A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were pre-heated at...A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were pre-heated at 300 ℃ and reacted at 750 ℃ under an inert atmosphere to yield the trivalent vanadium phosphate VPO4. In the second step, the product LiVPO4F was synthesized by the reaction with VPO4 and LiF. The LiVPO4F was characterized by X-ray diffraction, scanning electron microscopy, cyclic voltammetry and charge/discharge testing measurements. The LiVPO4F is triclinic crystalline system. At 0.1 C rate, the first charge/discharge capacities were 150.1 mAh·g-1 and 132.6 mAh·g-1; At 0.2 C rate, the first charge/discharge capacities were 142.9 mAh·g-1 and 125.2 mAh·g-1. The LiVPO4F from this work has higher charge/discharge voltage 4.3 V and 4.1 V, respectively.展开更多
对比研究了不同制备方法、电解液组成和碳结构对红磷/碳复合材料电化学性能的影响。利用球磨法制备了红磷/活性炭(AC)复合材料,其较差的首次库伦效率和循环容量表明活性物质红磷没有得到有效利用。对多种电解液进行了优选,得到最优电解...对比研究了不同制备方法、电解液组成和碳结构对红磷/碳复合材料电化学性能的影响。利用球磨法制备了红磷/活性炭(AC)复合材料,其较差的首次库伦效率和循环容量表明活性物质红磷没有得到有效利用。对多种电解液进行了优选,得到最优电解液为1 mol/L Li PF6的EC/EMC/DMC(1:1:1 V/V)酯类电解液。通过气相沉积法制备了红磷/导电碳黑(BP2000)和红磷/活性炭两种复合材料。利用热重分析(TGA)、X射线衍射分析(XRD)、扫描电子显微镜(SEM)、BET比表面分析和循环伏安法(CV)对上述复合材料的形貌、结构和电化学性能进行了研究。结果表明:含磷量为45%的红磷/活性炭复合材料充放电平台分别为1.0 V和0.75 V,具有良好的可逆性。首次放电比容量和充电比容量分别为1500和1200 m Ah/g,库伦效率为82.5%。随后循环中库伦效率超过了97.5%。其1200 m Ah/g的循环容量对应于2.8个电子的可逆反应。以第二次的稳定放电容量计算,50次循环后容量保持率为75.0%。该复合材料较高的循环容量和良好的循环稳定性受益于无定形的活性物质红磷在活性炭导电基底孔结构中,特别是微孔中的均匀分布。展开更多
文摘A new cathode material, LiVPO4F, has been synthesized through two steps of solid-state reactions. In the first step, vanadium pentoxide, ammonium dihydrogen phosphate, and a high surface area carbon were pre-heated at 300 ℃ and reacted at 750 ℃ under an inert atmosphere to yield the trivalent vanadium phosphate VPO4. In the second step, the product LiVPO4F was synthesized by the reaction with VPO4 and LiF. The LiVPO4F was characterized by X-ray diffraction, scanning electron microscopy, cyclic voltammetry and charge/discharge testing measurements. The LiVPO4F is triclinic crystalline system. At 0.1 C rate, the first charge/discharge capacities were 150.1 mAh·g-1 and 132.6 mAh·g-1; At 0.2 C rate, the first charge/discharge capacities were 142.9 mAh·g-1 and 125.2 mAh·g-1. The LiVPO4F from this work has higher charge/discharge voltage 4.3 V and 4.1 V, respectively.
文摘对比研究了不同制备方法、电解液组成和碳结构对红磷/碳复合材料电化学性能的影响。利用球磨法制备了红磷/活性炭(AC)复合材料,其较差的首次库伦效率和循环容量表明活性物质红磷没有得到有效利用。对多种电解液进行了优选,得到最优电解液为1 mol/L Li PF6的EC/EMC/DMC(1:1:1 V/V)酯类电解液。通过气相沉积法制备了红磷/导电碳黑(BP2000)和红磷/活性炭两种复合材料。利用热重分析(TGA)、X射线衍射分析(XRD)、扫描电子显微镜(SEM)、BET比表面分析和循环伏安法(CV)对上述复合材料的形貌、结构和电化学性能进行了研究。结果表明:含磷量为45%的红磷/活性炭复合材料充放电平台分别为1.0 V和0.75 V,具有良好的可逆性。首次放电比容量和充电比容量分别为1500和1200 m Ah/g,库伦效率为82.5%。随后循环中库伦效率超过了97.5%。其1200 m Ah/g的循环容量对应于2.8个电子的可逆反应。以第二次的稳定放电容量计算,50次循环后容量保持率为75.0%。该复合材料较高的循环容量和良好的循环稳定性受益于无定形的活性物质红磷在活性炭导电基底孔结构中,特别是微孔中的均匀分布。
