Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life ...Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life Zn2+storage based on a pseudocapacitive storage mechanism.In the RuO2·H2O||Zn zinc-ion hybrid capacitors with Zn(CF3SO3)2 aqueous electrolyte,the RuO2·H2O cathode can reversibly store Zn2+in a voltage window of 0.4-1.6 V(vs.Zn/Zn2+),delivering a high discharge capacity of 122 mAh g?1.In particular,the zinc-ion hybrid capacitors can be rapidly charged/discharged within 36 s with a very high power density of 16.74 kW kg?1 and a high energy density of 82 Wh kg?1.Besides,the zinc-ion hybrid capacitors demonstrate an ultralong cycle life(over 10,000 charge/discharge cycles).The kinetic analysis elucidates that the ultrafast Zn2+storage in the RuO2·H2O cathode originates from redox pseudocapacitive reactions.This work could greatly facilitate the development of high-power and safe electrochemical energy storage.展开更多
Aqueous rechargeable Zn/MnO2 zinc-ion batteries(ZIBs)are reviving recently due to their low cost,non-toxicity,and natural abundance.However,their energy storage mechanism remains controversial due to their complicated...Aqueous rechargeable Zn/MnO2 zinc-ion batteries(ZIBs)are reviving recently due to their low cost,non-toxicity,and natural abundance.However,their energy storage mechanism remains controversial due to their complicated electrochemical reactions.Meanwhile,to achieve satisfactory cyclic stability and rate performance of the Zn/MnO2 ZIBs,Mn2+ is introduced in the electrolyte(e.g.,ZnSO4 solution),which leads to more complicated reactions inside the ZIBs systems.Herein,based on comprehensive analysis methods including electrochemical analysis and Pourbaix diagram,we provide novel insights into the energy storage mechanism of Zn/MnO2 batteries in the presence of Mn2+.A complex series of electrochemical reactions with the coparticipation of Zn2+,H+,Mn2+,SO42-,and OH-were revealed.During the first discharge process,co-insertion of Zn2+ and H+ promotes the transformation of MnO2 into ZnxMnO4,MnOOH,and Mn2O3,accompanying with increased electrolyte pH and the formation of ZnSO4·3 Zn(OH)2-5 H2O.During the subsequent charge process,ZnxMnO4,MnOOH,and Mn2O3 revert to a-MnO2 with the extraction of Zn2+ and H+,while ZnSO4·3Zn(OH)2·5H2O reacts with Mn2+ to form ZnMn3O7·3 H2O.In the following charge/discharge processes,besides aforementioned electrochemical reactions,Zn2+ reversibly insert into/extract from α-MnO2,ZnxMnO4,and ZnMn3O7·3H2O hosts;ZnSO4·3Zn(OH)2·5 H2O,Zn2Mn3O8,and ZnMn2O4 convert mutually with the participation of Mn2+.This work is believed to provide theoretical guidance for further research on high-performance ZIBs.展开更多
Rechargeable aqueous zinc ion battery(RAZIB)is a promising energy storage system due to its high safety,and high capacity.Among them,manganese oxides with low cost and low toxicity have drawn much attention.However,th...Rechargeable aqueous zinc ion battery(RAZIB)is a promising energy storage system due to its high safety,and high capacity.Among them,manganese oxides with low cost and low toxicity have drawn much attention.However,the under-debate proton reaction mechanism and unsatisfactory electrochemical performance limit their applications.Nanorod b-MnO_(2) synthesized by hydrothermal method is used to investigate the reaction mechanism.As cathode materials for RAZIB,the Zn//b-MnO_(2) delivers 355 mA h g^(-1)(based on cathode mass)at0.1 A g^(-1),and retain 110 mA h g^(-1) after 1000 cycles at 0.2 A g^(-1).Different from conventional zinc ion insertion/extraction mechanism,the proton conversion and Mn ion dissolution/deposition mechanism of b-MnO_(2) is proposed by analyzing the evolution of phase,structure,morphology,and element of b-MnO_(2) electrode,the pH change of electrolyte and the determination of intermediate phase MnO OH.Zinc ion,as a kind of Lewis acid,also provides protons through the formation of ZHS in the proton reaction process.This study of reaction mechanism provides a new perspective for the development of Zn//MnO_(2) battery chemistry.展开更多
Aqueous Zn-ion hybrid supercapacitors(ZHSs)are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance,high safety and low cost.Herein,high-energy and ant...Aqueous Zn-ion hybrid supercapacitors(ZHSs)are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance,high safety and low cost.Herein,high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups.Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage,but also optimizes ion transport kinetics.Consequently,the cathodes show a high gravimetric capacity of 156 mAh g^(−1),superior rate capability(79 mAh g^(−1)with a very short charge/discharge time of 14 s)and exceptional cycling stability.Meanwhile,hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127 Wh kg−1,a high power density of 15.3 kW kg^(−1)and good anti-self-discharge performance.Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn_(4)SO_(4)(OH)_(6)·5H_(2)O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes.The roles of these reactions in energy storage of ZHSs are elucidated.This work not only paves a way for high-performance cathode materials of ZHSs,but also provides a deeper understanding of ZHS electrochemistry.展开更多
Rechargeable aqueous zinc-ion batteries(ZIB s) have been gaining increasing interest for large-scale energy storage applications due to their high safety,good rate capability,and low cost.However,the further developme...Rechargeable aqueous zinc-ion batteries(ZIB s) have been gaining increasing interest for large-scale energy storage applications due to their high safety,good rate capability,and low cost.However,the further development of ZIB s is impeded by two main challenges:Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity,and meanwhile,unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs.In this paper,metal-organic framework(MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIB s with Mn(BTC) MOF cathodes and ZIF-8-coated Zn(ZIF-8@Zn) anodes.Various MOF materials were synthesized,and Mn(BTC) MOF was found to exhibit the best Zn^2+-storage ability with a capacity of 112 mAh g^-1.Zn^2+ storage mechanism of the Mn(BTC) was carefully studied.Besides,ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils.Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes.As a result,the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors,with 8 times longer cycle life than bare Zn foils.Based on the above,high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes,which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles.This work provides a new opportunity for high-performance energy storage system.展开更多
Flexible solid-state battery has several unique characteristics including high flexibility,easy portability,and high safety,which may have broad application prospects in new technology products such as rollup displays...Flexible solid-state battery has several unique characteristics including high flexibility,easy portability,and high safety,which may have broad application prospects in new technology products such as rollup displays,power implantable medical devices,and wearable equipments.The interfacial mechanical and electrochemical problems caused by bending deformation,resulting in the battery damage and failure,are particularly interesting.Herein,a fully coupled electro-chemo-mechanical model is developed based on the actual solid-state battery structure.Concentration-dependent material parameters,stress-dependent diffusion,and potential shift are considered.According to four bending forms(k=8/mm,0/mm,-8/mm,and free),the results show that the negative curvature bending is beneficial to reducing the plastic strain during charging/discharging,while the positive curvature is detrimental.However,with respect to the electrochemical performance,the negative curvature bending creates a negative potential shift,which causes the battery to reach the cut-off voltage earlier and results in capacity loss.These results enlighten us that suitable electrode materials and charging strategy can be tailored to reduce plastic deformation and improve battery capacity for different forms of battery bending.展开更多
Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are ...Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are induced to rearrange and produce volume expansion,thus notably expand the MXenes’interlayer distance to form few-layer MXene.The synthesized few-layer Ti3C2Tx MXene nanosheets display a very small thickness(less than 5 Ti3C2 atom-layers)and expanded interlayer spacing.Consequently,the few-layer Ti3C2Tx exhibits enhanced capacitance(255 F g^-1 vs.177 F g^-1 for the multi-layered Ti3C2Tx)and significantly optimized rate capability(150 F g^-1 at 200 mV s^-1 vs.25 F g^-1 for the multi-layered Ti3C2Tx),because redox-active sites in the few-layer MXene are easily accessible to electrolyte ions.Moreover,an asymmetric supercapacitor is constructed using the few-layer Ti3C2Tx negative electrode and an activated carbon fiber positive electrode.The asymmetric supercapacitor presents a high energy density of 17.9 Wh kg^-1 and a high power density of 14 kW kg^-1,which is inseparable from its wide voltage window of 1.4 V and the good rate performance of the few-layer Ti3C2Tx MXene electrode.Overall,the flash freezing-assist delamination provides an effective and environmental-friendly strategy to synthesize few-layer MXene materials for high-rate electrochemical energy storage.展开更多
Rechargeable aqueous zinc-ion batteries(ZIBs) have become a research hotspot in recent years,due to their huge potential for high-energy,fast-rate,safe and low-cost energy storage.To realize good electrochemical prope...Rechargeable aqueous zinc-ion batteries(ZIBs) have become a research hotspot in recent years,due to their huge potential for high-energy,fast-rate,safe and low-cost energy storage.To realize good electrochemical properties of ZIBs,cathode materials with prominent Zn^(2+) storage capability are highly needed.Herein,we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides.Specifically,K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes.The cathode presented superior Zn^(2+) storage capability in Zn(OTf)_(2) aqueous electrolyte,including high capacity of 321 mAh/g,fast charge/discharge ability(96 mAh/g delivered in 35 s), high energy density of 235 Wh/kg and good cycling performance.Mechanism analysis evidenced that in Zn(OTf)_(2) electrolyte,Zn^(2+) intercalation in the first discharge process promoted K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers to transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O nanoflakes,and the latter served as the Zn^(2+)-storage host in subsequent charge/discharge processes.Benefiting from open-framework crystal structure and sufficiently exposed surface,the Zn_(3+x)V_(2) O_7(OH)_(2)·2_H2 O nanoflakes exhibited high Zn^(2+) diffusion coefficient,smaller charge-transfer resistance and good reversibility of Zn^(2+) intercalation/de-intercalation,thus leading to superior electrochemical performance.While in ZnS04 aqueous electrolyte,the cathode material cannot sufficiently transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O thereby corresponding to inferior electrochemical behaviors.Underlying mechanism and influencing factors of such a transformation phenomenon was also explored.This work not only reports a high-performance ZIB cathode material based on electrochemically induced transformation of vanadium oxides,but also provides new insights into Zn^(2+)-storage electrochemistry.展开更多
Developi ng alter native oxyge n reducti on reactio n (ORR) catalysts to replace precious Pt-based metals with abundant materials is the key challe nge of commercial application of fuel cells. Owing to their various c...Developi ng alter native oxyge n reducti on reactio n (ORR) catalysts to replace precious Pt-based metals with abundant materials is the key challe nge of commercial application of fuel cells. Owing to their various compositi ons and tun able electronic properties, transition metal dichalcogenides (TMDs) have the great potential to realize high-efficiency catalysts for ORR. Here, various 3R-phase dichalcogenides of group VB and VIB transition metals (MX2, M = Nb, Ta, Mo, W;X = S, Se, Te) are investigated for ORR catalysts by using density functional theory calculations. The computed over-potentials of group VB TMDs are much less than those of group VIB TMDs. For group VB TMDs, a volcano-type plot of ORR catalytic activity is established on the adsorption energies of *OH, and NbS2 and TaTe2 exhibit best ORR activity with an oveepotential of 0.54 V. To achieve even better activity, strain engineering is performed to tune ORR catalytic activity, and the minimum over-potential of 0.43 V can be realized. We further dem on strate that the shift of p orbital center of surface chalcoge n elements under strain is responsible for tuning the catalytic activity of TMDs.展开更多
Flexible supercapacitors show a great potential for applications in wearable, miniaturized, portable, large- scale transparent and flexible consumer electronics due to their significant, inherent advantages, such as b...Flexible supercapacitors show a great potential for applications in wearable, miniaturized, portable, large- scale transparent and flexible consumer electronics due to their significant, inherent advantages, such as being flexible, lightweight, low cost and environmentally friendly in comparison with the current energy storage devices. In this report, recent progress on flexible supercapacitors, flexible electrodes and electrolytes is reviewed. In addition, the future challenges and opportunities are discussed.展开更多
Rechargeable aqueous zinc-ion batteries have attracted extensive interest because of low cost and high safety.However,the relationship between structure change of cathode and the zinc ion storage mechanism is still co...Rechargeable aqueous zinc-ion batteries have attracted extensive interest because of low cost and high safety.However,the relationship between structure change of cathode and the zinc ion storage mechanism is still complex and challenging.Herein,open-structured ferric vanadate(Fe_(2)V_(4)O_(13))has been developed as cathode material for aqueous zinc-ion batteries.Intriguingly,two zinc ion storage mechanism can be observed simultaneously for the Fe2V4O13 electrode,i.e.,classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe_(2)V_(4)O_(13),and reversible phase transformation from ferric vanadate to zinc vanadate,which is verified by combined studies using various in-situ and ex-situ techniques.As a result,the Fe_(2)V_(4)O_(13) cathode delivers a high discharge capacity of 380 mAh/g at 0.2 A/g,and stable cyclic performance up to 1000 cycles at 10 A/g in the operating window of 0.2-1.6 V with 2 mol/L Zn(CF_(3)SO_(3))_(2) aqueous solution.Moreover,the assembled Fe_(2)V_(4)O_(13)//Zn flexible quasi-solid-state battery also exhibits a relatively high mechanical strength and good cycling stability.The findings reveal a new perspective of zinc ion storage mechanism for Fe_(2)V_(4)O_(13),which may also be applicable to other vanadate cathodes,providing a new direction for the investigation and design of zinc-ion batteries.展开更多
基金the financial support by the Australian Research Council through the ARC Discovery projects(DP160104340 and DP170100436)Rail Manufacturing Cooperative Research Centre(RMCRC 1.1.1 and RMCRC 1.1.2 projects)+1 种基金financially supported by the International Science&Technology Cooperation Program of China(No.2016YFE0102200)Shenzhen Technical Plan Project(No.JCYJ20160301154114273).
文摘Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life Zn2+storage based on a pseudocapacitive storage mechanism.In the RuO2·H2O||Zn zinc-ion hybrid capacitors with Zn(CF3SO3)2 aqueous electrolyte,the RuO2·H2O cathode can reversibly store Zn2+in a voltage window of 0.4-1.6 V(vs.Zn/Zn2+),delivering a high discharge capacity of 122 mAh g?1.In particular,the zinc-ion hybrid capacitors can be rapidly charged/discharged within 36 s with a very high power density of 16.74 kW kg?1 and a high energy density of 82 Wh kg?1.Besides,the zinc-ion hybrid capacitors demonstrate an ultralong cycle life(over 10,000 charge/discharge cycles).The kinetic analysis elucidates that the ultrafast Zn2+storage in the RuO2·H2O cathode originates from redox pseudocapacitive reactions.This work could greatly facilitate the development of high-power and safe electrochemical energy storage.
基金the financial support from the International Science & Technology Cooperation Program of China (No. 2016YFE0102200)Shenzhen Technical Plan Project (No. JCYJ20160301154114273)+1 种基金National Key Basic Research(973) Program of China (No. 2014CB932400)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01N111)
文摘Aqueous rechargeable Zn/MnO2 zinc-ion batteries(ZIBs)are reviving recently due to their low cost,non-toxicity,and natural abundance.However,their energy storage mechanism remains controversial due to their complicated electrochemical reactions.Meanwhile,to achieve satisfactory cyclic stability and rate performance of the Zn/MnO2 ZIBs,Mn2+ is introduced in the electrolyte(e.g.,ZnSO4 solution),which leads to more complicated reactions inside the ZIBs systems.Herein,based on comprehensive analysis methods including electrochemical analysis and Pourbaix diagram,we provide novel insights into the energy storage mechanism of Zn/MnO2 batteries in the presence of Mn2+.A complex series of electrochemical reactions with the coparticipation of Zn2+,H+,Mn2+,SO42-,and OH-were revealed.During the first discharge process,co-insertion of Zn2+ and H+ promotes the transformation of MnO2 into ZnxMnO4,MnOOH,and Mn2O3,accompanying with increased electrolyte pH and the formation of ZnSO4·3 Zn(OH)2-5 H2O.During the subsequent charge process,ZnxMnO4,MnOOH,and Mn2O3 revert to a-MnO2 with the extraction of Zn2+ and H+,while ZnSO4·3Zn(OH)2·5H2O reacts with Mn2+ to form ZnMn3O7·3 H2O.In the following charge/discharge processes,besides aforementioned electrochemical reactions,Zn2+ reversibly insert into/extract from α-MnO2,ZnxMnO4,and ZnMn3O7·3H2O hosts;ZnSO4·3Zn(OH)2·5 H2O,Zn2Mn3O8,and ZnMn2O4 convert mutually with the participation of Mn2+.This work is believed to provide theoretical guidance for further research on high-performance ZIBs.
基金the financial supports from International Science&Technology Cooperation Program of China(No.2016YFE0102200)Shenzhen Technical Plan Project(No.JCYJ20160301154114273)+1 种基金National Key Basic Research(973)Program of China(No.2014CB932400)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N111)。
文摘Rechargeable aqueous zinc ion battery(RAZIB)is a promising energy storage system due to its high safety,and high capacity.Among them,manganese oxides with low cost and low toxicity have drawn much attention.However,the under-debate proton reaction mechanism and unsatisfactory electrochemical performance limit their applications.Nanorod b-MnO_(2) synthesized by hydrothermal method is used to investigate the reaction mechanism.As cathode materials for RAZIB,the Zn//b-MnO_(2) delivers 355 mA h g^(-1)(based on cathode mass)at0.1 A g^(-1),and retain 110 mA h g^(-1) after 1000 cycles at 0.2 A g^(-1).Different from conventional zinc ion insertion/extraction mechanism,the proton conversion and Mn ion dissolution/deposition mechanism of b-MnO_(2) is proposed by analyzing the evolution of phase,structure,morphology,and element of b-MnO_(2) electrode,the pH change of electrolyte and the determination of intermediate phase MnO OH.Zinc ion,as a kind of Lewis acid,also provides protons through the formation of ZHS in the proton reaction process.This study of reaction mechanism provides a new perspective for the development of Zn//MnO_(2) battery chemistry.
基金National Natural Science Foundation of China(No.52002149)Shenzhen Technical Plan Projects(Nos.JC201105201100A and JCYJ20160301154114273)for financial support.
文摘Aqueous Zn-ion hybrid supercapacitors(ZHSs)are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance,high safety and low cost.Herein,high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups.Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage,but also optimizes ion transport kinetics.Consequently,the cathodes show a high gravimetric capacity of 156 mAh g^(−1),superior rate capability(79 mAh g^(−1)with a very short charge/discharge time of 14 s)and exceptional cycling stability.Meanwhile,hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127 Wh kg−1,a high power density of 15.3 kW kg^(−1)and good anti-self-discharge performance.Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn_(4)SO_(4)(OH)_(6)·5H_(2)O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes.The roles of these reactions in energy storage of ZHSs are elucidated.This work not only paves a way for high-performance cathode materials of ZHSs,but also provides a deeper understanding of ZHS electrochemistry.
基金the financial supports from International Science & Technology Cooperation Program of China (No. 2016YFE0102200)Shenzhen Technical Plan Project (No. JCYJ20160301154114273)+1 种基金National Key Basic Research (973) Program of China (No. 2014CB932400)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01N111)。
文摘Rechargeable aqueous zinc-ion batteries(ZIB s) have been gaining increasing interest for large-scale energy storage applications due to their high safety,good rate capability,and low cost.However,the further development of ZIB s is impeded by two main challenges:Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity,and meanwhile,unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs.In this paper,metal-organic framework(MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIB s with Mn(BTC) MOF cathodes and ZIF-8-coated Zn(ZIF-8@Zn) anodes.Various MOF materials were synthesized,and Mn(BTC) MOF was found to exhibit the best Zn^2+-storage ability with a capacity of 112 mAh g^-1.Zn^2+ storage mechanism of the Mn(BTC) was carefully studied.Besides,ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils.Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes.As a result,the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors,with 8 times longer cycle life than bare Zn foils.Based on the above,high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes,which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles.This work provides a new opportunity for high-performance energy storage system.
基金the National Natural Science Foundation of China(No.11902144)the Postgraduate Research&Practice Innovation Program of Jiangsu Province of China(No.KYCX201074)+1 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.19KJB430022)the Guizhou Provincial General Undergraduate Higher Education Technology Supporting Talent Support Program(No.KY(2018)043)。
文摘Flexible solid-state battery has several unique characteristics including high flexibility,easy portability,and high safety,which may have broad application prospects in new technology products such as rollup displays,power implantable medical devices,and wearable equipments.The interfacial mechanical and electrochemical problems caused by bending deformation,resulting in the battery damage and failure,are particularly interesting.Herein,a fully coupled electro-chemo-mechanical model is developed based on the actual solid-state battery structure.Concentration-dependent material parameters,stress-dependent diffusion,and potential shift are considered.According to four bending forms(k=8/mm,0/mm,-8/mm,and free),the results show that the negative curvature bending is beneficial to reducing the plastic strain during charging/discharging,while the positive curvature is detrimental.However,with respect to the electrochemical performance,the negative curvature bending creates a negative potential shift,which causes the battery to reach the cut-off voltage earlier and results in capacity loss.These results enlighten us that suitable electrode materials and charging strategy can be tailored to reduce plastic deformation and improve battery capacity for different forms of battery bending.
基金financial supports from Shenzhen Technical Plan Project(No.JCYJ20160301154114273No.JCYJ20170412171430026)+2 种基金International Science and Technology Cooperation Program of China(No.2016YFE0102200)National Key Basic Research(973)Program of China(No.2014CB932400)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N111)。
文摘Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are induced to rearrange and produce volume expansion,thus notably expand the MXenes’interlayer distance to form few-layer MXene.The synthesized few-layer Ti3C2Tx MXene nanosheets display a very small thickness(less than 5 Ti3C2 atom-layers)and expanded interlayer spacing.Consequently,the few-layer Ti3C2Tx exhibits enhanced capacitance(255 F g^-1 vs.177 F g^-1 for the multi-layered Ti3C2Tx)and significantly optimized rate capability(150 F g^-1 at 200 mV s^-1 vs.25 F g^-1 for the multi-layered Ti3C2Tx),because redox-active sites in the few-layer MXene are easily accessible to electrolyte ions.Moreover,an asymmetric supercapacitor is constructed using the few-layer Ti3C2Tx negative electrode and an activated carbon fiber positive electrode.The asymmetric supercapacitor presents a high energy density of 17.9 Wh kg^-1 and a high power density of 14 kW kg^-1,which is inseparable from its wide voltage window of 1.4 V and the good rate performance of the few-layer Ti3C2Tx MXene electrode.Overall,the flash freezing-assist delamination provides an effective and environmental-friendly strategy to synthesize few-layer MXene materials for high-rate electrochemical energy storage.
基金financial support by the National Natural Science Foundation of China (52002149)the Shenzhen Technical Plan Project (JCYJ20160301154114273)Australian Research Council through the ARC Discovery projects (DP16010^(4)340 and DP170100436)。
文摘Rechargeable aqueous zinc-ion batteries(ZIBs) have become a research hotspot in recent years,due to their huge potential for high-energy,fast-rate,safe and low-cost energy storage.To realize good electrochemical properties of ZIBs,cathode materials with prominent Zn^(2+) storage capability are highly needed.Herein,we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides.Specifically,K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes.The cathode presented superior Zn^(2+) storage capability in Zn(OTf)_(2) aqueous electrolyte,including high capacity of 321 mAh/g,fast charge/discharge ability(96 mAh/g delivered in 35 s), high energy density of 235 Wh/kg and good cycling performance.Mechanism analysis evidenced that in Zn(OTf)_(2) electrolyte,Zn^(2+) intercalation in the first discharge process promoted K_(2) V_6 O_(16)·1.5 H_(2) O nanofibers to transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O nanoflakes,and the latter served as the Zn^(2+)-storage host in subsequent charge/discharge processes.Benefiting from open-framework crystal structure and sufficiently exposed surface,the Zn_(3+x)V_(2) O_7(OH)_(2)·2_H2 O nanoflakes exhibited high Zn^(2+) diffusion coefficient,smaller charge-transfer resistance and good reversibility of Zn^(2+) intercalation/de-intercalation,thus leading to superior electrochemical performance.While in ZnS04 aqueous electrolyte,the cathode material cannot sufficiently transform into Zn_(3+x)V_(2) O_7(OH)_(2)·2 H_(2) O thereby corresponding to inferior electrochemical behaviors.Underlying mechanism and influencing factors of such a transformation phenomenon was also explored.This work not only reports a high-performance ZIB cathode material based on electrochemically induced transformation of vanadium oxides,but also provides new insights into Zn^(2+)-storage electrochemistry.
基金National Key Research and Development Program of China (No. 2017YFB0701600)National Natural Science Foundation of China (Nos. 11874036, 51622103, and 21573123)+2 种基金Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01N111)Shenzhen Projects for Basic Research (No. JCYJ20170412171430026)National Program for Thousand Young Talents of China.
文摘Developi ng alter native oxyge n reducti on reactio n (ORR) catalysts to replace precious Pt-based metals with abundant materials is the key challe nge of commercial application of fuel cells. Owing to their various compositi ons and tun able electronic properties, transition metal dichalcogenides (TMDs) have the great potential to realize high-efficiency catalysts for ORR. Here, various 3R-phase dichalcogenides of group VB and VIB transition metals (MX2, M = Nb, Ta, Mo, W;X = S, Se, Te) are investigated for ORR catalysts by using density functional theory calculations. The computed over-potentials of group VB TMDs are much less than those of group VIB TMDs. For group VB TMDs, a volcano-type plot of ORR catalytic activity is established on the adsorption energies of *OH, and NbS2 and TaTe2 exhibit best ORR activity with an oveepotential of 0.54 V. To achieve even better activity, strain engineering is performed to tune ORR catalytic activity, and the minimum over-potential of 0.43 V can be realized. We further dem on strate that the shift of p orbital center of surface chalcoge n elements under strain is responsible for tuning the catalytic activity of TMDs.
基金financial support from the National Nature Science Foundation of China under Grants(no. 51102139 and no.50972065)the Shenzhen Technical Plan Projects(no.JC201105201100A)+1 种基金support from Guangdong Province Innovation R&D Team Plan(2009010025)the China Postdoctoral Science Foundation (no.2012M510022)
文摘Flexible supercapacitors show a great potential for applications in wearable, miniaturized, portable, large- scale transparent and flexible consumer electronics due to their significant, inherent advantages, such as being flexible, lightweight, low cost and environmentally friendly in comparison with the current energy storage devices. In this report, recent progress on flexible supercapacitors, flexible electrodes and electrolytes is reviewed. In addition, the future challenges and opportunities are discussed.
基金financially supported by the China Post-doctoral Science Foundation(Nos.2020M682710,2020M682711,2019M652882 and 2019T120725)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110705)+2 种基金National Program for Support of Top-notch Young Professionals(No.x2qsA4210090)National Natural Science Foundation of China,(No.31971614)State Key Laboratory of Pulp and Paper Engineering(No.2020C03).
文摘Rechargeable aqueous zinc-ion batteries have attracted extensive interest because of low cost and high safety.However,the relationship between structure change of cathode and the zinc ion storage mechanism is still complex and challenging.Herein,open-structured ferric vanadate(Fe_(2)V_(4)O_(13))has been developed as cathode material for aqueous zinc-ion batteries.Intriguingly,two zinc ion storage mechanism can be observed simultaneously for the Fe2V4O13 electrode,i.e.,classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe_(2)V_(4)O_(13),and reversible phase transformation from ferric vanadate to zinc vanadate,which is verified by combined studies using various in-situ and ex-situ techniques.As a result,the Fe_(2)V_(4)O_(13) cathode delivers a high discharge capacity of 380 mAh/g at 0.2 A/g,and stable cyclic performance up to 1000 cycles at 10 A/g in the operating window of 0.2-1.6 V with 2 mol/L Zn(CF_(3)SO_(3))_(2) aqueous solution.Moreover,the assembled Fe_(2)V_(4)O_(13)//Zn flexible quasi-solid-state battery also exhibits a relatively high mechanical strength and good cycling stability.The findings reveal a new perspective of zinc ion storage mechanism for Fe_(2)V_(4)O_(13),which may also be applicable to other vanadate cathodes,providing a new direction for the investigation and design of zinc-ion batteries.