查看更多>>摘要：Bipolar membranes(BPMs)exhibit the unique capability to regulate the operating environment of elec-trochemical system through the water dissociation-combination processes.However,the industrial uti-lization of BPMs is limited by instability and serious energy consumption.The current-induced membrane discharge(CIMD)at high-current conditions has a negative influence on the performance of anion-exchange membranes,but the underlying ion transport mechanisms in the BPMs remain unclear.Here,the CIMD-coupled Poisson-Nernst-Planck(PNP)equations are used to explore the ion transport mechanisms in the BPMs for both reverse bias and forward bias at neutral and acid-base con-ditions.It is demonstrated that the CIMD effect in the reverse-bias mode can be suppressed by enhancing the diffusive transport of salt counter-ions(Na+and Cl-)into the BPMs,and that in the forward-bias mode with acid-base electrolytes can be suppressed by matching the transport rate of water counter-ions(H3O+and OH-).Suppressing the CIMD can promote the water dissociation in the reverse-bias mode,as well as overcome the plateau of limiting current density and reduce the interfacial blockage of salt co-ions(CI-)in the anion-exchange layer in the forward-bias mode with acid-base electrolytes.Our work highlights the importance of regulating ion crossover transport on improving the performance of BPMs.
查看更多>>摘要：Perovskite solar cells(PSCs)emerge as the most promising photovoltaics(PV)for their high performance and potential convenient cost-effective production routes comparing to the sophomore PV technologies.The printed PSCs with simplified device architecture and fabrication procedures could further enhance the competitive strength of PSC technology.In this work,we present an in-situ defect passivation(ISDP)assisted full-printing of high performance formamidine-lead bromide(FAPbBr3)PSCs.Only three rapid printing steps are involved for electron transporting layer(ETL),perovskite and carbon to form a complete solar cell on the low-cost fluorine-doped tin oxide(FTO)substrate.Long-chain polymer mono-methyl ether polyethylene glycol is particularly utilized as the ISDP passivator,leading to conformal coat-ing on the rough FTO and defect passivation for both ETL and perovskite during printing.A high efficiency of 10.85％(certified 10.14％)and a high Voc up to 1.57 V are achieved for the printed device.The unencap-sulated PSCs maintain above 90％of the initial efficiency after continuously heating at 85 ℃ for 1000 h and over 80％of the efficiency after the maximum power point tracking for 3500 h.The fully printed semitransparent PSCs with carbon grids(CGs)show average visible light transmittance over 33％and an efficiency of 8.81％.
查看更多>>摘要：The use of redox-active organic electrode materials in energy storage is restricted due to their inferior solvent resistance,abysmal conductivity,and the resultant low practical capacity.To address these issues,a class of bipolar p-phenylenediimidazole-based small-molecule compounds are designed and fabricated.The π-conjugated backbone of these small molecules allows for electron delocalization on a big conjugation plane,endowing them with good conductivity and reaction reversibility.Furthermore,when the para-positions of phenylene are occupied by hydroxyl groups,as-formed intramolecular hydro-gen bonds(N-H...O)between phenolic hydroxyl groups and the-NH groups of imidazole rings further enhance the structural planarity,resulting in higher π-conjugation degree and better conductivity,and thus higher utilization of active sites and electrode capacity,proved by both experimental results and theoretical calculations.The optimized composite electrode DBNQ@rGO-45 shows a high specific capac-ity(～308 mA h g-1at 100 mA g-1)and a long cycling stability(112.9 mA h g-1 after 6000 cycles at 2000 mA g-1).The significantly better electrochemical properties for hydroxyl group-containing com-pounds than those without hydroxyl groups attributed to intramolecular hydrogen bond-induced conju-gation enhancement will inspire the structure design of organic electrodes for better energy storage.
查看更多>>摘要：Traditional garnet solid electrolyte(Li7La3Zr2O12)suffers from low room temperature ionic conductivity,poor air stability,high sintering temperature and energy consumption.Considering the development pro-spects of high-entropy materials with high structural disorder and strong component controllability in the field of electrochemical energy storage,herein,a novel high-entropy garnet-type oxide solid elec-trolyte,Li5.75Ga0.25La3Zr0.5Ti0.5Sn0.5Nb0.5O12(LGLZTSNO)was constructed by partially replacing the Li and Zr sites in Li7La3Zr2O12 with Ga and Ti/Sn/Nb elements,respectively.The experimental and density functional theory(DFT)calculation results show that the high-entropy LGLZTSNO electrolyte has prefer-able room temperature ion conductivity,air stability,interface contact performance with lithium anode,and the ability to suppress lithium dendrites.Thanks to the improvement of electrolyte performance,the critical current density of Li/Ag@LGLZTSNO/Li symmetric cell was increased from 0.42 to 1.57 mA cm-2,and the interface area specific impedance(IASR)was reduced from 765.2 to 42.3 Ω cm2.Meanwhile,the Li/Ag@LGLZTSNO/LFP full cell also exhibits excellent rate performance and cycling performance(148 mA h g-1 at 0.1 C and 124 mA h g-1 at 0.5 C,capacity retention up to 84.8％after 100 cycles at 0.1 C),showing the application prospects of high-entropy LGLZTSNO solid electrolyte in high-performance all solid state lithium batteries.
查看更多>>摘要：PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and cost-effectiveness.However,the low oxidation potential of PEO makes the interface problem with the high-voltage cathode extremely severe.In this work,the impedance of PEO-based all-solid-state batteries with high-voltage cathode(NCM811)was studied at different potentials.The Nyquist plots displayed a gyrate arc at low-frequencies for NCM811/PEO interface.Based on the kinetic modeling,it was deduced that there is a decomposition reaction of PEO-matrix in addition to de-embedded reaction of NCM811,and the PEO intermediate product(dehydra-PEO)adsorbed on the electrode surface leading to low-frequency inductive arcs.Furthermore,the distribution of relaxation time shows the dehydra-PEO results in the kinetic tardiness of the charge transfer process in the temporal dimension.Hence,an artificial interface layer(CEIx)was modified on the surface of NCM811 to regulate the potential of cathode/electrolyte interface to prevent the high-voltage deterioration of PEO.NCM/CEIx/PEO batteries exhibit capacity retentions of 96.0％,84.6％,and 76.8％after undergoing 100 cycles at cut-off voltages of 4.1,4.2,and 4.3 V,respectively.Therefore,here the failure mechanism of high-voltage PEO electrolyte is investigated by EIS and a proposed solving strategy is presented.
查看更多>>摘要：Compared with the traditional industrial nitrogen fixation,electrocatalytic methods,especially those uti-lizing double-atom catalysts containing nonmetals,can give good consideration to the economy and environmental protection.However,the existing"acceptance-donation"mechanism is only applicable to bimetallic catalysts and nonmetallic double-atom catalysts containing boron atoms.Herein,a novel"capture-activation-recapture"mechanism for metal-nonmetal double-atom catalyst is proposed to solve the problem by adjusting the coordination environments of nonmetallic atoms and utilizing the activation effect of metal atoms on nitrogen.Based on this mechanism,the nitrogen reduction reaction(NRR)activity of 48 structures is calculated by density functional theory calculation,and four candidates are selected as outstanding electrocatalytic nitrogen reduction catalysts:Si-Fe@NG(UL=-0.14 V),Si-Co@NG(UL=-0.15 V),Si-Mo@BP1(UL=0 V),and Si-Re@BP1(UL=-0.02 V).The analyses of electronic properties further confirm"capture-activation-recapture"mechanism and suggest that the difference in valence electron distribution between metal and Si atoms triggers the activation of N≡N bonds.In addition,a machine learning approach is utilized to generate an expression and an intrinsic descriptor that considers the coordination environment to predict the limiting potential.This study offers profound insight into the synergistic mechanism of TM and Si for NRR and guidance in the design of novel double-atom nitrogen fixation catalysts.
查看更多>>摘要：Sodium metal batteries(SMBs)are rising as viable alternatives to lithium-ion systems due to their supe-rior energy density and sodium's relative abundance.However,SMBs face significant impediments,par-ticularly the exceedingly high negative-to-positive capacity ratios(N/P ratios)which severely encumber energy density and hinder their practical application.Herein,a novel nucleophilic Na3P interphase on aluminum foil has been designed to significantly lower the nucleation energy barrier for sodium atom deposition,resulting in a remarkable reduction of nucleation overpotential and efficient mitigation of dendritic growth at high sodium deposition of 5 mA h cm-2.The interphase promotes stable cycling in anode-less SMB configurations with a low N/P ratio of 1.4 and high cathode mass loading of 11.5 mg cm-2,and demonstrates a substantial increase in high capacity retention of 92.4％after 500 cycles even under 1 C rate condition.This innovation signifies a promising leap forward in the development of high-energy-density,anode-less SMBs,offering a potential solution to the longstanding issues of cycle stability and energy efficiency.
查看更多>>摘要：The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li+migration.Herein,we prepare a dual-salt poly(tetrahydrofuran)-based electrolyte consisting of lithium hexafluorophosphate and lithium difluoro(oxalato)borate(LiDFOB).The Li-salt anions(DFOB-)not only accelerate the ring-opening polymerization of tetrahydrofuran,but also promote the formation of highly ion-conductive and sustainable interphases on Li metal anodes without sacrificing the Li+con-ductivity of electrolytes,which is favorable for Li+transport kinetics at low temperatures.Applications of this polymer electrolyte in Li||LiFePO4 cells show 82.3％capacity retention over 1000 cycles at 30 ℃ and endow stable discharge capacity at-30 ℃.Remarkably,the Li||LiFePO4 cells retain 52％of their room-temperature capacity at-20 ℃ and 0.1 C.This rational design of dual-salt polymer-based electrolytes may provide a new perspective for the stable operation of quasi-solid-state batteries at low temperatures.
查看更多>>摘要：Molybdenum carbide(Mo2C)is a promising non-noble metal electrocatalyst with electronic structures similar to Pt for hydrogen evolution reaction(HER).However,strong H* adsorption at the Mo sites hin-ders the improvement of HER performance.Here,we synthesized monodisperse hollow Mo2C nanoreac-tors,in which the carbon dots(CD)were in situ formed onto the surface of Mo2C through carburization reactions.According to finite element simulation and analysis,the CD@Mo2C possesses better mesoscale diffusion properties than Mo2C alone.The optimized CD@Mo2C nanoreactor demonstrates superior HER performance in alkaline electrolyte with a low overpotential of 57 mV at 10 mA cm-2,which is better than most Mo2C-based electrocatalysts.Moreover,CD@Mo2C exhibits excellent electrochemical stability during 240 h,confirmed by operando Raman and X-ray diffraction(XRD).Density functional theory(DFT)calculations show that carbon dots cause the d-band center of CD@Mo2C to shift away from Fermi level,promoting water dissociation and the desorption of H*.This study provides a reasonable strategy towards high-activity Mo-based HER eletrocatalysts by modulating the strength of Mo-H bonds.
查看更多>>摘要：The engineering of plant-based precursor for nitrogen doping has become one of the most promising strategies to enhance rate capability of hard carbon materials for sodium-ion batteries;however,the poor rate performance is mainly caused by lack of pyridine nitrogen,which often tends to escape because of high temperature in preparation process of hard carbon.In this paper,a high-rate kapok fiber-derived hard carbon is fabricated by cross-linking carboxyl group in 2,6-pyridinedicarboxylic acid with the exposed hydroxyl group on alkalized kapok with assistance of zinc chloride.Specially,a high nitrogen doping content of 4.24％is achieved,most of which are pyridine nitrogen;this is crucial for improving the defect sites and electronic conductivity of hard carbon.The optimized carbon with feature of high nitrogen content,abundant functional groups,degree of disorder,and large layer spacing exhibits high capacity of 401.7 mAh g-1 at a current density of 0.05 A g-1,and more importantly,good rate perfor-mance,for example,even at the current density of 2 A g-1,a specific capacity of 159.5 mAh g-1 can be obtained.These findings make plant-based hard carbon a promising candidate for commercial applica-tion of sodium-ion batteries,achieving high-rate performance with the enhanced pre-cross-linking inter-action between plant precursors and dopants to optimize aromatization process by auxiliary pyrolysis.
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