Preparprtion And Characterization Of Nanocomposite Anode Materials

The development of high power density and long cycle-life rechargeable lithium-ion batteries (LIBs) is a key for the future electric vehicles and portable electronics. Coating or hybridizing transition metal oxides with advanced carbon nanomaterials provides an advanced avenue for exploring new type of electrode materials, because of their signally higher capacities (3-4 times greater than graphite), the ease of large-scale fabrication and rich in reserves. Herein, we are inspired by the biomass resources with its special features (abundance, biological activity and carbon source) to fabricated transition metal oxides/carbon composite for LIBs anode. The main contents are summarized as follows:1. We report a biotemplating method for the fabrication of Fe3O4/Fe/C composite by controlling the nucleation and growth of Fe3O4 onto the cotton surface and followed by an annealing treatment. The approach is based on the electrostatic interactions and hydrothermal method. The Fe3O4/Fe nanoparticles are uniformly adhered to the surface of matrix with range from 20 to 100 nm. Fe3O4/Fe/C is highly stable anode material for high-rate LIBs with extremely excellent cycling performance at high current (365.5 mAh g-1 at 2 A g-1 after 220 cycles, which can be rapidly charge to 100% in 28.3 min). Even after 160 cycles at varied current densities from 1 A g-1 to 10 A g-1, this anode still maintain a high discharge of 524.6 mAh g-1.2. Mesoporous biosilicon-carbon nanosheets with carbon quantum dots embedded (QDs SiO2-C Nanosheets) were synthesized by using abandoned bamboo leaves (BLs) as starting materials at 700℃. Compared to the commercialized graphite anode and other artificial nanostructured carbon materials, the QDs SiO-C Nanosheets anode shows impressive good cycle stability.The multifunctional BLs can also acts as nucleating agent and structural template to fabricate MnO nanocrystal superlattices, the resulting composite exhibited high reversible specific capacity (450.7 mAh g-1 after 160cycles at 0.2 A g-1 and 535 mAh g-1 after 100cycles at 0.1 A g-1). This method has simple process, low cost, abundant source and easy realization of industrialization.3. Hollow MnO/C composite were prepared by using impregnation method and followed by heat treatment. One dimensional hollow MnO nanotubes are dispersed inside the partially graphited carbon matrix. As an anode for Li-ion batteries, the well-designed hollow MnO/C composite deliver a reversible capacity of 680.7 mAh g-1 at 0.2 A g-1 after 190 cycles. We also have experimentally realized a maximal discharge specific energy of 425 Wh kg-1. The well-designed hollow hybrid structure assists in overcoming the issues associated with using manganese oxide in Li-ion Batteries, such as poor electric conductivity, volumetric expansion and structural instability during the electrochemical process.