查看更多>>摘要：It is highly desirable for the promising sodium storage possessing high rate and long stable capability,which are mainly hindered by the unstable yet conventional solvent-derived organic-rich solid electrolyte interphases.Herein,an electrolyte solvation chemistry is elaborately manipulated to produce an enhanced anion-derived and inorganic components-dominated solid electrolyte interphases by introducing a low permittivity(4.33)bis(2,2,2-trifluoroethyl)ether diluent into the sodium bis(trifluoromethylsulfonyl)imide-di methoxy ethane-based high concentration electrolyte to obtain a localized high concentration electrolyte.The bis(2,2,2-trifluoroethyl)ether breaks the balance of original cation solvation structure and tends to interact with Na+-coordinated dimethoxyethane solvent rather than Na+in high concentration electrolyte,leaving an enhanced Coulombic interaction between Na+and(FSO2)2N,and more(FSO2)2N-can enter the Na+solvation shell,forming a further increased number of Na+-(FSO2)2N--dimethoxyethane clusters(from 82.0％for high concentration electrolyte to 94.3％for localized high concentration electrolyte)at a low salt dosage.The preferential reduction of this(FSO2)2N--enriched clusters rather than the dimethoxyethane-dominated Na+solvation structure produces an enhanced anion-derived and inorganic components-dominated solid electrolyte interphases.The reversible charge storage process of Na is decoupled by operando Raman along with a shift of D and G peaks.Benefiting from the enhanced anion-derived electrode-electrolyte interface,the commercial hard carbon anode in localized high concentration electrolyte shows a well rate capability(5 A g-1,70 mAh g-1),cycle performance and stability(85％of initial capacity after 700 cycles)in comparison to that of high concentration electrolyte(68％)and low concentration electrolyte(only 5％after 400 cycles),indicative of uniqueness and superiorities towards stable Na storage.
查看更多>>摘要：Transition metal oxides are regarded as promising candidates of anode for next-generation lithium-ion batteries(LIBs)due to their ultrahigh theoretical capacity and low cost,but are restricted by their low conductivity and large volume expansion during Li+intercalation.Herein,we designed and constructed a structurally integrated 3D carbon tube(3D-CT)grid film with Mn3O4 nanoparticles(Mn3O4-NPs)and carbon nanotubes(CNTs)filled in the inner cavity of CTs(denoted as Mn3O4-NPs/CNTs@3D-CT)as high-performance free-standing anode for LIBs.The Mn3O4-NPs/CNTs@3D-CT grid with Mn3O4-NPs filled in the inner cavity of 3D-CT not only afford sufficient space to overcome the damage caused by the volume expansion of Mn3O4-NPs during charge and discharge processes,but also achieves highly efficient channels for the fast transport of both electrons and Li+during cycling,thus offering outstanding electrochemical performance(865 mAh g-1 at 1 A g-1 after 300 cycles)and excellent rate capability(418 mAh g-1 at 4 A g-1)based on the total mass of electrode.The unique 3D-CT framework structure would open up a new route to the highly stable,high-capacity,and excellent cycle and high-rate performance free-standing electrodes for high-performance Li-ion storage.
查看更多>>摘要：The pursuit of high-performance electrode materials is highly desired to meet the demand of batteries with high energy and power density.However,a deep understanding of the charge storage mechanism is always challenging,which limits the development of advanced electrode materials.Herein,high-resolution mass spectroscopy(HR-MS)is employed to detect the evolution of organic electrode materials during the redox process and reveal the charge storage mechanism,by using small molecular oxamides as an example,which have ortho-carbonyls and are therefore potential electrochemical active materials for batteries.The HR-MS results adequately proved that the oxamides could reversibly store lithium ions in the voltage window of 1.5-3.8 V.Upon deeper reduction,the oxamides would decompose due to the cleavage of the C-N bonds in oxamide structures,which could be proved by the fragments detected by HR-MS,1H NMR,and the generation of NH3 after the reduction of oxamide by Li.This work provides a strategy to deeply understand the charge storage mechanism of organic electrode materials and will stimulate the further development of characterization techniques to reveal the charge storage mechanism for developing high-performance electrode materials.
查看更多>>摘要：The ether electrolytes usually outperform ester electrolytes by evaluating sodium-ion batteries(SIBs)rate performance,which is a near-unanimous conclusion of previous studies based on an essential configuration of the half-cell test.However,here we find that contrary to consensus,the ester electrolyte shows better Na storage capability than the ether electrolyte in full cells.An in-depth analysis of three-electrode,symmetric cell,and in situ XRD tests indicates that traditional half-cell test results are unreliable due to interference from Na electrodes.In particular,Na electrodes show a huge stability difference in ester and ether electrolytes,and ester electrolytes suffer more severe interference than ether electrolytes,resulting in the belief that esters are far inferior to ether electrolytes.More seriously,the more accurate three-electrode test would also suffer from Na electrode interference.Thus,a"corrected half-cell test"protocol is developed to shield the Na electrode interference,revealing the very close super rate capability of hard carbon in ester and ether electrolytes.This work breaks the inherent perception that the kinetic properties of ester electrolytes are inferior to ethers in sodium-ion batteries,reveals the pitfalls of half-cell tests,and proposes a new test protocol for reliable results,greatly accelerating the commercialization of sodium-ion batteries.
查看更多>>摘要：Lithium-ion capacitors(LICs)are becoming important electrochemical energy storage systems due to their great potential to bridge the gap between supercapacitors and lithium-ion batteries.However,capacity lopsidedness and low output voltage greatly hinder the realization of high-energy-density LICs.Herein,a strategy of balancing capacity towards fastest dynamics is proposed to enable high-voltage LICs.Through electrochemical prelithiation of Nb2C to be 1.1 V with 165 mAh g-1,Nb2C//LiFePO4 LICs show a broadened potential window from 3.0 to 4.2 V and an according high energy density of 420 Wh kg-1.Moreover,the underlying mechanism between prelithiation and high voltage is disclosed by electrochemical dynamic analysis.Prelithiation declines the Nb2C anode potential that facilitates electron transmission in the interlayer of two-dimensional Nb2C MXene.This effect induces small drive force for Li+ions deposition and hence weakens the repulsive force from adsorbed ions on the electrode surface.Benefiting from even more Li+ions deposition,a higher voltage is eventually delivered.In addition,prelithiation significantly increases Coulomb efficiency of the 1st cycle from 74％to 90％,which is crucial to commercial application of LICs.
查看更多>>摘要：Lithium metal is a promising candidate for the promotion of the next generation high energy density batteries.The employment of ultrathin Li metal anode with controllable thickness could enable a higher efficiency of Li utilization.Herein,a simple method to fabricate free-standing 10 pm ultrathin Li metal anode is developed in this work.A three-dimensional MnOx-coated CNT framework is constructed through a facile hydrothermal process,utilizing as a host for molten Li infusion,which could not only put forward a simple strategy to modulate the thickness of Li metal film but also restricts the volume expansion.The abundant MnOx nanoparticles acting as lithiophilic sites reduce the Li nucleation barrier and optimize the electrochemical kinetics at the anode/electrolyte interface.As a result,the ultrathin Li composite anode exhibits a superior lifespan expanded to 2000 cycles in a symmetric cell,as well as a better capacity and rate capability than that of bare Li anode in full cell,fulfilling the requirements of high energy density and stable cycling life.Furthermore,a wave-shaped Li metal pouch cell based on the ultrathin Li composite anode is assembled that exhibits remarkable mechanical bending toleration and cyclic stability,demonstrating large potential application in the field of flexible wearable devices.
查看更多>>摘要：Aggregation of polyoxometalates(POM)is largely responsible for the reduced performance of POM-based energy-storage systems.To address this challenge,here,the precise confinement of single Keggin-type POM molecule in a porous carbon(PC)of unimodal super-micropore(micro-PC)is realized.Such precise single-molecule confinement enables sufficient activity center exposure and maximum electron-transfer from micro-PC to POM,which well stabilizes the electron-accepting molecules and thoroughly activates its inherent multi-electron redox-activity.In particular,the redox-activities and electron-accepting properties of the confined POM molecule are revealed to be super-micropore pore size-dependent by experiment and spectroscopy as well as theoretical calculation.Meanwhile,the molecularly dispersed POM molecules confined steadily in the"cage"of micro-PC exhibit unprecedented large-negative-potential stability and multiple-peak redox-activity at an ultra-low loading of～11.4 wt％.As a result,the fabricated solid-state supercapacitor achieves a remarkable areal capacitance,ultrahigh energy and power density of 443 mF cm-2,0.12 mWh cm-2 and 21.1 mW cm-2,respectively.This work establishes a novel strategy for the precise confinement of single POM molecule,providing a versatile approach to inducing the intrinsic activity of POMs for advanced energy-storage systems.
查看更多>>摘要：Zinc(Zn)metal anodes have enticed substantial curiosity for large-scale energy storage owing to inherent safety,high specific and volumetric energy capacities of Zn metal anodes.However,the aqueous electrolyte traditionally employed in Zn batteries suffers severe decomposition due to the narrow voltage stability window.Herein,we introduce N-methylformamide(NMF)as an organic solvent and modulate the solvation structure to obtain a stable organic/aqueous hybrid electrolyte for high-voltage Zn batteries.NMF is not only extremely stable against Zn metal anodes but also reduces the free water molecule availability by creating numerous hydrogen bonds,thereby accommodating high-voltage Zn||LiMn2O4 batteries.The introduction of NMF prevented hydrogen evolution reaction and promoted the creation of an F-rich solid electrolyte interphase,which in turn hampered dendrite growth on Zn anodes.The Zn||LiMn2O4 full cells delivered a high average Coulombic efficiency of 99.7％over 400 cycles.
查看更多>>摘要：Carbonaceous material with favorable K+intercalation feature is considered as a compelling anode for potassium-ion batteries(PIBs).However,the inferior rate performance and cycling stability impede their large-scale application.Here,a facile template method is utilized to synthesize boron doping carbon nanobubbles(BCNBs).The incorporation of boron into the carbon structure introduces abundant defective sites and improves conductivity,facilitating both the intercalation-controlled and capacitive-controlled capacities.Moreover,theoretical calculation proves that boron doping can effectively improve the conductivity and facilitate electrochemical reversibility in PIBs.Correspondingly,the designed BCNBs anode delivers a high specific capacity(464 mAh g-1 at 0.05 A g-1)with an extraordinary rate performance(85.7 mAh g-1 at 50 A g-1),and retains a considerable capacity retention(95.2％relative to the 100th charge after 2000 cycles).Besides,the strategy of pre-forming stable artificial inorganic solid electrolyte interface effectively realizes high initial coulombic efficiency of 79.0％for BCNBs.Impressively,a dual-carbon potassium-ion capacitor coupling BCNBs anode displays a high energy density(177.8 Wh kg-1).This work not only shows great potential for utilizing heteroatom-doping strategy to boost the potassium ion storage but also paves the way for designing high-energy/power storage devices.
查看更多>>摘要：Thiol-ene click reaction is an intriguing strategy for preparing polymer electrolytes due to its high activity,atom economy and less side reaction.However,the explosive reaction rate and the use of non-electrolytic amine catalyst hamper its application in in-situ batteries.Herein,a nitrogen-containing eutectic solution is designed as both the catalyst of the thiol-ene reaction and the plasticizer to in-situ synthesize the gel polymer electrolytes,realizing a mild in-situ gelation process and the preparation of high-performance gel electrolytes.The obtained gel polymer electrolytes exhibit a high ionic conductivity of 4 × 10-4 S cm-1 and lithium-ion transference number(tLi+)of 0.51 at 60 ℃.The as-assembled Li/LiFePO4(LFP)cell delivers a high initial discharge capacity of 155.9 mAh g-1,and a favorable cycling stability with the capacity retention of 82％after 800 cycles at 1 C is also obtained.In addition,this eutectic solution significantly improves the rate performance of the LFP cell with high specific capacity of 141.5 and 126.8 mAh g-1 at 5 C and 10 C,respectively,and the cell can steadily work at various charge-discharge rate for 200 cycles.This powerful and efficient strategy may provide a novel way for in-situ preparing gel polymer electrolytes with desirable comprehensive performances.
维普
万方数据