Abstract
Metal oxides have been attractive as high-capacity anode materials for lithium-ion batteries. However, oxide anodes encounter drastic volumetric changes during lithium ion storage through the conversion reaction and alloying/dealloying processes, leading to rapid capacity decay and poor cycling stability. Here, we report a free-standing SnO2@reduced graphene oxide (SnO2@rGO) composite anode, in which SnO2 nanoparticles are tightly wrapped within wrinkled rGO sheets. The SnO2@rGO sheet is assembled in high porosity via an anti-solvent-assisted precipitation of dispersed SnO2 nanoparticles and graphene oxide sheets in the distilled water, followed by the filtration and post-annealing processes. Significantly enhanced lithium storage performance has been obtained of the SnO2@rGO anode compared with the bare SnO2 anode material. A high charge capacity above 700 mAh g−1 can be achieved with a satisfying 95.6% retention after 50 cycles at a current density of 500 mA g−1, superior to reserved 126 mAh g−1 and a much lower 16.8% retention of the bare SnO2 anode. XRD pattern and HRTEM images of the cycled SnO2@rGO anode material verify the expected oxidation of Sn to SnO2 at the fully-charged state in the 50th cycle. In addition, FESEM and TEM images reveal the well-preserved free-standing structure after cycling, which accounts for high reversible capacity and excellent cycling stability of such a SnO2@rGO anode. This work provides a promising SnO2-based anode for high-capacity lithium-ion batteries, together with an effective fabrication adoptable to prepare different free-standing composite materials for device applications.
Highlights
With the rapid development of portable electronic devices, pure electric vehicles and emerging large-scale energy storage systems, lithium-ion batteries are required to at least have high energy and power densities, in order to meet high-grade demands for various practical applications
We report an effective approach to fabricate a free-standing SnO2@reduced graphene oxide (rGO) composite anode through an antisolvent-assisted precipitation followed by the suction filtration
The SnO2 oxide has been extensively reported as a highcapacity anode material for lithium-ion batteries, but suffers from fast capacity decay during cycling, due to drastic volume changes for the lithium storage on the basis of the reversible initial conversion reaction (Equation 1) and successive alloying/dealloying processes (Equation 2) as follows (Huang et al, 2010; Wang et al, 2011; Zhang et al, 2012; Jiang et al, 2017): 4Li+ + SnO2 + 4e− ↔ 2Li2O + Sn capacity delivered: 711 mAh/g xLi+ + Sn + xe− ↔ LixSn (0 ≤ x ≤ 4.4) capacity delivered: 782 mAh/g
Summary
With the rapid development of portable electronic devices, pure electric vehicles and emerging large-scale energy storage systems, lithium-ion batteries are required to at least have high energy and power densities, in order to meet high-grade demands for various practical applications. It would be very interesting to explore assembly methods for the preparation of free-standing graphene-based anodes full of pores and wrinkles, in which active particles are uniformly distributed free of the conductive carbon and binder components, resulting in the maximum capacity contribution of such the anode (Xia et al, 2019; Xing et al, 2020).
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