烧结温度对Fe(OH)3胶体制备Fe2O3材料储锂性能的影响

Effect of calcination temperature on lithium storage performance of

摘要:

以Fe(OH)3胶体为铁源，探索了一步烧结法制备二维片状结构Fe2O3纳米材料，考察了烧结温度（400、500、600和700 ℃）对材料微观结构和储锂性能的影响。结果表明：400 ℃烧结的样品为α-Fe2O3/Fe3O4复合材料，其他温度烧结得到的是纯的α-Fe2O3；随着烧结温度的升高，组成片状结构致密相连的不规则颗粒逐渐分离，二维片状结构接近坍塌。电化学性能研究发现：500 ℃下得到的样品电极具有相对较好的储锂性能，在1 A/g的电流密度下循环450圈后放电比容量仍具有628.6 mA·h/g，在电流密度为4 A/g时，仍有352.3 mA·h/g的放电比容量。动力学及电极稳定性分析发现，500 ℃烧结的样品Li+扩散系数最大（还原峰和氧化峰对应的扩散系数值分别为：1.57×10-13和4.60×10-13 cm2/s），充放电循环过程中结构稳定性最好。

Abstract:

Fe2O3 electrode materials with two-dimensional flake morphology were prepared by a facile su-crose-assisted one-step sintering method from Fe(OH)3 colloid. The effect of sintering temperature on the microstructure and lithium storage performance of Fe2O3 electrodes was investigated systematically. The results demonstrated that the sample sintered at 400 ℃ is the composites of α-Fe2O3/Fe3O4; while the samples sintered at higher temperatures (500 ℃, 600 ℃, and 700 ℃) are single phase α-Fe2O3. With the increase of sintering temperature, the tight connected irregular particles in the flake gradually get separated so that the two-dimensional flake structure tends to collapse. The results of electrochemical performance tests showed that the sample sintered at 500 ℃ has the best lithium storage performance. For example, a high specific discharge capacity of 628.6 mA·h/g can be retained after 450 cycles at a current density of 1 A/g, and a reversible capacity of 352.3 mA·h/g can be maintained even at 4 A/g. Ki-netic and the cycling stability analysis of electrode indicated that the sample sintered at 500 ℃ has the largest Li+ diffusion coefficient (the diffusion coefficient values corresponding to reduction peak and oxidation peak are 1.57×10-13 cm2/s and 4.60×10-13 cm2/s, respectively) and the best structural integrity stability among the studied samples.