| In the face of various problems caused by fossil fuels, people begin to look for new energy alternatives which are sustainable. Electrochemical energy storage is an effective form of energy storage and conversion. Because of the characteristics of sustainable and environmentally friendly, more and more researchers pay much attention to it. In this paper, we introduce three kinds of electrode materials of electrochemical energy storage systems and study on the structure, morphology and electrochemical property. The main contents are as follows:(1) Ni-doped SnO2 nanospheres with different molar ratios of Ni have been synthesized via a one-step hydrothermal method using sodium citrate as the chelators and glucose as the soft template. The XRD and Raman patterns indicate that the structure of SnO2 remains unchanged after the doping of the element nickel. The TEM and SEM images reveal that diameter size of the nanospheres was around 100 nm as well as good dispersity. when the content of nickel is 5 mol%, the SnO2 electrodes exhibit the best electrochemical performance. The charge-discharge tests were performed in a voltage window of 0.005-2.0 V and the rate was 0.2 C. For example, the initial reversible capacity is 1267 mAh/g and the capacity retention after 35 cycles is 53.2% for 5 mol% Ni-doped SnO2. It is hypothesized that the nickel doping could decrease the lattice volume expansion effect in the alloying and dealloying process. Thus, the electrochemical performance is significantly improved.(2) We synthesized a new type of multi-walled carbon nanotube (MWCNT) microspheres and applied the carbon framework to the anode of the sodium ion batteries. Commercial aqueous-dispersed MWCNTs of low cost are easily accessible for the large-scale production of the carbon skeleton through a simple spray drying approach. Using zinc powder as the reducing agent, the SnSb alloy is pinned on the surface of carbon nanotubes microspheres through the method of coprecipitation. The particle size of the alloy is about 100 nm and the content is 61.7 wt%. The electrochemical performance tests prove that the alloy material with carbon carrier owns better performance compared with the SnSb alloy without carbon carrier. At the rate of 0.1 C, after 30 cycles, the discharge capacity decaies from 761 mAh/g to 400 mAh/g. When the rate is up to 0.5 C, the electrode still has a discharge capacity of 362 mAh/g.(3) Based on the preparation of multi-walled carbon nanotube microspheres, we used it as a carbon framework for the sulfur cathode of lithium sulfur batteries. The-prepared carbon framework shows a porous microspherical architecture with the particle size of around several micrometers, and the MWCNTs in it are intertwined to construct a three-dimensional (3D) continuous electronic conductive network. For the sulfur cathode, the C/S microspheres (MS-C/S) were facilely prepared by a melt-diffusion method. The obtained MS-C/S electrode displays excellent cycling stability and rate capability. The electrode with a sulfur loading of 2.5 mg/cm2 shows an initial discharge capacity of 983 mAh/g and a stable capacity of 858 mAh/g after 100 cycles at a current rate of 0.2 C. Even when the current rate increases to 0.5 C, a stable capacity of 806 mAh/g is maintained over 100 cycles. |
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