Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge volume change durin...Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge volume change during cycling. Although two-dimensional silicon-based materials show significantly improved performance, flexible synthesis of such materials is still a challenge. In this work, silicon-based nanosheets with a multilayer structure are synthesized for the first time by a topochemical reaction. The morphology and oxidation state of these nanosheets can be controlled by appropriate choice of reaction media and oxidants. Benefiting from the hierarchical structure and ultrathin size, when the silicon-based nanosheets are employed as anodes they exhibit a charge （delithiation） capacity of 800 mAh/g after 50 cycles with a maximum coulombic efficiency of 99.4% and good rate performance （647 mAh/g at 1 A/g）. This work demonstrates a novel method for preparing nanosheets not only for lithium ion batteries but also having various potential applications in other fields, such as catalysts, electronics and photonics.展开更多
Topochemical ion-exchange reactions between solid micro- and nanostructured metal chalcogenides and aqueous salt solutions are generally used for formation of composite structures based on initial metal chalcogenides ...Topochemical ion-exchange reactions between solid micro- and nanostructured metal chalcogenides and aqueous salt solutions are generally used for formation of composite structures based on initial metal chalcogenides and products of their ion-exchange transformation. However, ion exchange has promises as a route to obtaining both composites and solid solutions based on the initial and the end chalcogenide phases. With the help of the ion-exchange technique, single-phase films of Phi xSnxSe substitutional solid solutions with a tin content up to -2 at.%, which are promising for mid- and long-wavelength infrared radiation （IR） optoelectronics, have been obtained at the interface between PbSe poly- crystalline thin films and SnCl2 aqueous solutions containing sodium citrate. It has been shown that the pH value and temperature of the reaction system play an important role in the ion-exchange process. Incubation of lead selenide （PbSe） films in a tin（II） salt aqueous solution also leads to their modification with oxygen-containing tin compounds to a depth of-3 nm. Differences in the film structure, such as changes in the coherent scattering region sizes and orientation of crystallites along the [220] direction, which arise during the contact with citrate-containing SnCl2 solutions, have also been revealed. For the first time, an idea of the existence of a relatively wide reaction zone of an intragranular topochemical ion-exchange reaction in an aqueous solution, within which substitutional solid solutions can form in micro- and nanostructured systems, has been set forth.展开更多
文摘Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge volume change during cycling. Although two-dimensional silicon-based materials show significantly improved performance, flexible synthesis of such materials is still a challenge. In this work, silicon-based nanosheets with a multilayer structure are synthesized for the first time by a topochemical reaction. The morphology and oxidation state of these nanosheets can be controlled by appropriate choice of reaction media and oxidants. Benefiting from the hierarchical structure and ultrathin size, when the silicon-based nanosheets are employed as anodes they exhibit a charge （delithiation） capacity of 800 mAh/g after 50 cycles with a maximum coulombic efficiency of 99.4% and good rate performance （647 mAh/g at 1 A/g）. This work demonstrates a novel method for preparing nanosheets not only for lithium ion batteries but also having various potential applications in other fields, such as catalysts, electronics and photonics.
基金supported by Act 211 of the Government of the Russian Federation No.02.A03.21.0006the Ministry of Education and Science of Russia under government task No.4.1270.2014/K
文摘Topochemical ion-exchange reactions between solid micro- and nanostructured metal chalcogenides and aqueous salt solutions are generally used for formation of composite structures based on initial metal chalcogenides and products of their ion-exchange transformation. However, ion exchange has promises as a route to obtaining both composites and solid solutions based on the initial and the end chalcogenide phases. With the help of the ion-exchange technique, single-phase films of Phi xSnxSe substitutional solid solutions with a tin content up to -2 at.%, which are promising for mid- and long-wavelength infrared radiation （IR） optoelectronics, have been obtained at the interface between PbSe poly- crystalline thin films and SnCl2 aqueous solutions containing sodium citrate. It has been shown that the pH value and temperature of the reaction system play an important role in the ion-exchange process. Incubation of lead selenide （PbSe） films in a tin（II） salt aqueous solution also leads to their modification with oxygen-containing tin compounds to a depth of-3 nm. Differences in the film structure, such as changes in the coherent scattering region sizes and orientation of crystallites along the [220] direction, which arise during the contact with citrate-containing SnCl2 solutions, have also been revealed. For the first time, an idea of the existence of a relatively wide reaction zone of an intragranular topochemical ion-exchange reaction in an aqueous solution, within which substitutional solid solutions can form in micro- and nanostructured systems, has been set forth.
