| Recently, with increasing pollution of the fossil fuels, people have a more urgent demand for clean, reusable secondary energy.Lithium-ion batteries has aroused concern for its high energy density, low cost, simple preparation method.However, used, the capacity of the current commercial graphite anode materials is only372mAh·g-1, severely restricted the development of high energy density and high power electronic portable devices and high rate performance electric vehicle power.Metals,like tin, antimony whose capacity is as high as994and660mAh·g-1, are very promising anode materials.However,the embedding and extraction of lithium ions will cause a very large change in volume (approximately300%) in charge/discharge process which make the electrode cracking, peeling and the electrical contact degraded between the particles, or the particles and the current collector, leading to its capacity quickly decay.Now, there are mainly two ways to solve this problem.One is the introduction of other elements to metal or alloy electrode,with the different reaction mechanism between lithium-ion and other various materials to buffer volume expansion during lithium deintercalation.The other is the preparation of the nanostructured or morphology active material to play the advantages of the space configuration, to make the purposes of buffering the volume expansion in charge-discharge and rapidly charge-discharge.This paper combines both of the two ways.Firstly,we prepared Cu(OH)2quasi-one-dimensional needle array by anodic oxidation as a base, then combined with electro-deposition coating SbSn alloys and get CuO O-Sb-Sn nanostructures electrode after heat treatment.Cu-electrode material. Finally, SEM, EDS, XRD and other means are used to characterize the material’s surface morphology, structure, composition, and optimizing the preparation conditions of materials and analysis the impact on the material properties of the structure, morphology and the components. With the use of constant current charge-discharge, cyclic voltammetry, electrochemical impedance and so on to analyze the preparation of material and made the following achievements:(1) In analyzing the behavior of the copper anodizing in KOH solution, Cu (OH)2quasi-one-dimensional needle array electrodes are prepared. By discussing the influence of different anodization time, current density and KOH concentration on the electrode morphology, structure, excellent rate capability of the quasi-one-dimensional CuO needle array electrodes have been prepared combined with the heat treatment in preferable conditions. The optimum reparation conditions:oxidation time is16min, an anode current density of3mA·cm-2,2M KOH, heat treatment temperature is300℃. The electrodes discharge in the range of1.8～0.01v,0.1C conditions, its initial discharge capacity is0.761mAh·cm-2, the first charge capacity is0.176mAh·cm-2, the capacity with few decay after30cycle capacity and the reversible capacity still0.101mAh·cm-2after50cycles; also maintain stable capacity of0.0320mAh·cm-2under5C conditions.(2) In Cu (OH)2quasi-one-dimensional substrate deposition needle array SbSn alloy, by exploring SbSn alloy’s load, peak current pulse electrodeposition, the impact of duty cycle on the electrode structure and morphology, to get the excellent performance of Cu-O-Sb-Sn composite quasi-one-dimensional array of needle electrodes combined with heat treatment. The optimum conditions for the preparation:depositing electricity is4.5C, pulse frequency100Hz, the peak current is25mA·cm-2, the duty cycle is0.2, the heat treatment temperature of400℃. The electrodes in the range of1.8～0.01v discharge,0.1C conditions, initial discharge capacity is3.72mAh·cm-2, the first charge capacity is1.68mA·cm-2, remains as high as1.17mAh·cm-2after50cycles, also can maintain stable capacity of0.46and0.18mAh·cm-2under2C and5C conditions. Besides, we deposited same quality active substance on Cu(OH)2nano-needle array matrix through galvanostatic methods. We found that pulsed electrodeposition particles are smaller, more homogeneous and binding stronger, besides the influence on the overall structure is smaller, the better the electrochemical performance of the electrode at a constant current after deposition.(3) Comparing Cu-O-Sb-Sn composite electrode after heating with before heating, we found out generating a plurality of complex compounds in an air atmosphere after the heat treatment of the electrode. It can cushion volume changes at different stages of extracting lithium-induced, greatly improving its electrochemical properties. We further study the effects of one-dimensional structure of the material properties through using copper base plate, The results show that each nano-needle connected with copper base, it can help to improve the conductivity and the utilization of the active material. The gap between the nano-needle array not only can provide a channel for the rapid migration of lithium ions, but also provide space for volume expansion of the material during charge. So its electrochemical performance is much better than copper base plate electrode. |
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