【摘要】 采用三种不同的化学合成方法制备出形貌不同、结晶水含量不同的氟化铁[Fe F₃·（H₂O）_0.33和β-Fe F₃·3H₂O]材料,并对其结构、形貌进行表征,同时研究了氟化铁作为正极材料的锂电性能。实验结果表明,在三种材料中,介孔球状的Fe F₃·（H₂O）_0.33的电化学性能最为理想,β-Fe F₃·3H₂O方块的电化学性能其次,块状的Fe F₃·（H₂O）_0.33性能最差。其中,球状的Fe F₃·（H₂O）_0.33在142 mA/g电流密度下,循环充放电100圈后放电比容量仍然能够保持在159.1 mAh/g;方块状的β-Fe F₃·3H₂O在474 mA/g的大电流密度下,循环充放电50圈后放电比容量也可以维持在129.2 mAh/g。介孔材料大的比表面积,不仅增加了电解液和电极之间的接触面积,降低了锂离子的扩散路径,而且也能够缓冲循环过程中的体积变化,这些因素共同促进了其优异的电化学性能。更多还原

【Abstract】 Iron trifluoride with different morphologies and contents of crystalline water including FeF₃·（H₂O）0.33 andβ-FeF₃·3H₂O were prepared via different wet-chemistry methods. Their crystal structures and micromorphologies were characterized by XRD and SEM techniques. As cathode materials, mesoporous sphere-like FeF₃·（H₂O）0.33 and cubic-like β-FeF₃·3H₂O structures exhibit better electrochemical performance than bulk-like FeF₃·（H₂O）0.33 particles.The as-prepared mesoporous sphere-like FeF₃·（H₂O）0.33 exhibits a discharge specific capacity of 159.2 mAh/g at 142 mA/g after 100 cycles. Meanwhile, β-FeF₃·3H₂O with cubic structures also delivers excellent cycle stability, even at a high current density of 474 mAh/g, its discharge specific capacity is as high as 129.2 mAh/g after 50 cycles. The remarkable electrochemical performance could be attributed to the large specific surface area of mesoporous materials, which not only effectively increase the contact area between the active materials and the electrolyte and reduce the Li-ion diffusion pathway, but also buffer the volume changes during cycling.更多还原