Combining metal to form metal phosphide is a promising strategy to address the fast capacity decay of P rooted from its low electronic conductivity and large volume changes upon cycling. Cu_(3)P, which possesses a hig...Combining metal to form metal phosphide is a promising strategy to address the fast capacity decay of P rooted from its low electronic conductivity and large volume changes upon cycling. Cu_(3)P, which possesses a high theoretical gravimetric and volumetric capacity of 363 m Ahág^(-1) and 1028 AháL^(-1) and reasonable volume expansion of 156% during sodiation, was investigated as anode material in SIBs. Hollow-structured Cu_(3)P electrode delivers an initial de-sodiation capacity of * 159.0 m Ahág^(-1) with high capacity retention of ~85.1% over 50 cycles at 0.2 C rate and exhibits good rate performance,retaining 70% of the capacity when the current density increases from 0.2 C to 1.6 C. A 3 V-class full cell consisting of P2-Na_(2/3) Ni_(1/3) Mn_(1/2) Ti_(1/6)O_(2) cathode and Cu_(3)P anode was also assembled, which could achieve an energy density of ~189.3 Whákg^(-1)(based on the mass of both electrode materials) and average discharge voltage of~2.91 V when cycled in 1.0-4.3 V at 0.1C.展开更多
Air-stable layered structured cathodes with high voltage and good cycling stability are highly desired for the practical application of Na-ion batteries.Herein,we report a P2-Na_(2/3)Ni_(2/3)Te_(1/3)O_(2) cathode that...Air-stable layered structured cathodes with high voltage and good cycling stability are highly desired for the practical application of Na-ion batteries.Herein,we report a P2-Na_(2/3)Ni_(2/3)Te_(1/3)O_(2) cathode that is stable in ambient air with an average operating voltage of~3.8 V,demonstrating excellent cycling stability with a capacity retention of more than 92.7%after 500 cycles at 20 mA g^(-1) and good rate capability with 91.9%capacity utilization at 500 mA g^(-1) with respect to capacity at 5 mA g^(-1) between 2.0 and 4.0 V.When the upper cutoff voltage is increased to 4.4 V,P2-Na_(2/3)Ni_(2/3)Te_(1/3)O_(2) delivers a reversible capacity of 71.9 mAh g^(-1) and retains 91.8%of the capacity after 100 cycles at 20 mA g^(-1).The charge compensation during charge/discharge is mainly due to the redox couple of Ni^(2+)/Ni^(3+)in the host with a small amount of contribution from oxygen.The stable structure of the material without phase transformation and with small volume change during charge-discharge allows it to give excellent cycle performance especially when the upper cutoff voltage is not higher than 4.2 V.展开更多
Cu-Li battery with Cu metal cathode and Li metal anode is a candidate for next-generation energy storage system.While self-discharge of the battery can be suppressed with an anion exchange membrane,the voltage polariz...Cu-Li battery with Cu metal cathode and Li metal anode is a candidate for next-generation energy storage system.While self-discharge of the battery can be suppressed with an anion exchange membrane,the voltage polarization depends strongly on the electrolyte.Specifically,when an electrolyte with 3 M LiTFSI(lithium bis(trifluoromethanesulfonyl)imide)in dimethyl carbonate(DMC)is used,overpotential increases with cycling.In this work,we reveal why the voltage polarization changes,and reduce and stabilize it by replacing DMC solvent with a mixed solvent composed of dimethoxyethane(DME)and propylene carbonate(PC).The new electrolyte has higher ionic conductivity and stable solvation structure with more free TFSI-anions upon cycling,which also facilitates uniform plating of metal ions on the metal electrodes.These characteristics enable a stable Cu-Li battery with minimal change in overpotential for more than 1500 cycles at a current density of 2 m A cm^(-2).展开更多
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 catho...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).展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51678182)the Start-up Grant for Shenzhen Oversea High-Level Talents。
文摘Combining metal to form metal phosphide is a promising strategy to address the fast capacity decay of P rooted from its low electronic conductivity and large volume changes upon cycling. Cu_(3)P, which possesses a high theoretical gravimetric and volumetric capacity of 363 m Ahág^(-1) and 1028 AháL^(-1) and reasonable volume expansion of 156% during sodiation, was investigated as anode material in SIBs. Hollow-structured Cu_(3)P electrode delivers an initial de-sodiation capacity of * 159.0 m Ahág^(-1) with high capacity retention of ~85.1% over 50 cycles at 0.2 C rate and exhibits good rate performance,retaining 70% of the capacity when the current density increases from 0.2 C to 1.6 C. A 3 V-class full cell consisting of P2-Na_(2/3) Ni_(1/3) Mn_(1/2) Ti_(1/6)O_(2) cathode and Cu_(3)P anode was also assembled, which could achieve an energy density of ~189.3 Whákg^(-1)(based on the mass of both electrode materials) and average discharge voltage of~2.91 V when cycled in 1.0-4.3 V at 0.1C.
基金supported by National Natural Science Foundation of China(Grant No.52100084)Shenzhen Natural Science Fund(the Stable Support Plan Program GXWD20201230155427003-20200824094017001).
文摘Air-stable layered structured cathodes with high voltage and good cycling stability are highly desired for the practical application of Na-ion batteries.Herein,we report a P2-Na_(2/3)Ni_(2/3)Te_(1/3)O_(2) cathode that is stable in ambient air with an average operating voltage of~3.8 V,demonstrating excellent cycling stability with a capacity retention of more than 92.7%after 500 cycles at 20 mA g^(-1) and good rate capability with 91.9%capacity utilization at 500 mA g^(-1) with respect to capacity at 5 mA g^(-1) between 2.0 and 4.0 V.When the upper cutoff voltage is increased to 4.4 V,P2-Na_(2/3)Ni_(2/3)Te_(1/3)O_(2) delivers a reversible capacity of 71.9 mAh g^(-1) and retains 91.8%of the capacity after 100 cycles at 20 mA g^(-1).The charge compensation during charge/discharge is mainly due to the redox couple of Ni^(2+)/Ni^(3+)in the host with a small amount of contribution from oxygen.The stable structure of the material without phase transformation and with small volume change during charge-discharge allows it to give excellent cycle performance especially when the upper cutoff voltage is not higher than 4.2 V.
基金supported by a Research Matching Grant Scheme(PJ9229008)by the government of Hong Kong Special Administrative Region。
文摘Cu-Li battery with Cu metal cathode and Li metal anode is a candidate for next-generation energy storage system.While self-discharge of the battery can be suppressed with an anion exchange membrane,the voltage polarization depends strongly on the electrolyte.Specifically,when an electrolyte with 3 M LiTFSI(lithium bis(trifluoromethanesulfonyl)imide)in dimethyl carbonate(DMC)is used,overpotential increases with cycling.In this work,we reveal why the voltage polarization changes,and reduce and stabilize it by replacing DMC solvent with a mixed solvent composed of dimethoxyethane(DME)and propylene carbonate(PC).The new electrolyte has higher ionic conductivity and stable solvation structure with more free TFSI-anions upon cycling,which also facilitates uniform plating of metal ions on the metal electrodes.These characteristics enable a stable Cu-Li battery with minimal change in overpotential for more than 1500 cycles at a current density of 2 m A cm^(-2).
基金supported by grant from the Research Grants Council(City U 11305220)of the Hong Kong Special Administrative Region,China
文摘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).
