks.X-ray absorption spectrum reveals that atomically dispersed Co sites are coordinated with four N atoms in the first shell and varying numbers of P atoms in the second shell(denoted as Co-N/P-C).The prepared catalyst exhibits excellent oxygen reduction reaction(ORR)activity as well as zinc-air bat-tery performance.The introduction of P atoms in the Co-SACs weakens the interaction between Co and N,significantly promoting the adsorption process of*OOH,resulting in the acceleration of reaction kinetics and reduction of thermodynamic barrier,responsible for the increased intrinsic activity.Our discovery provides insights into an ultimate design of single-atom catalysts with adjustable electrocatalytic activ-ities for efficient electrochemical energy conversion.
查看更多>>摘要：Co-free Li-rich layered oxides(LLOs)are emerging as promising cathode materials for Li-ion batteries due to their low cost and high capacity.However,they commonly face severe structural instability and poor electrochemical activity,leading to diminished capacity and voltage performance.Herein,we introduce a Co-free LLO,Li1.167Ni0.222Mn0.611O2(Cf-L1),which features a cooperative structure of Li/Ni mixing and stacking faults.This structure regulates the crystal and electronic structures,resulting in a higher dis-charge capacity of 300.6 mA h g-1 and enhanced rate capability compared to the typical Co-free LLO,Li1.2Ni0.2Mn0.6O2(Cf-Ls).Density functional theory(DFT)indicates that Li/Ni mixing in LLOs leads to increased Li-O-Li configurations and higher anionic redox activities,while stacking faults further opti-mize the electronic interactions of transition metal(TM)3d and non-bonding O 2p orbitals.Moreover,stacking faults accommodate lattice strain,improving electrochemical reversibility during charge/dis-charge cycles,as demonstrated by the in situ XRD of Cf-L1 showing less lattice evolution than Cf-Ls.This study offers a structured approach to developing Co-free LLOs with enhanced capacity,voltage,rate capability,and cyclability,significantly impacting the advancement of the next-generation Li-ion batteries.
查看更多>>摘要：Aqueous zinc-sulfur batteries at room temperature hold great potential for next-generation energy stor-age technology due to their low cost,safety and high energy density.However,slow reaction kinetics and high activation energy at the sulfur cathode pose great challenges for the practical applications.Herein,biomass-derived carbon with single-atomic cobalt sites(MMPC-Co)is synthesized as the cathode in Zn-S batteries.The catalysis of single-atom Co sites greatly promotes the transform of cathode electrolyte interface(CEI)on the cathode surface,while offering accelerated charge transfer rate for high conversion reversibility and large electrochemical surface area(ECSA)for high electrocatalytic current.Furthermore,the rich pore structure not only physically limits sulfur loss,but also accelerates the transport of zinc ions.In addition,the large pore volume of MMPC-Co is able to relieve the stress effect caused by the volume expansion of ZnS during charge/discharge cycles,thereby maintaining the stability of electrode structure.Consequently,the sulfur cathode maintains a high specific capacity of 729.96 mA h g-1 after 500 cycles at 4 A g-1,which is much better than most cathode materials reported in the literature.This work provides new insights into the design and development of room-temperature aqueous Zn-S batteries.
查看更多>>摘要：The large volumetric variations experienced by metal selenides within conversion reaction result in infe-rior rate capability and cycling stability,ultimately hindering the achievement of superior electrochem-ical performance.Herein,metallic Cu2Se encapsulated with N-doped carbon(Cu2Se@NC)was prepared using Cu2O nanocubes as templates through a combination of dopamine polymerization and high-temperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu2Se@NC with excellent electrochemical performance in sodium ion batteries(SIBs)and potassium ion batteries(PIBs).The composite exhibited excellent rate performance(187.7 mA h g-1 at 50 A g-1 in SIBs and 179.4 mA h g-1 at 5 A g-1 in PIBs)and cyclic stability(246.8 mA h g-1 at 10 A g-1 in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction(XRD)and ex situ trans-mission electron microscope(TEM).In particular,the final products in PIBs of K2Se and K2Se3 species were determined after discharging,which is different from that in SIBs with the final species of Na2Se.The density functional theory calculation showed that carbon induces strong coupling and charge inter-actions with Cu2Se,leading to the introduction of built-in electric field on heterojunction to improve elec-tron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.
查看更多>>摘要：Two-dimensional Ruddlesden-Popper(2DRP)perovskite exhibits excellent stability in perovskite solar cells(PSCs)due to introducing hydrophobic long-chain organic spacers.However,the poor charge trans-porting property of bulky organic cation spacers limits the performance of 2DRP PSCs.Inspired by the A-site cation alloying strategy in 3D perovskites,2DRP perovskites with a binary spacer can promote charge transporting compared to the unary spacer counterparts.Herein,the superior MA-based 2DRP perovskite films with a binary spacer,including 3-guanidinopropanoic acid(GPA)and 4-fluorophenethylamine(FPEA)are realized.These films(GPA0.85FPEA0.15)2MA4Pb5I16 show good morphology,large grain size,decreased trap state density,and preferential orientation of the as-prepared film.Accordingly,the pre-sent 2DRP-based PSC with the binary spacer achieves a remarkable efficiency of 18.37％with a Voc of 1.15 V,a Jsc of 20.13 mA cm-2,and an FF of 79.23％.To our knowledge,the PCE value should be the highest for binary spacer MA-based 2DRP(n ≤ 5)PSCs to date.Importantly,owing to the hydrophobic fluorine group of FPEA and the enhanced interlayer interaction by FPEA,the unencapsulated 2DRP PSCs based on binary spacers exhibit much excellent humidity stability and thermal stability than the unary spacer counterparts.
查看更多>>摘要：The low-cost and easy large-scale fabrication advantages of printable mesoscopic perovskite solar cells(p-MPSCs)are overshadowed by their limited photovoltaic conversion efficiency(PCE).Here,we intro-duce the hydrazide derivative of 4-Hydroxybenzoylhydrazine(4-HBH)to improve the PCE of p-MPSCs by inducing enhanced defect passivation.Both carbonyl and hydrazine groups in hydrazide groups pre-sent strong interaction with perovskite.The hydroxyl group,as an electron donor group,increases the electron cloud density of the hydrazide group in 4-HBH under the conjugation of the benzene ring,and thus enhances its interaction with perovskite.Additionally,the hydroxy group itself interacts with perovskite and passivates defects synergistically.The hydrazine agents can also reduce I2 and suppress the loss of iodine in perovskite films,which inhibits the formation of iodine-related defects.Consequently,p-MPSCs with 4-HBH achieve a high PCE of 19.21％,and present well improved stability.
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