Growth of Ultrafine SnO2 Nanoparticles within Multiwall Carbon Nanotube Networks: Non-Solution Synthesis and Excellent Electrochemical Properties as Anodes for Lithium Ion Batteries

• A novel composite structure with ultrafine SnO2 nanoparticles well-distributed on MWCNT networks was fabricated via a non-solution synthesis through decomposition and oxidation of tin(II) 2-ethylhexanoate (C16H30O4Sn) in air at 350 °C.
• The effect of annealing temperature and atmosphere on product structures was investigated.
• SnO2-MWCNTs as anode materials for LIBs showed excellent cycle and rate performance.
• C16H30O4Sn-MWCNTs can be directly used as paste to fabricate additive-free electrode by simply spreading onto current collector and annealing in air.
• The facile non-solution synthetic strategy is promising for low-cost and large-scale fabrication of high-performance SnO2/CNTs nanocomposite electrodes.

We report a novel non-solution synthesis of ultrafine SnO2 nanoparticles within multiwall carbon nanotube (MWCNT) networks by pre-mixing tin(II) 2-ethylhexanoate (C16H30O4Sn) and MWCNTs and subsequently annealing in air at 350 °C, at which decomposition and oxidation of tin(II) 2-ethylhexanoate readily went on without destroying the MWCNTs. The resultant SnO2 nanoparticles with average size of ∼5 nm were well-distributed either on the surface of MWCNTs or within themselves-constructed networks. When used as anode materials in lithium ion batteries (LIBs), the SnO2-MWCNT nanocomposites showed superior electrochemical properties, delivering discharge capacities of 1144 mAh g−1 at 100 mA g−1 and 1022 mAh g−1 at 200 mA g−1 after 50 cycles, 685 mAh g−1 at 500 mA g−1 and 640 mAh g−1 at 1000 mA g−1 after 100 cycles. Moreover, the mixture of tin(II) 2-ethylhexanoate and MWCNTs can be directly used as paste for fabrication of binder-free SnO2-MWCNT composite electrodes by simply spreading the mixture on current collectors (ex. Ni foam) and annealing in air. The as-prepared SnO2-MWCNT-Ni composite electrode delivered a discharge capacity of 434 mAh g−1 at 500 mA g−1 after 200 cycles. Besides, the present non-solution synthetic strategy is promising for low-cost and large-scale fabrication of SnO2/CNTs nanocomposites as high-performance anodes for electrochemical energy-storage.

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