The investigation on the cathode material of potassium ion batteries(PIBs),one of the most promising alternatives to lithium ion batteries,is of great significance.Potassium vanadium fluorophosphate(KVPO4F)with a high...The investigation on the cathode material of potassium ion batteries(PIBs),one of the most promising alternatives to lithium ion batteries,is of great significance.Potassium vanadium fluorophosphate(KVPO4F)with a high working voltage is an appealing cathode candidate for PIBs,while the poor cycling performance and low electronic conductivity dramatically hinder the application.Herein,a plum pudding model inspired three-dimensional amorphous carbon network modified KVPO4F composite(KVPO4F@3DC)is successfully designed in this study to tackle these problems.In the composite,KVPO4F particles are homogeneously wrapped by a layer of amorphous carbon and bridged by crosslinked large area carbon sheets.As the cathode for PIBs,the KVPO4F@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g^-1 at 20 mA g^-1.An excellent long cycle stability with a capacity retention of 85.4%over 550 cycles at 500 mA g^-1 is achieved.In addition,it maintains 83.6%of its initial capacity at 50 mA g^-1 after 100 cycles at 55℃.The design of KVPO4F@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode,successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.展开更多
Fe3O4 is a promising high-capacity anode material for lithium ion batteries, but challenges including short cycle life and low rate capability hinder its widespread implementation. In this work, a well-defined tubular...Fe3O4 is a promising high-capacity anode material for lithium ion batteries, but challenges including short cycle life and low rate capability hinder its widespread implementation. In this work, a well-defined tubular structure constructed by carbon-coated Fe3O4 has been successfully fabricated with hierarchically porous structure, high surface area, and suitable thickness of carbon layer. Such purposely designed hybrid nanostructures have an enhanced electronic/ionic conductivity, stable electrode/electrolyte interface, and physical buffering effect arising from the nanoscale combination of carbon with Fe3O4, as well as the hollow, aligned and hierarchically porous architectures. When used as an anode material for a lithium-ion half cell, the carbon-coated hierarchical Fe3O4 nanotubes showed excellent cycling performance with a specific capacity of 1,020 mAh.g^-1 at 200 mA.g^-1 after 150 cycles, a capacity retention of ca. 103%. Even at a higher current density of 1,000 mA·g^-1, a capacity of 840 mAh·g^-1 is retained after 300 cycles with no capacity loss. In particular, a superior rate capability can be obtained with a stable capacity of 355 mAh.g^-1 at 8,000 mA·g^-1. The encouraging results indicate that hierarchically tubular hybrid nanostructures can have important implications for the development of high-rate electrodes for future rechargeable lithium ion batteries （LIBs）.展开更多
Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with...Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with large capacity and stable cyclability via a facile approach is essential, but still remains a great challenge. Herein, we employ a one-pot hydrothermal route to fabricate carbon-coated Bi2S3 nanomeshes （Bi2S3/C） as an efficient Li-storage material. The nanomeshes serve as a highly conducting and porous scaffold facilitating electron and ion transport, while the carbon coating layer provides flexible space for efficient reduction of mechanical strain upon electrochemical cycling. Consequently, the fabricated Bi2S3/C exhibits a high and stable capacity delivery in the 0.01-2.5 V region, notably outperforming previously reported Bi2S3 materials. It is able to discharge 472 mA·h·g^-1 at 120 mA.g^-1 over 50 full cycles, and to retain 301 mA·h·g^-1 in the 40th cycle at 600 mA.g^-l, demonstrating the potential of Bi2S3 as electrode materials for rechargeable batteries.展开更多
基金financially supported by the National Natural Science Foundation of China(51672078 and 21473052)Hunan University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Independent Research Project(71675004)Hunan Youth Talents(2016RS3025)。
文摘The investigation on the cathode material of potassium ion batteries(PIBs),one of the most promising alternatives to lithium ion batteries,is of great significance.Potassium vanadium fluorophosphate(KVPO4F)with a high working voltage is an appealing cathode candidate for PIBs,while the poor cycling performance and low electronic conductivity dramatically hinder the application.Herein,a plum pudding model inspired three-dimensional amorphous carbon network modified KVPO4F composite(KVPO4F@3DC)is successfully designed in this study to tackle these problems.In the composite,KVPO4F particles are homogeneously wrapped by a layer of amorphous carbon and bridged by crosslinked large area carbon sheets.As the cathode for PIBs,the KVPO4F@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g^-1 at 20 mA g^-1.An excellent long cycle stability with a capacity retention of 85.4%over 550 cycles at 500 mA g^-1 is achieved.In addition,it maintains 83.6%of its initial capacity at 50 mA g^-1 after 100 cycles at 55℃.The design of KVPO4F@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode,successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.
文摘Fe3O4 is a promising high-capacity anode material for lithium ion batteries, but challenges including short cycle life and low rate capability hinder its widespread implementation. In this work, a well-defined tubular structure constructed by carbon-coated Fe3O4 has been successfully fabricated with hierarchically porous structure, high surface area, and suitable thickness of carbon layer. Such purposely designed hybrid nanostructures have an enhanced electronic/ionic conductivity, stable electrode/electrolyte interface, and physical buffering effect arising from the nanoscale combination of carbon with Fe3O4, as well as the hollow, aligned and hierarchically porous architectures. When used as an anode material for a lithium-ion half cell, the carbon-coated hierarchical Fe3O4 nanotubes showed excellent cycling performance with a specific capacity of 1,020 mAh.g^-1 at 200 mA.g^-1 after 150 cycles, a capacity retention of ca. 103%. Even at a higher current density of 1,000 mA·g^-1, a capacity of 840 mAh·g^-1 is retained after 300 cycles with no capacity loss. In particular, a superior rate capability can be obtained with a stable capacity of 355 mAh.g^-1 at 8,000 mA·g^-1. The encouraging results indicate that hierarchically tubular hybrid nanostructures can have important implications for the development of high-rate electrodes for future rechargeable lithium ion batteries （LIBs）.
文摘Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with large capacity and stable cyclability via a facile approach is essential, but still remains a great challenge. Herein, we employ a one-pot hydrothermal route to fabricate carbon-coated Bi2S3 nanomeshes （Bi2S3/C） as an efficient Li-storage material. The nanomeshes serve as a highly conducting and porous scaffold facilitating electron and ion transport, while the carbon coating layer provides flexible space for efficient reduction of mechanical strain upon electrochemical cycling. Consequently, the fabricated Bi2S3/C exhibits a high and stable capacity delivery in the 0.01-2.5 V region, notably outperforming previously reported Bi2S3 materials. It is able to discharge 472 mA·h·g^-1 at 120 mA.g^-1 over 50 full cycles, and to retain 301 mA·h·g^-1 in the 40th cycle at 600 mA.g^-l, demonstrating the potential of Bi2S3 as electrode materials for rechargeable batteries.
