Redox p-type organic compounds are promising cathode materials for dual-ion batteries.However,the triphenylamine-based polymers usually with agglomerate and intertwined molecular chain nature limit the maximum reactio...Redox p-type organic compounds are promising cathode materials for dual-ion batteries.However,the triphenylamine-based polymers usually with agglomerate and intertwined molecular chain nature limit the maximum reaction of their active sites with large-sized anions.Herein,we demonstrate the application of a small molecule with rigid spirofluorene structu re,namely 2,2’,7,7’-tetrakis(diphenylamine)-9,9’-spirobifluorene(Spiro-TAD),as a cathode material for lithium dual-ion batteries.The inherent sterical structure endows the Spiro-TAD with good chemical stability and large internal space for fast diffusion kinetics of anions in the organic electrolyte.As a result,the Spiro-TAD electrode shows significant insolubility and less steric hindrance,and gives a high actual capacity of 109 mA h g^(-1)(active groups utilization ratio approximately 100%) at 50 mA g^(-1)with a high discharge voltage of 3.6 V(vs.Li+/Li),excellent rate capability(60 mA h g^(-1)at 2000 mA g^(-1)) and extremely stable cycling life(98.4% capacity retention after 1400 cycles at 500 mA g^(-1)) in half cells.Such good electrochemical performance is attributed to the robust and rapid adsorption/desorption of ClO4-anions,which can be proved by the in-situ FTIR and XPS.Moreover,an all-organic lithium dual-ion battery(a-OLDIBs) is constructed using the Spiro-TAD as cathode and 3,4,9,10-Perylenetetracarboxylic diimide(PTCDI) as anode and displays long-term cycling performance of 87.5 mA h g^(-1)after 800 cycles.This study will stimulate further developments in designing all organic battery systems.展开更多
The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power...The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this article,we discuss our design and demonstration of a water-management strategy that supports high current and long-cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water-management approach is based on water vapor feeding in the hydrogen electrode and water evaporation in the iron electrode,thus enabling high current density operation of 300 mA cm^(-2).展开更多
基金supported by the National Natural Science Foundation of China (21905205 and 22109037)the Natural Science Foundation of Tianjin City (20JCYBJC00380)+1 种基金the Advanced Talents Incubation Program of Hebei University (521000981408)the Haihe Laboratory of Sustainable Chemical Transformations(YYJC202110)。
文摘Redox p-type organic compounds are promising cathode materials for dual-ion batteries.However,the triphenylamine-based polymers usually with agglomerate and intertwined molecular chain nature limit the maximum reaction of their active sites with large-sized anions.Herein,we demonstrate the application of a small molecule with rigid spirofluorene structu re,namely 2,2’,7,7’-tetrakis(diphenylamine)-9,9’-spirobifluorene(Spiro-TAD),as a cathode material for lithium dual-ion batteries.The inherent sterical structure endows the Spiro-TAD with good chemical stability and large internal space for fast diffusion kinetics of anions in the organic electrolyte.As a result,the Spiro-TAD electrode shows significant insolubility and less steric hindrance,and gives a high actual capacity of 109 mA h g^(-1)(active groups utilization ratio approximately 100%) at 50 mA g^(-1)with a high discharge voltage of 3.6 V(vs.Li+/Li),excellent rate capability(60 mA h g^(-1)at 2000 mA g^(-1)) and extremely stable cycling life(98.4% capacity retention after 1400 cycles at 500 mA g^(-1)) in half cells.Such good electrochemical performance is attributed to the robust and rapid adsorption/desorption of ClO4-anions,which can be proved by the in-situ FTIR and XPS.Moreover,an all-organic lithium dual-ion battery(a-OLDIBs) is constructed using the Spiro-TAD as cathode and 3,4,9,10-Perylenetetracarboxylic diimide(PTCDI) as anode and displays long-term cycling performance of 87.5 mA h g^(-1)after 800 cycles.This study will stimulate further developments in designing all organic battery systems.
基金financial support primarily from the U.S.Department of Energy Advanced Research Projects Agency–Energy 2015 OPEN program under Contract No.67995support by Energy Storage Materials Initiative(ESMI),which is a Laboratory Directed Research and Development Project at Pacific Northwest National Laboratory(PNNL)PNNL is a multiprogram national laboratory operated for the U.S.Department of Energy(DOE)by Battel e Memorial Institute under Contract no.DE-AC0576RL01830
文摘The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this article,we discuss our design and demonstration of a water-management strategy that supports high current and long-cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water-management approach is based on water vapor feeding in the hydrogen electrode and water evaporation in the iron electrode,thus enabling high current density operation of 300 mA cm^(-2).
