| As novel anode materials for rechargeable lithium-ion batteries, copperoxides have been aroused much attention because of their high theoreticalcapacity, safety, environmental benignity and low cost. However, copperoxides suffer from large initial irreversible capacity loss and poor cyclingstability caused by their low electronic conductivity and morphologicalcollapse resulted from large volume expansion during the charge/dischargecycles. To overcome these drawbacks, one feasible approach is fabricatingmaterials directly grown on a conductive substrate. In this work, CuO andCu2O film with various morphologies have been successfully prepared on Cusubstrate using microemulsion methods. Their lithium storage properties havebeen investigated as anode for lithium ion batteries. The prepared copperoxide films overcome the above drawbacks to same extent and enhanced thelithium storage properties. The main points are summarized as follows:1. The precursors of Cu2(OH)2CO3nanospheres film and Cu2(OH)2CO3nanorodsfilm have been firstly prepared directly on Cu substrate, in the system ofCTAB/aqueous solution/isooctane/n-butanol and aqueous solution (containingNaHCO3and (NH4)2S2O8). Through post-heat treatment, porous CuO nanospheresfilm and CuO nanorods film were obtained and used as anode for lithium ion batteries.The lithium storage properties indicate that the porous CuO nanospheres film canrelieve effectively the volume expansion during the charge/discharge cycles andenhance the structure stability. Meanwhile, the large specific surface area can providemore contact area between active material and electrolyte, thus leading to highreversible capacity. At0.1C rate, the first and second discharge capacity of porousCuO nanospheres film can reach1141.9and808.7mAh g-1, which corresponds to theirreversible capacity is333.2mAh g-1with capacity loss of29.2%. After100cycles,its discharge capacity can still reach799.7mAh g-1. At a high rate of3C,120mAhg-1can be obtained.2. The microemulsion system of CTAB/isooctane/n-butanol/aqueoussolution (containing NaOH, NH3·H2O and (NH4)2S2O8) has been employed forone-pot preparation of CuO nanobelts without post-heat treatment on Cusubstrate. They are100nm in width, tens of nanometers in thickness and3μm inlength. The prepared CuO nanobelts film can be directly used as anode for lithium ion batteries. At0.1C rate, the first and second discharge capacity of CuO nanobelts filmcan reach1262.5and782.9mAh g-1, which corresponds to the irreversible capacityis479.6mAh g-1with capacity loss of38%. At a high rate of10C, its dischargecapacity can maintain375.7mAh g-1.3. Cog-like Cu(OH)2film on Cu substrate as precursor are prepared in themicroemulsion system of NaAOT/isooctane/n-butanol/aqueous solution(containing NH3·H2O and H2O2). Hierarchical Cu2O film was obtained throughthe reduction of the precursor using ascorbic acid as the reductant. The effects ofthe concentration of ascorbic acid, reaction time, reaction temperature and differentreductants on the morphology of the Cu2O film have been discussed. Theelectrochemical performance of hierarchical Cu2O film was investigated as the anodefor lithium ion batteries. At0.1C rate, the first and second discharge capacity ofporous Cu2O nanospheres film can reach870and407.5mAh g-1, which correspondsto the irreversible capacity is462.5mAh g-1with capacity loss of53.2%. At a highrate of5C, its discharge capacity can maintain153.3mAh g-1after100cycles. |
