查看更多>>摘要：While transition-metal oxides such as α-MoO3 provide high capacity,their use is limited by modest electronic conductivity and electrochemical instability in aqueous electrolytes.Two-dimensional(2D)MXenes,offer metallic conductivity,but their capacitance is limited in aqueous electrolytes.Insertion of partially solvated cations into Ti3C2 MXene from lithium-based water-in-salt(WIS)electrolytes enables charge storage at positive potentials,allowing a wider potential window and higher capacitance.Herein,we demonstrate that α-MoO3/Ti3C2 hybrids combine the high capacity of α-MoO3 and conductivity of Ti3C2 in WIS(19.8 m LiCI)electrolyte in a wide 1.8 V voltage window.Cyclic voltammograms reveal multiple redox peaks from α-MoO3 in addition to the well-separated peaks of Ti3C2 in the hybrid electrode.This leads to a higher specific charge and a higher rate capability compared to a carbon and binder containing α-MoO3 electrode.These results demonstrate that the addition of MXene to less conductive oxides eliminates the need for conductive carbon additives and binders,leads to a larger amount of charge stored,and increases redox capacity at higher rates.In addition,MXene encapsulated α-MoO3 showed improved electrochemical stability,which was attributed to the suppressed dissolution of α-MoO3.The work suggests that oxide/MXene hybrids are promising for energy storage.
查看更多>>摘要：Conventional lithium-ion batteries(LIBs)with liquid electrolytes are challenged by their big safety concerns,particularly used in electric vehicles.All-solid-state batteries using solid-state electrolytes have been proposed to significantly improve safety yet are impeded by poor interfacial solid-solid contact and fast interface degradation.As a compromising strategy,in situ solidification has been proposed in recent years to fabricate quasi-solid-state batteries,which have great advantages in constructing intimate interfaces and cost-effective mass manufacturing.In this work,quasi-solid-state pouch cells with high loading electrodes(≥3 mAh cm-2)were fabricated via in situ solidification of poly(ethylene glycol)diacrylate-based polymer electrolytes(PEGDA-PEs).Both single-layer and multilayer quasi-solid-state pouch cells(2.0 Ah)have demonstrated stable electrochemical performance over 500 cycles.The superb electrochemical stability is closely related to the formation of robust and compatible interphase,which successfully inhibits interfacial side reactions and prevents interfacial structural degradation.This work demonstrates that in situ solidification is a facile and cost-effective approach to fabricate quasi-solid-state pouch cells with both excellent electrochemical performance and safety.
Jeongyeon LeeYoonbin KimSoyong ParkKang Ho Shin...
17-25页
查看更多>>摘要：Sodium-ion batteries(SIBs)have attracted considerable interest as an alternative to lithium-ion batteries owing to their similar electrochemical performance and superior long-term cycle stability.Organic materials are regarded as promising anode materials for constructing SIBs with high capacity and good retention.However,utilization of organic materials is rather limited by their low energy density and poor stability at high current densities.To overcome these limitations,we utilized a novel polymeric disodium phthalocyanines(pNaPc)as SIB anodes to provide stable coordination sites for Na ions as well as to enhance the stability at high current density.By varying the linker type during a one-pot cyclization and polymerization process,two pNaPc anodes with O-(O-pNaPc)and S-linkers(S-pNaPc)were prepared,and their structural and electrochemical properties were investigated.The O-pNaPc binds Na ions with a lower binding energy compared with S-pNaPc,which leads to more facile Na-ion coordination/dissociation when engaged as SIB anode.The use of O-pNaPc significantly improves the redox kinetics and cycle stability and allows the fabrication of a full cell against Na3V2(PO4)2F3/C cathode,which demonstrates its practical application with high energy density(288 Wh kg-1)and high power density(149 W kg-1).
查看更多>>摘要：As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly important.However,the low-temperature performance of conventional graphite anodes is severely hampered by the poor diffusion kinetics of Li ions(Li+).Here,zinc oxide(ZnO)nanoparticles are incorporated into the expanded graphite to improve Li+diffusion kinetics,resulting in a significant improvement in low-temperature performance.The ZnO-embedded expanded graphite anodes are investigated with different amounts of ZnO to establish the structure-charge storage mechanism-performance relationship with a focus on low-temperature applications.Electrochemical analysis reveals that the ZnO-embedded expanded graphite anode with nano-sized ZnO maintains a large portion of the diffusion-controlled charge storage mechanism at an ultra-low temperature of-50 ℃.Due to this significantly enhanced Li+diffusion rate,a full cell with the ZnO-embedded expanded graphite anode and a LiNi0.88Co0.09Al0.03O2 cathode delivers high capacities of 176 mAh g-1 at 20 ℃ and 86 mAh g-1 at-50 ℃ at a high rate of 1 C.The outstanding low-temperature performance of the composite anode by improving the Li+diffusion kinetics provides important scientific insights into the fundamental design principles of anodes for low-temperature Li-ion battery operation.
查看更多>>摘要：The application of solid polymer electrolytes(SPEs)is severely impeded by the insufficient ionic conductivity and low Li+transference numbers(tLi+).Here,we report an iodine-driven strategy to address both the two long-standing issues of SPEs simultaneously.Electronegative iodine-containing groups introduced on polymer chains effectively attract Li+ions,facilitate Li+transport,and promote the dissociation of Li salts.Meanwhile,iodine is also favorable to alleviate the strong O-Li+coordination through a Lewis acid-base interaction,further improving the ionic conductivity and tLi+.As a proof of concept,an iodinated single-ion conducting polymer electrolyte(IPE)demonstrates a high ionic conductivity of 0.93 mS cm-1 and a high tLi+of 0.86 at 25 ℃,which is among the best results ever reported for SPEs.Moreover,symmetric Li/Li cells with IPE achieve a long-term stability over 2600 h through the in-situ formed LiF-rich interphase.As a result,Li-S battery with IPE maintains a high capacity of 623.7 mAh g-1 over 300 cycles with an average Coulombic efficiency of 99％.When matched with intercalation cathode chemistries,Li/IPE/LiFePO4 and Li/IPE/LiNi0.8Mn0.1Co0.1O2 solid-state batteries also deliver high-capacity retentions of 95％and 97％at 0.2 C after 120 cycles,respectively.
查看更多>>摘要：The enhancement of the fluorination degree of carbon fluorides(CFx)compounds is the most effective method to improve the energy densities of Li/CFx batteries because the specific capacity of CFx is proportional to the molar ratio of F to C atoms(F/C).In this study,B-doped graphene(BG)is prepared by using boric acid as the doping source and then the prepared BG is utilized as the starting material for the preparation of CFx.The B-doping enhances the F/C ratio of CFx without hindering the electrochemical activity of the C-F bond.During the fluorination process,B-containing functional groups are removed from the graphene lattice.This facilitates the formation of a defect-rich graphene matrix,which not only enhances the F/C ratio due to abundant perfluorinated groups at the defective edges but also serves as the active site for extra Li+storage.The prepared CFx exhibits the maximum specific capacity of 1204 mAh g-1,which is 39.2％higher than that of CFx obtained directly from graphene oxide(without B-doping).An unprecedented energy density of 2974 Wh kg-1 is achieved for the as-prepared CFx samples,which is significantly higher than the theoretically calculated energy density of commercially available fluorinated graphite(2180 Wh kg-1).Therefore,this study demonstrates a great potential of B-doping to realize the ultrahigh energy density of CFx cathodes for practical applications.
查看更多>>摘要：Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or both.Due to these combined features,reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials;however,there is a significant variation in reported values,ranging between 25 and 350 F g-1.This undermines the structure(e.g.,oxygen functionality and/or surface area)-performance relationships for optimization of cost and scalable factors.This work demonstrates important structure-controlled charge storage relationships.For this,a series of exfoliated graphene(EG)derivatives are produced via thermal-shock exfoliation of GO precursors and following controlled graphitization of EG(GEG)generates materials with varied amounts of porosity,redox-active oxygen groups and graphitic components.Experimental results show significantly varied capacitance values between 30 and 250 F g-1 at 1.0 A g-1 in GEG structures;this suggests that for a given specific surface area the redox-active and hydrophilic oxygen content can boost the capacitance to 250-300％higher compared to typical mesoporous carbon materials.GEGs with identical oxygen functionality show a surface area governed capacitance.This allows to establish direct structure-performance relationships between 1)redox-active oxygen functional concentration and capacitance and 2)surface area and capacitance.
查看更多>>摘要：Aqueous Mg ion batteries(AMIBs)show great potential in energy storage for their advantages of high capacity,abundant resource,and environmental friendliness.However,the development of AMIBs is limited due to the scarcity of suitable anode materials.In this study,a new polymer anode material(PNTAQ)with flower-like nanosheet structure is synthesized for aqueous Mg-Na hybrid-ion battery(AMNHIB).PNTAQ possess carbonyl functional groups which can be oxidized and reduced reversibly in aqueous solution containing alkaline metal ions.PNTAQ displays a discharge specific capacity of 245 mAh g-1 at 50 mA g-1 in 1 M MgCl2+0.5 M NaCl electrolyte,which is much higher than that in single 1 M MgCl2 or 0.5 M NaCl electrolyte.Even cycling at 1000 mA g-1 for 1000 times,the capacity retention can still maintain at 87.2％.A full Mg-Na hybrid-ion cell is assembled by employing β-MnO2 as cathode and PNTAQ as anode material,it exhibits a specific capacity of 91.6 mAh g-1 at 100 mA g-1.The polymer electrode material well maintains its framework structure during the discharge/charge cycling process of the hybrid-ion battery.
查看更多>>摘要：Aqueous supercapacitors(SCs)have been regarded as a promising candidate for commercial energy storage device due to their superior safety,low cost,and environmental benignity.Unfortunately,an age-old challenge of achieving both long electrode lifespan and qualified energy-storage property blocks their practical application.Herein,we develop an electrode-electrolyte integrated optimization strategy to fulfill the real-life device requirements.Electrode optimization simultaneously regulates the nanomorphology and surface chemistry of the tungsten oxide anode,resulting in superior electrochemical performance given by an ideal"bird-nest"structure with optimal oxygen vacancy status;the anodes interact with and are protected from dissolution and structural collapse by the rationally designed hybrid electrolyte with optimized pH and facilitated cation desorption behavior.Collaboratively,a record-breaking durability of no capacitive decay after 250 000 cycles is achieved.On the basis of this integrated optimization,the first aqueous pouch SCs with real-life practicability were manufactured by a soft-package encapsulation technique,which can steadily power commercial 3 C products such as tablets and smartphones and maintain safely working against extreme conditions.This work demonstrates the possibility of using aqueous energy storage devices with enhanced safety and lower cost to replace the commercial organic counterparts for wide range of daily applications.
查看更多>>摘要：Metal-metal battery bears great potential for next-generation large-scale energy storage system because of its simple manufacture process and low production cost.However,the cross-over of metal cations from the cathode to the anode causes a loss in capacity and influences battery stability.Herein,a coating of poly(ionic liquid)(PIL)with poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide)(PDADMA+TFSI-)on a commercial polypropylene(PP)separator serves as an anion exchange membrane for a 3.3 V copper-lithium battery.The PIL has a positively charged polymer backbone that can block the migration of copper ions,thus improving Coulombic efficiency,long-term cycling stability and inhibiting self-discharge of the battery.It can also facilitate the conduction of anions through the membrane and reduce polarization,especially for fast charging/discharging.Bruce-Vincent method gives the transport number in the electrolyte to be 0.25 and 0.04 for PP separator without and with PIL coating,respectively.This suggests that the PIL layer reduces the contribution of the internal current due to cation transport.The use of PIL as a coating layer for commercial PP separator is a cost-effective way to improve overall electrochemical performance of copper-lithium batteries.Compared to PP and polyacrylic acid(PAA)/PP separators,the PIL/PP membrane raises the Coulombic efficiency to 99％and decreases the average discharge voltage drop to about 0.09 V when the current density is increased from 0.1 to 1 mA cm-2.
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