SnO 2 nano-mulberries anchored onto RGO nanosheets for lithium ion batteries
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Key Laboratory of Surface and Interface Science and Technology, Zhengzhou University of Light Industry, Zhengzhou, Henan 450002, People’s Republic of China 2 Key Laboratory of Surface and Interface Science and Technology, Zhengzhou University of Light Industry, Zhengzhou, Henan 450002, People’s Republic of China; and American Advanced Nanotechnology, Missouri City, Texas 77459, USA a) Address all correspondence to this author. e-mail: [email protected], gfl@zzuli.edu.cn Received: 6 June 2019; accepted: 23 July 2019
Three-dimensional nano-mulberries consisting of SnO2 nanoparticles have been successfully anchored onto the surfaces of reduced graphene oxide (RGO) to construct hierarchical hybrids—SnO2@RGO with a one-pot approach. The SnO2 nano-mulberries with different amounts of RGO have been produced for optimizing their composition effect on Li storage performance. Specifically, SnO2@RGO hybrids incorporated with optimized amount of RGO nanosheets (∼20.8%) exhibit highly enhanced capacity of ∼1025 mA h/g at 0.1 A/g and a reversible capacity of 750 mA h/g over 100 cycles at 0.2 A/g. The materials also deliver much better rate performance with average specific capacity of ∼498 mA h/g at 2 A/g in comparison with that of SnO2 nanomulberries. After cycling for 600 times at 1 A/g, the SnO2@RGO electrodes still maintain high reversible capacity of ∼602 mA h/g, corresponding to 35% of the second cycle and 133% of the 70th discharge capacity.
Introduction Lithium-ion batteries (LIBs) have been widely used in advanced devices, such as mobile phones, electric vehicles, and smart grids [1]. While graphite with a theoretical capacity of 372 mA h/g has been readily applied in assembling anodes for commercial LIBs, it can hardly satisfy the urgent requirements for fabricating advanced LIBs with high energy density, rate performance, and cycling stability [2]. Among the alternative high capacity anode materials, such as silicon, metal sulfides, and metal oxides, SnO2 has been investigated extensively due to its moderate lithiation potential (;1.0 V versus Li/Li1) as well as high specific (1494 mA h/g) and volumetric capacity (10,220 mA h/cm3) [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. Besides, the SnO2 stores Li1 ions in two steps: first conversion reaction (SnO2 1 4Li1 ! Sn 1 2Li2O) yields a capacity of 731 mA h/g and second alloying reaction (Sn 1 4.4Li1 ! Li4.4Sn) contributes to a capacity of 763 mA h/g [13, 14]. Diverse SnO2 nanostructures, such as nanoparticles [15, 16], 1D nanotubes/nanowire [17, 18, 19], 2D nanosheets [20, 21, 22], and 3D flower-like/spheres [23, 24], have been therefore fabricated for optimizing their electrochemical functionalities. However, pristine SnO2 anode materials always suffer from low cycling stability and charge–discharge rate for their poor
ª Materials Research Society 2019
electronic conductivity and large volume change during lithium intercalation and deintercalation [14, 25, 26, 27]. It is therefore critical to incorporate conductive carbonaceous materials into anode materials as constructing 3D hie
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