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Zusammenfassung:
Sn-based materials have triggered significant research efforts as anodes for lithium-storage because of their high theoretical capacity. However, the practical applications of Sn-based materials are hindered by low capacity release and poor cycle life, which are mainly caused by structural pulverization and large volume changes on cycling. Herein, a surfactant-assisted assembly method is developed to fabricate 3D nanoarchitectures in which Sn-based nanoparticles are encapsulated by a porous graphene network. More precisely, the graphene forms a 3D cellular network, the interstices of which only partially filled by the electroactive masses, thus establishing a high concentration of interconnected nanosized pores. While the graphene-network itself guarantees fast electron transfer, it is the characteristic presence of nanosized pores in our network that leads to the favorable rate capability and cycling stability by i) accommodating the large volume expansion of Sn-based nanoparticles to ensure integrity of the 3D framework upon cycling and ii) enabling rapid access of Li-ions into Sn-based nanoparticles, which are in addition prevented from agglomerating. As a result, the 3D Sn-based nanoarchitectures deliver excellent electrochemical properties including high rate capability and stable cycle performance. Importantly, this strategy provides a new pathway for the rational engineering of anode materials with large volume changes to achieve improved electrochemical performances.
