Vanadium-based cathodes have attracted great interest in aqueous zinc ion batteries(AZIBs)due to their large capacities,good rate performance and facile synthesis in large scale.However,their practical application is ...Vanadium-based cathodes have attracted great interest in aqueous zinc ion batteries(AZIBs)due to their large capacities,good rate performance and facile synthesis in large scale.However,their practical application is greatly hampered by vanadium dissolution issue in conventional dilute electrolytes.Herein,taking a new potassium vanadate K0.486V2O5(KVO)cathode with large interlayer spacing(~0.95 nm)and high capacity as an example,we propose that the cycle life of vanadates can be greatly upgraded in AZIBs by regulating the concentration of ZnCl2 electrolyte,but with no need to approach“water-in-salt”threshold.With the optimized moderate concentration of 15 m ZnCl2 electrolyte,the KVO exhibits the best cycling stability with ~95.02% capacity retention after 1400 cycles.We further design a novel sodium carboxymethyl cellulose(CMC)-moderate concentration ZnCl2 gel electrolyte with high ionic conductivity of 10.08 mS cm^-1 for the first time and assemble a quasi-solid-state AZIB.This device is bendable with remarkable energy density(268.2 Wh kg^−1),excellent stability(97.35% after 2800 cycles),low self-discharge rate,and good environmental(temperature,pressure)suitability,and is capable of powering small electronics.The device also exhibits good electrochemical performance with high KVO mass loading(5 and 10 mg cm^-2).Our work sheds light on the feasibility of using moderately concentrated electrolyte to address the stability issue of aqueous soluble electrode materials.展开更多
Potassium-ion batteries(PIBs)have attracted enormous attention due to the abundance of potassium resources,low cost,fast ionic conductivity of electrolyte and relatively high operating voltage.Despite great effo rts a...Potassium-ion batteries(PIBs)have attracted enormous attention due to the abundance of potassium resources,low cost,fast ionic conductivity of electrolyte and relatively high operating voltage.Despite great effo rts and progress,researches on PIBs are still at the initial stage,especially in the emerging field of flexible and wearable PIBs.The inevitable challenges for PIBs include low reversible capacity,unsatisfactory cycling stability and insufficient energy density,the solution to which mostly relies on designing adva nced electrodes.Binder-free electrodes have emerged as promising electrode architecture for PIBs.Such electrodes avoid the use of insulating binders,which can be designed with various synergistic functional materials to address the aforementioned PIB issues and be endowed with flexibility/wearability.In this review,we mainly summarize the recent progress on binde r-free electrodes for PIBs,with the focus on the methodologies,detailed strategies and functional materials for electrode construction.One strategy for binder-free electrodes is to assemble free-standing architecture with the help of carbon nanotubes(CNTs),graphitic fibers,and other carbon or mechanically robust materials,either alone or in combination.The other effective strategy is current collector substrate-assisted direct growth,including the use of carbon cloth,metal.MXenes and other conductive substrates.Additionally,challenges and research opportunities are put forward at the end as the guidance for future development of binder-free PIB devices.展开更多
Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F...Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothe rmal method for the first time.The cathode is able to exhibit superior rate capability and stable cycling performa nce up to 1000 cycles,due to the surface-assembling of crystalline nanocubes on carbon fibers.In addition,it shows good mechanical flexibility,nearly no capacity decay is observed after continuous bending of 500 times.With this novel cathode and a directly-grown Na_(2)Ti_(2)O_(5) anode,a fully binde r-free Na-ion battery is assembled.It can deliver a high wo rking voltage and increased gravimetric energy/power densities(maximum values:220.2 Wh/kg;5674,7 W/kg),and can power a LED indicator at bending angles fro m 0° to 180°.展开更多
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.51872104,51972257 and 51672205)the National Key R&D Program of China(Grant No.2016YFA0202602)the Natural Science Foundation of Hubei Province(2018CFB581).
文摘Vanadium-based cathodes have attracted great interest in aqueous zinc ion batteries(AZIBs)due to their large capacities,good rate performance and facile synthesis in large scale.However,their practical application is greatly hampered by vanadium dissolution issue in conventional dilute electrolytes.Herein,taking a new potassium vanadate K0.486V2O5(KVO)cathode with large interlayer spacing(~0.95 nm)and high capacity as an example,we propose that the cycle life of vanadates can be greatly upgraded in AZIBs by regulating the concentration of ZnCl2 electrolyte,but with no need to approach“water-in-salt”threshold.With the optimized moderate concentration of 15 m ZnCl2 electrolyte,the KVO exhibits the best cycling stability with ~95.02% capacity retention after 1400 cycles.We further design a novel sodium carboxymethyl cellulose(CMC)-moderate concentration ZnCl2 gel electrolyte with high ionic conductivity of 10.08 mS cm^-1 for the first time and assemble a quasi-solid-state AZIB.This device is bendable with remarkable energy density(268.2 Wh kg^−1),excellent stability(97.35% after 2800 cycles),low self-discharge rate,and good environmental(temperature,pressure)suitability,and is capable of powering small electronics.The device also exhibits good electrochemical performance with high KVO mass loading(5 and 10 mg cm^-2).Our work sheds light on the feasibility of using moderately concentrated electrolyte to address the stability issue of aqueous soluble electrode materials.
基金supported by the National Natural Science Foundation of China(51972257,52072136 and 51872104)the National Key R&D Program of China(2016YFA0202602)the Natural Science Foundation of Hubei Province(2018CFB581).
基金supported by the National Natural Science Foundation of China(Nos.51972257,51672205 and 51872104)the National Key R&D Program of China(No.2016YFA0202602)。
文摘Potassium-ion batteries(PIBs)have attracted enormous attention due to the abundance of potassium resources,low cost,fast ionic conductivity of electrolyte and relatively high operating voltage.Despite great effo rts and progress,researches on PIBs are still at the initial stage,especially in the emerging field of flexible and wearable PIBs.The inevitable challenges for PIBs include low reversible capacity,unsatisfactory cycling stability and insufficient energy density,the solution to which mostly relies on designing adva nced electrodes.Binder-free electrodes have emerged as promising electrode architecture for PIBs.Such electrodes avoid the use of insulating binders,which can be designed with various synergistic functional materials to address the aforementioned PIB issues and be endowed with flexibility/wearability.In this review,we mainly summarize the recent progress on binde r-free electrodes for PIBs,with the focus on the methodologies,detailed strategies and functional materials for electrode construction.One strategy for binder-free electrodes is to assemble free-standing architecture with the help of carbon nanotubes(CNTs),graphitic fibers,and other carbon or mechanically robust materials,either alone or in combination.The other effective strategy is current collector substrate-assisted direct growth,including the use of carbon cloth,metal.MXenes and other conductive substrates.Additionally,challenges and research opportunities are put forward at the end as the guidance for future development of binder-free PIB devices.
基金supported by the National Natural Science Foundation of China (Nos.51972257,51672205 and 21673169)the National Key R&D Program of China (No.2016YFA0202602)。
文摘Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothe rmal method for the first time.The cathode is able to exhibit superior rate capability and stable cycling performa nce up to 1000 cycles,due to the surface-assembling of crystalline nanocubes on carbon fibers.In addition,it shows good mechanical flexibility,nearly no capacity decay is observed after continuous bending of 500 times.With this novel cathode and a directly-grown Na_(2)Ti_(2)O_(5) anode,a fully binde r-free Na-ion battery is assembled.It can deliver a high wo rking voltage and increased gravimetric energy/power densities(maximum values:220.2 Wh/kg;5674,7 W/kg),and can power a LED indicator at bending angles fro m 0° to 180°.
